In-situ perovskite solar cell carrier dynamics characterized by ultrafast photovoltaic spectroscopy (UPVS)

Understanding carrier dynamics in operational solar cells, i.e., under working conditions, remains a significant challenge. Establishing a direct correlation between carrier dynamics and solar cell performance requires an innovative approach that integrates the following key features: 1) in operando and in situ diagnostics, rather than conventional ex situ methods such as structural characterization by SEM, TEM, or XRD; 2) a focus on electrical rather than optical properties; 3) comprehensive carrier dynamics measurement with ultrafast time resolution, rather than limited and slower temporal ranges; and 4) a high-throughput screening capability. In this report, we employ a novel ultrafast photovoltaic spectroscopy technique to investigate the ultrafast carrier dynamics in >20% CsFAMAPbIBr perovskite solar cells by directly capturing the photocurrent with a time resolution of less than 40 picoseconds. This approach enables the characterization of carrier mobility and lifetime within in situ solar cells under operational conditions. Our findings reveal that the carrier transport mechanism is dominated by traps, a conclusion supported by the dependence of transport behavior on both electric field and temperature. This study represents a significant step toward advancing our understanding of carrier dynamics in operational solar cells, paving the way for more effective diagnostics and improved device performance.