Structural and optical properties of cadmium sulfide thin films on flexible polymer substrates by chemical spray pyrolysis technique

Cadmium sulfide (CdS) films were deposited on polymide (PI) plastic substrate by chemical spray pyrolysis technique at substrate temperature in the range (300–375 °C) in 25 °C steps. The effects of substrate temperature on the structural and optical properties of the films were studied.Characterization of structural properties was carried out by X-ray diffraction (XRD). The XRD results confirmed proper phase formation of the CdS structure.These also revealed that the CdS films have a hexagonal structure and the crystallite size increased with increasing film temperature.The root mean square roughness of the films was measured by atomic force microscopy. This quantity increased as the film temperature did.The optical transmission measurements by UV–Vis spectrophotometer determined the energy gap of the CdS films on the PI plastic substrate. The optical band gap values of CdS thin films slightly increased as the film temperature did, and it was found to be in the range of 2.42–2.48 eV.