Universal Display Corporation
ORGANIC ELECTROLUMINESCENT MATERIALS AND DEVICES

Abstract:

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##