文献类型：期刊文献

英文题名：Excited-state properties of TCTA:PO-T2T exciplex in solvents investigated by density function theory and transient absorption spectroscopy

作者：Yan, Shujie[1];Lu, Zhaoyue[1];Chen, Zhehao[1];Wang, Xiao[1]

机构：[1]East China Univ Sci & Technol, Sch Phys, Shanghai 200237, Peoples R China

年份：2025

卷号：127

期号：18

外文期刊名：APPLIED PHYSICS LETTERS

收录：;EI(收录号：20254519466322);WOS:【SCI-EXPANDED(收录号:WOS:001608993900004)】；

语种：英文

外文关键词：Binding energy - Blue shift - Density functional theory - Electronic structure - Excited states - Polonium alloys - Quantum chemistry - Quantum theory - Solvents - Transient absorption spectroscopy

摘要：The solvent-dependent excited-state properties of TCTA:PO-T2T mixture are investigated through a combination of quantum chemical calculations with ultrafast transient absorption spectroscopy. Photoluminescence spectroscopy reveals distinct exciplex emission peaked at 580 +/- 5 nm in low-polarity solvents (epsilon = 2.38 for toluene and epsilon = 17.3 for 2Me-THF), while this emission band completely disappears in high-epsilon solvents like DMF (epsilon = 36.7) and DMSO (epsilon = 46.7). This solvent-dependent behavior aligns with the calculated exciplex binding energies, which decrease from -20.6 kcal/mol (toluene) to -13.5 kcal/mol (DMSO), confirming the thermodynamic instability of exciplexes in high-epsilon media. Electronic structure calculations identify solvent-dependent polarization effects that perturb exciplex excited-state energies. These energies are modestly higher in 2Me-THF than in toluene due to the presence of electron-rich oxygen, resulting in a blue shifted emission. Femtosecond transient absorption spectroscopy delivers direct evidence of exciplex formation through the emergence of excited-state absorption between 575 and 700 nm, which evolves on the timescale of hundreds of picoseconds to nanoseconds. This study offers valuable insights into exciplex behavior in solution.