Strain Engineering for Enhanced Photovoltaic Performance of Lead-Free Cs2AgBiI6 Double Perovskite: Insights from Density Functional Theory

Abstract

This study investigates the photovoltaic potential of the lead-free double perovskite Cs₂AgBiI₆ using Density Functional Theory (DFT) with the GGA-PBE functional. We provide a comprehensive analysis of the material’s structural, electronic, optical, and photovoltaic properties. The results demonstrate that Cs₂AgBiI₆, with its stable cubic Fm3m structure, exhibits promising characteristics for solar cell applications, including a suitable band gap and strong light absorption in the visible spectrum. To further enhance the material’s performance, we explored the impact of triaxial strain ranging from − 6% to + 6%. The application of tensile strain led to significant improvements in key photovoltaic parameters. Specifically, the short-circuit current density (Jsc) increased by 6% under + 4% strain, reaching 29.39 mA/cm², while the power output (P) improved by 30% at + 5% strain, achieving 29.23 mW/cm². These enhancements highlight the potential of strain engineering as a strategy to optimize the optoelectronic properties of Cs₂AgBiI₆ for efficient solar energy conversion.