Chemical bath deposition and characterization of Cu2O-CuxS thin films

Cu-2 O-Cu-x S thin films have been deposited on glass substrate by chemical bath deposition technique. The films were obtained by depositing Copper Sulphide (Cu-x S) on Copper (I) Oxide (Cu-2 O) and then Cu-2 O on Cu-x S. The peak solar transmittance across the thin films were found to be < 40% and as low as 10%, and falls with energy into the infra-red region. The absorbance is higher near the UV and IR regions. Reflectance is < 20%. The band gap of both respective combinations is in the range of 2.19-2.32 eV and with film thickness 0.54 mu m-1.30 mu m. The extinction coefficient and refractive index are in the ranges of 5.41 x 10(-2) - 20.11 x 10(-2) and 1.60-2.60, respectively. Since the absorbance increases as one goes towards the IR region, the films could be useful in solar control (providing cool interior) in tropical regions.