Optimising Lead-Free Cs₂BiAgI₆ Perovskite Solar Cells for enhanced performance and stability

Lead-free inorganic perovskite material Cs₂BiAgI₆ has shown remarkable environmental stability and photoelectric properties. This work examines the electrical characteristics of Cs₂BiAgI₆-based photovoltaic solar cells (PSCs), considering factors like operating temperatures, interface defect densities, absorber layer thickness, electron transport layers (ETLs), hole transport layers (HTLs), and doping densities. Based on our findings, Cs₂BiAgI₆ PSCs have a quantum efficiency that spans 80–90% in the 400–900 nm wavelength range. This significant efficiency highlights the possibility of using Cs₂BiAgI₆ in stable and eco-friendly perovskite solar cells on a large scale. Cs₂BiAgI₆ provides a viable substitute for silicon-based cells, which are limited by their instability and the dangerous nature of lead-containing perovskites. Our study's noteworthy 25.36% efficiency was attained with the FTO / Spiro-OMeTAD-PEDOT: PSS / Cs₂BiAgI₆ / TiO₂-ZnO / Metal Electrode combination. We assessed nine different structural configurations and improved the performance by adjusting the thickness, doping, and defect density of the perovskite absorber layer and addressing the effects of impedance in the ETL and HTL layers. These results provide theoretical direction for improving lead-free PSC performance and expanding their real-world use.