Hydrogenated Cs₂AgBiBr₆ double perovskites: a sustainable lead-free route toward high-efficiency solar cells

Lead-based perovskite absorbers have an outstanding photovoltaic efficiency, yet be hazardous. Major concerns relate to the environmental safety and the durability of the devices in the long run. As an Outcome, a Cs2AgBiBr6-based double-perovskite material has emerged as a viable lead-free solution due to its chemical stability and reduced toxicity. Although they are not yet as efficient as traditional Pb-based perovskites, recent research, particularly studies on hydrogenation-induced bandgap tuning, indicates that they can be improved. In this study, we use the computer model SCAPS-1D to critically assess the performance of a hydrogenated Cs2AgBiBr6-absorber electrode supported in an inverted p-i-n model. A parameter sweep was performed in detail to investigate the influence of thickness and defect absorber density, concentration of doping of the hole transport layer. We also assessed the performance of popular electron transport layers, which are SnO2 and ZnO, to detect the best charge-extracting material to use in the proposed design. The optimized device configuration, using ZnO ETL, 0.4 μm absorber thickness, and better parameters of the HTL, provides a current density (short-circuited) of 20.87 mA/cm2, voltage(open-circuited) of 1.4523 V, fill factor of 85.50% and 25.92% total power conversion efficiency, respectively. These results demonstrate that optimizing the parameters leads to an increase in photovoltaic efficiency of lead-free double-perovskite solar cells. This paper demonstrates the potential of Cs2AgBiBr6 Absorbers as sustainable materials in future photovoltaic innovations.