Controlled synthesis and photoelectric application of ZnIn2S4nanosheet/TiO2nanoparticle composite films

Abstract

This paper reports the controlled synthesis of ZnIn₂S₄ nanosheet/screen-printed TiO₂ nanoparticle composite films by a facile hydrothermal method and demonstrates the photoelectric application of ZnIn₂S₄ nanosheets as potential inorganic sensitizers in semiconductor-sensitized solar cells. The ZnIn₂S₄ nanosheets with a thickness of about 20 nm and a lateral size of 2 μm were distributed not only on the surface but also in the interior of the TiO₂ nanoparticles, indicating a full contact between ZnIn₂S₄ nanosheets and TiO₂ nanoparticles. The ZnIn₂S₄/TiO₂ composite films demonstrated bandgap energy values ranging from 2.38–2.64 eV and their peaks can shift from the ultraviolet region to the visible region, compared with that of the TiO₂/FTO film (FTO: fluorine-doped tin oxide). The densities, thicknesses, morphologies of the ZnIn₂S₄ nanosheets could be controlled by adjusting the experimental parameters, including reaction times, temperatures and concentrations. The possible formation mechanism and growth process of the ZnIn₂S₄ nanosheets on the TiO₂ nanoparticles were discussed based on the experimental results. Furthermore, as a proof-of-concept, ZnIn₂S₄/TiO₂-based inorganic semiconductor-sensitized solar cells were fabricated by filling polysulfide liquid electrolyte into the electrodes and the device exhibited a reproducible photovoltaic response.