Regensburg 2022 – wissenschaftliches Programm
KFM 20.6: Vortrag
Mittwoch, 7. September 2022, 16:15–16:30, H34
Dissecting Ultrafast Polarization Responses in Lead Halide Perovskites via the THz-induced Kerr Effect — •Maximilian Frenzel1, Marie Cherasse1,2, Joanna Urban1, Feifan Wang3, Bo Xiang3, Leona Nest1, Lucas Huber3, Martin Wolf1, X.-Y. Zhu3, and Sebastian F. Maehrlein1 — 1Fritz Haber Institute of the Max Planck Society, Department of Physical Chemistry, Berlin, Germany — 2LSI, CEA/DRF/IRAMIS, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, France — 3Columbia University, Department of Chemistry, New York City, USA
The microscopic origin of the surprising optoelectronic properties of lead halide perovskite (LHP) semiconductors is still under debate. One hypothesis is that the highly polar and anharmonic lattice of LHPs influences their optoelectronic properties through dynamic charge carrier screening. We therefore study the ultrafast polarization response of the hybrid LHP MAPbBr3 when exposed to transient electric fields in the form of intense, single-cycle THz pulses. By probing the THz-induced Kerr effect (TKE), we observe strong THz polarizability and complex ultrafast polarization dynamics. We perform 4-wave-mixing simulations, which show that it is crucial to account for anisotropic and dispersive light propagation for the correct interpretation of the measured TKE signals. Finally, we unveil a coherent phonon response in MAPbBr3, which we assign to the inorganic cage and conclude to be the dominating polarizable mode in this material. This finding highlights the role of the inorganic lattice for dynamic carrier screening and the related mechanism of charge carrier protection.