EPFL and CSEM break the 30% efficiency barrier for perovskite-silicon tandem photovoltaics and in doing so set two confirmed world records.
For the first time, tandem perovskite-silicon photovoltaic cells have exceeded the 30% yield mark, thanks to the work of scientists at the Photocells and Electronic Thin Films Laboratory (PV-Lab) of EPFL’s Faculty of Engineering and Technology (STI). in cooperation with the Swiss Innovation Center CSEM. Independently certified by the National Renewable Energy Laboratory (NREL) in the United States, these results advance the development of high-efficiency photovoltaics and pave the way for even more competitive solar power generation.
Increasing the conversion efficiency of photovoltaic cells is important for two reasons. In the long run, this is the best way to reduce the cost of solar electricity. In the short term, it is ideal for promoting the use of photovoltaics in applications where available space is limited, such as rooftops, facades, vehicles, even drones.
However, the performance of photovoltaic cells is significantly limited by their components. By far the most common technologies use silicon. Despite its success, silicon has a theoretical efficiency limit of about 29%. The level achieved by the best lab cells today is just under 27%, leaving very little room for improvement in the future.
In the race for innovation to overcome this limitation of silicon, scientists have added one or more additional cells to the silicon to create cells. tandem “. Higher-energy visible sunlight from the sun is absorbed by the top cell, while lower-energy infrared light is absorbed by the silicon cell at the rear of the tandem cell. Halide perovskites have been identified as an ideal complement to silicon because together they can more efficiently convert light into electricity without unreasonably increasing manufacturing costs. .
Double world record
” We have reached a psychological tipping point. We have experimentally confirmed the high yield potential of perovskite-silicon tandems. The 30% efficiency band was already overcome by other materials, namely III-V semiconductors used in cells with two or three junctions. However, these materials and their manufacturing processes are too expensive to facilitate the energy transition. Indeed, these devices are a thousand times more expensive than silicon photovoltaic cells. Our results are the first to show that the 30% limit can be crossed with potentially inexpensive materials and processes, which should open new perspectives for the future of photovoltaics. said Christophe Ballif, director of EPFL’s PV-Lab and CSEM’s Center for Sustainable Energy (SE-Center).
Neuchâtel researchers managed to improve the yield of two types of perovskite-silicon tandems. First, they adapted materials and manufacturing methods to deposit high-quality perovskite layers on planar silicon cells. They achieved a conversion efficiency of 30.93% per 1 cm2 cell. Second, using a new version of a hybrid deposition process that combines a vapor phase and a liquid solution compatible with silicon textural surfaces, they produced a cell with a conversion efficiency of 31.25% (still per 1 cm2).
These results constitute two new world records: one in planar architecture and one in textured architecture. The second approach provides higher current and is compatible with the structure of currently used industrial silicon photovoltaic cells. The previous conversion efficiency record for perovskite-silicon tandem photovoltaic cells was set in 2021 by a team at Helmholtz Zentrum in Berlin, which reached 29.8%.
New EPFL and CSEM records in the United States have been independently certified by the National Renewable Energy Laboratory (NREL).
A bright future
” Based on these performance results, research and development must now move forward to replicate them over larger areas and ensure that these new cells can sustain stable power generation on our roofs and elsewhere for a standard lifetime. “, says Quentin Jeangros of CSEM.” We knew that perovskite-silicon tandem technologies could potentially cross the symbolic 30% efficiency threshold. But this is the first time this long-touted hypothesis has been proven, which can hopefully pave the way for even cheaper sustainable electricity in the future. In conclusion, says Christian Wolff of EPFL.
This research work was carried out by the EPFL PV-Lab team in Neuchâtel (Dr. Xin Yu Chin, Deniz Türkay, Kerem Artuk, Dr. Mathieu Boccard and their colleagues from the EPFL “Tandem Photovoltaics” group led by Dr. Christian Wolff), in collaboration with CSEM scientists (Dr. Brett Kamino, Dr. Florent Sahli, Dr. Soo-Jin Moon, Arnaud Walter and their colleagues, under the supervision of Dr. Quentin Jeangros). They were subsidized by the Swiss Federal Office of Energy, the Swiss National Science Foundation, the European Commission, Services Industriels de Genève and the Advanced Manufacturing Initiative of the ETH domain.
© D. Türkay (EPFL), C. Wolff (EPFL), F. Sahli (CSEM), Q. Jeangros (CSEM)
Source: Engineering Sciences and Techniques | THEM
[ Article repris avec l’aimable autorisation ]
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