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Zhang T, Wang L, Jiang R, Wu Z, Han Y, Xu B, Jin X, Li Q, Bai J. Well-type thick-shell quantum dots combined with double hole transport layers device structure assisted realization of high-performance quantum dot light-emitting diodes. OPTICS EXPRESS 2024; 32:20618-20628. [PMID: 38859439 DOI: 10.1364/oe.523932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 05/12/2024] [Indexed: 06/12/2024]
Abstract
Quantum dot (QD) light-emitting diodes (QLEDs) are promising for next-generation lighting and displays. Considering the optimization design of both the QD and device structure is expected to improve the QLED's performance significantly but has rarely been reported. Here, we use the thick-shell QDs combined with a dual-hole transport layer device structure to construct a high-efficiency QLED. The optimized thick-shell QDs with CdS/CdSe/CdS/ZnS seed/spherical quantum well/shell/shell geometry exhibit a high photoluminescence quantum yield of 96% at a shell thickness of 5.9 nm. The intermediate emissive CdSe layer with coherent strain ensures defect-free growth of the thick CdS and ZnS outer shells. Based on the orthogonal solvents assisted Poly-TPD&PVK dual-hole transport layer device architecture, the champion QLED achieved a maximum external quantum efficiency of 22.5% and a maximum luminance of 259955 cd m-2, which are 1.6 and 3.7 times that of thin-shell QDs based devices with single hole transport layer, respectively. Our study provides a feasible idea for further improving the performance of QLED devices.
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Fan J, Han C, Yang G, Song B, Xu R, Xiang C, Zhang T, Qian L. Recent Progress of Quantum Dots Light-Emitting Diodes: Materials, Device Structures, and Display Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2312948. [PMID: 38813832 DOI: 10.1002/adma.202312948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 04/05/2024] [Indexed: 05/31/2024]
Abstract
Colloidal quantum dots (QDs), as a class of 0D semiconductor materials, have generated widespread interest due to their adjustable band gap, exceptional color purity, near-unity quantum yield, and solution-processability. With decades of dedicated research, the potential applications of quantum dots have garnered significant recognition in both the academic and industrial communities. Furthermore, the related quantum dot light-emitting diodes (QLEDs) stand out as one of the most promising contenders for the next-generation display technologies. Although QD-based color conversion films are applied to improve the color gamut of existing display technologies, the broader application of QLED devices remains in its nascent stages, facing many challenges on the path to commercialization. This review encapsulates the historical discovery and subsequent research advancements in QD materials and their synthesis methods. Additionally, the working mechanisms and architectural design of QLED prototype devices are discussed. Furthermore, the review surveys the latest advancements of QLED devices within the display industry. The narrative concludes with an examination of the challenges and perspectives of QLED technology in the foreseeable future.
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Affiliation(s)
- Junpeng Fan
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, P. R. China
- Laboratory of Advanced Nano-Optoelectronic Materials and Devices, Qianwan Institute of CNITECH, Ningbo, 315000, P. R. China
| | - Changfeng Han
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, P. R. China
- Laboratory of Advanced Nano-Optoelectronic Materials and Devices, Qianwan Institute of CNITECH, Ningbo, 315000, P. R. China
| | - Guojian Yang
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, P. R. China
- Laboratory of Advanced Nano-Optoelectronic Materials and Devices, Qianwan Institute of CNITECH, Ningbo, 315000, P. R. China
| | - Bin Song
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, P. R. China
- Department of Materials Science and Engineering, Xiamen University, Xiamen, 361005, P. R. China
| | - Rui Xu
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, P. R. China
- Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham Ningbo China, Ningbo, 315100, P. R. China
| | - Chaoyu Xiang
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, P. R. China
- Laboratory of Advanced Nano-Optoelectronic Materials and Devices, Qianwan Institute of CNITECH, Ningbo, 315000, P. R. China
| | - Ting Zhang
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, P. R. China
- Laboratory of Advanced Nano-Optoelectronic Materials and Devices, Qianwan Institute of CNITECH, Ningbo, 315000, P. R. China
| | - Lei Qian
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, P. R. China
- Laboratory of Advanced Nano-Optoelectronic Materials and Devices, Qianwan Institute of CNITECH, Ningbo, 315000, P. R. China
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Xu R, Lai S, Zhang Y, Zhang X. Research Progress of Heavy-Metal-Free Quantum Dot Light-Emitting Diodes. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:832. [PMID: 38786788 PMCID: PMC11124338 DOI: 10.3390/nano14100832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 04/29/2024] [Accepted: 05/07/2024] [Indexed: 05/25/2024]
Abstract
At present, heavy-metal-free quantum dot light-emitting diodes (QLEDs) have shown great potential as a research hotspot in the field of optoelectronic devices. This article reviews the research on heavy-metal-free quantum dot (QD) materials and light-emitting diode (LED) devices. In the first section, we discussed the hazards of heavy-metal-containing quantum dots (QDs), such as environmental pollution and human health risks. Next, the main representatives of heavy-metal-free QDs were introduced, such as InP, ZnE (E=S, Se and Te), CuInS2, Ag2S, and so on. In the next section, we discussed the synthesis methods of heavy-metal-free QDs, including the hot injection (HI) method, the heat up (HU) method, the cation exchange (CE) method, the successful ionic layer adsorption and reaction (SILAR) method, and so on. Finally, important progress in the development of heavy-metal-free QLEDs was summarized in three aspects (QD emitter layer, hole transport layer, and electron transport layer).
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Affiliation(s)
| | | | | | - Xiaoli Zhang
- Guangdong Provincial Key Laboratory of Information Photonics Technology, School of Physics and Opto-Electronic Engineering, Guangdong University of Technology, Guangzhou 510006, China; (R.X.); (S.L.); (Y.Z.)
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Olejnik-Fehér N, Jędrzejewska M, Wolska-Pietkiewicz M, Lee D, Paëpe GD, Lewiński J. On the Fate of Lithium Ions in Sol-Gel Derived Zinc Oxide Nanocrystals. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2309984. [PMID: 38497489 DOI: 10.1002/smll.202309984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 02/28/2024] [Indexed: 03/19/2024]
Abstract
Among diverse chemical synthetic approaches to zinc oxide nanocrystals (ZnO NCs), ubiquitous inorganic sol-gel methodology proved crucial for advancements in ZnO-based nanoscience. Strikingly, unlike the exquisite level of control over morphology and size dispersity achieved in ZnO NC syntheses, the purity of the crystalline phase, as well as the understanding of the surface structure and the character of the inorganic-organic interface, have been limited to vague descriptors until very recently. Herein, ZnO NCs applying the standard sol-gel synthetic protocol are synthesized with zinc acetate and lithium hydroxide and tracked the integration of lithium (Li) cations into the interior and exterior of nanoparticles by combining various techniques, including advanced solid-state NMR methods. In contrast to common views, it is demonstrated that Li+ ions remain kinetically trapped in the inorganic core, enter into a shallow subsurface layer, and generate "swelling" of the surface and interface regions. Thus, this work enabled both the determination of the NCs' structural imperfections and an in-depth understanding of the unappreciated role of the Li+ ions in impacting the doping and the passivation of sol-gel-derived ZnO nanomaterials.
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Affiliation(s)
- Natalia Olejnik-Fehér
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw, 01-224, Poland
- Université Grenoble Alpes, CEA, IRIG, MEM, Grenoble, 38000, France
| | - Maria Jędrzejewska
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw, 01-224, Poland
| | | | - Daniel Lee
- Université Grenoble Alpes, CEA, IRIG, MEM, Grenoble, 38000, France
| | - Gaël De Paëpe
- Université Grenoble Alpes, CEA, IRIG, MEM, Grenoble, 38000, France
| | - Janusz Lewiński
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw, 01-224, Poland
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, Warsaw, 00-664, Poland
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5
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Chen Q, Hu Y, Lin J, Huang J, Gong SL, Xie G. Phenethylammonium bromide interlayer for high-performance red quantum-dot light emitting diodes. NANOSCALE HORIZONS 2024; 9:465-471. [PMID: 38224192 DOI: 10.1039/d3nh00495c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2024]
Abstract
Interfacial modification is vital to boost the performance of colloidal quantum-dot light-emitting diodes (QLEDs). We introduce phenethylammonium bromide (PEABr) as an interlayer to reduce the trap states and exciton quenching at the interface between the emitting layer (EML) with CdSe/ZnS quantum-dots and the electron transport layer (ETL) with ZnMgO. The presence of PEABr separates the EML and the ETL and thus passivates the surface traps of ZnMgO. Moreover, the interfacial modification also alleviates electron injection, leading to more improved carrier injection balance. Consequently, the external quantum efficiency of the PEABr-based red QLED reached 27.6%, which outperformed those of the previously reported devices. Our results indicate that the halide ion salts are promising to balance charge carrier injection and reduce exciton quenching in the QLEDs.
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Affiliation(s)
- Qiyin Chen
- Sauvage Center for Molecular Sciences, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, China.
- The Institute of Flexible Electronics (Future Technologies), Xiamen University, Xiamen 361005, China
| | - Yun Hu
- Oxford Suzhou Centre for Advanced Research (OSCAR), University of Oxford, Suzhou 215123, China.
| | - Jie Lin
- Oxford Suzhou Centre for Advanced Research (OSCAR), University of Oxford, Suzhou 215123, China.
| | - Jingsong Huang
- Oxford Suzhou Centre for Advanced Research (OSCAR), University of Oxford, Suzhou 215123, China.
| | - Shu-Ling Gong
- Sauvage Center for Molecular Sciences, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, China.
| | - Guohua Xie
- Sauvage Center for Molecular Sciences, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, China.
- The Institute of Flexible Electronics (Future Technologies), Xiamen University, Xiamen 361005, China
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Jia S, Hu M, Gu M, Ma J, Li D, Xiang G, Liu P, Wang K, Servati P, Ge WK, Sun XW. Optimizing ZnO-Quantum Dot Interface with Thiol as Ligand Modification for High-Performance Quantum Dot Light-Emitting Diodes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023:e2307298. [PMID: 37972284 DOI: 10.1002/smll.202307298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 10/16/2023] [Indexed: 11/19/2023]
Abstract
As the electron transport layer in quantum dot light-emitting diodes (QLEDs), ZnO suffers from excessive electrons that lead to luminescence quenching of the quantum dots (QDs) and charge-imbalance in QLEDs. Therefore, the interplay between ZnO and QDs requires an in-depth understanding. In this study, DFT and COSMOSL simulations are employed to investigate the effect of sulfur atoms on ZnO. Based on the simulations, thiol ligands (specifically 2-hydroxy-1-ethanethiol) to modify the ZnO nanocrystals are adopted. This modification alleviates the excess electrons without causing any additional issues in the charge injection in QLEDs. This modification strategy proves to be effective in improving the performance of red-emitting QLEDs, achieving an external quantum efficiency of over 23% and a remarkably long lifetime T95 of >12 000 h at 1000 cd m-2 . Importantly, the relationship between ZnO layers with different electronic properties and their effect on the adjacent QDs through a single QD measurement is investigated. These findings show that the ZnO surface defects and electronic properties can significantly impact the device performance, highlighting the importance of optimizing the ZnO-QD interface, and showcasing a promising ligand strategy for the development of highly efficient QLEDs.
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Affiliation(s)
- Siqi Jia
- Institute of Nanoscience and Applications, and Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
- Institute of Advanced Displays and Imaging, Henan Academy of Sciences, Zhengzhou, 450046, China
- Peng Cheng Laboratory, Shenzhen, 518038, China
| | - Menglei Hu
- Institute of Nanoscience and Applications, and Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Mi Gu
- Institute of Nanoscience and Applications, and Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Jingrui Ma
- Institute of Nanoscience and Applications, and Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Depeng Li
- Institute of Nanoscience and Applications, and Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Guohong Xiang
- Institute of Nanoscience and Applications, and Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Pai Liu
- Institute of Nanoscience and Applications, and Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
- Shenzhen Key Laboratory of Deep Subwavelength Scale Photonics, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Kai Wang
- Institute of Nanoscience and Applications, and Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Peyman Servati
- Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Wei Kun Ge
- Institute of Nanoscience and Applications, and Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Xiao Wei Sun
- Institute of Nanoscience and Applications, and Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
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Wang Y, Yang Y, Zhang D, Zhang T, Xie S, Zhang Y, Zhao YB, Mi X, Liu X. Phosphorescent-Dye-Sensitized Quantum-Dot Light-Emitting Diodes with 37% External Quantum Efficiency. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2306703. [PMID: 37722690 DOI: 10.1002/adma.202306703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 09/15/2023] [Indexed: 09/20/2023]
Abstract
Exciton harvesting is of paramount importance for quantum-dot light-emitting diodes (QLEDs). Direct exciton harvesting by the quantum dots (QDs) emitting layer suffers from poor hole injection due to the low conduction bands and valence bands of QDs, leading to unbalanced electron-hole injection and recombination. To address this issue, here, an exciton sensitizing approach is reported, where excitons form on a phosphorescent-dye-doped layer, which then transfer their energies to adjacent QDs layer for photon emission. Due to the very efficient exciton formation and energy-transfer processes, higher device performance can be achieved. To demonstrate the above strategy, red QLEDs with a phosphorescent dye, iridium (III) bis(2-methyldibenzo-[f,h]quinoxaline) (acetylacetonate), Ir(MDQ)2 (acac), doped hole-transporting layer are fabricated and studied. At a doping concentration of 10 wt%, the best device achieves record high current efficiency, power efficiency, and external quantum efficiency (EQE) of 37.3 cd A-1 , 41 lm W-1 , and 37%, respectively. Simultaneously, the efficiency roll-off characteristic is greatly improved, in that 35% EQE can be well retained at a high luminance level of 450 000 cd m-2 . Moreover, the devices also exhibit good stability and reproducibility.
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Affiliation(s)
- Yanping Wang
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun, 130022, P. R. China
- Chongqing Research Institute, Changchun University of Science and Technology, No. 618 Liangjiang Avenue, Longxing Town, Yubei District, Chongqing City, 401135, P. R. China
- Engineering Research Center of Optoelectronic Functional Materials, Ministry of Education, Changchun, 130022, P. R. China
| | - Yusen Yang
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun, 130022, P. R. China
- Engineering Research Center of Optoelectronic Functional Materials, Ministry of Education, Changchun, 130022, P. R. China
| | - Dingke Zhang
- School of Physics and Electronic Engineering, Chongqing Normal University, Chongqing, 401331, P. R. China
| | - Tong Zhang
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun, 130022, P. R. China
- Engineering Research Center of Optoelectronic Functional Materials, Ministry of Education, Changchun, 130022, P. R. China
| | - Shiyi Xie
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun, 130022, P. R. China
- Engineering Research Center of Optoelectronic Functional Materials, Ministry of Education, Changchun, 130022, P. R. China
| | - Yu Zhang
- State Key Laboratory of Integrated Optoelectronics and College of Electronic Science and Engineering, Jilin University, Changchun, 130012, P. R. China
| | - Yong-Biao Zhao
- Key Laboratory of Yunnan Provincial Higher Education Institutions for Optoelectronics Device Engineering, Department of Physics, School of Physics and Astronomy, Yunnan University, Kunming, 650091, China
- International Joint Research Center for Optoelectronic and Engineering Research, Yunnan University, Kunming, 650091, China
| | - Xiaoyun Mi
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun, 130022, P. R. China
- Chongqing Research Institute, Changchun University of Science and Technology, No. 618 Liangjiang Avenue, Longxing Town, Yubei District, Chongqing City, 401135, P. R. China
- Engineering Research Center of Optoelectronic Functional Materials, Ministry of Education, Changchun, 130022, P. R. China
| | - Xiuling Liu
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun, 130022, P. R. China
- Chongqing Research Institute, Changchun University of Science and Technology, No. 618 Liangjiang Avenue, Longxing Town, Yubei District, Chongqing City, 401135, P. R. China
- Engineering Research Center of Optoelectronic Functional Materials, Ministry of Education, Changchun, 130022, P. R. China
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Abstract
Quantum dot light-emitting diodes (QD-LEDs) are one of the most promising self-emissive displays in terms of light-emitting efficiency, wavelength tunability, and cost. Future applications using QD-LEDs can cover a range from a wide color gamut and large panel displays to augmented/virtual reality displays, wearable/flexible displays, automotive displays, and transparent displays, which demand extreme performance in terms of contrast ratio, viewing angle, response time, and power consumption. The efficiency and lifetime have been improved by tailoring the QD structures and optimizing the charge balance in charge transport layers, resulting in theoretical efficiency for unit devices. Currently, longevity and inkjet-printing fabrication of QD-LEDs are being tested for future commercialization. In this Review, we summarize significant progress in the development of QD-LEDs and describe their potential compared to other displays. Furthermore, the critical elements to determine the performance of QD-LEDs, such as emitters, hole/electron transport layers, and device structures, are discussed comprehensively, and the degradation mechanisms of the devices and the issues of the inkjet-printing process were also investigated.
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Affiliation(s)
- Eunjoo Jang
- Material Research Center, Samsung Advanced Institute of Technology, Samsung Electronics, 130 Samsung-ro, Suwon, Gyeonggi-do 16678, Republic of Korea
| | - Hyosook Jang
- Material Research Center, Samsung Advanced Institute of Technology, Samsung Electronics, 130 Samsung-ro, Suwon, Gyeonggi-do 16678, Republic of Korea
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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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Eun YB, Jang GP, Yang JH, Kim SY, Chae YB, Ha MY, Moon DG, Kim CK. Performance Improvement of Quantum Dot Light-Emitting Diodes Using a ZnMgO Electron Transport Layer with a Core/Shell Structure. MATERIALS (BASEL, SWITZERLAND) 2023; 16:600. [PMID: 36676338 PMCID: PMC9862654 DOI: 10.3390/ma16020600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 12/22/2022] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
Highly efficient and all-solution processed quantum dot light-emitting diodes (QLEDs) with high performance are demonstrated by employing ZnMgO nanoparticles (NPs) with core/shell structure used as an electron transport layer (ETL). Mg-doping in ZnO NPs exhibits a different electronic structure and degree of electron mobility. A key processing step for synthesizing ZnMgO NPs with core/shell structure is adding Mg in the solution in addition to the remaining Mg and Zn ions after the core formation process. This enhanced Mg content in the shell layer compared with that of the core X-ray photoelectron spectroscopy showed a higher number of oxygen vacancies for the ZnMgO core/shell structure, thereby enhancing the charge balance in the emitting layer and improving device efficiency. The QLED incorporating the as synthesized ZnMgO NP core/shell A exhibited a maximum luminance of 55,137.3 cd/m2, maximum current efficiency of 58.0 cd/A and power efficiency of 23.3 lm/W. The maximum current efficiency and power efficiency of the QLED with ZnMgO NP core/shell A improved by as much as 156.3% and 113.8%, respectively, compared to the QLED with a Zn0.9Mg0.1O NP ETL, thus demonstrating the benefits of ZnMgO NPs with the specified core/shell structure.
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Affiliation(s)
- Ye-Bin Eun
- Department of Electronic Materials, Devices and Equipment Engineering, Soonchunhyang University, Asan 31538, Chungnam, Republic of Korea
| | - Gyeong-Pil Jang
- Department of Electronic Materials, Devices and Equipment Engineering, Soonchunhyang University, Asan 31538, Chungnam, Republic of Korea
| | - Ji-Hun Yang
- Department of Electronic Materials, Devices and Equipment Engineering, Soonchunhyang University, Asan 31538, Chungnam, Republic of Korea
| | - Su-Young Kim
- Department of Electronic Materials, Devices and Equipment Engineering, Soonchunhyang University, Asan 31538, Chungnam, Republic of Korea
| | - Young-Bin Chae
- Department of Electronic Materials, Devices and Equipment Engineering, Soonchunhyang University, Asan 31538, Chungnam, Republic of Korea
| | - Mi-Young Ha
- Display New Technology Institute, Soonchunhyang University, Asan 31538, Chungnam, Republic of Korea
| | - Dae-Gyu Moon
- Department of Electronic Materials, Devices and Equipment Engineering, Soonchunhyang University, Asan 31538, Chungnam, Republic of Korea
- Display New Technology Institute, Soonchunhyang University, Asan 31538, Chungnam, Republic of Korea
| | - Chang-Kyo Kim
- Department of Electronic Materials, Devices and Equipment Engineering, Soonchunhyang University, Asan 31538, Chungnam, Republic of Korea
- Display New Technology Institute, Soonchunhyang University, Asan 31538, Chungnam, Republic of Korea
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11
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Wang D, Huang JH, Liu HL, Peng W, Zou SH, Miao ZP, Chen XM, Zhang Y. Highly efficient blue quantum-dot light-emitting diodes based on a mixed composite of a carbazole donor and a triazine acceptor as the hole transport layer. Phys Chem Chem Phys 2022; 24:16148-16155. [PMID: 35748470 DOI: 10.1039/d2cp01777f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Solution-processed thermally activated delayed fluorescence (TADF) exciplexes were employed as the hole transport layer (HTL) of blue quantum dot (QD) light-emitting diodes (QLEDs) by blending polymer donors of poly(N-vinylcarbazole) (PVK) with small molecular acceptors of 2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine (T2T). As a result, the PVK:T2T HTL can harvest holes and electrons leaking from the QD active layer to form exciplex excitons and then this harvested exciton energy can be effectively transferred to the adjacent QD emitters through the Förster resonance energy-transfer process. Furthermore, the TADF exciplexes can enhance the hole mobility of the HTL due to the charge transfer process from the PVK donor to the T2T acceptor under an external electric field. The maximum current efficiency (CE) and external quantum efficiency (EQE) of the fabricated blue ZnCdS/ZnS core/shell QLEDs increase from 4.14 cd A-1 and 7.33% for the PVK HTL to 7.73 cd A-1 and 13.66% for the PVK:(5 wt%)T2T HTL, respectively. Our results demonstrate that the TADF exciplex HTL would be a facile strategy to design high-performance blue QLEDs.
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Affiliation(s)
- Dan Wang
- School of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China.
| | - Jia-Hui Huang
- School of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China.
| | - Hong-Liang Liu
- School of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China.
| | - Wen Peng
- School of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China.
| | - Shu-Hua Zou
- School of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China.
| | - Zi-Peng Miao
- School of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China.
| | - Xin-Man Chen
- School of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China.
| | - Yong Zhang
- School of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, P. R. China. .,Guangdong Engineering Technology Research Center of Low Carbon and Advanced Energy Materials, Guangzhou 510631, P. R. China
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12
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Fang Y, Bai P, Li J, Xiao B, Wang Y, Wang Y. Highly Efficient Red Quantum Dot Light-Emitting Diodes by Balancing Charge Injection and Transport. ACS APPLIED MATERIALS & INTERFACES 2022; 14:21263-21269. [PMID: 35486114 DOI: 10.1021/acsami.2c04369] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Quantum dot light-emitting diodes (QLEDs) have promising commercial value and application prospects in the fields of displays and lighting. However, a charge-transfer imbalance always exists in the devices. In this work, the high-efficiency red QLEDs were obtained via employing the mixtures of poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-butylphenyl) (TFB) and 4,4'-bis(carbazole-9-yl)-1,1'-biphenyl (CBP) as hole-transport layers (HTLs) by solution processing. The optimized mixing concentration of CBP is 20 wt %. The corresponding red QLED exhibited a maximum luminance of 963 433 cd m-2, a maximum current efficiency of 38.7 cd A-1, an external quantum efficiency of 30.0%, a central wavelength of 628 nm with a narrow full width at half-maximum (fwhm) of 24 nm, and a 5-fold T50 lifetime enhancement at an extremely high luminance of 200 000 cd m-2. The characteristics of carrier-only devices with QD emissive layers (QD EMLs) and impedance characteristics of QLEDs demonstrate that these advances are chiefly ascribed to the more balanced charge transport and efficient hole-electron recombination in EML. We anticipate that our results could offer a low-cost and simple solution-processed method for preparing high-performance QLEDs.
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Affiliation(s)
- Yunfeng Fang
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, People's Republic of China
| | - Penglong Bai
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, People's Republic of China
| | - Jiayi Li
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, People's Republic of China
| | - Binbin Xiao
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, People's Republic of China
| | - Yiqing Wang
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, People's Republic of China
| | - Yanping Wang
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, People's Republic of China
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13
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Hilal M, Yang W. A dual-functional flexible sensor based on defects-free Co-doped ZnO nanorods decorated with CoO clusters towards pH and glucose monitoring of fruit juices and human fluids. NANO CONVERGENCE 2022; 9:14. [PMID: 35316419 PMCID: PMC8941038 DOI: 10.1186/s40580-022-00305-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 03/06/2022] [Indexed: 05/06/2023]
Abstract
Herein, ZnO nanorods were doped with Co and decorated with CoO clusters through an in situ technique to create a CoO/Co-doped ZnO (CO/CZO) heterostructure at low temperatures (150 °C) on a flexible PET substrate. In the CO/CZO heterostructure, the Co dopant has a low energy barrier to substitute Zn atoms and adsorb over oxygen atoms and their vacancies. Therefore, it decreased the charge density (ND = 2.64 × 1019 cm-3) on non-active sites of ZnO and lowered the charge transfer resistance (317 Ω) at Co-doped-ZnO/electrolyte interface by suppressing the native defects and reducing the Schottky barrier height (- 0.35 eV), respectively. Furthermore, CoO clusters induced a p-n heterostructure with Co-doped ZnO, prevented corrosion, increased the active sites for analyte absorption, and increased the ultimate tensile strength (4.85 N m-2). These characteristics enabled the CO/CZO heterostructure to work as a highly sensitive, chemically stable, and flexible pH and glucose oxidation electrode. Therefore, CO/CZO heterostructure was explored for pH monitoring in human fluids and fruit juices, demonstrating a near-Nernst-limit pH sensitivity (52 mV/pH) and fast response time (19 s) in each human fluid and fruit juice. Also, it demonstrated high sensitivity (4656 µM mM-1 cm-2), low limit of detection (0.15 µM), a broad linear range (0.04 mM to 8.85 mM) and good anti-interference capacity towards glucose-sensing. Moreover, it demonstrated excellent flexibility performances, retained 53% and 69% sensitivity of the initial value for pH and glucose sensors, respectively, after 500 bending, stretching, and warping cycles.
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Affiliation(s)
- Muhammad Hilal
- Department of Physics, Dongguk University, Seoul, 04620, Republic of Korea
| | - Woochul Yang
- Department of Physics, Dongguk University, Seoul, 04620, Republic of Korea.
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14
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Metal oxide charge transfer complex for effective energy band tailoring in multilayer optoelectronics. Nat Commun 2022; 13:75. [PMID: 35013208 PMCID: PMC8748812 DOI: 10.1038/s41467-021-27652-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Accepted: 11/30/2021] [Indexed: 11/17/2022] Open
Abstract
Metal oxides are intensively used for multilayered optoelectronic devices such as organic light-emitting diodes (OLEDs). Many approaches have been explored to improve device performance by engineering electrical properties. However, conventional methods cannot enable both energy level manipulation and conductivity enhancement for achieving optimum energy band configurations. Here, we introduce a metal oxide charge transfer complex (NiO:MoO3-complex), which is composed of few-nm-size MoO3 domains embedded in NiO matrices, as a highly tunable carrier injection material. Charge transfer at the finely dispersed interfaces of NiO and MoO3 throughout the entire film enables effective energy level modulation over a wide work function range of 4.47 – 6.34 eV along with enhanced electrical conductivity. The high performance of NiO:MoO3-complex is confirmed by achieving 189% improved current efficiency compared to that of MoO3-based green OLEDs and also an external quantum efficiency of 17% when applied to blue OLEDs, which is superior to 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile-based conventional devices. One pathway for improving the performance of optoelectronics is the tailoring energy bands of the charge transport layer. Here, Kim et al present a charge transfer complex composed out of nanodomains of MoO3 embedded within an NiO matrix, significantly improving green and blue OLED performance.
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15
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Dong JY, Ng KW, Song YM, Li JL, Kong YC, Wang MW, Xu JC, Li L, Chen S, Tang ZK, Wang SP. Observation and Suppression of Stacking Interface States in Sandwich-Structured Quantum Dot Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2021; 13:56630-56637. [PMID: 34794311 DOI: 10.1021/acsami.1c13052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Interfacial quality of functional layers plays an important role in the carrier transport of sandwich-structured devices. Although the suppression of interface states is crucial to the overall device performance, our understanding on their formation and annihilation mechanism via direct characterization is still quite limited. Here, we present a thorough study on the interface states present in the electron transport layer (ETL) of blue quantum dot (QD) light-emitting diodes (QLEDs). A ZnO/ZnMgO bilayer ETL is adopted to enhance the electron injection into blue QDs. By probing the ETL band structure with photoelectron spectroscopy, we discover that substantial band bending exists at the ZnO/ZnMgO interface, elucidating the presence of a high density of interface states which hinder electron transport. By inserting a ZnO@ZMO interlayer composed of mixed ZnO and ZnMgO nanoparticles, the band bending and thus the interface states are observed to reduce significantly. We attribute this to the hybrid surface properties of ZnO@ZMO, which can annihilate the surface states of both the ZnO and ZnMgO layers. The introduction of a bridging layer has led to ∼40% enhancement in the power efficiency of blue QLEDs and noticeable performance boosts in green and red QLEDs. The findings here demonstrate a direct observation of interface states via detailed band structure studies and outline a potential pathway for eliminating these states for better performances in sandwich-structured devices.
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Affiliation(s)
- Jia-Yi Dong
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macao, SAR 999078, China
| | - Kar Wei Ng
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macao, SAR 999078, China
| | - Yin-Man Song
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macao, SAR 999078, China
| | - Jie-Lei Li
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macao, SAR 999078, China
| | - You-Chao Kong
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macao, SAR 999078, China
| | - Meng-Wei Wang
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macao, SAR 999078, China
| | - Jin-Cheng Xu
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macao, SAR 999078, China
| | - Lin Li
- Key Laboratory for Photonic and Electronic Bandgap Materials, Ministry of Education, School of Physics & Electron Engineering, Harbin Normal University, Harbin 150025, China
| | - Shi Chen
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macao, SAR 999078, China
| | - Zi-Kang Tang
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macao, SAR 999078, China
| | - Shuang-Peng Wang
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macao, SAR 999078, China
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16
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Chen WS, Yang SH, Tseng WC, Chen WWS, Lu YC. Utilization of Nanoporous Nickel Oxide as the Hole Injection Layer for Quantum Dot Light-Emitting Diodes. ACS OMEGA 2021; 6:13447-13455. [PMID: 34056492 PMCID: PMC8158834 DOI: 10.1021/acsomega.1c01618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 04/29/2021] [Indexed: 06/10/2023]
Abstract
Nickel oxide (NiOx) has been extensively investigated as the hole injection layer (HIL) for many optoelectronic devices because of its excellent hole mobility, high environmental stability, and low-cost fabrication. In this research, a NiOx thin film and nanoporous layers (NPLs) have been utilized as the HIL for the fabrication of quantum dot light-emitting diodes (QLEDs). The obtained NiOx NPLs have spongelike nanostructures that possess a larger surface area to enhance carrier injection and to lower the turn-on voltage as compared with the NiOx thin film. The energy levels of NiOx were slightly downshifted by incorporating the nanoporous structure. The amount of Ni2O3 species is higher than that of NiO in the NiOx NPL, confirming its good hole transport ability. The best QLED was achieved with a 30 nm thick NiOx NPL, exhibiting a maximum brightness of 68 646 cd m-2, a current efficiency of 7.60 cd A-1, and a low turn-on voltage of 3.4 V. More balanced carrier transport from the NiOx NPL and ZnO NPs/polyethylenimine ethoxylated (PEIE) is responsible for the improved device performance.
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Affiliation(s)
- Wei-Sheng Chen
- Institute
of Lighting and Energy Photonics, College of Photonics, National Chiao Tung University, No. 301, Gaofa 3rd Road, Guiren District, Tainan 71150, Taiwan, ROC
| | - Sheng-Hsiung Yang
- Institute
of Lighting and Energy Photonics, College of Photonics, National Chiao Tung University, No. 301, Gaofa 3rd Road, Guiren District, Tainan 71150, Taiwan, ROC
| | - Wei-Cheng Tseng
- Opulence
Optronics Co., Ltd., 3F, No. 1, Zhanye 1st Road, East District, Hsinchu 30091, Taiwan, ROC
| | - Wilson Wei-Sheng Chen
- Opulence
Optronics Co., Ltd., 3F, No. 1, Zhanye 1st Road, East District, Hsinchu 30091, Taiwan, ROC
| | - Yuan-Chang Lu
- Opulence
Optronics Co., Ltd., 3F, No. 1, Zhanye 1st Road, East District, Hsinchu 30091, Taiwan, ROC
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17
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Kim HM, Jeong W, Kim JH, Jang J. Stability of Quantum-Dot Light Emitting Diodes with Alkali Metal Carbonates Blending in Mg Doped ZnO Electron Transport Layer. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E2423. [PMID: 33291578 PMCID: PMC7761844 DOI: 10.3390/nano10122423] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 11/30/2020] [Accepted: 12/02/2020] [Indexed: 11/30/2022]
Abstract
We report here the fabrication of highly efficient and long-lasting quantum-dot light emitting diodes (QLEDs) by blending various alkali metal carbonate in magnesium (Mg) doped zinc oxide (ZnO) (MZO) electron transport layer (ETL). Alkali metal carbonates blending in MZO, X2CO3:MZO, control the band-gap, electrical properties, and thermal stability. This can therefore enhance the operational lifetime of QLEDs. It is found that the conductivity of X2CO3:MZO film can be controlled and the thermal stability of ETLs could be improved by X2CO3 blending in MZO. The inverted red QLEDs (R-QLEDs) with Cs2CO3:MZO, Rb2CO3:MZO, and K2CO3:MZO ETLs exhibited the operational lifetime of 407 h for the R-QLEDs with Cs2CO3:MZO, 620 h with Rb2CO3:MZO and 94 h with K2CO3:MZO ETLs at T95 with the initial luminance of 1000 cd/m2. Note that all red QLEDs showed the high brightness over 150,000 cd/m2. But the R-QLEDs with Na2CO3:MZO and Li2CO3:MZO ETLs exhibited shorter operational lifetime and poor brightness than the R-QLED with pristine MZO ETL.
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Affiliation(s)
| | | | | | - Jin Jang
- Department of Information Display and Advanced Display Research Center, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 02447, Korea; (H.-M.K.); (W.J.); (J.H.K.)
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18
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Jia H, Wang F, Tan Z. Material and device engineering for high-performance blue quantum dot light-emitting diodes. NANOSCALE 2020; 12:13186-13224. [PMID: 32614007 DOI: 10.1039/d0nr02074e] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Colloidal quantum dots (QDs) have attracted extensive attention due to their excellent optoelectronic properties, such as high quantum efficiency, narrow emission peaks, high color saturation, high stability and solution processability. Compared with the traditional display technology, QD based light-emitting diodes (QLEDs) show broad application prospects in the field of flat-panel displays and solid-state lighting. However, for full-color displays, the efficiency and lifetime of blue QLEDs are inferior to those of their green and red counterparts. Therefore, it is urgent for us to deeply understand the device physics and improve the performance of blue QLEDs through material and device engineering. An in-depth understanding of the optoelectronic properties (such as the structure of electronic states, electron-phonon interactions, Auger processes, etc.) and material engineering (such as size distribution control, composition control, and surface engineering) of blue emission QDs is greatly helpful for their applications in other fields. Herein, we review the key progress in the area of blue QLEDs, including the compositions and nanostructures of blue quantum dots, advances in the device architectures and the improvement of the device lifetime of blue QLEDs. The key factors that influence the blue device performance, including the nanostructure design and surface modification of QDs, interface engineering and architecture design of devices are discussed, aiming to propose possible solutions for these challenges, which will help to promote the commercialization process of QLEDs.
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Affiliation(s)
- Haoran Jia
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Fuzhi Wang
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
| | - Zhan'ao Tan
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
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19
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Wang X, Chen X, Wang X, Hu J, Wu Y, Zhang WH. Surface polarity engineering of ZnO layer for improved photoluminescence of CsPbBr3 quantum dot films. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137454] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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20
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Alexandrov A, Zvaigzne M, Lypenko D, Nabiev I, Samokhvalov P. Al-, Ga-, Mg-, or Li-doped zinc oxide nanoparticles as electron transport layers for quantum dot light-emitting diodes. Sci Rep 2020; 10:7496. [PMID: 32366882 PMCID: PMC7198560 DOI: 10.1038/s41598-020-64263-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 04/14/2020] [Indexed: 11/09/2022] Open
Abstract
Colloidal quantum dots and other semiconductor nanocrystals are essential components of next-generation lighting and display devices. Due to their easily tunable and narrow emission band and near-unity fluorescence quantum yield, they allow cost-efficient fabrication of bright, pure-color and wide-gamut light emitting diodes (LEDs) and displays. A critical improvement in the quantum dot LED (QLED) technology was achieved when zinc oxide nanoparticles (NPs) were first introduced as an electron transport layer (ETL) material, which tremendously enhanced the device brightness and current efficiency due to the high mobility of electrons in ZnO and favorable alignment of its energy bands. During the next decade, the strategy of ZnO NP doping allowed the fabrication of QLEDs with a brightness of about 200 000 cd/m2 and current efficiency over 60 cd/A. On the other hand, the known ZnO doping approaches rely on a very fine tuning of the energy levels of the ZnO NP conduction band minimum; hence, selection of the appropriate dopant that would ensure the best device characteristics is often ambiguous. Here we address this problem via detailed comparison of QLEDs whose ETLs are formed by a set of ZnO NPs doped with Al, Ga, Mg, or Li. Although magnesium-doped ZnO NPs are the most common ETL material used in recently designed QLEDs, our experiments have shown that their aluminum-doped counterparts ensure better device performance in terms of brightness, current efficiency and turn-on voltage. These findings allow us to suggest ZnO NPs doped with Al as the best ETL material to be used in future QLEDs.
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Affiliation(s)
- Alexei Alexandrov
- Laboratory of Nano-Bioengineering, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Moscow, Russian Federation
- Laboratory of Electronic and Photonic Processes in Polymeric Nanostructural Materials, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences, 119071, Moscow, Russian Federation
| | - Mariya Zvaigzne
- Laboratory of Nano-Bioengineering, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Moscow, Russian Federation
| | - Dmitri Lypenko
- Laboratory of Nano-Bioengineering, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Moscow, Russian Federation
- Laboratory of Electronic and Photonic Processes in Polymeric Nanostructural Materials, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences, 119071, Moscow, Russian Federation
| | - Igor Nabiev
- Laboratory of Nano-Bioengineering, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Moscow, Russian Federation.
- Laboratoire de Recherche en Nanosciences, LRN-EA4682, Université de Reims Champagne-Ardenne, 51100, Reims, France.
- I.M. Sechenov First Moscow State Medical University, 119991, Moscow, Russian Federation.
| | - Pavel Samokhvalov
- Laboratory of Nano-Bioengineering, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Moscow, Russian Federation.
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21
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Liu D, Cao S, Wang S, Wang H, Dai W, Zou B, Zhao J, Wang Y. Highly Stable Red Quantum Dot Light-Emitting Diodes with Long T95 Operation Lifetimes. J Phys Chem Lett 2020; 11:3111-3115. [PMID: 32249583 DOI: 10.1021/acs.jpclett.0c00836] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Quantum dot light-emitting diodes (QLEDs) with an excellent external quantum efficiency (EQE) and an excellent lifetime almost meet the requirements for low-brightness displays. However, the short operation lifetime under high brightness limits the application of QLEDs in outdoor displays and lightings. Herein, we report a highly efficient, stable red QLED using co-doped lithium and magnesium as well as a magnesium oxide shell-coated zinc oxide nanoparticle layer as an electron transport layer (ETL). The optimized QLED has a high peak EQE of 20.6%, a low efficiency roll-off at high current, and a remarkably long lifetime T95 of >11000 h at 1000 cd m-2, which is an indication of the realization of the most stable red QLED to date. The improvement in the long term stability of the QLED is attributed to the use of a co-doped and shell-coated zinc oxide ETL with a reduced level of electron injection to improve the charge balance in the device.
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Affiliation(s)
- Dongqiang Liu
- Suzhou Xingshuo Nanotech Company, Ltd. (Mesolight), Suzhou 215123, China
| | - Sheng Cao
- School of Physical Science and Technology, Key Laboratory of New Processing Technology for Nonferrous Metals and Materials (Ministry of Education), State Key Laboratory of Processing for Non-Ferrous Metal and Featured Materials, Guangxi University, Nanning 530004, China
| | - Siyuan Wang
- Suzhou Xingshuo Nanotech Company, Ltd. (Mesolight), Suzhou 215123, China
| | - Hongqin Wang
- Suzhou Xingshuo Nanotech Company, Ltd. (Mesolight), Suzhou 215123, China
| | - Wei Dai
- Suzhou Xingshuo Nanotech Company, Ltd. (Mesolight), Suzhou 215123, China
| | - Bingsuo Zou
- School of Physical Science and Technology, Key Laboratory of New Processing Technology for Nonferrous Metals and Materials (Ministry of Education), State Key Laboratory of Processing for Non-Ferrous Metal and Featured Materials, Guangxi University, Nanning 530004, China
| | - Jialong Zhao
- School of Physical Science and Technology, Key Laboratory of New Processing Technology for Nonferrous Metals and Materials (Ministry of Education), State Key Laboratory of Processing for Non-Ferrous Metal and Featured Materials, Guangxi University, Nanning 530004, China
| | - Yunjun Wang
- Suzhou Xingshuo Nanotech Company, Ltd. (Mesolight), Suzhou 215123, China
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22
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Li Y, Liu X, Wen D, Lv K, Zhou G, Zhao Y, Xu C, Wang J. Growth of c-plane and m-plane aluminium-doped zinc oxide thin films: epitaxy on flexible substrates with cubic-structure seeds. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2020; 76:233-240. [PMID: 32831225 DOI: 10.1107/s2052520620002668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 02/26/2020] [Indexed: 06/11/2023]
Abstract
Manufacturing high-quality zinc oxide (ZnO) devices demands control of the orientation of ZnO materials due to the spontaneous and piezoelectric polarity perpendicular to the c-plane. However, flexible electronic and optoelectronic devices are mostly built on polymers or glass substrates which lack suitable epitaxy seeds for the orientation control. Applying cubic-structure seeds, it was possible to fabricate polar c-plane and nonpolar m-plane aluminium-doped zinc oxide (AZO) films epitaxially on flexible Hastelloy substrates through minimizing the lattice mismatch. The growth is predicted of c-plane and m-plane AZO on cubic buffers with lattice parameters of 3.94-4.63 Å and 5.20-5.60 Å, respectively. The ∼80 nm-thick m-plane AZO film has a resistivity of ∼11.43 ± 0.01 × 10-4 Ω cm, while the c-plane AZO film shows a resistivity of ∼2.68 ± 0.02 × 10-4 Ω cm comparable to commercial indium tin oxide films. An abnormally higher carrier concentration in the c-plane than in the m-plane AZO film results from the electrical polarity along the c-axis. The resistivity of the c-plane AZO film drops to the order of 10-5 Ω cm at 500 K owing to the semiconducting behaviour. Epitaxial AZO films with low resistivities and controllable orientations on flexible substrates offer optimal transparent electrodes and epitaxy seeds for high-performance flexible ZnO devices.
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Affiliation(s)
- Yongkuan Li
- Research Center for Advanced Optics and Photoelectronics, and Department of Physics, College of Science, Shantou University, Daxue Lu #243, Shantou, Guangdong 515063, People's Republic of China
| | - Xinxing Liu
- Research Center for Advanced Optics and Photoelectronics, and Department of Physics, College of Science, Shantou University, Daxue Lu #243, Shantou, Guangdong 515063, People's Republic of China
| | - Dan Wen
- Research Center for Advanced Optics and Photoelectronics, and Department of Physics, College of Science, Shantou University, Daxue Lu #243, Shantou, Guangdong 515063, People's Republic of China
| | - Kai Lv
- Research Center for Advanced Optics and Photoelectronics, and Department of Physics, College of Science, Shantou University, Daxue Lu #243, Shantou, Guangdong 515063, People's Republic of China
| | - Gang Zhou
- Research Center for Advanced Optics and Photoelectronics, and Department of Physics, College of Science, Shantou University, Daxue Lu #243, Shantou, Guangdong 515063, People's Republic of China
| | - Yue Zhao
- Shanghai Superconductor Technology Co., Ltd, and School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Congkang Xu
- Research Center for Advanced Optics and Photoelectronics, and Department of Physics, College of Science, Shantou University, Daxue Lu #243, Shantou, Guangdong 515063, People's Republic of China
| | - Jiangyong Wang
- Research Center for Advanced Optics and Photoelectronics, and Department of Physics, College of Science, Shantou University, Daxue Lu #243, Shantou, Guangdong 515063, People's Republic of China
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23
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Efficiency enhancement of quantum-dot light-emitting diodes via rapid post-treatment of intense pulsed light sintering technique. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2019.137048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Li D, Kristal B, Wang Y, Feng J, Lu Z, Yu G, Chen Z, Li Y, Li X, Xu X. Enhanced Efficiency of InP-Based Red Quantum Dot Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2019; 11:34067-34075. [PMID: 31441639 DOI: 10.1021/acsami.9b07437] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Due to the inherent toxicity of cadmium selenide (CdSe)-based quantum dots (QDs), Cd-free alternatives are being widely investigated. Indium phosphide (InP) QDs have shown great potential as a replacement for CdSe QDs in display applications. However, the performance of InP-based quantum dot light-emitting diodes (QLEDs) is still far behind that of the CdSe-based devices. In this study, we wanted to show the effects of different approaches to improving the performance of InP-based QLED devices. We investigated the effect of magnesium (Mg) doping in ZnO nanoparticles, which is used as an n-type electron transport layer, in balancing the charge transfer in InP-based QLED devices. We found that an increasing Mg doping level can broaden ZnO band gap, shift its energy levels, but most importantly, increase its resistivity; as a result, the electron current density is significantly reduced and the device efficiency is improved. We also investigated the effect of high-photoluminescence quantum yield emitters and different QLED architectures on the device performance. Through optimizing QD structures and devices, red InP QLEDs with the current efficiencies as high as 11.6 cd/A were fabricated.
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Affiliation(s)
- Dong Li
- BOE Technology Group Co., Ltd. , Beijing 100176 , P. R. China
| | - Boris Kristal
- BOE Technology Group Co., Ltd. , Beijing 100176 , P. R. China
| | - Yunjun Wang
- Suzhou Xingshuo Nanotech Co., Ltd. (Mesolight) , Suzhou 215123 , P. R. China
| | - Jingwen Feng
- BOE Technology Group Co., Ltd. , Beijing 100176 , P. R. China
| | - Zhigao Lu
- BOE Technology Group Co., Ltd. , Beijing 100176 , P. R. China
| | - Gang Yu
- BOE Technology Group Co., Ltd. , Beijing 100176 , P. R. China
| | - Zhuo Chen
- BOE Technology Group Co., Ltd. , Beijing 100176 , P. R. China
| | - Yanzhao Li
- BOE Technology Group Co., Ltd. , Beijing 100176 , P. R. China
| | - Xinguo Li
- BOE Technology Group Co., Ltd. , Beijing 100176 , P. R. China
- School of Software & Microelectronics , Peking University , Beijing 102600 , P. R. China
| | - Xiaoguang Xu
- BOE Technology Group Co., Ltd. , Beijing 100176 , P. R. China
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25
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Song T, Cheong JY, Cho H, Kim ID, Jeon DY. Mixture of quantum dots and ZnS nanoparticles as emissive layer for improved quantum dots light emitting diodes. RSC Adv 2019; 9:15177-15183. [PMID: 35514803 PMCID: PMC9064264 DOI: 10.1039/c9ra01462d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 05/04/2019] [Indexed: 11/21/2022] Open
Abstract
Recently, quantum dots based light-emitting diodes (QLEDs) have received huge attention due to the properties of quantum dots (QDs), such as high photoluminescence quantum yield (PLQY) and narrow emission. To improve the performance of QLEDs, reducing non-radiative energy transfer is critical. So far, most conventional methods required additional chemical treatment like giant shell and/or ligands exchange. However that triggers unsought shifted emission or reduced PLQY of QDs. In this work, we have firstly suggested a novel approach to improve the efficiency of QLEDs by introducing inorganic nanoparticles (NPs) spacer between QDs, without additional chemical treatment. As ZnS NPs formed a mixture layer with QDs, the energy transfer was reduced and the distance between the QDs increased, leading to improved PLQY of mixture layer. As a result, current efficiency (CE) of the QLED device was improved by twice compared with one using only QDs layer. This is an early report on utilizing ZnS NPs as an efficient spacer, which can be utilized to other compositions of QDs. Mixture of quantum dots and ZnS nanoparticles as emissive layer for improved QLEDs by decreasing energy transfer between the QDs.![]()
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Affiliation(s)
- Taeyoung Song
- Department of Materials Science and Engineering
- Korea Advanced Institute of Science and Technology
- Daejeon 305-701
- Republic of Korea
| | - Jun Young Cheong
- Department of Materials Science and Engineering
- Korea Advanced Institute of Science and Technology
- Daejeon 305-701
- Republic of Korea
| | - Hyunjin Cho
- Department of Materials Science and Engineering
- Korea Advanced Institute of Science and Technology
- Daejeon 305-701
- Republic of Korea
| | - Il-Doo Kim
- Department of Materials Science and Engineering
- Korea Advanced Institute of Science and Technology
- Daejeon 305-701
- Republic of Korea
| | - Duk Young Jeon
- Department of Materials Science and Engineering
- Korea Advanced Institute of Science and Technology
- Daejeon 305-701
- Republic of Korea
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26
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Moyen E, Jun H, Kim HM, Jang J. Surface Engineering of Room Temperature-Grown Inorganic Perovskite Quantum Dots for Highly Efficient Inverted Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2018; 10:42647-42656. [PMID: 30419162 DOI: 10.1021/acsami.8b15212] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Inorganic cesium lead bromide quantum dots (CsPbBr3 QDs) are usually synthesized via a high-temperature process (hot injection, HI). This process is similar to that used for the synthesis of other semiconductor QDs (i.e., CdSe@ZnS), which limits their potential cost advantage. CsPbBr3 QDs can also be synthesized at room temperature (RT) in a low cost and easily scalable process, which, thus, is one of the greatest advantages of the CsPbBr3 QDs. However, light-emitting diodes (LEDs) fabricated using RT-QDs exhibit poor performance compared to those of HI-QDs. In fact, QDs are surrounded by insulating ligands to maintain their colloidal stability but these ligands need to be removed to obtain high-performance LEDs. Here, we show that ligand removal techniques used for HI-QDs are not sufficient in the case of RT-QDs. Additional ligand engineering and annealing steps are necessary to remove the excess of ligands from RT-QD films while preventing the coalescence of the QDs. The eventual surface defects induced by annealing can be healed by a subsequent photoactivation step. Moreover, the use of solution processable inorganic charge transport layers can reduce the fabrication costs of LEDs. We fabricated an inverted LED based on a metal oxide electron transport layer and a RT-QD emitting layer which exhibited a maximum current efficiency of 17.61 cd A-1 and a maximum luminance of 22 825 cd m-2.
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Affiliation(s)
- Eric Moyen
- Advanced Display Research Center (ADRC) and Department of Information Display , Kyung Hee University , 26, Kyungheedae-ro , Dongdaemun-gu, Seoul 02447 , South Korea
| | - Haeyeon Jun
- Advanced Display Research Center (ADRC) and Department of Information Display , Kyung Hee University , 26, Kyungheedae-ro , Dongdaemun-gu, Seoul 02447 , South Korea
| | - Hyo-Min Kim
- Advanced Display Research Center (ADRC) and Department of Information Display , Kyung Hee University , 26, Kyungheedae-ro , Dongdaemun-gu, Seoul 02447 , South Korea
| | - Jin Jang
- Advanced Display Research Center (ADRC) and Department of Information Display , Kyung Hee University , 26, Kyungheedae-ro , Dongdaemun-gu, Seoul 02447 , South Korea
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27
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Kathirgamanathan P, Kumaraverl M, Vanga RR, Ravichandran S. Intense pulsed light (IPL) annealed sol-gel derived ZnO electron injector for the production of high efficiency inverted quantum dot light emitting devices (QLEDs). RSC Adv 2018; 8:36632-36646. [PMID: 35558924 PMCID: PMC9088871 DOI: 10.1039/c8ra08136k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 10/22/2018] [Indexed: 12/25/2022] Open
Abstract
Room temperature intense pulsed light annealing (photonic annealing, pulsed forge) renders the sol-gel derived ZnO films highly conductive and hydrophobic with improved interface with the colloidal quantum dots. The IPL annealed ZnO proved to be a better electron transporter/injector in inverted devices with QDs. Both the current and power efficiencies of red devices comprising IPL annealed ZnO were 13.75 and 37.5 fold higher than the identical devices produced with thermally annealed ZnO. The lifetime of the devices with IPL annealed ZnO was found to be fivefold longer than the thermally annealed ZnO counterpart. Thermally aged devices comprising IPL annealed ZnO gave a maximum current efficiency of 23 cd A-1 and a power efficiency of 30 lm W-1.
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Affiliation(s)
| | | | - Raghava Reddy Vanga
- Organic Electronics Group, Wolfson Centre, Brunel University London Uxbridge UB8 3PH UK
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