Directional Anisotropy of the Vibrational Modes in 2D-Layered Perovskites
Balaji Dhanabalan, Yu‐Chen Leng, Giulia Biffi, Miao‐Ling Lin, Ping‐Heng Tan, Ivan Infante, Liberato Manna, Milena P. Arciniegas, Roman Krahne
Abstract
samples. Temperature-dependent Raman measurements reveal that the broad phonon bands observed at room temperature consist of a series of sharp modes and that such mode splitting strongly differs for the different organic moieties and vibrational bands. Softer molecules such as BA result in lower vibrational frequencies and splitting into fewer modes, while more rigid molecules such as PEA lead to higher frequency oscillations and larger number of Raman peaks at low temperature. Interestingly, in distinct bands the number of peaks in the Raman bands is doubled for the rigid PEA compared to the soft BA linkers. Our work shows that the coupling to specific vibrational modes can be controlled by the incident light polarization and choice of the organic moiety, which could be exploited for tailoring exciton-phonon interaction, and for optical switching of the optoelectronic properties of such 2D layered materials.