Preparation of TiO2/Bi2S3 Composite Photo-Anode Through Ultrasound-Assisted Successive Ionic Layer Adsorption and Reaction Method for Improving the Photoelectric Performance

One important component of modern thin film solar cell designs is the photo-anode. TiO2 is the most common photo-anode material. However, TiO2 has no response over its wide band-gap to most of the visible light spectrum. Semiconductor coupling can improve the photoelectric conversion efficiency of TiO2 thin film photo-anodes. In our study, TiO2 arrays were coupled with the narrow band gap material Bi2S3 to form a TiO2/Bi2S3 composite. The Bi2S3 was deposited by successive ionic layer adsorption and reaction method (SILAR), then the effect of the number of deposition cycles on the composite film performance was studied. The as-obtained samples were characterized by x-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy and photo-electrochemical measurements. When the number of deposition cycles reached 10, the composite film showed the best optical and electrical properties. To improve the film performance, the SILAR method was modified with an ultrasound-assist. Under the same deposition cycle number (3 and 5), the current density of TiO2/Bi2S3 by ultrasound-assisted SILAR method was larger than that with the SILAR method alone. During the ultrasound-assisted SILAR process, the high temperature and high pressure provide by ultrasound accelerated the formation of new nuclei and increased the ion diffusion rate in the reaction solution, thus forming more Bi2S3 materials.