Vibrational dynamics in lead halide hybrid perovskites investigated by Raman spectroscopy.
Journal article

Vibrational dynamics in lead halide hybrid perovskites investigated by Raman spectroscopy.

  • Ibaceta-Jaña J Technology for Thin-Film Devices, Technische Universitat Berlin, Einsteinufer 25, 10587 Berlin, Germany. ruslan.muydinov@tu-berlin.de.
  • Muydinov R Technology for Thin-Film Devices, Technische Universitat Berlin, Einsteinufer 25, 10587 Berlin, Germany. ruslan.muydinov@tu-berlin.de.
  • Rosado P Institute of Solid State Physics, Technische Universitat Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
  • Mirhosseini H Dynamics of Condensed Matter and Center for Sustainable Systems Design, Department of Chemistry, University of Paderborn, Warburger Str. 100, D-33098 Paderborn, Germany.
  • Chugh M Dynamics of Condensed Matter and Center for Sustainable Systems Design, Department of Chemistry, University of Paderborn, Warburger Str. 100, D-33098 Paderborn, Germany.
  • Nazarenko O Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland and Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
  • Dirin DN Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland and Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
  • Heinrich D Institute of Solid State Physics, Technische Universitat Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
  • Wagner MR Institute of Solid State Physics, Technische Universitat Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
  • Kühne TD Dynamics of Condensed Matter and Center for Sustainable Systems Design, Department of Chemistry, University of Paderborn, Warburger Str. 100, D-33098 Paderborn, Germany.
  • Szyszka B Technology for Thin-Film Devices, Technische Universitat Berlin, Einsteinufer 25, 10587 Berlin, Germany. ruslan.muydinov@tu-berlin.de.
  • Kovalenko MV Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland and Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
  • Hoffmann A Institute of Solid State Physics, Technische Universitat Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
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  • 2020-02-27
Published in:
  • Physical chemistry chemical physics : PCCP. - 2020
English Lead halide perovskite semiconductors providing record efficiencies of solar cells have usually mixed compositions doped in A- and X-sites to enhance the phase stability. The cubic form of formamidinium (FA) lead iodide reveals excellent opto-electronic properties but transforms at room temperature (RT) into a hexagonal structure which does not effectively absorb visible light. This metastable form and the mechanism of its stabilization by Cs+ and Br- incorporation are poorly characterized and insufficiently understood. We report here the vibrational properties of cubic FAPbI3 investigated by DFT calculations on phonon frequencies and intensities, and micro-Raman spectroscopy. The effects of Cs+ and Br- partial substitution are discussed. We support our results with the study of FAPbBr3 which expands the identification of vibrational modes to the previously unpublished low frequency region (<500 cm-1). Our results show that the incorporation of Cs+ and Br- leads to the coupling of the displacement of the A-site components and weakens the bonds between FA+ and the PbX6 octahedra. We suggest that the enhancement of α-FAPbI3 stability can be a product of the release of tensile stresses in the Pb-X bond, which is reflected in a red-shift of the low frequency region of the Raman spectrum (<200 cm-1).
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  • English
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https://sonar.ch/global/documents/238219
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