Red and near infrared polarized light emissions from polyfluorene copolymer based light emitting diodes

Abstract
The authors report polarized red, electroluminescence peak at 705nm and near infrared, electroluminescence peak at 950nm , light emission from light emitting diodes based on two polyfluorene copolymers. The copolymers are synthesized from a fluorene monomer combined with donor-acceptor-donor comonomers and designed to have a low band gap and form birefringent liquid crystalline phases. Emission occurs from aligned thin films of polymer layers. The emissive layers are aligned by spin coating on a layer of rubbed conducting polymer poly(3,4-ethylene dioxythiophene)-poly(styrene sulphonate) and thermally converted into glassy nematic liquid crystalline state.