Precision Design of Lead-Free Sr3SbCl3 Perovskite Solar Cells: Role of Electron Transport Layers and Interface Optimization

Abstract

This work presents a systematic SCAPS-1D simulation of lead-free perovskite solar cells (PSCs) employing Sr3SbCl3 as a light-absorbing material. A comparative analysis of six electron transport layers (ETLs), CdS, SnS2, ZnSe, In2S3, WS2, and Zn(O,S) was performed based on conduction band alignment, carrier mobility, and interfacial compatibility. Among them, ZnSe, In2S3, and WS2 exhibited the most superior photovoltaic performance and were selected for detailed optimization. Key parameters, including ETL and absorber thickness, doping concentration, and bulk and interface defect densities, were systematically optimized to suppress recombination and enhance charge transport. The electric field distribution and Shockley-Read-Hall recombination were analyzed to elucidate the carrier lifetimes and recombination dynamics. The Au/Sr3SbCl3/WS2/FTO configuration achieved the highest power conversion efficiency (PCE) of 31.4%, outperforming ZnSe- and In2S3-based devices with PCEs of 30.92% and 30.93%, respectively. Notably, while all three configurations displayed identical open-circuit voltages (Voc = 0.958 V), WS2 provided superior short-circuit current densities (Jsc) and fill factors, attributed to optimal interfacial energetics and elevated electron mobility. This investigation highlights the significance of ETL selection and interface engineering in the advancement of stable, nontoxic perovskite devices that achieve efficiencies above 30%. This work establishes Sr3SbCl3 as a novel, environmentally benign, and sustainable alternative for next-generation perovskite photovoltaics.