Triplet exciton dynamics in conjugated polymer films
Hale, Gregory D.
Halas, Naomi J.
Master of Science
A thorough knowledge of the excited state dynamics in conjugated polymers is necessary for efficient use of these novel materials. Triplet excitons are believed to play an important role in conjugated polymer-based device operation. Triplet excitons are also believed to play a primary role in photo-oxidative degredation of polymer devices. Two-photon photoemission is used to probe triplet exciton relaxation dynamics in pristine conjugated polymer films and triplet-triple annihilation is determined to be an important deexcitation mechanism. Controlled photo-oxidation of conjugated polymer films is studied using two-photon photoemission. The triplet exciton-derived photoemission peak is observed to shift and narrow dramatically upon photo-oxidation. The peak narrowing is attributed to narrowing of the distribution of polymer conjugation lengths in the film. The peak shift is attributed to formation of defects at the ends of the polymer chains which change the average triplet exciton energy.
Polymer chemistry; Condensed matter physics; Optics