近年來，許多人嘗試將奈米或微米球作為表面織構散射體以增加薄膜太陽能電池的轉換效率，然而散射體的尺寸及折射率等參數對散射效果的影響還未被充分瞭解。在本研究中，我們使用光線追跡 (Ray Tracing) 技術的軟體，模擬將二氧化矽次微米球散佈於透明導電層(transparent conductive oxide, TCO )，探討不同的情況下的光學特性，並針對非晶矽材料的太陽能電池作最佳設計。
首先討論不同的散射體直徑對於入射光由短波長300 nm 至長波長 1200nm，從霧度及等效光程長度比來探討散射效果的優劣，了解到適用於非晶矽太陽能電池的散射體直徑是含括0.15μm至0.25μm的分佈範圍，以同時散射所需波段。並發現過厚的TCO層會將擴散光的角度侷限於TCO與非晶矽的折射角內，降低光吸收率。而後探討在不同入射光波長的主動層吸收率，換算為外部量子效率，可以計算出在標準太陽光譜下的光電流及光電轉換效率。當非晶矽材料的太陽能電池其吸收截止波長為~700nm且主動層充分吸收短波長部分(<520nm)，模擬出的結果為散射層可以讓光電流值與光電轉換效率都增加約10%。若截止波長更長，增益會更顯著。

Surface texturing with nano-/micro-meter spherical scatters has been used in recent years to improve conversion efficiency of silicon thin-film solar cells. Nevertheless the effects of different scatter parameters such as size and refractive index are not yet fully understood. In this research, we used ray-tracing technique to simulate the light scattering of a surface-textured transparent-conductive-oxide (TCO) glass using silica sub-micron spheres and studied the consequent optical properties under various situations. Then we optimized the scatter parameters for the amorphous silicon based solar cells.
We first investigated the ideal scatter sizes for efficient light scattering of wavelengths ranging from 300nm to 1200nm in terms of Haze value and absorption length ratio. The ideal scatter sizes for amorphous silicon based thin film solar cells ranged from 0.15μm to 0.25μm. And if the layer thickness of TCO is much larger than the scatter size, the diffused light angular distribution would be restricted to the refraction angle of the TCO/a-Si:H interface, leading to lower light absorption ratio. Furthermore, we calculated the light absorption ratio of the active layer for different incident wavelengths and thus obtained the external quantum efficiency, photocurrent and conversion efficiency when illuminated by standard one-sun AM1.5G solar light. Assuming the absorption edge wavelength is ~700nm and the active layer fully absorbs light of < 520nm wavelength, the addition of scatters would improve the conversion efficiency and the photocurrent by ~10%.

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