High-efficiency tin perovskite solar cells by the dual functions of reduced voltage loss and crystal regulation

Abstract

Environment friendly tin perovskite solar cells (TPSCs) have become a promising candidate due to their low toxicity and similar electronic configuration to lead counterparts. However, the easily generated defects due to the Sn2+oxidation and poor morphology originated from rapid crystallization are both barriers for tin-based devices in the enhancement of photovoltaic performance. Here, phenethylammonium chloride (PEACl) is introduced for post-treating FASnI3 films, which plays dual roles in adjusting film topography and passivating defects in bulk and interface of films. First, the film morphology can be improved by eliminating SnF2 impurities. In addition, a small amount of two-dimension perovskite can be formed in the films, inducing preferred orientation in secondary crystallization, well-matched energy level, and effective defect passivation. Finally, the FASnI3-based devices with PEACl treatment obtained a champion conversion efficiency of 11.63% with an average value of 10.76%, along with the obvious enhanced open circuit voltage and fill factor. In contrast, the pristine FASnI3 devices range from 6.92% to 9.40% with an average value of 7.96%. This work not only deepens our understanding of the suppression of defects in tin-based perovskites but also paves a facile way to ameliorate film morphology and interfaces to fabricate promising tin perovskites and devices.