title: Synthesis, structural characterization, and unusual field-effect behavior of organic transistor semiconductor oligomers: inferiority of oxadiazole compared with other electron-withdrawing subunits.
abstract: A new series of heterocyclic oligomers based on the 1,3,4-oxadiazole ring were synthesized. Other electron-deficient cores (fluorenone and fumaronitrile) were introduced to investigate the oligomers as n-channel materials. The physical properties, thin film morphologies, and field-effect transistor characteristics of the oligomers were evaluated. Thin films were deposited at different substrate temperatures and on variously coated Si/SiO(2) for device optimization. Contrary to our expectations, the thin film devices of 4 revealed p-channel behavior, and the average hole mobility was 0.14 cm(2) V(-1) s(-1) (maximum value 0.18 cm(2) V(-1) s(-1)). Compound 11 is the first example of an oxadiazole-containing organic semiconductor (OSC) oligomer in an n-channel organic field-effect transistor (OFET) and shows moderate mobilities. Non-oxadiazole-containing oligomers 9 and 12 showed n-channel OFET behavior on hexamethyldisilazane-treated and Cytop spin-coated SiO(2) in vacuum. These are the first fluorenone- and fumaronitrile-based n-OSCs demonstrated in transistors. However, oxadiazole-core materials 14 and 16 were inactive in transistor devices.
authors.affiliation: Department of Materials Science and Engineering and Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA.
authors.forename: Taegweon
authors.initials: T
authors.lastname: Lee
authors.forename: Chad A
authors.initials: CA
authors.lastname: Landis
authors.forename: Bal Mukund
authors.initials: BM
authors.lastname: Dhar
authors.forename: Byung Jun
authors.initials: BJ
authors.lastname: Jung
authors.forename: Jia
authors.initials: J
authors.lastname: Sun
authors.forename: Amy
authors.initials: A
authors.lastname: Sarjeant
authors.forename: Ho-Jin
authors.initials: HJ
authors.lastname: Lee
authors.forename: Howard E
authors.initials: HE
authors.lastname: Katz
mesh_terms: D004583:Electrons; D005449:Fluorenes / Q000737:chemistry; D005650:Fumarates / Q000737:chemistry; D010069:Oxadiazoles / Q000138:chemical synthesis / Q000737:chemistry*; D012666:Semiconductors; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D005449:Fluorenes; D005650:Fumarates; D010069:Oxadiazoles; D012822:Silicon Dioxide; C057444:fumaronitrile