Electron injection polymer for polymer light-emitting diodes

Abstract

We report the use of an oxadiazole-containing polymer, poly(phenylene-1,3,4-oxadiazole- phenylene-hexafluoroisopropylidene) (PPOPH), as the electron injection layer in polymer light-emitting diodes. By introducing a PPOPH layer between the cathode (aluminum) and the luminescent polymer (poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene), the device performance was significantly improved; the quantum efficiency increased by a factor of 40, close to that of the same device using calcium as the cathode. By utilizing a porous polyaniline network electrode as the anode, the operating voltage was lowered by a factor of 2 with turn on at ∼5×105 V/cm.