Molecular Orientation Control of Liquid Crystal Organic Semiconduc-tor for High Performance Organic Field Effect Transistors
- Journal
- ACS Applied Materials & Interfaces
- Date
- 2021.02.25
- Abstract
The control of molecular orientation and ordering of liquid crystal (LC) organic semiconductor (OSC) for high performance and thermally stable organic thin-film transistors (OTFTs) is investigated. A liquid crystalline molecule, 2-(4-dodecyl thiophenyl)[1]dibenzothiopheno[6,5-b:6’,5’-f]-thieno[3,2-b]thiophene (C12-Th-DBTTT) is synthesized, showing the highly ordered smectic X (SmX) phase, demonstrating molecular reorganization via thermal annealing. The resulting thermally evaporated polycrystalline film and solution-sheared thin film show high charge carrier mobilities like 9.08 cm2 V-1 s-1 and 27.34 cm2 V-1 s-1, respectively. Atomic force microscopy (AFM) and grazing-incidence X-ray diffraction (GIXD) analysis prove that the random SmA1-like structure (smectic monolayer) to the highly ordered SmA2-like structure (smectic bilayer) of C12-Ph-DBTTT is reorganized to the smectic bilayered structures (SmA2) at the crystal-SmX transition temperature region. Due to the strong intermolecular interactions between rigid DBTTT cores, the thin film devices of C12-Th-DBTTT show excellent thermal stability up to 300 ℃, indicating that LC characterization of conventional OSC materials can obtain the high electrical performance as well as superior thermal durability.
- Reference
- ACS Appl. Mater. Interfaces 13, 11125？11133 (2021)