EXTENDED PI-CONJUGATION IN POLY(P-PHENYLENEVINYLENE) FROM A CHEMICALLY-MODIFIED PRECURSOR POLYMER

We have developed a synthetic method that allows a controlled increase in the one-dimensional character of poly(p-phenylenevinylene) by subtle chemical modification of the precursor polymer. Examples of the unoriented fully conjugated material exhibit room temperature optical absorption spectra (uncorrected for reflectivity) which have a peak in absorption at 2.45 eV with subsidiary shoulders at higher photon energies. The absorption maximum is red-shifted with respect to previously observed values. Luminescence spectra of these samples recorded at 10K are complementary with a peak in emission at 2.38 eV and accompanying subsidiary maxima at lower energies. The peaks in absorption and emission are identified as the transitions between the vibrational ground states of the electronic and the first excited singlet states which we term the (0,0) transitions.