Solliance Tops 21.5% Efficiency with Flexible Perovskite-CIGS Tandem

Scientists at Solliance, in collaboration with MiaSole Hi-Tech Corp., fabricated a flexible solar cell with a record-breaking power conversion efficiency of 21.5%. The solar cell combines two thin-film solar cell technologies into a four- terminal tandem solar cell stack: a top flexible semi-transparent perovskite solar cell with a bottom flexible copper indium gallium selenide (CIGS) cell.
 
A tandem solar cell, which combines a perovskite and a Cu(In,Ga)Se2 (CIGS) cell, has the potential for high conversion efficiency exceeding single junction solar cell performance thanks to tunable and complementary bandgaps of these individual thin film solar cells.
 
CIGS technology has a proven track record as high efficiency and stable solar technology and has entered high volume manufacturing in multi-GW scale around the world. CIGS technology has been successfully used to produce high efficiency flexible and lightweight cells and modules, which address markets where heavy and rigid panels cannot be used.
 
Perovskite solar cells, despite being a relatively young technology, have already achieved high efficiencies, and promise low-cost solar technology based on abundant materials. Combining both technologies in a flexible and lightweight package expands the horizon of high performance, flexible, and customizable solar technology.
 
The perovskite solar cell was deposited on a transparent and flexible substrate, employed transparent conductive electrodes, and was optimized for maximum visible light conversion efficiency and infrared light transparency to allow the majority of infrared light to reach the bottom CIGS cell.
 
The CIGS bottom cell was developed by MiaSolé Hi-Tech, a provider of CIGS production turn-key factories and manufacturer of CIGS flexible solar panels, located in Silicon Valley, California. The CIGS cell is based on a commercially available high efficiency flexible solar cell technology fabricated on lightweight stainless-steel foil using a proprietary high throughput roll-to-cell sputtering process.
 
As result of the combined expertise of MiaSolé Hi-Tech in the area of CIGS development and manufacturing, and the expertise of the Solliance team in the area of perovskite technology, a new record efficiency flexible perovskite/CIGS tandem cell was produced. “Optimizing the bandgap of both cells was an important step in achieving this result,” said Mehrdad Najafi, researcher at Solliance Solar Research.