Preparation Of TiO₂ Composite Photo-anode And Application In Dye Sensitized Solar Cell

TiO₂ nanomaterials have been gained comprehensive attention in photocatalyst,sensor,water photolysis and dye sensitized solar cells?DSSCs?due to its excellent properties and its significant application.In recent years,composite photo-anode composed of TiO₂nano-materials with different dimension possesses high electron transfer rate as well adequate dye molecule loading,which has expected to replace the conventional monolayer Ti O₂nano-structure as the electrode materials for a new generation of solar cells and become one of the hot topic in the field of materials science.Hence,carrying on the research of composite TiO₂ photo-anode has a great meal to improve the conversion efficiency of the DSSCs.In this thesis,the preparation and properties of photo-anode in DSSCs were particularly studied.Combining electrostatic spinning technique,solvothermal method and two-step anodic oxidation method,the disordered one-dimensional Ti O₂ nanofibers?NF?,hierarchical TiO₂ NF and highly ordered Ti O₂ nanotube?NT?arrays were successfully fabricated respectively.On this basis,the fabricated one dimentional Ti O₂ nano-materials were used as electrode materials for the composite structure TiO₂ photoanode and successfully applied in DSSCs.Besides,the photo-to-electric properties of solar cells based those composite photoanodes have been studied in detail.The main experimental and innovative results are as follows:1.Preparation,regulation and application in solar cells of Ti O₂ NF.Via the electrostatic spinning technique,the TiO₂ NF film with different diameter,different thickness were successfully prepared by using the mixed spinning solution containing titanium tetraisopropanolate,polyvinylpyrrolidone,acetic acid glacial and absolute ethanol.The influence of the spinning speed,film fomation time and other factors to the fabrication of TiO₂ NF have been studied.Finally,the as-prepared TiO₂ NF membrane was used as the photoanode in DSSCs,simultaneously,the influence of the compact layer in the solar cells based on TiO₂ NF was investigated.The results indicated that when the spinning rate is 2.0ml/h,the spinning efficiency and quality is the best.The as-fabricated TiO₂ NF membrane under different spinning process has a significant influence on the performance of DSSCs.When the thickness of NF membrane is around 20?m,we found that the solar cell with champion efficiency 6.8%was achieved while when the compact layer was introduced the highest efficiency reached to 7.7%.Besides,when using a large area of NF membrane as the photoanode of the device,the photoelectric conversion efficiency reached to 3.93%,almost close to 4%.2.The controllable synthesis,characterization and its application prospects of the hierarchical structure of TiO₂ coated TiO₂ NF and TiO₂ coated SnO₂ NF.The hierarchical NF were successfully obtained through two step method which containing electrostatic spinning technique and solvothermal method with titanium tetraisopropanolate,stannic chloride pentahydrate,potassium titanium oxalate as raw materials.The content of water in the solvothermal process was used to control the morphology of coated TiO₂ layer,so as to realize the controllable morphology of coated TiO₂ nano-structure.The experimental results suggest that when the content of water reached 9 ml,the morphology of coated TiO₂ nanorods grown on the surface of the TiO₂ NF is the best.At last,series characterization methods,such as the FE-SEM?field emission scanning electron microscope?,XRD?X-ray diffraction?,TEM?transmission electron microscope?methods were used to characterized the morphology,component,phase structure of the as-prepared hierarchical NF.At last,the hierarchical structure of TiO₂ coated TiO₂ NF was applied in the DSSCs.3.Fabrication and application of highly ordered TiO₂ nanotube?NT?based photoanode.Through traditional two-step anodic oxidation method,the Ti O₂ NT arrays was prepared and successfully peeled off from the high purity Ti foil and transfer to the FTO substrate to prepare the TiO₂ NT-based DSSCs.We systematically explored the affect of the location of the nanotubues to the DSSCs.It was found that by adjusting the location of the ordered TiO₂NT in TiO₂ nanorods particles and designing different composite photoanode could further enhance the conversion efficiency of the photovoltaic devices.Eventually,when the TiO₂ NT was placed between the TiO₂ nanorods membrane,the conversion efficiency of the champion DSSCs is up to 8.31%,which is the highest among other composite photoanode based devices.