陽極氧化鋁奈米結構之抗反射特性於太陽能電池之應用

Antireflective Characteristics of Anodic Aluminum Oxide Nanostructures for Solar Cell Application

張躍馨(Yueh-hsin Chang)

指導教授 ： 張慎周

崑山科技大學/工程學院/電機工程研究所/碩士(2008年)

https://doi.org/10.6828/KSU.2008.00065

摘要

本論文主要為研究陽極氧化鋁(AAO)奈米結構之抗反射特性於太陽能電池之應用。理想下，太陽能電池希望可吸收到所有光波段的太陽光，以轉換成電能。然而，實際上卻有30 %以上的太陽入射光會被太陽能電池的表面反射出來，無法順利進入電池內部。因此，抗反射塗佈(Anti-reflection coatings，ARCs)膜或糙化結構是一般廣泛常被使用來吸收更多光子與增加電池功率轉換效率(PCEs)的不錯設計。
本實驗採用兩階段(Two-step)陽極氧化步驟來製作AAO奈米結構。首先，以PVD濺鍍方式於矽基板及玻璃基板沉積上99.999 %純度之金屬鋁薄膜，其厚度分別為0.2 µm, 1 µm, 3 µm三種。之後進行陽極氧化步驟，每一陽極氧化循環包括一陽極氧化與擴孔兩個階段。第一階段試片以0.3 M草酸溶液、40-60 V施加電壓於25 oC進行陽極氧化處理3-10分鐘；第二階段試片接著以5 wt%磷酸移除擴孔氧化鋁，擴孔時間為20-40分鐘，可獲得一氧化鋁50-60 nm之平均孔徑。經過兩次陽極氧化循環，結果發現於矽基板成長的氧化鋁層，反射率可降至25 %以下；於玻璃基板成長的氧化鋁層，反射率則可降至17 %以下。最後，以本實驗研製的氧化鋁層實際製作於市售玻璃基板非晶矽(α-Si)薄膜太陽能電池的表面進行抗反射測試，結果發現原本未加氧化鋁層之電池表面的平均反射係數約為6.5 %。然而，第一階段以0.3 M草酸為蝕刻液，施加陽極電壓為40 V，陽極氧化時間為10分鐘；第二階段以5 wt%磷酸進行氧化鋁層的移除與擴孔，擴孔時間為20分鐘，結果其平均反射係數最低可降至5.9 %。

關鍵字

氧化鋁 ； 抗反射

並列摘要

This work is mainly to study the antireflective characteristics of anodic aluminum oxide (AAO) nanostructures for solar cell application. Ideally, a solar cell should absorb all the useful photons. However, more than 30 % of the incident light is actually reflected back from the surface of solar cells. Therefore, the antireflection coatings (ARCs) films or the textural structures are widely utilized to absorb the more light and to improve the power conversion efficiencies (PCEs) of solar cells.
In this work, a two-step anodization was used to form the AAO nanostructures. First, the 99.999 % purified aluminum thin films with the thicknesses of 0.2 µm, 1 µm and 3 µm were deposited on the silicon and glass substrates by PVD sputtering method, respectively. A formation circle of AAO nanostructures was included with an anodization and a widening of AAO. The anodization process was first carried out in a 0.3 M oxalic acid solution at 25 oC under a constant applied voltage of 40-60 V for 3-10 min. Then, the AAO was etched and widened in a 5 wt% H3PO4 solution for 20-40 min. After the two circles of AAO nanostructures formation, the AAO nanostructures with an average pore size of 50-60 nm were completed and the reflectances were reduced to 25 % and 17 % for the silicon and glass substrate, respectively. Finally, the proposed AAO nanostructures were tested and formed by using a first anodization process in a 0.3 M oxalic acid solution at 25 oC under a constant applied voltage of 40 V for 10 min and a second AAO widening process in a 5 wt% H3PO4 solution for 20 min on a conventional glass based α-Si thin film solar cell with a reflectance of 6.5 % and can reduce the reflectance of solar cell to 5.9 %.

並列關鍵字

Anti-reflection ； anodic aluminium oxide

參考文獻

1. H. Masuda and K. Fukuda, ”Ordered Metal Nanohole Arrays Made by a Two-Step Replication of Honeycomb Structures of Anodic Alumina” Science 1995,268,1466.

2. H. Masuda and M.satoh, ”Fabrication of Gold Nanodot Array Using Anodic Porous Alumina as an Evaporation Mask” Jpn. J. Appl. Phys.,part 2 1996, 35, L126.

3. O. Jessensky, F. Müller, and U. Gösele, ” Self-organized formation of hexagonal pore arrays in anodic alumina,”Appl.phys. lett. 1998, 72,1173.

4. A. P. Li, F. Muller, A. Birner, K. Nielsch, and U. Gosele, ”Haxagonal pore arrays with a50-420 nm interpore distance formed by self - organization in anodic alumina,”J Appl. Phys(1998) ,84,6023.

5. A. P. Li, F. Müller, A. Birner, K. Nielsch, U. Gösele, ”Fabrication and Microstructuring of Hexagonally Ordered Two-Dimensional Nanopore Arrays in Anodic Alumina”Adv. Mater. 1999, 11, 483.