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HL: Fachverband Halbleiterphysik
HL 25: Perovskite and photovoltaics I (joint session HL/CPP)
HL 25.3: Vortrag
Dienstag, 17. März 2020, 10:00–10:15, POT 251
Ultrafast Charge Carrier Relaxation in Inorganic Halide Perovskite Single Crystals Probed by 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
In recent years, halide perovskites have become one of the most intensely studied semiconductors for the development of optoelectronic devices. Regardless, the fundamental understanding of their optical and electronic properties still remains limited. To investigate the ultrafast dynamics of optical excitations we performed pump-probe and two-dimensional electronic spectroscopy (2DES) on CsPbBr3 single crystals with 10 fs time resolution [1]. While pump-probe spectra show a single bleaching feature near the band edge at 2.4 eV, 2DES maps reveal a more rich structure. In addition to a diagonal exciton bleaching peak, free carrier signatures in form of an elongated cross peak along the excitation axis appear. The separation of exciton and free carrier contributions allows to derive a rapid cooling rate of ~3 meV/fs, indicating a strong electron-phonon coupling. The experimental findings are supported by theoretical simulations based on semiconductor Bloch equations. Our results suggest that strong electron-phonon couplings may substantially contribute to the unusual optoelectronic properties of perovskites. [1] Nguyen, X.T., et al., JPCL, 10, p. 5414-5421, 2019.