Cross Sectional Potential Profile Dependent on Device Architecture in Reverse Bias for Perovskite Solar Cells

A major challenge to the commercialization of perovskite photovoltaics is reverse bias degradation. While this issue stems from the forced current matching between shaded and illuminated cells, the mechanism driving this breakdown process is still poorly understood. Recent studies show that device architecture engineering has a significant impact on the reverse bias behavior of perovskite solar cells. Here we study the mechanisms of reverse bias degradation with a combination of methods, including scanning Kelvin probe microscopy (SKPM) and cross-sectional imaging. We show that the voltage drop across the device varies with device architecture, specifically hole transport layers, providing further insight to the structure-function relationships that contribute to reverse bias degradation. Furthermore, we address the effect of carrier transport and ion pile-up at the perovskite/charge transport layer interfaces. These experiments show that cross sectional SKPM is a powerful tool for probing degradation mechanisms, revealing the progression of both interfacial and bulk behaviors in real time.