Inorganic charge transport layer for efficient Pb-free KSnI3 based perovskite solar cells: a theoretical study

Abstract The power conversion efficiency (PCE) of lead (Pb)-based perovskite solar cells (PSCs) is remarkably high; however, the toxicity of Pb poses a significant barrier to their commercial viability. In the current study, the effect of different charge transport layer (CTL) materials on the performance of the Pb free Sn-based (KSnI 3 ) PSCs has been studied by using SCAPS simulations. Tin oxide (SnO 2 ), zinc oxide, and titanium dioxide as electron transport materials, whereas spiro-OMeTAD, copper oxide (Cu 2 O), and nickel oxide as hole transport layer materials were iterated to achieve the optimum photovoltaic parameters. The photovoltaic parameters were optimized in terms of the active layer and CTL thicknesses, as well as the doping concentration, defect density, and interfacial defect density. Moreover, the impact of series and shunt resistance on the performance of PSCs is also investigated. The most efficient PSC with PCE of 21.75% was achieved with the device structure of FTO/SnO 2 /KSnI 3 /Cu 2 O. This efficiency is higher than previously reported KSnI 3 based-PSCs. The SnO 2 (ETL) and Cu 2 O were proven to be most efficient choices for the CTL materials. It was also observed that the carbon, nickel, and selenium can be a cost-effective alternative to gold for the rear contact. This study showcases how KSnI 3 with inorganic charge transport layers stands as a prospective stable PSC with the potential to deliver clean, and green renewable energy solutions.