Green-Emitting PPE−PPV Hybrid Polymers:  Efficient Energy Transfer across them-Phenylene Bridge

Novel π-conjugated polymers (7) consisting of both poly(phenylenevinylene) (PPV) and poly(phenyleneethynylene) (PPE) blocks are synthesized by using a combination of Heck-type coupling and Horner−Wadsworth−Emmons condensation reactions. These polymers have well-defined chemical structure (−Ph−C⋮C−Ph−C⋮C−Ph−CC−Ph−CC−)n, in which phenyl rings are linked alternately at meta and para positions. 13C NMR spectroscopy further confirms the structural regularity of the polymers. The degree of polymerization (DP) is in the range 27−76. Resulting from efficient energy transfer from PPE block to PPV block, the PPV/PPE hybrid polymer emits light with the same color as poly[(m-phenylenevinylene)-alt-(p-phenylenevinylene)], 1. LED devices of ITO/PPV/7/Ca and ITO/PEDOT/7/Ca configurations have been fabricated, which give green EL emission with external quantum efficiency of 0.15% for the former and 0.32% for the latter.