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HL: Fachverband Halbleiterphysik
HL 30: Ultrafast Phenomena II
HL 30.2: Talk
Wednesday, March 20, 2024, 10:15–10:30, EW 015
Ultrafast phonon-driven exciton Rabi oscillations in halide perovskites — X.Trung Nguyen1, Katrin Winte1, Daniel Timmer1, Yevgeny Rakita2, Sufyan Ramzam1, Caterina Cocchi1, Michael Lorke3, Frank Jahnke3, David Cahen2, Christoph Lienau1, and •Antonietta De Sio1 — 1Universität Oldenburg — 2Weizmann Institute of Science — 3Universität Bremen
Coupling electromagnetic radiation with matter is highly promising for tailoring optoelectronic properties and photoinduced dynamics of functional materials. Here we show that even the internal fields induced by coherent lattice motions can transiently control the ultrafast excitonic response in halide perovskites(HaPs). Temperature-dependent ultrafast two-dimensional electronic spectroscopy reveals that the characteristic low-frequency phonons of the soft lead-halide lattice induce strong mixing of 1s and 2p exciton manifolds in CsPbBr3 and MAPbBr3. This results in side-peaks in the spectra and 100-fs-Rabi oscillations in the dynamics. The temperature-dependence of the Rabi oscillations provides insight into dephasing mechanisms within the excited exciton manifold. Our results show that the conventional Fröhlich model is insufficient to describe the behavior of these materials. Instead, they indicate the importance of nonadiabatic couplings. An important implication is that intrinsic optical phonon fields in HaPs may be exploited to transiently modify their optoelectronic properties, and to explore fundamental field-matter interactions toward shaping coherent exciton dynamics by strong and ultrastrong coupling to phonons.