Imec has announced a new 24.6% efficiency for a tandem CIGS solar cell based on perovskite. The institute said that its perovskite cell, developed in partnership with Dutch BIPV consortium, Solliance and EnergyVille, a joint venture between the Flemish research partners KU Leuven, VITO, UHasselt and Imec, has been combined with a CIGS cell, developed by Germany’s Centre for Solar Energy and Hydrogen Research (ZSW).
The new device uses light in the visible part of the solar spectrum, while the light in the near-IR spectrum that passes through the perovskite cell is harvested by the underlying CIGS cell, Imec explained, thus enabling the 4-terminal tandem cell significantly to outperform the stand-alone perovskite and CIGS cells.
Imec explained that the record efficiency was achieved thanks to two innovations it applied: the improvement of the transmittance of the perovskite cell for near-IR light through the addition of optical coupling layers to the tandem stack and the optimization of the transparent electrodes; and the optimization of the wide bandgap of 1.72eV.
“The CIGS cell of 0.5cm² size has been made at the high-efficiency line at ZSW, employing all optimized processes necessary for the preparation of record devices,” the research institute said in its statement.
In July, Imec announced a 27.1% efficiency on its perovskite/silicon tandem cell.
The company’s latest efficiency records are approaching that of U.K./Germany-based perovskite specialist, Oxford PV, which has hit 27.3% efficiency on a 1cm² tandem cell.