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. © 2024 The Royal Society of Chemistry.