Compounds including a ligand L according to Formula I devices containing the same and formulations including the same are described. In Formula I, B is a 5 or 6-membered carbocyclic or heterocyclic ring; C is a condensed aromatic ring system having at least two carbocyclic or heterocyclic rings; 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 sp2 hybridized atom X6 in ring B; RA, RB and RC can represent no substitutions or the maximum substitutions available on the respective ring; X1, X2, X3, X4, X5, and X6 are carbon or nd nitrogen, and X7 is carbon; at least one of RA and RC substituents adjacent to the bond between A and C is not hydrogen; and the ligand is coordinated to a metal, having an atomic number greater than 40.