Photoanode Optimization And Photovoltaic Property Study On TiO₂Dye-sensitized Solar Cell

Due to the global environment pollution and impending exhaustion of fossil fuels, thedevelopment of solar cell industry is faster. Although silicon solar cells with high performancehave shared over ninety percent of the solar cell market, additional subsidies from nationalgovernment are still needed for large-area utilization due to the high cost. Moreover, thetraditional silicon solar cell industries in China are experiencing "double reverse" tradesanctions, which makes them more difficulty to survive. A possible way to solve thecontradiction between their performance and cost is to develop novel solar cells usingnanomaterials and nanotechnology with new characteristics, which is different from thetraditional bulk or thin film cells. Inorganic oxides are usually green and abundantsemiconductors and can be used to fabricate solar cells with low cost and high efficiency.In this thesis, we focus on dye-sensitized solar cells (DSSC). The TiO2nanorods arrayssynthesized by a hydrothermal growth method were used as abodes. We studied the influenceof rapid annealing, erosion, composition, and doping on the morphology and structure of TiO2nanorods and photovolatic performance of corresponding DSSC.1. The TiO2nanorods arrays were fabricated on the fluorine-doped tin oxide (FTO) galsssubstrates by a hydrothermal method. The length, diameter and their distribution of TiO2nanorods were controlled by changing reactant concentration, reaction time and introductionof TiO2seed layer. The growth mechanism of TiO2nanorods arrays was also explained. Thecrystallinity of TiO2nanorods was improved and the combination between TiO2surfaces withdye molecule was strengthened after a rapid annealing process. Moreover, the efficiencies oflight harvesting and electron injection and collection were improved with a result of higherphotovoltaic conversion efficiency of DSSC.2. The TiO2nanorods arrays were etched to study the influence of erosion onphotovoltaic performance. It was found that the light scattering effect was getting worseowing to the decrease of length and diameter of TiO2nanorods with increasing etching time.The current density and power conversion efficiency of DSSC were improved while TiO2nanorods fabricated with TiCl4were etched into nanotubes resulting in an increased surfacearea. 3. A new kind of composite anode structure composed of TiO2nanorods arrays with highelectron mobility and electron life and nanoparticle mesoporous film with high specificsurface area was designed and fabricated successfully. Resultly, a photovoltaic conversionefficiency of2.51%was obtained, which was higher than that obtained from pure TiO2nanorods DSSC (1.11%). By another surface treatment process with TiCl4, the DSSCefficiency based on such composite TiO2anode was further improved to3.25%.4. The TiO2nanorods arrays were doped with Sn to study the influence of doping onphotovoltaic performance. The X-Ray Diffraction (XRD) results showed that the TiO2nanorods preserved their single crystal structure. I-V curves displayed that short-circuitcurrent density and open circuit voltage were improved slightly, which demonstrated thatdoping maybe a possible way to improve the photovoltaic performance.