Berlin 2018 – scientific programme
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O: Fachverband Oberflächenphysik
O 77: Poster: Plasmonics and Nanooptics
O 77.5: Poster
Wednesday, March 14, 2018, 18:15–20:30, Poster A
STM-based time domain analysis of exciton generation in thin C60 films in the limit of single charge injection. — •Anna Rosławska1, Pablo Merino1, Christoph Große1,2, Christopher Leon1, Markus Etzkorn1, Klaus Kuhnke1, and Klaus Kern1,3 — 1Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany — 2NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK — 3École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
The performance of organic light emitting diodes is controlled by charge and exciton dynamics which can be probed by time-resolved spectroscopies. Many methods, however, are sensitive only to mesoscopic transport properties for large charge density distributions. Here, we explore locally the single charge and single exciton regime using time-resolved scanning tunneling microscope-induced luminescence (TR-STML). We study excitonic emission centers (ECs) in a model system of C60 thin films on Au(111). ECs exhibit single photon emission due to single exciton trapping near structural defects. We apply 100 ns voltage pulses to turn the photon emission from the EC on and off and record time-resolved electroluminescence as a function of tip-sample distance. The observed dynamics is due to single electron and single hole injection and can be analyzed by employing a kinetic model which perfectly fits the recorded transients. The electric field dependence of the obtained time constants allows characterizing the energy barrier for electron injection at the C60 - Au(111) interface.