Tandem Solar Cells: Paving the Way for Industrial Production
Perovskites are regarded as promising materials for solar cells. They are particularly suitable for tandem solar cells that combine a cell made of silicon and one of perovskite. With two new, highly innovative production facilities, researchers are now creating the basis for future production on an industrial scale.
Solar cells made of perovskite materials have undergone unprecedented development. Just a few years ago, they could only achieve meagre energy yields with efficiencies of around 10 %. Today, the latest cells impressively provide more than twice this efficiency. Research groups at the Helmholtz Zentrum Berlin for Materials and Energy (HZB) have been instrumental in this rapid and considerable improvement in cell characteristics. For example, a group headed by Prof. Steve Albrecht holds the current world efficiency record of 29.1 % for tandem solar cells made of perovskite and silicon.
In tandem for higher energy yield
This novel type of tandem solar cell consists of a silicon cell and a second, superposed cell based on a semiconductor compound with a perovskite structure. The advantage of combining different materials is that their absorption spectra complement each other. The wavelengths of sunlight that silicon makes poor use of can be converted into significantly more electrical energy using suitable and inexpensive to produce perovskite compounds. Tandem solar cells can thus considerably exceed the physical efficiency limit of 29.4 % that silicon solar cells exhibit today.
“Our goal is to increase the efficiency of these novel cells to more than 30 %, not only at a laboratory scale, but also when produced on a commercial scale,“ says Prof. Bernd Stannowski, who is heading the work on this at the Competence Centre Photovoltaics Berlin of the HZB. “Together with Steve Albrecht's team, we are focusing on new modular systems that will raise the fabrication scale of silicon-perovskite tandem solar cells to a level appropriate for industry,” says Stannowski. “This will make it possible to produce tandem cells on 6-inch wafers, as commonly used in the photovoltaic industry”. For this purpose, HZB researchers now have a cluster facility from the Swiss company Indeotec at their disposal, as well as a new vacuum deposition system for various materials to conduct research into hybrid silicon-perovskite structures starting in 2021.