Slow Response of Carrier Dynamics in Perovskite Interface upon Illumination.

The current-voltage hysteresis, as well as performance instability of perovskite solar cells (PSCs) under working condition, is serving as the major obstacles toward their commercialization, while the exact fundamental mechanisms to these issues are still in debate. In this study, we investigated the slow variation of photogenerated carrier dynamics in (FAPbI3)0.85(MAPbBr3)0.15 perovskite interface under continuous illumination. Different response behaviours of carrier dynamics in perovskite interfaces with and without hole transporting layer, Spiro-OMeTAD (Spiro), were systematically studied by time-dependent steady-state and time-resolved photoluminescence (PL). It was demonstrated that light-induced defect curing process is dominantly responsible for the carrier dynamic evolution for perovskite interface without Spiro, while both defect curing process and mobile ions migration should be account for the dynamic response of perovskite interface contact with Spiro. When contacted with Spiro, energy band curvature evolution in perovskite interface induced by ion migration would decrease the hole transfer rate from perovskite to Spiro upon illumination. This research work can faithfully highlight the strong correlation of slow photo-response behaviours of perovskite interface with both light-induced defect curing and ion migration process, providing novel implications into the physical mechanism for the slow variation of PSCs performance under working condition.