Photophysics of a poly(phenylenevinylene) with alternating meta-phenylene and para-phenylene rings

We have investigated the photophysics of the luminescent polymer poly(1,3-p henylenevinylene-alt-2,5-dioctyloxy-1,4-phenylenevinylene) by a variety of optical spectroscopies. The incorporation of alternating meta-phenylene and para-phenylene rings restricts conjugation with respect to poly(para-pheny lenevinylene) derivatives. As a consequence, excited states are blueshifted and the nonlinear susceptibility is reduced. Absorption by aggregates, whi ch can be obscured by scattering and interference, is clearly revealed by e lectroabsorption spectroscopy. The reduced symmetry of 1,3-PPV modifies opt ical selection rules, resulting in strong overlap of the fluorescence spect rum with excited state absorption by charged polarons.