Enhanced electrical properties of rigid-rod polymer incorporated with electroactive triarylamino moieties

Oxidatively stable and electrically insulating rigid-rod polymer poly(p-phe nylenebenzobisthiazole) (PBT), was incorporated with electroactive triaryla mino (TPA) moieties, (R)TPA-PBT with R = NMe2 and Me. Copolymers or homopol ymers were synthesized with various TPA fractions changing the polymers to segmentally rigid configuration, and fabricated into films. On cast films, x-ray scattering revealed that the copolymers were random copolymers, micro scopy showed "template effect'' from the rigid segments. Iodine activation of the incorporated polymers led consistently to more than five order-of-ma gnitude increases in electrical conductivity. The activated conductivity al so increased with TPA fraction. A conductivity value as high as 4.1 x 10(-4 ) S/cm was realized for the activated (NMe2)TPA-PBT homopolymer. However, t emporal stabilities were observed for the conductivity, which seemed to dep end on the polymer composition and film morphology. Spectroscopic examinati on detected no new electronic state generated by iodine doping. Instead, op tical absorbance was drastically increased for h nu greater than 2 eV with a change in film color. Both enhanced conductivity and absorbance were not exhibited by the iodine-activated PBT polymer. (C) 1999 American Institute of Physics. [S0021-8979(99)04001-3].