Organic electroluminescent materials and devices

A compound of Formula Ir(LA)x(LB)y(LC)z, wherein:

• x and y are each independently 1 or 2;
• z is 0 or 1;
• x+y+z=3;
• the first ligand LA comprises a structure of Formula I,
• the ligand LB comprises a structure of Formula II,
• the ligand LC is a bidentate ligand;
• each of A1 to A8, X1 to X4, Z1, and Z2 are each independently C or N;
• at least one of X1 to X4 is N;
• Y is selected from the group consisting of BR, BRR′, NR, PR, P(O)R, O, S, Se, C═O, C═S, C═Se, C═NR′, C═CRR′, S═O, SO2, CRR′, SiRR′, and GeRR′;
• moiety C is a monocyclic ring or a polycyclic fused ring system, wherein the monocyclic ring or each ring of the polycyclic fused ring system is independently a 5-membered to 10-membered carbocyclic or heterocyclic ring;
• each of RA, RB, RC, and RD independently represents mono to the maximum allowable substitutions, or no substitutions;
• each R, R′, R1, R2, R3, R4, RA, RB, RC, and RD is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, germyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, selenyl, and combinations thereof;
• and
• any two substituents may be joined or fused to form a ring;
• if X2 is N, then at least one of X1, X3, X4 is N or at least two RB are joined to form a ring or at least one RAis electron withdrawing group, a silyl group, a germyl group, a heteroalkyl group, a cycloalkyl group, a hetrocycloalkyl group, or an alkyl group having three or more carbon atoms;
• if z is 0 and A8 is bonded to ring A, then no RB comprises more than two rings fused together;
• if x is 1 and y is 2, then the following provisos apply:
• (1) if moiety C is pyridine with Z1 is N, ligand LA has a structure of
• and R4 is H, CH3, or CD3, then at least one of R1, R2 or R3 comprises at least two carbon atoms;
• (2) if moiety C is pyridine with Z1 is N, ligand LA has a structure of
• and R4 is H, CH3, or CD3, then R3 is not H, methyl, ethyl, isopropyl, or tert-butyl;
• (3) if X2 and X4 are N, X1 and X3 are C, and A8 is bonded to moiety A, then at least one RA is not hydrogen;
• and
• (4) if X1 is N, and X2, X3, and X4 are C, and two RB are joined to form a fused benzene ring without further fusing, then at least one RA comprises two or more carbon atoms.