FA离子重定向引起的电荷局域显著抑制了FAPbI3钙钛矿电子-空穴复合：时域从头算研究

本文利用从头算非绝热分子动力学结合时域密度泛函理论模拟，计算表明部分FA(FA=HC[NH₂]₂⁺)阳离子的重定向造成电子和空穴局域在不同位置，减小了非绝热耦合并抑制了原子运动，从而显著抑制了FAPbI₃的非辐射电子-空穴复合. 虽然慢的核运动同时增加了退相干时间，但是减小的非绝热耦合是影响电荷复合的主导因素，将电子-空穴复合的时间尺度延长至数纳秒，比原始的FAPbI₃激发态寿命长约3.9倍，与实验结果相符. 研究厘清了实验报导的FAPbI₃激发态寿命增加的机理，为设计高性能的钙钛矿太阳能电池和光电器件提供了合理的策略.

Charge Localization Induced by Reorientation of FA Cations Greatly Suppresses Nonradiative Electron-Hole Recombination in FAPbI3 Perovskites: a Time-Domain Ab Initio Study

Recent experiments report the rotation of FA (FA=HC[NH₂]₂⁺) cations significantly in-fluence the excited-state lifetime of FAPbI₃. However, the underlying mechanism remains unclear. Using ab initio nonadiabatic (NA) molecular dynamics combined with time-domain density functional simulations, we have demonstrated that reorientation of partial FA cations significantly inhibits nonradiative electron-hole recombination with respect to the pristine FAPbI₃ due to the decreased NA coupling by localizing electron and hole in different posi-tions and the suppressed atomic motions. Slow nuclear motions simultaneously increase the decoherence time, which is overcome by the reduced NA coupling, extending electron-hole recombination time scales to several nanoseconds and being about 3.9 times longer than that in pristine FAPbI₃, which occurs within sub-nanosecond and agrees with experiment. Our study established the mechanism for the experimentally reported prolonged excited-state lifetime, providing a rational strategy for design of high performance of perovskite solar cells and optoelectronic devices.