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

Abstract Monoclinic α‐Ag 2 S 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‐Ag 2 S 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‐Ag 2 S thin films. Ultrafast terahertz (THz) conductivity measurements reveal that photogenerated charge carriers undergo efficient band transport, with room‐temperature mobility of ≈ 150 cm 2 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‐Ag 2 S thin films with a mobility of ≈ 35 cm 2 V ‐1 s ‐1 , demonstrating their potential for flexible optoelectronics. This study provides a facile synthesis route for high‐quality, large‐area α‐Ag 2 S thin films with good charge transport properties, relevant for their integration into optoelectronics and wearable electronics.