Researchers across Europe have developed a graphene solar cell with perovskite materials to get a record 26.3 per cent efficiency
The team with researchers at the University of Rome Tor Vergata, the Italian Institute of Technology (IIT) and its spin-off, Graphene Flagship Associate Member BeDimensional, in cooperation with ENEA, successfully combined graphene with tandem perovskite-silicon solar cells to achieve the efficiencies. Using graphene lends itself to a new manufacturing method that could reduce the production cost of large-area solar panels.
The maximum efficiency of silicon solar cells to 32 per cent, and recent perokskite cells have topped 25 per cent. However, the latter present several manufacturing challenges, although they can be ink-jet printed across large areas. Tandem cells combine the advantages of silicon with a layer of perovskite on top for higher efficiency but with more complex manufacturing: Oxford PV kits out German tandem cell production line.
Taking the efficiency even higher, the mechanically stacked two-terminal perovskite/silicon tandem solar cell design from the Graphene Flagship has the sub-cells independently fabricated and optimised. These sub-cells are then coupled by contacting the back electrode of the perovskite top cell with the texturized and metalized front contact of the silicon bottom cell. The optical losses that come from stacking the cells are reduces by engineering the hole selective layer/rear contact structure, and using a graphene-doped layer for the perovskite top cell. This device demonstrates a 26.3% efficiency (25.9% stabilized) over an active area of 1.43 cm2.
“Our new approach to manufacture graphene-enabled tandem solar cells provides a double advantage. First, it can be applied to enhance all the different types of perovskite solar cells currently available, including those processed at high temperatures,” said said Aldo di Carlo, researcher in Graphene Flagship partner University of Rome Tor Vergata.
“But more importantly, we can incorporate our graphene using the widespread ‘solution manufacturing methods’, key to further deploy our technologies industrially and deliver large-surface, graphene-enabled solar panels,” he said.
Francesco Bonaccorso, co-founder of Graphene Flagship spin-off BeDimensional, added “This innovative approach proposed in the context of the Graphene Flagship is the first step toward the development of tandem solar cells delivering an efficiency higher than the limit of single junction silicon devices. Layered materials will be pivotal in reaching this target.”.
“There are some compatibility issues that have to be tackled before the full exploitation of the perovskite-Si tandem PVs concept. This pioneering work demonstrates that the integration of GRMs inks with on-demand morphology and tuneable optoelectronic properties in a tandem structure, can lead to high-throughput industrial manufacturing. Graphene and related materials improve the performance, stability and scalability of these devices,” said Emmanuel Kymakis, Graphene Flagship Energy Generation Work Package Leader. “The stacked silicon-perovskite configuration will act as the foundation of the new Graphene Flagship Spearhead Project GRAPES, in which a pilot line fabrication of graphene-based perovskite-silicon tandem solar cells will take place, paving the way towards breaking the 30 per cent efficiency barrier and a significant decrease on the Levelized Cost of Energy.”
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