Suppression of Oxidative Degradation of Tin–Lead Hybrid Organometal Halide Perovskite Solar Cells by Ag Doping

We present a simple and effective method for increasing the power conversion efficiencies (PCEs) and oxidative stability of tin–lead hybrid perovskite solar cells (PSCs). The Ag-doped PSCs with encapsulation retain 95% of their initial PCE after exposure to ambient air for 1000 h. Ag doping increases the grain size and reduces the thickness of amorphous intergranular films, thereby inhibiting the infiltration of oxygen into the perovskite crystals. A quantum mechanical simulation with density functional theory revealed that Ag doping increases the energy barrier to the adsorption of oxygen onto the perovskite surface. Ag doping also relaxes the microstrain in the perovskite, which suppresses the chemical interactions between O2 and the perovskite. We also verify that this method is also applicable to the tin-only perovskite for highly stable lead-free PSCs. We believe that these results open up the possibility of the use of various dopants to fabricate stable lead-free PSCs.