Interface Induced Crystal Structures of Dioctyl-Terthiophene Thin Films
| Autor: | Armin Moser, Oleg Konovalov, Gabin Gbabode, Oliver Werzer, Roland Resel, Jiri Novak, Nicolas Boucher, Johann P. de Silva, Michele Sferrazza, Yves Geerts |
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| Rok vydání: | 2012 |
| Předmět: |
Diffraction
Materials science Surface Properties Molecular Conformation Thiophenes Crystal structure Crystallography X-Ray Microscopy Atomic Force Phase Transition Crystal chemistry.chemical_compound Terthiophene Metastability Phase (matter) Electrochemistry Molecule General Materials Science Thin film Spectroscopy Calorimetry Differential Scanning Temperature Surfaces and Interfaces Silicon Dioxide Condensed Matter Physics Liquid Crystals Crystallography Semiconductors chemistry Thermodynamics Crystallization |
| Zdroj: | Langmuir. 28:8530-8536 |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/la301213d |
| Popis: | Temperature dependent structural and morphological investigations on semiconducting dioctyl-terthiophene (DOTT) thin films prepared on silica surfaces reveals the coexistence of surface induce order and distinct crystalline/liquid crystalline bulk polymorphs. X-ray diffraction and scanning force microscopy measurements indicate that at room temperature two polymorphs are present: the surface induced phase grows directly on the silica interface and the bulk phase on top. At elevated temperatures the long-range order gradually decreases, and the crystal G (340 K), smectic F (348 K), and smectic C (360 K) phases are observed. Indexation of diffraction peaks reveals that an up-right standing conformation of DOTT molecules is present within all phases. A temperature stable interfacial layer close to the silica-DOTT interface acts as template for the formation of the different phases. Rapid cooling of the DOTT sample from the smectic C phase to room temperature results in freezing into a metastable crystalline state with an intermediated unit cell between the room temperature crystalline phase and the smectic C phase. The understanding of such interfacial induced phases in thin semiconducting liquid crystal films allows tuning of crystallographic and therefore physical properties within organic thin films. |
| Databáze: | OpenAIRE |
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