Single-Source Vapor-Deposited Cs₂AgBiBr₆ Thin Films for Lead-Free Perovskite Solar Cells

Lead-free double perovskites have been considered as a potential environmentally friendly photovoltaic material for substituting the hybrid lead halide perovskites due to their high stability and nontoxicity. Here, lead-free double perovskite Cs₂AgBiBr₆ films are initially fabricated by single-source evaporation deposition under high vacuum condition. X-ray diffraction and scanning electron microscopy characterization show that the high crystallinity, flat, and pinhole-free double perovskite Cs₂AgBiBr₆ films were obtained after post-annealing at 300 °C for 15 min. By changing the annealing temperature, annealing time, and film thickness, perovskite Cs₂AgBiBr₆ solar cells with planar heterojunction structure of FTO/TiO₂/Cs₂AgBiBr₆/Spiro-OMeTAD/Ag achieve an encouraging power conversion efficiency of 0.70%. Our preliminary work opens a feasible approach for preparing high-quality double perovskite Cs₂AgBiBr₆ films wielding considerable potential for photovoltaic application.