Despite tremendous progress in efficiency and stability, perovskite solar cells are still facing the challenge of upscaling. Here we present unique advantages of reactive polyiodide melts for solvent- and adduct-free reactionary fabrication of perovskite films exhibiting excellent quality over large areas. Our method employs a nanoscale layer of metallic Pb coated with stoichiometric amounts of CH3NH3I (MAI) or mixed CsI/MAI/NH2CHNH2I (FAI), subsequently exposed to iodine vapour. The instantly formed MAI3(L) or Cs(MA,FA)I3(L) polyiodide liquid converts the Pb layer into a pure perovskite film without byproducts or unreacted components at nearly room temperature. We demonstrate highly uniform and relatively large area MAPbI3 perovskite films, such as 100 cm2 on glass/fluorine-doped tin oxide (FTO) and 600 cm2 on flexible polyethylene terephthalate (PET)/indium tin oxide (ITO) substrates. As a proof-of-concept, we demonstrate solar cells with reverse scan power conversion efficiencies of 16.12% (planar MAPbI3), 17.18% (mesoscopic MAPbI3) and 16.89% (planar Cs0.05MA0.2FA0.75PbI3) in the standard FTO/c(m)-TiO2/perovskite/spiro-OMeTAD/Au architecture.

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N.A.B., A.A.P., A.Yu.G., S.A.F., E.A.G. and A.B.T. acknowledge financial support from the Ministry of Education and Science of the Russian Federation, Project Number: RFMEFI60716X0147 and JSC “Krasnoyarskaya HPP”. I.T, S. Kazaoui, S.A. and T.U. acknowledge the support of the New Energy Development Organization of Japan. I.T. and S. Kazaoui thank Hiroshi Tomiyasu, Eisuke Ito (CEREBA) and Tetsuo Tsutsui (Kyushu University) for assistance. I.T. expresses gratitude to Anna Pavlova for her support.

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Author notes

  1. These authors contributed equally: Ivan Turkevych, Said Kazaoui.


  1. Chemical Materials Evaluation and Research Base (CEREBA), Tsukuba, Japan

    • Ivan Turkevych
    • , Toshiyuki Urano
    •  & Shinji Aramaki
  2. Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo, Japan

    • Ivan Turkevych
  3. National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan

    • Said Kazaoui
    •  & Michio Kondo
  4. Laboratory of New Materials for Solar Energetics, Department of Materials Science, Lomonosov Moscow State University (MSU), Moscow, Russia

    • Nikolai A. Belich
    • , Aleksei Y. Grishko
    • , Sergey A. Fateev
    • , Andrey A. Petrov
    • , Eugene A. Goodilin
    •  & Alexey B. Tarasov
  5. Okinawa Institute of Science and Technology (OIST), Okinawa, Japan

    • Sonya Kosar
  6. Laboratory of Inorganic Materials, Department of Chemistry, Lomonosov Moscow State University (MSU), Moscow, Russia

    • Eugene A. Goodilin
    •  & Alexey B. Tarasov
  7. Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland

    • Michael Graetzel


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I.T. conceived the idea of the present work in discussion with A.B.T. Fabrication and characterization of perovskite solar cells and films by the RP-MAGIC method were conducted by I.T., S. Kazaoui and A.B.T. The Pb/MAI interface modification method was developed by S. Kosar through overlapped evaporation. S.A. and T.U. contributed to experiment preparation. N.A.B. and A.Yu.G. developed the spray-assisted RP-MAGIC method. S.A.F. and A.A.P. measured the melting temperatures of polyiodides. E.A.G. measured Raman spectra. I.T., S. Kazaoui, A.B.T., E.A.G., M.K. and M.G. performed scientific evaluation of the data. The manuscript was written by I.T., E.A.G., S. Kazaoui, S. Kosar, A.B.T. and M.G. The project was planned, directed and supervised by I.T. and A.B.T. All the authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Alexey B. Tarasov.

Supplementary information

  1. Supporting information

    Supplementary text and Supplementary Figs. 1–16

  2. Reporting Summary

  3. Supplementary Video 1

    Fabrication of large area MAPbI3 film on flexible PET/ITO substrate

  4. Supplementary Video 2

    Conversion of the Pb/MAI bilayer into MAPbI3 with a crystallite of iodine as iodine source

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