Application Of The One-dimensional Conductive Synthetic Nanomaterials And The Dye-sensitized Solar Cells

The professor O’Regan and Gratzel reported the dye-sensitized solar cell (DSSC) for the first time in1991, after that widespread research interests have been focus on this field owing to their low-cost, flexibility and high efficiency. The basic light-to-power conversion process in DSSC is as follows. Under illumination, the electrons generated by photo-excited dye molecules are injected into the conduction band of the Tio2, and then diffuse through the oxide film and transport to the F-doped tin oxide (FTO) substrate, along with the charge recombination. Finally, electrons are collected at the substrate/TiO2interface and pass through the external circuit.In a high-performance DSSC, great light absorption and fast electron transport are indispensable. Light absorption is related to the mount of anode dye adsorption, the traditional nanoparticles (NPs) electrode have a large surface area to ensure dye adsorption and light harvesting. However, the electrons travel through the network of interconnected nanoparticles film by a random walk, which enhances the probability of recombination with oxidizing dye or I3ions inthe electrolyde. As a result, the amount of collected photo-generated electrons is reduced and the efficiency becomes depressed. Hence, how to ameliorate the transport of electrons across the NPs film becomes the major bottleneck of getting higher photoelectric conversion efficiency (PCE) of DSSC.In order to solve the electron transport problem, considerable efforts have been paid, for example, some researches have revealed that photoanode based on1D array films exhibit dramatically faster electron transport compared to standard NPs photoanode. The array films as new type anodes, which possess excellent electron percolation pathways and make vectorial electron transport along the nanowire or nanotube axis. However, these array films have insufficient surface area to ensure light absorption and enough photo-generated electrons, the PCE are still moderate. After the report of synthesizing nanoparticles/nanowires composites photoanode, superior conductivity carbon materials were introduced into Tio2nanoparticles films, which can ameliorate the electronic transmission problems and PCE. And it is worth mentioned that one dimensional Ag nanowires possess preferable electrical and thermal properties than carbon materials. If the metal Ag can be used in the DSSC, the transmission of photo-produced electronics in anode may be improved significantly, the conversion efficiency also be improved obviously.Encouraged by the above thinking, this paper start with improving electron transfer rate and photo-generated collection efficiency, carbon coated silver nanocables have been synthesized by hydrothermal and introduced into anodes, further enhance the PCE of DSSCs. At the same time, we study the reason of improve the performance of the cells by the one-dimensional structure. In this paper, the research content and the main research results are as follows:(1) We use silver nitrate, sodium sulphide, ethylene glycol, PVP, etc as the raw material to prepare the one dimensional silver nanowires. And then, the optimal preparation condition is obtained by changing the reaction condition such as solvent, addition amount of reactant. At the same time, the samples were characterized.(2) We use silver nitrate, potassium carbonate, distilled water etc as the raw material to prepare one dimensional nanocables. The reaction temperature, reaction time, reaction solvent are researched to ascertain the influence of the production morphology, finally the optimum preparation condition is obtained. Sample test result shows that the length of nanocable is15-20μm, the carbon shell is amorphous structure, and the diameter of the Ag core is about200nm.(3) Prepare the anode films of DSSC, and the cells performances are testedand analysed. The mass ratio of Ag nanowires with P25, Ag/C nanocables with P25are1%, the pastes are prepared according to this rate, after that the anode films are prepared and encapsulated into the cells, and then test the I-V characteristics at a different time, contrast the stability of the cells. Additionally, according to the different mass rates of the Ag nanocables with P25to prepare the slurrys, after test the I-V performances of encapsulated cells, the The optimal proportion is obtained under the highest conversion efficiency. Finally, the dye adsorption amount, electrochemical impedance test, stability test are analyzed and then we get:the introduction of nanocable can effectively speed up the electronic transport in the light anode film and light electron collection efficiency.