Absorber Enrichment and Its Implication on the Performance of Lead-free CsSnI3 Perovskite Solar Cells (PSCs) - A 1D-SCAPS Study

One-Dimensional Solar Cell Capacitance Simulator (1D-SCAPS) and n-i-p planar configuration have been employed for the simulation of the caesium tin iodide (CsSnI3)-based perovskite solar cell (PSC) with titanium (IV) oxide (TiO2) and copper thiocyanate (CuSCN) as the electron and hole transport materials respectively. The results obtained for the initially modeled PSC compared well with similar devices in the literature but marred with high recombination rate. As such, the defect density in the CsSnI3 absorber was varied from 1013 cm-3 to 1017 cm-3 and enriched with SnCl2 (additive) and Br−(dopant) respectively. This strategy ensured a reduced concentration of Sn4+ vacancy (VSn) in the CsSnI3 absorber with improved carrier lifetime and diffusion length beyond 0.05 ns and 1.1µm by a magnitude of the order of 103 and 102 respectively for the enriched CsSnI3 –based PSC. For the optimized PSC, we recorded VOC=1.289 V, JSC=32.60 mA.cm-2, FF=83.56% and PCE=35.12%.