Organic electroluminescent materials and devices

A consumer product comprising an organic light-emitting device (OLED) comprising:

• an anode;
• a cathode;
• and
• an organic layer, disposed between the anode and the cathode, comprising a compound comprising a first ligand LA of Formula I
• wherein,
• ring A and ring B are each independently a 5-membered or 6-membered carbocyclic or heterocyclic ring;
• Z1 to Z5 are each independently C or N;
• two adjacent Z1 to Z4 are not N;
• the Z1 to Z4 that connects to ring B is C;
• at least one of the following is true:
• (a) two of Z1 to Z4 are N;
• or (b) ring A is a 5-membered or 6-membered heterocyclic ring;
• RA, RB, and RC each represents mono to the maximum possible number of substitutions, or no substitution;
• two adjacent RA substituents form a first group fused to ring A;
• wherein the first group is selected from the group consisting of:
• wherein the asterisks in each structure indicate adjacent C atoms that are on ring A;
• each R, RA, RB, and RC is independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, boryl, and combinations thereof;
• the ligand LA is complexed to a metal M to form a 5-membered chelate ring;
• the metal M can be coordinated to other ligands;
• the ligand LA can be linked with other ligands to comprise a tridentate, tetradentate, pentadentate, or hexadentate ligand;
• and
• any two substituents can join or fuse together to form a ring, wherein at least one of the following is true:
• (1) the one of Z1 to Z4 coordinated to metal M is C;
• (2) Z5 is N;
• (3) or ring A is a 5-membered ring.