Studies of a poly(phenylenevinylene) without C-2h symmetry

We have investigated the photophysics of the luminescent polymer poly(1,3-p henylenevinylene-alt-2,5-dioctyloxy-1,4-phenylenevinylene) (1,3-PPV) by a v ariety of optical spectroscopies. The incorporation of alternating metaphen ylene and para-phenylene rings reduces the conjugation length with respect to poly(para-phenylene vinylene) derivatives. As a consequence, excited sta tes are blue-shifted and the nonlinear susceptibility is reduced. The reduc ed symmetry of 1,3-PPV modifies optical selection rules, resulting in stron g overlap of the fluorescence spectrum with excited state absorption by cha rged polarons.