wherein,

two adjacent X¹ to X⁴ are C, at least one of the remaining X¹ to X⁴ is N, and the other of the remaining X¹ to X⁴ is N or CR;

ring A is a 5-membered or 6-membered carbocyclic or heterocyclic ring;

the two adjacent X¹ to X⁴ that are C are fused to a cyclic ring structure selected from the group consisting of

the asterisks indicate the two adjacent X¹ to X⁴ that are C;

Y is O or S;

Z¹ to Z¹⁶ are each independently C or N;

R_A and R_CC each independently represents zero, mono, or up to a maximum allowed number of substitutions to its associated ring;

each of R, R_A, and R_CC is independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

R_B represents two or up to a maximum allowed number of substitutions to its associated ring wherein at least two substituents of R_B are selected from the group consisting of fluorine, an alkyl containing one or more fluorine, cycloalkyl containing one or more fluorine, fully fluorinated alkyl, and fully fluorinated cycloalkyl, and combinations thereof and the remaining R_B are independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

R_C represents one or up to a maximum allowed number of substitutions to its associated ring wherein at least one substituent of R_C is selected from the group consisting of fluorine, an alkyl containing one or more fluorine, cycloalkyl containing one or more fluorine, fully fluorinated alkyl, and fully fluorinated cycloalkyl, and combinations thereof and the remaining R_C are independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

R_D represents one or up to a maximum allowed number of substitutions to its associated ring wherein at least one substituent of R_D is selected from the group consisting of fluorine, an alkyl containing one or more fluorine, cycloalkyl containing one or more fluorine, fully fluorinated alkyl, and fully fluorinated cycloalkyl, and combinations thereof and the remaining R_D are independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

Formula III-B is fused to Formula I only through X¹ and X² together with X⁴ being N and with X³ being CR, wherein R is an alkyl, cycloalkyl, or silyl;

the ligand L_A is coordinated to a metal M through the two indicated dash lines;

the metal M can be coordinated to other ligands;

the ligand L_A can be linked with other ligands to form a tridentate, tetradentate, pentadentate, or hexadentate ligand; and

any two substituents can be joined or fused to form a ring.