Saturated and efficient blue phosphorescent organic light emitting devices with Lambertian angular emission

The authors employ a microcavity to optimize the color of a phosphorescent organic light emitting device (OLED) based on the-sky blue phosphor FIrpic. The output of the OLED is filtered by scattering media to correct the angular emission intensity profile and eliminate the angular dependence of the color. With a holographic diffuser as the scattering medium, the microcavity OLED achieves an external quantum efficiency of (5.5 +/- 0.6)%, as compared to (3.8 +/- 0.4)% for a conventional structure. The color coordinates of the microcavity OLED with holographic diffuser are (x,y)=(0.116 +/- 0.004,0.136 +/- 0.010) with minimal angular color shift and a nearly ideal Lambertian angular emission profile. (c) 2007 American Institute of Physics.