A dual host system for OLEDs that contains hole-transporting indolocarbazole and electron-transporting indolocarbazole exhibiting superior performance in the OLEDs is disclosed.

The present specification relates to an organic light emitting device, and a composition for forming an organic material layer.

Fluorene derivatives that are connected in one or more of the 1-, 1′-, 4-, or 4′-positions in any combination to a carbon atom of a diaryl substituted triazinyl or pyrimidinyl derivative. The fluorene derivatives are not spirobifluorene derivatives. The compounds are suitable for use in electronic devices, in particular organic electroluminescent devices, comprising these compounds. In some embodiments, the compounds are used as matrix materials for phosphorescent or fluorescent emitters as well as a hole-blocking or an electron-transport layer.

A dual host system for OLEDs that contains hole-transporting indolocarbazole and electron-transporting indolocarbazole exhibiting superior performance in the OLEDs is disclosed.

This invention relates to compounds containing heterocycles or azaheterocycles and phenylene or azaphenylene wherein at least one ring is a five-membered ring. These novel compounds are useful as host materials for phosphorescent electroluminescent devices.

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

##STR00001##

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.

A compound of:

##STR00001##

is disclosed. In Formula IV, ring B and ring C are each independently a 5 or 6-membered carbocyclic or heterocyclic ring; A-B represents a bonded pair of carbocyclic or heterocyclic rings coordinated to a metal M via a nitrogen atom in ring A and an sp.sup.2 hybridized atom in ring B; A-C represents a bonded pair of carbocyclic or heterocyclic rings; M is a metal having an atomic number greater than 40; L is a monoanionic bidentate ligand; m is the oxidation state of the metal M; and n is at least 1.

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

An OLED containing an emissive dopant that is a heteroleptic complex having the formula Ir(L.sub.A-B).sub.2(L.sub.C-D) is disclosed. In the formula, L.sub.A-B is ##STR00001##
and L.sub.C-D can be selected from ##STR00002##