Empa researches new solar cells

Dübendorf ZH – Researchers at the Thin Films and Photovoltaics Laboratory of the Swiss Federal Laboratories for Materials Science and Technology (Empa) are working on the development of new, effective solar cells. These tandem solar cells are to be based on perovskite instead of silicon.

Researchers at the Swiss Federal Laboratories for Materials Science and Technology(Empa) are working on the development of new solar cells based on perovskite. According to a press release, these photovoltaic elements should achieve a higher level of efficiency than conventional silicon-based cells. The research group led by Fan Fu from the Laboratory for Thin Films and Photovoltaics is developing so-called tandem solar cells in its experiments.

These combine different layers in order to achieve a higher degree of efficiency. The scientists process two perovskites that have different band gaps. This so-called band gap of a material has the property of converting photons with a certain energy into electricity. The two band gaps of the tandem solar cell can now capture photons with two different energy levels.

With this technology, an efficiency of 45 percent can be achieved with the perovskite tandem cell. By comparison, a silicon single cell achieves 33 percent. Another advantage that the Empa researchers expect from the project lies in the cost-effective production and lower material consumption of the new solar cells. "Silicon solar cells generally require high-purity silicon monocrystals that are produced at high temperatures," research manager Fan Fu is quoted as saying in the press release. "Perovskite thin films, on the other hand, can be printed, vaporized or deposited from solution, with a correspondingly low carbon footprint."

The lighter design also enables installation on lightweight flexible films instead of rigid glass panels. This means that the new solar cells can be mounted on buildings with a low load-bearing capacity or even on car roofs, according to the press release. ce/eb

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