The effects of thermal treatment on structural, morphological and optical properties of electrochemically deposited Bi2S3 thin films

Thin films of bismuth sulfide (Bi2S3) have been electrochemically deposited on indium-doped tin oxide substrates from aqueous solutions of Bi(NO3)3, ethylene diamine tetraacetic acid (EDTA) and Na2S2O3. The structural properties of the films were characterized using X-ray diffraction and high-resolution transmission electron microscopy analyses. The film crystallizes in an orthorhombic structure of Bi2S3 along with metallic bismuth. Thermal annealing of the prepared film in sulfur atmosphere improves its crystallinity and cohesion. The band gap values of the deposited film before and after annealing at 400 °C were found to be 1.28 and 1.33 eV, respectively.