摘要
Abstract
Perovskite solar cells have been a prominent focus in the field of photovoltaics in recent decades,owing to their exceptional performance:easy synthesis,and cost-effectiveness.The all-inorganic cesium-based perovskite CsPbBr3,known for its remarkable thermal stability,has become a star material in the field of optoelectronics due to its outstanding luminescent properties.Despite the high efficiency of lead-based perovskite solar cells,the toxicity associated with lead and the poor long-term stability of these devices remain significant barriers to their large-scale commercialization.As is well known,non-radiative electron-hole recombination significantly shortens the carrier lifetime,acting as a primary pathway for excited state charge to loss energy.This phenomenon directly affects the photovoltaic conversion efficiency and charge transfer performance of perovskite materials.Therefore,maximizing the reduction of non-radiative recombination energy loss in perovskite solar cells has become a crucial research focus.In this study,a systematic exploration is conducted by using a non-adiabatic molecular dynamics approach combined with time-dependent density functional theory to investigate the excited-state carrier dynamics of CsPbBr3 and its alloyed structures,CsPb0.75Ge0.25Br3 and CsPb0.5Ge0.25Sn0.25Br3.The study comprehensively analyzes the non-radiative electron-hole recombination scenarios and the mechanisms for reducing charge energy loss based on crystal structure,electronic properties,and excited-state properties.The research findings reveal that alloying with Sn/Ge can reduce the bandgap,increase non-adiabatic coupling,and shorten the decoherence time.The interplay of reduced quantum decoherence,smaller bandgap,and larger non-adiabatic coupling effectively decelerates the electron-hole recombination process.Consequently,the carrier lifetime of the CsPb0.75Ge0.25Br3 system extends by 1.6 times.Moreover,under the joint influence of Sn/Ge,the carrier lifetime of the CsPb0.5Ge0.25Sn0.25Br3 system extends by 4.2 times compared with those of the original system.The overall sequence follows CsPb0.5Ge0.25Sn0.25Br3>CsPb0.75Ge0.25Br3>CsPbBr3.This study underscores the significant influence of binary alloying of B-site metal cations(in the perovskite structure ABX3,where B-site refers to the metal cation)on the non-radiative electron-hole recombination of CsPbBr3.This research presents an effective alloying scheme that substantially prolongs the carrier lifetime of perovskites,offering a rational approach to optimizing solar cell performance.It lays the groundwork for the future design of perovskite solar cell materials.关键词
CsPbBr3/非绝热分子动力学/合金化/非辐射电子-空穴复合Key words
CsPbBr3/nonadiabatic molecular dynamics/alloy/nonradiative electron-hole recombination
