本論文利用攪拌水熱法改變參數合成二氧化鈦，以刀刮及熱壓方式於ITO-PEN上製作二氧化鈦薄膜電極，討論二氧化鈦顆粒及薄膜的物理性質及應用於半導體敏化太陽能電池之研究。XRD分析顯示，在水熱溫度270℃、時間4h 、及攪拌速率300 rpm合成之二氧化鈦，主要的結晶結構為銳鈦礦。SEM分析指出，溫度270℃水熱4h 300 rpm之樣品，顆粒較大且團聚現象不明顯。經由UV-Vis實驗得知，改變水熱參數對二氧化鈦臨界吸光波長的影響不大，臨界吸收波長約380-390 nm，二氧化鈦能隙約為3.26-3.18 eV。在270℃水熱4h 300 rpm下製備之樣品，FT-IR顯示較低的IR吸收度，PL光譜顯示較弱的螢光強度，推測條件合成的TiO2有較高的結晶性，電子再結合速率變慢。藉由熱壓80℃100 MPa下製備二氧化鈦薄膜，純P25表面平整性良好，孔隙度較小，而P25混摻270℃水熱4h 300 rpm之樣品，平整性較差，孔隙度較大，有利於染料及電解液有效擴散。光電轉換效率影響，純P25光電轉換效率為2.91%，P25混摻270℃水熱4h 300 rpm之樣品(7:3) 光電轉換效率為3.69%，有效提升光電轉換效率。 In this thesis, effects of operating parameters of hydrothermal approach with stirring on the synthesis and physical properties of titanium dioxide particles were studied. The synthesized TiO2 particles were then subjected to plastic anodes based on ITO-PEN substrates by doctor blade and hot compression methods for application in dye sensitized solar cells.
UV-vis analysis indicated the synthesized TiO2 particles exhibited threshold wavelength around 380-390 nm, corresponding to bang gap energy of 3.18-3.26 eV. XRD analysis showed that anatase form was the predominant crystal structure of the prepared TiO2, and no rutile form appeared. However, the as-synthesized samples at 210℃ yielded trace brookite structure, and it disappeared as the temperature increased to 230℃. The hydrothermal samples synthesized at 270℃ and 300 rpm for 4h displayed the least IR absorption and PL intensity, which may be attributed to a high crystallization.
Under hot compression at 80 ℃ and 100 MPa, TiO2 films from pure P-25 illustrated more flat surface with low porosity, on the contrary, those comprising P-25 and synthesized TiO2 (7:3) explored more rough surface with large porosity, which was beneficial for dye solutions and electrolytes to permeate therein. The photo-to-electricity conversion efficiency effectively enhanced from 2.91% to 3.69% as 30% P-25 was replaced by hydrothermal TiO2 synthesized at 270℃ and 300 rpm for 4h.