Details

Autor(en) / Beteiligte

• Ibaceta-Jaña, Josefa
• Muydinov, Ruslan
• Rosado, Pamela
• Mirhosseini, Hossein
• Chugh, Manjusha
• Nazarenko, Olga
• Dirin, Dmitry N
• Heinrich, Dirk
• Wagner, Markus R
• Kühne, Thomas D
• Szyszka, Bernd
• Kovalenko, Maksym V
• Hoffmann, Axel

Titel

Vibrational dynamics in lead halide hybrid perovskites investigated by Raman spectroscopy

Ist Teil von

• Physical chemistry chemical physics : PCCP, 2020-03, Vol.22 (1), p.564-5614

Ort / Verlag

England: Royal Society of Chemistry

Erscheinungsjahr

2020

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• 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 FAPbI 3 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support our results with the study of FAPbBr 3 which expands the identification of vibrational modes to the previously unpublished low frequency region (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 PbX 6 octahedra. We suggest that the enhancement of α-FAPbI 3 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 ). The effect of the incorporation of Cs + and Br − in FAPbl 3 investigated by Raman spectroscopy.