Berlin 2024 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 21: Optical Analysis of Thin Films

DS 21.1: Hauptvortrag

Freitag, 22. März 2024, 09:30–10:00, A 053

Spotlight on Crystalline Textured Anilino-Squaraine Thin Films featuring Multiple Davydov Splitting and Charge Transfer Excitons — •Manuela Schiek — JKU Linz, Austria

Quadrupolar anilino squaraine dyes exhibit distinct excitonic signatures in their visible absorption spectra due to strong intermolecular interactions. These excitons are a result of the spatial arrangement of the molecular backbones, which is steered by non-chromophoric terminal functionalization patterns. They can be of predominantly Frenkel-excitonic nature [1] or are hybridized with intermolecular charge transfer [2] and may feature an extraordinary strong excitonic circular dichroism [3]. Polarized spectro-microscopy and imaging ellipsometry are implemented to study the linear dichroism of crystalline domains, which is a direct probe for the excitonic transitions. Combined with structural analysis the orientation of molecules is traced and the excitonic bands are assigned by modelling. Especially imaging ellipsometry allows determination of the complete dielectric tensor [4], from which a multiple Davydov splitting including a dark state can be deduced for the case of an orthorhombic polymorph containing multiple non-equivalent molecules within the primitive unit cell.

[1] Balzer, Breuer, Witte, Schiek. Langmuir 38 (2022) 9266. [2] Balzer, Hestand, Zablocki, Schnakenburg, Lützen, Schiek. J. Phys. Chem. C 126 (2022) 13802. [3] Gavazzi, Schumacher, Grisanti, Anzola, Di Maiola, Zablocki, Lützen, Schiek, Painelli. J. Mater. Chem. C 11 (2023) 8307. [4] Funke, Duwe, Balzer, Thiesen, Hingerl, Schiek J. Phys. Chem. Lett. 12 (2021) 3053.

Keywords: Imaging Ellipsometry; Squaraine; Molecular Excitons; Davydov Splitting