Effect of film thickness on structural, morphological, and optical properties of Cu2ZnSnS4 thin films prepared by sol–gel spin coating

Thin films of copper zinc tin sulfide (CZTS) have been synthesized on glass substrates at various thickness layers by change in number of layer from 3, 5 and 7 layers using sol–gel spin coating deposition technique. SEM photos were demonstrated for different thickness layer at constant temperature 280 °C. According the EDX analysis thin films exhibit nearly stoichiometry with 1.1 and (0.5–0.8) atomic ratio Cu/(Zn + Sn) and Cu/Zn, respectively. XRD pattern of the prepared CZTS films Show that the films have relatively high intensity peaks at 28.5° for 3 layer and 29.8° for 5 layers of 2θ value corresponding to (112), (220) and (312) phase, respectively. As the thickness layer of the synthesized CZTS films increases to 7 thickness layer, the film structure tends to be amorphous at the same temperature 280 °C, so the films were annealed to temperature 360 °C and 400 °C for a better crystallization state. The optical band gab is found in the range 1.5–1.8 eV and observed to decrease with thickness layer increasing. Additionally, the effect of the annealing temperature on the morphology and the energy gap for a film of 7 layer thicknesses at various temperatures from 280 to 400 °C was performed.