A compound having the formula Ir(L A ) n (L B ) 3-n is disclosed wherein L A is an aza-DBF ligand and L B is an alkyl-substituted phenylpyridine ligand, wherein the compound has a structure according to Formula I: wherein A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 , and A 8 comprise carbon or nitrogen; wherein at least one of A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 , and A 8 is nitrogen; wherein ring B is bonded to ring A through a C-C bond; wherein the iridium is bonded to ring A through a Ir-C bond; wherein X is O, S, or Se; wherein R 1 and R 2 each independently represent mono-, di-, tri-, tetra-substitution, or no substitution; wherein R' and R" each independently represent mono-, di-substitution, or no substitution; wherein any adjacent substitutions in R', R", R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 are optionally linked together to form a ring; wherein R 1 , R 2 , R', and R"are each independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein R 3 , R 4 , R 5 , and R 6 are each independently selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, and combinations thereof; wherein n is an integer from 1 to 3; and wherein total number of carbons in at least one of the pairs R 3 and R 4 , and R 5 and R 6 is at least four.