Kaneka and imec report a large-area (6-in, semi-square)
heterojunction silicon solar cell with a certified power conversion efficiency
of 22.68% with an electroplated copper contact grid on top of the transparent
conductive oxide layer. This breakthrough is achieved at Kaneka Osaka laboratory
using Kaneka’s copper electroplating technology which is based on imec’s 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 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.

Kenji Yamamoto, general manager of Kaneka’s Photovoltaics
European Laboratory says that “Kaneka is proud to have achieved this result
which was made possible through the initial developments made by imec.”

Jef Poortmans, director PV technologies at imec: “We are
excited that we could support Kaneka in developing this breakthrough results.
They prove the capabilities of copper metallization for next-generation solar cells
and strengthen our belief that in the future copper will play an important role
in high efficiency and sustainable solar cell technology.”

Source: Imec