| Summary: | 碩士 === 崑山科技大學 === 材料工程研究所 === 100 === TiO2 paste prepared by ball milling was coated onto ITO-PEN plastic substrates by doctor blade and mechanical compression techniques to form TiO2 photoanodes of dye sensitized solar cells with platinum counter electrodes. The influence of ball milling time, pressure and temperature of mechanical compression, and vauuum pretreatment on the characteristics of titanium dioxide films and perfromance of the DSSCs was investigated in this study. Commercially available P25 and home-made TiO2 with various particle sizes were used as precursors.
Without compression, increasing ball milling time can increase OH group quantity and reduce the particle size of TiO2, causing a more flat surface of TiO2 films and a higher photo-to-electricity conversion efficiency. With compression, there exists an optimum ball milling time and compression pressure for high conversion efficiency because a close compact film structure would retard the percolation of dye solution.
With a compression pressure of 100 MPa at room temperature and a ball milling time of 10 min at 150rpm yields the highest photo-to-electricity conversion among the parameters evaluated for P25 TiO2. For a home-made TiO2 with larger particle size (around 90 nm), the optimum ball milling time and compression presure were 60 min and 100 MPa, achieving the highest converison efficiency. Heat compression at 80℃ can significantly enhance the photo-to-electricity conversion efficiiency when compared with those of 60 and 100℃. A 20 min vacuum pretreatment can improve the film property via reduction of water molecules within the film. At high photovoltage region, the electron lifetime decreases with increasing photovoltage according the open circuit volatge decay measurement.
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