非绝热分子动力学模拟A位阳离子对钙钛矿热载流子弛豫的影响  

A-site Cation Effects on Hot Carrier Relaxation in Perovskites by Nonadiabatic Molecular Dynamics Simulations

作　　者：贺进禄 龙闰 方维海[1] HE Jinlu;LONG Run;FANG Weihai(College of Chemistry,Key Laboratory of Theoretical&Computational Photochemistry of Ministry of Education,Beijing Normal University,Beijing 100875,China)

机构地区：[1]北京师范大学化学学院理论与计算光化学教育部重点实验室

出　　处：《高等学校化学学报》2020年第3期439-446,共8页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:21573022,21688102,21590801,21520102005)资助~~

摘　　要：钙钛矿具有优异的光学和电学性质,近年来成为太阳能电池领域的研究热点.大量实验报道钙钛矿热载流子弛豫时间变化顺序为CsPbBr 3>MAPbBr 3(MA=CH 3NH 3)>FAPbBr 3[FA=HC(NH 2)2],但A位阳离子(Cs+,MA+,FA+)对弛豫快慢的影响机制仍不明确.采用基于含时密度泛函理论的非绝热动力学方法研究了上述3种钙钛矿热电子和热空穴的能量弛豫动力学,计算得到的热载流子弛豫时间与实验结果吻合.结果表明,A位阳离子通过静电和氢键作用影响其与无机Pb—Br骨架的电子-振动耦合,使非绝热耦合强度遵从FAPbBr 3>MAPbBr 3>CsPbBr 3的变化趋势,进而使热载流子弛豫时间尺度变化趋势与之相同,表明合理选择A位阳离子可以优化钙钛矿太阳能电池的性能.In recent years,perovskites have become a research hotspot in the field of solar cells due to their excellent optical and electrical properties.A large number of experiments reported that hot carries relaxation times follow the trend CsPbBr 3>MAPbBr 3(MA=CH 3NH 3)>FAPbBr 3[FA=HC(NH 2)2].However,the underlying mechanism of the A-site cation(Cs+,MA+,FA+)effects on the relaxation time remains unclear,the hot electrons and holes relaxation of the three perovskiteswere investigated using time-domain density functional theory combined with nonadiabatic molecular dynamics.The obtained time scales agreed well with experiment.This is because A-site cation affects electronic-vibrational coupling with the inorganic Pb—Br framework via electrostatic interaction and hydrogen bond,leading to the strength of nonadiabatic coupling decreasing from FAPbBr 3 to MAPbBr 3,to CsPbBr 3.As a result,the hot carrier relaxation times decreases as the same trend.The study suggests that rational choice of A-site cations provides an excellent strategy to the optimize the performance of perovskite solar cells.

关 键 词：钙钛矿 A位阳离子 热载流子能量弛豫 非绝热动力学 含时密度泛函理论 

分 类 号：O641[理学—物理化学]