Investigation of nucleation and growth mechanism of Cu2ZnSnS4 absorber layer electrodeposition on Indium Tin Oxide coated glass

Abstract

In this paper, earth-abundant and environmentally friendly kesterite Cu2ZnSnS4 (CZTS) thin films are successfully synthesized by electrodeposition on Indium Tin Oxide (ITO) coated glass for photovoltaic application. For the first time, the electrochemical nucleation and growth mechanisms of the kesterite electrodeposition are investigated. Here, the electrochemical growth mechanism is studied and the diffusion coefficient D is calculated for different applied potentials. Our findings show that kesterite deposition occurs through progressive nucleation followed by the limited growth of diffusion of 3D hemispheric islands. Furthermore, it has been proven that the type of nucleation and growth is not influenced by the applied potential. Scanning electron microscopy, X-ray diffraction and UV–vis are used to characterize the physicochemical properties of the prepared samples. The morphological and crystallographic investigations reveal a different morphology and structure of the CZTS film deposited at different potentials for different times. Among the samples studied, the CZTS thin film prepared at −1.1 V for 60 min offers the best properties with 2.4 µm thickness after annealing at 450 °C.