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Institute Silicon Photovoltaics

PersiST: Perowskit-Silizium Tandemsolarzellen – Perovskite-silicon tandem solar cells

In the project PersiST, we develop monolithically integrated perovskite/silicon solar cells, aiming at efficiencies above 29%. Furthermore, we aim at realizing tandem solar cells with an active area >100 cm².


A heterojunction silicon cell provides the base for the tandem cell. A very thin layer of transparent tin dioxide was deposited on this bottom cell, followed by 500 nm of perovskite as well as 200 nm of spiro-OMeTAD hole-conductor material. Thin MoO3 serves as a protective layer between this hole conductor and the transparent top electrode of ITO. Image: S. Albrecht / HZB


The sub-project at HZB focuses on developing such tandem cells on the basis of amorphous/crystalline heterojunction (SHJ) solar cells. HZB’s main tasks in the sub-project are

  • To adapt the perovskite solar cell to the tandem structure, where the maximum process temperature is limited by the silicon heterojunction cell to ~250°C
  • To optimize charge carrier transport and the electrical connection between the sub-cells
  • To optimize the silicon solar cell as bottom cell in a tandem configuration
  • To optimize the optical design of the whole system in order to maximize overall generation and to achieve current matching of the sub-cells
  • To improve the stability of the perovskite cell
  • To avoid critical materials

Project partners are

  • Fraunhofer Institut für Solare Energiesysteme (ISE)
  • Albert-Ludwigs-Universität Freiburg
  • Helmholtz-Zentrum Berlin (Institut Silizium-Photovoltaik und Nachwuchsgruppe Perowskit Tandemsolarzellen)
  • Heraeus
  • Merck KGaA
  • SolarWorld Innovations GmbH

The project is funded by the German Federal Ministry of Economic Affairs and Energy (BMWi), reference no. 0324037C.