Dresden 2017 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 23: Plasmonics and Nanooptics II: Light-Matter Interaction
HL 23.4: Talk
Monday, March 20, 2017, 15:45–16:00, TRE Ma
Charge dynamics in organic materials imaged with nanosecond and nanometer resolution. — •Anna Rosławska1, Pablo Merino1, Christoph Große1,2, 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 dynamics of charges and bound pairs of charge carriers (excitons) determines the performance of organic optoelectronic devices, such as light emitting diodes or solar cells. Precise nanoscale characterization of light emission at the nanosecond timescale can help to improve the efficiency of such devices. Here, by using low-temperature Scanning Tunneling Microscopy-induced Luminescence (STML) we probe the charge dynamics on defect-related light emission centers in C60 thin films. We apply 100 ns long square voltage pulses [1] to the tunnel junction and record transients of the emitted light with sub-nanosecond resolution as a function of injection current and lateral distance from the emission center. Analysis of luminescence transients discloses time constants ranging from 5 ns to 50 ns depending on the position in space. They can be attributed to hole and electron injection rates to the defect state. Our approach allows mapping the transients on a grid and therefore obtaining light intensity videos with sub-nanosecond time resolution at the ultimate molecular scale.
C. Große, et al., Appl. Phys. Lett., 103, 183108 (2013)