Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 14: Organic-inorganic hybrid systems and organic films II

O 14.8: Hauptvortrag

Montag, 12. März 2018, 17:15–17:45, MA 042

Spotlight on Excitonic Coupling in Textured and Polymorphic Anilino Squaraine Thin Films — •Manuela Schiek — Institute of Physics, University of Oldenburg, Germany

Squaraines are small molecular quadrupolar donor-acceptor-donor (D-A-D) chromophores absorbing in the red spectral range considered for application as photovoltaic materials [1, 2]. A prototypical anilino squaraine with branched alkyl side chains (SQIB) crystallizes into two polymorphic bulk structures with different intermolecular interaction schemes. However, both crystal phases support Davydov splitting and thus show pleochroic absorbance spectra. In spin-casted [3] and vapor deposited [4] thin films X-ray diffraction probes these two phases with a strongly preferred out-of-plane orientation directed by the annealing temperature or by the choice of growth substrate, respectively. Linear polarized spectro-microscopy recordings locate the spatial orientation of the transition dipole moments and allow assignment of the Davydov components. Combined with cross-polarized and atomic force microscopy we obtain a complete picture of molecular orientation and excitonic coupling within the distinct morphological features and relative to the substrate [3].

[1] D. Scheunemann et al., Appl. Phys. Lett. 111 (2017) 183502. [2] O.S. Abdullaeva, A. Lützen, K. Dedek et al., Langmuir 32 (2016) 8533. [3] F. Balzer, M. Silies, C. Lienau et al., Cryst. Growth Des. (2017) DOI: 10.1021/acs.cgd.7b01131. [4] T. Breuer, G. Witte et al., unpublished results.