Design and Simulation of High-Efficiency CH₃NH₃PbI₃/CsSnBr₃-based Bilayer Perovskite Solar Cell

The aim of this research is to enhance the efficiency of a perovskite solar cell (PSC) designed with twc perovskite absorber layers (PALs). The higher bandgap (1.75 eV) cesium tin bromide (CsSnBr <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> ) perovskite material has beet used as the top active layer, and the lower bandgap (1.50 eV methylammonium lead halide (CH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> NH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> PbI <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> ) perovskit material has been used as the bottom active layer. To design precise bilayer device with proper band alignment, Spiro OMeTAD and ZnO have been used as the hole transport laye (HTL) and electron transport layer (ETL), respectively. Tc carry charge carriers to the external circuit, FTO and Ni hav been used as front contact and back contact, respectively. In this study, a comparison between CH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> NH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> PbI <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> -based single layer PSC and CH₃NH₃PbI₃/CsSnBr₃-based double-layer PSC has been done. The double-layer structure performs better as i covers a comparatively broad spectrum and reduces thermalization loss. For better performance of the bilaye structure, the thickness and doping concentration of both PALs have been varied to find the optimum value. After the optimization, this bilayer structure has achieved a maximur efficiency of $ 29.87%$.