Silver Doped Tin Oxide for Enhanced Perovskite Solar Cells: A DFT and SCAPS-1D Study of Electronic, Optical, and Photovoltaic Properties

This work employs first‑principles density functional theory (DFT) calculations with device simulations to systematically explore the effect of Ag substitution in SnO 2 (Ag-SnO 2 ) on its electronic, optical, and photovoltaic properties as an electron transport layer (ETL) for tin‑based perovskite solar cells (PSCs). DFT calculations within the GGA-PBE + U framework, we reveal that Ag substitution significantly narrows the band gap and modifies the electronic and optical properties, while SCAPS‑1D simulations, under standard AM1.5G illuminations, were used to evaluate device performance and band alignment with CsSnI 3 perovskite absorber, confirming improved charge transport. Optical results show that Ag-SnO 2 exhibits stronger visible‑light absorption and higher conductivity compared to undoped SnO 2 . Device performance was assessed using SCAPS‑1D simulations under standard AM1.5G illumination. Compared to pristine SnO 2 with a power conversion efficiency (PCE) of ∼7.70 %, Ag-SnO 2 improves the photovoltaic performance, yielding an optimized efficiency of 12.00 %. Ab initio molecular dynamics simulations (AMID) further verify dynamic stability at 300 K, with Ag-substituted systems exhibiting superior thermal robustness. These results demonstrate that Ag substitution effectively alters ETL, which enhances photovoltaic performance in lead‑free tin-based PSCs.