Theoretical investigations of all inorganic Cs2SnI6 double perovskite solar cells for efficiency ∼ 30 %

Non-toxic and air-stable Cesium tin (IV) halide (Cs2SnI6) is a promising alternative to lead halide perovskite for photovoltaic applications. This study reports the extensive analysis of vacancy-ordered Cs2SnI6 perovskite as an efficient light harvester sandwiched between the n-ZnO electron transport layer (ETL) and different p-type metal oxides, namely CuBi2O4, Cu2O, CuAlO2, and NiO, hole transport layers (HTL), using SCAPS-1D software. Various physical parameters, viz. thickness, defect density (bulk and interfacial), and charge carrier concentration of different layers for the device architecture of FTO/ZnO/Cs2SnI6/HTL/Au, are systematically investigated along with the effect of parasitic resistance, work function, and operating temperature in the quest for best device performance in terms of photoconversion efficiency (PCE). The effect of DC biasing voltage is analyzed using C-V characteristics to understand the spatial charge distribution, absorber doping profile, and junction built-in potential. The frequency-dependent admittance was studied using simulated C-f characteristics to give an insight into the defect and the conductance. The Cesium tin (IV) halide (Cs2SnI6) based device optimized with CuBi2O4, Cu2O, CuAlO2, and NiO HTLs has shown PCE of 28.18 %, 29.72 %, 29.43 %, and 29.33 %, respectively.