Progress towards stable blue light-emitting polymers

New routes have been developed for the synthesis of blue-emitting conjugated polymers designed to show stable blue-emission in LEDs. Fluorenes bearing polyphenylene dendrimer side-chains have been made by a new route in which the dendrimer substituents are built up on a biphenyl which is then ring-closed to give the fluorene. This route can be used to make fluorenes with a range of functionalised first and second generation dendrimer substituents, as monomers for new blue-emitting polymers. Polyindenofluorenes bearing aryl substituents have been made and found to display much stabler blue-emission than previous polyindenofluorenes.