Investigation of Silver and Copper Doping on Antimony Sulfide Thin Films Obtained by Electrophoretic Deposition

In this work, we demonstrate the production of pure and doped Sb2S3 thin films by electrophoretic deposition (EPD). The consequences of silver and copper doping were evaluated by measuring the films’ structural and optoelectrical properties. Sb2S3 nanoparticles (NPs) were first synthesized in ethylene glycol and stabilized with polyethylenimine (PEI). Doped NPs were obtained thanks to silver or copper precursors added during the synthesis process. Orthorhombic Sb2S3 and extra AgSbS2 and CuSbS2 phases were identified by XRD after thermal treatment at 300 °C under vacuum. Metallic Sb impurities were also found for thermal treatment under 275 °C. UV–vis–NIR spectroscopy highlighted the optical properties of amorphous and crystalline thin films as well as the variation of optical band gaps by doping. Photocurrent measurement showed an increase in conductivity for doped thin films (by 3 in the dark and by 2 under AM 1.5 illumination). Adding silver or copper also brought a slower recombination of electron–hole pairs after switching the light off.