Structural and Optical Annealing Route-Dependent Properties of CZTS Thin Films Grown by One-Step Electrodeposition with Free Annealing Sulfurization for Photovoltaic Application

Abstract

In the electrodeposition-anneal processes, the as-deposited film presents a deficiency of S which makes sulfurization inevitable. In this paper, an electrolyte was used for elaborating Cu2ZnSnS4 thin films with free annealing sulfurization onto indium-doped tin oxide-coated glass substrates for solar cell applications. For a one-step elaboration of CZTS thin films, a potentiostatic process has been adopted, and the deposition potential effect has been studied. The prepared samples were treated by annealing at different temperatures and subsequently were considered for structural and morphological properties with the aim to comprehend the growth behavior and to promote the film characteristics. X-ray diffraction (XRD) patterns showed the characteristic peaks at (112), (200) and (224) planes, which correlate with a Kesterite thin film structure and another phase impurity. The uniform area of the film and the grain size transformation of the particles relative to annealing temperature was investigated using scanning electron microscopy and the XRD analysis. From the optical study, the gap energy Eg was enlarged with changed annealing temperature in the range of 1.7–1.48 eV.