Imec and Kaneka achieve breakthrough in heterojunction solar cells

June 12, 2012 // By Jean-Pierre Joosting
Kaneka and imec report A large area (6 inch semi-square) heterojunction silicon solar cell with a certified power conversion efficiency of 22.68 percent (certified by Fraunhofer ISE CalLab) with an electroplated copper contact grid on top of the transparent conductive oxide layer has been developed by Kaneka and imec.

This breakthrough was achieved at the Kaneka Osaka lab using Kaneka’s copper electroplating technology which is based on imec’s state-of-the-art copper electroplating knowhow.

To realize the top grid electrode in heterojunction silicon solar cells, silver screen printing is the preferred technology in the PV (photovoltaic) industry. However, a drawback of this technology is the difficulty to lower resistivity and to thin the metal line in silver screen printed contacts. As a result, efficiencies remain below optimal and cost remains relatively high. Replacing the screen-printed silver with electroplated copper overcomes the disadvantages of silver screen printing, enabling higher efficiencies and reduced fabrication costs.

Kaneka’s Photovoltaics European Laboratory is located at the imec campus in Leuven (Belgium), with access to imec’s state-of-the-art PV infrastructure. The collaboration between Kaneka and imec has led to the improvement of Kaneka’s thin-film solar cells and the development of next-generation heterojunction cells. This development of large area Cu-plated heterojunction silicon solar cells is an important step towards a fab-compatible process on large area module integrated solar cells.