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Direct Observation of Aggregation-Induced Emission Mechanism |
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| Authors: | Jianxin Guan Rong Wei Antonio Prlj Jie Peng Kun-Han Lin Jitian Liu Han Han Prof Clémence Corminboeuf Prof Dahui Zhao Prof Zhihao Yu Prof Junrong Zheng |
| Institution: | 1. College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing, 100871 China;2. College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing, 100871 China
These authors contributed equally to this work.;3. Laboratory for Computational Molecular Design, École polytechnique fédérale de Lausanne, Lausanne, Switzerland These authors contributed equally to this work.;4. Laboratory for Computational Molecular Design, École polytechnique fédérale de Lausanne, Lausanne, Switzerland |
| Abstract: | The mechanism of aggregation-induced emission, which overcomes the common aggregation-caused quenching problem in organic optoelectronics, is revealed by monitoring the real time structural evolution and dynamics of electronic excited state with frequency and polarization resolved ultrafast UV/IR spectroscopy and theoretical calculations. The formation of Woodward–Hoffmann cyclic intermediates upon ultraviolet excitation is observed in dilute solutions of tetraphenylethylene and its derivatives but not in their respective solid. The ultrafast cyclization provides an efficient nonradiative relaxation pathway through crossing a conical intersection. Without such a reaction mechanism, the electronic excitation is preserved in the molecular solids and the molecule fluoresces efficiently, aided by the very slow intermolecular charge and energy transfers due to the well separated molecular packing arrangement. The mechanisms can be general for tuning the properties of chromophores in different phases for various important applications. |
| Keywords: | aggregation-induced emission conical intersections luminescence mechanism ultrafast spectroscopy |