Deposition of thin layers of CZTS by sol-gel route via spin-coating

Abstract

This work focuses on the development of Cu2ZnSnS4 (CZTS) thin films by chemical sol gel via spin-coating for photovoltaic applications. CZTS thin films were developed using metal salts of copper II chloride dihydrate (CuCl2, 2H2O), zinc(II) chloride (ZnCl2), tin II chloride dihydrate (SnCl2, 2H2O), and thiourea (CS(NH2)2) respectively as precursors of copper, zinc, tin and sulphur dissolved in a solvent consisting of a mixture of ethanol and distilled water (30 % ethanol and 70% water). Monoethanolamine (MEA) was used as a stabilising agent. The characterisation techniques used were X-ray diffraction (XRD), Raman spectroscopy and UV–visible spectroscopy (UV–vis). DRX analysis shows that the samples possess the CZTS kesterite phase with a preferential orientation in the (112) direction. This result is confirmed by the Raman spectrum of the samples. Optical characterisation indicates that the layers have a relatively high absorption coefficient (greater than 104 cm−1) in the visible spectrum with a gap energy equal to or close to the optimum value of 1.5 eV.These kesterite-type CZTS samples with good structural and optical properties are likely to fulfil sought-after functionalities as absorber layers for photovoltaic applications.