成果報告書詳細
管理番号20110000000833
タイトル*平成22年度中間年報 太陽エネルギー技術研究開発 太陽光発電システム次世代高性能技術の開発 極限シリコン結晶太陽電池の研究開発 (銅ペーストの研究開発)
公開日2011/6/29
報告書年度2010 - 2010
委託先名独立行政法人産業技術総合研究所
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 (1)背景 結晶Si太陽電池用電極の現状 ・主流→スクリーン印刷銀ペースト(バスライン・フィンガー電極)・めっき電極 銀ペーストの問題点 ・地金価格の高騰 → \85000/Kg(2011年1月現在) ・高温焼成(800~900℃) → ドープ層拡散による効率の低下 → ガラスフリット溶融によるpn接合破壊(シャント発生) → ヘテロ型ウエハへの適応困難(TCO劣化・剥離)
英文要約Title: High Performance PV Generation System for the Future. R and D on Ultimate Wafer-based Si Solar Cells. (Glass-fritless Cu Alloy Pastes for Low Temperature Sintering) (FY2010-FY2012)FY2010 Annual Report
Purpose of the work: This paper describes a novel Cu paste for reducing costs as well as increasing the efficiency of silicon solar cells by lowering sintering temperature and decreasing both of the line and contact resistance of electrodes. Approach: The novel Cu alloy pastes were prepared by blending Cu particles with diameter of several micrometers and homogenously mixed alloys as a low melting point solder. The pastes were screen printed on silicon substrates, followed by sintering at <200 °C. The pastes were evaluated in terms of printability, contact resistance, line resistance, adhesive property, and diffusivity of Cu in Si.
Results: Printability: The printability of a paste is reflected in the accuracy and reproducibility of the screened or stenciled paste pattern onto the land patterns. The printability was determined by the width and height of printed paste lines on textured monocrystalline silicon using the SEM images of line-patterned pastes after heating up to 150 °C for 10 min. As a result, our pastes could form well-defined lines without much spreading over the surface in the range of 60 to 170 m, compared to other commercially available pastes. Resistivity: Resistivity of a screen-printed pattern was determined by the four-point-probe method. Using our Cu-alloy paste, the resistivity of the printed pattern sintered at 150 °C for 10 min. was c.a. 7E-5 ohm*cm. This is the one of the lowest values among typical commercially-available Cu pastes except nano-particle pastes.
Contact resistance: Contact resistance between our Cu-alloy paste and lightly n-doped Si wafer was determined by the transfer length measurement (TLM) method. As a result, contact resistance of the Cu-alloy paste/the Si wafer was comparable to that of a typical Ag paste (with glass frit)/the Si wafer. Further, our paste showed excellent electrical contact to Indium Tin Oxide (ITO) electrode, therefore, our paste is sufficiently applicable to a solar cell with hetero structure. Adhesive property: Adhesive strength between a printed pattern and a wafer was estimated by the typical tape peeling test. From the result, it was estimated that the Cu-alloy paste had sufficient adhesive strength for solar-cell use. Our paste also showed very high adhesive strength to the ITO electrode surface. Conclusion: We have developed the novel Cu-alloy paste having low resistivity, low contact resistance and low sintering temperature. Various estimation results indicated that the Cu-alloy paste could be sufficiently used for solar-cell use.
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