| abstract |
This disclosure relates, at least in part, an organic light emitting device, which in some embodiments comprises an anode (115); a cathode (160); a first emissive layer (135) disposed between the anode and the cathode, the first emissive layer comprising an electron transporting compound and a phosphorescent emissive dopant compound; and wherein the phosphorescent emissive dopant compound has a concentration gradient, in the emissive layer, which varies from the cathode side of the first emissive layer to the anode side of the emissive layer. |