Studies of a poly(phenylenevinylene) without C2h symmetry

We have investigated the photophysics of the luminescent polymer poly(1,3-phenylenevinylene-alt-2,5-dioctyloxy-1,4-phenylenevinylene) (1,3-PPV) by a variety of optical spectroscopies. The incorporation of alternating meta-phenylene and para-phenylene rings reduces the conjugation length with respect to poly(para-phenylene vinylene) derivatives. As a consequence, excited states are blue-shifted and the nonlinear susceptibility is reduced. The reduced symmetry of 1,3-PPV modifies optical selection rules, resulting in strong overlap of the fluorescence spectrum with excited state absorption by charged polarons.