Intra-chain triplet-triplet annihilation and delayed fluorescence in soluble conjugated polymers

Pulse radiolysis has been used to generate high triplet populations on isol ated conjugated polymer chains in benzene solutions. This allows direct obs ervation of delayed fluorescence (DF) arising from intramolecular triplet-t riplet annihilation (TTA). In poly(2-methoxy,5-(2 ' -ethyl-hexyloxy)-p-phen ylenevinylene) the triplet lifetime at low triplet concentration is 90 mus which decreases to 15 mus as the number of triplets saturates at ca. 30 tri plets per chain. Analysis of the DF kinetics gives an upper limit of 1.5% f or the number of triplets that contribute to TTA. We also observed DF in a range of other conjugated polymers. (C) 2001 Elsevier Science B.V. All righ ts reserved.