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 subt le chemical modification of the precursor polymer. Examples of the uno riented fully conjugated material exhibit room temperature optical abs orption spectra (uncorrected for reflectivity) which have a peak in ab sorption at 2.45 eV with subsidiary shoulders at higher photon energie s. The absorption maximum is red-shifted with respect to previously ob served values. Luminescence spectra of these samples recorded at 10K a re complementary with a peak in emission at 2.38 eV and accompanying s ubsidiary maxima at lower energies. The peaks in absorption and emissi on are identified as the transitions between the vibrational ground st ates of the electronic and the first excited singlet states which we t erm the (0,0) transitions.