Patent ID: 6885025

Claim:
An organic light emitting device comprising: an emissive region disposed between and electrically connected to an anode and a cathode, wherein the emissive region comprises: a first emissive layer, comprising a first host material and a first emissive material, and a second emissive layer in physical contact with the first emissive layer and comprising a second host material and a second emissive material, wherein: the contact between the first emissive layer and the second emissive layer provides an electron injection barrier, a hole injection barrier, or both, the first emissive layer is nearer to the anode than the second emissive layer, at least one of the first emissive material or the second emissive material is a phosphorescent emissive material, and wherein the device emits with CIE x,y-coordinates that vary less than about 0.04 over the luminance range of about 1000 cd/m 2 to about 20,000 cd/m 2 .