Research On High Efficiency And Durability Of Dye-sensitized Solar Cell

As the third-generation solar cell, Dye-sensitized solar cell (DSC) has been attracting more and more attention from researchers due to its high photoelectric conversion efficiency, simple procedure, low cost, rich raw materials and environmental friendliness. So far, small sized and large-scale DSC fabricated with Ruthenium-complex dye and electrolyte based on organic solvent has achieved the efficiency of over11%and9%, respectively. However, liquid electrolytes based on organic solvents always suffer from leakage and evaporation after long-term outdoor use, leading to performance degradation of DSC. To solve this problem, developing high stable quasi-solid and ionic liquid electrolytes is very necessary. The research content of this thesis is mainly about quasi-solid and ionic liquid electrolytes of DSC.In order to improve the wettability and full filling between polymer quasi-solid electrolyte and anode, in this study, we synthesized the copolymer P(VAc-co-MMA) based on PVAc’s good solubility and high viscosity and PMMA’s good liquid-absorbent ability and solubility in polar solvents. Then the novel quasi-solid electrolyte (or polymer gel electrolyte, PGE called for short) based on acetonitrile (ACN) or3-methoxypropionitrile (MPN) solvent was prepared. The addition weight percentage of copolymer was optimized and the effect of the addition of TiO2nanoparticle was investigated systematically. Using the best PGE based on ACN, the QS-DSC achieved a high photovoltaic conversion efficiency of9.40%, which reached about96.8%of the value for the DSC based on the liquid electrolyte under100mW cm-2. Subsequent results revealed that our QS-DSC had a better stability because it could maintain96.7%of its initial efficiency after long-time (1000h) exposure to simulative sunlight. Furthermore, for the first time, the large-scale QS-DSC was fabricated by screen-printing of PGE, other than the traditional vacuum injection method which was infeasible for the viscous gel electrolyte. Finally, our5cm×7cm QS-DSC sub-module achieved a conversion efficiency higher than4%.Under the existing production process of large-scale parallel DSC, the application of quasi-solid electrolytes is limited due to the sealing problem, although it has very high efficiency. Ionic liquid is more suitable for large-scale parallel DSC due to its non-volatility, good chemical stability, wide electrochemical window etc., especially it can be used by vacuum injection method. In this work, the binary ionic liquid electrolyte based on PMII/EMISCN was developed and the various factors affecting the photoelectric conversion efficiency of large-scale parallel DSC were investigated. The highest efficiency of more than4%was achieved under the optimal conditions. The stability of DSC was tracked by Ⅰ-Ⅴ measurement under outdoor lighting and alternately heating and freezing. The results showed that large-scale DSC based on the ionic liquid electrolyte has good stability, which laid the foundation for the industrialization of DSC.Finally, a new organic dye with D-π-A structure was designed, synthesized and applied into DSC. The effect of dye’s structure on the photoelectric conversion efficiency of DSC was discussed.