1
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Li B, Yan Z, Song J, Gao Y, Wang L, Yan X, Shen H, Fan F. Origin of the Efficiency Roll-off in Quantum Dot Light-Emitting Diodes: An Electrically Excited Transient Absorption Spectroscopy Study. NANO LETTERS 2024. [PMID: 39158094 DOI: 10.1021/acs.nanolett.4c03024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/20/2024]
Abstract
In situ characterizations of charge injection dynamics, equilibrated concentration, and electric field distributions shed light on the critical mechanisms of quantum dot light-emitting diodes (QD-LEDs). In this work, we developed electrically excited transient absorption spectroscopy, which can provide the above key information, to investigate the efficiency roll-off of QD-LEDs. We found that the average electron populations per QD are low when QD-LEDs exhibit efficiency roll-off, excluding Auger recombination as the main cause. We also revealed that the weak electrical field inside the QD layer under forward biases has a negligible impact on the efficiency. Interestingly, we found that as the voltage increases the electron concentration in the QD layer saturates at very low levels. When combined with the concomitant efficiency roll-off, we propose electron leakage is the main loss at elevated driving voltages. We further demonstrate that increasing the electron confinement potential with the ZnS shell enables us to efficiently mitigate the efficiency roll-off.
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Affiliation(s)
- Bo Li
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
- Anhui Province Key Laboratory of Scientific Instrument Development and Application, University of Science and Technology of China, Hefei 230026, China
| | - Zhijie Yan
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
- Anhui Province Key Laboratory of Scientific Instrument Development and Application, University of Science and Technology of China, Hefei 230026, China
| | - Jiaojiao Song
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, Henan University, Kaifeng 475000, China
| | - Yan Gao
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, Henan University, Kaifeng 475000, China
| | - Lei Wang
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, Henan University, Kaifeng 475000, China
| | - Xiaohan Yan
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
- Anhui Province Key Laboratory of Scientific Instrument Development and Application, University of Science and Technology of China, Hefei 230026, China
| | - Huaibin Shen
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, Henan University, Kaifeng 475000, China
| | - Fengjia Fan
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
- Anhui Province Key Laboratory of Scientific Instrument Development and Application, University of Science and Technology of China, Hefei 230026, China
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2
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Yan X, Chen C, Wu B, Sun F, Bao H, Tian W, Chang S, Zhong H, Jin S. Probing the Operation of Quantum-Dot Light-Emitting Diodes Using Electrically Pumped Transient Absorption Spectroscopy. J Phys Chem Lett 2024:8593-8599. [PMID: 39141893 DOI: 10.1021/acs.jpclett.4c02127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2024]
Abstract
The quantum-dot light-emitting diode (QLED) is a new generation light emission source that holds great promise for display and lighting applications. Understanding the dynamics of electrons and holes in QLEDs during their operation is crucial for future QLED optimization, but a time-resolved technology capable of characterizing electrons is still lacking. To tackle this challenge, we develop a unique electrically pumped transient absorption (E-TA) spectroscopy to probe the density of electrons in the QD layer with a nanosecond time resolution. The E-TA result provides a comprehensive understanding of the electron dynamics in QLEDs by quantifying the electron injection time after external voltage on, electron release time after external voltage off, and equilibrated electron density (Ne) in the QD layer during device operation. By combining E-TA technology with time-resolved electroluminescence and transient current measurements, we present a comprehensive overview of the dynamics of both electrons and holes in a QLED during operation.
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Affiliation(s)
- Xianchang Yan
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Cuili Chen
- School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Boning Wu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Fengke Sun
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Hui Bao
- School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Wenming Tian
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Shuai Chang
- Faculty of Materials Science, Shenzhen MSU-BIT University, Shenzhen 518172, China
| | - Haizheng Zhong
- School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Shengye Jin
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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3
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Lei H, Lv L, Zhou X, Liu S, Zhu M, Wang H, Qin H, Fang Q, Peng X. Weakly Confined Semiconductor Nanocrystals Excel in Photochemical and Optoelectronic Properties: Evidence from Single-Dot Studies. J Am Chem Soc 2024; 146:21948-21959. [PMID: 39075033 DOI: 10.1021/jacs.4c06993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/31/2024]
Abstract
Single-molecule spectroscopy offers state-resolved measurements on charge-transfer reactions of single semiconductor nanocrystals, leading to the discovery of up to six single-charge transfer reactions with seven transient states for single CdSe/CdS core/shell nanocrystals with water (or oxygen) as the hole (or electron) acceptors. Kinetic rates of three photoinduced single-hole transfer reactions decrease significantly upon increasing the number of excess electrons in a nanocrystal, mainly due to efficient Auger nonradiative recombination of the charged single excitons. Conversely, the kinetic rates of three single-electron transfer reactions of an unexcited nanocrystal increase proportionally to the number of excess electrons in it. Results here reveal that charge-transfer reactions of nanocrystals, at the center of nearly all their functions, could only be deciphered at a state-resolved level on a single nanocrystal. Size-dependent studies validate the weakly confined semiconductor nanocrystals, instead of strongly confined ones (quantum dots), as optimal candidates for photochemical and optoelectronic applications.
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Affiliation(s)
- Haixin Lei
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Liulin Lv
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Xionglin Zhou
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Shaojie Liu
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Meiyi Zhu
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Huifeng Wang
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Haiyan Qin
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Qun Fang
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Xiaogang Peng
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
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4
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Sun X, Chen X, Sun X, Xie J, Zhou L, Chen S. Improved Charge Injection Balance in Quantum Dot Light-Emitting Diodes through Interface Texture. J Phys Chem Lett 2024; 15:7199-7205. [PMID: 38968573 DOI: 10.1021/acs.jpclett.4c01486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2024]
Abstract
The existing methods to improve the charge balance of quantum dot light-emitting diodes (QLEDs) rely on energy-level matching, but these approaches have been limited by material availability and Fermi-level pinning. Here, we propose a solution that does not require changes to the materials' electronic properties. By using nanoimprinting technology to texture the interface between the hole-transporting layer (HTL) and colloidal quantum dot (CQD) layer, we can increase the HTL-CQD contact area. This significantly enhances the hole injection rate while keeping the electron injection rate essentially unchanged. Compared with the conventional planar structure, QLEDs with textured HTL exhibit lower luminance threshold voltage, significantly higher external quantum efficiency at low bias voltages, improved operational stability, and a similar Lambertian factor. Comprehensive measurements confirm that the HTL-CQD interface texture allows more efficient hole injection into CQDs to occur under lower bias, resulting in less CQD charging and more efficient exciton recombination.
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Affiliation(s)
- Xuhao Sun
- Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China
| | - Xingtong Chen
- Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China
| | - Xiaojuan Sun
- Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China
| | - Jiachen Xie
- Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China
| | - Luohe Zhou
- Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China
| | - Song Chen
- Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China
- Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou 215123, Jiangsu, China
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5
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Huo X, Xie Y, Wang X, Zhang L, Yang M. Reduction reactions at the interface between CdS quantum dot and Z-type ligands driven by electron injection in the electroluminescent processes. J Chem Phys 2024; 161:024304. [PMID: 38984958 DOI: 10.1063/5.0196243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 06/24/2024] [Indexed: 07/11/2024] Open
Abstract
The efficient and stable electroluminescence of quantum dots (QDs) is of great importance in their applications in new display technologies. The short service life of blue QDs, however, hinders their development and commercialization. Different mechanisms have been proposed for the destabilization of QDs in electroluminescent processes. Based on real-time time-dependent density functional theory studies on the QD models covered by Z-type ligands (XAc2, X = Cd, Zn, Mg), the structural evolution is simulated to reveal the mechanism of the reduction reactions induced by electron injection. Our simulations reproduce the experimental observations that the reduction reactions occur at the QD-ligand interface, and the reduced Cd atom is almost in a zero valence state. However, different sites are predicted for the reactions in which the surface metal atom of the QD instead of the metal atom in the ligands is reduced. As a result, one of the arms of the chelate ligand leaves the QD, which tends to cause damage to its electroluminescent performance. Our findings contribute to a mechanistic understanding of the reduction reactions that occurred at the QD-ligand interface.
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Affiliation(s)
- Xiangyu Huo
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
| | - Yujuan Xie
- School of Science, Westlake University, Hangzhou 310030, China
| | - Xian Wang
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Li Zhang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
| | - Mingli Yang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
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6
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Chen L, Li D, Wang A, Guo W, Su X, Shang J, Du W, Liu S, Ma Z. Negative corona discharge strategy for efficient quantum dot light-emitting diodes. OPTICS LETTERS 2024; 49:3392-3395. [PMID: 38875628 DOI: 10.1364/ol.515282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 05/24/2024] [Indexed: 06/16/2024]
Abstract
In colloid quantum dot light-emitting diodes (QLEDs), the control of interface states between ZnO and quantum dots (QDs) plays a vital role. We present a straightforward and efficient method using a negative corona discharge to modify the QD film, creating a dipole moment at the interface of QDs and magnesium-doped ZnO (ZnMgO) for balanced charge carrier distribution within the QDs. This process boosts external quantum efficiencies in red, green, and blue QLEDs to 17.71%, 14.53%, and 9.04% respectively. Notably, optimized devices exhibit significant enhancements, especially at lower brightness levels (1000 to 10,000 cd·m-2), vital for applications in mobile displays, TV screens, and indoor lighting.
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Ma S, Cao F, Jia G, Wu Q, Wang S, Yang X. Blue ZnSeTe quantum dot light-emitting diodes with low efficiency roll-off enabled by an in situ hybridization of ZnMgO nanoparticles and amino alcohol molecules. NANOSCALE 2024; 16:10441-10447. [PMID: 38742531 DOI: 10.1039/d4nr01515k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
ZnSeTe quantum dots (QDs) have been employed as promising emitters for blue QD-based light-emitting diodes (QLEDs) due to their unique optoelectronic properties and environmental friendliness. However, such QLEDs usually suffer from serious efficiency roll-off primarily stemming from exciton loss at the interface of the QD layer and the ZnMgO (ZMO) electron transport layer (ETL), which remarkably hinders their application in flat-panel displays. Herein, we propose an in situ hybridization strategy that involves the pre-introduction of amino alcohols into the reaction solution. This strategy effectively suppresses the nucleophilic condensation process by facilitating the coordination of ammonium and hydroxyl groups with metal cations (M2+, i.e. Zn2+ and Mg2+). It slows down the growth rate of ZMO nanoparticles (NPs) while simultaneously facilitating M-O coordination, resulting in the synthesis of small-sized and low-defect ZMO NPs. Notably, this in situ hybridization approach not only alleviates emission quenching at the QDs/ETL interface but also elevates the energy level of the ETL for enhancing carrier injection. We further investigated the impact of amino alcohols with varying carbon-chain lengths on the performance of ZMO NPs and the corresponding LED devices. The optimal blue ZnSeTe QLED demonstrates an impressive EQE of 8.6% with only an ∼11% drop when the current density is increased to 200 mA cm-2, and the device operating lifetime extends to over 1300 h. Conversely, the device utilizing traditionally post-treated ZMO NPs as the ETL exhibits 45% efficiency roll-off and device lifetime of merely 190 h.
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Affiliation(s)
- Shaolin Ma
- Shanghai University Microelectronic R&D Center, Shanghai University, Shanghai 201900, P. R. China
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, P. R. China.
| | - Fan Cao
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, P. R. China.
| | - Guohua Jia
- School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Qianqian Wu
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, P. R. China.
| | - Sheng Wang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, P. R. China.
| | - Xuyong Yang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, P. R. China.
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8
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Sun X, Chen X, Li X, Xie J, Lin X, Shen Q, Wu L, Chen S. Hole-Injection-Barrier Effect on the Degradation of Blue Quantum-Dot Light-Emitting Diodes. ACS NANO 2024. [PMID: 38329720 DOI: 10.1021/acsnano.3c12840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Inefficient hole injection presents a major challenge in achieving stable and commercially viable solution-processed blue electroluminescent devices. Here, we conduct an in-depth study on quantum-dot light-emitting diodes (QLEDs) to understand how the energy levels of common electrodes and hole-transporting layers (HTL) affect device degradation. Our experimental findings reveal a design rule that may seem nonintuitive: combining an electrode and HTL with matched energy levels is most effective in preventing voltage rise and irreversible luminance decay, even though it causes a significant energy offset between the HTL and emissive quantum dots. Using an iterative electrostatic model, we discover that the positive outcomes, including a T95 lifetime of 109 h (luminance = 1000 nits, CIE-y = 0.087), are due to the enhanced p-type doping in the HTL rather than the assumed reduction in barrier heights. Furthermore, our modified hole injection dynamics theory, which considers distributed density-of-states, shows that the increased HTL/quantum-dot energy offset is not a primary concern because the effective barrier height is significantly lower than conventionally assumed. Following this design rule, we expect device stability to be enhanced considerably.
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Affiliation(s)
- Xiaojuan Sun
- Suzhou Key Laboratory of Novel Semiconductor-Optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China
| | - Xingtong Chen
- Suzhou Key Laboratory of Novel Semiconductor-Optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China
| | - Xinrui Li
- Suzhou Key Laboratory of Novel Semiconductor-Optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China
| | - Jiachen Xie
- Suzhou Key Laboratory of Novel Semiconductor-Optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China
| | - Xiongfeng Lin
- TCL Corporate Research, 1001 Zhongshan Park Road, Nanshan District, Shenzhen 518067, Guangdong, China
| | - Qi Shen
- Suzhou Key Laboratory of Novel Semiconductor-Optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China
| | - Longjia Wu
- TCL Corporate Research, 1001 Zhongshan Park Road, Nanshan District, Shenzhen 518067, Guangdong, China
| | - Song Chen
- Suzhou Key Laboratory of Novel Semiconductor-Optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China
- Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou 215123, Jiangsu, China
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Chen Z, Li H, Yuan C, Gao P, Su Q, Chen S. Color Revolution: Prospects and Challenges of Quantum-Dot Light-Emitting Diode Display Technologies. SMALL METHODS 2024; 8:e2300359. [PMID: 37357153 DOI: 10.1002/smtd.202300359] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 05/15/2023] [Indexed: 06/27/2023]
Abstract
Light-emitting diodes (LEDs) based on colloidal quantum-dots (QDs) such as CdSe, InP, and ZnSeTe feature a unique advantage of narrow emission linewidth of ≈20 nm, which can produce highly accurate colors, making them a highly promising technology for the realization of displays with Rec. 2020 color gamut. With the rapid development in the past decades, the performances of red and green QLEDs have been remarkably improved, and their efficiency and lifetime can almost meet industrial requirements. However, the industrialization of QLED displays still faces many challenges; for example, (1) the device mechanisms including the charge injection/transport/leakage, exciton quenching, and device degradation are still unclear, which fundamentally limit QLED performance improvement; (2) the blue performances including the efficiency, chromaticity, and stability are relatively low, which are still far from the requirements of practical applications; (3) the color patterning processes including the ink-jet printing, transfer printing, and photolithography are still immature, which restrict the manufacturing of high resolution full-color QLED displays. Here, the recent advancements attempting to address the above challenges of QLED displays are specifically reviewed. After a brief overview of QLED development history, device structure/principle, and performances, the main focus is to investigate the recent discoveries on device mechanisms with an emphasis on device degradation. Then recent progress is introduced in blue QLEDs and color patterning. Finally, the opportunities, challenges, solutions, and future research directions of QLED displays are summarized.
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Affiliation(s)
- Zinan Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Haotao Li
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Cuixia Yuan
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Peili Gao
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Qiang Su
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Shuming Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
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10
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Gao P, Chen Z, Chen S. Electron-Induced Degradation in Blue Quantum-Dot Light-Emitting Diodes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2309123. [PMID: 38038258 DOI: 10.1002/adma.202309123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/15/2023] [Indexed: 12/02/2023]
Abstract
The poor stability of blue quantum-dot (QD) light-emitting diodes (B-QLEDs) hinders their application in displays. To improve the stability of B-QLEDs, the degradation mechanism should be revealed. Here, the degradation mechanism of B-QLEDs is investigated by monitoring the changes occurring in the QDs and the hole transport layers (HTL) during device operation, respectively. It is revealed that the accumulation of electrons within the QDs is responsible for the degradation of the devices. On the one hand, the accumulated electrons induce the detachment of oleic acid ligands, leading to permanent damage to the stability of B-QDs. On the other hand, the accumulated electrons leak into the HTL or recombine at the HTL/QDs interface, leading to the degradation of HTL. The formation of surface defects in B-QDs and the decomposition of HTL contribute to the degradation of B-QLEDs. The results reveal the strong dependence of B-QLEDs stability on the accumulated electrons, the QDs and the HTL, which can help researchers to develop effective design strategies for improving the lifespan of B-QLEDs.
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Affiliation(s)
- Peili Gao
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Zinan Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Shuming Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
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11
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Li M, Zhang X, Bao H, Yan Y, Wu XG, Wang C, Cao Y, Yang M, Chen C, Hu X, Hou W, Cao W, Zhong H. The warming-up effects of quantum-dot light emitting diodes: A reversible stability issue related to shell traps. J Chem Phys 2024; 160:044704. [PMID: 38265088 DOI: 10.1063/5.0185626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 01/01/2024] [Indexed: 01/25/2024] Open
Abstract
The aging phenomenon is commonly observed in quantum-dot light emitting diodes (QLEDs), involving complex chemical or physical processes. Resolving the underlying mechanism of these aging issues is crucial to deliver reliable electroluminescent devices in future display applications. Here, we report a reversible positive aging phenomenon that the device brightness and efficiency significantly improve after device operation, but recover to initial states after long-time storage or mild heat treatment, which can be termed as warming-up effects. Steady and transient equivalent circuit analysis suggest that the radiative recombination current dramatically increases but electron leakage from the quantum dots (QDs) to hole transport layer becomes more accessible during the warming-up process. Further analysis discloses that the notable enhancement of device efficiency can be ascribed to the filling of shell traps in gradient alloyed QDs. This work reveals a distinct positive aging phenomenon featured with reversibility, and further guidelines would be provided to achieve stable QLED devices in real display applications.
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Affiliation(s)
- Menglin Li
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Sciences and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Xin Zhang
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Sciences and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Hui Bao
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Sciences and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Yiran Yan
- TCL Corporate Research, Shenzhen, Guangdong 518067, China
| | - Xian-Gang Wu
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Sciences and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Cheng Wang
- TCL Corporate Research, Shenzhen, Guangdong 518067, China
| | - Yongqi Cao
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Sciences and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Min Yang
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Sciences and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Cuili Chen
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Sciences and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Xiangmin Hu
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Sciences and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Wenjun Hou
- TCL Corporate Research, Shenzhen, Guangdong 518067, China
| | - Weiran Cao
- TCL Corporate Research, Shenzhen, Guangdong 518067, China
| | - Haizheng Zhong
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Sciences and Engineering, Beijing Institute of Technology, Beijing 100081, China
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12
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Azadinia M, Chun P, Lyu Q, Cotella G, Aziz H. Differences in Electron and Hole Injection and Auger Recombination between Red, Green, and Blue CdSe-Based Quantum Dot Light Emitting Devices. ACS NANO 2024; 18:1485-1495. [PMID: 38175971 DOI: 10.1021/acsnano.3c07999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
Despite the significant progress that has been made in recent years in improving the performance of quantum dot light-emitting devices (QLEDs), the effect of charge imbalance and excess carriers on excitons in red (R) vs green (G) vs blue (B) QLEDs has not been compared or systematically studied. In this work we study the effect of changing the electron (e)/hole (h) supply ratio in the QDs emissive layer (EML) in CdSe-based R-, G-, and B-QLEDs with inverted structure in order to identify the type of excess carriers and investigate their effect on the electroluminescence performance of QLEDs of each color. Results show that in R-QLEDs, the e/h ratio in the EML is >1, whereas in G- and B-QLEDs, the e/h ratio is <1 with charge balance conditions being significantly worse in the case of B-QLEDs. Transient photoluminescence (PL) and steady state PL measurements show that, compared to electrons, holes lead to a stronger Auger quenching effect. Transient electroluminescence (TrEL) results indicate that Auger quenching leads to a gradual decline in the EL performance of the QLEDs after a few microseconds, with a stronger effect observed for positive charging versus negative charging. The results provide insights into the differences in the efficiency behavior of R-, G-, and B-QLEDs and uncover the role of excess holes and poor charge balance in the lower efficiency and EL stability of B-QLEDs.
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Affiliation(s)
- Mohsen Azadinia
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Peter Chun
- Ottawa IC Laboratory, Huawei Canada, 19 Allstate Parkway, Markham, Ontario L3R 5B4, Canada
| | - Quan Lyu
- Ipswich Research Centre, Huawei Technologies Research & Development (U.K.) Ltd., Phoenix House (B55), Adastral Park, Ipswich, IP5 3RE, U.K
| | - Giovanni Cotella
- Ipswich Research Centre, Huawei Technologies Research & Development (U.K.) Ltd., Phoenix House (B55), Adastral Park, Ipswich, IP5 3RE, U.K
| | - Hany Aziz
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
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13
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Cao Z, Li C, Shu Y, Zhu M, Su B, Qin H, Peng X. Unraveling Mechanisms of Highly Efficient Yet Stable Electrochemiluminescence from Quantum Dots. J Am Chem Soc 2023; 145:26425-26434. [PMID: 37976033 DOI: 10.1021/jacs.3c10556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
With CdSe/CdS/ZnS core/shell/shell quantum dots (QDs) as the model system, time- and potential-resolved spectroelectrochemical measurements are successfully applied for studying the general mechanisms and kinetics of electrochemiluminescence (ECL) generation. The rate constant of electron injection from the cathode into a QD to form a negatively charged QD (QD-) increases monotonically from -0.88 V to -1.2 V (vs Ag/AgCl). Mainly due to the deep LUMO of the QDs, the resulting QD- as the key intermediate for ECL generation is structurally stable and possesses very slow spontaneous deionization channels. The latter (the main non-ECL channels) are usually 3-4 orders of magnitude slower than the rate constant of the successive hole injection from an active co-reactant into a QD-. The kinetic studies quantify the internal ECL quantum yield of ideal QD ECL emitters to be nearly identical to that of photoluminescence, which is near unity for the current system. Identification of the key intermediate, discovery of the related elementary steps, and determination of all rate constants not only establish a general framework for understanding ECL generation but also offer basic design rules for ECL emitters.
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Affiliation(s)
- Zhiyuan Cao
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Chuyue Li
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Yufei Shu
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Meiyi Zhu
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Bin Su
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Haiyan Qin
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Xiaogang Peng
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
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14
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He S, Tang X, Deng Y, Yin N, Jin W, Lu X, Chen D, Wang C, Sun T, Chen Q, Jin Y. Anomalous efficiency elevation of quantum-dot light-emitting diodes induced by operational degradation. Nat Commun 2023; 14:7785. [PMID: 38012136 PMCID: PMC10682488 DOI: 10.1038/s41467-023-43340-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Accepted: 11/08/2023] [Indexed: 11/29/2023] Open
Abstract
Quantum-dot light-emitting diodes promise a new generation of high-performance and solution-processed electroluminescent light sources. Understanding the operational degradation mechanisms of quantum-dot light-emitting diodes is crucial for their practical applications. Here, we show that quantum-dot light-emitting diodes may exhibit an anomalous degradation pattern characterized by a continuous increase in electroluminescent efficiency upon electrical stressing, which deviates from the typical decrease in electroluminescent efficiency observed in other light-emitting diodes. Various in-situ/operando characterizations were performed to investigate the evolutions of charge dynamics during the efficiency elevation, and the alterations in electric potential landscapes in the active devices. Furthermore, we carried out selective peel-off-and-rebuild experiments and depth-profiling analyses to pinpoint the critical degradation site and reveal the underlying microscopic mechanism. The results indicate that the operation-induced efficiency increase results from the degradation of electron-injection capability at the electron-transport layer/cathode interface, which in turn leads to gradually improved charge balance. Our work provides new insights into the degradation of red quantum-dot light-emitting diodes and has far-reaching implications for the design of charge-injection interfaces in solution-processed light-emitting diodes.
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Affiliation(s)
- Siyu He
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou, China
| | - Xiaoqi Tang
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou, China
| | - Yunzhou Deng
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, China.
- Cavendish Laboratory, University of Cambridge, Cambridge, UK.
| | - Ni Yin
- i-Lab, CAS Key Laboratory of Nanophotonic Materials and Devices, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, China
| | - Wangxiao Jin
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou, China
| | - Xiuyuan Lu
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou, China
| | - Desui Chen
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou, China
| | - Chenyang Wang
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou, China
| | - Tulai Sun
- Center for Electron Microscopy, State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology and College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, China
| | - Qi Chen
- i-Lab, CAS Key Laboratory of Nanophotonic Materials and Devices, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, China.
| | - Yizheng Jin
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou, China.
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15
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Rahman IKMR, Uddin SZ, Yeh M, Higashitarumizu N, Kim J, Li Q, Lee H, Lee K, Kim H, Park C, Lim J, Ager JW, Javey A. Gate Controlled Excitonic Emission in Quantum Dot Thin Films. NANO LETTERS 2023; 23:10164-10170. [PMID: 37934978 DOI: 10.1021/acs.nanolett.3c02456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
Formation of charged trions is detrimental to the luminescence quantum efficiency of colloidal quantum dot (QD) thin films as they predominantly undergo nonradiative recombination. In this regard, control of charged trion formation is of interest for both fundamental characterization of the quasi-particles and performance optimization. Using CdSe/CdS QDs as a prototypical material system, here we demonstrate a metal-oxide-semiconductor capacitor based on QD thin films for studying the background charge effect on the luminescence efficiency and lifetime. The concentration ratio of the charged and neutral quasiparticles in the QDs is reversibly controlled by applying a gate voltage, while simultaneous steady-state and time-resolved photoluminescence measurements are performed. Notably, the photoluminescence intensity is modulated by up to 2 orders of magnitude with a corresponding change in the effective lifetime. In addition, chip-scale modulation of brightness is demonstrated, where the photoluminescence is effectively turned on and off by the gate, highlighting potential applications in voltage-controlled electrochromics.
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Affiliation(s)
- I K M Reaz Rahman
- Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Shiekh Zia Uddin
- Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Matthew Yeh
- Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Naoki Higashitarumizu
- Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jongchan Kim
- Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Quanwei Li
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Kavli Energy Nanoscience Institute at Berkeley, Berkeley, California 94720, United States
| | - Hyeonjun Lee
- Department of Energy Science and Centre for Artificial Atoms, Sungkyunkwan University, Natural Sciences Campus, Seobu-ro 2066, Jangan-gu, Suwon 16419, Gyeonggi-do, Republic of Korea
| | - Kyuho Lee
- Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - HoYeon Kim
- Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Cheolmin Park
- Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Jaehoon Lim
- Department of Energy Science and Centre for Artificial Atoms, Sungkyunkwan University, Natural Sciences Campus, Seobu-ro 2066, Jangan-gu, Suwon 16419, Gyeonggi-do, Republic of Korea
| | - Joel W Ager
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Materials Science and Engineering, University of California, Berkeley, California 94720, United States
| | - Ali Javey
- Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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16
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Samaeifar F, Azadinia M, Aziz H. Lifetime enhancement in QDLEDs via an electron-blocking hole transport layer. Sci Rep 2023; 13:18698. [PMID: 37907631 PMCID: PMC10618160 DOI: 10.1038/s41598-023-45907-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 10/25/2023] [Indexed: 11/02/2023] Open
Abstract
This study investigates the impact of an engineered hole transport layer (HTL) on the stability of electroluminescent quantum dot light-emitting devices (QDLEDs). The 9-Phenyl-3,6-bis(9-phenyl-9Hcarbazol-3-yl)-9H-carbazole (Tris-PCz) HTL, which possesses a shallower lowest unoccupied molecular orbital (LUMO) energy level compared to the widely used 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) HTL, is employed to confine electron overflow toward the HTL. Utilizing the Tris-PCz HTL results in a 20× improvement in the electroluminescence half-life (LT50) of QDLEDs compared with conventional QDLEDs using the CBP HTL. Electric and optoelectronic analyses reveal that the migration of excess electrons toward the HTL is impeded by the up-shifted LUMO level of Tris-PCz, contributing to prolonged operational device stability. Furthermore, the augmented electric field at the QD/Tris-PCz interface, due to accumulated electrons, expedites hole injection rates, leading to better charge injection balance and the confinement of the exciton recombination zone within the QD and thus the device stability enhancement. This study highlights the significant influence of the HTL on QDLED stability and represents one of the longest LT50 for a QDLED based on the conventional core/shell QD structure.
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Affiliation(s)
- Fatemeh Samaeifar
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada.
| | - Mohsen Azadinia
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
| | - Hany Aziz
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
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17
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He J, Ge Y, Wang Y, Yuan M, Xia H, Zhang X, Chen X, Wang X, Zhou X, Li K, Chen C, Tang J. Fluoride passivation of ZnO electron transport layers for efficient PbSe colloidal quantum dot photovoltaics. FRONTIERS OF OPTOELECTRONICS 2023; 16:28. [PMID: 37889375 PMCID: PMC10611680 DOI: 10.1007/s12200-023-00082-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 09/08/2023] [Indexed: 10/28/2023]
Abstract
Lead selenide (PbSe) colloidal quantum dots (CQDs) are suitable for the development of the next-generation of photovoltaics (PVs) because of efficient multiple-exciton generation and strong charge coupling ability. To date, the reported high-efficient PbSe CQD PVs use spin-coated zinc oxide (ZnO) as the electron transport layer (ETL). However, it is found that the surface defects of ZnO present a difficulty in completion of passivation, and this impedes the continuous progress of devices. To address this disadvantage, fluoride (F) anions are employed for the surface passivation of ZnO through a chemical bath deposition method (CBD). The F-passivated ZnO ETL possesses decreased densities of oxygen vacancy and a favorable band alignment. Benefiting from these improvements, PbSe CQD PVs report an efficiency of 10.04%, comparatively 9.4% higher than that of devices using sol-gel (SG) ZnO as ETL. We are optimistic that this interface passivation strategy has great potential in the development of solution-processed CQD optoelectronic devices.
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Affiliation(s)
- Jungang He
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, Hubei Engineering Technology Research Center of Optoelectronic and New Energy Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, China.
- Wuhan National Laboratory for Optoelectronics (WNLO), School of Optical and Electronic Information, School of Integrated Circuits, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - You Ge
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, Hubei Engineering Technology Research Center of Optoelectronic and New Energy Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, China
| | - Ya Wang
- Wuhan National Laboratory for Optoelectronics (WNLO), School of Optical and Electronic Information, School of Integrated Circuits, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Mohan Yuan
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, Hubei Engineering Technology Research Center of Optoelectronic and New Energy Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, China
| | - Hang Xia
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, Hubei Engineering Technology Research Center of Optoelectronic and New Energy Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, China
| | - Xingchen Zhang
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, Hubei Engineering Technology Research Center of Optoelectronic and New Energy Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, China
| | - Xiao Chen
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, Hubei Engineering Technology Research Center of Optoelectronic and New Energy Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, China
| | - Xia Wang
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, Hubei Engineering Technology Research Center of Optoelectronic and New Energy Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, China
| | - Xianchang Zhou
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, Hubei Engineering Technology Research Center of Optoelectronic and New Energy Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, China
| | - Kanghua Li
- Wuhan National Laboratory for Optoelectronics (WNLO), School of Optical and Electronic Information, School of Integrated Circuits, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - Chao Chen
- Wuhan National Laboratory for Optoelectronics (WNLO), School of Optical and Electronic Information, School of Integrated Circuits, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Jiang Tang
- Wuhan National Laboratory for Optoelectronics (WNLO), School of Optical and Electronic Information, School of Integrated Circuits, Huazhong University of Science and Technology, Wuhan, 430074, China
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18
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Liang X, Durmusoglu EG, Lunina M, Hernandez-Martinez PL, Valuckas V, Yan F, Lekina Y, Sharma VK, Yin T, Ha ST, Shen ZX, Sun H, Kuznetsov A, Demir HV. Near-Unity Emitting, Widely Tailorable, and Stable Exciton Concentrators Built from Doubly Gradient 2D Semiconductor Nanoplatelets. ACS NANO 2023; 17:19981-19992. [PMID: 37610378 PMCID: PMC10603796 DOI: 10.1021/acsnano.3c05125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 08/11/2023] [Indexed: 08/24/2023]
Abstract
The strength of electrostatic interactions (EIs) between electrons and holes within semiconductor nanocrystals profoundly affects the performance of their optoelectronic systems, and different optoelectronic devices demand distinct EI strength of the active medium. However, achieving a broad range and fine-tuning of the EI strength for specific optoelectronic applications is a daunting challenge, especially in quasi two-dimensional core-shell semiconductor nanoplatelets (NPLs), as the epitaxial growth of the inorganic shell along the direction of the thickness that solely contributes to the quantum confined effect significantly undermines the strength of the EI. Herein we propose and demonstrate a doubly gradient (DG) core-shell architecture of semiconductor NPLs for on-demand tailoring of the EI strength by controlling the localized exciton concentration via in-plane architectural modulation, demonstrated by a wide tuning of radiative recombination rate and exciton binding energy. Moreover, these exciton-concentration-engineered DG NPLs also exhibit a near-unity quantum yield, high photo- and thermal stability, and considerably suppressed self-absorption. As proof-of-concept demonstrations, highly efficient color converters and high-performance light-emitting diodes (external quantum efficiency: 16.9%, maximum luminance: 43,000 cd/m2) have been achieved based on the DG NPLs. This work thus provides insights into the development of high-performance colloidal optoelectronic device applications.
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Affiliation(s)
- Xiao Liang
- LUMINOUS!
Center of Excellence for Semiconductor Lighting and Displays, The
Photonics Institute, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Emek G. Durmusoglu
- LUMINOUS!
Center of Excellence for Semiconductor Lighting and Displays, The
Photonics Institute, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- Division
of Physics and Applied Physics, School of Physical and Mathematical
Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Maria Lunina
- Interdisciplinary
Graduate Program, Nanyang Technological
University, Singapore, 637371, Singapore
| | - Pedro Ludwig Hernandez-Martinez
- LUMINOUS!
Center of Excellence for Semiconductor Lighting and Displays, The
Photonics Institute, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Vytautas Valuckas
- Institute
of Materials Research and Engineering, A*STAR (Agency for Science,
Technology and Research), 2 Fusionopolis Way, #08-03 Innovis, Singapore, 138634, Singapore
| | - Fei Yan
- LUMINOUS!
Center of Excellence for Semiconductor Lighting and Displays, The
Photonics Institute, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Yulia Lekina
- Division
of Physics and Applied Physics, School of Physical and Mathematical
Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Vijay Kumar Sharma
- LUMINOUS!
Center of Excellence for Semiconductor Lighting and Displays, The
Photonics Institute, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Tingting Yin
- Division
of Physics and Applied Physics, School of Physical and Mathematical
Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Son Tung Ha
- Institute
of Materials Research and Engineering, A*STAR (Agency for Science,
Technology and Research), 2 Fusionopolis Way, #08-03 Innovis, Singapore, 138634, Singapore
| | - Ze Xiang Shen
- Division
of Physics and Applied Physics, School of Physical and Mathematical
Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Handong Sun
- Division
of Physics and Applied Physics, School of Physical and Mathematical
Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Arseniy Kuznetsov
- Institute
of Materials Research and Engineering, A*STAR (Agency for Science,
Technology and Research), 2 Fusionopolis Way, #08-03 Innovis, Singapore, 138634, Singapore
| | - Hilmi Volkan Demir
- LUMINOUS!
Center of Excellence for Semiconductor Lighting and Displays, The
Photonics Institute, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- Division
of Physics and Applied Physics, School of Physical and Mathematical
Sciences, Nanyang Technological University, Singapore, 637371, Singapore
- UNAM—Institute
of Materials Science and Nanotechnology, The National Nanotechnology
Research Center, Department of Electrical and Electronics Engineering,
Department of Physics, Bilkent University, Bilkent, Ankara 06800,Turkey
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19
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Wang YK, Jia F, Li X, Teale S, Xia P, Liu Y, Chan PTS, Wan H, Hassan Y, Imran M, Chen H, Grater L, Sun LD, Walker GC, Hoogland S, Lu ZH, Yan CH, Liao LS, Sargent EH. Self-assembled monolayer-based blue perovskite LEDs. SCIENCE ADVANCES 2023; 9:eadh2140. [PMID: 37683007 PMCID: PMC10491221 DOI: 10.1126/sciadv.adh2140] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 08/09/2023] [Indexed: 09/10/2023]
Abstract
Blue perovskite light-emitting diodes (LEDs) have shown external quantum efficiencies (EQEs) of more than 10%; however, devices that emit in the true blue-those that accord with the emission wavelength required for Rec. 2100 primary blue-have so far been limited to EQEs of ~6%. We focused here on true blue emitting CsPbBr3 colloidal nanocrystals (c-NCs), finding in early studies that they suffer from a high charge injection barrier, a problem exacerbated in films containing multiple layers of nanocrystals. We introduce a self-assembled monolayer (SAM) active layer that improves charge injection. We identified a bifunctional capping ligand that simultaneously enables the self-assembly of CsPbBr3 c-NCs while passivating surface traps. We report, as a result, SAM-based LEDs exhibit a champion EQE of ~12% [CIE of (0.132, 0.069) at 4.0 V with a luminance of 11 cd/m2], and 10-fold-enhanced operating stability relative to the best previously reported Rec. 2100-blue perovskite LEDs.
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Affiliation(s)
- Ya-Kun Wang
- Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, PR China
| | - Fengyan Jia
- Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Xiaoyue Li
- Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4, Canada
| | - Sam Teale
- Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
| | - Pan Xia
- Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
| | - Yuan Liu
- Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
| | - Phoebe Tsz-shan Chan
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Haoyue Wan
- Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
| | - Yasser Hassan
- Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
- Department of Chemistry and Earth Sciences, College of Arts and Sciences, Qatar University, P.O. Box: 2713, Doha, Qatar
| | - Muhammad Imran
- Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
| | - Hao Chen
- Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
| | - Luke Grater
- Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
| | - Ling-Dong Sun
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Gilbert C. Walker
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Sjoerd Hoogland
- Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
| | - Zheng-Hong Lu
- Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4, Canada
| | - Chun-Hua Yan
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Liang-Sheng Liao
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, PR China
| | - Edward H. Sargent
- Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
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20
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Mokarian Zanjani S, Sadeghi S, Shahalizad A, Pahlevani M. An investigation on the cyclic temperature-dependent performance behaviors of ultrabright air-stable QLEDs. Sci Rep 2023; 13:12713. [PMID: 37543660 PMCID: PMC10404233 DOI: 10.1038/s41598-023-39952-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 08/02/2023] [Indexed: 08/07/2023] Open
Abstract
The aerobic and thermal stability of quantum-dot light-emitting diodes (QLEDs) is an important factor for the practical applications of these devices under harsh environmental conditions. We demonstrate all-solution-processed amber QLEDs with an external quantum efficiency (EQE) of > 14% with almost negligible efficiency roll-off (droop) and a peak brightness of > 600,000 cd/m2, unprecedented for QLEDs fabricated under ambient air conditions. We investigate the device efficiency and brightness level at a temperature range between - 10 and 85 °C in a 5-step cooling/heating cycle. We conducted the experiments at brightness levels higher than 10,000 cd/m2, required for outdoor lighting applications. Our device performance proves thermal stability, with minimal standard deviation in the performance parameters. Interestingly, the device efficiency parameters recover to the initial values upon returning to room temperature. The variations in the performance are correlated with the modification of charge transport characteristics and induced radiative/non-radiative exciton relaxation dynamics at different temperatures. Being complementary to previous studies on the subject, the present work is expected to shed light on the potential feasibility of realizing aerobic-stable ultrabright droop-free QLEDs and encourage further research for solid-state lighting applications.
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Affiliation(s)
- Saeedeh Mokarian Zanjani
- Department of Electrical and Computer Engineering, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Sadra Sadeghi
- Department of Electrical and Computer Engineering, Queen's University, Kingston, ON, K7L 3N6, Canada
| | | | - Majid Pahlevani
- Department of Electrical and Computer Engineering, Queen's University, Kingston, ON, K7L 3N6, Canada.
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21
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Lin Q, Zhu Y, Wang Y, Li D, Zhao Y, Liu Y, Li F, Huang W. Flexible Quantum Dot Light-Emitting Device for Emerging Multifunctional and Smart Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2210385. [PMID: 36880739 DOI: 10.1002/adma.202210385] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 02/13/2023] [Indexed: 06/18/2023]
Abstract
Quantum dot light-emitting diodes (QLEDs), owing to their exceptional performances in device efficiency, color purity/tunability in the visible region and solution-processing ability on various substrates, become a potential candidate for flexible and ultrathin electroluminescent (EL) lighting and display. Moreover, beyond the lighting and display, flexible QLEDs are enabled with endless possibilities in the era of the internet of things and artificial intelligence by acting as input/output ports in wearable integrated systems. Challenges remain in the development of flexible QLEDs with the goals for high performance, excellent flexibility/even stretchability, and emerging applications. In this paper, the recent developments of QLEDs including quantum dot materials, working mechanism, flexible/stretchable strategies and patterning strategies, and highlight its emerging multifunctional integrations and smart applications covering wearable optical medical devices, pressure-sensing EL devices, and neural smart EL devices, are reviewed. The remaining challenges are also summarized and an outlook on the future development of flexible QLEDs made. The review is expected to offer a systematic understanding and valuable inspiration for flexible QLEDs to simultaneously satisfy optoelectronic and flexible properties for emerging applications.
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Affiliation(s)
- Qinghong Lin
- Strait Institute of Flexible Electronics (SIFE, Future Technologies), Fujian Normal University, Fuzhou, Fujian, 350117, P. R. China
- Strait Laboratory of Flexible Electronics (SLoFE), Fuzhou, Fujian, 350117, P. R. China
| | - Yangbin Zhu
- School of Intelligent Manufacturing and Electronic Engineering, Wenzhou University of Technology, Wenzhou, 325035, P. R. China
| | - Yue Wang
- Strait Institute of Flexible Electronics (SIFE, Future Technologies), Fujian Normal University, Fuzhou, Fujian, 350117, P. R. China
- Strait Laboratory of Flexible Electronics (SLoFE), Fuzhou, Fujian, 350117, P. R. China
| | - Deli Li
- Strait Institute of Flexible Electronics (SIFE, Future Technologies), Fujian Normal University, Fuzhou, Fujian, 350117, P. R. China
- Strait Laboratory of Flexible Electronics (SLoFE), Fuzhou, Fujian, 350117, P. R. China
| | - Yi Zhao
- Strait Institute of Flexible Electronics (SIFE, Future Technologies), Fujian Normal University, Fuzhou, Fujian, 350117, P. R. China
- Strait Laboratory of Flexible Electronics (SLoFE), Fuzhou, Fujian, 350117, P. R. China
| | - Yang Liu
- Strait Institute of Flexible Electronics (SIFE, Future Technologies), Fujian Normal University, Fuzhou, Fujian, 350117, P. R. China
- Strait Laboratory of Flexible Electronics (SLoFE), Fuzhou, Fujian, 350117, P. R. China
| | - Fushan Li
- Institute of Optoelectronic Technology, Fuzhou University, Fuzhou, 350116, P. R. China
| | - Wei Huang
- Strait Institute of Flexible Electronics (SIFE, Future Technologies), Fujian Normal University, Fuzhou, Fujian, 350117, P. R. China
- Strait Laboratory of Flexible Electronics (SLoFE), Fuzhou, Fujian, 350117, P. R. China
- Frontiers Science Center for Flexible Electronics (FSCFE), MIIT Key Laboratory of Flexible Electronics (KLoFE), Northwestern Polytechnical University (NPU), Xi'an, 710072, P. R. China
- Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, 211816, P. R. China
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22
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Abstract
Lasers and optical amplifiers based on solution-processable materials have been long-desired devices for their compatibility with virtually any substrate, scalability, and ease of integration with on-chip photonics and electronics. These devices have been pursued across a wide range of materials including polymers, small molecules, perovskites, and chemically prepared colloidal semiconductor nanocrystals, also commonly referred to as colloidal quantum dots. The latter materials are especially attractive for implementing optical-gain media as in addition to being compatible with inexpensive and easily scalable chemical techniques, they offer multiple advantages derived from a zero-dimensional character of their electronic states. These include a size-tunable emission wavelength, low optical gain thresholds, and weak sensitivity of lasing characteristics to variations in temperature. Here we review the status of colloidal nanocrystal lasing devices, most recent advances in this field, outstanding challenges, and the ongoing progress toward technological viable devices including colloidal quantum dot laser diodes.
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Affiliation(s)
- Namyoung Ahn
- Nanotechnology and Advanced Spectroscopy Team, C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Clément Livache
- Nanotechnology and Advanced Spectroscopy Team, C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Valerio Pinchetti
- Nanotechnology and Advanced Spectroscopy Team, C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Victor I Klimov
- Nanotechnology and Advanced Spectroscopy Team, C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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23
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Tang X, He S, Deng Y, Lu X, Zhu X, Jin W, Jin Y. Mg-Diffusion of ZnO-Based Electron-Transport Layers for Highly Conductive Quantum-Dot Light-Emitting Diodes. J Phys Chem Lett 2023:5812-5817. [PMID: 37338303 DOI: 10.1021/acs.jpclett.3c01465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023]
Abstract
Quantum-dot light-emitting diodes (QLEDs) show great potential in next-generation display and lighting technologies. Further reducing the resistances of the high-efficiency QLEDs is critical to improving their luminous efficiencies and lowering their power consumption. However, wet-chemistry methods to improve the conductivities of ZnO-based electron-transport layers (ETLs) often lead to trade-offs in the external quantum efficiencies (EQEs) of QLEDs. Here, we report a facile approach toward highly conductive QLEDs by in situ diffusion of Mg atoms into the ZnO-based ETLs. We demonstrate that thermally evaporated Mg can spread deep into the ZnO-based ETL with a long penetration length, generating oxygen vacancies that promote the electron-transport properties. The Mg-diffused ETLs enhance the conductivities and luminous efficiencies of state-of-the-art QLEDs without sacrificing the EQEs. This strategy is applied to QLEDs with various optical architectures, leading to significant enhancements in the current densities, luminances, and luminous efficiencies. We expect that our method could be extended to other solution-processed LEDs using ZnO-based ETLs.
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Affiliation(s)
- Xiaoqi Tang
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon and Advanced Semiconductor Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Siyu He
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon and Advanced Semiconductor Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Yunzhou Deng
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, 310027, Hangzhou, China
- Cavendish Laboratory, University of Cambridge, CB3 0HE, Cambridge, United Kingdom
| | - Xiuyuan Lu
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon and Advanced Semiconductor Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Xitong Zhu
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon and Advanced Semiconductor Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Wangxiao Jin
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon and Advanced Semiconductor Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Yizheng Jin
- Key Laboratory of Excited-State Materials of Zhejiang Province, State Key Laboratory of Silicon and Advanced Semiconductor Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
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24
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Yu R, Yin F, Pu C, Zhou D, Ji W. On the electroluminescence overshoot of quantum-dot light-emitting diodes. OPTICS LETTERS 2023; 48:3059-3062. [PMID: 37262280 DOI: 10.1364/ol.492710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 05/15/2023] [Indexed: 06/03/2023]
Abstract
The charge-carrier dynamics is a fundamental question in quantum-dot light-emitting diodes (QLEDs), determining the electroluminescence (EL) properties of the devices. By means of a hole-confined QLED design, the distribution and storage/residing of the charge carriers in the devices are deciphered by the transient electroluminescence (TrEL) spectroscopic technology. It is demonstrated that the holes stored in the quantum dots (QDs) are responsible for the EL overshoot during the rising edge of the TrEL response. Moreover, the earlier electroluminescence turn-on behavior is observed due to the holes residing in the hole-confined structure. The hole storage effect should be attributed to the ultralow hole mobility of QD films and large barrier for hole escape from the cores of the QDs. Our findings provide a deep understanding of the charge transport and storage at the most critical interface between QDs and hole-transport layer, where the excitons are formed.
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25
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Xu Q, Yang X, Liu JJ, Li F, Chang R, Wang L, Wang AQ, Wu Z, Shen H, Du Z. Elaborating the interplay between the detecting unit and emitting unit in infrared quantum dot up-conversion photodetectors. NANOSCALE 2023; 15:8197-8203. [PMID: 37097127 DOI: 10.1039/d3nr01237a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The quantum dot up-conversion device combines an infrared photodetector (PD) and a visible quantum-dot light-emitting diode (QLED) to directly convert infrared targets to visible images. However, large efficiency loss is usually induced by the integration of the detecting unit and the emitting unit. One of the important reasons is the performances of the PD and QLED units restraining each other. We regulated the equilibrium between infrared absorption and visible emission by changing the thicknesses of infrared active layers in up-conversion devices. A good balance could be achieved between the absorption of 980 nm incident light and the out-coupling of the 634 nm emission when the active layer thickness is 140 nm, leading to the best performance of the up-conversion device. As more photogenerated carriers are produced with the increase of infrared illumination intensity, the external quantum efficiency (EQE) of the QLED unit in the up-conversion device remains little changed. This suggests the limited amount of photogenerated holes in the PD unit does not limit the EQE of the QLED unit. However, a PD unit with a high ratio of photogenerated holes trapped near the interconnection decreased the EQE in the QLED unit. This work provides new insights into the interplay between the PD and QLED units in up-conversion devices, which is crucial for their further improvements.
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Affiliation(s)
- Qiulei Xu
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials and Engineering, Henan University, Kaifeng 475004, China.
| | - Xinxin Yang
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials and Engineering, Henan University, Kaifeng 475004, China.
| | - Jiao Jiao Liu
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials and Engineering, Henan University, Kaifeng 475004, China.
| | - Fei Li
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials and Engineering, Henan University, Kaifeng 475004, China.
| | - Ruiguang Chang
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials and Engineering, Henan University, Kaifeng 475004, China.
| | - Lei Wang
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials and Engineering, Henan University, Kaifeng 475004, China.
| | - A Qiang Wang
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials and Engineering, Henan University, Kaifeng 475004, China.
| | - Zhenghui Wu
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials and Engineering, Henan University, Kaifeng 475004, China.
| | - Huaibin Shen
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials and Engineering, Henan University, Kaifeng 475004, China.
| | - Zuliang Du
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials and Engineering, Henan University, Kaifeng 475004, China.
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26
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Zhang X, Bao H, Chen C, Wu XG, Li M, Ji W, Wang S, Zhong H. The fatigue effects in red emissive CdSe based QLED operated around turn-on voltage. J Chem Phys 2023; 158:131101. [PMID: 37031138 DOI: 10.1063/5.0145471] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023] Open
Abstract
The operational stability is a current bottleneck facing the quantum dot light-emitting diodes (QLEDs). In particular, the device working around turn-on voltage suffers from unbalanced charge injection and heavy power loss. Here, we investigate the operational stability of red emissive CdSe QLEDs operated at different applied voltages. Compared to the rising luminance at higher voltages, the device luminance quickly decreases when loaded around the turn-on voltage, but recovers after unloading or slight heat treatment, which is termed fatigue effects of operational QLED. The electroluminescence and photoluminescence spectra before and after a period of operation at low voltages show that the abrupt decrease in device luminance derives from the reduction of quantum yield in quantum dots. Combined with transient photoluminescence and electroluminescence measurements, as well as equivalent circuit model analysis, the electron accumulation in quantum dots mainly accounts for the observed fatigue effects of a QLED during the operation around turn-on voltage. The underlying mechanisms at the low-voltage working regime will be very helpful for the industrialization of QLED.
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Affiliation(s)
- Xin Zhang
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Hui Bao
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Cuili Chen
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Xian-gang Wu
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Menglin Li
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Wenyu Ji
- Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, Changchun 130012, China
| | - Shuangpeng Wang
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macao SAR, 999078, China
| | - Haizheng Zhong
- MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
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27
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Chen D, Ma L, Chen Y, Zhou X, Xing S, Deng Y, Hao Y, Pu C, Kong X, Jin Y. Electrochemically Stable Ligands of ZnO Electron-Transporting Layers for Quantum-Dot Light-Emitting Diodes. NANO LETTERS 2023; 23:1061-1067. [PMID: 36662173 DOI: 10.1021/acs.nanolett.2c04670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Thin films of ZnO nanocrystals are actively pursued as electron-transporting layers (ETLs) in quantum-dot light-emitting diodes (QLEDs). However, the developments of ZnO-based ETLs are highly engineering oriented and the design of ZnO-based ETLs remains empirical. Here, we identified a previously overlooked efficiency-loss channel associated with the ZnO-based ETLs: i.e., interfacial exciton quenching induced by surface-bound ethanol. Accordingly, we developed a general surface-treatment procedure to replace the redox-active surface-bound ethanol with electrochemically inert alkali carboxylates. Characterization results show that the surface treatment procedure does not change other key properties of the ETLs, such as the conductance and work function. Our single-variable experimental design unambiguously demonstrates that improving the electrochemical stabilities of the ZnO ETLs leads to QLEDs with a higher efficiency and longer operational lifetime. Our work provides a crucial guideline to design ZnO-based ETLs for optoelectronic devices.
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Affiliation(s)
- Desui Chen
- Zhejiang Key Laboratory for Excited-State Materials, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Luying Ma
- Zhejiang Key Laboratory for Excited-State Materials, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Yunhua Chen
- Zhejiang Key Laboratory for Excited-State Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Xiaoqi Zhou
- Zhejiang Key Laboratory for Excited-State Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Shiyu Xing
- Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Yunzhou Deng
- Zhejiang Key Laboratory for Excited-State Materials, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Yanlei Hao
- Zhejiang Key Laboratory for Excited-State Materials, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Chaodan Pu
- School of Physical Science and Technology, Shanghai Tech University, Shanghai 201210, People's Republic of China
| | - Xueqian Kong
- Zhejiang Key Laboratory for Excited-State Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Yizheng Jin
- Zhejiang Key Laboratory for Excited-State Materials, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, People's Republic of China
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28
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Chen X, Lin X, Zhou L, Sun X, Li R, Chen M, Yang Y, Hou W, Wu L, Cao W, Zhang X, Yan X, Chen S. Blue light-emitting diodes based on colloidal quantum dots with reduced surface-bulk coupling. Nat Commun 2023; 14:284. [PMID: 36650161 PMCID: PMC9845229 DOI: 10.1038/s41467-023-35954-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 01/10/2023] [Indexed: 01/19/2023] Open
Abstract
To industrialize printed full-color displays based on quantum-dot light-emitting diodes, one must explore the degradation mechanism and improve the operational stability of blue electroluminescence. Here, we report that although state-of-the-art blue quantum dots, with monotonically-graded core/shell/shell structures, feature near-unity photoluminescence quantum efficiency and efficient charge injection, the significant surface-bulk coupling at the quantum-dot level, revealed by the abnormal dipolar excited state, magnifies the impact of surface localized charges and limits operational lifetimes. Inspired by this, we propose blue quantum dots with a large core and an intermediate shell featuring nonmonotonically-graded energy levels. This strategy significantly reduces surface-bulk coupling and tunes emission wavelength without compromising charge injection. Using these quantum dots, we fabricate bottom-emitting devices with emission colors varying from near-Rec.2020-standard blue to sky blue. At an initial luminance of 1000 cd m-2, these devices exhibit T95 operational lifetimes ranging from 75 to 227 h, significantly surpassing the existing records.
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Affiliation(s)
- Xingtong Chen
- grid.263761.70000 0001 0198 0694Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123 Jiangsu China ,grid.263761.70000 0001 0198 0694Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123 Jiangsu China
| | - Xiongfeng Lin
- TCL Corporate Research, Shenzhen, 518067 Guangdong China
| | - Likuan Zhou
- TCL Corporate Research, Shenzhen, 518067 Guangdong China
| | - Xiaojuan Sun
- grid.263761.70000 0001 0198 0694Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123 Jiangsu China ,grid.263761.70000 0001 0198 0694Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123 Jiangsu China
| | - Rui Li
- grid.263761.70000 0001 0198 0694Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123 Jiangsu China ,grid.263761.70000 0001 0198 0694Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123 Jiangsu China
| | - Mengyu Chen
- grid.263761.70000 0001 0198 0694Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123 Jiangsu China ,grid.263761.70000 0001 0198 0694Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123 Jiangsu China
| | - Yixing Yang
- TCL Corporate Research, Shenzhen, 518067 Guangdong China
| | - Wenjun Hou
- TCL Corporate Research, Shenzhen, 518067 Guangdong China
| | - Longjia Wu
- TCL Corporate Research, Shenzhen, 518067 Guangdong China
| | - Weiran Cao
- TCL Corporate Research, Shenzhen, 518067 Guangdong China
| | - Xin Zhang
- TCL Corporate Research, Shenzhen, 518067 Guangdong China
| | - Xiaolin Yan
- TCL Corporate Research, Shenzhen, 518067 Guangdong China
| | - Song Chen
- grid.263761.70000 0001 0198 0694Suzhou Key Laboratory of Novel Semiconductor-optoelectronics Materials and Devices, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123 Jiangsu China ,grid.263761.70000 0001 0198 0694Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123 Jiangsu China
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29
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Zang S, Zhang X, Sun Y, Li N, Wang L, Li LS. Ligand-assisted structure tailoring of highly luminescent Cu-In-Zn-S/ZnS//ZnS quantum dots for bright and stable light-emitting diodes. Front Chem 2022; 10:1102514. [PMID: 36583153 PMCID: PMC9792774 DOI: 10.3389/fchem.2022.1102514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022] Open
Abstract
Harnessing environment-friendly and low-cost multinary Cu-In-Zn-S quantum dots (QDs) as emitters for light-emitting diodes (LEDs) has attracted great attention for display and lighting application. However, suboptimal QD structure is a huge obstacle, which results in serious non-radiative recombination and efficiency roll-off. Herein, we synthesized structure-tailored Cu-In-Zn-S/ZnS//ZnS QDs by improving the reactivity of shell growth by 2-ethylhexanoic acid (EHA) ligands. The EHA-assisted shell growth can boost an extended alloyed layer at the core-shell interface and a smoothed confinement barrier, which effectively passivate the interface defects and suppress Förster resonance energy transfer (FRET) process. These synthesized QDs display a bright photoluminescence emission (quantum yield of 83%) and a larger size of 8.4 nm. Moreover, the resulting LEDs based on the EHA-assisted QDs exhibit a maximum luminance of 8074 cd/m2, and a current efficiency of 7.3 cd/A with a low efficiency roll-off. Our results highlight a remarkable ligand strategy to tailor the QD structure for high performance QD-based LEDs.
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Affiliation(s)
- Shuaipu Zang
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, China,College of Science, Zhongyuan University of Technology, Zhengzhou, China
| | - Xuhui Zhang
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, China
| | - Yingying Sun
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, China
| | - Ning Li
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, China
| | - Lei Wang
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, China,*Correspondence: Lei Wang, ; Lin Song Li,
| | - Lin Song Li
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, China,*Correspondence: Lei Wang, ; Lin Song Li,
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30
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Chung DS, Davidson-Hall T, Cotella G, Lyu Q, Chun P, Aziz H. Significant Lifetime Enhancement in QLEDs by Reducing Interfacial Charge Accumulation via Fluorine Incorporation in the ZnO Electron Transport Layer. NANO-MICRO LETTERS 2022; 14:212. [PMID: 36333462 PMCID: PMC9636368 DOI: 10.1007/s40820-022-00970-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 10/08/2022] [Indexed: 05/22/2023]
Abstract
ZnO nanoparticles are widely used for the electron transport layers (ETLs) of quantum dots light emitting devices (QLEDs). In this work we show that incorporating fluorine (F) into the ZnO ETL results in significant enhancement in device electroluminescence stability, leading to LT50 at 100 cd m-2 of 2,370,000 h in red QLED, 47X longer than the control devices. X-ray photo-electron spectroscopy, time-of-flight secondary ion mass spectroscopy, photoluminescence and electrical measurements show that the F passivates oxygen vacancies and reduces electron traps in ZnO. Transient photoluminescence versus bias measurements and capacitance-voltage-luminance measurements reveal that the CF4 plasma-treated ETLs lead to increased electron concentration in the QD and the QD/hole transport layer interface, subsequently decreasing hole accumulation, and hence the higher stability. The findings provide new insights into the critical roles that optimizing charge distribution across the layers play in influencing stability and present a novel and simple approach for extending QLED lifetimes.
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Affiliation(s)
- Dong Seob Chung
- Department of Electrical and Computer Engineering, Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada.
| | - Tyler Davidson-Hall
- Department of Electrical and Computer Engineering, Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
| | - Giovanni Cotella
- Ipswich Research Centre, Huawei Technologies Research & Development (UK) Ltd., Phoenix House (B55), Adastral Park, Ipswich, IP5 3RE, UK
| | - Quan Lyu
- Ipswich Research Centre, Huawei Technologies Research & Development (UK) Ltd., Phoenix House (B55), Adastral Park, Ipswich, IP5 3RE, UK
| | - Peter Chun
- Ottawa IC Laboratory, Huawei Canada, 19 Allstate Parkway, Markham, ON, L3R 5B4, Canada
| | - Hany Aziz
- Department of Electrical and Computer Engineering, Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada.
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31
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Hu A, Bai P, Zhu Y, Tang Z, Xiao L, Gao Y. Controlled Core/Crown Growth Enables Blue-Emitting Colloidal Nanoplatelets with Efficient and Pure Photoluminescence. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2204120. [PMID: 36135780 DOI: 10.1002/smll.202204120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 08/18/2022] [Indexed: 06/16/2023]
Abstract
Colloidal semiconductor CdSe nanoplatelets (NPLs) feature ultranarrow and anisotropic emissions. However, the optical performance of blue-emitting NPLs is deteriorated by trap states, currently exhibiting tainted emissions and inferior photoluminescence quantum yields (PLQYs). Here, near trap-free blue-emitting NPLs are achieved by the controlled growth of the core/crown. Deep trap states in NPLs can be partially suppressed with the asymmetrical crown growth and are further suppressed with the growth of the small core and the alloyed symmetrical crown, yielding NPLs with pure blue emissions and near-unity PLQYs. Exciton dynamic research based on these NPLs indicates that the trap emission stems from surface traps. Besides, light-emitting diodes exhibiting ultranarrow emission centered around 461 nm with full-width-at-half-maximums down to 11 nm are fabricated using these NPLs.
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Affiliation(s)
- An Hu
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, P. R. China
| | - Peng Bai
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, P. R. China
| | - Yunke Zhu
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, P. R. China
| | - Zhenyu Tang
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, P. R. China
| | - Lixin Xiao
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, P. R. China
| | - Yunan Gao
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, P. R. China
- Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing, 100871, P. R. China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, P. R. China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu, 226010, P. R. China
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32
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Wang LX, Tang CG, Tan ZS, Phua HY, Chen J, Lei W, Png RQ, Chua LL, Ho PKH. Double-type-I charge-injection heterostructure for quantum-dot light-emitting diodes. MATERIALS HORIZONS 2022; 9:2147-2159. [PMID: 35616351 DOI: 10.1039/d1mh00859e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Enforcing balanced electron-hole injection into the emitter layer of quantum-dot light-emitting diodes (QLEDs) remains key to maximizing the quantum efficiency over a wide current density range. This was previously thought not possible for quantum dot (QD) emitters because of their very deep energy bands. Here, we show using Mesolight® blue-emitting CdZnSeS/ZnS QDs as a model that its valence levels are in fact considerably shallower than the corresponding band maximum of the bulk semiconductor, which makes the ideal double-type-I injection/confinement heterostructure accessible using a variety of polymer organic semiconductors as transport and injection layers. We demonstrate flat external quantum efficiency characteristics that indicate near perfect recombination within the QD layer over several decades of current density from the onset of device turn-on of about 10 μA cm-2, for both normal and inverted QLED architectures. We also demonstrate that these organic semiconductors do not chemically degrade the QDs, unlike the usual ZnMgO nanoparticles. However, these more efficient injection heterostructures expose a new vulnerability of the QDs to in device electrochemical degradation. The work here opens a clear path towards next-generation ultra-high-performance, all-solution-processed QLEDs.
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Affiliation(s)
- Li-Xi Wang
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, S117550, Singapore.
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing, People's Republic of China
| | - Cindy G Tang
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, S117550, Singapore.
| | - Zhao-Siu Tan
- Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, S117552, Singapore.
| | - Hao-Yu Phua
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, S117550, Singapore.
| | - Jing Chen
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing, People's Republic of China
| | - Wei Lei
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing, People's Republic of China
| | - Rui-Qi Png
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, S117550, Singapore.
| | - Lay-Lay Chua
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, S117550, Singapore.
- Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, S117552, Singapore.
| | - Peter K H Ho
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, S117550, Singapore.
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Zhang X, Li D, Zhang Z, Liu H, Wang S. Constructing Effective Hole Transport Channels in Cross-Linked Hole Transport Layer by Stacking Discotic Molecules for High Performance Deep Blue QLEDs. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200450. [PMID: 35652500 PMCID: PMC9376750 DOI: 10.1002/advs.202200450] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/28/2022] [Indexed: 06/15/2023]
Abstract
The inadequate hole injection limits the efficiency and lifetime of the blue quantum dot light-emitting diodes (QLEDs), which severely hampers their commercial applications. Here a new discotic molecule of 3,6,10,11-tetrakis(pentyloxy)triphenylene-2,7-diyl bis(2,2-dimethylpropanoate) (T5DP-2,7) is introduced, in which the hole transport channels with superior hole mobility (2.6 × 10-2 cm2 V-1 s-1 ) is formed by stacking. The composite hole transport material (HTM) is prepared by blending T5DP-2,7 with the cross-linked 4,4'- bis(3-vinyl-9H-carbazol-9-yl)-1,1'biphenyl (CBP-V) which shows the deep highest occupied molecular orbital energy level. The increased hole mobility of the target composite HTM from 10-4 to 10-3 cm2 V-1 s-1 as well as the stepwise energy levels facilitates the hole transport, which would be beneficial for more balanced carrier injection. This composite hole transport layer (HTL) has improved the deep-blue-emission performances of Commission International de I'Eclairage of (0.14, 0.04), luminance of 44080 cd m-2 , and external quantum efficiency of 18.59%. Furthermore, when L0 is 100 cd m-2 , the device lifetime T50 is extended from 139 to 502 h. The state-of-the-art performance shows the successful promotion of the high-efficiency for deep blue QLEDs, and indicates that the optimizing HTL by discotic molecule stacking can serve as an excellent alternative for the development of HTL in the future.
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Affiliation(s)
- Xinyu Zhang
- School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072P. R. China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)Tianjin300072P. R. China
| | - Dewang Li
- Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityBinhai New CityFuzhou350207P. R. China
- School of Materials Science and EngineeringTianjin Key Laboratory of Composite and Functional MaterialsTianjin UniversityTianjin300350P. R. China
| | - Zhenhu Zhang
- School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072P. R. China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)Tianjin300072P. R. China
| | - Hongli Liu
- School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072P. R. China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)Tianjin300072P. R. China
| | - Shirong Wang
- School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072P. R. China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)Tianjin300072P. R. China
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Abstract
For a light-emitting diode (LED) to generate light, the minimum voltage required is widely considered to be the emitter’s bandgap divided by the elementary charge. Here we show for many classes of LEDs, including those based on perovskite, organic, quantum-dot and III–V semiconductors, light emission can be observed at record-low voltages of 36–60% of their bandgaps, exhibiting a large apparent energy gain of 0.6–1.4 eV per photon. For 17 types of LEDs with different modes of charge injection and recombination (dark saturation currents of ~10−39–10−15 mA cm−2), their emission intensity-voltage curves under low voltages show similar behaviours. These observations and their consistency with the diode simulations suggest the ultralow-voltage electroluminescence arises from a universal origin—the radiative recombination of non-thermal-equilibrium band-edge carriers whose populations are determined by the Fermi-Dirac function perturbed by a small external bias. These results indicate the potential of low-voltage LEDs for communications, computational and energy applications. Light emission from 17 types of LEDs is observed at record-low voltages of 36–60% of the bandgaps, which cannot be explained by earlier theories. The electroluminescence-voltage curves reveal a unified mechanism for ultralow-voltage LED operation.
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35
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Kim J, Hahm D, Bae WK, Lee H, Kwak J. Transient Dynamics of Charges and Excitons in Quantum Dot Light-Emitting Diodes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2202290. [PMID: 35754301 DOI: 10.1002/smll.202202290] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 05/28/2022] [Indexed: 06/15/2023]
Abstract
Wide interest in quantum dot (QD) light-emitting diodes (QLEDs) for potential application to display devices and light sources has led to their rapid advancement in device performance. Despite such progress, detailed operation mechanisms of QLEDs, which are necessary for the fundamental understanding and further improvements, have been still uncertain because of the intricate interaction between charges and excitons in electrical operation. In this work, the transient electroluminescence (TREL) signals of dichromatic QLEDs which are purposely designed to consist of two different color-emitting QD layers are analyzed. As a result, not only can the charge injection and exciton recombination processes be visualized but the electron mobility of the QD layer can also be estimated. Furthermore, the effects of Förster resonant energy transfer between two QDs and exciton quenching near the QD layer are quantitatively measured in QLED operation. The authors believe that their results based on TREL analyses will contribute to the understanding and development of high-performance QLEDs.
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Affiliation(s)
- Jaeyoul Kim
- Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University, Seoul, 08826, Republic of Korea
| | - Donghyo Hahm
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Wan Ki Bae
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Hyunho Lee
- Department of Electronic Engineering, Kwangwoon University, Seoul, 01897, Republic of Korea
| | - Jeonghun Kwak
- Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University, Seoul, 08826, Republic of Korea
- Soft Foundry Institute, Seoul National University, 1-Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea
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36
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Zhang W, Ren F, Wen Y, Xu Z, Sun J, Yan Z, Ding L, Hai X, Zhang Q. Enhancing Hole Transport of Quantum-Dot Light-Emitting Diodes by a Cruciform Oligothiophene for Effective p-Type Doping. Macromol Rapid Commun 2022; 43:e2200187. [PMID: 35451198 DOI: 10.1002/marc.202200187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 04/06/2022] [Indexed: 11/07/2022]
Abstract
Effective p-type doping is essential to enhance hole transport and balance electron-hole injection in quantum dot light-emitting diodes (QLEDs). Here, an oligothiophene material is adopted as a p-type dopant in the hole-transport layer, considering its cruciform cross-centre structure, precise molecular weight, and high purity. Compared with the dopant-free counterpart, hole transport capability at the optimal doping level exhibits a significant improvement, producing a boosted external quantum efficiency (EQE) and luminance up to 20.8%, 213,439 cd m-2 , respectively, among the highest reported on the red-light emission. The work indicates the potential applications of oligothiophene material in red light-emitting devices. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Wenjing Zhang
- Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang, Jiangxi, 330063, P. R. China.,Key Laboratory for Special Functional Materials of Ministry of Education, School of Materials, Henan University, Kaifeng, Henan, 475004, P. R. China
| | - Fumeng Ren
- Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang, Jiangxi, 330063, P. R. China.,Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, P. R. China
| | - Yu Wen
- Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang, Jiangxi, 330063, P. R. China
| | - Zhangwang Xu
- Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang, Jiangxi, 330063, P. R. China
| | - Juan Sun
- Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang, Jiangxi, 330063, P. R. China
| | - Zhenzhen Yan
- Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang, Jiangxi, 330063, P. R. China
| | - Lei Ding
- Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang, Jiangxi, 330063, P. R. China
| | - Xia Hai
- Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang, Jiangxi, 330063, P. R. China
| | - Qin Zhang
- Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang, Jiangxi, 330063, P. R. China
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37
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Yu P, Yuan Q, Zhao J, Zhang H, Ji W. Electronic and Excitonic Processes in Quantum Dot Light-Emitting Diodes. J Phys Chem Lett 2022; 13:2878-2884. [PMID: 35333050 DOI: 10.1021/acs.jpclett.2c00604] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A modified Langevin model has been proposed to study the electronic and excitonic dynamic processes in quantum dot light-emitting diodes (QLEDs), and the electroluminescence onset processes of the QLEDs under different charge-injection conditions have been explored. The simulation results are in good agreement with experimental curves, confirming the feasibility of this model. It is demonstrated that the formation of an exciton on the quantum dots (QDs) with one electron injected first followed by one hole is much more effective than that with the reverse sequence. That is, charging a QD with one electron first is more favorable for device performance enhancement, which is attributed to the low (high) Auger recombination rate of negative (positive) trions of commonly used type I QDs. Additionally, we demonstrate that enough electron injection is one of the prerequisites for high-performance QLEDs based on these type I QDs.
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Affiliation(s)
- Panlong Yu
- Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), Department of Physics, Jilin University, Changchun, Jilin 130023, People's Republic of China
| | - Qilin Yuan
- Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), Department of Physics, Jilin University, Changchun, Jilin 130023, People's Republic of China
| | - Jialong Zhao
- Center on Nanoenergy Research, School of Physical Science and Technology, Guangxi University, Nanning, Guangxi 530004, People's Republic of China
| | - Hanzhuang Zhang
- Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), Department of Physics, Jilin University, Changchun, Jilin 130023, People's Republic of China
| | - Wenyu Ji
- Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), Department of Physics, Jilin University, Changchun, Jilin 130023, People's Republic of China
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38
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Zhang W, Du J, Wei Q, Zhang D, Pei S, Tong B, Liu Z, Liang Y, Cheng HM, Ren W. Fabrication of Large-Area Uniform Nanometer-Thick Functional Layers and Their Stacks for Flexible Quantum Dot Light-Emitting Diodes. SMALL METHODS 2022; 6:e2101030. [PMID: 35174984 DOI: 10.1002/smtd.202101030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 11/14/2021] [Indexed: 06/14/2023]
Abstract
Large-area fabrication and stacking of various nanometer-thick functional layers from solutions is essentially important for the construction of flexible thin-film optoelectronic devices, but very challenging. The existing fabrication methods suffer from either non-uniformity caused by the coffee-ring effect or serious solution waste (excess of 90% for spin coating), and are hard to scale up and create stacks. Here, it is shown that centrifugal casting is a universal, scalable, and efficient method to fabricate uniform nanometer-thick films and their stacks of various materials. The coffee-ring effect is effectively suppressed, the solution utilization ratio is higher than ≈61%, and the films/stacks show a smooth surface/high-quality interface. Using this method, flexible quantum dot light-emitting diode displays with uniform luminance in a large lighting area of ≈115 cm2 that have not been achieved even on rigid substrates by the existing methods, are realized. This efficient and low-cost solution processing method paves a way for large-area fabrication of various flexible thin-film optoelectronic devices.
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Affiliation(s)
- Weimin Zhang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
- School of Materials Science and Engineering, University of Science and Technology of China, Shenyang, 110016, P. R. China
| | - Jinhong Du
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
- School of Materials Science and Engineering, University of Science and Technology of China, Shenyang, 110016, P. R. China
| | - Qinwei Wei
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
- School of Materials Science and Engineering, University of Science and Technology of China, Shenyang, 110016, P. R. China
| | - Dingdong Zhang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
| | - Songfeng Pei
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
| | - Bo Tong
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
- School of Materials Science and Engineering, University of Science and Technology of China, Shenyang, 110016, P. R. China
| | - Zhibo Liu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
| | - Yan Liang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
| | - Hui-Ming Cheng
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
- School of Materials Science and Engineering, University of Science and Technology of China, Shenyang, 110016, P. R. China
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Wencai Ren
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
- School of Materials Science and Engineering, University of Science and Technology of China, Shenyang, 110016, P. R. China
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39
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Su Q, Chen S. Thermal assisted up-conversion electroluminescence in quantum dot light emitting diodes. Nat Commun 2022; 13:369. [PMID: 35042857 PMCID: PMC8766545 DOI: 10.1038/s41467-022-28037-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 01/06/2022] [Indexed: 11/09/2022] Open
Abstract
Up-conversion electroluminescence, in which the energy of a emitted photon is higher than that of the excitation electron, is observed in quantum-dot light-emitting diodes. Here, we study its mechanism by investigating the effect of thermal energy on the charge injection dynamic. Based on the results of temperature-dependent electroluminescence and theoretical analysis, we reveal that at sub-bandgap voltage, holes can be successfully injected into quantum-dots via thermal-assisted thermionic-emission mechanism, thereby enabling the sub-bandgap turn-on and up-conversion electroluminescence of the devices. Further theoretical deduction and experimental results confirm that thermal-assisted hole-injection is the universal mechanism responsible for the up-conversion electroluminescence. This work uncovers the charge injection process and unlocks the sub-bandgap turn-on mechanism, which paves the road for the development of up-conversion devices with power conversion efficiency over 100%. How holes are injected into quantum dots at sub-bandgap bias has puzzled researchers for years. Here, authors show, using temperature-dependent electroluminescence (EL) and theoretical analysis, such injection occurs via thermal-assisted thermionic-emission, consequently enabling the sub-bandgap turn-on and up-conversion EL.
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Affiliation(s)
- Qiang Su
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, People's Republic of China
| | - Shuming Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, People's Republic of China. .,Key Laboratory of Energy Conversion and Storage Technologies (Southern University of Science and Technology), Ministry of Education, Shenzhen, 518055, People's Republic of China.
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40
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Chen L, Qin Z, Chen S. Ultrahigh Resolution Pixelated Top-Emitting Quantum-Dot Light-Emitting Diodes Enabled by Color-Converting Cavities. SMALL METHODS 2022; 6:e2101090. [PMID: 35041269 DOI: 10.1002/smtd.202101090] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/09/2021] [Indexed: 06/14/2023]
Abstract
Realizing pixelated quantum-dot light-emitting diodes for high-resolution displays remains a challenging task because of the difficulty of fine patterning the quantum-dots. In this study, instead of patterning the quantum-dots, the color-converting cavities for realizing high-resolution pixelated emission are developed. By defining the thicknesses of the transparent electrodes (phase tuning layers) through a photolithographic process, the resultant cavities can selectively convert the unpatterned quantum-dot white emission as saturated red, green, and blue emission with a brightness of 22170, 51930, and 3064 cd m-2 at 5.5 V, respectively. The developed method enables the realization of ultrahigh density red, green, and blue emission for a display with a resolution of ≈1700 pixel-per-inch and a color gamut of 111% National Television System Committee; together with the advantages of quantum-dot patterning-free, color-filter-free and high brightness, the demonstrated architecture could find potential applications in various displays ranging from cell phone to emerging virtual reality and augmented reality displays.
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Affiliation(s)
- Lianna Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Zhiyuan Qin
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Shuming Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
- Key Laboratory of Energy Conversion and Storage Technologies (Southern University of Science and Technology), Ministry of Education, Shenzhen, 518055, P. R. China
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41
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Zhang H, Chen L, Chen S. Quantum-dot and organic hybrid tandem light-emitting diodes with color-selecting intermediate electrodes for full-color displays. NANOSCALE 2021; 13:16781-16789. [PMID: 34604890 DOI: 10.1039/d1nr04630f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The immaturity of the color patterning technology and the poor stability of blue (B) quantum-dots are two of the challenges that restrict the development of quantum-dot electroluminescence displays. In this work, we demonstrate a hybrid tandem light-emitting diode (LED), in which a yellow (Y) quantum-dot LED and a B organic LED are vertically connected using an IZO/Ag intermediate electrode. The transparent IZO sets the resonance wavelength of the Y-QLED and thus selectively converts the yellow emission into R or G emission, while the semi-reflective Ag enhances the optical interference of the B LED and hence improves the color saturation of the B emission. Enabled by the multi-functionalities of color-selection and color-enhancement of the intermediate electrode, the tandem LED can emit independently controllable R, G and B colors with a high color gamut of ∼110% NTSC without the need to pattern the light-emitting layers. The demonstrated tandem LED could provide a promising way for the realization of emitting-layer-patterning-free, color-filter-free and wide-color-gamut electroluminescence displays.
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Affiliation(s)
- Heng Zhang
- Harbin Institute of Technology, Harbin, 150001, P. R. China
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China.
| | - Lianna Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China.
| | - Shuming Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China.
- Key Laboratory of Energy Conversion and Storage Technologies (Southern University of Science and Technology), Ministry of Education, Shenzhen, 518055, P. R. China
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Shen Q, Hao Y, Ma L, Wang X. Comparative Study of Red/Green/Blue Quantum-Dot Light-Emitting Diodes by Time-Resolved Transient Electroluminescence. J Phys Chem Lett 2021; 12:7019-7025. [PMID: 34286994 DOI: 10.1021/acs.jpclett.1c01560] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
To understand the electronic processes in quantum-dot light-emitting diodes (QLEDs), a comparative study was performed by time-resolved transient electroluminescence (TREL). We fabricated red, green, and blue (R-, G-, and B-) QLEDs with poly(9,9-dioctylfluorene-co-N-(4-sec-butylphenyl)diphenylamine) as the hole-transporting layer with conventional structures. The external quantum efficiency (EQE) and current efficiency were 19.2% and 22.7 cd A-1 for R-QLEDs, 21.1% and 93.3 cd A-1 for G-QLEDs, and 10.6% and 10.4 cd A-1 for B-QLEDs, respectively. The TREL results for B-QLEDs were remarkably different from those for R- and G-QLEDs because of the insufficient electron injection crossing the type II heterojunction between the emission layer and the electron-transporting layer. We further applied poly(N-vinylcarbazole) as the hole-transporting layer and obtained much better performance for B-QLEDs, with EQE and current efficiency of 15.9% and 15.4 cd A-1, respectively. Concomitant with the increase in EQE are an increase in the turn-on voltage from 2.3 to 3.7 V and a transient electroluminescence spike after voltage turn-off.
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Affiliation(s)
- Qibin Shen
- Department of Physics and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China
| | - Yanlei Hao
- Center for Chemistry of High-Performance and Novel Materials, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Luying Ma
- Center for Chemistry of High-Performance and Novel Materials, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Xiaoyu Wang
- Department of Physics and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China
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43
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Cheng Y, Wan H, Liang T, Liu C, Wu M, Hong H, Liu K, Shen H. Continuously Graded Quantum Dots: Synthesis, Applications in Quantum Dot Light-Emitting Diodes, and Perspectives. J Phys Chem Lett 2021; 12:5967-5978. [PMID: 34160222 DOI: 10.1021/acs.jpclett.1c01554] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Colloidal quantum dot (QD) light-emitting diodes (QLEDs) hold the promise of next-generation displays and illumination owing to their excellent color saturation, high efficiency, and solution processability. For achieving high-performance light-emitting diodes (LEDs), engineering the fine compositions and structures of QDs is of paramount importance and attracts tremendous research interest. The recently developed continuously graded QDs (cg-QDs) with gradually altered nanocompositions and electronic band structures present the most advanced example in this area. In this Perspective, we summarize the current progress in LEDs based on cg-QDs, mainly concentrating on their synthesis and advantages in addressing the great challenges in QLEDs, like efficiency roll-off at high current densities, short operation lifetimes at high brightness, and low brightness near the voltage around the bandgap. In addition, we propose accessible approaches exploiting the cutting-edge mechanisms and techniques to further optimize and improve the performance of QLEDs.
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Affiliation(s)
- Yang Cheng
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Key Laboratory for Special Functional Materials, Ministry of Education, School of Materials Science and Engineering, Henan University, Kaifeng 475004, China
| | - Haoyue Wan
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Tianyu Liang
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Can Liu
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Muhong Wu
- International Center for Quantum Materials, Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China
- Songshan Lake Laboratory for Materials Science, Dongguan 523808, China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing 100871, China
| | - Hao Hong
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Kaihui Liu
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- International Center for Quantum Materials, Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China
| | - Huaibin Shen
- Key Laboratory for Special Functional Materials, Ministry of Education, School of Materials Science and Engineering, Henan University, Kaifeng 475004, China
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Effects of UV Irradiation and Storage on the Performance of Inverted Red Quantum-Dot Light-Emitting Diodes. NANOMATERIALS 2021; 11:nano11061606. [PMID: 34207371 PMCID: PMC8235399 DOI: 10.3390/nano11061606] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/10/2021] [Accepted: 06/16/2021] [Indexed: 01/24/2023]
Abstract
We report the effects of ultraviolet (UV) irradiation and storage on the performance of ZnO-based inverted quantum-dot light-emitting diodes (QLEDs). The effects of UV irradiation on the electrical properties of ZnO nanoparticles (NPs) were investigated. We demonstrate that the charge balance was enhanced by improving the electron injection. The maximum external quantum efficiency (EQE) and power efficiency (PE) of QLEDs were increased by 26% and 143% after UV irradiation for 15 min. In addition, we investigated the storage stabilities of the inverted QLEDs. During the storage period, the electron current from ZnO gradually decreased, causing a reduction in the device current. However, the QLEDs demonstrated improvements in maximum EQE by 20.7% after two days of storage. Our analysis indicates that the suppression of exciton quenching at the interface of ZnO and quantum dots (QDs) during the storage period could result in the enhancement of EQE. This study provides a comprehension of the generally neglected factors, which could be conducive to the realization of high-efficiency and highly storage-stable practical applications.
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45
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Zheng W, Song D, Zhao S, Qiao B, Xu Z, Chen J, Liu G, Shen C. Performance improvements in all-solution processed inverted QLEDs realized by inserting an electron blocking layer. NANOTECHNOLOGY 2021; 32:335204. [PMID: 33957607 DOI: 10.1088/1361-6528/abfe8e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 05/06/2021] [Indexed: 06/12/2023]
Abstract
Highly efficient, all-solution processed inverted quantum dot light-emitting diodes (QLEDs) are demonstrated by employing 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (TmPyPB) layer as electron blocking layer. Electron injection from ZnO electron transport layer to quantum dots (QDs) emission layer (EML) can be adjusted by thickness of TmPyPB layer, enabling the balanced charge carriers in QDs EML. With optimal thickness of this TmPyPB adjuster, 59.7% increment in the device current efficiency (from 8.2 to 13.1 cd A-1) and 46.2% improvement in the maximum luminance (from 31916 to 46674 cd m-2) are achieved, compared with those of the control QLED which has double hole transport layer structure. On the other hand, we find luminescence quenching process, which often happens at the interface of ZnO nanoparticles and QDs, is not obvious in our QLEDs, in which the ZnO layer is fabricated in precursor method, and this conclusion is verified through Time Resolution Photoluminescence test. In a word, this strategy provides a direction for optimizing charge carrier balance in all-solution processed inverted QLED.
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Affiliation(s)
- Weiye Zheng
- Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044, People's Republic of China
- Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, People's Republic of China
| | - Dandan Song
- Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044, People's Republic of China
- Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, People's Republic of China
| | - Suling Zhao
- Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044, People's Republic of China
- Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, People's Republic of China
| | - Bo Qiao
- Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044, People's Republic of China
- Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, People's Republic of China
| | - Zheng Xu
- Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044, People's Republic of China
- Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, People's Republic of China
| | - Junfei Chen
- Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044, People's Republic of China
- Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, People's Republic of China
| | - Guoxu Liu
- ShineOn (Beijing) Technology Co., Ltd, People's Republic of China
| | - Chongyu Shen
- ShineOn (Beijing) Technology Co., Ltd, People's Republic of China
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46
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Xu J, Wang L, Zhao X, Shi Y, Shi Y, Liu T. High-Performance Blue Quantum Dot Light Emitting Diode via Solvent Optimization Strategy for ZnO Nanoparticles. NANOMATERIALS 2021; 11:nano11040959. [PMID: 33918667 PMCID: PMC8070000 DOI: 10.3390/nano11040959] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/03/2021] [Accepted: 04/07/2021] [Indexed: 11/16/2022]
Abstract
Here, we report on the high-performance blue quantum dots (QDs) light-emitting diodes (QLEDs), in which the ZnO nanoparticles (NPs) are employed as the electron transport layer (ETL) and optimized with different alcohol solvents. The experimental results demonstrate that the properties of solvent used for ZnO NPs—such as polarity, viscosity and boiling point—play a crucial role in the quality of film where they modulate the electron injection across the QDs/ETL interface. The maximum current efficiency of 3.02 cd/A and external quantum efficiency (EQE) of 3.3% are achieved for blue QLEDs with ZnO NPs dispersed in butanol, exhibiting obvious enhancement compared with the other solvents. This work provides a new method to select proper solvent for ETL which can further improve the device performance.
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Affiliation(s)
- Ji Xu
- School of Electronic and Information Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China;
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China; (Y.S.); (Y.S.)
- Correspondence: (J.X.); (L.W.); (T.L.)
| | - Lixi Wang
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China; (Y.S.); (Y.S.)
- Correspondence: (J.X.); (L.W.); (T.L.)
| | - Xueliang Zhao
- School of Electronic and Information Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China;
| | - Yutong Shi
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China; (Y.S.); (Y.S.)
| | - Yongjiao Shi
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China; (Y.S.); (Y.S.)
| | - Ting Liu
- Department of Physics, College of Science, Beijing University of Chemical Technology, 15 East Road, Beijing 100029, China
- Correspondence: (J.X.); (L.W.); (T.L.)
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47
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Kim T, Won YH, Jang E, Kim D. Negative Trion Auger Recombination in Highly Luminescent InP/ZnSe/ZnS Quantum Dots. NANO LETTERS 2021; 21:2111-2116. [PMID: 33635669 DOI: 10.1021/acs.nanolett.0c04740] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Upon demonstrating self-luminescing quantum dot based light-emitting devices (QD-LEDs), rapid Auger recombination acts as one of the performance limiting factors. Here, we report the Auger processes of highly luminescent InP/ZnSe/ZnS QDs with different midshell structures that affect the performances of QD-LEDs. Transient PL measurements reveal that exciton-exciton binding energy is dependent on the midshell thickness, which implies that the intercarrier Coulomb interaction caused by the introduction of excess charges may come under the influence of midshell thickness which is in contrast with the nearly stationary single exciton behavior. Photochemical electron-doping and optical measurements of a single QD show that negative trion Auger recombination exhibits strong correlation with midshell thickness, which is supported by the dynamics of a hot electron generated in the midshell. These results highlight the role of excess electrons and the effects of engineered shell structures in InP/ZnSe/ZnS QDs, which eventually determine the Auger recombination and QD-LED performances.
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Affiliation(s)
- Taehee Kim
- Department of Chemistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Yu-Ho Won
- Samsung Advanced Institute of Technology, Samsung Electronics, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Eunjoo Jang
- Samsung Advanced Institute of Technology, Samsung Electronics, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Dongho Kim
- Department of Chemistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
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48
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Yang J, Choi MK, Yang UJ, Kim SY, Kim YS, Kim JH, Kim DH, Hyeon T. Toward Full-Color Electroluminescent Quantum Dot Displays. NANO LETTERS 2021; 21:26-33. [PMID: 33258610 DOI: 10.1021/acs.nanolett.0c03939] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Colloidal quantum dots (QDs) exhibit unique characteristics such as facile color tunability, pure color emission with extremely narrow bandwidths, high luminescence efficiency, and high photostability. In addition, quantum dot light-emitting diodes (QLEDs) feature bright electroluminescence, low turn-on voltage, and ultrathin form factor, making them a promising candidate for next-generation displays. To achieve the overarching goal of the full-color display based on the electroluminescence of QDs, however it is essential to enhance the performance of QLEDs further for each color (e.g., red, green, and blue; RGB) and develop novel techniques for patterning RGB QD pixels without cross-contamination. Here, we present state-of-the-art material, process, and device technologies for full-color QLED-based displays. First, we highlight recent advances in the development of efficient red-, green-, and blue-monochromatic QLEDs. In particular, we focus on the progress of heavy-metal-free QLEDs. Then, we describe patterning techniques for individual RGB QDs to fabricate pixelated displays. Finally, we briefly summarize applications of such QLEDs, presenting the possibility of full-color QLED-based displays.
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Affiliation(s)
- Jiwoong Yang
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - Moon Kee Choi
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - U Jeong Yang
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Seo Young Kim
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - Young Seong Kim
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Jeong Hyun Kim
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Dae-Hyeong Kim
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Taeghwan Hyeon
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University (SNU), Seoul 08826, Republic of Korea
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49
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Zhang M, Deng H, Meng L, Wang H, Wang Y, Liu H. Direct Writing Large‐Area Multi‐Layer Ultrasmooth Films by an All‐Solution Process: Toward High‐Performance QLEDs. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202012013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Min Zhang
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education School of Chemistry Beijing Advanced Innovation Center for Biomedical Engineering International Research Institute for Multidisciplinary Science Beihang University No. 37, Xueyuan Road, Haidian District Beijing 100191 P. R. China
| | - Huanhuan Deng
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education School of Chemistry Beijing Advanced Innovation Center for Biomedical Engineering International Research Institute for Multidisciplinary Science Beihang University No. 37, Xueyuan Road, Haidian District Beijing 100191 P. R. China
| | - Lili Meng
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education School of Chemistry Beijing Advanced Innovation Center for Biomedical Engineering International Research Institute for Multidisciplinary Science Beihang University No. 37, Xueyuan Road, Haidian District Beijing 100191 P. R. China
| | - Hongqin Wang
- Suzhou Xingshuo Nanotech Co., Ltd (Mesolight) No. 99 Jinji Lake Road, Suzhou Industrial Park Suzhou 215123 P. R. China
| | - Yunjun Wang
- Suzhou Xingshuo Nanotech Co., Ltd (Mesolight) No. 99 Jinji Lake Road, Suzhou Industrial Park Suzhou 215123 P. R. China
| | - Huan Liu
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education School of Chemistry Beijing Advanced Innovation Center for Biomedical Engineering International Research Institute for Multidisciplinary Science Beihang University No. 37, Xueyuan Road, Haidian District Beijing 100191 P. R. China
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50
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Zhang M, Deng H, Meng L, Wang H, Wang Y, Liu H. Direct Writing Large-Area Multi-Layer Ultrasmooth Films by an All-Solution Process: Toward High-Performance QLEDs. Angew Chem Int Ed Engl 2021; 60:680-684. [PMID: 32964629 DOI: 10.1002/anie.202012013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Indexed: 12/19/2022]
Abstract
With increasing the film area/layer, deteriorating in both smoothness and uniformity of thin-films frequently happen, which remains a barrier for making large-area quantum dot light-emitting diodes (QLEDs) by solution processes. Here, we demonstrated a facile all-solution process guided by the conical fiber array to write multi-layer ultrasmooth thin-films directly in centimeter scale. The side-by-side fibrous array helps to align surface tensions at the tri-phase contact line to facilitate large-area homogeneous deposition, which was verified by theoretical simulation. The Laplace pressure along individual conical fiber contributes to the steady liquid transfer. Thin-films with small roughness (<2.03 nm) and large-area (2×2 cm2 ) uniformity were prepared sequentially on the target substrate, leading to large-area high-performance QLEDs. The result offers new insights for fabricating large-area high-performance thin-film devices.
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Affiliation(s)
- Min Zhang
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, International Research Institute for Multidisciplinary Science, Beihang University, No. 37, Xueyuan Road, Haidian District, Beijing, 100191, P. R. China
| | - Huanhuan Deng
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, International Research Institute for Multidisciplinary Science, Beihang University, No. 37, Xueyuan Road, Haidian District, Beijing, 100191, P. R. China
| | - Lili Meng
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, International Research Institute for Multidisciplinary Science, Beihang University, No. 37, Xueyuan Road, Haidian District, Beijing, 100191, P. R. China
| | - Hongqin Wang
- Suzhou Xingshuo Nanotech Co., Ltd (Mesolight), No. 99 Jinji Lake Road, Suzhou Industrial Park, Suzhou, 215123, P. R. China
| | - Yunjun Wang
- Suzhou Xingshuo Nanotech Co., Ltd (Mesolight), No. 99 Jinji Lake Road, Suzhou Industrial Park, Suzhou, 215123, P. R. China
| | - Huan Liu
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, International Research Institute for Multidisciplinary Science, Beihang University, No. 37, Xueyuan Road, Haidian District, Beijing, 100191, P. R. China
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