A light-emitting device having a fused cyclic compound includes: a first electrode; a second electrode facing the first electrode; an interlayer between the first electrode and the second electrode and including an emission layer; and a fused cyclic compound of Formula 1:

##STR00001## wherein, in Formula 1, the variables are as defined herein.

A compound comprising a first ligand L.sub.A having the formula ##STR00001##
Formula I, is disclosed. In Formula I, ring A is a five- or six-membered carbocyclic or heterocyclic ring; Y.sup.1 is selected from carbon and nitrogen; each of X.sup.1 to X.sup.4 is C or N; at least two adjacent R.sup.2s of ring B form a fused structure having the following formula: ##STR00002##
ring C is fused to ring B and the wavy lines are bonds attached to ring B; ring D and ring E are either a 5-membered aromatic ring or a 6-membered aromatic ring; each R.sup.1, R.sup.2, R.sup.3, R.sup.A, R.sup.B, R.sup.C, and R.sup.D is independently selected from a variety of substituents; ligand L.sub.A is coordinated to a metal M and, optionally, linked with other ligands; and M is optionally coordinated to other ligands. Organic light emitting devices and consumer products containing the compounds are also disclosed.

An organometallic compound represented by Formula 1:
M(L.sub.1).sub.n1(L.sub.2).sub.n2(L.sub.3).sub.n3  Formula 1 wherein in Formula 1, M, L.sub.1, L.sub.2, L.sub.3, n1, n2, and n3 are the same as defined in the specification.

A compound having a first ligand L.sub.A of Formula I ##STR00001##
is disclosed, where Z.sup.1 to Z.sup.4 are each independently C or N; at least one of Z.sup.1 to Z.sup.4 is N; and ring A is a structure of Formula II ##STR00002##

A phosphorescent compound of formula (I): ##STR00001##
wherein: M is a transition metal; C.sup.1 is a carbon atom forming a metal-carbene bond with M; A is a saturated bridged bicyclic or saturated bridged tricyclic group consisting of one nitrogen atom and 6-12 carbon atoms; either: (i) X.sup.1 is a bridgehead carbon atom of the bridged bicyclic or bridged tricyclic group and X.sup.2 is NR.sup.1 wherein R.sup.1 is a substituent, or (ii) X.sup.1 is N and X.sup.2 is a bridgehead group of formula CR.sup.6 wherein R.sup.6 is H or a substituent; Ar.sup.1 is a C.sub.6-20 aromatic group or a 5-20 membered heteroaromatic group; L in each occurrence is independently a mono- or poly-dentate ligand other than a ligand of formula A-Ar.sup.1; x is at least 1; and y is 0 or a positive integer. The compound of formula (I) may be used as a blue light-emitting material in a white organic light-emitting device.

Provided are organometallic compounds having a ligand L.sub.A of Formula I:

##STR00001##

Also provided are formulations including these organometallic compounds. Further provided are OLEDs and related consumer products that utilize these organometallic compounds.

The present invention relates to an organic electroluminescent device comprising a light-emitting layer comprising an electron-transporting host material and a hole-transporting host material, and to a formulation comprising a mixture of the host materials and to a mixture comprising the host materials. The electron-transporting host material corresponds to a compound of the formula (1) comprising diazadibenzofuran or diazadibenzothiophene units. The hole-transporting host material corresponds to a compound of the formula (2) from the class of the biscarbazoles or the derivatives thereof.

A novel compound having the formula Os(L).sub.n is disclosed, wherein Os is osmium(IV) metal, L is a ligand coordinating to the Os atom, and n is an integer from 1 to 6, wherein each L can be same or different, wherein at least one L is a multidentate ligand, and wherein the compound is neutral.

An organic electroluminescent device includes a first electrode, a hole transport region provided on the first electrode, an emission layer provided on the hole transport region, an electron transport region provided on the emission layer, and a second electrode provided on the electron transport region, wherein the emission layer includes an organometallic compound represented by Formula 1. ##STR00001##

A compound comprising a first ligand L.sub.A of Formula I, ##STR00001##
is disclosed. In the structure of Formula I, ring A is a 5-membered or 6-membered carbocyclic or heterocyclic ring; Z.sup.1-Z.sup.4 are each independently C or N; at least two consecutive Z.sup.1-Z.sup.4 are C, and are fused to a structure of ##STR00002##
or ##STR00003##
Y.sup.1 and Y.sup.2 are each independently O, S, Se, CRR′, SiRR′, or GeRR′; each R.sup.A, R.sup.B, R.sup.C, R, and R′ is a hydrogen or a substituent; and any two substituents may be joined or fused together to form a ring. In the compound, L.sub.A is complexed to a metal M by the dashed lines in Formula I to form a five-membered chelate ring, and M has an atomic weight greater than 40. Organic light emitting devices and consumer products containing the compounds are also disclosed.