Design of all-inorganic hole-transport-material-free CsPbI3/CsSnI3 heterojunction solar cells by device simulation

Abstract

The hole transport material (HTM)-free perovskite solar cells (PSCs) have attracted widespread interest due to enhanced stability and lowered cost as compared to the sandwich-type PSCs with an organic hole conductor. For the absorber layer, CsPbI3 has become a competitive candidate for its good chemical-components stability, excellent optoelectronic properties and most proper bandgap among inorganic halide perovskites. However, the power conversion efficiency of CsPbI3-based HTM-free PSCs is still much inferior to that of conventional ones. In this work, an all-inorganic-perovskite-heterojunction CsPbI3/CsSnI3 is proposed as the absorber and the HTM-free CsPbI3/CsSnI3 PSCs are investigated systematically through numerical simulation by using SCAPS-1D. Compared with the HTM-free PSCs employing a single CsPbI3 absorbing layer, the HTM-free CsPbI3/CsSnI3 PSCs have the extended absorption range and enhanced performance. The best cell efficiency is increased from 15.60% to 19.99% and from 13.87% to 19.59% for the cell with a back-front Au electrode and a back-front C electrode, respectively. It reveals that for the HTM-free CsPbI3/CsSnI3 heterojunction cells, C is a good choice for back-front electrode as it can achieve desirable cell performance with improved stability and lowered fabrication cost. These results indicate that the proposed HTM-free CsPbI3/CsSnI3 heterojunction cells are promising for photovoltaic applications.