A compound comprising a first ligand L.sub.A of Formula I,

##STR00001##

is provided. In Formula I, ring A is a 5-membered or 6-membered ring; K is a direct bond, O, or S; X.sup.1 to X.sup.8 are independently C or N; Y is a linker that forms a 5-membered ring between rings B and C; Z.sup.1 and Z.sup.2 are C or N; each R, R, R, R.sup.A, R.sup.B, R.sup.C, and R.sup.1 is a hydrogen or a General Substituent; L.sub.A is coordinated to a metal M by the dashed lines; and (i) at least one R.sup.C is a cyclic group that is not fused to ring C, or (ii) ring A has a structure of Formula II,

##STR00002##

and ring A is bonded to ring B at X.sup.1; or (iii) both (i) and (ii). Formulations, OLEDs, and consumer products containing the compound are also provided.

Compounds comprising phosphorescent metal complexes comprising cyclometallated ligands having a structure of

##STR00001##

In the vgs3, each of the E.sup.1 atoms is selected from C and N, except that E.sup.1g is selected from C, N, and S. The E.sup.1 atoms collectively comprise an 18 pi-electron system, provided that E.sup.1a and E.sup.1p are different. The R.sup.1 substituents are each, independently, H, hydrocarbyl, heteroatom substituted hydrocarbyl, cyano, fluoro, OR.sup.2a, SR.sup.2a, NR.sup.2aR.sup.2b, BR.sup.2aR.sup.2b, or SiR.sup.2aR.sup.2bR.sup.2c, where the R.sup.2 substituents are each, independently, hydrocarbyl or heteroatom substituted hydrocarbyl. Any of the R.sup.1 or R.sup.2 substituents can be linked to form a saturated or unsaturated, aromatic or non-aromatic ring, provided that the R.sup.1 substituents are not present when the corresponding one of E atoms is N or S. Organic light emitting diode devices comprising these compounds are also described.

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.

An organometallic compound and an organic light-emitting device including the same are disclosed. The organometallic compound includes a transition metal and at least one organic ligand, wherein the organometallic compound satisfies predetermined conditions described in the specification.

Disclosed is a class of dendrimers containing cyclometalated tridentate platinum(II) compounds with one monoanionic auxiliary ligand, both coordinated to a platinum (II) metal center and having the chemical structure shown in generic formula (I), wherein at least one of R.sub.1, R.sub.2 and R.sub.3 being a dendrimeric moiety of general formula (II), each being optionally substituted.

##STR00001##

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.

A compound comprising a ligand L.sub.A coordinated to a metal M

##STR00001## wherein ring A, ring T, and ring W are independently selected from a 5-membered or 6-membered heterocyclic or carbocyclic ring, and the ring W is fused to the ring T. The metal compounds having a ligand L.sub.A can be found in an OLED that includes an organic layer positioned between an anode and a cathode where the organic layer comprises a metal compound above having a ligand L.sub.A disclosed herein. We also describe a consumer product comprising the OLED.

The present invention relates to nitrogen-containing heteroaromatics suitable for use in electronic devices, and to electronic devices, especially organic electroluminescent devices, comprising these compounds.

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.