Materials and structures for enhancing the performance of organic light emitting devices

A device, comprising:

• an anode;
• a cathode;
• a first organic layer disposed between the anode and the cathode, wherein the first organic layer comprises a hole transporting material and a material that produces phosphorescent emission when a voltage is applied between the anode and the cathode;
• a second organic layer disposed between the first organic layer and the cathode, wherein the second organic layer is in direct contact with the first organic layer, and wherein the second organic layer comprises an aromatic hydrocarbon material having a highest occupied molecular orbital that is at least 0.81 eV less than the highest occupied molecular orbital of a hole transporting material in the first organic layer, wherein the aromatic hydrocarbon material has the structure
• wherein:
• R1–R5 each represent no substitution, mono-, di-, or tri-substitution, and wherein the substituents are the same or different, and each is selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, heteroalkyl and substituted aryl.

A device, comprising:

• an anode;
• a cathode;
• a first organic layer disposed between the anode and the cathode, wherein the first organic layer comprises a material that produces phosphorescent emission when a voltage is applied between the anode and the cathode;
• a second organic layer disposed between the first organic layer and the cathode, wherein the second organic layer is in direct contact with the first organic layer, and wherein the second organic layer comprises an aromatic hydrocarbon material, and wherein the device has an unmodified external quantum efficiency of at least about 3% and a lifetime of at least about 1000 hours at an initial luminance of about 100 to about 1000 cd/m2, wherein the aromatic hydrocarbon material has the structure
• wherein:
• R1–R5 each represent no substitution, mono-, di-, or tri-substitution, and wherein the substituents are the same or different, and each is selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, heteroalkyl and substituted aryl.