High-performance top-emitting white organic light-emitting devices

High-performance top-emitting white organic light-emitting devices (WOLED), using Al as the reflective bottom anode and LiF/Ca/Au as the semitransparent top cathode, were fabricated. Nanometers Au/V2O5 layer was deposited on Al anode for holes injection enhancement and the top cathode was capped with additional Alq(3) layer as the dielectric capping layer for increasing its transmittance. Using three emissive layers with red, green, blue phosphorescent emitters respectively, the WOLED showed a maximum external quantum efficiency of 9.1% and a maximum power efficiency of 12.8 lm/W. Broadband emission spectra with a very weak angular dependence were achieved. The emission in normal direction has a Commission Internationale de L'Eclairage coordinates of ( x = 0.36, y = 0.43). The characteristics of this top-emitting WOLED are competitive with those of the corresponding bottom-emitting device.