A Comparative SCAPS-1D Study of Lead-Free CsSnCl₃-Based Perovskite SCs Employing Different ETLs

Cesium tin chloride (CsSnCl₃) has drawn considerable interest as a non-toxic absorber candidate for next-generation photovoltaic devices, offering an attractive combination of affordability, thermal robustness, and competitive conversion performance suitable for clean-energy deployment. In the present work, the photovoltaic behaviour of CsSnCl₃-based SCs was numerically examined using the SCAPS-1D software. Three distinct device stacks were constructed by varying the ETL, such as WS₂, C₆₀, and ZnSe, while keeping CBTS fixed as the HTL. To establish optimal operating conditions, the influence of absorber thickness, carrier doping concentration, and bulk defect density was examined alongside the corresponding parameters of the ETL and HTL, with attention paid to four output metrics: PCE, J_SC, V_OC, and FF. Simulation outcomes confirmed that the choice of ETL exerts a pronounced influence on overall device behaviour. Peak conversion efficiencies of 22.09%, 19.94%, and 21.80% were obtained for the WS₂, C₆₀, and ZnSe-based architectures, respectively. Supplementary investigations addressed the role of series and shunt resistance, Quantum Efficiency (QE), C–V response, operating temperature, interface trap states. The Mott–Schottky characteristics, J-V profiles, and carrier recombination dynamics are also investigated. The numerical outcomes obtained here were benchmarked against earlier reports on CsSnCl₃-based devices to evaluate the extent of improvement and the prospects for long-term operation. Taken together, the findings put forward several refined and competitive architectures for high-performing, lead-free CsSnCl₃ Solar Cells (SCs), advancing the broader effort toward sustainable and economically viable photovoltaic platforms.