Preparation and Characterization of Nano Structured Cu₂ZnSnS₂ (CZTS) Thin Film by Spray Pyrolysis Method for Photovoltaic Application

The nano structured Cu2ZnSnS4 (CZTS) were synthesised by ultra-sonication technique using the precursor solution at constant temperature. The precursor solution used to contain copper chloride [CuCl₂.2H₂O], zinc chloride [ZnCl₂.2H₂O], tin chloride [SnCl₄.5H₂O], and thiourea [SC(NH₂)₂). The precursor solution contains 50% of double distilled water and 50% of methanol as solvents then it kept under ultra-sonication for 3 hrs, then the required precursor material CZTS were synthesised by using spray pyrolysis technique. The physical and optical properties of CZTS material have been investigated by different techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, UV-visible spectroscopy and transmission electron microscopy (TEM). The formation of CZTS has been confirmed by XRD and formation of tetragonal phase with orientation along (112) direction with crystallite size varies from 15 nm to 45 nm. The band gap values of CZTS thin film were found about 1.43 eV by analysis of UV-visible Spectroscopy. Raman spectra are characterized by the main CZTS peaks at 332.01 cm¯¹, and weaker CZTS modes at 121.16 cm¯¹ and 179.11 cm¯¹. The SEM image shows formation of nano scale particulate clusters with size vary in the range of 16 nm to 35 nm. Energy dispersive spectrum (EDS) spectra were recorded in order to determine the elemental composition of the CZTS nano particles. A TEM image of the CZTS shows inter planar spacing (d-spacing) measured in the HRTEM is 0.31 nm corresponds to (112) family plane. The CZTS solar cell has conversion efficiency (η) is 15.5 %.