PHOTOEXCITED STATES IN POLY-3-ALKYLTHIOPHENE SOLUTIONS

We present a study of the photoexcitations of poly-3-alkylthiophene solutions. Phototransients with lifetimes of 1 mu s-10 ms are observed by measuring the steady state and transient photoinduccd absorption on a good solvent solution. The long lived photoexcited states are assigned to charged species which are generated and recombine through a weak reversible polymer-solvent charge-transfer. A short lived photoinduced band at 1.65 eV is assigned to a dipole allowed triptet-triplet transition.