Decoding Nonlinear Polarization Responses in Lead Halide Perovskites via Two-Dimensional Optical Kerr Spectroscopy
Sebatian F. Maehrlein a e, Prakriti P. Joshi a, Lucas Huber a, Feifan Wang a, Marie Cherasse a, Yufeng Liu a, Dominik M. Juraschek b c, Edoardo Mosconi d, Daniele Meggiolaro d, Filippo de Angelis d, X.-Y. Zhu a
a Department of Chemistry, Columbia University, US, Broadway, 3000, New York, United States
b Harvard University, Harvard John A. Paulson School of Engineering & Applied Sciences, US, United States
c ETH Zurich, Department of Materials Science, Switzerland, Switzerland
d Computational Laboratory for Hybrid/Organic Photovoltaics (CLHYO), CNR-SCITEC, Italy, Italy
e Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, Berlin, 14195, Germany
Proceedings of International Conference on Impedance Spectroscopy and Related Techniques in Metal Halide Perovskites (PERIMPED)
Online, Spain, 2020 October 6th - 7th
Organizers: Juan Bisquert, Bruno Ehrler and Eline Hutter
Oral, Sebatian F. Maehrlein, presentation 014
Publication date: 25th September 2020

The ultrafast polarization response to incident light and ensuing electronic excitations are essential to the outstanding optoelectronic properties of lead halide perovskites (LHPs). In recent studies, a dynamically disordered structure and anharmonic crystal lattice was suggested to be a key component for LHPs’ complex polarization dynamics [1], [2]. In this work, we develop a novel type of two-dimensional (2D) spectroscopy to spectrally resolve and disentangle contributions to the ultrafast optical Kerr-effect (OKE) in MAPbBr3 and its all-inorganic counterpart CsPbBr3. This technique allows us to energetically dissect broadband light propagation and dispersive polarization responses in the vicinity of the electronic bandgap. Light propagation in LHPs is in particular technologically relevant for solar cell, light modulation and LED applications due to stimulated emission, polariton condensation and photon recycling which may take place in the investigated spectral region [3], [4].  

In both LHPs, we find intense nonlinear mixing of anistropically propagating light fields, resulting in an oscillatory polarization response, which strongly depends on the crystallographic phase and the position of the electronic bandgap. Our findings moreover raise the awareness for anisotropic and nonlinear light propagation, complicating conventional time-resolved methods, such as transient absorption, two-dimensional electronic spectroscopy and (1D) OKE near resonances of the dielectric function. We further demonstrate the power of two-dimensional optical Kerr-effect (2D-OKE) and its temperature-dependent fingerprint to quantify the dispersion anisotropy of LHPs’ orthorhombic phase. In addition to revealing highly dispersive anisotropic light propagation and its nonlinear mixing, this study finally establishes a unified origin of ultrafast Kerr responses in single crystal LHPs near the optical bandgap.

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