Direct deposition of Sn-doped CsPbBr3 perovskite for efficient solar cell application

Abstract

All inorganic carbon-based planar perovskites, particularly CsPbBr₃, have attracted considerable attention due to their excellent stability against oxygen, moisture, and heat for photovoltaic utilization. However, the power conversion efficiency of carbon-based planar CsPbBr₃ perovskite solar cells is mostly low, primarily because of the inferior film quality with undesirable crystallization and narrow light absorbance ranges. Herein, we develop a novel direct deposition approach combined with Sn doping to achieve highly efficient and stable carbon-based Sn-doped CsPbBr₃ perovskite solar cells. Mass-scale Sn ion-doped CsPbBr₃ perovskite powder was effectively synthesized and characterized via a facile strategy by adding hydrohalic acid in the CsBr, PbBr₂ and SnBr₂ precursor in a dimethyl sulfoxide solution. Moreover, using the as-synthesized CsPbBr₃ and Sn-doped CsPbBr₃ perovskite powder, PSCs were obtained via effective direct thermal evaporation. A smooth, constant and pinhole-free perovskite film was achieved with a configuration of FTO/TiO₂/Sn:CsPbBr₃/carbon. PSCs based on Sn:CsPbBr₃ as an absorber and carbon as the HTM achieved an impressive power conversion efficiency of 8.95% compared to 6.87% for undoped CsPbBr₃; moreover, it displayed admirable stability in an open-air atmosphere for an operational period of about 720 h without a noticeable negative result. The introduction of the Sn ion may advance the interface extraction of charge between the electric transport layer to the absorber layer and absorber to the carbon electrode. Accordingly, the Sn ion doping on CsPbBr₃ during the synthesis phase and the direct evaporation paves a novel approach for intended photovoltaic applications.