Impact of carrier extraction on photoinduced phase segregation of mixed-halide perovskites

Photoinduced phase segregation (PHS) poses a significant challenge in the practical utilization of mixed-halide perovskites (MHPs) for photovoltaic applications. In this Letter, we investigate the behavior of PHS within operational photovoltaic devices, extending beyond the conventional focus on single-layer MHPs. Our research explores the influence of carrier extraction on PHS by employing various charge transport layers (CTLs) in combination with perovskite films, utilizing photoluminescence (PL) characterization, mainly reflected through the time-dependent PL redshift. Furthermore, we observe that photovoltaic devices capable of efficient carrier extraction exhibit enhanced photoinduced stability during regular operation conditions such as short-circuit operation, as compared to open-circuit conditions. Our findings reveal that efficient photogenerated carrier extraction from the perovskite film mitigates the occurrence of PHS. This work underscores the significance of carrier extraction by CTLs in achieving the efficiency and stability of MHP-based photovoltaic devices.