Dresden 2014 – scientific programme
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DS: Fachverband Dünne Schichten
DS 27: Organic Thin Films II
DS 27.7: Talk
Wednesday, April 2, 2014, 16:30–16:45, CHE 91
Correlation between exciton diffusion and morphology in thin films of Diindenoperylene — •Alexander Steeger1, Anna Katharina Topczak1, and Jens Pflaum1,2 — 1Experimental Physics VI, University of Würzburg, 97074 Würzburg — 2ZAE Bayern, 97074 Würzburg
The exciton diffusion length (EDL) of organic thin films is known to strongly depend on the respective organic compound and can be attributed to a combination of intrinsic material properties and morphological impacts. In order to investigate the latter, we controlled the morphology of thin films of diindenoperylene (DIP) during evaporation by means of the substrate temperature TS. The EDL was extracted from film thickness dependent photoluminescence measurements in consideration of quenching quality, interference effects and interface roughness. In good agreement with atomic force microscopy and X-ray diffraction measurements showing an enhanced dewetting and significantly larger crystallite sizes at higher TS, polycrystalline DIP layers grown at TS = 300 K and 400 K exhibit high EDLs of 59 nm and 115 nm, respectively. In contrast, X-ray amorphous DIP deposited at TS = 100 K shows minor transport properties of excitons. This result emphasizes that exciton diffusion is substantially promoted by the long range order in molecular thin films. Financial support by the DFG focus program SPP 1355 is gratefully acknowledged.