Influence of pH value on PbS thin films prepared by electrodeposition

PbS thin films were prepared on indium-tin oxide transparent conductive film glass substrates using a constant voltage cathodic electrodeposition method. The as deposited thin films were characterised by XRD, AFM and Fourier transform infrared spectrometer. The influence of pH value on the phase compositions, surface morphologies and optical properties of the films has been particularly investigated. Results show that cubic PbS thin films with oriented growth along (111) and (200) direction can be obtained at pH=2.4, deposition voltage=3 V, deposition time=20 min and adding EDTA as a complexing agent. The as deposited thin films exhibit a dense surface morphology. The compressive stress and optical bandgap of the PbS thin films first decrease and then increase with increasing the pH value, and the bandgap of the thin films is calculated to be 0.38-0.39 eV.