A compound comprising a heteroleptic iridium complex having the formula: or wherein X is selected from the group consisting of NR, O, S, BR, and Se; wherein R is selected from hydrogen and alkyl; wherein R 1 , R 2 , R 3 , and R 4 may represent mono, di, tri, or tetra substitutions; and wherein each of R 1 , R 2 , R 3 , and R 4 are independently selected from the group consisting of hydrogen, alkyl, and aryl.