High efficiency low operating voltage polymer light-emitting diodes with aluminum cathode

Abstract

By blending poly(ethylene glycol) (PEG) into an electroluminescence (EL) polymer, significantly enhanced EL efficiency in a polymer light-emitting diode (PLED) with aluminum electrode was achieved. An orange-color-emitting PLED with 10 wt % PEG blending achieved device efficiencies exceeding 2.6 cd/A for a wide range of bias voltage, which is more than two orders of magnitude higher than that of a similar PLED without the PEG blending. The enhanced efficiency was a result of the reduction of electron injection barrier height at the cathode–polymer interface. It is believed that interfacial interaction that is specific to Al plays an important role in the enhancement mechanism.