The Synthesis Of TiO₂ Mesoporous Spheres, MoS₂/C And The Applications To Fiber-shaped Dye Sensitized Solar Cells

Dye sensitized solar cells (DSSC) as a light-to-electricity transform device, due to its low cost, simple production process and so on has become one of the hottest research areas in the fields of material science, physics and chemistry. The cell efficiency of DSSC are higher than 12%. Compare to traditional flat DSSC, Fiber-shaped dye sensitized solar cells (FDSSC) is light and flexible, weaving capability and can integrate into other device due to its shape.In this paper, we prepared TiO2 mesoporous spheres (MSs) and fabricated photoanode of FDSSC by electrophoresis deposition (EPD) technique and synthetise MoS2/C as counter electrode materials for FDSSC.the main contents are as follows:1. The TiO2 mesoporous spheres (MSs) was prepared by a two-step synthesis: hydrolysis and then solvothermal treatment. The TiO2 mesoporous spheres (MSs) are composed of anatase TiO2 nanocrystals (10-20 nm) together to form larger secondary particles (600-800 nm). In the visible wavelength,TiO2 nanoparticles have a weak light scatter effect. Thus a scattering particles are incorporated to scatter red and near infrared lights on photoanode. However scattering particles with large size usually have a low surface area and weak in enhancement of loading dye, thus limit of the cell efficiency. The use of TiO2 MS with abundant mesopores promote light scattering and the accessible surface for dye loading insure the photon-to-current conversion efficiency of DSSC. Complex TiO2 MSs were deposited on a Ti thread using an electrophoresis deposition (EPD) technique as working electrodes of the FDSSC. The thickness of the TiO2 MS film can be controlled by altering EPD time in a constant voltage. Electrochemical impedance spectroscopic measurement demonstrates the film thickness-dependent photovoltage performance of the FDSSC. The total conversion efficiency of the FDSSC achieves 3.80% through optimizing the thickness of the film.2. Hydrothermal growth of thin-layered molybdenum sulfide-carbon nanostructured films on stainless steel wire directly as counter electrode for fiber-shaped dye-sensitized solar cells. Pt wire are usually used as counter electrode for FDSSC. However Pt is rare and expensive. Thus its need to find a proper counter electrode material to replace Pt. Due to its graphene analogues and electrocatalytic activity, MoS2 have attracted considerable attention in the past few years. MoS2 is a typical layered transition metal sulfide and a hexagonal structure. Sheet of Mo atoms is between two hexagonally packed sulfur layers, the three stacked atom layers (S-Mo-S) is bond by covalent and the force between sandwiches is van der Waals force. In the paper, MoS2/C hybrid material was synthesized by hydrothermal. Form the SEM images we can find that the smooth surface of the wire was coated by MoS2/C wholly and uniformly. MoS2/C hybrid spheres are composed by nanosheets. The large surface area are better for reduction of I3- ion on the counter electrode. FDSSC based on MoS2/C CE have a better performance due to a better electrocatalytic activity improving the I3- reduction on the MoS2/C electrode. FDSSC fabricated with MoS2/C CE have a better performance than that with pt wire CE, The total conversion efficiency of the FDSSC with MoS2/C CE achieves 6.56%.