1
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Xu M, Zhao C, Meng Z, Yan H, Chen H, Jiang Z, Jiang Z, Chen H, Meng L, Hui W, Su Z, Wang Y, Wang Z, Wang J, Gao Y, He Y, Meng H. Nonvolatile Memory Organic Light-Emitting Transistors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2307703. [PMID: 37812077 DOI: 10.1002/adma.202307703] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 09/28/2023] [Indexed: 10/10/2023]
Abstract
In the field of active-matrix organic light emitting display (AMOLED), large-size and ultra-high-definition AMOLED applications have escalated the demand for the integration density of driver chips. However, as Moore's Law approaches the limit, the traditional technology of improving integration density that relies on scaling down device dimension is facing a huge challenge. Thus, developing a multifunctional and highly integrated device is a promising route for improving the integration density of pixel circuits. Here, a novel nonvolatile memory ferroelectric organic light-emitting transistor (Fe-OLET) device which integrates the switching capability, light-emitting capability and nonvolatile memory function into a single device is reported. The nonvolatile memory function of Fe-OLET is achieved through the remnant polarization property of ferroelectric polymer, enabling the device to maintain light emission at zero gate bias. The reliable nonvolatile memory operations are also demonstrated. The proof-of-concept device optimized through interfacial modification approach exhibits 20 times improved field-effect mobility and five times increased luminance. The integration of nonvolatile memory, switching and light-emitting capabilities within Fe-OLET provides a promising internal-storage-driving paradigm, thus creating a new pathway for deploying storage capacitor-free circuitry to improve the pixel aperture ratio and the integration density of circuits toward the on-chip advanced display applications.
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Affiliation(s)
- Meili Xu
- School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
| | - Changbin Zhao
- School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
| | - Zhimin Meng
- School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
| | - Hao Yan
- School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
| | - Hongming Chen
- College of Materials Science and Engineering, Fuzhou University, Fuzhou, 350116, China
| | - Zhixiang Jiang
- Institute of Flexible Electronics, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Zhuonan Jiang
- School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
| | - Hong Chen
- School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
| | - Lingqiang Meng
- School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
| | - Wei Hui
- Institute of Flexible Electronics, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Zhenhuang Su
- Shanghai Synchrotron Radiation Facility, Zhangjiang Lab, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201204, China
| | - Yueyue Wang
- School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
| | - Zhenhui Wang
- School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
| | - Jianing Wang
- Institute of Flexible Electronics, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Yuanhong Gao
- School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
| | - Yaowu He
- School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
| | - Hong Meng
- School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
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2
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Chiu SW, Hsu A, Ying L, Liaw YK, Lin KT, Ruan J, Samuel IDW, Hsu BBY. Achieving Bright Organic Light-Emitting Field-Effect Transistors with Sustained Efficiency through Hybrid Contact Design. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37310808 DOI: 10.1021/acsami.3c01842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Organic light-emitting field-effect transistors (OLEFETs) with bilayer structures have been widely studied due to their potential to integrate high-mobility organic transistors and efficient organic light-emitting diodes. However, these devices face a major challenge of imbalance charge transport, leading to a severe efficiency roll-off at high brightness. Here, we propose a solution to this challenge by introducing a transparent organic/inorganic hybrid contact with specially designed electronic structures. Our design aims to steadily accumulate the electrons injected into the emissive polymer, allowing the light-emitting interface to effectively capture more holes even when the hole current increases. Our numerical simulations show that the capture efficiency of these steady electrons will dominate charge recombination and lead to a sustained external quantum efficiency of 0.23% over 3 orders of magnitude of brightness (4 to 7700 cd/m2) and current density (1.2 to 2700 mA/cm2) from -4 to -100 V. The same enhancement is retained even after increasing the external quantum efficiency (EQE) to 0.51%. The high and tunable brightness with stable efficiency offered by hybrid-contact OLEFETs makes them ideal light-emitting devices for various applications. These devices have the potential to revolutionize the field of organic electronics by overcoming the fundamental challenge of imbalance charge transport.
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Affiliation(s)
- Shih-Wei Chiu
- Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan
| | - An Hsu
- Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan
| | - Lei Ying
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, P. R. China
| | - Yong-Kang Liaw
- Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan
| | - Kun-Ta Lin
- Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan
| | - Jrjeng Ruan
- Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, U.K
| | - Ben B Y Hsu
- Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan
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3
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Gao C, Shukla A, Gao H, Miao Z, Zhang Y, Wang P, Luo G, Zeng Y, Wong WWH, Smith TA, Lo SC, Hu W, Namdas EB, Dong H. Harvesting Triplet Excitons in High Mobility Emissive Organic Semiconductor for Efficiency Enhancement of Light-Emitting Transistors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208389. [PMID: 36639351 DOI: 10.1002/adma.202208389] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 01/01/2023] [Indexed: 06/17/2023]
Abstract
Organic light-emitting transistors (OLETs), a kind of highly integrated and minimized optoelectronic device, demonstrate great potential applications in various fields. The construction of high-performance OLETs requires the integration of high charge carrier mobility, strong emission, and high triplet exciton utilization efficiency in the active layer. However, it remains a significant long-term challenge, especially for single component active layer OLETs. Herein, the successful harvesting of triplet excitons in a high mobility emissive molecule, 2,6-diphenylanthracene (DPA), through the triplet-triplet annihilation process is demonstrated. By incorporating a highly emissive guest into the DPA host system, an obvious increase in photoluminescence efficiency along with exciton utilization efficiency results in an obvious enhancement of external quantum efficiency of 7.2 times for OLETs compared to the non-doped devices. Moreover, well-tunable multi-color electroluminescence, especially white emission with Commission Internationale del'Eclairage of (0.31, 0.35), from OLETs is also achieved by modulating the doping concentration with a controlled energy transfer process. This work opens a new avenue for integrating strong emission and efficient exciton utilization in high-mobility organic semiconductors for high-performance OLETs and advancing their related functional device applications.
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Affiliation(s)
- Can Gao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Atul Shukla
- Centre for Organic Photonics & Electronics, School of Mathematics and Physics, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Haikuo Gao
- Shandong Engineering Research Center of Aeronautical Materials and Devices, College of Aeronautical Engineering, Binzhou University, Binzhou, 251900, China
| | - Zhagen Miao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yihan Zhang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Pu Wang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Guiwen Luo
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yi Zeng
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Wallace W H Wong
- ARC Centre of Excellence in Exciton Science, School of Chemistry, Bio21 Institute, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Trevor A Smith
- ARC Centre of Excellence in Exciton Science, School of Chemistry, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Shih-Chun Lo
- Centre for Organic Photonics and Electronics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Wenping Hu
- Tianjin Key Laboratory of Molecular Optoelectronic Science, Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
| | - Ebinazar B Namdas
- Centre for Organic Photonics & Electronics, School of Mathematics and Physics, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Huanli Dong
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
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4
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Cao HT, Hou PF, Yu WJ, Gao Y, Li B, Feng QY, Zhang H, Wang SS, Su ZM, Xie LH. Enhanced Efficiency of Exciplex Emission from a 9-Phenylfluorene Derivative. ACS APPLIED MATERIALS & INTERFACES 2023; 15:7236-7246. [PMID: 36700822 DOI: 10.1021/acsami.2c22266] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The exciplex-thermally activated delayed fluorescence (exciplex-TADF) system is an excellent candidate for the fabrication of high-efficiency organic light-emitting diodes (OLEDs) because of its more easily achieved small singlet-triplet energy splitting (ΔEST) and doping control. However, exciplex-TADF is still faced with the problems of low external quantum efficiency (ηext) and unclear effect of structure modification in electron acceptors. Herein, we provide a steric hindrance increase strategy to obtain high-efficiency exciplex emissions. Through introducing a 9-phenylfluorene group into N-ethylcarbazole of the dicyano-substituted 9-phenylfluorene, an electron acceptor material with increased steric hindrance is obtained, which helps the exciplex harvest a larger driving force and higher emission efficiencies. Encouragingly, the obtained OLED displays a maximum ηext of 25.8%, which is one of the best efficiency values among reported exciplex-OLEDs, simultaneously possessing excellent current efficiency of 83.6 cd A-1 and power efficiency of 93.7 lm W-1. It is expected that this work will offer a new avenue for designing electron acceptors for highly efficient exciplex emissions.
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Affiliation(s)
- Hong-Tao Cao
- Center for Molecular Systems and Organic Devices (CMSOD), State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, P.R. China
| | - Peng-Fei Hou
- Center for Molecular Systems and Organic Devices (CMSOD), State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, P.R. China
| | - Wen-Jing Yu
- Center for Molecular Systems and Organic Devices (CMSOD), State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, P.R. China
| | - Ying Gao
- Institute of Biomass Functional Materials Interdisciplinary Studies, Jilin Engineering Normal University, 3050 Kaixuan Road, Changchun 130052, P.R. China
| | - Bo Li
- Center for Molecular Systems and Organic Devices (CMSOD), State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, P.R. China
| | - Quan-You Feng
- Center for Molecular Systems and Organic Devices (CMSOD), State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, P.R. China
| | - He Zhang
- Center for Molecular Systems and Organic Devices (CMSOD), State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, P.R. China
| | - Sha-Sha Wang
- Center for Molecular Systems and Organic Devices (CMSOD), State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, P.R. China
| | - Zhong-Min Su
- College of Chemistry, Northeast Normal University, 5268 Renmin Street, Changchun 130024, P.R. China
| | - Ling-Hai Xie
- Center for Molecular Systems and Organic Devices (CMSOD), State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, P.R. China
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5
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Huang J, Hung H, Hsu K, Chen C, Lee P, Lin H, Lin B, Leung M, Chiu T, Lee J, Friend RH, Wu Y. Numerical Analysis and Optimization of a Hybrid Layer Structure for Triplet–Triplet Fusion Mechanism in Organic Light‐Emitting Diodes. ADVANCED THEORY AND SIMULATIONS 2022. [DOI: 10.1002/adts.202200633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Jun‐Yu Huang
- Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering National Taiwan University Taipei 10617 Taiwan
- Cavendish Laboratory University of Cambridge Cambridge CB3 0HE UK
| | - Hsiao‐Chun Hung
- Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering National Taiwan University Taipei 10617 Taiwan
| | - Kung‐Chi Hsu
- Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering National Taiwan University Taipei 10617 Taiwan
| | - Chia‐Hsun Chen
- Department of Chemistry National Taiwan University Taipei 10617 Taiwan
| | - Pei‐Hsi Lee
- Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering National Taiwan University Taipei 10617 Taiwan
| | - Hung‐Yi Lin
- Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering National Taiwan University Taipei 10617 Taiwan
| | - Bo‐Yen Lin
- Department of Opto‐Electronic Engineering National Dong Hwa University Shoufeng Hualien 974301 Taiwan
| | - Man‐kit Leung
- Department of Chemistry National Taiwan University Taipei 10617 Taiwan
| | - Tien‐Lung Chiu
- Department of Electrical Engineering Yuan‐Ze University Taoyuan 32003 Taiwan
| | - Jiun‐Haw Lee
- Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering National Taiwan University Taipei 10617 Taiwan
| | | | - Yuh‐Renn Wu
- Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering National Taiwan University Taipei 10617 Taiwan
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6
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Du Y, Yuan D, Awais MA, Yu L. New semi-ladder polymers for ambipolar organic light-emitting transistors. Chem Commun (Camb) 2022; 58:11347-11353. [PMID: 36134950 DOI: 10.1039/d2cc04087e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Organic light-emitting transistors (OLETs) combine the light-emitting and gate-modulated electrical switching functions in a single device. Over the past two decades, progress has been made in developing new fluorescent semiconductors and device engineering to improve the properties of OLETs. In this paper, we give a brief review of the achievement and disadvantages of the present polymer-based OLETs, while highlighting the recent developments in semi-ladder polymers from our lab for new electroluminescent materials. The special folded molecular structures and unique aggregation states make these polymers suitable for exploration as OLET materials. A short conclusion is provided with a discussion on the challenges and future perspectives in this field.
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Affiliation(s)
- Yachu Du
- Department of Chemistry and James Franck Institute, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, USA.
| | - Dafei Yuan
- College of Materials Science and Engineering, Hunan University, Changsha, Hunan, 410082, China
| | - Mohammad A Awais
- Department of Chemistry and James Franck Institute, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, USA.
| | - Luping Yu
- Department of Chemistry and James Franck Institute, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, USA.
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7
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Gao C, Wong WWH, Qin Z, Lo SC, Namdas EB, Dong H, Hu W. Application of Triplet-Triplet Annihilation Upconversion in Organic Optoelectronic Devices: Advances and Perspectives. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2100704. [PMID: 34596295 DOI: 10.1002/adma.202100704] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 08/06/2021] [Indexed: 06/13/2023]
Abstract
Organic semiconductor materials have been widely used in various optoelectronic devices due to their rich optical and/or electrical properties, which are highly related to their excited states. Therefore, how to manage and utilize the excited states in organic semiconductors is essential for the realization of high-performance optoelectronic devices. Triplet-triplet annihilation (TTA) upconversion is a unique process of converting two non-emissive triplet excitons to one singlet exciton with higher energy. Efficient optical-to-electrical devices can be realized by harvesting sub-bandgap photons through TTA-based upconversion. In electrical-to-optical devices, triplets generated after the combination of electrons and holes also can be efficiently utilized via TTA, which resulted in a high internal conversion efficiency of 62.5%. Currently, many interesting explorations and significant advances have been demonstrated in these fields. In this review, a comprehensive summary of these intriguing advances on developing efficient TTA upconversion materials and their application in optoelectronic devices is systematically given along with some discussions. Finally, the key challenges and perspectives of TTA upconversion systems for further improvement for optoelectronic devices and other related research directions are provided. This review hopes to provide valuable guidelines for future related research and advancement in organic optoelectronics.
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Affiliation(s)
- Can Gao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Wallace W H Wong
- ARC Centre of Excellence in Exciton Science, School of Chemistry, Bio21 Institute, The University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Zhengsheng Qin
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shih-Chun Lo
- Centre for Organic Photonics and Electronics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Ebinazar B Namdas
- Centre for Organic Photonics & Electronics, School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Huanli Dong
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Wenping Hu
- Tianjin Key Laboratory of Molecular Optoelectronic Science, Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
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8
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Chen Y, Wang H, Yao Y, Wang Y, Ma C, Samorì P. Synaptic Plasticity Powering Long-Afterglow Organic Light-Emitting Transistors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2103369. [PMID: 34369012 DOI: 10.1002/adma.202103369] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 06/03/2021] [Indexed: 06/13/2023]
Abstract
Long-lasting luminescence in optoelectronic devices is highly sought after for applications in optical data storage and display technology. While in light-emitting diodes this is achieved by exploiting long-afterglow organic materials as active components, such a strategy has never been pursued in light-emitting transistors, which are still rather unexplored and whose technological potential is yet to be demonstrated. Herein, the fabrication of long-afterglow organic light-emitting transistors (LAOLETs) is reported whose operation relies on an unprecedented strategy based on a photoinduced synaptic effect in an inorganic indium-gallium-zinc-oxide (IGZO) semiconducting channel layer, to power a persistent electroluminescence in organic light-emitting materials. Oxygen vacancies in the IGZO layer, produced by irradiation at λ = 312 nm, free electrons in excess yielding to a channel conductance increase. Due to the slow recombination kinetics of photogenerated electrons to oxygen vacancies in the channel layer, the organic material can be fueled by postsynaptic current and displays a long-lived light-emission (hundreds of seconds) after ceasing UV irradiation. As a proof-of-concept, the LAOLETs are integrated in active-matrix light-emitting arrays operating as visual UV sensors capable of long-lifetime green-light emission in the irradiated regions.
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Affiliation(s)
- Yusheng Chen
- Université de Strasbourg, CNRS, ISIS, 8 allée Gaspard Monge, Strasbourg, 67000, France
| | - Hanlin Wang
- Université de Strasbourg, CNRS, ISIS, 8 allée Gaspard Monge, Strasbourg, 67000, France
| | - Yifan Yao
- Université de Strasbourg, CNRS, ISIS, 8 allée Gaspard Monge, Strasbourg, 67000, France
| | - Ye Wang
- Université de Strasbourg, CNRS, ISIS, 8 allée Gaspard Monge, Strasbourg, 67000, France
| | - Chun Ma
- Université de Strasbourg, CNRS, ISIS, 8 allée Gaspard Monge, Strasbourg, 67000, France
| | - Paolo Samorì
- Université de Strasbourg, CNRS, ISIS, 8 allée Gaspard Monge, Strasbourg, 67000, France
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9
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Qin Z, Gao H, Dong H, Hu W. Organic Light-Emitting Transistors Entering a New Development Stage. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2007149. [PMID: 34021637 DOI: 10.1002/adma.202007149] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 01/03/2021] [Indexed: 05/25/2023]
Abstract
Organic light-emitting transistors (OLETs) are possibly the smallest integrated optoelectronic devices that combine the switching and amplification mechanisms of organic field-effect transistors (OFETs) and the electroluminescent characteristic of organic light-emitting diodes (OLEDs). Such a unique architecture of OLETs makes them ideal for developing the next-generation display technology and electrically pumped lasers for miniaturized photonic devices and circuits. However, the development of OLETs has been slow. Recently, some exciting progress has been made with breakthroughs in high mobility emissive organic semiconductors, construction of high-performance OLETs, and fabrication of novel multifunctional OLETs. This recent slew of advances may represent the advent of a new development stage of OLETs and their related devices and circuits. In this paper, a detailed review of these fantastic advances is presented, with a special focus on the key points for developing high-performance OLETs. Finally, a brief conclusion is provided with a discussion on the challenges and future perspectives in this field.
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Affiliation(s)
- Zhengsheng Qin
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Haikuo Gao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Huanli Dong
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Wenping Hu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University and Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China
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10
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Chen H, Huang W, Marks TJ, Facchetti A, Meng H. Recent Advances in Multi-Layer Light-Emitting Heterostructure Transistors. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2007661. [PMID: 33660408 DOI: 10.1002/smll.202007661] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/21/2021] [Indexed: 06/12/2023]
Abstract
Light-emitting transistors (LETs) have attracted tremendous academic and industrial interest due to their dual functions of electrical switching and light emission in a single device, which can considerably reduce system complexity and manufacturing costs, especially in the area of flat panel and flexible displays as well as lighting and lasers. In recent years, enhanced LET performance has been achieved by introducing multiple-layer heterostructures in the charge-carrying/light-emitting LET channel versus the best-reported performance in single active layer LETs, rendering multi-layer LETs promising candidates for next-generation display technologies. In this review, the fundamental structures and working principles of multi-layer heterostructure LETs are introduced. Next, developments in multi-layer LETs are discussed based on co-planar LETs, non-planar LETs, and vertical LETs including organic, quantum dot, and perovskite light emitters. Finally, this review concludes with a summary and a perspective on the future of this research field.
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Affiliation(s)
- Hongming Chen
- School of Advanced Materials, Peking University Shenzhen Graduate School, 2199 Lishui Road, Shenzhen, 518055, P. R. China
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Wei Huang
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Tobin J Marks
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Antonio Facchetti
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
- Flexterra Corporation, 8025 Lamon Avenue, Skokie, IL, 60077, USA
| | - Hong Meng
- School of Advanced Materials, Peking University Shenzhen Graduate School, 2199 Lishui Road, Shenzhen, 518055, P. R. China
- School of Electronics and Information, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, 710072, P. R. China
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11
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Zhang M, Zheng CJ, Lin H, Tao SL. Thermally activated delayed fluorescence exciplex emitters for high-performance organic light-emitting diodes. MATERIALS HORIZONS 2021; 8:401-425. [PMID: 34821262 DOI: 10.1039/d0mh01245a] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Owing to their natural thermally activated delayed fluorescence (TADF) characteristics, the development of exciplex emitters for organic light-emitting diodes (OLEDs) has witnessed booming progress in recent years. Formed between electron-donating and electron-accepting molecules, exciplexes with intermolecular charge transfer processes have unique advantages compared with unimolecular TADF materials, offering a new way to develop high-performance TADF emitters. In this review, a comprehensive overview of TADF exciplex emitters is presented with a focus on the relationship between the constituents of exciplexes and their electroluminescence performance. We summarize and discuss the latest and most significant developments of TADF exciplex emitters. Notably, the design principles of efficient TADF exciplex emitters are systematically categorized into three systems within this review. These progressive achievements of TADF exciplex emitters point out future challenges to trigger more research endeavors in this growing field.
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Affiliation(s)
- Ming Zhang
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu, 610054, P. R. China.
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Hamada K, Tanaka R, Kamarudin MA, Shen Q, Iikubo S, Minemoto T, Yoshino K, Toyoda T, Ma T, Kang DW, Hayase S. Enhanced Device Performance with Passivation of the TiO 2 Surface Using a Carboxylic Acid Fullerene Monolayer for a SnPb Perovskite Solar Cell with a Normal Planar Structure. ACS APPLIED MATERIALS & INTERFACES 2020; 12:17776-17782. [PMID: 32204584 DOI: 10.1021/acsami.0c01411] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Research on tin-lead (SnPb) perovskite solar cells (PSCs) has gained popularity in recent years because of their low band gap, which could be applied to tandem solar cells. However, most of the work is based on inverted PSCs using PEDOT:PSS as the hole-transport layer as normal-structure PSCs show lower efficiency. In this work, the reason behind the low efficiency of normal-structure SnPb PSCs is elucidated and surface passivation has been tested as a method to overcome the problem. In the case of normal PSCs, at the interface between the titania layer and SnPb perovskite, there are many carrier traps observed originating from Ti-O-Sn bonds. In order to avoid the direct contact between titania and the SnPb perovskite layer, the titania surface is passivated with carboxylic acid C60 resulting in an efficiency increase from 5.14 to 7.91%. This will provide a direction of enhancing the efficiency of the normal-structure SnPb PSCs through heterojunction engineering.
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Affiliation(s)
- Kengo Hamada
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu-shi, Fukuoka-ken 808-0196, Japan
- Faculty of Informatics and Engineering, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
| | - Ryo Tanaka
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu-shi, Fukuoka-ken 808-0196, Japan
| | - Muhammad Akmal Kamarudin
- Faculty of Informatics and Engineering, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
| | - Qing Shen
- Faculty of Informatics and Engineering, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
| | - Satoshi Iikubo
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu-shi, Fukuoka-ken 808-0196, Japan
| | - Takashi Minemoto
- Department of Electrical and Electronic Engineering, Faculty of Science and Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| | - Kenji Yoshino
- Department of Electrical and Electronic Engineering, Miyazaki University, 1-1 Gakuen Kibanadai Nishi, Miyazaki 889-2192 Japan
| | - Taro Toyoda
- Faculty of Informatics and Engineering, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
| | - Tingli Ma
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu-shi, Fukuoka-ken 808-0196, Japan
| | - Dong-Won Kang
- School of Energy Systems Engineering, Chung-Ang University, Seoul 06974, South Korea
| | - Shuzi Hayase
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu-shi, Fukuoka-ken 808-0196, Japan
- Faculty of Informatics and Engineering, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
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Yuan D, Sharapov V, Liu X, Yu L. Design of High-Performance Organic Light-Emitting Transistors. ACS OMEGA 2020; 5:68-74. [PMID: 31956752 PMCID: PMC6963901 DOI: 10.1021/acsomega.9b03630] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 12/04/2019] [Indexed: 05/31/2023]
Abstract
Organic light-emitting transistors (OLETs) integrate the light-emitting and gate-modulated electrical switching functions in a single device. Over the past decades, progress has been made in developing new fluorescent semiconductors and device engineering that pushed efficiencies of OLET devices to 8%. However, this efficiency of transistors is still too low to be competitive with organic light-emitting diodes (OLEDs). Currently, there are relatively few suitable organic fluorescent semiconductors suitable for OLETs, and the mechanism of electroluminescence in the devices is still not fully understood. In this mini-review, we discuss the state of highly efficient OLETs and plausible approaches to those unsettled problems. Since this is a mini-review, we will not be able to cover all the excellent work in the literature. Readers are encouraged to read other excellent reviews published earlier.
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Daskalakis KS, Freire-Fernández F, Moilanen AJ, van Dijken S, Törmä P. Converting an Organic Light-Emitting Diode from Blue to White with Bragg Modes. ACS PHOTONICS 2019; 6:2655-2662. [PMID: 31788498 PMCID: PMC6875896 DOI: 10.1021/acsphotonics.9b01206] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Indexed: 05/10/2023]
Abstract
Organic light-emitting diodes (OLEDs) have been established as versatile light sources that allow for easy integration in large-area surfaces and flexible substrates. In addition, the low fabrication cost of OLEDs renders them particularly attractive as general lighting sources. Current methods for the fabrication of white-light OLEDs rely on the combination of multiple organic emitters and/or the incorporation of multiple cavity modes in a thick active medium. These architectures introduce formidable challenges in both device design and performance improvements, namely, the decrease of efficiency with increasing brightness (efficiency roll-off) and short operational lifetime. Here we demonstrate, for the first time, white-light generation in an OLED consisting of a sub-100 nm thick blue single-emissive layer coupled to the photonic Bragg modes of a dielectric distributed Bragg reflector (DBR). We show that the Bragg modes, although primarily located inside the DBR stack, can significantly overlap with the emissive layer, thus efficiently enhancing emission and outcoupling of photons at selected wavelengths across the entire visible light spectrum. Moreover, we show that color temperature can be tuned by the DBR parameters, offering great versatility in the optimization of white-light emission spectra.
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Cao HT, Hong CS, Ye DQ, Liu LH, Xie LH, Chen SF, Sun C, Wang SS, Zhang HM, Huang W. Tetracyano-substituted spiro[fluorene-9,9′-xanthene] as electron acceptor for exciplex thermally activated delayed fluorescence. J Mol Struct 2019. [DOI: 10.1016/j.molstruc.2019.06.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Lee CY, Naik Mude N, Lampande R, Eun KJ, Yeom JE, Choi HS, Sohn SH, Yoo JM, Kwon JH. Efficient Cadmium-Free Inverted Red Quantum Dot Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2019; 11:36917-36924. [PMID: 31529962 DOI: 10.1021/acsami.9b12514] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Here, we report an efficient inverted red indium phosphide (InP) comprising QD (InP/ZnSe/ZnS, core/shell structure) light-emitting diode (QLED) by modulating an interfacial contact between the electron transport layer and emissive InP-QDs and applying self-aging approach. The red InP-QLED with optimized interfacial contact exhibits a significant improvement in maximum external quantum efficiency and current efficiency from 4.42 to 10.2% and 4.70 to 10.8 cd/A, respectively, after 69 days of self-aging, which is an almost 2.3-fold improvement compared to the fresh device. The analysis indicates the consecutive reduction in electron injection and accumulation in the emissive QD due to changes in the conduction band minimum of ZnMgO (0.1 eV after 10 days of storage) through a downward vacuum-level shift according to the aging times. During the device aging periods, the oxygen vacancy of ZnMgO reduces, which leads to lower the conductivity of ZnMgO. As a result, charge balance of the device is improved with the suppression of exciton quenching at the interface of ZnMgO and InP-QD.
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Affiliation(s)
- Chae Young Lee
- Department of Information Display , Kyung Hee University , 26, Kyungheedae-ro , Dongdaemoon-gu, Seoul 02447 , Republic of Korea
| | - Nagarjuna Naik Mude
- Department of Information Display , Kyung Hee University , 26, Kyungheedae-ro , Dongdaemoon-gu, Seoul 02447 , Republic of Korea
| | - Raju Lampande
- Department of Information Display , Kyung Hee University , 26, Kyungheedae-ro , Dongdaemoon-gu, Seoul 02447 , Republic of Korea
| | - Kwan Ju Eun
- Department of Information Display , Kyung Hee University , 26, Kyungheedae-ro , Dongdaemoon-gu, Seoul 02447 , Republic of Korea
| | - Ji Eun Yeom
- Department of Information Display , Kyung Hee University , 26, Kyungheedae-ro , Dongdaemoon-gu, Seoul 02447 , Republic of Korea
| | - Hyung Sik Choi
- Research and Development Team, Visual Display , Samsung Electronics Co., Ltd , 129, Samsung-ro , Yeongtong-gu, Suwon 16677 , Republic of Korea
| | - Sang Hyun Sohn
- Research and Development Team, Visual Display , Samsung Electronics Co., Ltd , 129, Samsung-ro , Yeongtong-gu, Suwon 16677 , Republic of Korea
| | - Jun Mo Yoo
- Research and Development Team, Visual Display , Samsung Electronics Co., Ltd , 129, Samsung-ro , Yeongtong-gu, Suwon 16677 , Republic of Korea
| | - Jang Hyuk Kwon
- Department of Information Display , Kyung Hee University , 26, Kyungheedae-ro , Dongdaemoon-gu, Seoul 02447 , Republic of Korea
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Liu CF, Liu X, Lai WY, Huang W. Organic Light-Emitting Field-Effect Transistors: Device Geometries and Fabrication Techniques. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1802466. [PMID: 30101548 DOI: 10.1002/adma.201802466] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 05/21/2018] [Indexed: 06/08/2023]
Abstract
Organic light-emitting transistors (OLETs), as novel and attractive kinds of organic electronic devices, have gained extensive attention from both academia and industry. The unique device architectures can simultaneously combine the electrical switching functionality of organic field-effect transistors and the light generation capability of organic light-emitting diodes in a single device, thereby holding great promise for reducing the complicated processes of next-generation pixel circuitry. This review involves the design, fabrication, and applications of OLETs with a comprehensive coverage of this field with the aim to give a deep insight into the intrinsic mechanisms of devices. Challenges and future prospects of OLETs are also discussed.
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Affiliation(s)
- Cheng-Fang Liu
- Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing, 210023, China
| | - Xu Liu
- Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing, 210023, China
| | - Wen-Yong Lai
- Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing, 210023, China
- Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University (NPU), 127, West Youyi Road, Xi'an, 710072, Shaanxi, China
| | - Wei Huang
- Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing, 210023, China
- Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University (NPU), 127, West Youyi Road, Xi'an, 710072, Shaanxi, China
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Pander P, Gogoc S, Colella M, Data P, Dias FB. Thermally Activated Delayed Fluorescence in Polymer-Small-Molecule Exciplex Blends for Solution-Processed Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2018; 10:28796-28802. [PMID: 30044613 DOI: 10.1021/acsami.8b07554] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The photophysics of an exciplex state formed between a small molecule and a polymer is investigated in this work. The results obtained with this blend show the strong potential of polymer-small-molecule blends for triplet harvesting in organic light-emitting diodes (OLEDs) via thermally activated delayed fluorescence. The exciplex formed between poly( N-vinylcarbazole) (PVK) and 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T) shows yellow-green emission and is applied in solution-processed OLEDs. The excellent film-forming properties in this blend allow easy spin coating and potential use in other solution-processing techniques, such as slot die coating. In this work, we critically address the reverse intersystem crossing mechanism in the presented exciplex system, including the role of local triplet states. Moreover, we bring a clear physical meaning to the decay components of the exciplex emission, including the decay occurring in a power-law fashion that is often ignored in the literature.
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Affiliation(s)
- Piotr Pander
- Department of Physics , Durham University , South Road , Durham DH1 3LE , United Kingdom
| | - Szymon Gogoc
- Faculty of Chemistry , Silesian University of Technology , Ks. M. Strzody 9 , 44-100 Gliwice , Poland
| | - Marco Colella
- Department of Physics , Durham University , South Road , Durham DH1 3LE , United Kingdom
| | - Przemyslaw Data
- Department of Physics , Durham University , South Road , Durham DH1 3LE , United Kingdom
- Faculty of Chemistry , Silesian University of Technology , Ks. M. Strzody 9 , 44-100 Gliwice , Poland
- Centre of Polymer and Carbon Materials , Polish Academy of Sciences , M. Sklodowskiej-Curie 34 , 41-819 Zabrze , Poland
| | - Fernando B Dias
- Department of Physics , Durham University , South Road , Durham DH1 3LE , United Kingdom
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Sarma M, Wong KT. Exciplex: An Intermolecular Charge-Transfer Approach for TADF. ACS APPLIED MATERIALS & INTERFACES 2018; 10:19279-19304. [PMID: 29613766 DOI: 10.1021/acsami.7b18318] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Organic materials that display thermally activated delayed fluorescence (TADF) are a striking class of functional materials that have witnessed a booming progress in recent years. In addition to pure TADF emitters achieved by the subtle manipulations of intramolecular charge transfer processes with sophisticated molecular structures, a new class of efficient TADF-based OLEDs with emitting layer formed by blending electron donor and acceptor molecules that involve intermolecular charge transfer have also been fabricated. In contrast to pure TADF materials, the exciplex-based systems can realize small Δ EST (0-0.05 eV) much more easily since the electron and hole are positioned on two different molecules, thereby giving small exchange energy. Consequently, exciplex-based OLEDs have the prospective to maximize the TADF contribution and achieve theoretical 100% internal quantum efficiency. Therefore, the challenging issue of achieving small Δ EST in organic systems could be solved. In this article, we summarize and discuss the latest and most significant developments regarding these rapidly evolving functional materials, wherein the majority of the reported exciplex forming systems are categorized into two subgroups, viz. (a) exciplex as TADF emitters and (b) those as hosts for fluorescent, phosphorescent and TADF dopants according to their structural features and applications. The working mechanisms of the direct electroluminescence from the donor/acceptor interface and the exciplex-forming systems as cohost for the realization of high efficiency OLEDs are reviewed and discussed. This article delivers a summary of the current progresses and achievements of exciplex-based researches and points out the future challenges to trigger more research endeavors to this growing field.
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Affiliation(s)
- Monima Sarma
- Department of Chemistry , National Taiwan University , Taipei 10617 , Taiwan
| | - Ken-Tsung Wong
- Department of Chemistry , National Taiwan University , Taipei 10617 , Taiwan
- Institute of Atomic and Molecular Science , Academia Sinica , Taipei 10617 , Taiwan
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