A phosphorescent emitter or delayed fluorescent and phosphorescent emitters represented by Formula I or Formula II, where M is platinum or palladium. ##STR00001##

Provided are organometallic compounds comprising a ligand which comprises a first moiety A which is a heterocyclic ring comprising at least 7 ring atoms selected from the group consisting of C, Si, B, O, S, and N, and a second moiety B which is a 5-membered or 6-membered carbocyclic or heterocyclic ring. Also provided are formulations comprising these organometallic compounds. Further provided are organic light emitting devices (OLEDs) and related consumer products that utilize these organometallic compounds.

The present invention provides an organic light emitting device comprising at least one light emitting layer which comprises a first host compound and a second host compound, and the organic light emitting device has improved driving voltage, efficiency and lifetime.

Compounds comprising phosphorescent metal complexes comprising cyclometallated imidazo[1,2-f]phenanthridine and diimidazo[1,2-a:1,2-c]quinazoline ligands, or isoelectronic or benzannulated analogs thereof, are described. Organic light emitting diode devices comprising these compounds are also described.

The present specification relates to a hetero-cyclic compound and an organic light emitting device comprising the same.

Compounds comprising phosphorescent metal complexes comprising cyclometallated imidazo[1,2-f]phenanthridine and diimidazo[1,2-a:1,2-c]quinazoline ligands, or isoelectronic or benzannulated analogs thereof, are described. Organic light emitting diode devices comprising these compounds are also described.

Provided is a novel compound of Chemical Formula 1:

##STR00001##

wherein Ar.sub.1 and Ar.sub.2 are each independently a substituted or unsubstituted C.sub.6-15 aryl, R.sub.1 and R.sub.2 are each independently hydrogen or deuterium, n1 is an integer of 1 to 7, and n2 is an integer of 1 to 6. Also provided is an organic light-emitting device including the compound. When a compound of Chemical Formula 1 is used as a material for hole injection, hole transport, light emission, or electron transport and injection of an organic electroluminescent device, a device having low voltage, high efficiency, and long lifetime characteristics can be obtained.

Disclosed is a benzazole derivative having a heteroaryl group, wherein the benzazole derivative having the heteroaryl group is represented by Chemical Formula 1. Also disclosed is an organic electroluminescence device including an organic layer containing the benzazole derivative having the heteroaryl group: ##STR00001## wherein, each of Z1, X1, X2, X3, Ar1, Ar2, Ar3, m1, m2 and q is the same as defined in the specification.

Compounds comprising phosphorescent metal complexes comprising cyclometallated imidazo[1,2-f]phenanthridine and diimidazo[1,2-a:1,2-c]quinazoline ligands, or isoelectronic or benzannulated analogs thereof, are described. Organic light emitting diode devices comprising these compounds are also described.

Arrangements for phosphorescent blue emissive materials, layers, and devices are provided. The arrangements include a host having first a triplet energy level of at least 2.8 eV and an absolute difference of not more than 0.3 eV between the first singlet and triplet energy levels, and an emitter that includes an emissive transition metal complex and a first triplet energy level of at least 2.7 eV.