SKM 2021 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 3: Poster Session I

HL 3.6: Poster

Montag, 27. September 2021, 10:00–13:00, P

How to Trace Structural Dynamics in Lead Halide Perovskites Using THz Kerr Effect Spectroscopy — •Maximilian Frenzel¹, Marie Cherasse^1,2, Leona Nest¹, Martin Wolf¹, and Sebastian F. Maehrlein¹ — ¹Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany — ²LSI, CEA/DRF/IRAMIS, CNRS, Ecole polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France

The origin of the surprising optoelectronic performance of lead halide perovskite (LHP) semiconductors is still debated. It has been suggested that their highly polar and anharmonic lattice might beneficially govern their optoelectronic properties in the form of dynamic charge carrier screening. To study the LHP’s ultrafast lattice polarization when subjected to a transient electric field we employ THz Kerr Effect (TKE) spectroscopy. In particular, we investigate the responses in the organic-inorganic hybrid semiconductor MAPbBr₃ and its fully inorganic counterpart CsPbBr₃. By comparing our obtained signals to four-wave mixing simulations, we find that it is crucial to account for dispersion and optical anisotropy, as certain features may be misidentified for molecular relaxation dynamics or quasi-particle oscillations. Finally, we show that strong THz fields nonlinearly excite Raman active phonons in both materials, corresponding to distortions of the inorganic lattice. We hope that these findings lead to a more complete understanding of the ultrafast lattice response to transient local fields and its contributions to charge carrier screening.