ESR study of singlet oxygen generation and its behavior during the photo-oxidation of P3HT in solution

Generation of 1O2 from poly-(3-hexylthiophene) (P3HT) irradiated in the presence of O2 in chlorobenzene was investigated using ESR measurement, employing 2,2,6,6-tetramethylpiperidine (TEMP) as a spin trap. 1O2 was found to be formed with O2ˉ being produced in parallel at a branching ratio of 99:1. Additionally, the reaction of P3HT with 1O2 was investigated using an endoperoxide as the 1O2 source in CCl4 by MALDI–TOF MS measurement. The upper limit of the rate constant for the reaction of P3HT with 1O2 was estimated using a kinetics simulation. These findings raise the understanding of the photo-oxidative degradation of P3HT.