Structural, Topographical and Optoelectronic Properties of ZnIn2S4 Thin Films Deposited from Dual Source Using Aerosol Assisted Chemical Vapour Deposition (AACVD) Technique

Abstract

The ZnIn2S4 (ZIS) thin films have been successfully developed from a homogeneous toluene solution of dithiocarbamate complexes of zinc and indium with formula [Zn(S2CNCy2)2(py)] (1) and [In(S2CNCy2)3].2py (2) via aerosol assisted chemical vapor deposition (AACVD) technique. Deposition experiments were carried out at 500oC in an inert atmosphere of argon gas on FTO substrate. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and Raman spectroscopy have been used for the determination of phase purity, surface topography of the uniformly distributed particles and oxidation states of the elements present in thin films. Further UV-visible spectrophotometry elucidates that the thin films absorbs in entire visible region and give estimated band gap energy of 2.37 eV. The photoelectrochemical (PEC) response in terms of linear scan voltammetry (LSV) provides a photocurrent density 2.27 mA.cm-2 at 0.7 V vs Ag/AgCl/3M KCl using 0.05 M sodium sulphide solution under AM 1.5 G illumination (100 mW.cm-2). The LSV results are further reinforced by electrochemical impedance spectroscopy (EIS) that gives charge transfer resistance (Rct) value of 5.7 x 104 Ω under dark conditions and reduces to 3.7 x 104 Ω under illumination.