| Summary: | 碩士 === 元智大學 === 化學工程學系 === 93 === This thesis is dedicated to make transparent ITO thin film with high conductivity using nanoparticles. Investigation includes two parts : (i) gold nanoparticles were prepared by either “salt reduction” or “seed-mediated growth”, and coated onto ITO substrate by self-assembly method and (ii) ITO nanoparticles prepared by sol-gel methods were used to make ITO films. In the first approach, the gold nanoparticles by “seed-mediated growth” method seemed to change in shape and size along the growth time. No steady state can be achieved. Therefore, the gold nanoparticles by “salt reduction” method, spherical shape of 16nm size, were assembed on ITO substrate which had been pretreated by silane (APTMS). Experiment results showed that gold nanoparticles aggregated with growing size and changing shape with assembly time. The cover layer of gold nanoparticles became ~50 nm size and formed homogenous closed layer packed eventually. After 5-hr assembly time, its transparency in visible light region reduced to around 64%; however, the sheet resistance fell from original 15 Ohm to 3 Ohm.
On the other hand, ITO sol-gel nanoparticles were prepared in either ethanol or acetylacetone solvent. The ITO sol-gel solution in ethanol is achromatic and transparent. After coating on glass substrate and subsequant treatment at high temperature, its transparency in visible region was above 90% and its sheet resistance was around 350 Ohm. The ITO sol-gel solution in acetylacetone had transparent yellow color. After coating and high-temperature treatment, its transparency in visible region decreased with coating thickness. With 8 spin-coating layers, its transparency in visible region was only 64% and its sheet resistance was around 440 Ohm. However, its transparency could be improved from 64 % to 92% if a two-step treatment procedure was used,which includes a high-temperature. oxidative sintering followed by a sintering in reducing environment. If we continue to increase coating times to sixteen, the sheet resistance can be reduced to 270 Ohm, but this conductivity is still not as good as the commercial ITO film made from sputtering method.
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