Tin–Lead Perovskite Solar Cells with Enhanced Reverse Bias Stability

We address reverse bias instability in tin–lead perovskite solar cells by introducing Cr/Cu bilayer electrodes in their electron-selective contacts, which raise thermal breakdown voltage from −7.6 V to −14.5 V. Chromium prevents catastrophic device failure by mitigating hotspot shunting, being chemically stable against I2 formed during reverse bias stress.