Patent ID: 7651790

Claim:
An organic light-emitting device, comprising: an emission layer comprising a bipolar phosphorescent host and a phosphorescent dopant interposed between a first electrode and a second electrode, wherein the bipolar phosphorescent host is represented by formula 1: A—C—B (1) where A is a hole transport unit, B is an electron transport unit, and C is a bond or a linking group, wherein the hole transport unit A is where each of R and R′ is selected from a group consisting of H, a C 1 -C 22 alkyl group, an alkoxy group, a CN group, a NO 2 group, and a —O—Ar group where Ar is selected from a group consisting of phenyl, biphenyl, 1-naphthyl, and 2-naphthyl; and X is selected from a group consisting of O, C—(R) 2 , NR, S, and N═N, and wherein the electron transport unit B is selected from the group of a fluorene unit, a spirofluorene unit, and an aluminum hydroquinoline unit represented by