Revealing the Role of Interfaces in Photocarrier Dynamics of Perovskite Films by Alternating Front/Back Side Excitation Time-Resolved Photoluminescence

In perovskite communities, there still remain ambiguities in analysis of time-resolved photoluminescence (TRPL) decays especially under simplified interface conditions. We observed distinctive PL decays of the same perovskite film upon separate excitation from front/back side. By considering a diffusion–recombination model embedding surface recombination velocities (SRVs) at both sides of perovskite films, we quantified the crucial role of interfaces in photocarrier dynamics. We subsequently proposed a strategy by alternating front/back side excitation to derive parameters of carrier dynamics, especially allowing quantitative separation of the front- and back-side SRVs. Our strategy circumvents concerns on batch-to-batch inconsistency of perovskite film samples and reliance on accurate knowledge of charge carrier extraction efficiency in conventional TRPL-based measurements, as well as overfitting issues raised by full analysis and simulation of photocarrier dynamics. Our work suggests a reliable way leading to further fundamental investigations into a myriad of perovskite materials.