Solution processed polymer light-emitting diodes utilizing a ZnO/organic ionic interlayer with Al cathode

Abstract

This letter reports polymer light-emitting diodes that employ a soluble zinc oxide (ZnO) nanoparticle (NP) and organic ionic interlayer as an electron-injection layer exhibits remarkable enhancement of device performance despite aluminum cathode. The ionic solution infiltrated into ZnO NP layer, which contains poly (ethylene oxide) and tetra-n-butylammonium tetrafluoborate, significantly lowers the large electron-injection barrier by forming a permanent interfacial dipole. The polymer, phenyl substituted poly(para-phenylene vinylene) known as "Super Yellow," yellow light-emitting diodes employing the ZnO NP and ionic interlayer show a maximum efficiency of 6.3 cd/A at a 1209 cd/m(2) and 5.4 V. The maximum brightness of the device reached 24 000 cd/m(2) at 9 V. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3526308]