Poly(p-pyridine)- and poly(p-pyridyl vinylene)-based polymers: Their photophysics and application to SCALE devices

Photophysics and light-emitting device applications of poly(p-pyridine)- and poly(p-pyridyl vinylene)-based polymers are presented. Extensive time-resolved (ps to ms) photoluminescence, stimulated emission and photoinduced absorption studies of solutions, powders and films demonstrate that the primary photoexcitation of these polymers is an intrachain singlet exciton. The presence of (n,pi*) states leads to enhanced intersystem crossing to triplet excitons for the powder form, while aggregate formation plays a key role in the films. Polarons are important at longer times. These polymers were used to fabricate 'conventional' polymer light-emitting diodes. In addition, these polymers were used to demonstrate a novel light-emitting structure, the symmetrically configured a.c. light-emitting (SCALE) device. These new devices have potential advantages in their use with high workfunction electrodes, such as gold, and also in their a.c. operation.