Surface Modification of Mesoporous TiO2 with Potassium ion Enhances Photo-Voltage in Perovskite Solar Cell

Trap induced non-radiative recombination is thought to be responsible for hysteresis and voltage loss in perovskite solar cells. Compared with interface or surface, bulk perovskite crystal has higher tolerance with trap state. Hence, interface engineering to enhance perovskite based device performance is particularly important to reach theory limitation. Here, we found that the modification of mesoporous TiO2 with KI is an effective way to reduce trap density at the interface between electron transporting layer and perovskite layer. The introduction of KI has no effect on perovskite morphology or charge carrier extraction, but the photo-voltage of devices is increased after KI treatment.