Preparation Of TiO₂Nanocrystalline And Nanorods For Application In Dye Sensitizatized Solar Cells

Energy is the basement of world development and economic growth, is thefoundation of the human society’s continuing development. To solve the problems ofenergy crisis and environmental pollution， looking for a renewable and greenalternative energy is the research focus and hotspot of the world. In this paper,westudy the working principles of the dye sensitized solar cells, working mechanism andthe restricting relationship of all the components in detail，use dye sensitized solar cellswhich intimate photosynthesis as the research object. Design and make up TiO₂thinfilm electrodes with different composition and microstructure, make solar cells bycombining with high molar extinction coefficient ruthenium dye C106, compare andevaluate the photoelectric properties and parameters of the cells using the technique ofUV-visible absorption spectroscopy and J-V curve, study further electrontransportation’s microcosmic dynamic mechanism in the cells adopting the techniquesof transient photocurrent decay and electrochemical impedance. The whole thesisincludes the following three parts:（1） Prepare TiO₂nanocrystals whose diameter are20nm by combining Sol-gelmethod and hydrothermal crystallization technology. Prepare different thickness ofmesoporous thin film electrodes by screen printing, through researching the influenceof mesoporous TiO₂thin film thickness on the performance of dye sensitized solarcells, we find that with the thickness of mesoporous TiO₂film increasing, short circuitcurrent density of the cells increases and the open circuit voltage decreases. As theelectrode surface area increases along with the film thickness increasing, more dyescan be adsorbed, thereby Optical trappingability is enhanced. However, the contactarea between the mesoporous thin film electrode and electrolyte and the course ofphotogenerated electrons to the current collector have also increased.（2） By using two-step hydrothermal growth system, prepare rutile single crystalTiO₂nanorods, whose mean diameter is30nm, and length is137nm, then mix withnanocrystal respectively in the proportion of0,5and10wt%to prepare sizing agent,make mesoporous thin film electrodes whose thickness is about7.6μm by screenprinting, sensitize and assemble a series of solar cells using C106dye. Further analysis finds that one-dimensional TiO₂nanorods can prolong electron’s lifespan, increase thediffusion length, reduce electron’s recombination rate in the TiO₂/electrolyte interface,effectively improve electron transmission performance of the cell, and then improvethe performance of the solar cells.（3）Using hydrothermal synthesis method, rutile TiO₂nanorod array can grow ontothe indium-tin oxide glass, and we can respectively get1.21μm and2.17μm high TiO₂nanorod arrays by controlling the growth time, prepare photoanode, combine withC106dyes and assemble cells. The results show that the one-dimensional TiO₂nanorods ordered array structure can effectively reduce the electron transport barrierwhich needs to overcome in the cell, improve electron transport performance andelectron collection efficiency, increase the photoelectric properties of dye sensitizedsolar cells.