Electroluminescence from New Polynorbornenes That Contain Blue-Light-Emitting and Charge-Transport Side Chains

A blue-light-emitting electroluminescent polymer was prepared by ring-opening metathesis polymerization (ROMP) of a norbornene monomer that contains a diphenylanthracene chromophore as a side chain (λ max,em = 450 nm). Norbornene monomers also were synthesized that contain an oxadiazole (for electron transport) or a tertiary arylamine (for hole transport). Oligomers (25mers or 50mers) of homo- and copolymers ( M w / M n = 1.02−1.08) were prepared in toluene in 95−98% yield, employing Mo(N-2,6-C 6 H 3 - i -Pr 2 )(CHMe 2 Ph)(O- t -Bu) 2 as the initiator. Electroluminescent devices made with a single layer of substituted polynorbornene, an ITO anode, and an Al cathode were prepared first. Two-layer devices were then constructed in which the substituted polynorbornene was spin cast onto a 25-bilayer poly(phenylenevinylene) (PPV) heterostructure. The two-layer device performed best in terms of efficiency, light output, and threshold voltage.