Photocurrent hysteresis related to ion motion in metal-organic perovskites

Perovskite solar cells have attracted considerable attention in the photovoltaic field for their high efficiency achieved in a short period of time. However, hystersis behaviour was often observed during the photocurrent-voltage measurement causes uncertainty in evaluation of photovoltaic efficiency. In this letter, we report a systematic investigation on the cause of hysteresis via series of TiO2 based planar heterojunction structured perovskite solar cell devices. The results reveal organic cation ions, such as the commonly employed CH3NH (3) (+) or HC(NH2) (2) (+) , play critical role on the observed hysteresis effect above the 298 K via interaction with iodide. We further suggest an efficient hole/electron transport in devices can inhibit such hysteresis behavior. Our conclusion sheds light onto the underlying hysteresis mechanisms, and proposes possible solutions to overcome the issue, which offers guidelines for future development of perovskite devices.