ALIPHATIC PHENYLENE VINYLENE COPOLYMERS - TUNING THE COLOR OF LUMINESCENCE THROUGH CO-MONOMER FEED RATIOS

By introducing co-monomers with flexible linker groups into a step growth condensation route to poly(phenylene-alt-vinylene) (PPV), a series of solution-processible PPV copolymers is prepared. Peak photoluminescence of these copolymers systematically ranges from about 2.25 to 2.75 eV (yellow-green to blue), increasing in energy upon increasing flexible Linker content. Length of the Linker group does not significantly alter spectral properties but does influence solubility and film morphology. The statistical distribution of phenylene vinylene segments along the copolymer backbone is discussed in the context of the optical profiles expected. Quantitative quenching of the luminescence for the shortest phenylene vinylene segments strongly indicates that crossover of excited states is occurring. The trapping and recombination of these excited states is occurring on lower-energy ''islands'', confirmed to be the longer phenylene vinylene segments, which serve as ideal recombination sites for photogenerated species.