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Pan ML, Hsu CH, Lin YD, Chen BH, Lu CH, Yang SD, Chou PT, Wu YT. Overcrowded 14,14'-Bidibenzo[a,j]anthracenes: Challenges in Syntheses and Atypical Property of Lacking Symmetry-Breaking Charge Transfer (SBCT). Chemistry 2024; 30:e202401063. [PMID: 38654592 DOI: 10.1002/chem.202401063] [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: 03/15/2024] [Revised: 04/17/2024] [Accepted: 04/23/2024] [Indexed: 04/26/2024]
Abstract
14,14'-Bidibenzo[a,j]anthracenes (BDBAs) were prepared by iridium-catalyzed annulation of 5,5'-biterphenylene with alkynes. The molecular geometries of overcrowded BDBAs were verified by X-ray crystallography. The two dibenzo[a,j]anthryl moieties are connected through the sterically hindered 14 positions, resulting in highly distorted molecular halves. The conformation with a small twist angle between two molecular halves can minimize steric conflicts between the substituents at 1 and 13 positions and the carbon atoms of the central axis, as well as steric clashes between those substituents. One such example is octafluoro-substituted BDBA, where the interplanar angle between two anthryl moieties is approximately 31° (currently the lowest reported value, cf. 81° in 9,9'-bianthracene). The intramolecular interactions and electronic couplings between two molecular halves resulted in upfield 1H NMR signals, redshifted absorption and emission bands, and a reduced HOMO-LUMO gap. Photodynamic investigations on BDBAs indicated that the formation of the conventional symmetry-breaking charge transfer (SBCT) state was suspended by restricted rocking around the central C-C bond. Such a mechanism associated with this highly constrained conformation was examined for the first time.
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Affiliation(s)
- Ming-Lun Pan
- Department of Chemistry, National Cheng Kung University, No. 1 Ta-Hsueh Rd., 701401, Tainan, Taiwan
| | - Chao-Hsien Hsu
- Department of Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., 106319, Taipei, Taiwan
| | - Yan-Ding Lin
- Department of Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., 106319, Taipei, Taiwan
| | - Bo-Han Chen
- Institute of Photonics Technologies, National Tsing Hua University, No.101, Section 2, Kuang-Fu Rd., 300044, Hsinchu, Taiwan
| | - Chih-Hsuan Lu
- Institute of Photonics Technologies, National Tsing Hua University, No.101, Section 2, Kuang-Fu Rd., 300044, Hsinchu, Taiwan
| | - Shang-Da Yang
- Institute of Photonics Technologies, National Tsing Hua University, No.101, Section 2, Kuang-Fu Rd., 300044, Hsinchu, Taiwan
| | - Pi-Tai Chou
- Department of Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., 106319, Taipei, Taiwan
| | - Yao-Ting Wu
- Department of Chemistry, National Cheng Kung University, No. 1 Ta-Hsueh Rd., 701401, Tainan, Taiwan
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Gao Y, Wang Y, Guo Z, Wan Y, Xue Z, Han Y, Yang W, Ma X. Ultrafast photophysics of an orange-red thermally activated delayed fluorescence emitter: the role of external structural restraint. Chem Sci 2024; 15:6410-6420. [PMID: 38699269 PMCID: PMC11062098 DOI: 10.1039/d4sc00460d] [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: 01/19/2024] [Accepted: 03/21/2024] [Indexed: 05/05/2024] Open
Abstract
The application of thermally activated delay fluorescence (TADF) emitters in the orange-red regime usually suffers from the fast non-radiative decay of emissive singlet states (kSNR), leading to low emitting efficiency in corresponding organic light-emitting diode (OLED) devices. Although kSNR has been quantitatively described by energy gap law, how ultrafast molecular motions are associated with the kSNR of TADF emitters remains largely unknown, which limits the development of new strategies for improving the emitting efficiency of corresponding OLED devices. In this work, we employed two commercial TADF emitters (TDBA-Ac and PzTDBA) as a model system and attempted to clarify the relationship between ultrafast excited-state structural relaxation (ES-SR) and kSNR. Spectroscopic and theoretical investigations indicated that S1/S0 ES-SR is directly associated with promoting vibrational modes, which are considerably involved in electronic-vibrational coupling through the Huang-Rhys factor, while kSNR is largely affected by the reorganization energy of the promoting modes. By restraining S1/S0 ES-SR in doping films, the kSNR of TADF emitters can be greatly reduced, resulting in high emitting efficiency. Therefore, by establishing the connection among S1/S0 ES-SR, promoting modes and kSNR of TADF emitters, our work clarified the key role of external structural restraint for achieving high emitting efficiency in TADF-based OLED devices.
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Affiliation(s)
- Yixuan Gao
- Institute of Molecular Plus, Tianjin University Tianjin 300072 P. R. China
| | - Yaxin Wang
- Institute of Molecular Plus, Tianjin University Tianjin 300072 P. R. China
| | - Zilong Guo
- Institute of Molecular Plus, Tianjin University Tianjin 300072 P. R. China
| | - Yan Wan
- College of Chemistry, Beijing Normal University Beijing 100875 P. R. China
| | - Zheng Xue
- Engineering Research Center for Nanomaterials, Henan University Kaifeng 475004 P. R. China
| | - Yandong Han
- Engineering Research Center for Nanomaterials, Henan University Kaifeng 475004 P. R. China
| | - Wensheng Yang
- Institute of Molecular Plus, Tianjin University Tianjin 300072 P. R. China
- Engineering Research Center for Nanomaterials, Henan University Kaifeng 475004 P. R. China
| | - Xiaonan Ma
- Institute of Molecular Plus, Tianjin University Tianjin 300072 P. R. China
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Majdecki M, Hsu CH, Wang CH, Shi EHC, Zakrocka M, Wei YC, Chen BH, Lu CH, Yang SD, Chou PT, Gaweł P. Singlet Fission in a New Series of Systematically Designed Through-space Coupled Tetracene Oligomers. Angew Chem Int Ed Engl 2024; 63:e202401103. [PMID: 38412017 DOI: 10.1002/anie.202401103] [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: 01/16/2024] [Revised: 02/14/2024] [Accepted: 02/24/2024] [Indexed: 02/28/2024]
Abstract
Singlet fission (SF) holds great promise for current photovoltaic technologies, where tetracenes, with their relatively high triplet energies, play a major role for application in silicon-based solar cells. However, the SF efficiencies in tetracene dimers are low due to the unfavorable energetics of their singlet and triplet energy levels. In the solid state, tetracene exhibits high yields of triplet formation through SF, raising great interest about the underlying mechanisms. To address this discrepancy, we designed and prepared a novel molecular system based on a hexaphenylbenzene core decorated with 2 to 6 tetracene chromophores. The spatial arrangement of tetracene units, induced by steric hindrance in the central part, dictates through-space coupling, making it a relevant model for solid-state chromophore organization. We then revealed a remarkable increase in SF quantum yield with the number of tetracenes, reaching quantitative (196 %) triplet pair formation in hexamer. We observed a short-lived correlated triplet pair and limited magnetic effects, indicating ineffective triplet dissociation in these through-space coupled systems. These findings emphasize the crucial role of the number of chromophores involved and the interchromophore arrangement for the SF efficiency. The insights gained from this study will aid designing more efficient and technology-compatible SF systems for applications in photovoltaics.
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Affiliation(s)
- Maciej Majdecki
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Chao-Hsien Hsu
- Department of Chemistry, National Taiwan University, Taipei, 10617, Taiwan
| | - Chih-Hsing Wang
- Department of Chemistry, National Taiwan University, Taipei, 10617, Taiwan
| | - Emily Hsue-Chi Shi
- Department of Chemistry, National Taiwan University, Taipei, 10617, Taiwan
| | - Magdalena Zakrocka
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Yu-Chen Wei
- Department of Chemistry, National Taiwan University, Taipei, 10617, Taiwan
| | - Bo-Han Chen
- Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Chih-Hsuan Lu
- Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Shang-Da Yang
- Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Pi-Tai Chou
- Department of Chemistry, National Taiwan University, Taipei, 10617, Taiwan
| | - Przemysław Gaweł
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
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Wang SF, Zhou DY, Kuo KH, Wang CH, Hung CM, Yan J, Liao LS, Hung WY, Chi Y, Chou PT. Effects of Deuterium Isotopes on Pt(II) Complexes and Their Impact on Organic NIR Emitters. Angew Chem Int Ed Engl 2024; 63:e202317571. [PMID: 38230818 DOI: 10.1002/anie.202317571] [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: 11/17/2023] [Revised: 01/05/2024] [Accepted: 01/16/2024] [Indexed: 01/18/2024]
Abstract
Insight into effect of deuterium isotopes on organic near-IR (NIR) emitters was explored by the use of self-assembled Pt(II) complexes H-3-f and HPh-3-f, and their deuterated analogues D-3-f and DPh-3-f, respectively (Scheme 2). In vacuum deposited thin film, albeit having nearly identical emission spectral feature maximized at ~810 nm, H-3-f and D-3-f exhibit remarkable difference in photoluminescence quantum yield (PLQY) of 29 % and 50 %, respectively. Distinction in PLQY is also observed for HPh-3-f (800 nm, 50 %) and DPh-3-f (798 nm, 67 %). We then elucidated the theoretical differences in the impact on near-infrared (NIR) luminescence between Pt(II) complexes and organic small molecules upon deuteration. The results establish a general guideline for the deuteration on NIR emission efficiency. From a perspective of practical application, NIR OLEDs based on D-3-f and DPh-3-f emitters attain EQEmax of 15.5 % (radiance 31,287 mW Sr-1 m-2 ) and 16.6 % (radiance of 32,279 mW Sr-1 m-2 ) at 764 nm and 796 nm, respectively, both of which set new records for NIR OLEDs of >750 nm.
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Affiliation(s)
- Sheng-Fu Wang
- Department of Chemistry, Center for Emerging Materials and Advanced Devices, National Taiwan University, 106319, Taipei, Taiwan
| | - Dong-Ying Zhou
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon Based Functional Materials & Devices, Soochow University, 215123, Suzhou, China
| | - Kai-Hua Kuo
- Department of Chemistry, Center for Emerging Materials and Advanced Devices, National Taiwan University, 106319, Taipei, Taiwan
| | - Chih-Hsing Wang
- Department of Chemistry, Center for Emerging Materials and Advanced Devices, National Taiwan University, 106319, Taipei, Taiwan
| | - Chieh-Ming Hung
- Department of Chemistry, Center for Emerging Materials and Advanced Devices, National Taiwan University, 106319, Taipei, Taiwan
| | - Jie Yan
- Department of Materials Science and Engineering, Department of Chemistry, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, 999077, Kowloon, Hong Kong
| | - Liang-Sheng Liao
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon Based Functional Materials & Devices, Soochow University, 215123, Suzhou, China
| | - Wen-Yi Hung
- Institute of Optoelectronic Sciences, National Taiwan Ocean University, 20224, Keelung, Taiwan
| | - Yun Chi
- Department of Materials Science and Engineering, Department of Chemistry, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, 999077, Kowloon, Hong Kong
| | - Pi-Tai Chou
- Department of Chemistry, Center for Emerging Materials and Advanced Devices, National Taiwan University, 106319, Taipei, Taiwan
- Center for Emerging Materials and Advanced Devices, National Taiwan University, Taiwan
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Pan ML, Hsu CH, Lin YD, Chen WS, Chen BH, Lu CH, Yang SD, Cheng MJ, Chou PT, Wu YT. A New Series of Sandwich-Type 5,5'-Biterphenylenes: Synthetic Challenge, Structural Uniqueness and Photodynamics. Chemistry 2024; 30:e202303523. [PMID: 37997021 DOI: 10.1002/chem.202303523] [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: 10/25/2023] [Revised: 11/21/2023] [Accepted: 11/23/2023] [Indexed: 11/25/2023]
Abstract
A new series of biaryls, bi-linear-terphenylenes (BLTPs), were prepared using the tert-butyllithium-mediated cyclization as the key synthetic step. The three-dimensional structures of the studied compounds were verified using X-ray crystallography and DFT calculations. Tetraaryl(ethynyl)-substituted BLTPs are highly crowded molecules, and the internal rotation around the central C-C bond is restricted due to a high barrier (>50 kcal/mol). These structures contain several aryl/terphenylenyl/aryl sandwiches, where the through-space π-π (TSPP) interactions are strongly reflected in the shielding of 1 H NMR chemical shifts, reduction of oxidation potentials, increasing aromaticity of the central six-membered ring and decreasing antiaromaticity of the four-membered rings in a terphenylenyl moiety based on NICS(0) and iso-chemical shielding surfaces. Despite the restricted C-C bond associated intramolecular TSPP interactions for BLTPs in the ground state, to our surprise, the electronic coupling between two linear terphenylenes (LTPs) in BLTPs in the excited state is weak, so that the excited-state behavior is dominated by the corresponding monomeric LTPs. In other words, all BLTPs undergo ultrafast relaxation dynamics via strong exciton-vibration coupling, acting as a blue-light absorber with essentially no emission.
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Affiliation(s)
- Ming-Lun Pan
- Department of Chemistry, National Cheng Kung University, 70101, Tainan, Taiwan
| | - Chao-Hsien Hsu
- Department of Chemistry, National Taiwan University, 10617, Taipei, Taiwan
| | - Yan-Ding Lin
- Department of Chemistry, National Taiwan University, 10617, Taipei, Taiwan
| | - Wei-Sen Chen
- Department of Chemistry, National Cheng Kung University, 70101, Tainan, Taiwan
| | - Bo-Han Chen
- Institute of Photonics Technologies, National Tsing Hua University, 30013, Hsinchu, Taiwan
| | - Chih-Hsuan Lu
- Institute of Photonics Technologies, National Tsing Hua University, 30013, Hsinchu, Taiwan
| | - Shang-Da Yang
- Institute of Photonics Technologies, National Tsing Hua University, 30013, Hsinchu, Taiwan
| | - Mu-Jeng Cheng
- Department of Chemistry, National Cheng Kung University, 70101, Tainan, Taiwan
| | - Pi-Tai Chou
- Department of Chemistry, National Taiwan University, 10617, Taipei, Taiwan
| | - Yao-Ting Wu
- Department of Chemistry, National Cheng Kung University, 70101, Tainan, Taiwan
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