氧化鋅奈米片的製備及其在染料敏化太陽能電池之應用

Fabrication of ZnO nanosheets and their application in dye-sensitized solar cells

蔡季洋(Chi-Yang Tsai)

指導教授 ： 余琬琴

國立臺北科技大學/工程學院/有機高分子研究所/碩士(2011年)

https://doi.org/10.6841/NTUT.2011.00030

摘要

氧化鋅是常用於製作染敏太陽能電池的陽極材料之一。氧化鋅的能帶結構與二氧化鈦相似，但擁有較大的電子遷移率，且能形成多種奈米結構。本研究以電化學沉積法製備二維氧化鋅奈米片結構，並將其製成染料敏化太陽能電池的工作電極。探討的因子包括鍛燒溫度、鍛燒時間與膜厚，鍛燒溫度有高低二個不同的溫度，即400℃和150℃，高溫鍛燒的時間固定為1小時，低溫鍛燒的時間則是從1 至36小時。
研究結果顯示，電化學沉積所得的奈米片是由氧化鋅前驅物構成，該奈米片大多直立於基板上，且相互連結形成網狀結構。經高溫鍛燒(400℃、1小時)後，該前驅物轉化成氧化鋅，而且奈米片上出現許多微小的孔洞。此多孔結構具有高的比表面積，而且直立的奈米片利於電子的傳輸，適合應用於染料敏化太陽能電池。結果顯示氧化鋅薄膜厚度對電池效率有顯著的影響，在膜厚為27 μm時，電池效率可達2.91%。
在低溫鍛燒方面，為了決定最佳的鍛燒時間，我們先固定膜厚(15 μm)，變化鍛燒時間。結果顯示最佳低溫鍛燒時間為24小時，在此薄膜厚度(15 μm)下，光電轉換效率可達3.34%。接著，我們固定鍛燒時間(24小時)，改變膜厚。結果顯示，最佳膜厚為21 μm，光電轉換效率可達3.84%。未來可望將此低溫製程應用於軟性基板，製成可撓式染敏太陽能電池。

關鍵字

染料敏化太陽能電池 ； 電化學沉積 ； 氧化鋅 ； 奈米片 ； 鍛燒溫度

並列摘要

Many studies have already been reported on the use of ZnO nanostructures for the fabrication of photoanodes for dye-sensitized solar cells (DSSCs). ZnO is a wide-band-gap semiconductor similar to TiO2, but has higher electronic mobility and can be produced in a wide variety of nanostructures. In this study ZnO nanoporous films were prepared by using the electrochemical deposition method and fabricated into DSSC photoanodes. The as-deposited films were composed of precursor nanosheets and required a calcination process to convert the precursor into ZnO before dye adsorption. The factors investigated included calcination temperature, calcination time and film thickness. Two different calcination temperatures were used, i.e., 400℃and 150℃. The calcination time at 400℃ was maintained at 1 hour, while the calcination time at 150℃ was varied from 1 to 36 hours.
The results show that the as-deposited precursor nanosheets were roughly vertically aligned with the glass substrate and formed a connecting network with space between them. Calcination at 400℃for 1 h not only converted the precursor into ZnO, but also generated numerous through pores on the nanosheets. Such a structure should be favorable for photoanode construction, because the porous nanosheets provide a relatively large surface area for dye adsorption, and the vertically standing nanosheets give a direct conduction pathway for electron transport. The film thickness of ZnO was found to have a significant effect on the performance of the resulting DSSCs. Peak conversion efficiency of 2.91 % was obtained with a film thickness of 27 μm.
In order to determine the optimal calcination time at 150℃, the calcination time was varied from 1 to 36 h, while the thickness of the ZnO nanoporous film was maintained at 15 μm. A calcination time of 24 h was found to be optimal, and the highest conversion efficiency achieved with the 15 μm film was 3.34%. In order to further improve the conversion efficiency, the effect of film thickness on cell efficiency was investigated. The highest conversion efficiency of 3.84% was obtained at a film thickness of 21 μm.

並列關鍵字

dye-sensitized solar cells ； electrochemical deposition ； ZnO ； nanosheet ； calcination temperature

參考文獻

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