Regensburg 2019 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 40: Perovskite and Hybrid Photovolatics I (joint session HL/CPP)
HL 40.12: Talk
Thursday, April 4, 2019, 12:30–12:45, H36
Ultrafast two-dimensional electronic spectroscopy of CsPbBr3 perovskite crystals — •Xuan Trung Nguyen1, Daniel Timmer1, Yevgeny Rakita2, David Cahen2, Antonietta De Sio1 und Chirstoph Lienau1 — 1Institut für Physik, Carl von Ossietzky Universität Oldenburg, Germany — 2Weizmann Institute of Science, Israel
Halide perovskites are attractive as cost-effective materials for developing highly efficient solar cells. Many research discussed about generation of excitons and free charges in halide perovskites under optical excitation. However, the role of excitons and their interplay with free charges for the optoelectronic and transport properties is not yet clear. Here we use two-dimensional electronic spectroscopy (2DES), with 10-fs-time resolution, to study the initial dynamics of optical excitations in single crystals of CsPbBr3. Upon excitation, we observe bleaching of the exciton resonance as diagonal peak and a cross-peak suggesting their interaction with free charges. Interestingly, the exciton peak vanishes within only ~20 fs and an intense elongated cross-peak persists for several ps. These results suggest efficient screening of exciton by free charges and highlight the importance of many-body interactions in the ultrafast dynamics of halide perovskites crystals.