Phonon and Raman caculation data from: Coherent Phonon‐Induced Modulation of Charge Transfer in 2D Hybrid Perovskites
Electron-phonon interactions play an essential role in charge transport and transfer processes in semiconductors. For most structures, tailoring electron-phonon interactions for specific functionality remains elusive. Here, we show that, in hybrid perovskites, coherent phonon modes can be used to manipulate charge transfer. In the two-dimensional double perovskite, (AE2T)2AgBiI8 (AE2T: 5,5'-diylbis(amino-ethyl)-(2,2'-(2)thiophene)), the valence band maximum derived from the [Ag0.5Bi0.5I4]-2 framework lies in close proximity to the AE2T-derived HOMO level, thereby forming a type-II heterostructure. During transient absorption spectroscopy, pulsed excitation creates sustained coherent phonon modes, which periodically modulate the associated electronic levels. Thus, the energy offset at the organic-inorganic interface also oscillates periodically, providing a unique opportunity for modulation of interfacial charge transfer. Density-functional theory corroborates the mechanism and identifies specific phonon modes as likely drivers of the coherent charge transfer. These observations are a striking example of how electron-phonon interactions can be used to manipulate fundamentally important charge and energy transfer processes in hybrid perovskites.
