Universal Display Corporation
ORGANIC ELECTROLUMINESCENT MATERIALS AND DEVICES

Abstract:

A compound including a bidentate ligand L.sub.A that includes a moiety of Formula I, ##STR00001## is described. In Formula I, ligand L.sub.A is coordinated to a metal M by two bonds, and (i) both bonds are with Formula I, and if the metal M is coordinated by a direct bond to a nitrogen of ring C or ring D, then at least one of ring A, ring B, ring C, and ring D is not a benzene ring; or (ii) one of the two bonds is with Formula I, and the other bond is with Formula II ##STR00002## which is attached to one of rings A, B, C, or D. In addition, each of ring A, ring B, ring C, ring D, and, if present, ring E is a 5-membered or 6-membered ring; each R.sup.A, R.sup.B, R.sup.C, R.sup.D, and R.sup.E is a hydrogen or one of a variety of substituents.