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Zhao F, Kong J, Zhang W, Kuang Z, Zhou M. Triplet Excited-State Dynamics in Benzothiadiazole-Based Thermally Activated Delayed Fluorescence Compound. J Phys Chem Lett 2024:2885-2892. [PMID: 38447087 DOI: 10.1021/acs.jpclett.4c00145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
The "hot exciton" thermally activated delayed fluorescence (TADF) materials have attracted considerable research interest for their utilization of high-lying triplet excitons. In this work, we reported the mechanism of photoluminescence by revealing the spectral evolution from singlet to triplet states in "hot exciton" TADF molecules by transient absorption (TA) spectra and triplet sensitization experiments. The internal conversion and intersystem crossing are much faster than reverse intersystem crossing (RISC), so that high-lying triplet states (Tn) are difficult to accumulate to be observed in the transient absorption spectra. In contrast, the emergence of delayed fluorescence in time-resolved emission spectra demonstrates the existence of a high-lying RISC process (hRISC) from Tn to S1. Triplet sensitization experiments successfully identified the spectral features of the T1 state in the TA spectra. This work sheds light on critical factors for the systematic design of these materials to achieve a high emission quantum yield.
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Affiliation(s)
- Fangming Zhao
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Anhui 230026, China
| | - Jie Kong
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Anhui 230026, China
| | - Wei Zhang
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Anhui 230026, China
| | - Zhuoran Kuang
- School of Science, Beijing University of Posts and Telecommunications (BUPT), Beijing 100876, P. R. China
| | - Meng Zhou
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Anhui 230026, China
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van Oort B, Roy LM, Xu P, Lu Y, Karcher D, Bock R, Croce R. Revisiting the Role of Xanthophylls in Nonphotochemical Quenching. J Phys Chem Lett 2018; 9:346-352. [PMID: 29251936 DOI: 10.1021/acs.jpclett.7b03049] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Photoprotective nonphotochemical quenching (NPQ) of absorbed solar energy is vital for survival of photosynthetic organisms, and NPQ modifications significantly improve plant productivity. However, the exact NPQ quenching mechanism is obscured by discrepancies between reported mechanisms, involving xanthophyll-chlorophyll (Xan-Chl) and Chl-Chl interactions. We present evidence of an experimental artifact that may explain the discrepancies: strong laser pulses lead to the formation of a novel electronic species in the major plant light-harvesting complex (LHCII). This species evolves from a high excited state of Chl a and is absent with weak laser pulses. It resembles an excitonically coupled heterodimer of Chl a and lutein (or other Xans at site L1) and acts as a de-excitation channel. Laser powers, and consequently amounts of artifact, vary strongly between NPQ studies, thereby explaining contradicting spectral signatures attributed to NPQ. Our results offer pathways toward unveiling NPQ mechanisms and highlight the necessity of careful attention to laser-induced artifacts.
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Affiliation(s)
- Bart van Oort
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Sciences, and LaserLaB Amsterdam, Vrije Universiteit Amsterdam , 1081 HV Amsterdam, The Netherlands
| | - Laura M Roy
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Sciences, and LaserLaB Amsterdam, Vrije Universiteit Amsterdam , 1081 HV Amsterdam, The Netherlands
| | - Pengqi Xu
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Sciences, and LaserLaB Amsterdam, Vrije Universiteit Amsterdam , 1081 HV Amsterdam, The Netherlands
| | - Yinghong Lu
- Max-Planck-Institut für Molekulare Pflanzenphysiologie Wissenschaftspark Golm , Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Daniel Karcher
- Max-Planck-Institut für Molekulare Pflanzenphysiologie Wissenschaftspark Golm , Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie Wissenschaftspark Golm , Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Roberta Croce
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Sciences, and LaserLaB Amsterdam, Vrije Universiteit Amsterdam , 1081 HV Amsterdam, The Netherlands
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