For the first time, researchers from the École polytechnique fédérale de Lausanne (EPFL) and CSEM in Switzerland have broken the efficiency record for tandem silicon-perovskite solar cells, surpassing the 30% mark. The new record pushes the technology beyond the limits of silicon by utilizing low-cost and scalable materials.
The EPFL PV-lab team in Neuchâtel (Dr. Xin Yu Chin, Deniz Türkay, Kerem Artuk, Dr. Mathieu Boccard, and colleagues from the Tandem Photovoltaics team led by Dr. Christian Wolff) led this research in collaboration with scientists at CSEM (Dr. Brett Kamino, Dr. Florent Sahli, Dr. Soo-Jin Moon, Arnaud Walter, and colleagues, led by Dr. Quentin Jeangros). It has been supported by the Swiss Federal Office of Energy, the Swiss National Science Foundation, the European Commission, the Services Industriels de Genève, and the ETH domain’s Advanced Manufacturing Initiative.
The scientific researchers used two different designs to create tandem silicon-perovskite solar cells with high efficiency creating a milestone in world history for the first time.
Silicon has long dominated the solar cell industry due to its superior efficiency, durability, low cost, and ease of manufacture. Decades of technological progress have steadily increased the efficiency of these solar cells, but with current devices approaching the material’s theoretical limit of 29.4 percent, there isn’t much room for growth.
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While perovskites are rapidly emerging as a viable alternative, this does not imply that silicon is being phased out. Instead, the two materials complement each other and absorb different wavelengths of light: silicon is good at red and infrared light, while perovskites are best at green and blue.
Accordingly, this means that tandem silicon-perovskite solar cells can achieve higher efficiencies than either material alone. The efficiency record was 25.2 percent in 2018, but it was broken twice in 2020, at 27.7 percent and 29.15 percent. Another increase in 2021 brings it to 30%.
The first used perovskite layers deposited from a liquid solution onto a smooth silicon surface and achieved an efficiency of 30.93 percent for a 1 cm2 test cell; the second used a mixed vapor and liquid solution technique to convert calcium Titanite deposited onto a textured silicon surface and achieves an efficiency of 31.25 percent for a 1-square-centimeter solar cell.
Speaking on the new development, the researchers stated that more research will be required to determine how these designs can scale to larger surfaces and their longevity.
Likewise, the Principal Investigator of the EPFL team, Christian Wolff, in his reaction said:
Tandem perovskite-on-silicon technologies have been said to have the potential to exceed the 30-per cent efficiency benchmark, but this is the first time this long-predicted potential has been demonstrated, which should hopefully pave the way for even cheaper sustainable electricity in the future. – Christian Wolff
On the other hand, Quentin Jeangros of CSEM noted that these high-efficiency results will now necessitate additional research to allow for scaling up to larger surface areas and to ensure that these new cells can maintain a stable power output on our rooftops and elsewhere over a typical lifetime.