Properties of CuInS2 thin films for solar cells prepared by spray pyrolysis

We prepared CuInS₂ thin films by spray pyrolysis and we characterized the films by X-ray diffraction, optical transmittance and electrical resistivity measurements in order to study optimum deposition parameters, such as the chemical composition of the solution and the deposition temperature. By observing the X-ray diffraction spectra we have determined that an appropriate deposition temperature is around 390°C with a starting solution containing a S/Cu ratio of 3.9 and a Cu/In ratio of 1.2. In this case, the material obtained shows good crystallinity, a band-gap around 1.45 eV and p-type conductivity around 2.5×10^-3 (ohm-cm)^-1 at room temperature. These properties are adequate for the material to be used in solar cells