William J. Cumming

Control of Chromophore Length in Electroluminescent Polymers. Part II. Mainchain Polymers

Abstract Electroluminescence emission has been demonstrated in mainchain polyesters and a structurally analogous polyamide. High molecular weight polyesters were synthesized by condensation of a dihydroxy functionalized, substituted, phenylene vinylene analogue, e.g., the lumo-phore, with a variety of dicarboxylic acid chlorides. The structure and hence the conjugation length of the emitting comonomer was predetermined prior to polymerization. Since the diacid moieties did not contribute to the conjugation length and hence the emission wavelength, the structure of the diacid was determined on the basis of its ease of synthesis, reactivity, and solubilizing ability in the final polymer. In each of the polyesters the electroluminescence wavelength of light-emitting diodes made from these polymers was similar to their photoluminescence emission spectrum in solution and the solid state at room temperature. The emission wavelengths ranged from blue to green. The polyamide exhibits a very broad band, nearly whi...

Light Emitting Diodes from Polymers with Luminescent Side Chains

Introduction: Organic electroluminescence (EL) has been intensely explored due in part to its application in flat panel display technology.1-3 It is hoped that organic materials, fluorescent dyes and polymers, will be fabricated into thin, large-area displays which can operate with low power consumption, high brightness and suitable lifetime. Recent advances indicate the great potential for organic light emitting diodes LEDs. Multi-layered devices created from vapor deposited fluorescent dyes have achieved high brightness and long lifetimes.3 The original problems associated with crystallization and diffusion seem to have been solved. In polymeric systems, high efficiencies, 4% internal efficiency, have been demonstrated by proper balance of charge injection in these systems.4