title: Phosphorescence and triplet state energies of oligothiophenes.
abstract: The phosphorescence spectra of a series of small oligothiophenes (nT, n = 1-3) incorporating a variety of substituents, end cappers, and functional groups have been recorded for the first time using gated detection in combination with nanosecond excitation in frozen solution at 80 K. The vibrationally resolved emission spectra provide accurate estimates of the T(1) and S(1) levels, and the singlet-triplet energy gap. Theoretical quantum chemical calculations performed at the DFT (B3LYP/6-31G*) level reproduce all experimental trends accurately and provide quantitative description of the S(0)-T(1) energy difference. The geometry relaxation in the excited state shows that the "natural" size of the triplet exciton is about 3-4 thiophene units.
authors.affiliation: Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Dorothee
authors.initials: D
authors.lastname: Wasserberg
authors.forename: Philippe
authors.initials: P
authors.lastname: Marsal
authors.forename: Stefan C J
authors.initials: SC
authors.lastname: Meskers
authors.forename: René A J
authors.initials: RA
authors.lastname: Janssen
authors.forename: David
authors.initials: D
authors.lastname: Beljonne