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Vibrational Response of Methylammonium Lead Iodide: From Cation Dynamics to Phonon–Phonon Interactions
Author(s) -
Ivanovska Tanja,
Quarti Claudio,
Grancini Giulia,
Petrozza Annamaria,
De Angelis Filippo,
Milani Alberto,
Ruani Giampiero
Publication year - 2016
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201600932
Subject(s) - phonon , anharmonicity , orthorhombic crystal system , perovskite (structure) , raman spectroscopy , chemical physics , condensed matter physics , relaxation (psychology) , dipole , chemistry , phase (matter) , materials science , crystallography , crystal structure , physics , psychology , social psychology , organic chemistry , optics
The dynamic evolution of the vibrational interactions in the prototypical CH 3 NH 3 PbI 3 was studied through a comprehensive experimental and theoretical investigation with a focus on the interactions between the organic cations and the inorganic cage. To date, no clear picture has emerged on the critical and fundamental interactions between the two perovskite components, despite the relevance of phonons to the electronic properties of several classes of perovskites. For the first time, we have monitored the IR and nonresonant Raman response in the broad frequency range 30–3400 cm −1 and in the temperature interval 80–360 K. Strong changes in the energies of different vibrational modes with temperature are observed and examined in the framework of phonon–phonon interactions considering a significant anharmonic contribution to the phonon relaxation process. The vibrational relaxation of the bending modes and their reorientation activation energies identify that such mechanisms are governed by medium‐to‐strong hydrogen bonds in the orthorhombic phase; however, any ferroelectric ordering in the orthorhombic phase is governed mostly by dipole interactions. These changes imply that charge localization mechanisms play a primary role, and our study enriches the fundamental knowledge of phonon interactions and charge transport in CH 3 NH 3 PbI 3 for the further development of optoelectronic applications.