Zn₂SnO₄ as a Novel Electron Transport Layer for Chalcogenide Perovskite Solar Cells: A SCAPS-1D Simulation Study

This study presents a simulation-based assessment of zinc stannate (Zn₂SnO₄) as a potential electron transport layer (ETL) for chalcogenide perovskite (CP) solar cells. Four CP absorbers: BaHfSe₃, BaZrSe₃, CaZrSe₃, and CaHfSe₃ were investigated using the SCAPS-1D simulation tool. To benchmark Zn₂SnO₄, conventional ETLs such as tin oxide (SnO₂) and titanium dioxide (TiO₂) were employed, with a 100 nm-thick nickel oxide (NiO) layer used as the hole transport layer (HTL) in all device configurations. Among the ETLs studied, SnO₂ achieved the highest power conversion efficiency (PCE), followed by TiO₂ and Zn₂SnO₄. Although Zn₂SnO₄ yielded comparatively lower efficiencies, ranging from 17.91% (BaHfSe₃) to 14.64% (CaHfSe₃), it demonstrated uniform performance across all absorbers. Combined with its high optical transparency, thermal stability, and electron mobility, Zn₂SnO₄ is positioned as a promising alternative ETL. Comparative analysis with previously reported simulations further underscores its potential in CP solar cell applications. Furthermore, device performance deteriorated significantly once the absorber defect density surpassed 10¹⁵ cm⁻³, due to enhanced non-radiative recombination. These findings offer valuable insights into CP solar cell optimization and support further experimental validation of Zn₂SnO₄-based architectures.