Long lifetime phosphorescent organic light emitting device (OLED) structures

An organic light emitting device, comprising:

• an anode;
• a cathode;
• an emissive layer disposed between the anode and the cathode, the emissive layer further comprising:
• a first organic layer comprising a first phosphorescent material and a first nonemissive material, wherein
• the concentration of the first phosphorescent material in the first organic layer is 10-90 wt %;
• and
• the concentration of the first non-emissive material in the first organic layer is 10-90 wt %;
• a second organic layer comprising a second phosphorescent material and
• a second non-emissive material, wherein
• the concentration of the second phosphorescent material in the second layer is 3-25 wt %;
• and
• the concentration of the second non-emissive material in the second organic layer is 75-97 wt %;
• wherein the concentration of the second phosphorescent material in the second organic layer is lower than the concentration of the first phosphorescent material in the first organic layer;
• wherein the first non-emissive material and the second non-emissive material may be the same material or different materials, and the first phosphorescent material and the second phosphorescent material may be the same material or different materials;
• wherein all organic layers between the first organic layer and the anode do not include any materials containing a group selected from the group consisting of triarylamine, napthyl, tri(N-carbazoyl)triphenylamine, tetraarylamine and carbazole;
• a third organic layer disposed between the first organic layer and the anode;
• and
• wherein the first phosphorescent material and the second phosphorescent material are the same material, and the first non-emissive material and the second non-emissive material are the same material.