Anomalously large interface charge in polarity-switchable photovoltaic devices: an indication of mobile ions in organic–inorganic halide perovskites†
It is proved that a large amount of mobile ions exist in organic–inorganic halide perovskites. The accumulated ions at the interface change the band bending of the semiconductor, leading to polarity-switchable photovoltaic devices. The interface charge significantly influences the function and performance of perovskite devices. The discovery of the interface charge has important implications for current–voltage hysteresis in perovskite solar cells.