The phase-segregated structure and the electrical properties of thin film blends of the small-molecule semiconductor fluorinated 5,11-bis(triethylsilylethynyl) anthradithiophene with insulating binder polymers were studied for organic thin film transistor applications. Three binders were evaluated: amorphous atactic poly(α-methylstyrene), poly(methylmethacrylate) and semicrystalline syndiotactic polystyrene. The binder polymers induce significant differences in miscibility, segregation behavior and the resultant device performance, which can be explained in terms of different polarities or solidification rates. The vertical stratification and molecular orientations of the blend films were characterized by complementary techniques including grazing incidence X-ray diffraction, neutron reflectivity, variable angle spectroscopic ellipsometry and near edge X-ray absorption fine structure spectroscopy. The segregated film structure, crystalline order and molecular orientation explain significant differences in the electrical performance of these blend films in solution-processed, bottom-gate, bottom-contact transistors.
Citation: Journal of the American Chemical Society
Pub Type: Journals
organic electronics, neutron reflectivity, spectroscopic ellipsometry, organic transistor, polymer