Lithium and sodium ion Co-doping: A promising strategy for enhancing the performance of Cs2AgBiBr6 perovskite solar cells

The non-toxic perovskite Cs 2 AgBiBr 6 presents impressive photovoltaic performance and stability, offering a lead halide-free alternative for solar cells. Overcoming challenges related to thin-film preparation and its intrinsic indirect bandgap, we leverage the synergistic effect of co-doping with lithium ions (Li + ) and sodium ions (Na + ) to enhance perovskite solar cells (PSCs). Improved carrier transport in Cs 2 AgBiBr 6 films, facilitated by the diffusion of Li + , significantly enhances the photovoltaic conversion efficiency (PCE). Systematic exploration of various doping ratios identifies the optimal co-doping ratio, resulting in a remarkable PCE increase to 5.02 % and a short-circuit current of 6.56 mA cm −2 . Ion doping not only tunes the material's band gap but also adjusts the energy level arrangement within the device layers. Impressively, the PCE of co-doped PSCs experiences only a 16.8 % decline after 60 days in an unencapsulated environment, underscoring its outstanding stability. This work provides a rational design for double-ion co-doping experiments, enhancing PSC performance and offering valuable insights for the future development of PSCs.