Electrical properties of sprayed CuInS2 films for solar cells Original Research Article

CuInS2 films and superstrate configuration ZnO/CdS/CuInS2 solar cells were prepared by cost-effective spray pyrolysis technique using the Cu/In molar ratios of 0.9, 1.0 and 1.1 in spray solution. Appropriate metal chlorides and thiourea were used as starting chemicals to prepare the absorber layer. XRD, scanning electron microscopy, current–voltage, capacitance–voltage and frequency-swept admittance spectroscopy methods have been used to characterize sprayed absorber and solar cell. It has been shown that the carrier concentrations in CuInS2 absorber layer is close to 1017 cm−3 and VOC temperature dependent curve extrapolated to gives VOC(0) of 1.06 V. The columnar microstructure and small size of crystallites in sprayed films supposed to be responsible for inferior output characteristics of sprayed solar cell as FF=37%. According to the frequency-swept capacitance measurements the junction with lowest energy losses is formed with the absorber deposited from In-rich solution.