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HL: Fachverband Halbleiterphysik

HL 12: Charge transfer effects in molecular materials I (CPP, jointly with BP, DS, HL)

HL 12.2: Vortrag

Montag, 11. März 2013, 12:30–12:45, H1

Mixing-induced anisotropic correlations in molecular crystalline systems: Rationalizing the behavior of organic semiconductor blends — •Katharina Broch, Antje Aufderheide, Jiří Novák, Alexander Hinderhofer, Rupak Banerjee, Alexander Gerlach, and Frank Schreiber — Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen

Binary mixtures of organic semiconductors (OSCs) have recently become an important field of research, as they find applications in opto-electronic devices [1]. In these systems, the mixing (intermixing vs. phase separation) and ordering behavior is crucial, since it affects the optical and electronic properties including the degree of charge-transfer (CT). We present a comprehensive study of binary mixtures of the three prototypical OSCs pentacene (PEN), perfluoropentacene (PFP) and diindenoperlyene (DIP) in all possible combinations [1,2,3]. Using X-ray reflectivity and grazing incidence X-ray diffraction we investigate the structural properties of the mixed films as well as their impact on the optical spectra obtained by spectroscopic ellipsometry. For PEN:DIP we find an anisotropic ordering behavior, comparable to that observed in some liquid crystals, which is fundamentally new for OSCs [2]. The influence of sterical compatibility and the strength of the intermolecular interactions on the mixing and ordering behavior in the different blends will be discussed by extending a conventional mean-field model [1]. [1] A. Hinderhofer and F. Schreiber, Chem.Phys.Chem., 13, 628 (2012); [2] A. Aufderheide et al., Phys.Rev.Lett., 109, 156102 (2012); [3] J. Reinhardt et al., J.Phys.Chem. C, 116, 10917 (2012)