Joint project: 27plus6 – Evaluation of innovative photovoltaic materials and individual processes at flagship efficiency level

Dr. Michael Rienäcker
Tel.: +49(0)5151-999 634

Subproject: Evaluation platform for silicon single-junction solar cells and silicon-perovskite tandem solar cells based on POLO IBC solar cells and gas phase-based perovskites

The project ’27plus6′ has the ambitious technological goal of achieving flagship efficiencies at record levels for crystalline silicon (c-Si) solar cells and for c-Si/perovskite tandem solar cells. The project shall help the participating partners to evaluate, further develop and simplify innovative single processes and new materials by cross-processing and to promote them on the basis of the achieved flagship results. This will strengthen the position of the industrial partners in international competition. A technological unique selling point of this project is the development of Si/Perovskite tandem solar cells in the so-called 3-terminal architecture, which combines the advantages of the more common 2-terminal and 4-terminal tandem solar cells. The used monolithic design of the tandem solar cells requires only few contact layers and minimizes the parasitic absorption losses. At the same time, there is no need for current matching between top and bottom cell. Compared to 2-terminal solar cells, this results in an increased flexibility regarding the band gap and thickness of the perovskite absorber in the top cell as well as reduced optical losses compared to 4-terminal solar cells, and thus an increased yield under realistic irradiation conditions (during the course of the day or year).


Karlsruher Institut für Technologie (KIT), centrotherm international AG

Duration of the project

01.04.2020 – 31.12.2023


The project is funded by the Federal Ministry for Economic Affairs and Climate Action under grant no 03EE1056A. The responsibility for the content of this publication lies with the authors.

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