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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 25: Molecular Electronics and Excited State Properties II
CPP 25.2: Talk
Wednesday, March 20, 2024, 09:45–10:00, H 0111
Spatial Anisotropy of the Excitonic Coupling in β-Phase Zinc-Phthalocyanine Single Crystals — •Lisa Schraut-May1, Kilian Strauß1, Gabriele Tauscher2, Heinrich Schwoerer2, and Jens Pflaum1,3 — 1Experimental Physics VI, University of Würzburg, 97074 Würzburg — 2Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg — 3CAE Bayern, 97074 Würzburg
Since the anisotropic molecular packing in crystalline solids significantly influences their optical properties and their spatial dependence, the microscopic interplay between crystallographic structure, excitonic coupling and resulting optical characteristics defines an important research topic in organic opto-electronics [1]. In this context, metal-phthalocyanines (M-Pc) represent model systems, as they show different polymorphs and can be functionalized e.g. by gradual fluorination of their periphery [2]. In the case of ZnPc, the fluorination leads to changes in the unit cell parameters without strongly affecting the optical properties of the individual molecules. Here, we investigate single crystals of β-phase ZnPc by means of temperature dependent micro-photoluminescence (µ-PL). Besides discussing the microscopic coupling mechanisms associated with the temperature dependent structural changes and leading to superradiant PL enhancement in β-phase ZnPc at cryogenic temperatures, polarization dependent emission studies on various crystallographic facets prepared by microtomy of the crystals complete the picture of excitonic coupling along different crystallographic directions. [1] Hestand et al., Chem. Rev. (2018) [2] Rödel et al., J. Phys. Chem. C (2022)
Keywords: Phthalocyanine; Excitonic Coupling; Micro Photoluminescence; ZnPc; Organic Single Crystals