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Zhang Q, Zhang D, Cao B, Poddar S, Mo X, Fan Z. Improving the Operational Lifetime of Metal-Halide Perovskite Light-Emitting Diodes with Dimension Control and Ligand Engineering. ACS Nano 2024; 18:8557-8570. [PMID: 38482819 DOI: 10.1021/acsnano.3c13136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
Perovskite light-emitting diodes (LEDs) have emerged as one of the most propitious candidates for next-generation lighting and displays, with the highest external quantum efficiency (EQE) of perovskite LEDs already surpassing the 20% milestone. However, the further development of perovskite LEDs primarily relies on addressing operational instability issues. This Perspective examines some of the key factors that impact the lifetime of perovskite LED devices and some representative reports on recent advancements aimed at improving the lifetime. Our analysis underscores the significance of "nano" strategies in achieving long-term stable perovskite LEDs. Significant efforts must be directed toward proper device encapsulation, perovskite material passivation, interfacial treatment to address environment-induced material instability, bias-induced phase separation, and ion migration issues.
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Affiliation(s)
- Qianpeng Zhang
- State Key Laboratory of Photovoltaic Science and Technology, Shanghai Frontiers Science Research Base of Intelligent Optoelectronics and Perception, Institute of Optoelectronics, Fudan University, Shanghai 200433, China
- Department of Electronic & Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
- State Key Laboratory of Advanced Displays and Optoelectronics Technologies, The Hong Kong University of Science and Technology; Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Daquan Zhang
- Department of Electronic & Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
- State Key Laboratory of Advanced Displays and Optoelectronics Technologies, The Hong Kong University of Science and Technology; Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Bryan Cao
- Department of Electronic & Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Swapnadeep Poddar
- Department of Electronic & Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Xiaoliang Mo
- State Key Laboratory of Photovoltaic Science and Technology, Shanghai Frontiers Science Research Base of Intelligent Optoelectronics and Perception, Institute of Optoelectronics, Fudan University, Shanghai 200433, China
| | - Zhiyong Fan
- Department of Electronic & Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
- State Key Laboratory of Advanced Displays and Optoelectronics Technologies, The Hong Kong University of Science and Technology; Clear Water Bay, Kowloon, Hong Kong SAR, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
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Nikul'shin PV, Fedunov RG, Kuibida LV, Maksimov AM, Glebov EM, Stass DV. Recombination of X-ray-Generated Radical Ion Pairs in Alkane Solution Assembles Optically Inaccessible Exciplexes from a Series of Perfluorinated para-Oligophenylenes with N, N-Dimethylaniline. Int J Mol Sci 2023; 24:ijms24087568. [PMID: 37108728 PMCID: PMC10142361 DOI: 10.3390/ijms24087568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 04/14/2023] [Accepted: 04/18/2023] [Indexed: 04/29/2023] Open
Abstract
We demonstrate that a series of perfluorinated para-oligophenylenes C6F5-(C6F4)n-C6F5 (n = 1-3) produce exciplexes with N,N-dimethylaniline (DMA) in degassed X-irradiated n-dodecane solutions. The optical characterization of the compounds shows that their short fluorescence lifetimes (ca. 1.2 ns) and UV-Vis absorption spectra, overlapping with the spectrum of DMA with molar absorption coefficients of 2.7-4.6 × 104 M-1cm-1, preclude the standard photochemical exciplex formation pathway via selective optical generation of the local excited state of the donor and its bulk quenching by the acceptor. However, under X-rays, the efficient assembly of such exciplexes proceeds via the recombination of radical ion pairs, which delivers the two partners close to each other and ensures a sufficient energy deposition. The exciplex emission is completely quenched by the equilibration of the solution with air, providing a lower bound of exciplex emission lifetime of ca. 200 ns. The recombination nature of the exciplexes is confirmed by the magnetic field sensitivity of the exciplex emission band inherited from the magnetic field sensitivity from the recombination of spin-correlated radical ion pairs. Exciplex formation in such systems is further supported by DFT calculations. These first exciplexes from fully fluorinated compounds show the largest known red shift of the exciplex emission from the local emission band, suggesting the potential of perfluoro compounds for optimizing optical emitters.
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Affiliation(s)
- Pavel V Nikul'shin
- A.V. Topchiev Institute of Petrochemical Synthesis, 119991 Moscow, Russia
| | - Roman G Fedunov
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russia
| | - Leonid V Kuibida
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russia
| | - Alexander M Maksimov
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, 630090 Novosibirsk, Russia
| | - Evgeni M Glebov
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Dmitri V Stass
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russia
- International Tomography Center, 630090 Novosibirsk, Russia
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3
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Shao J, Chen C, Zhao W, Zhang E, Ma W, Sun Y, Chen P, Sheng R. Recent Advances of Interface Exciplex in Organic Light-Emitting Diodes. Micromachines 2022; 13:298. [PMID: 35208422 PMCID: PMC8875368 DOI: 10.3390/mi13020298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 02/05/2022] [Accepted: 02/07/2022] [Indexed: 02/06/2023]
Abstract
The interface exciplex system is a promising technology for reaching organic light-emitting diodes (OLEDs) with low turn-on voltages, high efficiencies and long lifetimes due to its unique virtue of barrier-free charge transport, well-confined recombination region, and thermally activated delayed fluorescence characteristics. In this review, we firstly illustrate the mechanism frameworks and superiorities of the interface exciplex system. We then summarize the primary applications of interface exciplex systems fabricated by doping and doping-free technologies. The operation mechanisms of these OLEDs are emphasized briefly. In addition, various novel strategies for further improving the performances of interface exciplex-based devices are demonstrated. We believe this review will give a promising perspective and attract researchers to further develop this technology in the future.
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Albrecht K, Hisamura E, Furukori M, Nakayama Y, Hosokai T, Nakao K, Ikebe H, Nakayama A. Thermally Activated Delayed Fluorescence of Carbazole-Benzophenone Dendrimer with Bulky Substituents. Polym Chem 2022. [DOI: 10.1039/d2py00255h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Carbazole dendrimers with benzophenone core and bulky terminal substituents were synthesized, and thermally-activated delayed fluorescence (TADF) property was investigated. The adamantane (Ad) substituted dendrimer showed green TADF emission with PLQY...
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Vasilopoulou M, Mohd Yusoff ARB, Daboczi M, Conforto J, Gavim AEX, da Silva WJ, Macedo AG, Soultati A, Pistolis G, Schneider FK, Dong Y, Jacoutot P, Rotas G, Jang J, Vougioukalakis GC, Chochos CL, Kim JS, Gasparini N. High efficiency blue organic light-emitting diodes with below-bandgap electroluminescence. Nat Commun 2021; 12:4868. [PMID: 34381038 PMCID: PMC8357948 DOI: 10.1038/s41467-021-25135-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 07/20/2021] [Indexed: 11/09/2022] Open
Abstract
Blue organic light-emitting diodes require high triplet interlayer materials, which induce large energetic barriers at the interfaces resulting in high device voltages and reduced efficiencies. Here, we alleviate this issue by designing a low triplet energy hole transporting interlayer with high mobility, combined with an interface exciplex that confines excitons at the emissive layer/electron transporting material interface. As a result, blue thermally activated delay fluorescent organic light-emitting diodes with a below-bandgap turn-on voltage of 2.5 V and an external quantum efficiency (EQE) of 41.2% were successfully fabricated. These devices also showed suppressed efficiency roll-off maintaining an EQE of 34.8% at 1000 cd m−2. Our approach paves the way for further progress through exploring alternative device engineering approaches instead of only focusing on the demanding synthesis of organic compounds with complex structures. Thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs) rely on high triplet energy interlayers to confine excitons, which results in reduced performance. Here, the authors report high-performance blue TADF-OLEDs with below bandgap electroluminescence.
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Affiliation(s)
- Maria Vasilopoulou
- Institute of Nanoscience and Nanotechnology, National Centre for Scientific Research Demokritos, Terma Patriarchou Grigoriou, Agia Paraskevi, Greece.
| | - Abd Rashid Bin Mohd Yusoff
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Republic of Korea.
| | - Matyas Daboczi
- Department of Physics and Centre for Processable Electronics, Imperial College London, London, UK
| | - Julio Conforto
- Universidade Tecnologica Federal do Parana, GPGEI, Curitiba, Parana, Brazil
| | | | | | | | - Anastasia Soultati
- Institute of Nanoscience and Nanotechnology, National Centre for Scientific Research Demokritos, Terma Patriarchou Grigoriou, Agia Paraskevi, Greece
| | - George Pistolis
- Institute of Nanoscience and Nanotechnology, National Centre for Scientific Research Demokritos, Terma Patriarchou Grigoriou, Agia Paraskevi, Greece
| | | | - Yifan Dong
- Department of Chemistry and Centre for Processable Electronics, Imperial College London, London, UK
| | - Polina Jacoutot
- Department of Chemistry and Centre for Processable Electronics, Imperial College London, London, UK
| | - Georgios Rotas
- Department of Chemistry, National and Kapodistrian University of Athens, Athens, Greece
| | - Jin Jang
- Advanced Display Research Center, Department of Information Display, Kyung Hee University, Dongdaemoon-gu, Seoul, South Korea
| | | | - Christos L Chochos
- Institute of Chemical Biology, National Hellenic Research Foundation, Athens, Greece.
| | - Ji-Seon Kim
- Department of Physics and Centre for Processable Electronics, Imperial College London, London, UK
| | - Nicola Gasparini
- Department of Chemistry and Centre for Processable Electronics, Imperial College London, London, UK.
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Tan S, Jinnai K, Kabe R, Adachi C. Long-Persistent Luminescence from an Exciplex-Based Organic Light-Emitting Diode. Adv Mater 2021; 33:e2008844. [PMID: 33945182 DOI: 10.1002/adma.202008844] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/21/2021] [Indexed: 06/12/2023]
Abstract
Organic long-persistent luminescent systems (OLPLs) exhibiting long-lasting emission after photoexcitation consist of organic electron donors and acceptors, that are widely used in organic light-emitting diodes (OLEDs). Although OLPLs and OLEDs include very similar excitonic processes, long-lasting emission has never been observed in OLEDs. This study confirms the presence of long-persistent luminescence (LPL) under electrical excitation.
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Affiliation(s)
- Shinichi Tan
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
- JST, ERATO, Adachi Molecular Exciton Engineering Project, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Kazuya Jinnai
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
- JST, ERATO, Adachi Molecular Exciton Engineering Project, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Ryota Kabe
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
- JST, ERATO, Adachi Molecular Exciton Engineering Project, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
- Organic Optoelectronics Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son Kunigami-gun, Okinawa, 904-0495, Japan
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
- JST, ERATO, Adachi Molecular Exciton Engineering Project, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
- International Institute for Carbon Neutral Energy Research (I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
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Hempe M, Kukhta NA, Danos A, Fox MA, Batsanov AS, Monkman AP, Bryce MR. Vibrational Damping Reveals Vibronic Coupling in Thermally Activated Delayed Fluorescence Materials. Chem Mater 2021; 33:3066-3080. [PMID: 34267422 PMCID: PMC8273894 DOI: 10.1021/acs.chemmater.0c03783] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 04/05/2021] [Indexed: 05/18/2023]
Abstract
We investigate a series of D-A molecules consisting of spiro[acridan-9,9'-fluorene] as the donor and 2-phenylenepyrimidine as the acceptor. In two of the materials, a spiro center effectively electronically isolates the D unit from (consequently) optically innocent yet structurally influential adamantyl side groups. In a third material, adamantyl groups attached directly to the acceptor strongly influence the electronic properties. Steady-state and time-resolved photophysical studies in solution, Zeonex polymer matrix, and neat films reveal that the substituents impact the efficiency of vibronic coupling between singlet and triplet states relevant to reverse intersystem crossing (rISC) and thermally activated delayed fluorescence (TADF), without significantly changing the singlet-triplet gap in the materials. The adamantyl groups serve to raise the segmental mass and inertia, thereby damping intramolecular motions (both vibrational and rotational). This substitution pattern reveals the role of large-amplitude (primarily D-A dihedral angle rocking) motions on reverse intersystem crossing (rISC), as well as smaller contributions from low-amplitude or dampened vibrations in solid state. We demonstrate that rISC still occurs when the high-amplitude motions are suppressed in Zeonex and discuss various vibronic coupling scenarios that point to an underappreciated role of intersegmental motions that persist in rigid solids. Our results underline the complexity of vibronic couplings in the mediation of rISC and provide a synthetic tool to enable future investigations of vibronic coupling through selective mechanical dampening with no impact on electronic systems.
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Affiliation(s)
- Matthias Hempe
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Nadzeya A. Kukhta
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Andrew Danos
- Physics
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Mark A. Fox
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Andrei S. Batsanov
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Andrew P. Monkman
- Physics
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Martin R. Bryce
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
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8
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Peng CC, Yang SY, Li HC, Xie GH, Cui LS, Zou SN, Poriel C, Jiang ZQ, Liao LS. Highly Efficient Thermally Activated Delayed Fluorescence via an Unconjugated Donor-Acceptor System Realizing EQE of Over 30. Adv Mater 2020; 32:e2003885. [PMID: 33118645 DOI: 10.1002/adma.202003885] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 09/24/2020] [Indexed: 06/11/2023]
Abstract
In this work, two novel thermally activated delayed fluorescence (TADF) emitters, 2tDMG and 3tDMG, are synthesized for high-efficiency organic light-emitting diodes (OLEDs), The two emitters have a tilted face-to-face alignment of donor (D)/acceptor (A) units presenting intramolecular noncovalent interactions. The two TADF materials are deposited either by an evaporation-process or by a solution-process, both of them leading to high OLED performance. 2tDMG used as the emitter in evaporation-processed OLEDs achieves a high external quantum efficiency (EQE) of 30.8% with a very flat efficiency roll-off of 7% at 1000 cd m-2 . The solution-processed OLEDs also display an interesting EQE of 16.2%. 3tDMG shows improved solubility and solution processability as compared to 2tDMG, and thus a high EQE of 20.2% in solution-processed OLEDs is recorded. The corresponding evaporation-processed OLEDs also reach a reasonably high EQE of 26.3%. Encouragingly, this work provides a novel strategy to address the imperious demands for OLEDs with high EQE and low roll-off.
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Affiliation(s)
- Chen-Chen Peng
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu, 215123, P. R. China
| | - Sheng-Yi Yang
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu, 215123, P. R. China
| | - Hong-Cheng Li
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu, 215123, P. R. China
| | - Guo-Hua Xie
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan, 430072, P. R. China
| | - Lin-Song Cui
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Sheng-Nan Zou
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu, 215123, P. R. China
| | - Cyril Poriel
- Univ Rennes, CNRS, ISCR-UMR 6226, Rennes, 35000, France
| | - Zuo-Quan Jiang
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu, 215123, P. R. China
| | - Liang-Sheng Liao
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu, 215123, P. R. China
- Institute of Organic Optoelectronics, Jiangsu Industrial Technology Research Institute (JITRI), Suzhou, Jiangsu, 215211, P. R. China
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Stavrou K, Franca LG, Monkman AP. Photophysics of TADF Guest-Host Systems: Introducing the Idea of Hosting Potential. ACS Appl Electron Mater 2020; 2:2868-2881. [PMID: 32984822 PMCID: PMC7513578 DOI: 10.1021/acsaelm.0c00514] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 08/11/2020] [Indexed: 05/29/2023]
Abstract
The thermally activated delayed fluorescence (TADF) donor-acceptor (D-A) molecule, DMAC-TRZ, is used as a TADF emitter "probe" to distinguish the environmental effects of a range of solid-state host materials in guest-host systems. Using the guest's photophysical behavior in solution as a benchmark, a comprehensive study using a variety of typical TADF organic light-emitting diode hosts with different characteristics provides a clearer understanding of guest-host interactions and what affects emitter performance in solid state. We investigate which are the key host characteristics that directly affect charge-transfer (CT) state energy and singlet triplet energy gaps. Using time-resolved photoluminescence measurements, we use the CT state energy distribution obtained from the full width at half-maximum (fwhm) of the emission band and correlate this with other photophysical properties such as the apparent dynamic red shift of CT emission on-set to estimate the disorder-induced heterogeneity of D-A dihedral angles and singlet triplet gaps. Further, the delayed emission stabilization energy value and time-dependent CT band fwhm are shown to be related to a combination of host's rigidity, emitter molecule packing, and the energy difference between guest and host lowest energy triplet states. Concentration dependence studies show that emitter dimerization/aggregation can improve as well as reduce emission efficiency depending on the characteristics of the host. Two similar host materials, mCPCN and mCBPCN, with optimum host characteristics show completely different behaviors, and their hosting potential is extensively explored. We demonstrate that type I and type III TADF emitters behave differently in the same host and that the materials with intrinsic small ΔE ST have the smallest disorder-induced CT energy and reverse intersystem crossing rate dispersion. We also present an optimized method to define the actual triplet energy of a guest-host system, a crucial parameter in understanding the overall mechanism of the TADF efficiency of the system.
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Chen R, Liu C, Asare-Yeboah K, Zhang Z, He Z, Liu Y. Retracted Article: Wavelength modulation of ZnO nanowire based organic light-emitting diodes with ultraviolet electroluminescence. RSC Adv 2020; 10:23775-23781. [PMID: 35517321 PMCID: PMC9054857 DOI: 10.1039/d0ra04058d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 06/17/2020] [Indexed: 01/17/2023] Open
Abstract
Although organic light emitting diodes (OLEDs) can find important applications in display-related fields, it still remains a challenge to fabricate high-efficiency ultraviolet (UV) OLEDs with tunable wavelength. In this work, we demonstrate a facile method to adjust the electroluminescence (EL) peak from an inverted UV-OLED device that has zinc oxide nanowires (ZnO NWs) as an electron injection layer. The organic–inorganic interface between ZnO NWs and the 3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ) emission layer employed in this work allows a reduction of the diffusion length of excitons, which further results in a hampered relaxation process of higher energy states as well as a blue shift of the EL spectrum. As a result, the emission peaks of the UV-OLED can be easily adjusted from 383 nm to 374 nm by tuning both the length of the ZnO NWs and the thickness of the TAZ emission layer. Our work reveals an important correlation between emission peaks and exciton diffusion, and presents a novel approach to fabricate high-performance UV-OLEDs with the capability of facilely modifying the emission wavelength. As organic light emitting diodes (OLEDs) find important applications in display-related fields, we demonstrate the fabrication of an inverted UV-OLED device with tunable wavelength that composes zinc oxide nanowires as an electron injection layer.![]()
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Affiliation(s)
- Runze Chen
- Leicester International Institute
- Dalian University of Technology
- Panjin City
- China
| | - Chuan Liu
- State Key Laboratory of Structural Analysis for Industrial Equipment
- Dalian University of Technology
- Dalian 116024
- China
| | | | - Ziyang Zhang
- Department of Electrical Engineering
- Columbia University
- New York City
- USA
| | - Zhengran He
- Department of Electrical and Computer Engineering
- The University of Alabama
- Tuscaloosa
- USA
| | - Yun Liu
- Department of Physics
- Dalian University of Technology
- Dalian 116024
- China
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11
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Zhong D, Yu Y, Song D, Yang X, Zhang Y, Chen X, Zhou G, Wu Z. Organic Emitters with a Rigid 9-Phenyl-9-phosphafluorene Oxide Moiety as the Acceptor and Their Thermally Activated Delayed Fluorescence Behavior. ACS Appl Mater Interfaces 2019; 11:27112-27124. [PMID: 31271029 DOI: 10.1021/acsami.9b05950] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
With the 9-phenyl-9-phosphafluorene oxide (PhFlOP) moiety as the acceptor (A) and various donors (D), a series of new organic emitters have been synthesized with a D-A-D configuration. Their photophysical and electrochemical behaviors and electroluminescent (EL) performances have been characterized in detail. The photophysical results have indicated that the PhFlOP-based emitters with acridyl, phenoxazyl, and phenothiazyl as donors show efficient, thermally activated delayed fluorescence (TADF) behavior, especially for the TADF emitter with the phenoxazyl donor possessing an exceptionally high rate constant of reverse intersystem crossing (kRISC) of 6.2 × 105 s-1. It has also been found that their TADF behavior can be greatly affected by the substitution position of the donors. Different from the reported aryl phosphine oxide (APO) acceptors in TADF emitters, the PhFlOP moiety adopts a highly rigid configuration to guarantee a photoluminescent quantum yield as high as 0.80 in the 4,4'-N,N'-dicarbazolebiphenyl film, representing the top-ranking emission ability for the TADF emitters with APO-type acceptors. Benefitting from their advanced TADF performances, the doped organic light-emitting diodes/devices based on these PhFlOP-based TADF emitters can achieve exceptional EL performances with the maximum external quantum efficiency (ηext) of 23.3%, current efficiency (ηL) of 83.7 cd A-1, and power efficiency (ηP) of 59.1 lm W-1. These encouraging EL data show the great potential of the PhFlOP moiety in developing highly efficient TADF emitters.
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Affiliation(s)
| | - Yue Yu
- School of Physics and Optoelectronic Engineering , Xidian University , Xi'an 710071 , P. R. China
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12
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Zhang M, Liu W, Zheng C, Wang K, Shi Y, Li X, Lin H, Tao S, Zhang X. Tricomponent Exciplex Emitter Realizing over 20% External Quantum Efficiency in Organic Light-Emitting Diode with Multiple Reverse Intersystem Crossing Channels. Adv Sci (Weinh) 2019; 6:1801938. [PMID: 31380198 PMCID: PMC6661936 DOI: 10.1002/advs.201801938] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 04/11/2019] [Indexed: 06/10/2023]
Abstract
With the naturally separated frontier molecular orbitals, exciplexes are capable of thermally activated delayed fluorescence emitters for organic light-emitting diodes (OLEDs). And, the current key issue for exciplex emitters is improving their exciton utilization. In this work, a strategy of building exciplex emitters with three components is proposed to realize multiple reverse intersystem crossing (RISC) channels, improving their exciton utilization by enhancing upconversion of nonradiative triplet excitons. Accordingly, a tricomponent exciplex DBT-SADF:PO-T2T:CDBP is constructed with three RISC channels respectively on DBT-SADF, DBT-SADF:PO-T2T, and CDBP:PO-T2T. Furthermore, its photoluminescence quantum yield and rate constant of the RISC process are successfully improved. In the OLED, DBT-SADF:PO-T2T:CDBP exhibits a remarkably high maximum external quantum efficiency (EQE) of 20.5%, which is the first report with an EQE over 20% for the OLEDs based on exciplex emitters to the best of our knowledge. This work not only demonstrates that introducing multiple RISC channels can effectively improve the exciton utilization of exciplex emitters, but also proves the superiority of the tricomponent exciplex strategy for further development of exciplex emitters.
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Affiliation(s)
- Ming Zhang
- School of Optoelectronic Science and EngineeringUniversity of Electronic Science and Technology of China (UESTC)Chengdu610054P. R. China
- Institute of Functional Nano & Soft Materials (FUNSOM)Soochow UniversitySuzhou215123P. R. China
| | - Wei Liu
- Institute of Functional Nano & Soft Materials (FUNSOM)Soochow UniversitySuzhou215123P. R. China
| | - Cai‐Jun Zheng
- School of Optoelectronic Science and EngineeringUniversity of Electronic Science and Technology of China (UESTC)Chengdu610054P. R. China
| | - Kai Wang
- Institute of Functional Nano & Soft Materials (FUNSOM)Soochow UniversitySuzhou215123P. R. China
| | - Yi‐Zhong Shi
- Institute of Functional Nano & Soft Materials (FUNSOM)Soochow UniversitySuzhou215123P. R. China
| | - Xing Li
- Institute of Functional Nano & Soft Materials (FUNSOM)Soochow UniversitySuzhou215123P. R. China
| | - Hui Lin
- School of Optoelectronic Science and EngineeringUniversity of Electronic Science and Technology of China (UESTC)Chengdu610054P. R. China
| | - Si‐Lu Tao
- School of Optoelectronic Science and EngineeringUniversity of Electronic Science and Technology of China (UESTC)Chengdu610054P. R. China
| | - Xiao‐Hong Zhang
- Institute of Functional Nano & Soft Materials (FUNSOM)Soochow UniversitySuzhou215123P. R. China
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Cai M, Zhang D, Duan L. High Performance Thermally Activated Delayed Fluorescence Sensitized Organic Light‐Emitting Diodes. CHEM REC 2018; 19:1611-1623. [DOI: 10.1002/tcr.201800148] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/23/2018] [Indexed: 01/22/2023]
Affiliation(s)
- Minghan Cai
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of EducationDepartment of ChemistryTsinghua University Beijing 100084 China
| | - Dongdong Zhang
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of EducationDepartment of ChemistryTsinghua University Beijing 100084 China
| | - Lian Duan
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of EducationDepartment of ChemistryTsinghua University Beijing 100084 China
- Center for Flexible Electronics TechnologyTsinghua University Beijing 100084 China
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