ABSORPTION AND LUMINESCENCE OF PYRIDINE-BASED POLYMERS

We summarize the low energy photophysics of the pyridine-based polymer s poly(p-pyridine)(PPy), poly(p-pyridyl vinylene) (PPyV) and copolymer s made up of PPyV and poly(p-pheneylene vinylene) (PPyVPV). The absorp tion and luminescence properties are morphology dependent. The primary photoexcitations within these polymers are singlet excitons which may emit from individual chains following a random walk to lower energy s egments, depending upon the excitation energy. Films display redshifte d absorption and emission properties with a decrease in photoluminesce nce efficiency which can be attributed to aggregate formation in compa rison to powder and solution forms. Photoinduced absorption (PA) studi es show direct conversion of singlet to triplet excitons on the ps tim e scale. Polaron signatures and the transition between triplet exciton states are seen in powder forms using ms PA techniques. Film forms di splay only a polaron signature at millisecond times indicating that mo rphology plays a key role in the long-time photophysics for these syst ems. Photoluminescence detected magnetic resonance studies also have s ignatures due to both polarons and triplet excitons. The size of the t riplet exciton is limited to a single ring suggesting that the triplet exciton may be trapped by extrinsic effects.