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Wu Y, Xin Y, Pan Y, Yiu S, Yan J, Lau KC, Duan L, Chi Y. Ir(III) Metal Emitters with Cyano-Modified Imidazo[4,5-b]pyridin-2-ylidene Chelates for Deep-Blue Organic Light-Emitting Diodes. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2309389. [PMID: 38689505 PMCID: PMC11234470 DOI: 10.1002/advs.202309389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 03/15/2024] [Indexed: 05/02/2024]
Abstract
Ir(III) carbene complexes have been explored as one of the best blue phosphors for their high performance. Herein, the authors designed and synthesized a series of blue-emitting Ir(III) phosphors (f-ct9a-c), featuring fac-coordinated cyano-imidazo[4,5-b]pyridin-2-ylidene cyclometalates. These Ir(III) complexes exhibit true-blue emission with a peak maximum spanning 448-467 nm, with high photoluminescence quantum yields of 81-88% recorded in degassed toluene. Moreover, OLED devices bearing phosphors f-ct9a and f-ct9b deliver maximum external quantum efficiencies (EQEmax) of 25.9% and 30.3%, together with Commission Internationale de L'Eclairage (CIEx,y) coordinates of (0.157, 0.225) and (0.142, 0.169), respectively. Remarkably, the f-ct9b-based device displays an incredible EQE of 29.0% at 5000 cd·m-2. The hyper-OLED device based on f-ct9b and ν-DABNA exhibits an EQEmax of 34.7% and CIEx,y coordinates of (0.122, 0.131), affirming high potentials in achieving efficient blue electroluminescence.
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Affiliation(s)
- Yixin Wu
- Department of ChemistryDepartment of Materials Science and EngineeringCenter of Super‐Diamond and Advanced Films (COSDAF)City University of Hong KongHong KongSAR999077China
| | - Yangyang Xin
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of EducationDepartment of ChemistryTsinghua UniversityBeijing100084China
| | - Yi Pan
- Department of ChemistryDepartment of Materials Science and EngineeringCenter of Super‐Diamond and Advanced Films (COSDAF)City University of Hong KongHong KongSAR999077China
| | - Shek‐Man Yiu
- Department of ChemistryDepartment of Materials Science and EngineeringCenter of Super‐Diamond and Advanced Films (COSDAF)City University of Hong KongHong KongSAR999077China
| | - Jie Yan
- Department of ChemistryDepartment of Materials Science and EngineeringCenter of Super‐Diamond and Advanced Films (COSDAF)City University of Hong KongHong KongSAR999077China
| | - Kai Chung Lau
- Department of ChemistryDepartment of Materials Science and EngineeringCenter of Super‐Diamond and Advanced Films (COSDAF)City University of Hong KongHong KongSAR999077China
| | - Lian Duan
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of EducationDepartment of ChemistryTsinghua UniversityBeijing100084China
| | - Yun Chi
- Department of ChemistryDepartment of Materials Science and EngineeringCenter of Super‐Diamond and Advanced Films (COSDAF)City University of Hong KongHong KongSAR999077China
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Wang J, Zou P, Chen L, Bai Z, Liu H, Chen WC, Huo Y, Tang BZ, Zhao Z. Promising interlayer sensitization strategy for the construction of high-performance blue hyperfluorescence OLEDs. LIGHT, SCIENCE & APPLICATIONS 2024; 13:139. [PMID: 38871706 DOI: 10.1038/s41377-024-01490-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 05/09/2024] [Accepted: 05/20/2024] [Indexed: 06/15/2024]
Abstract
Multi-resonance thermally activated delayed fluorescence (MR-TADF) materials are promising candidates for organic light-emitting diodes (OLEDs) with narrow electroluminescence (EL) spectra. Current researches focus on fabricating hyperfluorescence OLEDs to improve EL efficiencies of MR-TADF emitters by co-doping them with TADF sensitizers in a single host layer. However, in many cases, the polarity of the single host could be not suitable for both blue MR-TADF emitters and blue TADF sensitizers, resulting in broadened EL spectra in high-polar hosts or decreased EL efficiencies in low-polar hosts. Herein, we wish to report an efficient sensitization strategy for blue MR-TADF emitters by constructing an interlayer-sensitizing configuration, in which the blue TADF sensitizers and blue MR-TADF emitters are separated into two closely aligned host layers with high polarity and low polarity, respectively. Based on this strategy, efficient blue hyperfluorescence OLEDs are realized and verified by employing various TADF sensitizers and different MR-TADF emitters, furnishing outstanding external quantum efficiencies of up to 38.8% and narrow EL spectra. These results validate the feasibility and universality of this interlayer sensitization strategy, which provides an effective alternative to high-performance blue hyperfluorescence OLEDs.
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Affiliation(s)
- Jianghui Wang
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou, 510640, China
| | - Peng Zou
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou, 510640, China
| | - Letian Chen
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou, 510640, China
| | - Zhentao Bai
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou, 510640, China
| | - Hao Liu
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou, 510640, China
| | - Wen-Cheng Chen
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
| | - Yanping Huo
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
| | - Ben Zhong Tang
- School of Science and Engineering, Shenzhen Institute of Aggregate Science and Technology, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Zujin Zhao
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou, 510640, China.
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Madushani B, Mamada M, Goushi K, Katagiri H, Nakanotani H, Hatakeyama T, Adachi C. Hexacarbazolylbenzene: An Excellent Host Molecule Causing Strong Guest Molecular Orientation and the High-Performance OLEDs. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2402275. [PMID: 38865445 DOI: 10.1002/adma.202402275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 05/19/2024] [Indexed: 06/14/2024]
Abstract
Hexacarbazolylbenzene (6CzPh), which is benzene substituted by six carbazole rings, is a simple and attractive compound. Despite the success of a wide variety of carbazole derivatives in organic light-emitting diodes (OLEDs), 6CzPh has not received attention so far. Here, excellent performances of 6CzPh are revealed as a host material in OLEDs regarding conventional host materials. Various strategies are implemented to improve the performance of OLEDs, e.g., triplet utilization by thermally activated delayed fluorescence (TADF) and phosphorescence emitters for maximizing internal quantum efficiency, and molecular orientation control for increasing outcoupling efficiency. The present host material is suited for both criteria. Robustness of the structure and sufficiently high triplet energy enables a high external quantum efficiency with a long device lifetime. Besides, the host material boosts the horizontal molecular orientations of several guest emitters. It is noteworthy that disk-shaped 4CzIPN marks the complete horizontal molecular orientations (Θh = 100%, S = -0.50). These results provide an effective way of improving efficiencies without sacrificing device durability for future OLEDs.
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Affiliation(s)
- Bhagya Madushani
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Fukuoka, 819-0395, Japan
| | - Masashi Mamada
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Kenichi Goushi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Fukuoka, 819-0395, Japan
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, Nishi, Fukuoka, 819-0395, Japan
| | - Hiroshi Katagiri
- Graduate School of Organic Materials Science, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
| | - Hajime Nakanotani
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Fukuoka, 819-0395, Japan
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, Nishi, Fukuoka, 819-0395, Japan
| | - Takuji Hatakeyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Fukuoka, 819-0395, Japan
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, Nishi, Fukuoka, 819-0395, Japan
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Meng LC, Hou YB. Electric-field modulated energy transfer in phosphorescent material- and fluorescent material-codoped polymer light-emitting diodes. RSC Adv 2024; 14:12294-12302. [PMID: 38633491 PMCID: PMC11019667 DOI: 10.1039/d4ra00669k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 04/05/2024] [Indexed: 04/19/2024] Open
Abstract
The excited-state energy transfer widely exists in mixed-material systems and devices. The modulation of an electric field on the energy transfer in photoluminescence has been demonstrated. However, to date, no studies on the electric-field modulation of the excited-state energy transfer in organic optoelectronic devices have been reported. Herein, we investigate the effect of an electric field on the energy transfer in the poly(N-vinylcarbazole) (PVK) thin films doped with iridium(iii)[bis(4,6-difluorophenyl)pyridinato-N,C2']-tetrakis(1-pyrazolyl)borate (Fir6) and 5,6,11,12-tetraphenylnaphthacene (rubrene) (PVK:Fir6:rubrene) and the corresponding light-emitting diodes. Combined with the Onsager model describing electric-field enhanced exciton dissociation, we find that the electric field increases the rate of Dexter energy transfer from Fir6 to rubrene in the films and the diodes. The voltage-dependent color shift in the PVK:Fir6:rubrene light-emitting diodes can be explained by the electric-field enhanced Dexter energy transfer from Fir6 to rubrene. Our findings are important for the control of energy transfer process in organic optoelectronic devices by an electric field for desirable applications.
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Affiliation(s)
- Ling-Chuan Meng
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University Beijing 100044 PR China
| | - Yan-Bing Hou
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University Beijing 100044 PR China
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5
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Yan J, Feng ZQ, Wu Y, Zhou DY, Yiu SM, Chan CY, Pan Y, Lau KC, Liao LS, Chi Y. Blue Electrophosphorescence from Iridium(III) Phosphors Bearing Asymmetric Di-N-aryl 6-(trifluoromethyl)-2H-imidazo[4,5-b]pyridin-2-ylidene Chelates. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2305273. [PMID: 37461316 DOI: 10.1002/adma.202305273] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/09/2023] [Accepted: 07/14/2023] [Indexed: 09/22/2023]
Abstract
Efficient blue phosphors remain a formidable challenge for organic light-emitting diodes (OLEDs). To circumvent this obstacle, a series of Ir(III)-based carbene complexes bearing asymmetric di-N-aryl 6-(trifluoromethyl)-2H-imidazo[4,5-b]pyridin-2-ylidene chelates, namely, f-ct6a‒c, are synthesized, and their structures and photophysical properties are comprehensively investigated. Moreover, these emitters can undergo interconversion in refluxing 1,2,4-trichlorobenzene, catalyzed by a mixture of sodium acetate (NaOAc) and p-toluenesulfonic acid monohydrate (TsOH·H2O) without decomposition. All Ir(III) complexes present good photoluminescence quantum yield (ΦPL = 83-88%) with peak maximum (max.) at 443-452 nm and narrowed full width at half maximum (FWHM = 66-73 nm). Among all the fabricated OLED devices, f-ct6b delivers a max. external quantum efficiency (EQE) of 23.4% and Commission Internationale de L'Eclairage CIEx , y coordinates of (0.14, 0.12), whereas the hyper-OLED device based on f-ct6a and 5H,9H,11H,15H-[1,4] benzazaborino [2,3,4-kl][1,4]benzazaborino[4',3',2':4,5][1,4]benzazaborino[3,2-b]phenazaborine-7,13-diamine, N7,N7,N13,N13,5,9,11,15-octaphenyl (ν-DABNA) exhibits max. EQE of 26.2% and CIEx , y of (0.12, 0.13). Finally, the corresponding tandem OLED with f-ct6b as dopant gives a max. luminance of over 10 000 cd m-2 and max. EQE of 42.1%, confirming their candidacies for making true-blue OLEDs.
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Affiliation(s)
- Jie Yan
- Department of Materials Sciences and Engineering, City University of Hong Kong, Hong Kong, Hong Kong SAR, 999077, China
| | - Zi-Qi Feng
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, 215123, China
| | - Yixin Wu
- Department of Materials Sciences and Engineering, City University of Hong Kong, Hong Kong, Hong Kong SAR, 999077, China
| | - Dong-Ying Zhou
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, 215123, China
| | - Shek-Man Yiu
- Department of Chemistry and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, Hong Kong SAR, 999077, China
| | - Chin-Yiu Chan
- Department of Materials Sciences and Engineering, City University of Hong Kong, Hong Kong, Hong Kong SAR, 999077, China
| | - Yi Pan
- Department of Chemistry and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, Hong Kong SAR, 999077, China
| | - Kai Chung Lau
- Department of Chemistry and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, Hong Kong SAR, 999077, China
| | - Liang-Sheng Liao
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, 215123, China
| | - Yun Chi
- Department of Materials Sciences and Engineering, City University of Hong Kong, Hong Kong, Hong Kong SAR, 999077, China
- Department of Chemistry and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, Hong Kong SAR, 999077, China
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6
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Lebedeva IV, Jornet-Somoza J. Optical properties and exciton transfer between N-heterocyclic carbene iridium(III) complexes for blue light-emitting diode applications from first principles. J Chem Phys 2024; 160:084107. [PMID: 38391015 DOI: 10.1063/5.0193161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 02/05/2024] [Indexed: 02/24/2024] Open
Abstract
N-heterocyclic carbene (NHC) iridium(III) complexes are considered as promising candidates for blue emitters in organic light-emitting diodes. They can play the roles of the emitter as well as of electron and hole transporters in the same emission layer. We investigate optical transitions in such complexes with account of geometry and electronic structure changes upon excitation or charging and exciton transfer between the complexes from first principles. It is shown that excitation of NHC iridium complexes is accompanied by a large reorganization energy ∼0.7 eV and a significant loss in the oscillator strength, which should lead to low exciton diffusion. Calculations with account of spin-orbit coupling reveal a small singlet-triplet splitting ∼0.1 eV, whereas the oscillator strength for triplet excitations is found to be an order of magnitude smaller than for the singlet ones. The contributions of the Förster and Dexter mechanisms are analyzed via the explicit integration of transition densities. It is shown that for typical distances between emitter complexes in the emission layer, the contribution of the Dexter mechanism should be negligible compared to the Förster mechanism. At the same time, the ideal dipole approximation, although giving the correct order of the exciton coupling, fails to reproduce the result taking into account spatial distribution of the transition density. For charged NHC complexes, we find a number of optical transitions close to the emission peak of the blue emitter with high exciton transfer rates that can be responsible for exciton-polaron quenching. The nature of these transitions is analyzed.
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Affiliation(s)
- Irina V Lebedeva
- Nano-Bio Spectroscopy Group and ETSF, Universidad del País Vasco, CFM CSIC-UPV/EHU, 20018 San Sebastián, Spain
| | - Joaquim Jornet-Somoza
- Nano-Bio Spectroscopy Group and ETSF, Universidad del País Vasco, CFM CSIC-UPV/EHU, 20018 San Sebastián, Spain
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany
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Mamada M, Hayakawa M, Ochi J, Hatakeyama T. Organoboron-based multiple-resonance emitters: synthesis, structure-property correlations, and prospects. Chem Soc Rev 2024; 53:1624-1692. [PMID: 38168795 DOI: 10.1039/d3cs00837a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Boron-based multiple-resonance (MR) emitters exhibit the advantages of narrowband emission, high absolute photoluminescence quantum yield, thermally activated delayed fluorescence (TADF), and sufficient stability during the operation of organic light-emitting diodes (OLEDs). Thus, such MR emitters have been widely applied as blue emitters in triplet-triplet-annihilation-driven fluorescent devices used in smartphones and televisions. Moreover, they hold great promise as TADF or terminal emitters in TADF-assisted fluorescence or phosphor-sensitised fluorescent OLEDs. Herein we comprehensively review organoboron-based MR emitters based on their synthetic strategies, clarify structure-photophysical property correlations, and provide design guidelines and future development prospects.
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Affiliation(s)
- Masashi Mamada
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Masahiro Hayakawa
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Junki Ochi
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Takuji Hatakeyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
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Yan J, Qu ZH, Zhou DY, Yiu SM, Qin Y, Zhou X, Liao LS, Chi Y. Bis-tridentate Ir(III) Phosphors and Blue Hyperphosphorescence with Suppressed Efficiency Roll-Off at High Brightness. ACS APPLIED MATERIALS & INTERFACES 2024; 16:3809-3818. [PMID: 38211320 DOI: 10.1021/acsami.3c16260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
Narrowband blue emitters are indispensable in achieving ultrahigh-definition OLED displays that satisfy the stringent BT 2020 standard. Hereby, a series of bis-tridentate Ir(III) complexes bearing electron-deficient imidazo[4,5-b]pyridin-2-ylidene carbene coordination fragments and 2,6-diaryloxy pyridine ancillary groups were designed and synthesized. They exhibited deep blue emission with quantum yields of up to 89% and a radiative lifetime of 0.71 μs in the DPEPO host matrix, indicating both the high efficiency and excellent energy transfer process from the host to dopant. The OLED based on Irtb1 showed an emission at 468 nm with a maximum external quantum efficiency (EQE) of 22.7%. Moreover, the hyper-OLED with Irtb1 as a sensitizer for transferring energy to terminal emitter v-DABNA exhibited a narrowband blue emission at 472 nm and full width at half-maximum (FWHM) of 24 nm, a maximum EQE of 23.5%, and EQEs of 19.7, 16.1, and 12.9% at a practical brightness of 100, 1000, and 5000 cd/m2, respectively.
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Affiliation(s)
- Jie Yan
- Department of Chemistry, Department of Materials Science and Engineering, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon 999077, Hong Kong
| | - Zhi-Hao Qu
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215006, China
| | - Dong-Ying Zhou
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215006, China
| | - Shek-Man Yiu
- Department of Chemistry, Department of Materials Science and Engineering, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon 999077, Hong Kong
| | - Yanyan Qin
- Department of Chemistry, Department of Materials Science and Engineering, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon 999077, Hong Kong
| | - Xiuwen Zhou
- School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Liang-Sheng Liao
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215006, China
| | - Yun Chi
- Department of Chemistry, Department of Materials Science and Engineering, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon 999077, Hong Kong
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Yan J, Wu C, Tong KN, Zhou F, Chen Y, Pan Y, Xie G, Chi Y, Lau KC, Wei G. Structural Engineering of Iridium(III) Phosphors with Imidazo[4,5-b]pyrazin-2-ylidene Cyclometalates for Efficient Blue Electroluminescence. SMALL METHODS 2024:e2301555. [PMID: 38185747 DOI: 10.1002/smtd.202301555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 12/27/2023] [Indexed: 01/09/2024]
Abstract
Iridium(III) complexes are particularly noted for their excellent potentials in fabrication of blue organic light-emitting diodes (OLEDs), but the severe efficiency roll-off largely hampered their practical applications. To reveal the underlying characteristics, three Ir(III) complexes, namely f-ct5c, f-ct5d, and f-ct11, bearing imidazo[4,5-b]pyrazin-2-ylidene cyclometalates are prepared and characterized in detail. Both f-ct5c and f-ct5d (also their mixture f-ct5mix) gave intensive blue emissions peaking at ≈465 nm with short radiative lifetimes of 1.76 and 2.45 µs respectively, in degassed toluene. Alternatively, f-ct11 with two 4-tert-butylphenyl substituents on each imidazo[4,5-b]pyrazin-2-ylidene entity, possessed a bluish-green emission (508 nm) together with an extended radiative lifetime of 34.3 µs in the dispersed PMMA matrix. Consequently, the resulting solution-processed OLED with f-ct11 delivered a maximum external quantum efficiency (EQEmax ) of 6.5% with serious efficiency roll-offs. In contrast, f-ct5mix based device achieved a high EQEmax of 27.2% and the EQE maintained at 23.0% of 1000 cd m-2 . Furthermore, the hyper-OLEDs with f-ct5mix as the sensitizer and v-DABNA as the terminal emitter afford narrowed emission with a considerably high EQEmax exceeding 32%, affirming the potential of f-ct5mix to serve as both the emitter and sensitizer in OLEDs.
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Affiliation(s)
- Jie Yan
- Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, 999077, HONG KONG
| | - Chengcheng Wu
- Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, China
| | - Kai-Ning Tong
- Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, China
| | - Fan Zhou
- Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, 999077, HONG KONG
| | - Yidong Chen
- Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, 999077, HONG KONG
| | - Yi Pan
- Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, 999077, HONG KONG
| | - Guohua Xie
- The Institute of Flexible Electronics (Future Technologies), Xiamen University, Xiamen, 361005, China
| | - Yun Chi
- Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, 999077, HONG KONG
| | - Kai-Chung Lau
- Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, 999077, HONG KONG
| | - Guodan Wei
- Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, China
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10
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Yang X, Waterhouse GIN, Lu S, Yu J. Recent advances in the design of afterglow materials: mechanisms, structural regulation strategies and applications. Chem Soc Rev 2023; 52:8005-8058. [PMID: 37880991 DOI: 10.1039/d2cs00993e] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2023]
Abstract
Afterglow materials are attracting widespread attention owing to their distinctive and long-lived optical emission properties which create exciting opportunities in various fields. Recent research has led to the discovery of many new afterglow materials featuring high photoluminescence quantum yields (PLQY) and lifetimes of up to several hours under ambient conditions. Afterglow materials are typically categorized according to their luminescence mechanism, such as long-persistent luminescence (LPL), room temperature phosphorescence (RTP), or thermally activated delayed fluorescence (TADF). Through rational design and novel synthetic strategies to modulate spin-orbit coupling (SOC) and populate triplet exciton states (T1), luminophores with long lifetimes and bright afterglow characteristics can be realized. Initial research towards afterglow materials focused mainly on pure inorganic materials, many of which possessed inherent disadvantages such as metal toxicity or low energy emissions. In recent years, organic-inorganic hybrid afterglow materials (OIHAMs) have been developed with high PLQY and long lifetimes. These hybrid materials exploit the tunable structure and easy processing of organic molecules, as well as enhanced SOC and intersystem crossing (ISC) processes involving heavy atom dopants, to achieve excellent afterglow performance. In this review, we begin by briefly discussing the structure and composition of inorganic and organic-inorganic hybrid afterglow materials, including strategies for regulating their lifetime, PLQY and luminescence wavelength. The specific advantages of organic-inorganic hybrid afterglow materials, including low manufacturing costs, diverse molecular/electronic structures, tunable structures and optical properties, and compatibility with a variety of substrates, are emphasized. Subsequently, we discuss in detail the fundamental mechanisms used by afterglow materials, their classification, design principles, and end applications (including sensing, anticounterfeiting, and photoelectric devices, among others). Finally, existing challenges and promising future directions are discussed, laying a platform for the design of afterglow materials for specific applications.
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Affiliation(s)
- Xin Yang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, China.
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou 450001, China.
- International Center of Future Science, Jilin University, Changchun 130012, China
| | | | - Siyu Lu
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou 450001, China.
| | - Jihong Yu
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, China.
- International Center of Future Science, Jilin University, Changchun 130012, China
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11
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Wu C, Tong K, Shi K, Jin Z, Wu Y, Mu Y, Huo Y, Tang M, Yang C, Meng H, Kang F, Wei G. New [3+2+1] Iridium Complexes as Effective Phosphorescent Sensitizers for Efficient Narrowband Saturated-Blue Hyper-OLEDs. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2301112. [PMID: 37653609 PMCID: PMC10582407 DOI: 10.1002/advs.202301112] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/23/2023] [Indexed: 09/02/2023]
Abstract
Two newly designed and synthesized [3+2+1] iridium complexes through introducing bulky trimethylsiliyl (TMS) groups are doped with a terminal emitter of v-DABNA to form an coincident overlapping spectra between the emission of these two phosphors and the absorption of v-DABNA, creating cascade resonant energy transfer for efficient triplet harvesting. To boost the color quality and efficiency, the fabricated hyper-OLEDs have been optimized to achieve a high external quantum efficiency of 31.06%, which has been among the highest efficiency results reported for phosphor sensitized saturated-blue hyper-OLEDs, and pure blue emission peak at 467 nm with the full width at half maxima (FWHM) as narrow as 18 nm and the CIEy values down to 0.097, satisfying the National Institute of Standards and Technology (NIST) requirement for saturated blue OLEDs display. Surprisingly, such hyper-OLEDs have obtained the converted lifetime (LT50 ) up to 4552 h at the brightness of 100 cd m-2 , demonstrating effective Förster resonance energy transfer (FRET) process. Therefore, employing these new bulky TMS substituent [3+2+1] iridium(III) complexes for effective sensitizers can greatly pave the way for further development of high efficiency and stable blue OLEDs in display and lighting applications.
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Affiliation(s)
- Chengcheng Wu
- Tsinghua–Berkeley Shenzhen Institute (TBSI)Tsinghua UniversityShenzhen518055China
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| | - Kai‐Ning Tong
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| | - Kefei Shi
- Tsinghua–Berkeley Shenzhen Institute (TBSI)Tsinghua UniversityShenzhen518055China
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| | - Zhaoyun Jin
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| | - Yuan Wu
- PURI Materials, IncShenzhen518133China
| | - Yingxiao Mu
- School of Chemical Engineering and Light IndustryGuangdong University of TechnologyGuangzhou510006China
| | - Yanping Huo
- School of Chemical Engineering and Light IndustryGuangdong University of TechnologyGuangzhou510006China
| | - Man‐Chung Tang
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| | - Chen Yang
- PURI Materials, IncShenzhen518133China
| | - Hong Meng
- School of Advanced MaterialsShenzhen Graduate SchoolPeking UniversityShenzhen518055China
| | - Feiyu Kang
- Tsinghua–Berkeley Shenzhen Institute (TBSI)Tsinghua UniversityShenzhen518055China
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| | - Guodan Wei
- Tsinghua–Berkeley Shenzhen Institute (TBSI)Tsinghua UniversityShenzhen518055China
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
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12
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Yan J, Wang SF, Hsu CH, Shi EHC, Wu CC, Chou PT, Yiu SM, Chi Y, You C, Peng IC, Hung WY. Engineering of Cyano Functionalized Benzo[ d]imidazol-2-ylidene Ir(III) Phosphors for Blue Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2023; 15:21333-21343. [PMID: 37074734 DOI: 10.1021/acsami.3c02671] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In this study, we designed and synthesized three series of blue emitting homoleptic iridium(III) phosphors bearing 4-cyano-3-methyl-1-phenyl-6-(trifluoromethyl)-benzo[d]imidazol-2-ylidene (mfcp), 5-cyano-1-methyl-3-phenyl-6-(trifluoromethyl)-benzo[d]imidazol-2-ylidene (ofcp), and 1-(3-(tert-butyl)phenyl)-6-cyano-3-methyl-4-(trifluoromethyl)-benzo[d]imidazol-2-ylidene (5-mfcp) cyclometalates, respectively. These iridium complexes exhibit intense phosphorescence in the high energy region of 435-513 nm in the solution state at RT, to which the relatively large T1 → S0 transition dipole moment is beneficial for serving as a pure emitter and an energy donor to the multiresonance thermally activated delayed fluorescence (MR-TADF) terminal emitters via Förster resonance energy transfer (FRET). The resulting OLEDs achieved true blue, narrow bandwidth EL with a max EQE of 16-19% and great suppression of efficiency roll-off with ν-DABNA and t-DABNA. We obtained the FRET efficiency up to 85% using titled Ir(III) phosphors f-Ir(mfcp)3 and f-Ir(5-mfcp)3 to achieve true blue narrow bandwidth emission. Importantly, we also provide analysis on the kinetic parameters involved in the energy transfer processes and, accordingly, propose feasible ways to improve the efficiency roll-off caused by the shortened radiative lifetime of hyperphosphorescence.
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Affiliation(s)
- Jie Yan
- Department of Materials Sciences and Engineering, Department of Chemistry, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon Tong 999077 Hong Kong SAR, China
| | - Sheng Fu Wang
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Chao-Hsien Hsu
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Emily Hsue-Chi Shi
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Chi-Chi Wu
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Pi-Tai Chou
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Shek-Man Yiu
- Department of Materials Sciences and Engineering, Department of Chemistry, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon Tong 999077 Hong Kong SAR, China
| | - Yun Chi
- Department of Materials Sciences and Engineering, Department of Chemistry, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon Tong 999077 Hong Kong SAR, China
| | - Caifa You
- Department of Materials Sciences and Engineering, Department of Chemistry, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon Tong 999077 Hong Kong SAR, China
| | - I-Che Peng
- Department of Optoelectronics and Materials Technology, National Taiwan Ocean University, Keelung 20224, Taiwan
| | - Wen-Yi Hung
- Department of Optoelectronics and Materials Technology, National Taiwan Ocean University, Keelung 20224, Taiwan
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13
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Kim E, Park J, Jun M, Shin H, Baek J, Kim T, Kim S, Lee J, Ahn H, Sun J, Ko SB, Hwang SH, Lee JY, Chu C, Kim S. Highly efficient and stable deep-blue organic light-emitting diode using phosphor-sensitized thermally activated delayed fluorescence. SCIENCE ADVANCES 2022; 8:eabq1641. [PMID: 36240272 PMCID: PMC9565789 DOI: 10.1126/sciadv.abq1641] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 08/29/2022] [Indexed: 06/16/2023]
Abstract
Phosphorescent and thermally activated delayed fluorescence (TADF) blue organic light-emitting diodes (OLEDs) have been developed to overcome the low efficiency of fluorescent OLEDs. However, device instability, originating from triplet excitons and polarons, limits blue OLED applications. Here, we develop a phosphor-sensitized TADF emission system with TADF emitters to achieve high efficiency and long operational lifetime. Peripheral carbazole moieties are introduced in conventional multi-resonance-type emitters containing one boron atom. The triplet exciton density of the TADF emitter is reduced by facilitating reverse intersystem crossing, and the Förster resonant energy transfer rate from phosphor sensitizer is enhanced by high absorption coefficient of the emitters. The emitter exhibited an operational lifetime of 72.9 hours with Commission Internationale de L'Eclairage chromaticity coordinate y = 0.165, which was 6.6 times longer than those of devices using conventional TADF emitters.
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Affiliation(s)
- Eungdo Kim
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Junha Park
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Mieun Jun
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Hyosup Shin
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Jangyeol Baek
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Taeil Kim
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Seran Kim
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Jiyoung Lee
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Heechoon Ahn
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Jinwon Sun
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Soo-Byung Ko
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Seok-Hwan Hwang
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Jun Yeob Lee
- School of Chemical Engineering, Sungkyunkwan University, Suwon, Gyeonggi 16419, Republic of Korea
| | - Changwoong Chu
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
| | - Sunghan Kim
- Materials Research Team, Display Research Center, Samsung Display, Giheung, Gyeonggi 17113, Republic of Korea
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14
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Yang X, Zhou X, Zhang Y, Li D, Li C, You C, Chou T, Su S, Chou P, Chi Y. Blue Phosphorescence and Hyperluminescence Generated from Imidazo[4,5-b]pyridin-2-ylidene-Based Iridium(III) Phosphors. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2201150. [PMID: 35822668 PMCID: PMC9443441 DOI: 10.1002/advs.202201150] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 06/02/2022] [Indexed: 05/19/2023]
Abstract
Four isomeric, homoleptic iridium(III) metal complexes bearing 5-(trifluoromethyl)imidazo[4,5-b]pyridin-2-ylidene and 6-(trifluoromethyl)imidazo[4,5-b]pyridin-2-ylidene-based cyclometalating chelates are successfully synthesized. The meridional isomers can be converted to facial isomers through acid induced isomerization. The m-isomers display a relatively broadened and red-shifted emission, while f-isomers exhibit narrowed blue emission band, together with higher photoluminescent quantum yields and reduced radiative lifetime relative to the mer-counterparts. Maximum external quantum efficiencies of 13.5% and 22.8% are achieved for the electrophosphorescent devices based on f-tpb1 and m-tpb1 as dopant emitter together with CIE coordinates of (0.15, 0.23) and (0.22, 0.45), respectively. By using f-tpb1 as the sensitizing phosphor and t-DABNA as thermally activated delayed fluorescence (TADF) terminal emitter, hyperluminescent OLEDs are successfully fabricated, giving high efficiency of 29.6%, full width at half maximum (FWHM) of 30 nm, and CIE coordinates of (0.13, 0.11), confirming the efficient Förster resonance energy transfer (FRET) process.
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Affiliation(s)
- Xilin Yang
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and DevicesSouth China University of TechnologyGuangzhou510640China
| | - Xiuwen Zhou
- School of Mathematics and PhysicsThe University of QueenslandBrisbaneQueensland4072Australia
| | - Ye‐Xin Zhang
- Suzhou Joysun Advanced Materials Co., Ltd. SuzhouJiangsu215126China
| | - Deli Li
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and DevicesSouth China University of TechnologyGuangzhou510640China
| | - Chensen Li
- Department of ChemistryDepartment of Materials Sciences and Engineeringand Center of Super‐Diamond and Advanced Films (COSDAF)City University of Hong KongHong Kong SAR999077China
| | - Caifa You
- Department of ChemistryDepartment of Materials Sciences and Engineeringand Center of Super‐Diamond and Advanced Films (COSDAF)City University of Hong KongHong Kong SAR999077China
| | - Tai‐Che Chou
- Department of ChemistryNational Taiwan UniversityTaipei10617Taiwan
| | - Shi‐Jian Su
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and DevicesSouth China University of TechnologyGuangzhou510640China
| | - Pi‐Tai Chou
- Department of ChemistryNational Taiwan UniversityTaipei10617Taiwan
| | - Yun Chi
- Department of ChemistryDepartment of Materials Sciences and Engineeringand Center of Super‐Diamond and Advanced Films (COSDAF)City University of Hong KongHong Kong SAR999077China
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15
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Zou Y, Hu J, Yu M, Miao J, Xie Z, Qiu Y, Cao X, Yang C. High-Performance Narrowband Pure-Red OLEDs with External Quantum Efficiencies up to 36.1% and Ultralow Efficiency Roll-Off. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2201442. [PMID: 35588162 DOI: 10.1002/adma.202201442] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 04/28/2022] [Indexed: 06/15/2023]
Abstract
High-color-purity blue and green organic light-emitting diodes (OLEDs) have been resolved thanks to the development of B/N-based polycyclic multiple resonance (MR) emitters. However, due to the derivatization limit of B/N polycyclic structures, the design of red MR emitters remains challenging. Herein, a series of novel red MR emitters is reported by para-positioning N-π-N, O-π-O, B-π-B pairs onto a benzene ring to construct an MR central core. These emitters can be facilely and modularly synthesized, allowing for easy fine-tuning of emission spectra by peripheral groups. Moreover, these red MR emitters display excellent photophysical properties such as near-unity photoluminescence quantum yield (PLQY), fast radiative decay rate (kr ) up to 7.4 × 107 s-1 , and most importantly, narrowband emission with full-width at half-maximum (FWHM) of 32 nm. Incorporating these MR emitters, pure red OLEDs sensitized by phosphor realize state-of-the-art device performances with external quantum efficiency (EQE) exceeding 36%, ultralow efficiency roll-off (EQE remains as high as 25.1% at the brightness of 50 000 cd m-2 ), ultrahigh brightness over 130 000 cd m-2 , together with good device lifetime.
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Affiliation(s)
- Yang Zou
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Jiahao Hu
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Mingxin Yu
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Jingsheng Miao
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Ziyang Xie
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Yuntao Qiu
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Xiaosong Cao
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Chuluo Yang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
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16
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Lin KH, Wetzelaer GJAH, Blom PWM, Andrienko D. Virtual Screening of TADF Emitters for Single-Layer OLEDs. Front Chem 2022; 9:800027. [PMID: 34976956 PMCID: PMC8716429 DOI: 10.3389/fchem.2021.800027] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 11/17/2021] [Indexed: 11/13/2022] Open
Abstract
Thermally-activated delayed fluorescence (TADF) is a concept which helps to harvest triplet excitations, boosting the efficiency of an organic light-emitting diode. TADF can be observed in molecules with spatially separated donor and acceptor groups with a reduced triplet-singlet energy level splitting. TADF materials with balanced electron and hole transport are attractive for realizing efficient single-layer organic light emitting diodes, greatly simplifying their manufacturing and improving their stability. Our goal here is to computationally screen such materials and provide a comprehensive database of compounds with a range of emission wavelengths, ionization energies, and electron affinities.
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Affiliation(s)
- Kun-Han Lin
- Max Planck Institute for Polymer Research, Mainz, Germany
| | | | - Paul W M Blom
- Max Planck Institute for Polymer Research, Mainz, Germany
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17
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You C, Wang XQ, Zhou X, Yuan Y, Liao LS, Liao YC, Chou PT, Chi Y. Homoleptic Ir(III) Phosphors with 2-Phenyl-1,2,4-triazol-3-ylidene Chelates for Efficient Blue Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2021; 13:59023-59034. [PMID: 34865484 DOI: 10.1021/acsami.1c17308] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In this report, we synthesized two series of deep-blue-emitting homoleptic iridium(III) phosphors bearing 1,2,4-triazol-3-ylidene and 5-(trifluoromethyl)-1,2,4-triazol-3-ylidene cyclometalate. Compared with reported synthetic routes using Ag2O as the promoter, herein, we adopted a different strategy to furnish these complexes in high yields. Also, the meridional to facial isomerization was executed in the presence of trifluoroacetic acid. These phosphors were examined using NMR spectroscopies, single-crystal X-ray diffraction studies, and photophysical methods. The results revealed that electron-withdrawing trifluoromethyl substitution on the N-heterocyclic carbene fragment only gave a minor variation of photoluminescence peak wavelengths and a decrease in radiative lifetime but notable reduction in thermal stabilities. The parent 1,2,4-triazol-3-ylidene complexes have been demonstrated to be suitable for use as deep-blue phosphors, with structured emission with the peak max. located at ∼420 nm and with photoluminescence quantum yields in a range of 34.8-42.5% in degassed THF solution at RT. Fabrication of both the phosphorescent organic light-emitting diodes (OLEDs) and phosphor-sensitized OLEDs (or hyperphosphorescence) was successfully conducted, from which the OLED device based on m-tz1 showed a max. external quantum efficiency (EQE) of 10% with CIEx,y coordinates of 0.15, 0.06, while the corresponding hyperphosphorescent OLED using m-tz2 as a sensitizer and t-DABNA as a terminal emitter afforded a significantly improved max. EQE of 19.7%, EL λmax of 468 nm, and FWHM of 31 nm with CIEx,y coordinates of 0.12, 0.13.
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Affiliation(s)
- Caifa You
- Department of Materials Sciences and Engineering, Department of Chemistry, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon Tong, Kowloon 999077, Hong Kong SAR, China
| | - Xue-Qi Wang
- Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123, China
| | - Xiuwen Zhou
- School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Yi Yuan
- Department of Materials Sciences and Engineering, Department of Chemistry, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon Tong, Kowloon 999077, Hong Kong SAR, China
| | - Liang-Sheng Liao
- Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123, China
| | - Yu-Chan Liao
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Pi-Tai Chou
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Yun Chi
- Department of Materials Sciences and Engineering, Department of Chemistry, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon Tong, Kowloon 999077, Hong Kong SAR, China
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18
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Polgar AM, Hudson ZM. Thermally activated delayed fluorescence materials as organic photosensitizers. Chem Commun (Camb) 2021; 57:10675-10688. [PMID: 34569578 DOI: 10.1039/d1cc04593h] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Photosensitizer molecules play a crucial role in materials and life sciences. Efforts to improve their performance and reduce the associated costs are therefore vital for advancing environmentally friendly light-driven technologies. In this Feature Article, we describe the use of photosensitizers that make use of thermally activated delayed fluorescence (TADF), their benefits compared to conventional fluorescent and phosphorescent sensitizers, and the efforts of our group and others to develop emitters with application-tailored properties. The key feature is the diversity of accessible excited state pathways, which may be tuned by molecular and supramolecular approaches to suit a particular problem. This unique property has allowed TADF emitters to become competitive for applications including TADF-sensitized fluorescence in light emitting diodes and chemical sensing, organic long persistent luminescence, photodynamic therapy, and non-coherent photon upconversion.
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Affiliation(s)
- Alexander M Polgar
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada.
| | - Zachary M Hudson
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada.
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19
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Poisson J, Polgar AM, Fromel M, Pester CW, Hudson ZM. Preparation of Patterned and Multilayer Thin Films for Organic Electronics via Oxygen‐Tolerant SI‐PET‐RAFT. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202107830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Jade Poisson
- Department of Chemistry The University of British Columbia 2036 Main Mall Vancouver British Columbia V6T 1Z1 Canada
| | - Alexander M. Polgar
- Department of Chemistry The University of British Columbia 2036 Main Mall Vancouver British Columbia V6T 1Z1 Canada
| | - Michele Fromel
- Department of Chemical Engineering Department of Chemistry Department of Materials Science and Engineering The Pennsylvania State University University Park PA 16802 USA
| | - Christian W. Pester
- Department of Chemical Engineering Department of Chemistry Department of Materials Science and Engineering The Pennsylvania State University University Park PA 16802 USA
| | - Zachary M. Hudson
- Department of Chemistry The University of British Columbia 2036 Main Mall Vancouver British Columbia V6T 1Z1 Canada
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20
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Nam S, Kim JW, Bae HJ, Maruyama YM, Jeong D, Kim J, Kim JS, Son W, Jeong H, Lee J, Ihn S, Choi H. Improved Efficiency and Lifetime of Deep-Blue Hyperfluorescent Organic Light-Emitting Diode using Pt(II) Complex as Phosphorescent Sensitizer. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2100586. [PMID: 34137208 PMCID: PMC8373157 DOI: 10.1002/advs.202100586] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/20/2021] [Indexed: 05/19/2023]
Abstract
Although the organic light-emitting diode (OLED) has been successfully commercialized, the development of deep-blue OLEDs with high efficiency and long lifetime remains a challenge. Here, a novel hyperfluorescent OLED that incorporates the Pt(II) complex (PtON7-dtb) as a phosphorescent sensitizer and a hydrocarbon-based and multiple resonance-based fluorophore as an emitter (TBPDP and ν-DABNA) in the device emissive layer (EML), is proposed. Such an EML system can promote efficient energy transfer from the triplet excited states of the sensitizer to the singlet excited states of the fluorophore, thus significantly improving the efficiency and lifetime of the device. As a result, a deep-blue hyperfluorescent OLED using a multiple resonance-based fluorophore (ν-DABNA) with Commission Internationale de L'Eclairage chromaticity coordinate y below 0.1 is demonstrated, which attains a narrow full width at half maximum of ≈17 nm, fourfold increased maximum current efficiency of 48.9 cd A-1 , and 19-fold improved half-lifetime of 253.8 h at 1000 cd m-2 compared to a conventional phosphorescent OLED. The findings can lead to better understanding of the hyperfluorescent OLEDs with high performance.
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Affiliation(s)
- Sungho Nam
- Samsung Advanced Institute of TechnologySamsung Electronics Co., Ltd.130 Samsung‐roSuwon‐siGyeonggi‐do16678Republic of Korea
| | - Ji Whan Kim
- Samsung Advanced Institute of TechnologySamsung Electronics Co., Ltd.130 Samsung‐roSuwon‐siGyeonggi‐do16678Republic of Korea
| | - Hye Jin Bae
- Samsung Advanced Institute of TechnologySamsung Electronics Co., Ltd.130 Samsung‐roSuwon‐siGyeonggi‐do16678Republic of Korea
| | - Yusuke Makida Maruyama
- Samsung Advanced Institute of TechnologySamsung Electronics Co., Ltd.130 Samsung‐roSuwon‐siGyeonggi‐do16678Republic of Korea
| | - Daun Jeong
- Data and Information Technology CenterSamsung Electronics Co., Ltd.1 Samsungjeonja‐roHwaseong‐siGyeonggi‐do18448Republic of Korea
| | - Joonghyuk Kim
- Samsung Advanced Institute of TechnologySamsung Electronics Co., Ltd.130 Samsung‐roSuwon‐siGyeonggi‐do16678Republic of Korea
| | - Jong Soo Kim
- Samsung Advanced Institute of TechnologySamsung Electronics Co., Ltd.130 Samsung‐roSuwon‐siGyeonggi‐do16678Republic of Korea
| | - Won‐Joon Son
- Data and Information Technology CenterSamsung Electronics Co., Ltd.1 Samsungjeonja‐roHwaseong‐siGyeonggi‐do18448Republic of Korea
| | - Hyein Jeong
- Display Research CenterSamsung Display Co.1 Samsung‐roYongin‐siGyeonggi‐do17113Republic of Korea
| | - Jaesang Lee
- Department of Electrical and Computer EngineeringInter‐University Semiconductor Research CenterSeoul National UniversitySeoul08826Republic of Korea
| | - Soo‐Ghang Ihn
- Samsung Advanced Institute of TechnologySamsung Electronics Co., Ltd.130 Samsung‐roSuwon‐siGyeonggi‐do16678Republic of Korea
| | - Hyeonho Choi
- Samsung Advanced Institute of TechnologySamsung Electronics Co., Ltd.130 Samsung‐roSuwon‐siGyeonggi‐do16678Republic of Korea
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21
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Poisson J, Polgar AM, Fromel M, Pester CW, Hudson ZM. Preparation of Patterned and Multilayer Thin Films for Organic Electronics via Oxygen-Tolerant SI-PET-RAFT. Angew Chem Int Ed Engl 2021; 60:19988-19996. [PMID: 34337845 DOI: 10.1002/anie.202107830] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Indexed: 11/10/2022]
Abstract
An oxygen-tolerant approach is described for preparing surface-tethered polymer films of organic semiconductors directly from electrode substrates using polymer brush photolithography. A photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) approach was used to prepare multiblock polymer architectures with the structures of multi-layer organic light-emitting diodes (OLEDs), including electron-transport, emissive, and hole-transport layers. The preparation of thermally activated delayed fluorescence (TADF) and thermally assisted fluorescence (TAF) trilayer OLED architectures are described. By using direct photomasking as well as a digital micromirror device, we also show that the surface-initiated (SI)-PET-RAFT approach allows for enhanced control over layer thickness, and spatial resolution in polymer brush patterning at low cost.
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Affiliation(s)
- Jade Poisson
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
| | - Alexander M Polgar
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
| | - Michele Fromel
- Department of Chemical Engineering, Department of Chemistry, Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Christian W Pester
- Department of Chemical Engineering, Department of Chemistry, Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Zachary M Hudson
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
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22
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Wang J, Liang B, Wei J, Li Z, Xu Y, Yang T, Li C, Wang Y. Highly Efficient Electrofluorescence Material Based on Pure Organic Phosphor Sensitization**. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202104755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Jiaxuan Wang
- State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Baoyan Liang
- Jihua Laboratory 28 Huandao South Road Foshan 528200 Guangdong Province P. R. China
| | - Jinbei Wei
- State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Zhiqiang Li
- Jihua Laboratory 28 Huandao South Road Foshan 528200 Guangdong Province P. R. China
| | - Yincai Xu
- State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Tong Yang
- State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Chenglong Li
- State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Yue Wang
- State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University Changchun 130012 P. R. China
- Jihua Laboratory 28 Huandao South Road Foshan 528200 Guangdong Province P. R. China
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23
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Wang J, Liang B, Wei J, Li Z, Xu Y, Yang T, Li C, Wang Y. Highly Efficient Electrofluorescence Material Based on Pure Organic Phosphor Sensitization*. Angew Chem Int Ed Engl 2021; 60:15335-15339. [PMID: 33904242 DOI: 10.1002/anie.202104755] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Indexed: 11/07/2022]
Abstract
Pure organic room-temperature phosphorescence (RTP) materials are considered as potential candidates for replacing precious metal complexes to fabricate highly efficient organic light-emitting devices (OLEDs). However, applications of the reported RTP materials in OLEDs are seriously impeded by their low photoluminescence quantum yields (PLQYs) in a thin film state. To overcome these obstacles, we established a new strategy to construct highly efficient OLEDs based on a pure organic RTP material sensitized fluorescence emitter by selecting benzimidazole-triazine molecules (PIM-TRZ), 2,6-di(phenothiazinyl)naphthalene (β-DPTZN), and 5,6,11,12-tetraphenylnaphthacene (rubrene) as host, phosphor sensitizer, and fluorescent emitter, respectively. The perfect combination of host, phosphorescent sensitizer, and fluorescent emitter in the emitting layer ensure the outstanding performance of the devices with an external quantum efficiency (EQE) of 15.7 %.
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Affiliation(s)
- Jiaxuan Wang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Baoyan Liang
- Jihua Laboratory, 28 Huandao South Road, Foshan, 528200, Guangdong Province, P. R. China
| | - Jinbei Wei
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Zhiqiang Li
- Jihua Laboratory, 28 Huandao South Road, Foshan, 528200, Guangdong Province, P. R. China
| | - Yincai Xu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Tong Yang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Chenglong Li
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Yue Wang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.,Jihua Laboratory, 28 Huandao South Road, Foshan, 528200, Guangdong Province, P. R. China
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24
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Haase N, Danos A, Pflumm C, Stachelek P, Brütting W, Monkman AP. Are the rates of dexter transfer in TADF hyperfluorescence systems optically accessible? MATERIALS HORIZONS 2021; 8:1805-1815. [PMID: 34846509 DOI: 10.1039/d0mh01666g] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Seemingly not, but for unexpected reasons. Combining the triplet harvesting properties of TADF materials with the fast emission rates and colour purity of fluorescent emitters is attractive for developing high performance OLEDs. In this "hyperfluorescence" approach, triplet excitons are converted to singlets on the TADF material and transferred to the fluorescent material by long range Förster energy transfer. The primary loss mechanism is assumed to be Dexter energy transfer from the TADF triplet to the non-emissive triplet of the fluorescent emitter. Here we use optical spectroscopy to investigate energy transfer in representative emissive layers. Despite observing kinetics that at first appear consistent with Dexter quenching of the TADF triplet state, transient absorption, photoluminescence quantum yields, and comparison to phosphor-sensitised "hyperphosphorescent" systems reveal that this is not the case. While Dexter quenching by the fluorescent emitter is likely still a key loss mechanism in devices, we demonstrate that - despite initial appearances - it is inoperative under optical excitation. These results reveal a deep limitation of optical spectroscopy in characterizing hyperfluorescent systems.
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Affiliation(s)
- Nils Haase
- Institute of Physics, Experimental Physics IV, University of Augsburg, Universitätsstr. 1, 86135 Augsburg, Germany
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25
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Abstract
This review article focuses on the understanding of intersystem crossing (ISC) in molecules. It addresses readers who are interested in the phenomenon of intercombination transitions between states of different electron spin multiplicities but are not familiar with relativistic quantum chemistry. Among the spin-dependent interaction terms that enable a crossover between states of different electron spin multiplicities, spin-orbit coupling (SOC) is by far the most important. If SOC is small or vanishes by symmetry, ISC can proceed by electronic spin-spin coupling (SSC) or hyperfine interaction (HFI). Although this review discusses SSC- and HFI-based ISC, the emphasis is on SOC-based ISC. In addition to laying the theoretical foundations for the understanding of ISC, the review elaborates on the qualitative rules for estimating transition probabilities. Research on the mechanisms of ISC has experienced a major revival in recent years owing to its importance in organic light-emitting diodes (OLEDs). Exemplified by challenging case studies, chemical substitution and solvent environment effects are discussed with the aim of helping the reader to understand and thereby get a handle on the factors that steer the efficiency of ISC.
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Affiliation(s)
- Christel M Marian
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University, Düsseldorf 40204, Germany;
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26
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Cai W, Ren K, Zhao A, Wu X, He R, Li M, Shen W. The study of intramolecular decay and intermolecular energy transfer for phosphorescent organic light-emitting devices. Phys Chem Chem Phys 2021; 23:7495-7503. [PMID: 33876109 DOI: 10.1039/d1cp00109d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Due to the huge potential of organic light-emitting diodes (OLEDs) in optical display devices, the exciton utilization of devices should be elucidated comprehensively to achieve a high external quantum efficiency (EQE). In this study, theoretical calculations of intramolecular excited state decay and intermolecular excitation energy transfer (EET) were conducted to investigate the differences in EQE between the two studied systems. Compared to the PtOO7-based system (using PtOO7 as the guest and 26mCPy as the host), the greater EQE of the PtON7-based system (using PtON7 as the guest and 26mCPy as the host) was mainly governed by the stronger energy transfer efficiency, with a secondary role being played by the higher photoluminescence quantum yield of the emitter. We confirmed that the different triplet EET (TEET) rates mainly contribute to the difference in the energy transfer efficiency between two studied systems, where the higher TEET rate from 26mCPy to PtON7 can be attributed to the restrained structural deformation of PtON7 and the desirable energy gap in the energy transfer process. Our calculations indicated that the electronic structure can evidently affect the intramolecular excited state decay and intermolecular excitation energy transfer. In addition, considering the environmental effects on the emission spectra of the emitters, the simulated spectra were consistent with the experimental measurements, which indicated that our descriptions of electronic structures are accurate; furthermore, an effective description of the molecular environment should be obtained. Our computational protocol successfully explored the relationship between the electronic structures, intramolecular excited state decay, and intermolecular excitation energy transfer, which can provide a deep understanding for the design and development of high-quality OLEDs from a molecular perspective.
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Affiliation(s)
- Wanlin Cai
- Key Laboratory of Luminescence and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
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27
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Moon YK, Jang HJ, Hwang S, Kang S, Kim S, Oh J, Lee S, Kim D, Lee JY, You Y. Modeling Electron-Transfer Degradation of Organic Light-Emitting Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2003832. [PMID: 33586272 DOI: 10.1002/adma.202003832] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 12/14/2020] [Indexed: 06/12/2023]
Abstract
The operational lifetime of organic light-emitting devices (OLEDs) is governed primarily by the intrinsic degradation of the materials. Therefore, a chemical model capable of predicting the operational stability is highly important. Here, a degradation model for OLEDs that exhibit thermally activated delayed fluorescence (TADF) is constructed and validated. The degradation model involves Langevin recombination of charge carriers on hosts, followed by the generation of a polaron pair through reductive electron transfer from a dopant to a host exciton as the initiation steps. The polarons undergo spontaneous decomposition, which competes with ultrafast recovery of the intact materials through charge recombination. Electrical and spectroscopic investigations provide information about the kinetics of each step in the operation and degradation of the devices, thereby enabling the building of mass balances for the key species in the emitting layers. Numerical solutions enable predictions of temporal decreases of the dopant concentration in various TADF emitting layers. The simulation results are in good agreement with experimental operational stabilities. This research disentangles the chemical processes in intrinsic electron-transfer degradation, and provides a useful foundation for improving the longevity of OLEDs.
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Affiliation(s)
- Yu Kyung Moon
- Division of Chemical Engineering and Materials Science, and System, Health and Engineering Convergence Major, Ewha Womans University, Seoul, 03760, Republic of Korea
| | - Ho Jin Jang
- School of Chemical Engineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Sanju Hwang
- Department of Chemistry and Spectroscopy Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul, 03722, Republic of Korea
| | - Seongsoo Kang
- Department of Chemistry and Spectroscopy Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul, 03722, Republic of Korea
| | - Sinheui Kim
- Division of Chemical Engineering and Materials Science, and System, Health and Engineering Convergence Major, Ewha Womans University, Seoul, 03760, Republic of Korea
| | - Juwon Oh
- Department of Chemistry and Spectroscopy Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul, 03722, Republic of Korea
| | - Sangheon Lee
- Division of Chemical Engineering and Materials Science, and System, Health and Engineering Convergence Major, Ewha Womans University, Seoul, 03760, Republic of Korea
| | - Dongho Kim
- Department of Chemistry and Spectroscopy Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul, 03722, Republic of Korea
| | - Jun Yeob Lee
- School of Chemical Engineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Youngmin You
- Division of Chemical Engineering and Materials Science, and System, Health and Engineering Convergence Major, Ewha Womans University, Seoul, 03760, Republic of Korea
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28
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Liu Y, Tong X, Chen X, Wang Y, Ying S, Ren Z, Yan S. Enhanced Upconversion of Triplet Excitons for Conjugated Polymeric Thermally Activated Delayed Fluorescence Emitters by Employing an Intramolecular Sensitization Strategy. ACS APPLIED MATERIALS & INTERFACES 2021; 13:8997-9005. [PMID: 33570400 DOI: 10.1021/acsami.0c22494] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Endowed by a thermally activated delayed fluorescence (TADF) sensitizer with a high constant rate of reverse intersystem crossing, the singlet excitons could be accumulated and then delivered to emitting states through favorable Förster resonance energy transfer, bypassing the inefficient intersystem transition processes of emitters. However, the conventional intermolecular sensitization strategies suffer from inherent aggregation-induced quenching and inevitable phase segregation of TADF sensitizers and emitters. In this context, we proposed a novel intramolecular sensitization strategy by covalently incorporating the TADF sensitizer into conjugated polymeric emitters. After rationally regulating the proportions of sensitizer and emitter units in polymers, the intramolecular sensitized conjugated TADF polymers with anticipated photophysical properties and stable device performance were obtained. A superior kRISC value over 106 s-1 accompanied by a suppressed nonradiative transition of the triplet exciton could be gained; therefore, the photoluminescence quantum yield (PLQY) could reach nearly 90%. In accord with the superior PLQY values enhanced by our intramolecular sensitization strategy, the solution-processed organic light-emitting diodes (OLEDs) can achieve a maximum external quantum efficiency (EQE) value of 17.8% while still maintaining 16.0% at 1000 cd/m2 with extremely low efficiency roll-off. These results convincingly manifest the significance of an intramolecular sensitization strategy for designing high-efficiency polymeric TADF emitters.
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Affiliation(s)
- Yuchao Liu
- Key Laboratory of Rubber-Plastics, Ministry of Education, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
- State Key Laboratory of Chemical Resource Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xingwen Tong
- State Key Laboratory of Chemical Resource Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xinrui Chen
- Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, School of Materials Science and Engineering, Changzhou University, Changzhou 213164, China
| | - Yafei Wang
- Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, School of Materials Science and Engineering, Changzhou University, Changzhou 213164, China
| | - Shian Ying
- Key Laboratory of Rubber-Plastics, Ministry of Education, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
| | - Zhongjie Ren
- State Key Laboratory of Chemical Resource Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Shouke Yan
- Key Laboratory of Rubber-Plastics, Ministry of Education, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
- State Key Laboratory of Chemical Resource Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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29
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Polgar AM, Tonge CM, Christopherson CJ, Paisley NR, Reyes AC, Hudson ZM. Thermally Assisted Fluorescent Polymers: Polycyclic Aromatic Materials for High Color Purity and White-Light Emission. ACS APPLIED MATERIALS & INTERFACES 2020; 12:38602-38613. [PMID: 32846499 DOI: 10.1021/acsami.0c07892] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Thermally activated delayed fluorescence (TADF) sensitization of fluorescence is a promising strategy to improve the color purity and operational lifetime of conventional TADF organic light-emitting diodes (OLEDs). Here, we propose a new design strategy for TADF-sensitized fluorescence based on acrylic polymers with a pendant energy-harvesting host, a TADF sensitizer, and fluorescent emitter monomers. Fluorescent emitters were rationally designed from a series of homologous polycyclic aromatic amines, resulting in efficient and color-pure polymeric fluorophores capable of harvesting both singlet and triplet excitons. Macromolecular analogues of blue, green, and yellow fourth-generation OLED emissive layers were prepared in a facile manner by Cu(0) reversible deactivation radical polymerization, with emission quantum yields up to 0.83 in air and narrow emission bands with full width at half-maximum as low as 57 nm. White-light emission can easily be achieved by enforcing incomplete energy transfer between a deep blue TADF sensitizer and yellow fluorophore to yield a single white-emissive polymer with CIE coordinates (0.33, 0.39) and quantum yield 0.77. Energy transfer to the fluorescent emitters occurs at rates of 1-4 × 108 s-1, significantly faster than deactivation caused by internal conversion or intersystem crossing. Rapid energy transfer facilitates high triplet exciton utilization and efficient sensitized emission, even when TADF emitters with a low quantum yield are used as photosensitizers. Our results indicate that a broad library of untapped polymers exhibiting efficient TADF-sensitized fluorescence should be readily accessible from known TADF materials, including many monomers previously thought unsuitable for use in OLEDs.
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Affiliation(s)
- Alexander M Polgar
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Christopher M Tonge
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Cheyenne J Christopherson
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Nathan R Paisley
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Annelie C Reyes
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Zachary M Hudson
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
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30
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Xie FM, Zou SJ, Li Y, Lu LY, Yang R, Zeng XY, Zhang GH, Chen J, Tang JX. Management of Delayed Fluorophor-Sensitized Exciton Harvesting for Stable and Efficient All-Fluorescent White Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2020; 12:16736-16742. [PMID: 32193927 DOI: 10.1021/acsami.0c04251] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
White organic light-emitting diodes (WOLEDs) using thermally activated delayed fluorescence (TADF)-based single emissive layer (SEL) have attracted enormous attention because of their simple device structure and full exciton utilization potential for high efficiency. However, WOLEDs made of an all-TADF SEL usually exhibit serious efficiency roll-off and poor color stability due to serious exciton-annihilation and unbalanced radiative decays of different TADF emitters. Herein, a new strategy is proposed to manipulate the TADF-sensitized fluorescence process by combining dual-host systems of high triplet energy with a conventional fluorescent emitter of complementary color. The multiple energy-funneling paths are modulated and short-range Dexter energy transfer is largely suppressed due to the steric effect of peripheral tert-butyl group in the blue TADF sensitizer. The resulting all-fluorescent WOLEDs achieve an unprecedentedly high external quantum efficiency of 21.8% with balanced white emission of Commission Internationale de l'Eclairage coordinate of (0.292, 0.343), accompanied with good color stability, reduced efficiency roll-off, and prolonged operational lifetime. These findings demonstrate the validity of this strategy for precisely allocating the exciton harvesting in SEL WOLEDs.
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Affiliation(s)
- Feng-Ming Xie
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, China
| | - Shi-Jie Zou
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, China
| | - Yanqing Li
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, China
- School of Physics and Electronics Science, Nanophotonics & Advanced Instrument Engineering Research Center, Ministry of Education, East China Normal University, Shanghai 200062, China
| | - Lin-Yang Lu
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, China
| | - Rui Yang
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, China
| | - Xin-Yi Zeng
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, China
| | - Guang-Hui Zhang
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, China
| | - Jingde Chen
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, China
| | - Jian-Xin Tang
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, Jiangsu, China
- Institute of Organic Optoelectronics (IOO), JITRI, Wujiang, Suzhou 215215, China
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31
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High energy acceptor states strongly enhance exciton transfer between metal organic phosphorescent dyes. Nat Commun 2020; 11:1292. [PMID: 32157092 PMCID: PMC7064524 DOI: 10.1038/s41467-020-15034-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 02/12/2020] [Indexed: 12/05/2022] Open
Abstract
Exciton management in organic light-emitting diodes (OLEDs) is vital for improving efficiency, reducing device aging, and creating new device architectures. In particular in white OLEDs, exothermic Förster-type exciton transfer, e.g. from blue to red emitters, plays a crucial role. It is known that a small exothermicity partially overcomes the spectral Stokes shift, enhancing the fraction of resonant donor-acceptor pair states and thus the Förster transfer rate. We demonstrate here a second enhancement mechanism, setting in when the exothermicity exceeds the Stokes shift: transfer to multiple higher-lying electronically excited states of the acceptor molecules. Using a recently developed computational method we evaluate the Förster transfer rate for 84 different donor–acceptor pairs of phosphorescent emitters. As a result of the enhancement the Förster radius tends to increase with increasing exothermicity, from around 1 nm to almost 4 nm. The enhancement becomes particularly strong when the excited states have a large spin-singlet character. Exciton management in phosphorescent organic light-emitting diodes is critical to the optimal design and performance of these devices. Here, the authors report a computational method to elucidate the enhancement in exothermic exciton transfer between different phosphorescent emitters.
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32
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Lim H, Cheon HJ, Lee GS, Kim M, Kim YH, Kim JJ. Enhanced Triplet-Triplet Annihilation of Blue Fluorescent Organic Light-Emitting Diodes by Generating Excitons in Trapped Charge-Free Regions. ACS APPLIED MATERIALS & INTERFACES 2019; 11:48121-48127. [PMID: 31774270 DOI: 10.1021/acsami.9b15303] [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
Three new anthracene-cored molecules, 3,3'-(5-(10-(naphthalen-1-yl)anthracen-9-yl)-1,3-phenylene)dipyridine (AP3Py-Na), 3,3'-(5-(10-(naphthalen-2-yl)anthracen-9-yl)-1,3-phenylene)dipyridine (AP3Py-2Na), and 9,10-bis(3,5-di(pyridin-3-yl)phenyl)anthracene (ADP3Py), were synthesized to be used as an efficiency-enhancement layer (EEL) in blue fluorescent organic light-emitting diodes. Insertion of a very thin EEL (3 nm) between the deep blue emitting layer (EML) and the electron transport layer enhanced the external quantum efficiency (EQE) of the blue device by 44% compared to the device without the EEL, resulting in an EQE of 7.9% and a current efficiency of 9.0 cd A-1 at 1000 cd m-2; the CIE coordinates of the emitting color were (0.13, 0.14). The transient electroluminescence showed that the efficiency enhancement originates from the triplet-triplet annihilation (TTA) process in the EEL, followed by energy transfer to the emitting dye in the EML.
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Affiliation(s)
| | - Hyung Jin Cheon
- School of Materials Science and Engineering , Gyeongsang National University , 501, Jinju-daero , Jinju-si 660-701 , Gyeongsangnam-do , South Korea
| | - Gyeong Seok Lee
- School of Materials Science and Engineering , Gyeongsang National University , 501, Jinju-daero , Jinju-si 660-701 , Gyeongsangnam-do , South Korea
| | - Mikyung Kim
- Samsung Display Company, Limited , 95 Samsung 2-ro , Giheung-gu, Yongin-si 446-711 , Gyeonggi-Do , South Korea
| | - Yun-Hi Kim
- School of Materials Science and Engineering , Gyeongsang National University , 501, Jinju-daero , Jinju-si 660-701 , Gyeongsangnam-do , South Korea
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33
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Affiliation(s)
- Daniel Escudero
- Department of ChemistryKU Leuven Celestijnenlaan 200F B-3001 Leuven Belgium
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