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High-Efficiency Multi-Junction Concepts

In our group, we investigate the use of different absorber material combinations and concepts for perovskite tandem solar cells:


Visualization of a perovskite/silicon tandem solar cell layer stack. Picture: E. Köhnen / HZB

CIGS Tandem

Cross-sectional scanning electron micrograph of a perovskite/CIGS tandem solar cell. Published under CC BY 3.0 | doi: 10.1039/C9EE02268F


Left: IBC 3T perovskite/silicon tandem solar cell in front of a mirror (left) and schematic (right). Pictures: A. Al-Ashouri (left), P. Tockhorn (right), both HZB

  • For perovskite/silicon tandem solar cells, we combine wide-bandgap perovskite layers with silicon heterojunction (SHJ) solar cells [1,2], which are developed in the group of Bernd Stannowski at PVcomB. By optimizing the fabrication process (see also Development of New Contact Materials and Tailoring Perovskite Properties), we could achieve a perovskite/silicon tandem solar cell with a certified power conversion efficiency of 29.15% [1].
  • The combination of a perovskite top cell with a CIGS (copper indium gallium selenide) bottom cell allows the fabrication of fully thin-film tandem solar cell technology with thicknesses of just a few micrometers [3,4]. In collaboration with the group of Christian Kaufmann at PVcomB, we were able to demonstrate highly efficient perovskite/CIGS tandem solar cells with world record efficiencies of 24.2% [3].
  • The widely tunable bandgap of perovskites allows not just the fabrication of the wide bandgap top cell but also the low bandgap bottom cell (see also Tailoring Perovskite Properties) in a tandem. The lower bandgap is typically achieved by alloying lead- and tin-based perovskites. Thus, all-perovskite (or perovskite/perovskite) tandem solar cells being a fascinating alternative thin-film tandem technology.
  • In addition to the typically investigated two-terminal tandem architecture, we also research other device concepts such as interdigitated back contact three-terminal (IBC 3T) tandem solar cells. Here, we experimentally demonstrated the first perovskite/silicon IBC 3T tandem solar cell with a power conversion efficiency of 17.1% [5]. The IBC 3T tandem architecture combines the %advantages of two- and four-terminal tandem architectures, omitting current-matching constraints in a monolithic device.
  • By increasing the number of absorber layers, the efficiency potential of tandem solar cells can be further increased. The tunable bandgap of perovskites in principle allows the use in triple-junction tandem solar cells. Besides the engineering of stable and efficient perovskite absorbers, in particular the optical optimization of this tandem architecture is challenging.

Key Publications:

  1. Al-Ashouri, A.; Köhnen, E.; Bor, L.; Magomedov, A.; Hempel, H.; Caprioglio, P.; Márquez, J.; Morales Vilches, A.B.; Kasparavicius, E.; Smith, J.A.; Phung, N.; Menzel, D.; Grischek, M.; Kegelmann, L.; Skroblin, D.; Gollwitzer, C.; Malinauskas, T.; Jošt, M.; Matic, G.; Rech, B.; Schlatmann, R.; Topic, M.; Korte, L.; Abate, A.; Stannowski, B.; Neher, D.; Stolterfoht, M.; Unold, T.; Getautis, V.; Albrecht, S.: Monolithic perovskite/silicon tandem solar cell with >29% efficiency by enhanced hole extraction. Science 370 (2020), p. 1300-1309
    Open Access Version (available 01.12.2021)
  2. Köhnen, E.; Jošt, M.; Morales-Vilches, A.B.; Tockhorn, P.; Al-Ashouri, A.; Macco, B.; Kegelmann, L.; Korte, L.; Rech, B.; Schlatmann, R.; Stannowski, B.; Albrecht, S.: Highly efficient monolithic perovskite silicon tandem solar cells: analyzing the influence of current mismatch on device performance. Sustainable Energy & Fuels 3 (2019), p. 1995-2005
    Open Access Version
  3. Al-Ashouri, A.; Magomedov, A.; Roß, M.; Jost, M.; Talaikis, M.; Chistiakova, G.; Bertram, T.; Márquez, J.A.; Köhnen, E.; Kasparavicius, E.; Levcenco, S.; Gil-Escrig, L.; Hages, C.; Schlatmann, R.; Rech, B.; Malinauskas, T.; Unold, T.; Kaufmann, C.A.; Korte, L.; Niaura, G.; Getautis, V.; Albrecht, S.: Conformal monolayer contacts with lossless interfaces for perovskite single junction and monolithic tandem solar cells. Energy & Environmental Science 12 (2019), p. 3356-3369
    doi: 10.1039/C9EE02268F
    Open Access Version 
  4. Jost, M.; Bertram, T.; Koushik, D.; Marquez, J.; Verheijen, M.; Heinemann, M.D.; Köhnen, E.; Al-Ashouri, A.; Braunger, S.; Lang, F.; Rech, B.; Unold, T.; Creatore, M.; Lauermann, I.; Kaufmann, C.A.; Schlatmann, R.; Albrecht, S.: 21.6%-efficient Monolithic Perovskite/Cu(In,Ga)Se2 Tandem Solar Cells with Thin Conformal Hole Transport Layers for Integration on Rough Bottom Cell Surfaces. ACS Energy Letters 4 (2019), p. 583-590
    Open Access Version
  5. Tockhorn, P.; Wagner, P.; Kegelmann, L.; Stang, J.-C.; Mews, M.; Albrecht, S.; Korte, L.: Three-Terminal Perovskite/Silicon Tandem Solar Cells with Top and Interdigitated Rear Contacts. ACS Applied Energy Materials 3 (2020), p. 1381-1392