二氧化鈦奈米管陣列與複合結構在染料敏化太陽能電池之應用

Abstract

染料敏化太陽能電池(Dye-sensitized solar cell, DSSC)是目前極具發展潛力的新一代有機太陽能電池。其中光電極表面形貌是影響效率的主因之一，期望利用二氧化鈦奈米管一維陣列結構改善電子傳輸而提升效率且未來發展可饒式元件具有較高的穩定性。 本論文中，含乙二醇,氟化銨及含水之電解液以陽極氧化處理法，於鈦板製備二氧化鈦奈米陣列(TNAs)及其複合結構(TNWs/TNAs)薄膜層上。實驗中由電壓、時間及攪拌對於結構變化關係可推論其形成機制並利用其變化製作相同厚度薄膜，但不同形貌之二氧化鈦光電極。進而探討不同電壓時間,產生不同結構TNAs及TNWs/TNAs。進而應用於染料敏化太陽能電池光轉換效率影響。 由光電轉換效率及可見光光譜儀檢測在相同膜厚(12μm)，奈米線複合結構染料吸附量較僅奈米管結構來的多，透過提升吸附染料而提高光電流密度，而有較好的光電轉換效率。於30伏特電壓下製備8小時之二氧化鈦複合結構染料吸附相對純奈米管結構有21%的差異且轉換效率達η=1.85%,其中電流密度由3.80提高至5.27 (mA/cm2)

Dye-sensitized solar cell (DSSC), a new generation solar cell, has the potential to be widely used due to its advantages of low cost, compatibility for flexible devices, and enhanced performance with temperature. Specifically, the morphology of TiO2 film is one of the major factors affecting the conversion efficiency. Among various structures, TiO2 nanotube has great potential due to the highly ordered could provide a direct transport route and higher stability for flexible device. In this study, a TNWs/TNAs hybrid structure was first fabricated using a one-step method by anodizing a titanium foil in electrolytes consisting of NH4F and H2O, under different voltage and processing time. The evolution and the mechanism of TNWs/TNAs hybrid structure prepared by using mechanical stirring were examined and proposed. The DSSC performance of TNWs/TNAs was measured and compared to TNAs and conventional TiO2 nanoparticle film. Based on the I-V characteristics and dye absorption measurement by an UV-visible spectroscopy, nanowires in the TNWs/TNAs (12 贡m) hybrid structure enhance the surface area and improve the redox couple diffusion in TiO2 electrode to raise the photocurrent, resulting in enhanced conversion efficiency. For TNWs/TNAs hybrid structure (30V, 8 hours), the conversion efficiency and Jsc are 1.85%, 5.27 mA/cm2, compared to 1.04% and 3.81 mA/cm2 in a TNA only film. The 44.3% improvement in conversion efficiency can be attributed to the enhanced dye adsorption (21%) and better electron transport in TNWs/TNAs compared to TNAs only. Overall, TNWs/TNAs films show great potential to be a simple and flexible DSSC.