Efficiency Enhancement and Color Stabilization in Organic Light-Emitting Devices Utilizing a Fullerene-Polymer Composite Layer Acting as a Hole Transport Layer

Abstract

The electrical and optical properties of organic light-emitting devices (OLEDs) utilizing a nanopolymer composite layer consisting of fullerene (C-60) and poly(2-methoxy-5-[2'-ethylhexyloxyl-p-phenylenevinylene) (MEH-PPV) were investigated. The current density of devices with a C-60/MEH-PPV composite hole transport layer (HTL) was larger than that of devices without a composite HTL owing to the enhancement in the hole injection and transport. The luminance efficiency of the OLEDs utilizing a C-60/MEH-PPV composite layer was significantly enhanced owing to an increase in the conductivity of the C-60/VIEH-PPV composite HTL. The recombination region in the center of the emitting layer for the device with a C-60/MEH-PPV composite layer decreased the variation of color coordinates and enhanced the color stability, resulting in the realization of the highly efficient device.