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Posted: Nov 28, 2011
High-efficiency heterojunction silicon solar cells with copper electroplating developed
(Nanowerk News) At the 21st International Photovoltaic Science and Engineering Conference, held on November 28th – December 2nd in Fukuoka, Japan, Kaneka and imec present silver-free heterojunction silicon solar cells. The results were obtained by applying copper electroplating technology, which was developed by Kaneka based on imec's existing copper electroplating technology, A conversion efficiency of more than 21% was achieved (*) in 6-inch silicon substrates with an electroplated copper contact grid on top of the transparent conductive oxide layer.
Today, silver screen printing is the technology of choice for the realization of the top grid electrode in heterojunction silicon solar cells. The difficulty of lowering resistivity and thinning the metal line in silver screen printing prevents from achieving high efficiency and low cost. In the presented silver-free approach, the screen-printed silver is replaced by electroplated copper. Formation of top grid electrode with copper-electroplating in hetero-junction silicon solar cells is the world first result. Copper-electroplating is an economical and industry-proven process. This solution not only overcomes the disadvantages of the silver screen printing, but provides advantages such as enabling higher efficiencies and reducing fabrication costs.
These results showing beyond 21% conversion efficiency in heterojunction silicon solar cells based on imec's copper electroplating know how were obtained in a bilateral collaboration between Kaneka Corporation and imec in Leuven (Belgium). Kaneka's Photovoltaics European Laboratory is located at the imec campus in Leuven (Belgium), giving access to imec's state-of-the-art PV infrastructure and enabling close interaction between imec and Kaneka researchers. The collaboration between Kaneka and imec comprises the improvement of Kaneka's thin-film solar cells and the development of next-generation heterojunction cells.
(*) Measured in imec
Imec performs world-leading research in nanoelectronics. Imec leverages its scientific knowledge with the innovative power of its global partnerships in ICT, healthcare and energy. Imec delivers industry-relevant technology solutions. In a unique high-tech environment, its international top talent is committed to providing the building blocks for a better life in a sustainable society. Imec is headquartered in Leuven, Belgium, and has offices in Belgium, the Netherlands, Taiwan, US, China, India and Japan. Its staff of about 1,900 people includes more than 500 industrial residents and guest researchers. In 2010, imec's revenue (P&L) was 285 million euro. Further information on imec can be found at www.imec.be.
Imec is a registered trademark for the activities of IMEC International (a legal entity set up under Belgian law as a "stichting van openbaar nut"), imec Belgium (IMEC vzw supported by the Flemish Government), imec the Netherlands (Stichting IMEC Nederland, part of Holst Centre which is supported by the Dutch Government), imec Taiwan (IMEC Taiwan Co.) and imec China (IMEC Microelectronics (Shangai) Co. Ltd.) and imec India (Imec India Private Limited).
Kaneka Corporation was established in 1949 as a spin-off from the Kanegafuchi Spinning Co., Ltd. It is headquartered in Osaka, Japan and employs about 7,300 people worldwide (including consolidated subsidiaries). Kaneka's activities span a broad spectrum of markets ranging from photovoltaics, plastics, EPS resins, chemicals and foodstuffs to pharmaceuticals, medical devices, electrical and electronic materials and synthetic fibers. Kaneka has subsidiaries in Belgium, the United States, Singapore, Malaysia, China, Australia and Vietnam.
Further information on Kaneka can be found at http://www.kaneka.co.jp/kaneka-e/