Triplet-state photoexcitations and triplet-energy transfer in poly(3-alkylthiophene)/C/sub 60/ solutions

Summary form only given. We present the first observation and characterization of a metastable triplet-state photoexcitation of poly(3-alkylthiophene), P3AT, in solution. The PIA spectrum of P3AT in various solvents reveals a strong band centered at 1.50 eV which is attributed to a dipole allowed triplet-triplet absorption. We find that the triplet state of P3AT lies 1.57-1.72 eV above the ground state. The, formation of charged polaronic and/or bipolaronic photoexcitations, is a minor process, compared to the generation of the metastable triplet state, even in solvents that favor electron transfer. The P3AT triplet-state photoexcitation exhibits an efficient energy transfer reaction to C/sub 60/.