表面次微米結構增加矽薄膜太陽能電池的光捕捉效率

Improvement of the light trapping in silicon thin film solar cell by surface sub-micron structure

黃建福(Chian-fu Huang)

指導教授 ： 伍茂仁 ； 張正陽

國立中央大學/理學院/光電科學研究所/碩士(2007年)

摘要

隨著矽原料的短缺及降低成本的的考量，矽薄膜太陽能電池日益受到 重視，但也由於材料厚度的減少，吸收效率隨之下降，其中更以紅外 波段影響甚大，因此如何有效的增加光在矽材料的光路徑，實為矽薄 膜太陽能電池之重要課題。本論文主要是利用表面的次微米結構提升 矽薄膜太陽能電池的光捕捉效率，提出對稱型與非對稱型次微米光柵 結構，經由FDFD 演算法觀察光在結構中各filling factor 間的耦合形 成橫向傳遞的效果。本文更針對矽材料中理論轉換效率高的近紅外波 段（900 nm~1100 nm），來分析光在矽薄膜內的停留時間，對稱型結 構與非對稱型可以將時間拉長至平面型的6 倍。在相同時間下 (C*t=25μm，C 為光速)，光在非對稱型結構矽材料內的總能量可以 增加3~3.4 倍，且角度容忍度在±40o 內總能量亦維持在3 倍。當考慮 矽材料吸收的條件下，經由優化設計的非對稱型結構可以有效的提升 矽薄膜太陽能電池等效光路徑1.3~3.3 倍，進而顯著增加矽薄膜太陽 能電池的光捕捉效率；以利於在考慮材料成本的同時亦能維持其效 率，使得矽薄膜太陽能電池更具實用性。

關鍵字

光捕捉 ； 矽薄膜太陽能電池 ； 結構

並列摘要

Silicon thin film solar cell is paid attention to think of reducing silicon materials to low cost day by day. But because of the reduction of the thickness of material, absorption will be reduce, near IR and IR especially. So, for Si thin film solar cell it is the important subject how effective increase the optical path in the silicon. This thesis is about using surface sub-micron structure to improve the light trapping of Si thin film solar cell. Two structures of symmetrical and asymmetric type each was be proposed, and performed by FDFD algorithm can observe the light coupling among the every filling factor. This thesis analyses the time of light staying in Si for near IR (900 nm~1100 nm) with high conversion efficiency to the theory in the silicon material .The symmetrical and asymmetrical structures can enhance decay time 6 times . Under the same time, total energy of light in silicon can enhance 3.4 in asymmetric structure, Under 40° of angles also maintains 3 times. As considering the absorption coefficient of materials, optimized asymmetrical structure can improve the optical path 1.3~3.3 times, and then effectively improve the light trapping. It can maintain the conversion efficiency while considering the cost of material, and make the silicon thin film solar cell have practicability even more.

並列關鍵字

light trapping ； Si thin film solar cell ； sub-micron structure

參考文獻

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