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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 53: Perovskite and photovoltaics II (joint session HL/CPP)
CPP 53.1: Vortrag
Dienstag, 17. März 2020, 14:00–14:15, POT 251
Temperature-dependent exciton-phonon coupling in CsPbBr3 crystal using ultrafast two-dimensional electronic spectroscopy — •Xuan Trung Nguyen1, Daniel Timmer1, Yevgeny Rakita2, David Cahen2, Alexander Steinhoff3, Frank Jahnke3, Christoph Lienau1, and Antonietta De Sio1 — 1Institut für Physik, Carl von Ossietzky Universität, Germany — 2Weizmann Institute of Science, Israel — 3Institut für Theoretische Physik, Universität Bremen, Germany
Halide perovskites (HaPs) are promising semiconductor materials for developing efficient solar cells. It is, however, still debated how the unusual electron-lattice couplings in these materials affect their optical and electronic properties. Here, we investigate the temperature dependence of near band gap optical transitions in CsPbBr3 single crystals by 10fs-time-resolution two-dimensional electronic spectroscopy (2DES). At room temperature, the 2DES maps show rapid charge carrier relaxation within the continuum and the concurrent build-up of exciton screening by free carriers on a <30fs time scale [1]. At 70K, we detect large, persistent oscillations of both amplitude and resonance energy of the exciton peak with periods corresponding to the phonon modes of the lead-halide sublattice. Our results point to strong exciton-phonon couplings and to the importance of many-body interactions for the optical and transport properties in HaPs.
[1] Nguyen, X.T., et al., JPCL, 10, p. 5414-5421, 2019.