Spectroscopy and Transport of the Triplet Exciton in a Terthiophene End-Capped Poly(phenylene ethynylene)

Alison M. Funston, Eric E. Silverman, Kirk S. Schanze, and John R. Miller

J. Phys. Chem. B 110, 17736-17742 (2006). [Find paper at ACS Publications]

Abstract:

Triplet states of poly(phenylene ethynylene), ³PPE^*, not easily formed by direct photoexcitation, were produced by pulse radiolysis in toluene, along with triplet states of T₃PPE having terthiophene end-caps. Intense triplet-triplet absorption maxima, epsilon₆₈₀(³PPE^*) = 9.5 × 10⁴ M^-1 cm^-1 and epsilon₇₈₀(³T₃PPE^*) = 2.8 × 10⁴ M^-1 cm^-1 enable identification of these two species, which have triplet energies of 2.12 and 1.77 eV determined in bimolecular energy transfer equilibria. Bleaching of ground-state absorption measures ³PPE^* to be the delocalized over a 1.8-nm length. Triplet states formed in the PPE chains were transported to and trapped by the end caps in a time << 5 ns.