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Chen YK, Lei J, Wu TL. Elevating the upconversion performance of a multiple resonance thermally activated delayed fluorescence emitter via an embedded azepine approach. Chem Sci 2024; 15:10146-10154. [PMID: 38966359 PMCID: PMC11220617 DOI: 10.1039/d4sc02351j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Accepted: 05/22/2024] [Indexed: 07/06/2024] Open
Abstract
Multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters hold promise for efficient organic light-emitting diodes (OLEDs) and wide gamut displays. An azepine donor is introduced into the boron-nitrogen system for the first time. The highly twisted conformation of a seven-ring embedded new molecule, TAzBN, increases the intermolecular distances, suppressing self-aggregation emission quenching. Meanwhile, the azepine donor is crucial to achieve a narrow singlet-triplet gap (0.03 eV) as well as boost the reverse intersystem crossing (RISC) rate to 8.50 × 105 s-1. It is noteworthy that TAzBN demonstrates an impressive photoluminescence quantum yield of 94%. In addition, its nonsensitized OLED displayed a remarkable external quantum efficiency (EQEmax) with values peaking at 27.3%, and an EQE of 21.4% at 500 cd m-2. This finding shows that when TAzBN is used at a high concentration of 10 wt%, its device maintains efficiency even at higher brightness levels, highlighting TAzBN's resistance to aggregation quenching. Furthermore, TAzBN enantiomers showed circularly polarized photoluminescence characteristics with dissymmetry factors |g PL| of up to 1.07 × 10-3 in doped films. The curved heptagonal geometry opens an avenue to design the MR-TADF emitters with fast spin-flip and chiroptical properties.
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Affiliation(s)
- Yi-Kuan Chen
- Department of Chemistry, National Tsing Hua University No. 101, Sec. 2, Kuang-Fu Rd. Hsinchu 300044 Taiwan
| | - Jian Lei
- Department of Chemistry, National Tsing Hua University No. 101, Sec. 2, Kuang-Fu Rd. Hsinchu 300044 Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica No. 1, Sec. 4, Roosevelt Rd. Taipei 106319 Taiwan
| | - Tien-Lin Wu
- Department of Chemistry, National Tsing Hua University No. 101, Sec. 2, Kuang-Fu Rd. Hsinchu 300044 Taiwan
- College of Semiconductor Research No. 101, Sec. 2, Kuang-Fu Rd. Hsinchu 300044 Taiwan
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Lei J, Lou TA, Chen CR, Chuang CH, Liu HY, Hsu LY, Chao YC, Wu TL. Introduction of a Chiral Biphenanthrene-Diol Unit to Achieve Circularly Polarized Thermally Activated Delayed Fluorescence. Chem Asian J 2024; 19:e202300940. [PMID: 38100510 DOI: 10.1002/asia.202300940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 12/13/2023] [Accepted: 12/15/2023] [Indexed: 12/17/2023]
Abstract
Circularly polarized luminescence (CPL) materials are promising candidates for future display technology. However, such highly efficient emitters suffer from the issues of difficult chiral separation and low photoluminescence quantum yield (PLQY). In this work, the chiral 4,4'-biphenanthrene-3,3'-diol (BIPOL) unit was introduced into a thermally activated delayed fluorescence (TADF) framework for the first time. We presented two series of enantiomers, R/S-o-DCzBPNCN and R/S-p-DCzBPNCN, and the synthesis of enantiopure BIPOL can be prepared via normal column chromatography. Notably, o-DCzBPNCN showed narrow singlet-triplet gap of 0.05 eV, efficient TADF, and high PLQYs of 82 % in doped films. In addition, R/S-o-DCzBPNCN exhibited high luminescence dissymmetry factor (gPL ) values of -1.94×10-2 /+1.91×10-2 in doped films. The strategy of BIPOL introduction offers a new approach to organic emitters with stereospecific synthesis, TADF, and chiroptical properties.
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Affiliation(s)
- Jian Lei
- Department of Chemistry, National Tsing Hua University, No. 101, Sec. 2, Kuang-Fu Rd., Hsinchu, 30013, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
| | - Ting-An Lou
- Department of Chemistry, National Tsing Hua University, No. 101, Sec. 2, Kuang-Fu Rd., Hsinchu, 30013, Taiwan
| | - Chong-Rui Chen
- Department of Chemistry, National Tsing Hua University, No. 101, Sec. 2, Kuang-Fu Rd., Hsinchu, 30013, Taiwan
| | - Chia-Hsiang Chuang
- Department of Physics, National Taiwan Normal University, Taipei, 11677, Taiwan
| | - Hau-Yu Liu
- Department of Chemistry, National Tsing Hua University, No. 101, Sec. 2, Kuang-Fu Rd., Hsinchu, 30013, Taiwan
| | - Liang-Yan Hsu
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
- Physics Division, National Center for Theoretical Sciences, Taipei, 106, Taiwan
| | - Yu-Chiang Chao
- Department of Physics, National Taiwan Normal University, Taipei, 11677, Taiwan
| | - Tien-Lin Wu
- Department of Chemistry, National Tsing Hua University, No. 101, Sec. 2, Kuang-Fu Rd., Hsinchu, 30013, Taiwan
- College of Semiconductor Research, National Tsing Hua University, No. 101, Sec. 2, Kuang-Fu Rd., Hsinchu, 30013, Taiwan
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Deng SL, Chen YK, Lei J, Jayakumar J, Ko CL, Hung WY, Wu TL, Cheng CH. Modifications of Pyridine-3,5-dicarbonitrile Acceptor for Highly Efficient Green-to-Red Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37418573 DOI: 10.1021/acsami.3c05243] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/09/2023]
Abstract
The strategy of acceptor modification is a powerful technique for tuning the emission color of thermally activated delayed fluorescence (TADF) emitters. In this study, we have successfully designed and synthesized three TADF emitters with donor-acceptor (D-A) structures using a 4-(diphenylamino)-2,6-dimethylphenyl (TPAm) donor and various pyridine-3,5-dicarbonitrile (PC) acceptor units. As a result, three compounds named TPAmbPPC, TPAm2NPC, and TPAmCPPC exhibited greenish-yellow to orange-red emissions with high photoluminescent quantum yields (76-100%) in thin films. Remarkably, a greenish-yellow device based on TPAmbPPC and TPAm2NPC showed a high maximum external quantum efficiency (EQEmax) of 39.1 and 39.0%, respectively. Furthermore, benefiting from the suitable steric hindrance between the acceptor and donor, the nondoped organic light-emitting diodes (OLEDs) based on TPAmbPPC demonstrated an exceptional EQEmax of 21.6%, indicating its promising potential as an efficient emitter for the application of OLED applications. Furthermore, orange-red OLED devices based on TPAmCPPC exhibited a high EQEmax of 26.2%, a CE of 50.1 cd A-1, and a PE of 52.4 lm W-1.
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Affiliation(s)
- Sheng-Lin Deng
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan
| | - Yi-Kuan Chen
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan
| | - Jian Lei
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | | | - Chang-Lun Ko
- Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 20224, Taiwan
| | - Wen-Yi Hung
- Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 20224, Taiwan
| | - Tien-Lin Wu
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan
- College of Semiconductor Research, National Tsing Hua University, Hsinchu 300044, Taiwan
| | - Chien-Hong Cheng
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
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Adachi Y, Hasegawa T, Ohshita J. Highly luminescent antiaromatic diborinines with fused thiophene rings. Dalton Trans 2023. [PMID: 37357987 DOI: 10.1039/d3dt01841e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
Tricoordinate boron-incorporated π-conjugated systems are widely investigated as optoelectronic materials because of their unique p-π* orbital interactions and high Lewis acidity. Among them, thiophene-fused diborinines are characterized by moderate antiaromaticity and extended conjugation. In this work, we have developed two new dithienodiborinines with C2h and C2v symmetries, which exhibited completely different optical properties. The thiophene-fused diborinines synthesized in this study showed excellent fluorescence properties both in solution and in the solid state, with quantum yields of up to 95%. The high antiaromaticity enhanced the Lewis acidity of the boron centers, as proven by the large association constants with fluoride ion estimated from titration experiments. The high Lewis acidity and the superior luminescence property have enabled their application as fluorescent sensor materials for the detection of ammonia vapor.
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Affiliation(s)
- Yohei Adachi
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan.
| | - Takumi Hasegawa
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan.
| | - Joji Ohshita
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan.
- Digital Monozukuri (Manufacturing) Education and Research Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan.
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