Facile synthesis of hierarchical structure Bi2S3/TiO2 heterojunction and enhancing light-harvesting performance

Abstract

The microstructure of the photo-anode has prominent effect on the photoelectric performance of solar cells. A facile one-step hydrothermal method was used to synthesize TiO2 photo-anode with double-layer hierarchical structure. The saturated NaCl solution was added in precursor solution which promoted the formation of hierarchical TiO2. By controlling the reaction time, TiO2 hierarchical rod-flower structures with different morphologies were obtained. Bi2S3 nanomaterials were grown on TiO2 to form Bi2S3/TiO2 heterojunction. The optical and electric performance of Bi2S3/TiO2 has been greatly improved compared with the pure TiO2. The morphology and structure of the samples were carried out by FESEM, TEM, XRD and XPS. The optical and electrical properties were tested by optical absorption spectroscopy and electrochemical workstation. The results show that Bi2S3 widens the optical response range of the heterojunction and improves the carrier's separation efficiency. The bottom TiO2 nanorod provides a channel for the rapid transmission of electrons, and the upper flower-like TiO2 provides multitudinous adsorption sites for the deposition of Bi2S3. Meanwhile, it can also play a role in scattering the incident light and increase the absorption of light. This research work provides ideas for the subsequent preparation of photo-anode materials with high absorption and light scattering capabilities, and provides possibilities for its application in many aspects.