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: 55'-diylbis(amino-ethyl)-(22'-(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.
Acknowledgments: D.S. K.G. X.Q. V.B. M.K.J. D.B.M. S.J. and W.Y. acknowledge support from the NSF DMREF program under grant numbers DMR-1729297 DMR-1728921 and DMR-1729383. The authors acknowledge the NCSU Imaging and Kinetic Spectroscopy facility. S.M.J. thanks the Deutsche Forschungsgemeinschaft (DFG German Research Foundation) for a postdoctoral fellowship Grant No. 393196393.
Acknowledgments: D.S. K.G. X.Q. V.B. M.K.J. D.B.M. S.J. and W.Y. acknowledge support from the NSF DMREF program under grant numbers DMR-1729297 DMR-1728921 and DMR-1729383. The authors acknowledge the NCSU Imaging and Kinetic Spectroscopy facility. S.M.J. thanks the Deutsche Forschungsgemeinschaft (DFG German Research Foundation) for a postdoctoral fellowship Grant No. 393196393.