imec beats silicon PV with 27.1% perovskite-silicon tandem cell

26 Jul 2018

Further engineering of the material will bring efficiencies over 30% in reach, say the researchers.

Imec, the research and innovation hub in nanoelectronics, energy and digital technology, within the partnership of EnergyVille, has announced a record result for its four-terminal Perovskite/silicon tandem photovoltaic cell.

With a power conversion efficiency of 27.1 percent, the latest imec tandem cell beats the most efficient standalone silicon solar cell. Further careful engineering of the Perovskite material will bring efficiencies over 30% in reach, says the imec team.

EnergyVille is a collaboration of the Flemish research centers KU Leuven, VITO, imec and UHasselt in the field of sustainable energy and intelligent energy systems, and a partner in Solliance, a partnership of R&D organizations from the Netherlands, Belgium and Germany working in thin film photovoltaic solar energy.

Spin-coated

Imec’s new record tandem cell uses a 0.13 cm² spin-coated Perovskite cell developed within the Solliance partnership stacked on top of a 4 cm² industrial interdigitated back-contact silicon cell in a four-terminal configuration.

This design is known to have a higher annual energy yield compared to a 2-terminal configuration. Additionally, scaling up the tandem device by using a 4 cm² perovskite module on a 4 cm² IBC silicon cell, a tandem efficiency of 25.3% was achieved, surpassing the stand-alone efficiency of the silicon cell.

Manoj Jaysankar, doctoral researcher at imec/EnergyVille, commented, “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.”

Tom Aernouts, group leader for thin-film photovoltaics at imec/EnergyVille, said, “Adding Perovskite on top of industrial silicon PV may prove to be the most cost-effective approach to further improve the efficiency of photovoltaics. Therefore, we invite all companies in the PV value chain that are looking into higher efficiencies, to partner with us and explore this promising path.”

About perovskite

Perovskite microcrystals are a promising material system to make high-performance thin-film solar cells. They can be processed into thin, light, semitransparent modules that can achieve a high power conversion efficiency, are inexpensive to produce, and have a high absorption efficiency for sunlight.

Because they can be made semitransparent, perovskite solar cells and modules can also be used on top of silicon solar cells. When the Perovskite is carefully engineered, the absorbance in the Perovskite minimizes the thermal losses that occur in the silicon cell. As a result, a Perovskite-silicon tandem solar cell can potentially reach power conversion efficiencies above 30 percent.