Introduction of LiCl into SnO2 electron transport layer for efficient planar perovskite solar cells

SnO2 has recently aroused huge attention as an electron transfer material for planar halide perovskite solar cells. Nevertheless, planar structure devices exhibit significant hysteresis behavior and low optical stability for their considerable trap states and high ultraviolet transmittance. In this study, LiCl was added to the SnO2 electron transport layer. As revealed from the results, adding LiCl could enhance the mobility of SnO2 film and promote the optical stability. Lastly, Li:SnO2 devices achieved high power conversion efficiency (PCE) of over 18% and steady-state PCE of 18.35%. Besides, they displayed prominent stability storage under dry conditions.