Corrosive Behavior of Silver Electrode in Inverted Perovskite Solar Cells Based on Cu:NiO_x

The stability issue of perovskite solar cells is the greatest bottleneck on the way to commercialization. Here, we report the degradation mechanism of perovskite solar cells (PSCs) with inverted structure of fluorine-doped tin oxide (FTO)/Cu:NiO_x/MAPbI₃/PC₆₁BM/Ag. The oxidative degradation of PC₆₁BM electron transport layer forms pinholes and leads to the water-catalyzed decomposition of perovskites. The formation of silver iodide confirms the iodine is from decomposition of perovskites. The instability of inverted PSCs based on Cu:NiO_x is owing to corrosive behavior of silver electrode. In addition, we find that a small amount of bromine doping in the perovskite material can delay the corrosion of the silver electrode. This paper demonstrates it is essential to deeply understand the degradation mechanism of the devices and a small amount of bromine doping is a feasible strategy to suppress the corrosion of the silver electrodes.