Efficient spatial separation of photogenerated charge carriers across donor/acceptor interfaces has stimulated intense research efforts in photocatalysis fields ascribed to distinctive electronic structure properties of related constituents. Leveraging electronic structure calculations in combination with ab initio-based non-adiabatic carrier dynamics simulations, this study reports ultrafast electron transfer and suppressed nonradiative electron–hole recombination at the interface of PM6/PCBM organic semiconductor heterojunctions, which leads to long-lived charges taking part in hydrogen evolution. The photoinduced dynamical processes are dominantly influenced by energy gaps and non-adiabatic couplings between frontier donor and acceptor states. In addition, hydrogen evolution sites at PM6/PCBM heterojunctions are unveiled by means of first-principles calculations, which suggest that the reaction activity heavily depends on H-adsorbed sites. The activity on the C atoms at the junction of three benzene rings (C666) is much lower than that on the C atoms connected with one pentagon ring and two benzene rings (C665). Nevertheless, the former can be significantly improved via pre-hydrogenating the adjacent C665 atom. This work reveals new photophysical and photochemical properties of PM6/PCBM heterojunctions in detail and provides useful perspectives for performance improvements of photocatalytic materials based on organic donor–acceptor heterojunctions.

中文翻译：

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有机 PM6/PCBM 异质结的光诱导载流子动力学和析氢反应

由于相关成分的独特电子结构特性，在供体/受体界面上光生电荷载流子的有效空间分离激发了光催化领域的激烈研究。结合从头算起利用电子结构计算基于非绝热载流子动力学模拟，本研究报告了在 PM6/PCBM 有机半导体异质结界面处的超快电子转移和抑制的非辐射电子-空穴复合，这导致长寿命电荷参与析氢。光致动力学过程主要受能隙和边界供体和受体状态之间的非绝热耦合的影响。此外，通过第一性原理计算揭示了 PM6/PCBM 异质结处的析氢位点，这表明反应活性在很大程度上取决于 H 吸附位点。三个苯环连接处的C原子（C666）的活性远低于一个五边形环和两个苯环连接的C原子（C665）。尽管如此，通过对相邻的 C665 原子进行预氢化。这项工作详细揭示了 PM6/PCBM 异质结的新光物理和光化学性质，并为基于有机供体-受体异质结的光催化材料的性能改进提供了有用的视角。