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Polymorphism of terthio-phene with surface confinement.
Roland Resel1, Andrew O F Jones1, Guillaume Schweicher2,3
1Institut für Festkörperphysik, Technische Universität Graz, Petersgasse 16, Graz 8010, Austria.
Iucrj
|May 15, 2018
Summary
Researchers discovered a new terthio-phene polymorph using thermal gradient crystallization. This novel crystal structure exhibits a unique herringbone packing, adapting to flat glass substrates for dense interfaces.
Area of Science:
- Materials Science
- Crystallography
- Organic Electronics
Background:
- Polymorphism in thin films remains poorly understood.
- Terthio-phene is a molecule of interest for thin-film applications.
Purpose of the Study:
- To investigate the origin of unknown polymorphic phases in terthio-phene thin films.
- To characterize a newly discovered polymorph of terthio-phene.
Main Methods:
- Thermal gradient crystallization on glass-plate substrates.
- Specular X-ray diffraction for phase identification.
- Single-crystal X-ray diffraction for structure solution.
Main Results:
- Growth of plate-like terthio-phene crystalline domains (100 µm lateral size, few µm thickness).
- Confirmation of a new terthio-phene polymorph with a large unit-cell volume (42 independent molecules).
- Observation of a novel herringbone molecular packing motif adapted to the flat substrate surface.
Conclusions:
- The new packing motif involves 180° flipped molecules and disordered occupation.
- A densely packed interface between crystallites and the substrate is achieved.
- This study elucidates a new crystalline phase and packing mechanism in terthio-phene thin films.
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