Universal Display Corporation
ORGANIC ELECTROLUMINESCENT MATERIALS AND DEVICES

Abstract:

Provided is a compound comprising a ligand L.sub.A having ##STR00001## where ring A is a 5-membered or 6-membered cathocyclic or heterocyclic ring; one of X.sup.1-X.sup.4 is C if linked to ring A; one of X.sup.1-X.sup.4 is N if adjacent to the linking C and coordinates to a metal M to form a five-membered chelate ring as indicated by the two dashed lines.