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DF: Fachverband Dielektrische Festkörper

DF 10: Focus: Spatio-Temporal Multiscale Optical Spectroscopy Meets Functional Materials
(DF with O, CPP)

DF 10.1: Topical Talk

Mittwoch, 22. März 2017, 09:30–10:00, GER 37

Mobile electronic excitations studied by ultrafast spectroscopy — •Stefan Lochbrunner, Franziska Fennel, Steffen Wolter, and Tim Völzer — Institute of Physics, University of Rostock, Albert-Einstein-Str. 23, 18059 Rostock, Germany

The design of materials with specific photonic properties attracts currently intense scientific attention since they are the basis for many future applications in the fields of solar cells, detectors or light emitting devices. Understanding the behavior of light induced excitations in the materials is crucial for developing promising strategies. We apply time resolved spectroscopy on time scales ranging from femto- to milliseconds to characterize the sequence of processes and appearing species which result from the absorption of light. Two examples are presented in the talk. The migration of excitons due to Förster energy transfer is studied using a guest-host system based on dye molecules incorporated with a high concentration in PMMA. We characterized the influence of energetic disorder on the exciton mobility and developed a modified Förster theory which takes this effect correctly into account [1]. The dynamics of charge recombination in transition metal dichalcogenides is investigated by means of MoS₂. Evidence for defect assisted, bimolecular recombination is found by modelling the excitation dependent signal decay with corresponding rate equations.

[1] F. Fennel and S. Lochbrunner, Phys. Rev. B 92 (2015), 140301.