New soluble poly(2,3-diphenylphenylene vinylene) derivatives for light-emitting diodes

Abstract

Soluble poly(2,3-diphenylphenylene vinylene) (DP-PPV) derivatives, poly(2,3-diphenyl-5-(4-heptyloxy-4'-oxytrimethylenediphenyl)phenylene vinylene) (P1), poly(2,3-diphenyl-5-[4-(4-pentylcyclohexyl)phenoxyl-propyl-p-phenylene vinylene) (P2) and poly(2,3-diphenyl-5-(2-(1, 4, 5-triphenyl-1H-2-imidazoloyl)-1-oxytrimethylene phenyl) phenylene vinylene) (P3), were synthesized. P1 and P2 contain liquid crystal side groups; while P3 contains a charge transport group. The polymers showed solid state UV-Visible absorption and photoluminescence in the range of 370-380 and 480-510 nm, corresponding to blue green emission. Similar to many other reported systems, the solution fluorescence spectra of P1 and P2 showed slight solvent dependency and blue-shifted with respect to those of the films. These were not the case for P3 which showed little solvent dependency and little blue shift in solution. Two-layer light-emitting devices with a simple ITO/PEDOT/polymer/Ca (Al) configuration were fabricated and characterized. (c) 2004 Elsevier B.V. All rights reserved.