SKM 2023 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 4: Perovskite and photovoltaics I (joint session HL/CPP)

HL 4.10: Vortrag

Montag, 27. März 2023, 12:15–12:30, JAN 0027

Fast diffusion of spin polarized excitons in bulk lead halide perovskites — •Sergiu Anghel¹, Dmitri R. Yakovlev¹, Dmitry N. Dirin², Maksym V. Kovalenko², Manfred Bayer¹, and Markus Betz¹ — ¹Experimentelle Physik 2, Technische Universität Dortmund, Otto-Hahn-Straße 4a, D-44227 Dortmund, Germany — ²Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich CH-8093, Switzerland

We investigate the spin diffusion of the free "hot" excitons in FA0.9Cs0.1PbI2.8Br0.2 bulk lead halide perovskite crystal at cryogenic temperatures by employing ultrafast time- and spatial-resolved magneto-optical Kerr microscopy. We measure the spin diffusion coefficient (D_s) of the free excitons of D_s~50 cm^2/s , which is a very surprising outcome, especially in the light of the recent results obtained on bulk or two-dimensional perovskites [1,2], where D_s is at least two orders of magnitude lower. D_s shows a roughly linear dependence on pump energy whereas the dependence on pump power is much more intricate - after a certain pump power threshold we observe an anomalous, nonlinear spatial dependence of D_s. We discuss our findings in view of efficient exciton-phonon coupling and Auger processes.

[1] A. Baldwin, G. Delport, K. Leng, R. Chahbazian, K. Galkowski, K. P. Loh, and S. D. Stranks, J. Phys. Chem. Lett. 12, 4003 (2021). [2] S. D. Stranks, G. E. Eperon, G. Grancini, C. Menelaou, M. J. P. Alcocer, T. Leijtens, L. M. Herz, A. Petrozza, and H. J. Snaith, Science 342, 341 (2013).