利用單層聚苯乙烯奈米球於矽基太陽能電池抗反射層之研究

Abstract

目前太陽能電池在太陽光入射電池的表面時，會造成約40%以上光反射，其主要反射原因是因外部電極的大小會阻擋光的行進路徑，另外抗反射層的尺寸大小或材料的匹配也是影響光反射的原因之一。然而在1967年學者Bernhard利用電子顯微鏡在蛾眼的角膜表面發現約有200nm大小的週期性凸起的結構，此一結構會直接改變光進入空氣與角膜間的反射係數，可增加光的穿透性並降低其反射率。因此本論文研究將藉由蛾眼效應（Moth eye effect）的方式來製作矽基抗反射結構層。 此實驗是將聚苯乙烯奈米顆粒球直接鋪設於矽基板上，透過反應式離子蝕刻機（Reactive Ion Etching）做乾式蝕刻，並利用氧氣氣體蝕刻控制奈米顆粒球的尺寸大小，再利用四氟化碳氣體蝕刻控制矽基板之深度後，以製作出矽基抗反射層結構。製作完成之矽基抗反射層結構經由光譜儀量測其反射率，量測波長範圍為400nm至800nm。由反射光譜可得知，不含抗反射層結構之平面矽基板光反射量約為40%；製作抗反射層結構後，其光反射量最多可降低至8.8%，如此可達到抗反射的效果。以此方法製作之抗反射層結構具有較低成本、製作簡易、設備要求低的優點，並冀望可應用於矽晶太陽能電池上，並改善矽基抗反射層結構及改善太陽能電池整體之效率。

Recently, the solar cell will cause more than 40% reflection of light. The main reason for reflection is due to the size of the external electrodes. The other reason is the size of anti-reflection layer and material match. In 1967, Bernhard found out that there are about 200nm periodic uplift structure on the corneal surface of moth eyes. This structure will directly change the reflection coefficient between the corneal and the air. Besides, the penetration of light will increase and the reflectivity will decrease. This study will produce Silicon-based anti-reflection structure layer by using Moth eye effect. The procedure of the experiment are laying single layer of the polystyrene nano-particles on the Silicon-based substrate. Second, the size of nano-particles are controlled by dry etching using oxygen and the depth of silicon substrate is controlled by dry etching using CF4. Those dry etching are using “Reactive Ion Etching”. After the procedure, we could get the Silicon-based anti-reflection layer structure. We measured the reflection spectrum of the Silicon-based anti-reflection layer structure. The range of wavelength is 400nm to 800nm. The reflectivity of light compare to the sample with and without anti-reflection layer is about 40% and 8.8%. The result of reflection spectrum shows that the anti-reflection layer could increase the effect of anti-reflection. The advantages of this method are cost down, simple production, lower requirement of experiment device. It could used in the crystal silicon solar cells to improve the anti-reflection layer structure and increase the efficiency of the solar cells.