標題: 利用光電流與光電壓衰減方法研究不同管長奈米管染料敏化太陽能電池之電荷轉移動力學
Studies of Charge-Transport Kinetics in TiO2 Nanotube-based Dye-Sensitizer Solar Cells with Different Tube Lengths using Photocurrent and Photovoltage Decay Methods
作者: 林佳蓉
刁維光
應用化學系碩博士班
關鍵字: 染料敏化太陽能電池;二氧化鈦;電荷轉移動力學;奈米管;DSSC;ATO;Electron Transport;TiO2;nanotube
公開日期: 2010
摘要: 本論文主要在了解二氧化鈦奈米管的一維結構,是否有助於提升電子在半導體層的傳遞速度。因此我們選擇不同厚度的二氧化鈦奈米管薄膜(ATO)進行實驗,來探討此問題,並研究ATO的製程、染料吸附量和電解液厚度這些變因對於電子擴散速率的影響。 首先,在ATO製程間誤差的實驗中,我們發現製程條件相同、厚度相似、染料吸附量相似的ATO,其組成的DSSC在效率、擴散係數與電子生命期的結果皆相似。其次,在不同染料吸附量的實驗中,我們發現染料吸附量的增加造成DSSC開路電壓的上升,以及ATO表面覆蓋率的提高而使得電子生命期變長,但對於電子的擴散速率則無明顯影響。再者,在不同電解液厚度的實驗中,我們發現電解液厚度會改變ATO上的能階分布(DOS)分布與最低能態的位置,使的在電解液厚度的增加下,造成開路電壓的提升。同時電解液厚度會使DSSC在450 nm以前的IPCE值下降,導致短路電流有些許下降。最後,在不同ATO的長度的研究中,我們發現當ATO長度越長時,ATO的表面態分佈曲線越陡,同時ATO長度增加代表染料吸附量也隨之增加,造成有較多光電子注入二氧化鈦,使得最高表面態隨著ATO長度的增加而越靠近導帶。如此,使得電子在ATO上的去局限過程變得更為容易,也因此使擴散速率變得比較快。 我們認為ATO的微結構可能在成長過程中受到電場的作用力下進行有規則的排列,使得其表面能態分布造成改變,減少深層的局限能態,造成光電子去局限至導帶之間的能隙變小,也就是電子的擴散速率變快。因此二氧化鈦奈米管具備高長度的潛力,因為它在高長度時,亦具有高的電荷集合效率。
To understand how the anodic titanium oxide’s (ATO) microstructure affecting the charge transport processes on TiO2 surface, we modified various thickness of ATO and measured the photovoltaic properties with IV, IPCE, and charfe-transport kinetics with transient photocurrent and photovoltage methods. In addition, we also studied the effects of dye loading amount and thickness of the electrolyte layer on the performance of ATO-DSSC. The diffusion coefficients and electron lifetimes were found to be almost the same (within the standard deviation is ~10%) at similar length of the ATO film made by the same method. The dye loading amount of N719 on ATO surface influences the open-circuit voltage (VOC) and electron lifetime (□n), but it does not influence the electron diffusion coefficient (Dn). When we modified the thickness of the electrolyte layer, it alters the distribution of density of trapped states (DOS) and the potential of band edge of TiO2. However, the thickness of electrolyte does not affect the Dn of the ATO. It is important to understand the mechanism for the dependance of Dn on length of ATO when thicker ATO arrays generate higher photo-current densities. We found that Dn becomes faster on longer ATO under the same JSC. It means that the charge collection efficiency would become larger if the device is made of longer ATO arrays.
URI: http://140.113.39.130/cdrfb3/record/nctu/#GT079725541
http://hdl.handle.net/11536/45191
顯示於類別:畢業論文


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  1. 554101.pdf