ZSW Boosts CIGS Solar Efficiency World Record to 22.6 Percent

The Centre for Solar Energy and Hydrogen Research BadenWürttemberg (ZSW) has boosted the efficiency world record of CIGS thin-film solar cells once again. This time, ZSW achieved 22.6 percent efficiency with their latest advance.The record-setting cell is a standard size for test cells with an area of about 0.5 cm². The Fraunhofer Institute for Solar Energy Systems ISE confirmed the results.

The achievement tops the performance of a Japanese-made cell by 0.3 percentage points. ZSW boasts that the success brings the world record back home to ZSW for the fifth time.

ZSW points out that the pace of advances in solar cell efficiency has accelerated in recent years. According to ZSW, the industry has improved the record efficiency of cells based on copper indium gallium diselenide (CIGS) more in past three years than in the previous fifteen. The increase in efficiency will eventually translate to lower cost solar power. Germany seems to be at the forefront of these efficiency improvements in CIGS thin-film solar cells. Just three months ago, the ZSW team achieved 22.0 percent efficiency, a European record.

The ZSW used the coevaporation method in a laboratory coating plant to fabricate the CIGS cell that upped this mark another 0.6 percentage points. The institute’s researchers have improved the manufacturing process at several points to get the latest performance boost. The improved manufacturing process includes the use of post-deposition treatment of the CIGS surface with alkaline metal compounds incorporated into this layer.

“I expect that we can achieve up to 25 percent efficiency in the years ahead,” says Prof. Michael Powalla, ZSW board member and Head of the Photovoltaics division. Notably, thin-film cells are also making strides in other areas. CIGS PV technology is approaching the performance of multicrystalline silicon in terms of entire-module efficiency, which is always slightly less efficient than smaller cells.