Polymer light-emitting devices: promises, prospects-and problems

Summary form only given. Light-emitting devices made from conducting polymers offer attractive advantages. These include the fabrication of uniform areas of light on flexible substrates, with a variety of colours, using thin films of semiconducting and luminescent polymers cast from solution. The status of the science and technology will be summarized with emphasis on recent progress using two different device configurations: tunneling injection light-emitting diodes (LEDs) and light-emitting electrochemical cells (LECs). The latter is a new device configuration for light emission film electroactive polymers. In these LECs, a p-n junction diode is created in-situ through simultaneous p-type and n-type electrochemical doping on opposite sides, respectively, of a film of conjugated polymer which contains added electrolyte to provide the necessary counterions for doping. LECs have been fabricated which operate by the proposed electrochemical oxidation-reduction mechanism; blue, green and orange emission are obtained with turn-on voltage close to the bandgap of the emissive material.