| Summary: | 碩士 === 明道大學 === 材料科學與工程學系碩士班 === 99 === This work was to examine effects of MWNTs content and type of TiO2 in catalytic layer, layer sintering temperature, thickness and layer engineering on performance of the MWNTs-assisted dye-sensitized solar cells（DSSCs）. The cells were fabricated by the following steps：First, prepare aqua solutions of mixing TiO2 photocatalyst powders（from two different producers, UR P25 or Degussa P25）with acetylacetone dispersant, Triton X-100 surfactant, and MWNTs. The aqua solutions were then spin-coated several times on ITO glasses to vary the thickness of the catalytic layer. The coated layers were followed by sintering in an air furnace and then sorking in N3 dye solution. The LiI electrolyte was then filled into space between catalytic layer and Pt-coated counter electrode to form DSSCs. The cell performance was measured by using a solar simulator, the transmission and structures of catalytic layer were characterized by SEM, EDS, OM, XRD, and UV-Vis, respectively. From the experimental results, the following conclutions can be drawn.
About effect of TiO2 type, the results show that a lower percentage of anatase phase in TiO2 powders（Degussa P25）may be the reason of producing cell with a greater short-circuit current (Jsc) and the cell efficiency.
The results also indicate that MWNTs content, thickness and layer engineering of the catalytic layer play important roles on cell efficiency. The best cell efficiency is essentially a compromise between probabilities of optoelectronic reactions and transferring the generated electrons. The function of MWNTs is basically to enhance the transferring efficiency of electrons after optoelectronic reactions. Under the prescent conditions, the best cell performance（1.86％）is under the following conditions: 0.1wt％ MWNTs content, 3 times of spin-coating （or 4.9 μm in catalytic layer thickness）, catalytic layer engineering by spin-coating the catalytic layer without MWNTs as the blocking layer between electrolyte and catalytic layer.
Regarding effect of sintering tempersture of the catalytic layer, it appeals that a higher sintering temperature results in a less porocity, so less dye adhesion and less contact opportunity of electrolye with ITO glass. The results indicate the highest tolerance sintering temperature（450℃）for ITO glass with catalytic layer could give a higher cell efficiency.
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