imec and Kaneka have introduced zero-silver, silicon-based hetero-junction solar cells at the 21st International Photovoltaic Science and Engineering Conference being conducted from 28 November to 2 December 2011 in Fukuoka, Japan.
The hetero-junction silicon solar cells were fabricated using a copper electroplating technology designed by Kaneka on the basis of the current copper electroplating technology of imec. The solar cells comprising 6" silicon substrates and an electroplated copper contact grid over the transparent conductive oxide layer have achieved over 21% conversion efficiency. The high conversion efficiency is a result of a bilateral partnership between imec and Kaneka.
The Photovoltaics European Laboratory of Kaneka situated at the imec campus located in Leuven, Belgium allows researchers of the two companies to closely interact and offers access to the advanced photovoltaic infrastructure of imec. The partnership between imec and Kaneka includes the development of future-generation hetero-junction solar cells and enhancement of thin-film solar cells of Kaneka.
So far, silver screen printing technology has been considered as the ideal method for fabricating the top grid electrode in silicon-based hetero-junction solar cells. However, the difficulty of minimizing resistivity and making thinner metal lines are the major drawbacks of the silver screen printing technology, causing high cost and low efficiency.
imec and Kaneka’s zero-silver method replaces the screen-printed silver with electroplated copper. It is the first time that a top grid electrode is created using copper-electroplating technology in silicon-based hetero-junction solar cells. Copper electroplating is a low-cost process that eliminates the drawbacks of the silver screen printing, while providing benefits such as low production costs and higher efficiencies.
Source: http://www2.imec.be