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Wu H, Shi YZ, Wang K, Yu J, Zhang XH. Conformational isomeric thermally activated delayed fluorescence (TADF) emitters: mechanism, applications, and perspectives. Phys Chem Chem Phys 2023; 25:2729-2741. [PMID: 36633179 DOI: 10.1039/d2cp05119b] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Thermally activated delayed fluorescence (TADF) materials have received enormous attention and the mechanism behind them has been investigated in depth. It has been found that some donor-acceptor (D-A) type TADF emitters could obviously exhibit dual stable conformations in the ground states and their distributions significantly affect the physical properties and device performances. Therefore, professional analysis and a summary of the relationship between molecular structures and performances are very important. In this review, we first summarize the mechanism and properties of TADF emitters with conformational isomerism. We also classify their recent progress according to their different applications, and provide an outlook on their perspectives.
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Affiliation(s)
- Hao Wu
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, P. R. China.
| | - Yi-Zhong Shi
- School of Materials Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215009, P. R. China.
| | - Kai Wang
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, P. R. China. .,Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, 215123, Jiangsu, P. R. China
| | - Jia Yu
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, P. R. China. .,Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123, Jiangsu, P. R. China
| | - Xiao-Hong Zhang
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, P. R. China. .,Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123, Jiangsu, P. R. China
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2
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Serevičius T, Skaisgiris R, Gudeika D, Kazlauskas K, Juršėnas S. Conformational disorder enabled emission phenomena in heavily doped TADF films. Phys Chem Chem Phys 2021; 24:313-320. [PMID: 34889323 DOI: 10.1039/d1cp04905d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Thermally activated delayed fluorescence (TADF) compounds doped in solid hosts are prone to undergo solvation effects, similar to those in the solution state. Emission peak shifts and changes in emission decay rates usually follow solid-state solvation (SSS). However, here we show that typical SSS behavior in heavily doped TADF films could be of a completely different origin, mistakenly attributed to SSS. Typically, increasing the doping load was found to redshift the emission peak wavelength and enhance the rISC rate. However, more in-depth analysis revealed that SSS actually is negligible and both phenomena are caused by the specific behavior of delayed emission. Increasing the concentration of the TADF compound was shown to enhance the concentration quenching of long-lived delayed fluorescence from conformer states with the largest singlet energy, eventually leading to a gradual redshift of the delayed emission peak wavelength. Concomitantly, the loss of long-lived delayed fluorescence entailed reverse intersystem crossing rate enhancement, though the rate-governing singlet-triplet energy gap was gradually increasing. The observed phenomena are highly unwanted, burdening molecular structure and OLED performance optimization.
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Affiliation(s)
- Tomas Serevičius
- Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio 3, LT-10257 Vilnius, Lithuania.
| | - Rokas Skaisgiris
- Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio 3, LT-10257 Vilnius, Lithuania.
| | - Dalius Gudeika
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu 19, LT-50254 Kaunas, Lithuania
| | - Karolis Kazlauskas
- Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio 3, LT-10257 Vilnius, Lithuania.
| | - Saulius Juršėnas
- Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio 3, LT-10257 Vilnius, Lithuania.
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Nakae T, Nishio M, Usuki T, Ikeya M, Nishimoto C, Ito S, Nishihara H, Hattori M, Hayashi S, Yamada T, Yamanoi Y. Luminescent Behavior Elucidation of a Disilane‐Bridged D–A–D Triad Composed of Phenothiazine and Thienopyrazine. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202108089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Toyotaka Nakae
- Department of Chemistry School of Science The University of Tokyo 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033 Japan
| | - Masaki Nishio
- Department of Chemistry School of Science The University of Tokyo 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033 Japan
| | - Tsukasa Usuki
- Department of Chemistry School of Science The University of Tokyo 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033 Japan
| | - Minako Ikeya
- Department of Chemistry and Life Science Graduate School of Engineering Science Yokohama National University 79-5 Tokiwadai, Hodogaya-ku Yokohama Kanagawa 240-8501 Japan
| | - Chika Nishimoto
- Department of Chemistry and Life Science Graduate School of Engineering Science Yokohama National University 79-5 Tokiwadai, Hodogaya-ku Yokohama Kanagawa 240-8501 Japan
| | - Suguru Ito
- Department of Chemistry and Life Science Graduate School of Engineering Science Yokohama National University 79-5 Tokiwadai, Hodogaya-ku Yokohama Kanagawa 240-8501 Japan
| | - Hiroshi Nishihara
- Research Center for Science and Technology Tokyo University of Science 2641 Yamazaki, Noda-shi Chiba 278-8510 Japan
| | - Mineyuki Hattori
- National Institute of Advanced Industrial Science and Technology AIST Central 5, 1-1-1 Higashi Tsukuba Ibaraki 305-8565 Japan
| | - Shigenobu Hayashi
- National Institute of Advanced Industrial Science and Technology AIST Central 5, 1-1-1 Higashi Tsukuba Ibaraki 305-8565 Japan
| | - Teppei Yamada
- Department of Chemistry School of Science The University of Tokyo 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033 Japan
| | - Yoshinori Yamanoi
- Department of Chemistry School of Science The University of Tokyo 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033 Japan
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Nakae T, Nishio M, Usuki T, Ikeya M, Nishimoto C, Ito S, Nishihara H, Hattori M, Hayashi S, Yamada T, Yamanoi Y. Luminescent Behavior Elucidation of a Disilane-Bridged D-A-D Triad Composed of Phenothiazine and Thienopyrazine. Angew Chem Int Ed Engl 2021; 60:22871-22878. [PMID: 34427025 DOI: 10.1002/anie.202108089] [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: 06/17/2021] [Indexed: 12/28/2022]
Abstract
A σ-π extended aryldisilane, comprising a thienopyrazine group as an acceptor fragment and phenothiazine groups as the donor moiety, has been prepared through the introduction of two Si-Si bridges (compound 1). X-ray diffraction analysis determined the crystal structure of 1, and experimental and theoretical approaches investigated its optical properties. Solvatochromic studies revealed the dual emission of 1 in all solvents tested. Compound 1 also exhibited fluorescence in the solid state upon excitation with a hand-held UV lamp, as well as mechanochromic luminescent properties. The packing mode in the crystal structure, variation of phenothiazine conformation, morphological changes between crystalline and amorphous phases are the major factors showing reversible fluorescence under external stimuli. A theoretical conformer study found that 1 exists in distinct conformational groups differing in Gibbs free energy by less than 3 kcal mol-1 . The conformer in the crystalline state of 1 can promote the complete separation of the HOMO and LUMO between the phenothiazine donor and the thienopyrazine acceptor, linked by the disilane linker. HOMO-LUMO energy transition in the crystalline state is forbidden due to the lack of frontier orbital overlap. Crystalline state emission showed LUMO → HOMO-1 transition (locally excited (LE) state). In the amorphous state, the partial presence of quasi-axial conformers allows intramolecular charge-transfer type emission via energy transfer from dominant quasi-equatorial conformers. The strategy proposed in this work provides important guidance for developing stimuli-responsive materials with controlled excited states.
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Affiliation(s)
- Toyotaka Nakae
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Masaki Nishio
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Tsukasa Usuki
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Minako Ikeya
- Department of Chemistry and Life Science, Graduate School of Engineering Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa, 240-8501, Japan
| | - Chika Nishimoto
- Department of Chemistry and Life Science, Graduate School of Engineering Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa, 240-8501, Japan
| | - Suguru Ito
- Department of Chemistry and Life Science, Graduate School of Engineering Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa, 240-8501, Japan
| | - Hiroshi Nishihara
- Research Center for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba, 278-8510, Japan
| | - Mineyuki Hattori
- National Institute of Advanced Industrial Science and Technology, AIST Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Shigenobu Hayashi
- National Institute of Advanced Industrial Science and Technology, AIST Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Teppei Yamada
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yoshinori Yamanoi
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
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Elliott CF, Fraser KE, Odom SA, Risko C. Steric Manipulation as a Mechanism for Tuning the Reduction and Oxidation Potentials of Phenothiazines. J Phys Chem A 2021; 125:272-278. [PMID: 33398992 DOI: 10.1021/acs.jpca.0c09801] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Synthetic chemists customarily tune the redox characteristics of π-conjugated molecules by introducing electron-donating or electron-withdrawing substituents onto the molecular core, or by modifying the length of the π-conjugated pathway. Any steric effects of such efforts on molecular geometry typically affect both the neutral and charged (oxidized or reduced) states indiscriminately. However, in electroactive systems that undergo significant conformational changes upon oxidation or reduction, we can leverage the steric and inductive effects of substitution to attain considerable control over individual redox potentials. Here, we make use of density functional theory to elucidate the interplay between electronic and geometric effects of peripheral substitution on the model system of phenothiazine. For instance, we introduce substituents at positions ortho to the nitrogen atom (positions 1 and 9) to induce steric strain in the radical-cation state without significant effect on the neutral molecule, thereby augmenting the overall ionization potential. Notably, this steric effect persists for electron-donating substituents; the resulting ionization potentials therefore deviate from outcomes foretold by Hammett constants. Moreover, the same procedure has limited effect on electron affinities because of differences in phenothiazines' relaxation process upon reduction compared to oxidation. Our results promote molecular design guidelines for manipulating redox potentials in classes of electroactive compounds that experience dramatic changes in geometry upon ionization.
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Affiliation(s)
- Corrine F Elliott
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Kate E Fraser
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Susan A Odom
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Chad Risko
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States.,Center for Applied Energy Research, University of Kentucky, Lexington, Kentucky 40511, United States
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Li X, Shen S, Zhang C, Liu M, Lu J, Zhu L. Small-molecule based thermally activated delayed fluorescence materials with dual-emission characteristics. Sci China Chem 2021. [DOI: 10.1007/s11426-020-9908-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Marghad I, Bencheikh F, Wang C, Manolikakes S, Rérat A, Gosmini C, Kim DH, Ribierre JC, Adachi C. Control of the dual emission from a thermally activated delayed fluorescence emitter containing phenothiazine units in organic light-emitting diodes. RSC Adv 2019; 9:4336-4343. [PMID: 35520152 PMCID: PMC9060425 DOI: 10.1039/c8ra10393c] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 01/18/2019] [Indexed: 11/21/2022] Open
Abstract
A novel TADF emitter showing dual emission is synthesized and applied to OLEDs with an external quantum efficiency of 11.5%.
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Affiliation(s)
- Ikbal Marghad
- Center for Organic Photonics and Electronics Research (OPERA)
- Kyushu University
- Fukuoka 819-0395
- Japan
- Laboratoire de chimie moléculaire LCM
| | - Fatima Bencheikh
- Center for Organic Photonics and Electronics Research (OPERA)
- Kyushu University
- Fukuoka 819-0395
- Japan
- Japan Science and Technology Agency (JST)
| | - Chao Wang
- Department of Polymer Science and Engineering
- Zhejiang University
- Hangzhou 310027
- China
| | | | - Alice Rérat
- Laboratoire de chimie moléculaire LCM
- Ecole Polytechnique
- CNRS
- France
| | - Corinne Gosmini
- Laboratoire de chimie moléculaire LCM
- Ecole Polytechnique
- CNRS
- France
| | - Dae hyeon Kim
- Center for Organic Photonics and Electronics Research (OPERA)
- Kyushu University
- Fukuoka 819-0395
- Japan
- Japan Science and Technology Agency (JST)
| | - Jean-Charles Ribierre
- Center for Organic Photonics and Electronics Research (OPERA)
- Kyushu University
- Fukuoka 819-0395
- Japan
- Japan Science and Technology Agency (JST)
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA)
- Kyushu University
- Fukuoka 819-0395
- Japan
- Japan Science and Technology Agency (JST)
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