Solution-Processed Wafer-Scale Ag2S Thin Films: Synthesis and Excellent Charge Transport Properties

Abstract

Monoclinic α-Ag2S is an intriguing member of transition metal sulfides with great potential for all-inorganic flexible optoelectronics and thermoelectrics. Fabrication of large-area, high-quality α-Ag2S thin films and understanding their charge transport properties are critical for device operations yet have remained largely unexplored. Here, a novel two-step, the solution-processed approach is reported to produce wafer-sized, highly crystalline α-Ag2S thin films. Ultrafast terahertz (THz) conductivity measurements reveal that photogenerated charge carriers undergo efficient band transport, with room-temperature mobility of ≈150 cm2 V-1 s-1 and a diffusion length exceeding 500 nm. Furthermore, introducing poly(vinyl alcohol) (PVA) as the rigid component into the aqueous silver thiolate precursor enables the synthesis of free-standing α-Ag2S thin films with a mobility of ≈35 cm2 V-1 s-1, demonstrating their potential for flexible optoelectronics. This study provides a facile synthesis route for high-quality, large-area α-Ag2S thin films with good charge transport properties, relevant for their integration into optoelectronics and wearable electronics.