Thermally co-evaporated ternary chalcogenide AgBiS2 thin films for photovoltaic applications: new route for AgBiS2 synthesis and phase investigation

Abstract

AgBiS₂ films have recently garnered considerable interest for photovoltaic applications because of their optimal bandgap and high absorption coefficient. Nevertheless, their fabrication has been confined to solution-based processes, which limits their scalability and makes the production of large-area devices challenging. This paper presents the successful fabrication of phase-pure AgBiS₂ thin films using a thermal co-evaporation technique and their application in thin-film solar cells. The fabrication process utilized a compositional engineering approach that involved thermal co-evaporation of the precursor powders of Ag₂S and Bi₂S₃. Initial optimization experiments were conducted to determine the optimal Ag/Bi composition and crystallinity. It was found that thin films with a 1 : 1 Ag : Bi ratio post-annealed at 200 °C for 10 minutes exhibited the most favorable microstructure with high crystallinity. Consequently, a notable power conversion efficiency of 1.52% and an open circuit voltage of 346 mV were achieved. These findings pave the way for the production of AgBiS₂ thin-film solar cells using the thermal co-evaporation method for both research settings and commercial applications.