Stacked perovskite/CIGS solar module approaches 18% efficiency

September 28, 2016 // By Graham Prophet
Researchers from imec (active in the in Solliance and EnergyVille projects), Karlsruhe Institute of Technology (KIT), and Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (Centre for Solar Energy and Hydrogen Research, ZSW), have announced that they have fabricated a thin-film solar module stack made up of perovskite and copper indium gallium selenide (CIGS) with a conversion efficiency of 17.8%.

The significant achievement is that this is the first time that a “tandem” module has exceeded the the highest efficiencies of separate perovskite and CIGS modules. The stacked module (3.76 cm ²) implements a fully scalable device concept: both the perovskite top module and the CIGS bottom module feature a monolithic interconnection scheme, using seven and four module cell stripes respectively. The result is a reduction of area loss of less than eight percent for both technologies. (In prior work, one of the limitations has been that to build a stacked scheme, more complex interconnect or power draw-off has been needed, reducing the area available for active energy collection.)


The consortium’s process for creating this efficient perovskite/CIGS multi-junction solar module relies upon efficient exploitation of the solar spectrum. The higher energy part of the spectrum is harvested in the semitransparent perovskite module on top, while the light with lower energy passes and is harvested in the bottom CIGS cell. The result outperforms the world-record upscaled perovskite module of 15.3% efficiency presented by imec, and also the highly-efficient stand-alone upscaled CIGS module of ZSW with efficiencies nearing 15.7%.


“This result was achieved through close and intricate collaboration leveraging the expertise of the three partners. Imec’s expertise in perovskite technology was underscored by the use of a perovskite top module in these stacked solar modules,” stated Dr. Tom Aernouts, head of thin-film PV research at imec.


According to Dr. Ulrich Paetzold, head of the research group at KIT, this result is just a starting point, with more exciting results to come in the next years such as perovskite/CIGS multi-junction solar modules surpassing efficiencies of 25%. The Helmholtz Young Investigator group of Dr. Paetzold is focusing on the optics in multi-junction perovskite solar modules and will develop further specialized nanophotonic materials for these devices.


Finally, ZSW contributed with its world class expertise in CIGS solar modules. ZSW holds