A compound having a formula M(LA)x(LB)y(LC)z, where ligand LA is ligand LB is and ligand LC is is disclosed. In formula M(LA)x(LB)y(LC)z, M is a metal having an atomic number greater than 40; x is 1 or 2; A1-A8 are carbon or nitrogen; ring B is bonded to ring A through a C—C bond; M is bonded to ring A through a M-C bond; X is O, S, Se, CRR′, or NR1; rings C and D are each independently a 5 or 6-membered carbocyclic or heterocyclic ring; at least one R4 is a five-membered or six-membered heterocyclic ring which can be further substituted by RE; each R substituent is independently selected from a variety of moieties; and any adjacent R substitutents are optionally joined to form a ring. Formulations and devices, such as an OLEDs, that include the compound of formula M(LA)(LB)(LC)z are also described.