Patent ID: 8604689

Claim:
An emissive construct comprising: a first emissive layer disposed between a second emissive layer and a third emissive layer; wherein the first emissive layer comprises a host material, the second emissive layer comprises the host material, and the third emissive layer comprises the host material; wherein the host material emits blue light by fluorescence; wherein the first emissive layer comprises at least a first phosphorescent dopant, and the second emissive layer and the third emissive layer are undoped; or the first emissive layer is undoped, the second emissive layer comprises at least a first phosphorescent dopant, and the third emissive layer comprises at least a second phosphorescent dopant; and a triplet energy of the host material is greater than a triplet energy of the first phosphorescent dopant; and at least one of the following relationships exists: a HOMO energy level of the first phosphorescent dopant is higher than a HOMO energy level of the host material; and a LUMO energy level of the first phosphorescent dopant is lower than a LUMO energy level of the host material.