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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; 20: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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2
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Li S, Xu X, Lin Q, Sun J, Zhang H, Shen H, Li LS, Wang L. Bright and Stable Yellow Quantum Dot Light-Emitting Diodes Through Core-Shell Nanostructure Engineering. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2306859. [PMID: 38155356 DOI: 10.1002/smll.202306859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 12/15/2023] [Indexed: 12/30/2023]
Abstract
Solution-processed and efficient yellow quantum dot light-emitting diodes (QLEDs) are considered key optoelectronic devices for lighting, display, and signal indication. However, limited synthesis routes for yellow quantum dots (QDs), combined with inferior stress-relaxation of the core-shell interface, pose challenges to their commercialization. Herein, a nanostructure tailoring strategy for high-quality yellow CdZnSe/ZnSe/ZnS core/shell QDs using a "stepwise high-temperature nucleation-shell growth" method is introduced. The synthesized CdZnSe-based QDs effectively smoothed the release stress of the core-shell interface and revealed a near-unit photoluminescence quantum yield, with nonblinking behavior and matched energy level, which accelerated radiative recombination and charge injection balance for device operation. Consequently, the yellow CdZnSe-based QLEDs exhibited a peak external quantum efficiency of 23.7%, a maximum luminance of 686 050 cd m-2, and a current efficiency of 103.2 cd A-1, along with an operating half-lifetime of 428 523 h at 100 cd m-2. To the best of the knowledge, the luminance and operational stability of the device are found to be the highest values reported for yellow LEDs. Moreover, devices with electroluminescence (EL) peaks at 570-605 nm exhibited excellent EQEs, surpassing 20%. The work is expected to significantly push the development of RGBY-based display panels and white LEDs.
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Affiliation(s)
- Saifei 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, 475004, China
| | - Xiongping 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, Henan University, Kaifeng, 475004, China
| | - Qingli Lin
- 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, 475004, China
| | - Jiahui 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, 475004, China
| | - Han 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, 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, Henan University, Kaifeng, 475004, China
| | - 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, 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, Henan University, Kaifeng, 475004, 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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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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5
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Nawaz A, Merces L, Ferro LMM, Sonar P, Bufon CCB. Impact of Planar and Vertical Organic Field-Effect Transistors on Flexible Electronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2204804. [PMID: 36124375 DOI: 10.1002/adma.202204804] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 09/13/2022] [Indexed: 06/15/2023]
Abstract
The development of flexible and conformable devices, whose performance can be maintained while being continuously deformed, provides a significant step toward the realization of next-generation wearable and e-textile applications. Organic field-effect transistors (OFETs) are particularly interesting for flexible and lightweight products, because of their low-temperature solution processability, and the mechanical flexibility of organic materials that endows OFETs the natural compatibility with plastic and biodegradable substrates. Here, an in-depth review of two competing flexible OFET technologies, planar and vertical OFETs (POFETs and VOFETs, respectively) is provided. The electrical, mechanical, and physical properties of POFETs and VOFETs are critically discussed, with a focus on four pivotal applications (integrated logic circuits, light-emitting devices, memories, and sensors). It is pointed out that the flexible function of the relatively newer VOFET technology, along with its perspective on advancing the applicability of flexible POFETs, has not been reviewed so far, and the direct comparison regarding the performance of POFET- and VOFET-based flexible applications is most likely absent. With discussions spanning printed and wearable electronics, materials science, biotechnology, and environmental monitoring, this contribution is a clear stimulus to researchers working in these fields to engage toward the plentiful possibilities that POFETs and VOFETs offer to flexible electronics.
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Affiliation(s)
- Ali Nawaz
- Center for Sensors and Devices, Bruno Kessler Foundation (FBK), Trento, 38123, Italy
| | - Leandro Merces
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo, 13083-100, Brazil
| | - Letícia M M Ferro
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo, 13083-100, Brazil
- Institute of Chemistry, University of Campinas, Campinas, São Paulo, 13083-970, Brazil
| | - Prashant Sonar
- School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane, QLD, 4000, Australia
- Centre for Materials Science, Queensland University of Technology, 2 George Street, Brisbane, QLD, 4000, Australia
| | - Carlos C B Bufon
- MackGraphe - Graphene and Nanomaterials Research Center, Mackenzie Presbyterian Institute, São Paulo, 01302-907, Brazil
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6
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Jiang X, Fan Z, Luo L, Wang L. Advances and Challenges in Heavy-Metal-Free InP Quantum Dot Light-Emitting Diodes. MICROMACHINES 2022; 13:mi13050709. [PMID: 35630176 PMCID: PMC9145869 DOI: 10.3390/mi13050709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 02/06/2023]
Abstract
Light-emitting diodes based on colloidal quantum dots (QLEDs) show a good prospect in commercial application due to their narrow spectral linewidths, wide color range, excellent luminance efficiency, and long operating lifetime. However, the toxicity of heavy-metal elements, such as Cd-based QLEDs or Pb-based perovskite QLEDs, with excellent performance, will inevitably pose a serious threat to people’s health and the environment. Among heavy-metal-free materials, InP quantum dots (QDs) have been paid special attention, because of their wide emission, which can, in principle, be tuned throughout the whole visible and near-infrared range by changing their size, and InP QDs are generally regarded as one of the most promising materials for heavy-metal-free QLEDs for the next generation displays and solid-state lighting. In this review, the great progress of QLEDs, based on the fundamental structure and photophysical properties of InP QDs, is illustrated systematically. In addition, the remarkable achievements of QLEDs, based on their modification of materials, such as ligands exchange of InP QDs, and the optimization of the charge transport layer, are summarized. Finally, an outlook is shown about the challenge faced by QLED, as well as possible pathway to enhancing the device performance. This review provides an overview of the recent developments of InP QLED applications and outlines the challenges for achieving the high-performance devices.
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Affiliation(s)
- Xiaojie Jiang
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China; (X.J.); (Z.F.) ; (L.L.)
| | - Zhen Fan
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China; (X.J.); (Z.F.) ; (L.L.)
| | - Li Luo
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China; (X.J.); (Z.F.) ; (L.L.)
| | - Lishuang Wang
- School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China; (X.J.); (Z.F.) ; (L.L.)
- Guangxi Key Lab of Processing for Nonferrous Metals and Featured Materials and Key Lab of New Processing Technology for Nonferrous Metals and Materials, Nanning 530004, China
- Correspondence:
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7
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Wang R, Wang T, Kang Z, Zhang H, Yu R, Ji W. Efficient flexible quantum-dot light-emitting diodes with unipolar charge injection. OPTICS EXPRESS 2022; 30:15747-15756. [PMID: 35473288 DOI: 10.1364/oe.456449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/11/2022] [Indexed: 06/14/2023]
Abstract
The exfoliation between the electrode film and the adjacent functional layer is still a big challenge for the flexible light emitting diodes, especially for the devices dependent on the direct charge injection from the electrodes. To address this issue, we design a flexible quantum-dot light-emitting diodes (QLEDs) with a charge-generation layer (CGL) on the bottom electrode as the electron supplier. The CGL consisting of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/ZnO can provide sufficient electron injection into the QDs, enabling a balanced charge injection. As a result, the CGL-based QLED exhibits a peak external quantum efficiency 18.6%, over 25% enhancement in comparison with the device with ZnO as the electron transport layer. Moreover, the residual electrons in the ZnO can be pulled back to the PEDOT:PSS/ZnO interface by the storage holes in the CGL, which are released and accelerates the electron injection during the next driving voltage pulse, hence improving the electroluminescence response speed of the QLEDs.
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Kim M, Kim D, Kwon O, Lee H. Flexible CdSe/ZnS Quantum-Dot Light-Emitting Diodes with Higher Efficiency than Rigid Devices. MICROMACHINES 2022; 13:mi13020269. [PMID: 35208393 PMCID: PMC8880799 DOI: 10.3390/mi13020269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/01/2022] [Accepted: 02/05/2022] [Indexed: 11/16/2022]
Abstract
Fabrication of high-performance, flexible quantum-dot light-emitting diodes (QLEDs) requires the reliable manufacture of a flexible transparent electrode to replace the conventional brittle indium tin oxide (ITO) transparent electrode, along with flexible substrate planarization. We deposited a transparent oxide/metal/oxide (OMO) electrode on a polymer planarization layer and co-optimized both layers. The visible transmittance of the OMO electrode on a polyethylene terephthalate substrate increased markedly. Good electron supply and injection into an electron-transporting layer were achieved using WOX/Ag/ WOX and MoOx/Ag/MoOX OMO electrodes. High-performance flexible QLEDs were fabricated from these electrodes; a QLED with a MoOX/Ag/ MoOX cathode and an SU-8 planarization layer had a current efficiency of 30.3 cd/A and luminance more than 7 × 104 cd/m2. The current efficiency was significantly higher than that of a rigid QLED with an ITO cathode and was higher than current efficiency values obtained from previously reported QLEDs that utilized the same quantum-dot and electron-transporting layer materials as our study.
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Wu Q, Gong X, Zhao D, Zhao YB, Cao F, Wang H, Wang S, Zhang J, Quintero-Bermudez R, Sargent EH, Yang X. Efficient Tandem Quantum-Dot LEDs Enabled by An Inorganic Semiconductor-Metal-Dielectric Interconnecting Layer Stack. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2108150. [PMID: 34761462 DOI: 10.1002/adma.202108150] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Indexed: 06/13/2023]
Abstract
Light-emitting diodes (LEDs) in a tandem configuration offer a strategy to realize high-performance, multicolor devices. Until now, though, the efficiency of tandem colloidal quantum dot LEDs (QLEDs) has been limited due to unpassivated interfaces and solvent damage originating from the materials processing requirements of interconnecting layers (ICLs). Here an ICL is reported consisting of a semiconductor-metal-dielectric stack that provides facile fabrication, materials stability, and good optoelectronic coupling. It is investigated experimentally how the ICL enables charge balance, suppresses current leakage, and prevents solvent damage to the underlying layers. As a result record efficiencies are reported for double-junction tandem QLEDs, whose emission wavelengths cover from blue to red light; i.e., external quantum efficiencies (EQEs) of 40% (average 37+/-2%) for red, 49% (average 45+/-2%) for yellow, 50% (average 46+/-2%) for green, and 24% (average 21+/-2%) for blue are achieved.
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Affiliation(s)
- Qianqian Wu
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, 149 Yanchang Road, Shanghai, 200072, China
| | - Xiwen Gong
- Department of Electrical and Computer Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario, M5S 1A4, Canada
| | - Dewei Zhao
- Institute of Solar Energy Materials and Devices, College of Materials Science and Engineering, Sichuan University, No. 24 South Section 1, Yihuan Road, Chengdu, 610065, China
| | - Yong-Biao Zhao
- Department of Electrical and Computer Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario, M5S 1A4, Canada
| | - Fan Cao
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, 149 Yanchang Road, Shanghai, 200072, China
| | - Haoran Wang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, 149 Yanchang Road, Shanghai, 200072, China
| | - Sheng Wang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, 149 Yanchang Road, Shanghai, 200072, China
| | - Jianhua Zhang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, 149 Yanchang Road, Shanghai, 200072, China
| | - Rafael Quintero-Bermudez
- Department of Electrical and Computer Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario, M5S 1A4, Canada
| | - Edward H Sargent
- Department of Electrical and Computer Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario, M5S 1A4, Canada
| | - Xuyong Yang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, 149 Yanchang Road, Shanghai, 200072, China
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Lv S, Yang K, Zhu Y, Guo T, Li F. Solution-processed white light-emitting device with polymer/quantum-dot composite emission layers. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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11
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Wang F, Wang Z, Zhu X, Bai Y, Yang Y, Hu S, Liu Y, You B, Wang J, Li Y, Tan Z. Highly Efficient and Super Stable Full-Color Quantum Dots Light-Emitting Diodes with Solution-Processed All-Inorganic Charge Transport Layers. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2007363. [PMID: 33656799 DOI: 10.1002/smll.202007363] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/18/2021] [Indexed: 06/12/2023]
Abstract
High performance and super stable all-inorganic full-color quantum dot light-emitting diodes (QLEDs) are constructed by adopting solution-processed Mg-doped NiOx (Mg-NiOx ) nanoparticles as hole transport layer (HTL) and Al-doped ZnO (AZO) as electron transport layer (ETL). Mg-NiOx nanoparticles possess the advantages of low-temperature solution processability, intrinsic stability, and controllable electronic properties. UV-ozone (UVO) treatment is applied to the Mg-NiOx film to modulate its surface composition. By carefully controlling the UVO treating time, favorable energy levels can be achieved to minimize the energy barrier for hole injection. At the cathode side, Al-doping can reduce the conductivity of ZnO ETL and decrease the interface charge transfer, effectively, thus leading to more balanced charge injection and consequent high luminance and efficiency. The maximum luminance and EQE can reach as high as 38 444 cd m-2 and 5.09% for R-QLEDs, 177 825 cd m-2 and 10.1% for G-QLEDs, and 3103 cd m-2 and 2.19% for B-QLEDs. The luminance values are the highest ever reported for all-inorganic QLEDs. Furthermore, the all-inorganic devices show much better resistance to water and oxygen existing in air. The results show that the ion-doped NiOx and AZO nanoparticles would facilitate the design and development of highly efficient and super stable QLEDs.
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Affiliation(s)
- Fuzhi Wang
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, Beijing Key Laboratory of Energy Security and Clean Utilization, North China Electric Power University, Beijing, 102206, China
| | - Zhenye Wang
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, Beijing Key Laboratory of Energy Security and Clean Utilization, North China Electric Power University, Beijing, 102206, China
| | - Xiaodong Zhu
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, Beijing Key Laboratory of Energy Security and Clean Utilization, North China Electric Power University, Beijing, 102206, China
| | - Yiming Bai
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, Beijing Key Laboratory of Energy Security and Clean Utilization, North China Electric Power University, Beijing, 102206, China
| | - Yun Yang
- Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou, 325027, China
| | - Siqian Hu
- Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, Jianghan University, Wuhan, 430056, China
| | - Yuqing Liu
- Poly OptoElectronics Tech. Ltd, Jiangmen, Guangdong, 529020, China
| | - Baogui You
- Poly OptoElectronics Tech. Ltd, Jiangmen, Guangdong, 529020, China
| | - Jun Wang
- Institute of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing, 100876, China
| | - Yang Li
- Poly OptoElectronics Tech. Ltd, Jiangmen, Guangdong, 529020, 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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12
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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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Chen Q, Yan Y, Wu X, Lan S, Hu D, Fang Y, Lv D, Zhong J, Chen H, Guo T. High-Performance Quantum-Dot Light-Emitting Transistors Based on Vertical Organic Thin-Film Transistors. ACS APPLIED MATERIALS & INTERFACES 2019; 11:35888-35895. [PMID: 31544456 DOI: 10.1021/acsami.9b11198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this work, a novel vertical quantum-dot light-emitting transistor (VQLET) based on a vertical organic thin-film transistor is successfully fabricated. Benefiting from the new vertical architecture, the VQLET is able to afford an extremely high current density, which allows most of the organic thin film transistors (OTFT) even with low mobility (for instance, poly(3-hexylthiophene)) to drive a quantum-dot light-emitting diode (QLED), which was previously unavailable. Moreover, the hole injection barrier could be modulated by the additional gate electrode, which precisely optimizes the charge balance in the device, a critical issue in QLED, resulting in the precise control of current density and brightness of the VQLET. The VQLET shows a high performance with a maximum current efficiency of 37 cd/A. Furthermore, integrating OTFT and QLED into a single device, the VQLET features drastic advantages by realizing active matrix quantum-dot light-emitting diodes (AMQLEDs), which significantly reduces the number of transistors and frees the large area fraction occupied by transistors. Hence, these results indicate that the VQLET provides a new strategy for realizing a low-cost, solution-processed, high-performance OTFT-AMQLED for the flat panel display technology. Moreover, the novel design offers a unique method to exquisitely control the charge balance and maximize the efficiency the QLED.
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Affiliation(s)
- Qizhen Chen
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Yujie Yan
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Xiaomin Wu
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Shuqiong Lan
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Daobing Hu
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Yuan Fang
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Dongxu Lv
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Jianfeng Zhong
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Huipeng Chen
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Tailiang Guo
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
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14
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Li D, Bai J, Zhang T, Chang C, Jin X, Huang Z, Xu B, Li Q. Blue quantum dot light-emitting diodes with high luminance by improving the charge transfer balance. Chem Commun (Camb) 2019; 55:3501-3504. [PMID: 30838368 DOI: 10.1039/c9cc00230h] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The development of blue quantum dot light-emitting diodes (QLEDs) lags far behind that of the red and green ones, which hinders the practical commercialization of QLEDs. Balancing the charge transfer still remains a challenging task, because blue QD emitters have a deeper valence band (VB) that creates a great injection barrier impeding the hole transfer. Herein, we demonstrate that the charge transfer balance can be improved by using a tert-butyldimethylsilyl chloride-modified poly(p-phenylene benzobisoxazole) (TBS-PBO) blocking layer. The TBS-PBO acts well in blocking excess electron injection and preserving the emission efficiency of the QD emitter. Compared to the insulating blocking layers, TBS-PBO has good conductivity, thus keeping the current density at a high level. Our device delivers a notable luminance of 4635 cd m-2 at an external quantum efficiency (EQE) maximum of 17.4%. To the best of our knowledge, the luminance with EQE > 17% is the highest one to be reported for blue QLEDs.
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Affiliation(s)
- Dongyu Li
- School of Physics Science and Technology, Lingnan Normal University, Zhanjiang 524048, P. R. China.
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15
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Khan Q, Subramanian A, Yu G, Maaz K, Li D, Sagar RUR, Chen K, Lei W, Shabbir B, Zhang Y. Structure optimization of perovskite quantum dot light-emitting diodes. NANOSCALE 2019; 11:5021-5029. [PMID: 30839976 DOI: 10.1039/c8nr09864f] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Although all-inorganic perovskite light emitting diodes (PeLED) have satisfactory stability under an ambient atmosphere, producing devices with high performance is challenging. A device architecture with a reduced energy barrier between adjacent layers and optimized energy level alignment in the PeLED is critical to achieve high electroluminescence efficiency. In this study, we report the optimization of a CsPbBr3-based PeLED device structure with Li-doped TiO2 nanoparticles as the electron transport layer (ETL). Optimal Li doping balances charge carrier injection between the hole transport layer (HTL) and ETL, leading to superior performance in both devices. The turn-on voltages for devices with Li-doped TiO2 nanoparticles were significantly reduced from 7.7 V to 4.9 V and from 3 V to 2 V in the direct and inverted PeLED structures, respectively. The low turn-on voltage for green emission is one of the lowest values among the reported CsPbBr3-based PeLEDs. Further investigations show that the device with an inverted structure is superior to the device with a direct structure because the energy barrier for carrier injection was minimized. The inverted structure devices exhibited a current efficiency of 5.6 cd A-1 for the pristine TiO2 ETL, while it was 15.2 cd A-1 for the Li-doped TiO2 ETL, a factor of ∼2.7 enhancement at 5000 cd m-2.
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Affiliation(s)
- Qasim Khan
- Shenzhen Key Laboratory of Flexible Memory Materials and Devices, College of Electronic Science and Technology, Shenzhen University, Shenzhen 518000, China.
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16
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Lee YJ, Kim HH, Lee YJ, Kim JH, Choi HJ, Choi WK. Electron transport phenomena at the interface of Al electrode and heavily doped degenerate ZnO nanoparticles in quantum dot light emitting diode. NANOTECHNOLOGY 2019; 30:035207. [PMID: 30452390 DOI: 10.1088/1361-6528/aaed98] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
ZnO nanoparticles (NPs) of 4-5 nm, widely adopted as an electron transport layer (ETL) in quantum dot light emitting diodes (QD-LEDs), were synthesized using the solution-precipitation process. It is notable that synthesized ZnO NPs are highly degenerate intrinsic semiconductors and their donor concentration can be increased up to N D = 6.9 × 1021 cm-3 by annealing at 140 °C in air. An optical bandgap increase of as large as 0.16-0.33 eV by degeneracy is explained well by the Burstein-Moss shift. In order to investigate the influence of intrinsic defects of ZnO NP ETLs on the performance of QD-LED devices without a combined annealing temperature between ZnO NP ETLs and the emissive QD layer, pre-annealed ZnO NPs at 60 °C, 90 °C, 140 °C, and 180 °C were spin-coated on the annealed QD layer without further post-annealing. As the annealing temperature increases from 60 °C to 180 °C, the defect density related to oxygen vacancy (V O) in ZnO NPs is reduced from 34.4% to 17.8%, whereas the defect density of interstitial Zn (Zni) is increased. Increased Zni reduces the width (W) of the depletion region from 0.21 to 0.12 nm and lowers the Schottky barrier (ФB) between ZnO NPs and the Al electrode from 1.19 to 0.98 eV. We reveal for the first time that carrier conduction between ZnO NP ETLs and the Al electrode is largely affected by the concentration of Zni above the conduction band minimum, and effectively described by space charge limited current and trap charge limited current models.
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Affiliation(s)
- Yeon Ju Lee
- Center for Opto-Electronic Materials and Devices, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea. Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Republic of Korea
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17
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Kim HM, Cho S, Kim J, Shin H, Jang J. Li and Mg Co-Doped Zinc Oxide Electron Transporting Layer for Highly Efficient Quantum Dot Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2018; 10:24028-24036. [PMID: 29952540 DOI: 10.1021/acsami.8b04721] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Zinc-oxide (ZnO) is widely used as an n-type electron transporting layer (ETL) for quantum dot (QD) light-emitting diode (QLED) because various metal doping can be possible and ZnO nanoparticle can be processed at low temperatures. We report here a Li- and Mg-doped ZnO, MLZO, which is used for ETL of highly efficient and long lifetime QLEDs. Co-doping, Mg and Li, in ZnO increases its band gap and electrical resistivity and thus can enhance charge balance in emission layer (EML). It is found also that the O-H concentration at the oxide surface decreases and exciton decay time of QDs on the metal oxide increases by co-doping in ZnO. The inverted green QLEDs with MLZO ETL exhibits the maximum current efficiency (CEmax) of 69.1 cd/A, power efficiency (PEmax) of 73.8 lm/W, and external quantum efficiency (EQEmax) of 18.4%. This is at least two times higher compared with the efficiencies of the QLEDs with Mg-doped ZnO ETL. The optimum Li and Mg concentrations are found to be 10% each. The deep-red, red, light-blue, and deep-blue QLEDs with MLZO ETLs exhibit the CEmax of 6.0, 22.3, 1.9, and 0.5 cd/A, respectively. The MLZO introduced here can be widely used as ETL of highly efficient QLEDs.
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Affiliation(s)
- Hyo-Min Kim
- Advanced Display Research Center (ADRC), Department of Information Display , Kyung Hee University , Dongdaemoon-ku, Seoul 130-701 , Korea
| | - Sinyoung Cho
- Advanced Display Research Center (ADRC), Department of Information Display , Kyung Hee University , Dongdaemoon-ku, Seoul 130-701 , Korea
| | - Jeonggi Kim
- Advanced Display Research Center (ADRC), Department of Information Display , Kyung Hee University , Dongdaemoon-ku, Seoul 130-701 , Korea
| | - Hyeonjeong Shin
- Advanced Display Research Center (ADRC), Department of Information Display , Kyung Hee University , Dongdaemoon-ku, Seoul 130-701 , Korea
| | - Jin Jang
- Advanced Display Research Center (ADRC), Department of Information Display , Kyung Hee University , Dongdaemoon-ku, Seoul 130-701 , Korea
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18
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Jiang C, Zou J, Liu Y, Song C, He Z, Zhong Z, Wang J, Yip HL, Peng J, Cao Y. Fully Solution-Processed Tandem White Quantum-Dot Light-Emitting Diode with an External Quantum Efficiency Exceeding 25. ACS NANO 2018; 12:6040-6049. [PMID: 29894158 DOI: 10.1021/acsnano.8b02289] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Solution-processed electroluminescent tandem white quantum-dot light-emitting diodes (TWQLEDs) have the advantages of being low-cost and high-efficiency and having a wide color gamut combined with color filters, making this a promising backlight technology for high-resolution displays. However, TWQLEDs are rarely reported due to the challenge of designing device structures and the deterioration of film morphology with component layers that can be deposited from solutions. Here, we report an interconnecting layer with the optical, electrical, and mechanical properties required for fully solution-processed TWQLED. The optimized TWQLEDs exhibit a state-of-the-art current efficiency as high as 60.4 cd/A and an extremely high external quantum efficiency of 27.3% at a luminance of 100 000 cd/m2. A high color gamut of 124% NTSC 1931 standard can be achieved when combined with commercial color filters. These results represent the highest performance for solution-processed WQLEDs, unlocking the great application potential of TWQLEDs as backlights for new-generation displays.
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Affiliation(s)
- Congbiao Jiang
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Jianhua Zou
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
- Guangzhou New Vision Optoelectronic Technology Co., Ltd. , Guangzhou 510730 , China
| | - Yu Liu
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Chen Song
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Zhiwei He
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Zhenji Zhong
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Jian Wang
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Hin-Lap Yip
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Junbiao Peng
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Yong Cao
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
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Kim J, Kim HM, Jang J. Low Work Function 2.81 eV Rb 2CO 3-Doped Polyethylenimine Ethoxylated for Inverted Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2018; 10:18993-19001. [PMID: 29749230 DOI: 10.1021/acsami.8b04760] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
UNLABELLED We report a low work function (2.81 eV), Rb2CO3-doped polyethyleneimine ethoxylated (PEIE) which is used for highly efficient and long-lifetime, inverted organic light-emitting diodes (OLEDs). Doping Rb2CO3 into PEIE decreases the work function of Li-doped ZnO (LZO) by 1.0 eV and thus significantly improves electron injection ability into the emission layer (EML). The inverted OLED with PEIE:Rb2CO3 interfacial layer (IL) exhibits higher efficiency and longer operation lifetime than those of the device with a PEIE IL. It is found also that Mg-doped ZnO (MZO) can be used instead of LZO as electron transporting layer. MZO/PEIE Rb2CO3 shows a low work function of 2.81 eV. The OLED with MZO/PEIE:Rb2CO3 exhibits low operating voltage of 5.0 V at 1000 cd m-2 and low efficiency roll-off of 11.8% at high luminance of 10 000 cd m-2. The results are due to the suppressed exciton quenching at the MZO/organic EML interface.
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Affiliation(s)
- Jeonggi Kim
- Department of Information Display, Advanced Display Research Center (ADRC) , Kyung Hee University , Dongdaemoon-gu, Seoul 130-701 , Korea
| | - Hyo-Min Kim
- Department of Information Display, Advanced Display Research Center (ADRC) , Kyung Hee University , Dongdaemoon-gu, Seoul 130-701 , Korea
| | - Jin Jang
- Department of Information Display, Advanced Display Research Center (ADRC) , Kyung Hee University , Dongdaemoon-gu, Seoul 130-701 , Korea
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20
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Jin X, Chang C, Zhao W, Huang S, Gu X, Zhang Q, Li F, Zhang Y, Li Q. Balancing the Electron and Hole Transfer for Efficient Quantum Dot Light-Emitting Diodes by Employing a Versatile Organic Electron-Blocking Layer. ACS APPLIED MATERIALS & INTERFACES 2018; 10:15803-15811. [PMID: 29667818 DOI: 10.1021/acsami.8b00729] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The electron-blocking layer (EBL) is important to balance the charge carrier transfer and achieve highly efficient quantum dot light-emitting diodes (QLEDs). Here, we report the utilization of a soluble tert-butyldimethylsilyl chloride-modified poly( p-phenylene benzobisoxazole) (TBS-PBO) as an EBL for simultaneous good charge carrier transfer balance while maintaining a high current density. We show that the versatile TBS-PBO blocks excess electron injection into the quantum dots (QDs), thus leading to better charge carrier transfer balance. It also restricts the undesired QD-to-EBL electron-transfer process, which preserves the superior emission capabilities of the emitter. As a consequence, the TBS-PBO device delivers an external quantum efficiency (EQE) maximum of 16.7% along with a remarkable current density as high as 139 mA/cm2 with a brightness of 5484 cd/m2. The current density of our device is higher than those of insulator EBL-based devices because of the higher conductivity of the TBS-PBO versus insulator EBL, thus helping achieve high luminance values ranging from 1414 to 20 000 cd/cm2 with current densities ranging from 44 to 648 mA/cm2 and EQE > 14%. We believe that these unconventional features of the present TBS-PBO-based QLEDs will expand the wide use of TBS-PBO as buffer layers in other advanced QLED applications.
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Affiliation(s)
- Xiao Jin
- School of Physics Science and Technology , Lingnan Normal University , Zhanjiang 524048 , P. R. China
| | - Chun Chang
- Jiangxi Engineering Laboratory for Optoelectronics Testing Technology , Nanchang Hangkong University , Nanchang 330063 , P. R. China
| | - Weifeng Zhao
- School of Materials and Chemical Engineering , Xi'an Technological University , Xi'an 710021 , P. R. China
| | - Shujuan Huang
- School of Photovoltaic and Renewable Energy Engineering , University of New South Wales , Sydney , New South Wales 2052 , Australia
| | - Xiaobing Gu
- Jiangxi Engineering Laboratory for Optoelectronics Testing Technology , Nanchang Hangkong University , Nanchang 330063 , P. R. China
| | - Qin Zhang
- Jiangxi Engineering Laboratory for Optoelectronics Testing Technology , Nanchang Hangkong University , Nanchang 330063 , P. R. China
| | - Feng Li
- Jiangxi Engineering Laboratory for Optoelectronics Testing Technology , Nanchang Hangkong University , Nanchang 330063 , P. R. China
| | - Yubao Zhang
- Jiangxi Engineering Laboratory for Optoelectronics Testing Technology , Nanchang Hangkong University , Nanchang 330063 , P. R. China
| | - Qinghua Li
- School of Physics Science and Technology , Lingnan Normal University , Zhanjiang 524048 , P. R. China
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Kim HM, Kim J, Jang J. Quantum-dot light-emitting diodes with a perfluorinated ionomer-doped copper-nickel oxide hole transporting layer. NANOSCALE 2018; 10:7281-7290. [PMID: 29632918 DOI: 10.1039/c7nr09671b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Herein, we report all solution-processed green quantum-dot light-emitting diodes (G-QLEDs) by introducing a perfluorinated ionomer (PFI, Nafion 117) into quantum dots (QDs) to improve hole injection. To reduce the energy level mismatch between the hole transporting layer (HTL) and QDs and exciton quenching on the metal-oxide surface, a PFI-mixed copper-doped nickel oxide (Cu-NiO) HTL was introduced for G-QLEDs. Mixing Cu-NiO with a PFI increases the work function and induces phase separation between Cu-NiO and PFI; thus, energy band bending occurs on the surface such that effective hole injection can be possible. The phase-separated PFI molecules on HTL affect the thickness and compactness of G-QDs and make a smooth interface between G-QDs and HTL. The G-QLED with a PFI and Cu-NiO mixture HTL exhibits the maximum current efficiency (CEmax), power efficiency (PEmax), and external quantum efficiency (EQEmax) of 7.3 cd A-1, 2.1 lm W-1, and 2.14%, respectively, which are about 4 times those of the QLED with a Cu-NiO HTL.
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Affiliation(s)
- Hyo-Min Kim
- Department of Information Display and Advanced Display Research Center, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 02447, Korea.
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22
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Subramanian A, Pan Z, Zhang Z, Ahmad I, Chen J, Liu M, Cheng S, Xu Y, Wu J, Lei W, Khan Q, Zhang Y. Interfacial Energy-Level Alignment for High-Performance All-Inorganic Perovskite CsPbBr 3 Quantum Dot-Based Inverted Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2018; 10:13236-13243. [PMID: 29601175 DOI: 10.1021/acsami.8b01684] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
All-inorganic perovskite light-emitting diode (PeLED) has a high stability in ambient atmosphere, but it is a big challenge to achieve high performance of the device. Basically, device design, control of energy-level alignment, and reducing the energy barrier between adjacent layers in the architecture of PeLED are important factors to achieve high efficiency. In this study, we report a CsPbBr3-based PeLED with an inverted architecture using lithium-doped TiO2 nanoparticles as the electron transport layer (ETL). The optimal lithium doping balances the charge carrier injection between the hole transport layer and ETL, leading to superior device performance. The device exhibits a current efficiency of 3 cd A-1, a luminance efficiency of 2210 cd m-2, and a low turn-on voltage of 2.3 V. The turn-on voltage is one of the lowest values among reported CsPbBr3-based PeLEDs. A 7-fold increase in device efficiencies has been obtained for lithium-doped TiO2 compared to that for undoped TiO2-based devices.
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Affiliation(s)
- Alagesan Subramanian
- i-Lab , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou , Jiangsu 215123 , China
| | - Zhenghui Pan
- i-Lab , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou , Jiangsu 215123 , China
| | - Zhenbo Zhang
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering , Southeast University , Nanjing , Jiangsu 210096 , China
| | - Imtiaz Ahmad
- Department of Applied Chemistry , Xi'an Jiaotong-Liverpool University , Suzhou , Jiangsu 215123 , China
| | - Jing Chen
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering , Southeast University , Nanjing , Jiangsu 210096 , China
| | - Meinan Liu
- i-Lab , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou , Jiangsu 215123 , China
| | - Shuang Cheng
- i-Lab , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou , Jiangsu 215123 , China
| | - Yijun Xu
- i-Lab , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou , Jiangsu 215123 , China
| | - Jun Wu
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering , Southeast University , Nanjing , Jiangsu 210096 , China
| | - Wei Lei
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering , Southeast University , Nanjing , Jiangsu 210096 , China
| | - Qasim Khan
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering , Southeast University , Nanjing , Jiangsu 210096 , China
| | - Yuegang Zhang
- i-Lab , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou , Jiangsu 215123 , China
- Department of Physics , Tsinghua University , Beijing 100084 , China
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Zhang H, Chen S, Sun XW. Efficient Red/Green/Blue Tandem Quantum-Dot Light-Emitting Diodes with External Quantum Efficiency Exceeding 21. ACS NANO 2018; 12:697-704. [PMID: 29253334 DOI: 10.1021/acsnano.7b07867] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Highly efficient tandem quantum-dot light-emitting diodes (QLEDs) are developed by using an interconnecting layer (ICL) with the structure of ZnMgO/Al/HATCN/MoO3. The developed ICL exhibits high transparency, efficient charge generation/injection capability, and high robustness to resist solvent damage during deposition of the upper functional layers. With the proposed ICL, full color (red/green/blue, R/G/B) tandem QLEDs are demonstrated with extremely high current efficiency and external quantum efficiency (EQE): 17.9 cd/A and 21.4% for B-QLEDs, 121.5 cd/A and 27.6% for G-QLEDs, 41.5 cd/A and 23.1% for R-QLEDs. To the best of our knowledge, these are the highest values ever reported. In addition, the EQEs of R-, G-, and B-QLEDs all exceed 21%. The high efficiency can be well maintained over a wide range of luminance from 102 to 104 cd/m2. For example, even at a high brightness of 20 000 cd/m2, the EQE of R-, G-, and B-QLEDs can still sustain its 96%, 99%, and 78% maximum value, respectively. The demonstrated full-color tandem QLEDs, with extremely high efficiency, long operational lifetime, low roll-off efficiency, and high color purity, would be ideal candidates to bring QLEDs into the next generation of full-color displays and the solid-state lighting market.
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Affiliation(s)
- Heng Zhang
- 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
| | - Xiao Wei Sun
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology , Shenzhen, 518055, People's Republic of China
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Wang L, Lin J, Hu Y, Guo X, Lv Y, Tang Z, Zhao J, Fan Y, Zhang N, Wang Y, Liu X. Blue Quantum Dot Light-Emitting Diodes with High Electroluminescent Efficiency. ACS APPLIED MATERIALS & INTERFACES 2017; 9:38755-38760. [PMID: 29039645 DOI: 10.1021/acsami.7b10785] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
High-efficiency blue CdSe/ZnS quantum dots (QDs) have been synthesized for display application with emission peak over 460 nm with the purpose of reducing the harmful effect of short-wavelength light to human eyes. To reach a better charge balance, different size ZnO nanoparticles (NPs) were synthesized and electrical properties of ZnO NPs were analyzed. Quantum dot light-emitting diodes (QLEDs) based on as-prepared blue QDs and optimized ZnO NPs have been successfully fabricated. Using small-size ZnO NPs, we have obtained a maximum current efficiency (CE) of 14.1 cd A-1 and a maximum external quantum efficiency (EQE) of 19.8% for QLEDs with an electroluminescence (EL) peak at 468 nm. To the best of our knowledge, this EQE is the highest value in comparison to the previous reports. The CIE 1931 color coordinates (0.136, 0.078) of this device are quite close to the standard (0.14, 0.08) of National Television System Committee (NTSC) 1953. The color saturation blue QLEDs show great promise for use in next-generation full-color displays.
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Affiliation(s)
- Lishuang Wang
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences , Changchun, 130033 Jilin, China
- University of Chinese Academy of Sciences , Beijing 100049, China
| | - Jie Lin
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences , Changchun, 130033 Jilin, China
| | - Yongsheng Hu
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences , Changchun, 130033 Jilin, China
| | - Xiaoyang Guo
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences , Changchun, 130033 Jilin, China
| | - Ying Lv
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences , Changchun, 130033 Jilin, China
| | - Zhaobing Tang
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences , Changchun, 130033 Jilin, China
- University of Chinese Academy of Sciences , Beijing 100049, China
| | - Jialong Zhao
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University , Siping, 136000 Jilin, China
| | - Yi Fan
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences , Changchun, 130033 Jilin, China
| | - Nan Zhang
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences , Changchun, 130033 Jilin, China
| | - Yunjun Wang
- Suzhou Xingshuo Nanotech Co., Ltd. (Mesolight) , Suzhou, 215123 Jiangsu, China
| | - Xingyuan Liu
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences , Changchun, 130033 Jilin, China
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Kim HM, Kim J, Cho SY, Jang J. Solution-Processed Metal-Oxide p-n Charge Generation Junction for High-Performance Inverted Quantum-Dot Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2017; 9:38678-38686. [PMID: 29043766 DOI: 10.1021/acsami.7b14584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report solution-processed metal-oxide p-n junction, Li-doped CuO (Li:CuO) and Li-doped ZnO (Li:ZnO), as a charge generation junction (CGJ) in quantum-dot light-emitting diode (QLED) at reverse bias. Efficient charge generation is demonstrated in a stack of air-annealed Li:CuO and Li:ZnO layers in QLEDs. Air annealing of Li:ZnO on Li:CuO turns out to be a key process to decrease oxygen vacancy (Vo) and increase the copper (II) oxide (CuO) fraction at the Li:CuO/Li:ZnO interface for efficient charge generation. Green QLEDs incorporating Li:CuO/Li:ZnO CGJ show the maximum current and power efficiencies of 35.4 cd/A and 33.5 lm/W, respectively.
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Affiliation(s)
- Hyo-Min Kim
- Advanced Display Research Center (ADRC), Department of Information Display, Kyung Hee University , Dongdaemoon-ku, Seoul 130-701, Korea
| | - Jeonggi Kim
- Advanced Display Research Center (ADRC), Department of Information Display, Kyung Hee University , Dongdaemoon-ku, Seoul 130-701, Korea
| | - Sin-Young Cho
- Advanced Display Research Center (ADRC), Department of Information Display, Kyung Hee University , Dongdaemoon-ku, Seoul 130-701, Korea
| | - Jin Jang
- Advanced Display Research Center (ADRC), Department of Information Display, Kyung Hee University , Dongdaemoon-ku, Seoul 130-701, Korea
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Kim HM, Hwang E, Kim J, Jang J. 13-4: Invited Paper
: Charge Generation Junction for Quantum-dot Light Emitting Diodes. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/sdtp.11609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Hyo-Min Kim
- Advanced Display Research Center (ADRC) and Department of Information Display; Kyung Hee University; Seoul 130-701 Korea
| | - Eunsa Hwang
- Advanced Display Research Center (ADRC) and Department of Information Display; Kyung Hee University; Seoul 130-701 Korea
| | - Jeonggi Kim
- Advanced Display Research Center (ADRC) and Department of Information Display; Kyung Hee University; Seoul 130-701 Korea
| | - Jin Jang
- Advanced Display Research Center (ADRC) and Department of Information Display; Kyung Hee University; Seoul 130-701 Korea
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Wang L, Lv Y, Lin J, Fan Y, Zhao J, Wang Y, Liu X. High-efficiency inverted quantum dot light-emitting diodes with enhanced hole injection. NANOSCALE 2017; 9:6748-6754. [PMID: 28485442 DOI: 10.1039/c7nr01414g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Hybrid MoO3/HAT-CN is employed as a hole injection layer (HIL) in green inverted colloidal quantum dot light-emitting devices (QLEDs). The hybrid HILs can be easily prepared and have been found to effectively improve the electroluminescent properties. The best performance device had an HIL of 1.5 nm-thick MoO3/2.5 nm-thick HAT-CN and showed a turn-on voltage of 1.9 V, a maximum current efficiency (CEmax) of 41.3 cd A-1, and maximum external quantum efficiency of 9.72%. Compared to the corresponding devices with the single MoO3 or HAT-CN interlayer, the CEmax of the hole-only devices was improved by 1.6 or 1.5 times, respectively. The measured electrical performance shows that hole-only devices with hybrid HILs have a smaller leakage current density at low driving voltage and much enhanced hole injection current than the devices with single interlayers. It indicates that much improved electroluminescent efficiency in green inverted QLEDs with hybrid MoO3/HAT-CN orginates from the significant enhancement of hole injection efficiency and suppression of space charge accumulation in the quantum dot-emitting region due to the improved balance of the charge carriers. The hybrid HILs can be extended to other color inverted QLEDs, which are favorable to achieve bright, highly efficient, and color saturation devices for display applications.
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Affiliation(s)
- Lishuang Wang
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
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Shang Y, Ning Z. Colloidal quantum-dots surface and device structure engineering for high-performance light-emitting diodes. Natl Sci Rev 2017. [DOI: 10.1093/nsr/nww097] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
The application of colloidal quantum dots for light-emitting devices has attracted considerable attention in recent years, due to their unique optical properties such as size-dependent emission wavelength, sharp emission peak and high luminescent quantum yield. Tremendous efforts have been made to explore quantum dots for light-emission applications such as light-emitting diodes (LEDs) and light converters. The performance of quantum-dots-based light-emitting diodes (QD-LEDs) has been increasing rapidly in recent decades as the development of quantum-dots synthesis, surface-ligand engineering and device-architecture optimization. Recently, the external quantum efficiencies of red quantum-dots LEDs have exceeded 20.5% with good stability and narrow emission peak. In this review, we summarize the recent advances in QD-LEDs, focusing on quantum-dot surface engineering and device-architecture optimization.
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Affiliation(s)
- Yuequn Shang
- School of Physical Science and Technology, Shanghai Tech University, Shanghai 201210, China
- Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhijun Ning
- School of Physical Science and Technology, Shanghai Tech University, Shanghai 201210, China
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Mahato S. Composition analysis of two different PEDOT:PSS commercial products used as an interface layer in Au/n-Si Schottky diode. RSC Adv 2017. [DOI: 10.1039/c7ra10018c] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The water based highly conductive transparent poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) polymer is a promising material for many optoelectronic device applications.
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Affiliation(s)
- Somnath Mahato
- Saha Institute of Nuclear Physics (Surface Physics and Material Science)
- Kolkata 700064
- India
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30
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Song DH, Song SH, Shen TZ, Lee JS, Park WH, Kim SS, Song JK. Quantum dot light-emitting diodes using a graphene oxide/PEDOT:PSS bilayer as hole injection layer. RSC Adv 2017. [DOI: 10.1039/c7ra07948f] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Adoption of graphene oxide/PEDOT:PSS as a HIL layer dramatically improves the electro-optical performance of QLED devices.
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Affiliation(s)
- Dae-Ho Song
- School of Electronic and Electrical Engineering
- Sungkyunkwan University
- Suwon 440-746
- South Korea
- Display Laboratory
| | - Suk-Ho Song
- School of Electronic and Electrical Engineering
- Sungkyunkwan University
- Suwon 440-746
- South Korea
| | - Tian-Zi Shen
- School of Electronic and Electrical Engineering
- Sungkyunkwan University
- Suwon 440-746
- South Korea
| | - Jun-Seo Lee
- School of Electronic and Electrical Engineering
- Sungkyunkwan University
- Suwon 440-746
- South Korea
| | - Won-Hyeok Park
- School of Electronic and Electrical Engineering
- Sungkyunkwan University
- Suwon 440-746
- South Korea
| | - Sang-Soo Kim
- School of Electronic and Electrical Engineering
- Sungkyunkwan University
- Suwon 440-746
- South Korea
| | - Jang-Kun Song
- School of Electronic and Electrical Engineering
- Sungkyunkwan University
- Suwon 440-746
- South Korea
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Kim HM, Geng D, Kim J, Hwang E, Jang J. Metal-Oxide Stacked Electron Transport Layer for Highly Efficient Inverted Quantum-Dot Light Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2016; 8:28727-28736. [PMID: 27696804 DOI: 10.1021/acsami.6b10314] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report highly efficient inverted quantum-dot light emitting diodes (QLEDs) using an Al doped ZnO (AZO)/Li doped ZnO (LZO) stack electron transport layer (ETL). An introduction of the LZO layer on AZO improved the current and power efficiencies of the green (G-) QLEDs from 10.5 to 34.0 cd A-1 and from 5.4 to 29.6 lm W-1, respectively. The red (R-), G-, and blue (B-) QLEDs fabricated in this work exhibited the maximum external quantum efficiencies (EQEs) of 8.4, 12.5, and 4.3%, respectively. It is found from time-resolved photoluminescence (PL) and transient electroluminescence (EL) decay that exciton loss at the interface between the ETL and the emission layer can be significantly reduced by introducing LZO.
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Affiliation(s)
- Hyo-Min Kim
- Advanced Display Research Center (ADRC), Department of Information Display, Kyung Hee University , Dongdaemoon-ku, Seoul 130-701, Korea
| | - Di Geng
- Advanced Display Research Center (ADRC), Department of Information Display, Kyung Hee University , Dongdaemoon-ku, Seoul 130-701, Korea
| | - Jeonggi Kim
- Advanced Display Research Center (ADRC), Department of Information Display, Kyung Hee University , Dongdaemoon-ku, Seoul 130-701, Korea
| | - Eunsa Hwang
- Advanced Display Research Center (ADRC), Department of Information Display, Kyung Hee University , Dongdaemoon-ku, Seoul 130-701, Korea
| | - Jin Jang
- Advanced Display Research Center (ADRC), Department of Information Display, Kyung Hee University , Dongdaemoon-ku, Seoul 130-701, Korea
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Liu G, Zhou X, Chen S. Very Bright and Efficient Microcavity Top-Emitting Quantum Dot Light-Emitting Diodes with Ag Electrodes. ACS APPLIED MATERIALS & INTERFACES 2016; 8:16768-16775. [PMID: 27299501 DOI: 10.1021/acsami.6b03367] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The microcavity effect in top-emitting quantum dot light-emitting diodes (TQLEDs) is theoretically and experimentally investigated. By carefully optimizing the cavity length, the thickness of the top Ag electrode and the thickness of the capping layer, very bright and efficient TQLEDs with external quantum efficiency (EQE) of 12.5% are demonstrated. Strong dependence of luminance and efficiency on cavity length is observed, in good agreement with theoretical calculation. By setting the normal-direction resonant wavelength around the peak wavelength of the intrinsic emission, highest luminance of 112 000 cd/m(2) (at a driving voltage of 7 V) and maximum current efficiency of 27.8 cd/A are achieved, representing a 12-fold and a 2.1-fold enhancement compared to 9000 cd/m(2) and 13.2 cd/A of the conventional bottom emitting devices, respectively, whereas the highest EQE of 12.5% is obtained by setting the resonant wavelength 30 nm longer than the peak wavelength of the intrinsic emission. Benefit from the very narrow spectrum of QDs and the low absorption of silver electrodes, the potential of microcavity effect can be fully exploited in TQLEDs.
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Affiliation(s)
- Guohong Liu
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology , Shenzhen 518055, P. R. China
- State Key Lab of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-sen University , Guangzhou 510275, P. R. China
| | - Xiang Zhou
- State Key Lab of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-sen University , Guangzhou 510275, 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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Kim HM, Lee J, Hwang E, Kim J, Jang J. P-95: Inverted Tandem Architecture of Quantum-dot Light Emitting Diodes with Solution Processed Charge Generation Layers. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/sdtp.10952] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Hyo-Min Kim
- Advanced Display Research Center (ADRC) and Department of Information Display Kyung Hee University, Seoul 130-701, Korea
| | - Jieun Lee
- Advanced Display Research Center (ADRC) and Department of Information Display Kyung Hee University, Seoul 130-701, Korea
| | - Eunsa Hwang
- Advanced Display Research Center (ADRC) and Department of Information Display Kyung Hee University, Seoul 130-701, Korea
| | - Jeonggi Kim
- Advanced Display Research Center (ADRC) and Department of Information Display Kyung Hee University, Seoul 130-701, Korea
| | - Jin Jang
- Advanced Display Research Center (ADRC) and Department of Information Display Kyung Hee University, Seoul 130-701, Korea
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Jia Y, Wang H, Yan Z, Deng L, Dong H, Ma N, Sun D. A facile method for the synthesis of CuInS2–ZnS quantum dots with tunable photoluminescent properties. RSC Adv 2016. [DOI: 10.1039/c6ra14733j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
CuInS2/CuInS2–ZnS quantum dots showed excellent tunable photoluminescent properties, which demonstrate great potential for practical applications due to their non-toxicity and excellent optical properties.
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Affiliation(s)
- Yihe Jia
- National Center for Materials Service Safety
- University of Science and Technology Beijing
- Beijing 100083
- China
| | - Haicheng Wang
- National Center for Materials Service Safety
- University of Science and Technology Beijing
- Beijing 100083
- China
| | - Zhiran Yan
- National Center for Materials Service Safety
- University of Science and Technology Beijing
- Beijing 100083
- China
| | - Ling Deng
- National Center for Materials Service Safety
- University of Science and Technology Beijing
- Beijing 100083
- China
| | - Hua Dong
- National Center for Materials Service Safety
- University of Science and Technology Beijing
- Beijing 100083
- China
| | - Ning Ma
- College of Materials Science and Chemical Engineering
- Harbin Engineering University
- Harbin 150001
- China
| | - Dongbai Sun
- National Center for Materials Service Safety
- University of Science and Technology Beijing
- Beijing 100083
- China
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Bonsu RO, Bock DC, Kim H, Korotkov RY, Abboud KA, Anderson TJ, McElwee-White L. Synthesis and evaluation of κ2-β-diketonate and β-ketoesterate tungsten(vi) oxo-alkoxide complexes as precursors for chemical vapor deposition of WOx thin films. Dalton Trans 2016; 45:10897-908. [DOI: 10.1039/c6dt01078d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
β-Diketonate and β-ketoesterate tungsten(vi) oxo-alkoxide complexes were synthesized and CVD of WOx from WO(OCH2C(CH3)3)3(tbac) was demonstrated.
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Affiliation(s)
- Richard O. Bonsu
- Department of Chemistry
- University of Florida
- Gainesville
- 32611-7200 USA
| | - Duane C. Bock
- Department of Chemistry
- University of Florida
- Gainesville
- 32611-7200 USA
| | - Hankook Kim
- Department of Chemical Engineering
- University of Florida
- Gainesville
- 32611-6005 USA
| | | | - Khalil A. Abboud
- Department of Chemistry
- University of Florida
- Gainesville
- 32611-7200 USA
| | - Timothy J. Anderson
- Department of Chemical Engineering
- University of Florida
- Gainesville
- 32611-6005 USA
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