Highly efficient blue phosphorescent polymer light-emitting diodes by using interfacial modification

Solution processed highly efficient blue electrophosphorescent polymer light-emitting diodes have been fabricated containing an oligo(ethylene oxide) (PEO-DME) additive to enhance the electroluminescence efficiency. The addition of PEO-DME at 5-10 wt % effectively lowers both the electron and hole injection barriers. The maximum current efficiency obtained was 26.5 cd/A at an emission brightness of 2500 cd/m(2). The high performance is due to (i) improved charge carrier injection at the interface resulting from specific interfacial interactions between PEO-DME and aluminum and (ii) improved charge carrier transporting ability and high electric field resulting from PEO-DME doping. (C) 2011 American Institute of Physics. [doi:10.1063/1.3593380]