Solliance, the European thin film solar PV research organization, along with US based MiaSole Hi-Tech Corp have announced reaching a power conversion efficiency of 26.5% for a tandem solar cell, using a rigid semi-transparent perovskite solar cell on top and a flexible copper indium gallium selenide (CIGS) cell on the bottom.
According to the team, they were able to achieve this efficiency by optimizing the bandgap and the efficiency of both the cells.
They shared that the CIGS cell was roll-to-roll produced on steel foil with a power conversion efficiency of 20%. The team developed a stable and scalable semi-transparent perovskite solar cell on glass for their research and transferred it to a flexible carrier enabling a fully flexible, highly efficient solar foil.
To improve efficiency, the team optimized the device to maximize visible light conversion along with infrared light transparency to allow the majority of infrared light to reach the bottom CIGS cell, leading to an efficiency of 17.5% for the top device 'measured at the maximum powerpoint, tracked for 5 minutes.
"Rollable, ultra light, solar cells and modules have dramatically expanded the applications of solar energy in infrastructure, electrical vehicles, and mobile energy markets," said MiaSole CEO Dr. Jie Zhang. "MiaSolé has delivered a rollable solar cell efficiency of 20.56% and a large area module efficiency of 18.64% on production ready equipment, and we will keep breaking more world records together with Solliance to build perovskite/CIGS tandem technology for the future."
A partnership of companies, R&D institutes and universities from the Netherlands, Belgium and Germany, Solliance says it was supported by imec, TNO and Eindhoven University of Technology (TU/e) for this research work.
Back in 2019, both Solliance and MiaSole reported 21.5% efficiency for the same configuration, except that the perovskite used was a flexible semi-transparent cell (see 21.5% Efficiency For Flexible Tandem Cell).