成果報告書詳細
管理番号20140000000694
タイトル*平成25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2015/2/19
報告書年度2013 - 2013
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
英文要約Title: Research and Development Projects for Solar Energy Technology. Development of Next Generation High Performance Technology for Photovoltaic Power Generation System. Research and Development of Ultimate Crystalline Silicon Solar Cells (Development of Copper Pastes) (FY2010-FY2014) FY2013 Annual Report

This report describes recent progress on Cu paste in fiscal year 2013. (1)Improvement of Cu pastes. (a)Electric contact measurements on the interface between metal electrode and silicon wafer by KFM. Electric contact measurements on the interface between metal electrode and silicon wafer were done by KFM. As a result, the interface of Si/Cu+LMPA has a relatively lower schottky barrier than Si/Ag with glass frits, which proves that the Cu has an advantage in terms of workfunction in the use of PV. (b)Plasma sintering. H2-He mixture plasma sintering was done to compare the resistivity of Cu pastes as the case of conventional heat sintering. As a result, the plasma sintering made the distance between Cu particles closer to reduce the resistivity. The reason may be due to removal of resin polymers as a binder and oxidated Cu layer on native Cu. (c)Improvement of adhesiveness of solder plated Cu ribbon on Cu electrode. Some treatments were done so as to enhance the affinity of solder to the surface of the electrode. It improves the adhesiveness 3 times compared to without any treatment.(2)Technical development for the use of conventional crystal solar cells. (a)Development of new etching process to reduce SiO2 layer.A new approach to contact glass-free metal paste onto silicon of the front side of conventional solar cells with SiNx-anti reflection coating (ARC) was developed. To open up a certain area of the ARC an etching paste containing phosphoric acid was used. The problem was a SiO2 layer generation over the opened silicon after the etching process since it is an insulator for the glass-free metal paste. Then, we found that addition of a Ag paste without glass frits into the etching paste significantly prevents the SiO2 generation, resulting in a good contact formation between the silicon and the glass-free metal paste. For example, printing a Ag resin paste on the etched area using the developed method shows a much lower specific contact resistivity compared to the case without addition of Ag paste. It is almost the same as the resistivity in the case of a conventional Ag metallization with a glass frit. Performances of solar cells with metallization using the developed method will also be discussed. (b)Utilization of Cu pastes for buss bar on PV. Cu pastes was printed and sintered as buss bars on a conventional solar cell with Ag as a finger electrode and an Al electrode as a rear electrode. Solar cell performances were evaluated using a solar simulator. As a result the Cu buss bar has almost the same conversion efficiency as the case of Ag buss bar. Amazingly, it could keep the performance even after exposure of a harsh condition such as DHT, TC test. (c)Development of screen printing technology to remove voids in printed electrode. Cu plating was chosen as one of ways to fill the voids in the electrode. Interestingly, the plating worked well to fill the inside of the electrode rather than the surface. It results in double digit decrease of the resisitivity.
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