先端缺陷鈍化與抗電壓誘發衰退之高效能矽晶太陽能電池

High performance silicon solar cell with enhanced defect passivation and robust PID resistance

陳宗成(Tsung-Cheng Chen)

指導教授 ： 楊斯博 ； 余英松

國立交通大學/光電學院/光電系統博士學位學程/博士(2020年)

摘要

本論文目的為研究次世代高效能矽基太陽能電池，開發技術路線的擬定可以參考功率損失路徑分析資料，將現有最佳的電池片發電效率與理論發電極限相比，可以得到各功率損失路徑的功率損失量。因此，本研究致力於體缺陷優化(第三章)、表面鈍化改善(第四章)、與減輕PN結被破壞問題(第五章)。第三章旨在討論載子誘發氫鈍化技術(CIH)解決光誘發衰退(LID)問題。目前主流的硼摻雜P型太陽能電池有嚴重LID問題，其原因是照光後誘發硼氧相關的體缺陷生成。使用CIH技術中的氫鈍化效果可以鈍化這些額外生成的體缺陷，達到成品光電轉換效率非但不衰退甚至比未處理的樣品還要高。透過控制注入的氫原子數量，本研究不僅觀察到越多氫原子帶來越高效率提升，還證明了多餘的氫原子誘發另一種氫誘發衰退(HID)的問題。第四章為討論表面鈍化效果。本研究採用非傳統的原子層沉積(ALD)二氧化鈦薄膜來製作優良的P型太陽能電池表面鈍化層。此材料在我們先前研究或其他文獻均被證明可以提供優良的表面鈍化效果，但是其缺點為膜厚必須非常薄，否則此膜結構會從原本的非晶質轉為結晶質，因此失去原本的鈍化效果。本研究採用低溫鍍膜技術成功克服以上缺點，繼而成功開發出一種單層ALD二氧化鈦薄膜，其兼具優良表面鈍化效果與極佳抗入射光反射能力。另外，我們透過二次質子質譜(SIMS)分析，釐清此膜具備表面鈍化效果的機制，這也是本研究原創研究成果之一。第五章是關於太陽能模組遭受電壓誘發衰退(PID)導致PN結被破壞的系列探討。我們必須更加重視PID問題，歸因於高效能電池片使得單片模組的開路電壓提升以及未來電廠將使用1500伏特串聯電壓取代現有1000伏特串聯電壓。本團隊透過成膜品質調整、預氧化製程、與非傳統的脈衝式電漿法等三個方向的研究，成功確認我們可以減輕PID的影響直至符合國際規範(功率相對降幅小於5%)。其中，就本團隊所知，我們是第一個團隊使用脈衝式電漿法來處理PID問題。這個非傳統方法可視為新增一個實驗自由度，使得其他研究人員得以應用並處理日益嚴峻的PID問題。

關鍵字

太陽能電池 ； 矽基 ； 氫鈍化 ； 二氧化鈦 ； 電壓誘發衰退

並列摘要

In view of sustainable energy, the photovoltaic (PV) technology was thought as one of the most feasible solutions to replace fossil fuel technologies for electrical generation. However, several evidences pointed out the current PV technology can be improved either in the enhancement of power conversion efficiency or of long-term reliability concerns. In practical terms, the loss channels of PV cell were analyzed and hence the power conversion efficiency can be lifted by fixing each loss channel individually. This dissertation was dedicated in developing next-generation PV cell by minimizing the power loss through some specific channels. The addressed loss channels were in bulk (chapter 3), at front surface region (chapter 4), and at the depletion region (chapter 5). In chapter 3, the evolution of carrier-induced hydrogenation (CIH) performance was investigated by varying the refractive index of rear SiNx:H layer. The CIH technique not only avoided light-induced degradation (LID) issue, but it also enhanced power conversion efficiency of solar cell through hydrogen assistant defect passivation, i.e. hydrogenation. Most importantly, both hydrogenation and hydrogen induced degradation (HID) were found when manipulating the external hydrogen quantity. The dominance of above hydrogen behaviors would be transferred depended on the bulk quality and external hydrogen quantity. In chapter 4, the front surface passivation was addressed by a novel ALD TiO2 layer. In the past, ALD TiO2 film possessed excellent surface passivation for p-type c-Si substrate, but the drawback of limited film thickness was existed duo to film crystallization issue. Here, it was succeeded by thickening its film thickness with maintained surface passivation quality. After that, an ALD TiO2 film provided both excellent surface passivation and anti-reflection ability was demonstrated. In chapter 5, a catastrophic potential-induced degradation (PID) on PV module was discussed. Here contains three solutions for alleviating PID issue. Firstly, the films deposited by direct-type PECVD and indirect-type PECVD were compared. Next, the contribution of interface SiO2 layer between ARC layer and c-Si surface was evaluated. At last, a novel function of pulsed-plasma (PP) mode was conducted to compare the traditional continuous-plasma (CP) mode. Notably, the last-two experiments were held by indirect-type PECVD, which possessed ultra-high productivity and benefited to save manufacturing cost. As results, all of these experiments presented excellent PID-resistant ability, and they can be adopted by the module with even-higher PID concern.

並列關鍵字

solar cell ； silicon-based ； hydrogenation ； TiO2 ； potential-induced degradation

參考文獻

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