Coagulated SnO2 Colloids for High-Performance Planar Perovskite Solar Cells with Negligible Hysteresis and Improved Stability.

Organic-inorganic perovskite solar cells with a planar architecture have attracted much attention due to the simple structure and easy fabrication. However, the power conversion efficiency and hysteresis behavior need to be improved for planar-type devices where the electron transport layer is vital. SnO2 is a promising alternative for TiO2 as the electron transport layer owing to the high charge mobility and chemical stability, but the hysteresis issue can still remain despite the use of SnO2 . Now, a facile and effective method is presented to simultaneously tune the electronic property of SnO2 and passivate the defects at the interface between the perovskite and SnO2 . The perovskite solar cells with ammonium chloride induced coagulated SnO2 colloids exhibit a power conversion efficiency of 21.38 % with negligible hysteresis, compared to 18.71 % with obvious hysteresis for the reference device. The device stability can also be significantly improved.