A comparative study of Cu2ZnSnS4 thin films growth by successive ionic layer adsorption–reaction and sol-gel methods

Abstract Owing to the high natural abundance and non-toxicity of all the constituents, the copper–zinc–tin–sulfide compound has been attracting attention in recent years for the production of cheap solar absorber materials. Solution-based low-cost approaches are being developed for the deposition of this compound. In this comparative study, we have investigated Cu 2 ZnSnS 4 thin films prepared by using successive ionic layer adsorption–reaction and sol-gel methods. X-ray diffraction studies indicated the polycrystalline nature of the films. No secondary phases were observed. The sol-gel grown Cu 2 ZnSnS 4 film was found to have smaller crystallite size and higher micro-strain and dislocation density values. Phase purity and good crystalline quality of the studied films were proved through the Raman studies. From the scanning electron microscopy images, sol-gel grown Cu 2 ZnSnS 4 film was found to have more homogenous and smooth morphology. Possible chemical formula of the films was determined. The optical absorption of the sol-gel grown film covered a wider wavelength range by means of absorbing more visible photons. The optical band gap values were estimated to be 1.45 and 1.40 eV for the successive ionic layer adsorption–reaction and sol-gel grown samples, respectively. It was concluded that both methods are effective and can be used to produce high-quality Cu 2 ZnSnS 4 thin films for cheap and green solar cell applications.