Vibrational dynamics in lead halide hybrid perovskites investigated by Raman spectroscopy

Ibaceta-Jana J, Muydinov R, Rosado P, Mirhosseini H, Chugh M, Nazarenko O, Dirin DN, Heinrich D, Wagner MR, Kühne TD, Szyszka B, Kovalenko M, Hoffmann A (2020)

Publication Type: Journal article

Publication year: 2020

Journal

Physical Chemistry Chemical Physics Royal Society of Chemistry

Book Volume: 22

Pages Range: 5604-5614

Journal Issue: 10

DOI: 10.1039/c9cp06568g

Abstract

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support our results with the study of FAPbBr3 which expands the identification of vibrational modes to the previously unpublished low frequency region (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).

Involved external institutions

Universität Paderborn

Germany (DE) Technische Universität Berlin

Germany (DE) Eidgenössische Technische Hochschule Zürich (ETHZ) / Swiss Federal Institute of Technology in Zurich

Switzerland (CH)

How to cite

APA:

Ibaceta-Jana, J., Muydinov, R., Rosado, P., Mirhosseini, H., Chugh, M., Nazarenko, O.,... Hoffmann, A. (2020). Vibrational dynamics in lead halide hybrid perovskites investigated by Raman spectroscopy. Physical Chemistry Chemical Physics, 22(10), 5604-5614. https://doi.org/10.1039/c9cp06568g

MLA:

Ibaceta-Jana, Josefa, et al. "Vibrational dynamics in lead halide hybrid perovskites investigated by Raman spectroscopy." Physical Chemistry Chemical Physics 22.10 (2020): 5604-5614.

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