The preparation and characteristics of a transparent conducting indium zinc tin oxide (IZTO) anode for highly efficient phosphorescent organic light emitting diodes (OLEDs) is described. The resistivity and transmittance of the IZTO anode are comparable to reference In2O3 (ITO) anode films even though it was prepared at room temperature. In addition, the work function of the ozone-treated amorphous IZTO anode (5.12 +/- 0.02 eV) is much higher than that of ozone-treated reference ITO anodes (4.94 +/- 0.02 eV). The current-voltage-luminance characteristics and efficiencies of OLEDs prepared on the IZTO anode are critically dependent on the sheet resistance of the IZTO anode. Furthermore, both the quantum efficiency and power efficiency of the OLED fabricated on the amorphous IZTO anode are much higher than those of an OLED with the reference ITO anode due to the higher work function of the IZTO anode than those of conventional ITO anode. This indicates that IZTO is an alternative material for conventional ITO anodes used in OLEDs and flexible displays. (c) 2007 The Electrochemical Society.