SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 32: Molecular Electronics and Excited State Properties (joint session CPP/TT)
TT 32.8: Vortrag
Mittwoch, 29. März 2023, 11:30–11:45, GÖR 226
Influence of Fluorination on the Temperature Dependent Optical Transition in β- Phase ZnPc Single Crystals — •Lisa Schraut-May1, Kilian Strauß1, Sebastian Hammer2, Kilian Frank3, Bert Nickel3, and Jens Pflaum1 — 1Experimental Physics VI, University of Würzburg — 2Departments of Physics and Chemistry, McGill University, Montreal, Canada — 3Department of Physics, LMU Munich
The possibility of fluorination renders zinc phthalocyanine (ZnPc) an excellent model system to study the interplay between molecular packing and opto-electronic properties [1]. Here, we conduct temperature as well as polarisation dependent photoluminescence (PL) studies on β-phase ZnPc single crystals with different degrees of fluorination to modify the microscopic packing and, thus, the interaction between the molecules. For plain ZnPc an exceptionally sharp PL peak can be observed at temperatures below 100 K, which can be attributed to a superradiant enhancement [2]. Since this coherent coupling between several molecules strongly depends on the intermolecular spacing, we show, that this phenomenon can be steered by the fluorination of the molecules involved. We interpret the resulting PL signal and its temperature dependence in combination with X-ray studies by a model based on coupled excitons whose coupling is affected by the spatial anisotropy of the thermal contraction of the crystal lattice.
We thank the Bavarian research network SolTech for financial support. [1] Rödel et al., J. Phys. Chem. C (2022) [2] Hestand et al., Chem. Rev. (2018)