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Efficient bifacial monolithic perovskite/silicon tandem solar cells via bandgap engineering


Bifacial monolithic perovskite/silicon tandem solar cells exploit albedo—the diffuse reflected light from the environment—to increase their performance above that of monofacial perovskite/silicon tandems. Here we report bifacial tandems with certified power conversion efficiencies >25% under monofacial AM1.5G 1 sun illumination that reach power-generation densities as high as ~26 mW cm–2 under outdoor testing. We investigated the perovskite bandgap required to attain optimized current matching under a variety of realistic illumination and albedo conditions. We then compared the properties of these bifacial tandems exposed to different albedos and provide energy yield calculations for two locations with different environmental conditions. Finally, we present a comparison of outdoor test fields of monofacial and bifacial perovskite/silicon tandems to demonstrate the added value of tandem bifaciality for locations with albedos of practical relevance.

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Fig. 1: Perovskite/silicon bifacial tandems.
Fig. 2: Optical analysis.
Fig. 3: Outdoor testing of bifacial tandems.
Fig. 4: Analysis and energy yields of the test fields.

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All data generated or analysed during this study are included in the published article and its Supplementary Information


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This work was supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under award no. OSR-2018-CPF-3669.02, KAUST OSR-CARF URF/1/ 3079-33-01, KAUST OSR-CRG RF/1/3383, KAUST OSR-CRG2018-3737 and IED OSR-2019-4208. This work was supported in part by the US Department of the Navy, Office of Naval Research (grant award no. N00014-20-1-2572). The financial support of the German Federal Ministry for Economic Affairs and Energy (CAPITANO, funding code 03EE1038B) and the Initiating and Networking funding of the Helmholtz Association (HYIG to U.W.P. (funding code VH-NG1148), PEROSEED (funding code ZT-0024) and the Science and Technology of Nanostructures Research Program) is acknowledged. Furthermore, we are grateful for the help and support of A. Mertens and A. Rozalier from KIT in setting up the outdoor measurements in Karslruhe as well as M. Langenhorst, R. Schamger and J. Lehr for developing earlier versions of the energy-yield software. We acknowledge the support of ABET Technologies and Newport. We thank TUV Rheinland Group, Germany, for providing solar spectra from TUV’s outdoor test field on the KAUST campus, Thuwal, Saudi Arabia. We are grateful for the support of J. L. Mynar and the KAUST Corelab, and for the fruitful discussions with A. H. Balawi.

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Authors and Affiliations



M.D.B. conceived the idea; M.D.B. and A.J.M. fabricated the devices; Y.H., B.C. and A.S.S. developed the perovskite bandgaps; E.A. developed the tandem top contact and layout; E.A. and F.H.I. developed the tandem hole transport layer; M.D.B., T.G.A. and E.V.K. developed the silicon bottom cell; F.G., U.W.P. and L.X. performed the optical modelling; J.L. performed the electrical modelling; M.F.S., F.G., J.T. and J.L. developed the field-test set-up; F.G. and U.W.P. performed the energy-yield calculations; M.F.S. supervised the field-test experiment; M.D.B., M.F.S., A.S.S., F.G. and U.W.P. wrote the manuscript; D.B., B.F., E.H.S. and S.D.W. supervised the project.

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Correspondence to Edward H. Sargent or Stefaan De Wolf.

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The authors declare no competing interests.

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Peer review information Nature Energy thanks Gianluca Coletti and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1–17, Tables 1–6 and Note 1.

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De Bastiani, M., Mirabelli, A.J., Hou, Y. et al. Efficient bifacial monolithic perovskite/silicon tandem solar cells via bandgap engineering. Nat Energy 6, 167–175 (2021).

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