Patent ID: 7767316

Claim:
An organic light emitting device containing a cathode, an anode, and having located there-between a light emitting layer, comprising: A) co-hosts including a) a hole transporting compound, and b) an aluminum chelate according to the following formula wherein: R 2 represents an electron donating group, R 3 and R 4 each independently represent hydrogen or an electron donating group, R 5 , R 6 , and R 7 each independently represent hydrogen or an electron accepting group, and R 8 , R 9 , R 10 , R 11 , and R 12 collectively contain 18 or fewer carbon atoms and each independently represent hydrogen or substituent groups containing from 1 to 12 carbon atoms, with the proviso that R 8 and R 9 may join together to form a fused ring and with the proviso that R 9 and R 10 may join to form a fused ring; and B) at least one light emitting Iridium compound, wherein the Iridium compound is a tris C^N-cyclometallated complex; and wherein the triplet energies of the hole transporting and aluminum chelate co-host materials are each at least about 0.1 eV greater than that of the tris C^N-cyclometallated iridium complex.