Preparation of cubic ZnIn2S4 thin films through a tartaric-acid-assisted hydrothermal process

Abstract

Herein, cubic ZnIn₂S₄ thin films with a pyramid-like structure were successfully synthesized on FTO substrates by a tartaric-acid-assisted hydrothermal method. Tartaric acid was found to play an important role in the formation of cubic-structured films. In the absence of tartaric acid, hexagonal phases of ZnIn₂S₄ and In(OH)₃ were obtained. By properly monitoring the experimental conditions, including the reaction time and concentration of tartaric acid, ZnIn₂S₄ films with different morphologies were formed on the FTO substrates: the possible growth mechanism was proposed in this study. The as-prepared films were characterized by their XRD, SEM, TEM (HRTEM), and UV-vis absorption spectra. The UV-vis absorption spectra showed that the cubic structure has a bandgap of 2.3 eV, whereas the photoelectrochemical characterization guaranteed that the cubic ZnIn₂S₄ film is a potential material for producing hydrogen by splitting water using solar energy. It is hoped that this study could promote further interest in the design of controllable nanostructures and their potential applications in advanced fields.