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Phase Transition Behavior and Molecular Orientation of Oligo(9,9′‐dioctylfluorene‐ alt ‐bithiophene)
Author(s) -
Li Na,
Zhang Xiaojie,
Geng Yanhou,
Su Zhaohui
Publication year - 2008
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200800167
Subject(s) - rubbing , materials science , annealing (glass) , polyimide , oligomer , thin film , conjugated system , molecule , glass transition , phase transition , polymer chemistry , crystallography , polymer , chemical engineering , composite material , nanotechnology , layer (electronics) , chemistry , organic chemistry , condensed matter physics , physics , engineering
Abstract A novel conjugated oligomer, oligo(9,9′‐dioctylfluorene‐ alt ‐bithiophene) (OF8T2), was found to exhibit a unique phase transition between crystalline and liquid‐crystalline states, and a liquid‐crystalline glass was easily generated, offering better TFT device performance. In thin films, upon annealing the OF8T2 molecules oriented preferentially with their planes of conjugation being normal to the substrate, and both film thickness and annealing temperature were critical to the film morphology and the molecular orientation. When the OF8T2 film was deposited on a rubbed polyimide surface and annealed, the molecules aligned their long axes along the rubbing direction.