Trap states, exciton properties and carrier dynamics in the multicomponent lead halide perovskites

Abstract Component engineering in perovskite (PSK) films has emerged as one of the most efficient approaches for improving their photovoltaic capacity and stability. However, the role of component engineering is complex and diverse, especially the related trap-state properties, exciton dissociation, and charge carrier dynamics, which require further investigation. Herein, various anions and cations such as FA + , Cs + , MA + , Br − , and I − are introduced into the Pb-based PSK precursor solution for synthesizing multicomponent Pb-based PSK films. And the influence of component engineering on the trap-state, exciton properties and charge carrier dynamics was investigated through temperature, time-dependent fluorescence, and optoelectronic characterizations. The multicomponent PSK of CsFAMA significantly passivates traps, especially shallow energy level traps. As trap density decreases, the exciton binding energy ( E b ) and polaron binding energy ( E p ) of CsFAMA decrease from 125.70 meV and 102.65 meV to 54.16 meV and 35.99 meV, respectively, which is beneficial for exciton dissociation and thus promotes charge separation and transport. The interfacial charge transfer efficiency between CsFAMA and charge transport layer is greatly improved. Additionally, appropriate component regulation is conducive to improving stability. Our findings elucidate that component engineering can passivate trap states in perovskite materials (PSK), promote exciton dissociation, enhance charge separation and transport, and effectively suppress charge recombination.