Novel multi-spray approach for preparing Cu₂ZnSnS₄ films for efficient solar photoelectrochemical water splitting

In this paper, a novel multi-spray approach was adopted and optimized to prepare high quality Cu₂ZnSnS₄ films. To achieve the Cu₂ZnSnS₄ phase under optimized conditions using this technique, a series of samples with different Cu:Zn:Sn:S atomic ratios were prepared and investigated using various characterization methods. X-ray diffraction (XRD) analysis indicated that the crystalline quality was strongly dependent on the Cu:Zn:Sn:S atomic ratios. In all cases, a pure Cu₂ZnSnS₄ kesterite phase structure with (112) orientation was obtained. All prepared films exhibited low transmittance (approximately 30 %) in the visible region. Electrochemical photocurrent tests showed that the films presented a cathodic photocurrent, thus confirming the p-type conductivity of the prepared films. Films deposited using a solution with the stoichiometric composition (Cu₂ZnSnS₄) exhibited excellent structural, morphological and electrochemical properties, with photocurrent density reaching up to 6 mA/cm².