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標題: Hydrogenated amorphous silicon solar cells with graded energy-gap
作者: 翁暄美
Weng, Hsuan-Mei
關鍵字: 太陽電池;solar cell;氫化非晶矽薄膜;漸進式能隙;amorphous;graded energy-gap
出版社: 光電工程研究所
引用: [1] William Shockley, Hans J. Queisser, Detailed Balance limit of Efficiency of p-n Junction Solar Cells, J. Appl. Phys. 32 (3) (1961) 510-519. [2] Tom Tiedje, Eli Yablonovitch, George D. Cody, B. G Brooks, Limiting efficiency of silicon solar cells, IEEE Trans. Electron. Dev. ED-31 (5) (1984) 711-716. [3] Martin A. Green, Limits on the open-circuit voltage and efficiency of silicon solar cells imposed by intrinsic auger processes, IEEE Trans. Electron. Dev. ED-31 (5) (1984) 671-678. [4] Che Mun Chong, Martin A. Green, Limiting efficiency of silicon solar cells under highly concentrated sunlight, IEEE Trans. Electron. Dev. ED-34 (11) (1987) 2351-2352. [5] 江雨龍, “第四章 矽薄膜太陽能電池,” 太陽能電池技術手冊,出版:台灣電子材料與元件協會, June 2008. [6] Tawada, Y. et al., Appl. Phys. Lett., 39, 237(1981a). [7] Tawada, Y. et al., J. de Physique, C-4. Suppl. 10, 471 (1981b). [8] Arya, R. R. et al., Appl. Phys. Lett., 49, 1089(1986). [9] Miyachi, k. et al., 11thE. C. photovoltaic Solar Energy Conference 1992. [10] Car;son D. E. et al., Photodetector having enhanced back reflection, U.S. Patent No.4,442,310;April 10,1984. [11] S.E.-D. Habib, Nadia H. Rafat, Novel band gap grading technique for enhancing the limit efficiency of solar cells, J. of Renewable Energy, Vol. 10, 2-3 (Feb./March), pp. 129-134, 1997. [12] Arturo Morales-Acevedo, Solar Energy 83, 1466 (2009). [13] B.E. Pieters et al., Thin Solid Films 451-452, 294 (2004).
為了減少矽薄膜p-i-n太陽電池在本質吸收層內部載子復合造成的損失,在氫稀釋比(R = H2/SiH4)為R = 4的條件下,使用13.56 MHz電漿增強化學氣相沉積系統,分別沉積具有均勻能隙本質、不同子層數之漸進式能隙氫化非晶矽本質薄膜及相關的太陽電池。探討薄膜能隙呈線性變化之氫化非晶矽本質薄膜對太陽電池特性的影響。
利用脈波調變射頻功率系統,變化沉積之脈波頻率1 Hz至10kHz。實驗顯示,調變脈波頻率可有效控制光學能隙的改變。
藉由控制製程條件脈波頻率,固定最大光學能隙和最小光學能隙差為0.0182 eV及厚度為300 nm,改變不同子層數分別為5 ~ 60子層;製作漸進式光學能隙薄膜並做為太陽電池吸收層。
太陽電池特性分析結果顯示,漸進式光學能隙薄膜太陽電池之開路電壓皆大於等於均勻能隙太陽電池之開路電壓。漸進式光學能隙薄膜太陽電池隨著吸收子層數由5層增加到60層,填充因子由66.43%下降至 64.75%。短路電流密度也從12.56 mA/cm2降低至11.80 mA/cm2。轉換效率也由6.86%降低至6.21%。
漸進式光學能隙薄膜太陽電池轉換效率之光照衰退率約為13% ~ 16%,略高於均勻能隙轉換效率的光照衰退率(~ 13%)。兩種太陽電池經自然太陽光照射六天後,轉換效率高低次序和初始轉換效率之高低次序一致;即初始轉換效率比均勻能隙薄膜結構太陽電池好的漸進式光學能隙結構薄膜太陽電池,經光照衰退後,仍高於均勻能隙結構太陽電池的轉換效率。

In order to reduce the photo-generated carriers recombination loss in the intrinsic absorption layer of the silicon thin-film p-i-n solar cells. In this study, the influence of linearly graded band-gap structure of hydrogenated amorphous silicon (a-Si:H) intrinsic layer, to increase the electric filed, on the performance of solar cells are investigated in detail. The graded band-gap structure of a-Si:H thin film solar cell, which consists of numerous homogeneous sublayers with varying energy-gap are fabricated using plasma-enhanced chemical vapor deposition (PECVD) with pulse-wave modulation RF power by varying the pulse frequency in the range from 1 Hz to 10 kHz, and under the condition of hydrogen to siliane ratio (H2/SiH4) equal to 4, the total i-layer film thickness is 300 nm. The optical-gap difference between the maximum and minimum values of a-Si:H films fabricated by different pulse frequencies is about 0.0182 eV, the number of sublayers is changed from 5 layers to 60 layers, respectively.
The optical band gap of a-Si:H film can be well controlled by varying the pulse frequency. The solar cells with graded band-gap i-layer structure, in contrast to the cells with uniform band-gap structure, exhibit large open circuit voltage and high energy conversion efficiency. While the number of sublayers increase from 5 layers to 60 layers, the filled factor, the short-circuit current and the conversion efficiency decrease from 66.34% to 64.75%, 12.56 mA/cm2 to 11.80 mA/cm2 and 6.86% to 6.21%, respectively.
After 6 days of direct nature sunlight illumination, the conversion efficiency of solar cells with graded energy-gap intrinsic structure decreased about 13% ~ 16%, slightly larger than the (~ 13%) of uniform band-gap solar cells. In addition, the order of conversion efficiency between each sample is the same as before photo degradation. The solar cells with graded energy-gap intrinsic structure still have higher conversion efficiency (> 5.6%) than those solar cells with uniform energy-gap intrinsic structure after 6-days direct nature sunlight illumination.
其他識別: U0005-2708201023444400
Appears in Collections:光電工程研究所

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