Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 20: Organic Semiconductors: Transistors and OLEDs
HL 20.10: Vortrag
Dienstag, 23. März 2010, 12:00–12:15, H15
Probing charge carrier dynamics in conducting polymers using single molecules as sensors — •Maximilian Nothaft1, Steffen Höhla2, Aurélien Nicolet3, Jens Pflaum4, Fedor Jelezko1, and Jörg Wrachtrup1 — 13. Phys. Ins., Univ. Stuttgart — 2Chair of Display Technology, Univ. Stuttgart — 3MoNOS, Huygens Laboratory Leiden — 4Exp. Phys. VI, Univ. Wuerzburg and ZAE Bayern
Doping of conducting polymers by guest molecules is widely applied in organic light emitting devices to improve their efficiency. By reducing the concentration of suited guest molecules it becomes possible to study the dynamics of single molecule emitters using confocal microscopy.
In our contribution we discuss the optical properties of single Dibenzoterrylene dye molecules dispersed in an OLED consisting of PPV as host material. It will be shown how to prepare devices of photostable single molecules in PPV emitting a constant flux of single photons at room temperature by excitation from a Ti:sapphire laser.
By simultaneous laser excitation and electrical operation it is possible to detect the effect of injected charge carriers on the dynamics of single quantum emitters. Since the ratio of singlet to triplet exciton formation in the device is 1:3, this leads to an effective pumping to the triplet state of the single molecule thereby reducing its fluorescence intensity. Modeling this process it becomes possible to associate the reduced fluorescence intensity with the local current density at the position of the molecule. This correlation enables us to optically probe the current density in an OLED with nm spatial resolution.