水熱法合成氧化鋅奈米柱陣列於三五族多接面太陽能電池抗反射層之研究
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Date
2014
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本論文探討在結合多層膜與折射率漸變結構的概念下，將氧化鋅奈米柱以水熱法成長於二氧化鈦薄膜上，並理論計算出最佳之折射率匹配組合，用於提升磷化銦鎵/砷化鎵/鍺三接面串接式太陽能電池之光電功率轉換效率。本研究先透過橢圓儀分析，將氧化鋅奈米柱等效分成三層複數折射率之物理薄膜，再代入艾里方程式(Airy formula) 計算其整體光學反射率。實驗上，我們所提出之氧化鋅奈米柱/二氧化鈦複合式多層抗反射結構展現出極低的反射率(average reflectivity, Ravg~5.7%)，並具有全波段與對角度不敏感的特性，此與理論計算數值十分吻合。
我們更進一步地與傳統的雙層抗反射膜二氧化矽/二氧化鈦以及單純氧化鋅奈米柱作比較，發現在垂直入射的條件下，氧化鋅奈米柱/二氧化鈦抗複合式多層抗反射結構能使多接面太陽能電池其電流密度提升約31.3%，而二氧化矽/二氧化鈦及氧化鋅奈米柱僅分別有27.3% 與28.7%的提升。當太陽光入射角度增加至80度時，氧化鋅奈米柱/二氧化鈦複合式多層抗反射結構依然能在元件電流密度提升約35.2%；反之，氧化鋅奈米柱卻只有24.3%的提升，而二氧化矽/二氧化鈦抗反射層的提升更降低至9.4%。
因此，本論文所提出的結構，對於太陽能電池光電功率轉換效率的提升有極大的效益，且因對太陽光之入射角度不敏感，能提供較佳的封裝容忍度于後續的電池模組整合。此外，本論文結構製作容易且成本低廉，預期將能廣泛地應用於其他不同材料系統之太陽能電池結構。
In this study, we theoretically and experimentally demonstrate a novel antireflection coating (ARC) structure by hydrothermally growing ZnO nanorods (NRs) upon titanium dioxide (TiO2) layer to enhance the overall power-conversion efficiency of InGaP/GaAs/Ge triple junctions solar cells. It was shown that our proposed ZnO NRs/TiO2 hybrid structure exhibits excellent broadband and omnidirectional AR behaviors, and remarkably enhances the omnidirectional photovoltaic performance of solar devices. As compared to other conventional ARC structures, the proposed ZnO NRs/TiO2 hybrid ARC improves the short-circuit current (JSC) of the solar device to about 31.3% under the normal incidence of solar illumination, and those are enhanced to about 27.3% and 28.7% by employing the conventional SiO2/ TiO2 double layers and pure ZnO NRs ARCs, respectively. Significantly, such JSC enhancement of ZnO NRs/TiO2 hybrid ARC remains in still even the incident angle of solar light increases to 80°, whereas that reduces to only 24.3% and 9.4% for the conventional SiO2/ TiO2 double layers and pure ZnO NRs ARCs, respectively. Additionally, as the measured low-reflectivity on our ZnO NRs/TiO2 hybrid ARC is broadband and omnidirectional, it provides a great potential and tolerance for the subsequence package with photovoltaic modules, and could be directly applied to other kinds of solar cells with different composited materials.
In this study, we theoretically and experimentally demonstrate a novel antireflection coating (ARC) structure by hydrothermally growing ZnO nanorods (NRs) upon titanium dioxide (TiO2) layer to enhance the overall power-conversion efficiency of InGaP/GaAs/Ge triple junctions solar cells. It was shown that our proposed ZnO NRs/TiO2 hybrid structure exhibits excellent broadband and omnidirectional AR behaviors, and remarkably enhances the omnidirectional photovoltaic performance of solar devices. As compared to other conventional ARC structures, the proposed ZnO NRs/TiO2 hybrid ARC improves the short-circuit current (JSC) of the solar device to about 31.3% under the normal incidence of solar illumination, and those are enhanced to about 27.3% and 28.7% by employing the conventional SiO2/ TiO2 double layers and pure ZnO NRs ARCs, respectively. Significantly, such JSC enhancement of ZnO NRs/TiO2 hybrid ARC remains in still even the incident angle of solar light increases to 80°, whereas that reduces to only 24.3% and 9.4% for the conventional SiO2/ TiO2 double layers and pure ZnO NRs ARCs, respectively. Additionally, as the measured low-reflectivity on our ZnO NRs/TiO2 hybrid ARC is broadband and omnidirectional, it provides a great potential and tolerance for the subsequence package with photovoltaic modules, and could be directly applied to other kinds of solar cells with different composited materials.
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Keywords
氧化鋅奈米柱, 抗反射層, 三接面串接式太陽能電池, ZnO nanorods, Antireflection coating, triple junctions solar cells