High Performance Organic Light-emitting Devices with Doped Indium-tin-oxide Anodes

High performance organic light-emitting devices (OLEDs) with high luminance and high luminance efficiency have been fabricated by doping indium-tin-oxide (ITO) with Hf and V. The enhanced performance was attributed to the work functions (WF) of the ITO anode been modified by deposition of a thin (15 nm) Hf or V-doped ITO overlayer. The WF values were varied from 5.0 to 5.4 eV by doping different concentrations of Hf or V into the ITO overlayer. A luminance of 1000 cd/m2 at 6.8 V was obtained in the device with the V-doped ITO overlayer, and a luminance efficiency of 14 cd/A was achieved in the device with the Hf-doped ITO overlayer. The high performance of the OLED is believed due to the reduction of the hole injection barrier resulted from the work function modification of the ITO overlayer.