Effect of thiourea on structure, morphology and optical properties of spray deposited CZTS thin films for solar cell applications

Abstract

<p>Cu2ZnSnS4 (CZTS) films of different Thiorea (SC (NH2)2) molarity were deposited by using simple chemical spray technique at substrate temperature 275°C. Analytical reagent Grade Copper chloride (CuCl2), Zinc chloride (ZnCl2), Tin chloride (SnCl4.5H2O) were used as Cu+ , Zn+ , and Sn+ ion sources respectively and thiourea (SC(NH2)2) (0.02, 0.04 0.06 0.08, and 0.1 M) was used as a Sion source. A set of five CZTS films was deposited using five different molarity of thiourea. The structure, Morphology, Elemental analysis and optical properties of these films were studied using X-ray diffratometer (XRD), Scanning Electron Microscopy (SEM) Energy Dispersive X-ray Analysis (EDX) and UV-Visible spectroscopy techniques respectively. The XRD spectra showed that all films are polycrystalline tetragonal structure with preferential orientation along (112) plane. The calculated crystallite size was increased with increase in thiourea concentration. Variations of optical band gap with thiourea molarity have been investigated using Tauc plots. SEM micrographs exhibits CZTS spherical granules regularly arranged with some void spaces. Purity of deposited films was investigated using EDX analysis. All the CZTS films exhibits higher absorption coefficient (𝛼 > 104) cm-1 and band gap in the reported range (1.2-1.53 eV) can be used as an absorber layer in solar cells.</p>