Electrochemical and electroluminescent properties of random copolymers of fluorine- and alkoxy-substituted poly(p-phenylene vinylene)s

We report the synthesis and electroluminescent properties of random poly(phenylenevinylene) copolymers, carrying fluorine substitutions. In particular, we used 2,3,5,6-tetrafluoro-1,4-phenylenevinylene and 2-methoxy-5-(2‘-ethylhexyloxy)-1,4-phenylenevinylene moieties. The ratios of the two copolymer units were varied between 5:95 and 27:75. Electrochemical measurements showed an increase of the oxidation and a decrease of the reduction potentials of the copolymers upon increase of the fluorine content, as expected for the electron withdrawing effect of fluorine on the conjugated π-electron system. The copolymers showed emission in the red-orange region, with maximum photoluminescence efficiencies of 6.7%. We also observed lower turn-on voltages and higher electroluminescence efficiencies for lower fluorine contents.