Regensburg 2016 – scientific programme
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DS: Fachverband Dünne Schichten
DS 55: Organic Thin Films III
DS 55.10: Talk
Friday, March 11, 2016, 12:00–12:15, H8
µ-Photoluminescence studies on the interaction between charge carriers and excitonic states in organic semiconductors — •T. Ferschke1, N.H. Hansen1, T. Schmeiler1, and J. Pflaum1,2 — 1Experimental Physics VI, Julius Maximilian University, 97074 Würzburg — 2ZAE Bayern, 97074 Würzburg
Charge carrier – exciton interactions are of significant importance for the performance of organic opto-electronic devices.[1] Recently, it has been shown that the current density in an organic semiconducting matrix can be analyzed on nanometer length scales by means of the photoluminescence (PL) of single guest dye molecules.[2] Here, we transfer the aforementioned concept from single molecules to, technologically more relevant, molecular ensembles by utilizing µ-PL studies to characterize intentionally doped Tris(8-hydroxyquinolinato)aluminium (Alq3) organic light emitting diodes (OLEDs). For this purpose, Tetra-phenyldibenzoperiflanthene (DBP) was embedded as dopant (0.1 wt%) via vacuum deposition at vertically defined positions within the Alq3 emitting layer. Upon applying a negative bias to the Ca/Al cathode, we observe an effective reduction in the PL of DBP by up to 14%. Varying the vertical position of the dopant and performing a 2D µ-PL-mapping we gain comprehensive information on the static and dynamic charge carrier characteristics within the recombination zone. These data provide insights in the microscopic mechanisms governing the two competing processes of PL quenching and electroluminescence.
[1] N.H. Hansen, et al., Phys. Rev. B, 2013, 87, 241202(R)
[2] M. Nothaft, et al., ChemPhysChem, 2011, 12, 2590–2595