The capacitive effect of inverted perovskite solar cell caused by the interface between perovskite layer and zinc oxide layer

Abstract

Because of the good passivation effect of PCBM on the perovskite surface, ion-migration-related phenomena are barely discussed in the inverted perovskite solar cells (PSCs). However, when applying the ZnO as electron transport material (ETM) to replace PCBM, the resulting PSC device exhibits J-V hysteresis to some extent. Here we compare the J-V performances of the inverted PSC devices using ZnO and PCBM as ETMs. We find that the use of the ZnO results in an obvious light soaking phenomenon and J-V hysteresis. While the use of PCBM leads to the elimination of the J-V hysteresis. The time-dependent photocurrent response and the capacitance-frequency (C–F) measurement suggest the existence of fast and slow ion migration in the MAPbI3 film. The activation energy (Ea) for the slow ion migration reduces under illumination, being the main reason for the J-V hysteresis for the ZnO-based PSC device. While PCBM passivates the slow ion migration, leading to the elimination of the J-V hysteresis.