隨著非再生能源的短缺及環保議題的考量，矽基太陽能電池日益受到重視，但也由於矽材料本身有較高反射率大約為38%，整體太陽能電池的轉換效率也不高。因此，如何有效地減少光在矽材料的表面反射率，為矽基太陽能電池研究的重要課題之一。本論文主要是設計表面微米及奈米結構當作抗反射層來減少矽薄膜太陽能電池的表面反射率，藉以提升太陽能電池的轉換效率。我們模擬了半球微結構和奈米線表面化結構，經由Lighttools套裝軟體計算光在各結構中表面反射率的大小，以討論各種結構的效應。
我們一開始先對四分之一波長厚度的抗反射層做反射率探討，並在此抗反射層上做半圓柱、波浪狀、角錐、圓錐、半球等表面化結構去做反射率比較。我們可以得到半球表面化結構有最佳的抗反射效果。本論文更針對半球微結構的半球半徑、半球間距、半球排列方式，來探討其對表面反射率的影響。其中我們提出半球中夾雜小半球之抗反射層結構，表面反射率可以下降至1.86 %。我們接著研究雙向表面化抗反射層結構，可以得到在400 nm到800 nm波段下較低之平均反射率大約為2.24 %。最後，我們也模擬了奈米線結構的表面反射率，在中心波長波段可以得到極小的反射率，我們並且分析奈米線的長度和傾斜角度對表面反射率的影響，以幫助設計高效率、低成本的太陽能電池。

For the shortage of energy and the environmental issues, the development of solar cells has become an important technology. However, solar cells have low efficiency of energy conversion due to their high surface reflection on a flat Si substrate which is 38 %. To decrease the surface reflectance of the silicon solar cells, anti-reflection coatings (ARCs) are proposed on the solar cells. We use Lighttools software to investigate several kinds of ARCs to decrease the surface reflectance.
We first consider the reflectance of the single-layer ARC with quarter wavelength. It can effectively decrease about 30 % surface reflection as compared with a flat Si substrate. The half-cylinder texture and the wave texture are designed on a PMMA single-layer coating. It is found that the half-cylinder ARC and the wave ARC can usefully diminish the surface reflectance for perpendicular light.
Low reflectance can be achieved in the hemispherical microlens ARCs over an extended spectral region for omnidirectional incident light. The impact of the microlens sizes, periods, and arrangements are investigated. The lowest normal reflectance of the closely-packed triangular-lattice hemispherical microlens ARC is 4.8%. By adding smaller hemispherical microlenses, the surface reflectance of the hemispherical microlens ARC can be as low as 1.86 %. To obtain the lowest average surface reflectance, both-sided patterned surface texture ARCs are designed. Their lowest average surface reflectance is 2.24%. Finally, we simulate the reflectance of the nanowire ARCs. The influence of the wire length and the angle of inclination are discussed for high-efficiency and low-cost solar cells.

1.Introduction 1
1.1 Motivations 1
1.2 Chapter Outline 4

2.SimulationTool 11
2.1 Overview 11
2.2 Principle of the Simulation Tool 11
2.3 Simulation Setup 15

3.Numerical Results of Simple Anti-Reflection Coating 19
3.1 1-D Structure of Single Layer ARC 19
3.2 ARC Structures of Half Cylinders 20
3.3 Wave ARC 21
3.4 Pyramidal and Conical ARC Texture ARCs 22

4.Numerical Results of Hemispherical Microlens Anti-Reflection Coating 37
4.1 Hemispherical Microlens ARC 37
4.2 Effect of Microlens Arrangement 39
4.3 ARCs Formed by Hemispherical Microlens with Mixed Sizes 39
4.4 Reversed Hemispherical ARCs 40
4.5 Both-side Patterned Surface Texture 42
4.6 Nanowire ARC 43

5.Conclusions 67
Bibliography 69

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