Synthesis and Characterization of Bis(3,4-ethylene-dioxythiophene)-(4,4‘-dialkyl-2,2‘-bithiazole) Co-oligomers for Electronic Applications

The synthesis and characterization of several co-oligomers, 5,5‘-bis(4,4‘-dialkyl-2,2‘-bithiazol-5-yl)-(3,4,3‘,4‘-bis(ethylenedioxy)-2,2‘-dithienyl) (AT2A), 5,5‘-bis(3,4-ethylenedioxythien-2-yl)-4,4‘-dibutyl-2,2‘-bithiazole (TBT), and 5,5‘-bis(3,4,3‘,4‘-bis(ethylenedioxy)-2,2‘-dithien-5-yl)-4,4‘-dibutyl-2,2‘-bithiazole (T2BT2) are described. The solid-state structure of AT2A features π-stacking with a short intermolecular distance of 3.5 A. In thin films, the π-stacks are parallel to the film substrate as determined by X-ray diffraction. The UV−vis spectra of AT2A films show features that are ascribed to the effects of π-stacking. In addition, all these co-oligomers, composed of donor−acceptor moieties, show lowered optical band gaps, mainly because of the low oxidation potential imparted by incorporation of the 3,4-ethylenedioxythiophene (EDOT) moiety. Cyclic voltammetry indicates that these co-oligomers can be either p-doped or n-doped, and the spectroelectrochemical measurements show that the AT2A film...