The X-band optically detected magnetic resonance of poly(3-hexylthiophene) and poly(3-dodecylthiophene) films and solutions are described and discussed. The photoluminescence-enhancing features include (i) a strong, ∼15-G-wide, asymmetric peak at g≃2.003; (ii) a weak peak at g≃4.07; and (iii) a weak, ∼800-G-wide structure around g≃2. It is believed that feature (i) results from polaron recombination, and the others from the decay of two distinct intrinsic triplet polaronic excitons. The levels of all are apparently close to the band edges.

• Received 18 June 1990

DOI:https://doi.org/10.1103/PhysRevLett.65.1140