成果報告書詳細
管理番号20110000000427
タイトル*平成22年度中間年報 新エネルギー技術研究開発/革新的太陽光発電技術研究開発(革新型太陽電池国際研究拠点整備事業)/低倍率集光型薄膜フルスペクトル太陽電池の研究開発(放熱基板カルコパイライト系集光型セル)
公開日2011/7/28
報告書年度2010 - 2010
委託先名青山学院大学
プロジェクト番号P07015
部署名新エネルギー部
和文要約和文要約等以下本編抜粋:1. 研究開発の内容及び成果等 本研究拠点の目標は、集光による高効率化を前提としており、集光時におけるセルの温度上昇の抑制を考慮した集光型セルの開発はテーマ全体にとっても重要である。そこで、本研究では、この対策として、放熱を考慮したミドルおよびナローギャップ・カルコパイライト系集光型セルを開発し、低倍率集光で40%を狙うための要素技術を開発する。また、開発した技術を中心機関と連携してワイドギャップセルと組み合わせた低倍率集光型薄膜フルスペクトル太陽電池に適用し、低倍率集光多接合セルを共同開発する。
英文要約Title : NEDO Innovative PV Technology. Full Spectrum Thin Film Solar Cells with Low Concentration Ratios. Chalcopyrite-Based Thin Film Concentrator Solar Cells on Metal Substrates(FY2008-FY2012)FY2010 Annual Report
1. Objectives: The objectives of this sub-project are as follows. (1) Development of deposition processes for narrow-gap Cu-In-Te-based thin-film materials. (2) Fabrication and evaluation of CuIn3Te5 thin-film solar cells. (3) Evaluation of CuIn3Te5 thin-film solar cells under low concentrated light. The target efficiencies until FY2010 are 10% (Narrow-gap, Single junction, Low-concentration) 2. Experimental results 2.1 To grow the high-quality Cu-In-Te-based thin films, deposition conditions such as chemical compositions (Cu/In and Te/(Cu+In)atomic ratios), substrate temperature, and Te deposition rate were optimized. As a result, the crystalline quality of CuIn3Te5 thin films (Cu/In=0.31, Te/(Cu+In)=1.3-1.4, Eg = 1.03 eV) grown at 250 degrees Celsius was improved with a high Te deposition rate. The preferred (112)-oriented CuIn3Te5 films with triangular grains were obtained. Undesirable phases such as low-resistive Cu2-xTe and elemental Te were not observed in the films. 2.2 A solar cell with a ZnO:Al/ZnO/CdS/CuIn3Te5/Mo/SLG structure was fabricated. A total area (0.50 cm2) efficiency of 6.9 % with Voc=0.407 V, Jsc= 33.1 mA/cm2, and FF= 0.514 was achieved. The improved photovoltaic performance is attributed to the relatively high-quality CuIn3Te5 layer with highly (112)-oriented large grains. The QE value of the cell in the wavelength range of 550-570 nm was higher than that of a standard CIGS solar cell fabricated in our laboratory. This is in good agreement with the growth of the well-developed grains near the surface of the CuIn3Te5 thin films. However, the significant QE loss in the longer wavelengths above 580 nm are presumably due to a short diffusion length of photo-generated carriers which is related to the poor crystalline quality of CuIn3Te5 thin films near the Mo/SLG substrates. In addition, there exists no graded bandgap structure in the layers. Further improvement in cell performance is possible if the electrical active defects in the cells are clarified in order to suppress the recombination both in the CuIn3Te5 and at the CdS/CuIn3Te5 interface. 2.3 The photovoltaic parameters as a function of concentration ratios were investigated for CuIn3Te5 solar cells with different total areas (0.18, 0.32, and 0.50 cm2). It was found that the best efficiency was obtained at 5 Suns for the smallest cell (0.18 cm2). The cell performances were not degraded after the concentrated illuminations.The increase in Voc was observed at higher concentrated suns. However, the values of Voc at higher suns are lower than those of the Voc calculated from ΔVoc = 58 mV * n * log. This is due to the increased cell temperatures which are related to insufficient cooling. The values of FF decreased significantly for the cells with large areas under higher concentrated suns. Therefore, improvements in both Al-grid designs and the electrical properties of ZnO:Al layers are essential to reduce serious resistance of the cells.
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