The core of this paper concerns the use of an amorphous transparent conductive oxide (a-TCO), whose performance is on par with the classical indium tin oxide (ITO) films as a transparent contact in organic light emitting diodes (OLEDs). The main advantage of indium zinc oxide (IZO) films relies on their amorphous structure and high mobility that turns them likely to be used with high conductivity and high transmittance even at the infrared region. The mobility of IZO films (47.8 cm2 · V−1 · s−1) surpasses the one exhibited by ITO films (26.4 cm2 · V−1 · s−1), which along with its smoother surface and better current distribution plays an important role on OLEDs performance. Besides their similar turn-on voltage, the devices using IZO anodes exhibit higher power efficiency than the ITO ones, which is 66, 18, and 62% for orange, green, and blue OLEDs, respectively. These results suggest that IZO can potentially be applied as an anode in full color displays based on OLEDs.