27.1% Perovskite/Si Tandem Cell from IMEC

• Imec says its4-terminal perovskite/silicon tandem PV cell has achieved power conversion efficiency of 27.1%
• It used a 0.13 cm² spin-coated perovskite cell and stacked it on top of a 4 cm² industrial interdigitated back-contact (IBC) silicon cell in a 4-terminal configuration for its research
• Careful engineering of perovskite material can lead to power conversion efficiency of over 30%, claims Imec
• The research team opines that adding perovskite on top of industrial silicon PV may just be the most cost-effective approach to further improve the efficiency of photovoltaics

Belgium based research and innovation hub in nanoelectronics, energy and digital technology, Imec has announced a power conversion efficiency of 27.1% for its 4-terminal perovskite/silicon tandem PV cell. It achieved the feat in partnership with EnergyVille, which is a collaboration of Flemish research centres KU Leuven, VITO, Imec and UHasselt.

Imec is confident that further careful engineering of the perovskite material can bring efficiencies of over 30%. It now invites companies in the PV value chain to partner for further research.

For their experiment, Imec used a 0.13 cm² spin-coated perovskite cell and stacked it on top of a 4 cm² industrial interdigitated back-contact (IBC) silicon cell in a 4-terminal configuration. The tandem device was then scaled up using a 4 cm2 perovskite module on a 4 cm2 IBC silicon cell to achieve tandem efficiency of 25.3%, surpassing the stand-alone efficiency of the silicon cell.

Perovskite solar cells and modules with their ability to turn semi-transparent can be used atop silicon solar cells. Engineered carefully, it can help minimize thermal loss that occurs in the silicon cell. This is why, Imec believes that perovskite-silicon tandem cell can reach over 30% power conversion efficiency.

"We have been working on this tandem technology for two years now, and the biggest difference with previous versions is in the engineering and processing of the Perovskite absorber, tuning its bandgap to optimize the efficiency for tandem configuration with silicon," said Doctoral Researcher at Imec/Energyville, Manoj Jaysankar.

Group Leader for thin-film photovoltaics at Imec/Energyville, Tom Aernouts believes adding perovskite on top of industrial silicon PV may prove to be the most cost-effective approach to further improve the efficiency of photovoltaics.

Recently, EPFL and CSEM scientists recently achieved a 25.2% record efficiency for tandem solar cell based on silicon and perovskite (see 25.2% Record For Si-Perovskite Cell).

However, despite very fast efficiency improvements for perovskite solar cells in recent years, there are still many challenges to overcome, in particular the limited lifetime, before this technology will be able to be commercialized on a large scale.