Sulfonation and epoxidation of substituted polynorbornenes and construction of light-emitting devices

Efficient routes to sulfonation and epoxidation of the double bonds in a polynorbornene backbone have been found that do not interfere with side chain functional groups of interest for making light-emitting devices. Substituted norbornene monomers were prepared with ether or thioether linkages, which were stable to sulfonation. Oligomers (25mers or 50mers) of homo- and copolymers containing diphenylanthracene (for blue-light emission), oxadiazole (for electron transport), and p-triphenylene (for hole transport) side chains were prepared via ring-opening metathesis polymerization (ROMP) of the corresponding norbornene monomers. Sulfonation of the polynorbornene backbone yielded a polyanionic material that was suitable for creating films via sequential adsorption with the polycation, poly(allylamine HCl) (PAH). Devices with an indium tin oxide (ITO) anode and an aluminum cathode were constructed. A two-layer device comprised of a layer of diphenylanthracene/oxadiazole copolymer and a layer of p-triphenylene homopolymer shouted better performance in terms of efficiency and light output than a single layer of diphenylanthracene/oxadiazole. However, a single layer of polymer containing 9-mesityl-10-phenylanthracene gave the best performance, up to 21 nW and 0.3 nW/mA efficiency.