ORGANIC ELECTROLUMINESCENT MATERIALS AND DEVICES

1 .- 20 . (canceled)

21 . A compound selected from formula I or formula II

wherein X 1 to X 8 are independently selected from N or C;

Y 1 to Y 4 are independently selected from the group consisting of O, S, Se, CRR′, and NR;

a, b, c, d, e, f, and g is an integer independently selected from 0 or 1; wherein at least two of a, b, and c are 1; and at least one of d, e, f, and g is 1;

wherein R 1 to R 7 represent monosubstitution, to the maximum allowable substitution, or no substitution;

wherein R, R′, and each of R 1 to R 7 are independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, cyclic amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

wherein any two adjacent substitutions in R, R′, and R 1 to R 7 optionally join to form a ring;

wherein at least one of R, R′, and R 1 to R 7 comprises a group selected from the group consisting of deuterium,

and combinations thereof;

wherein X 9 to X 24 are independently selected from N or CR; and at least one of X 19 to X 24 is N; and

Z is selected from the group consisting of CRR′, NR, N, O, S, and Se.

22 . The compound of claim 21 , wherein R, R′, and R 1 to R 7 is each independently selected from the group consisting of hydrogen, deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, and combinations thereof.

23 . The compound of claim 21 , wherein R, R′, and R 1 to R 7 is each independently selected from the group consisting of hydrogen, deuterium, fluorine, alkyl, cycloalkyl, alkoxy, aryloxy, amino, silyl, aryl, heteroaryl, sulfanyl, and combinations thereof.

24 . The compound of claim 21 , wherein X 1 to X 8 are each C.

25 . The compound of claim 24 , wherein, if present, each of Y 1 to Y 4 is selected from NR, O, or S.

26 . The compound of claim 21 , wherein one or two of a, b, and c is 0, or one or two of d, e, f, and g is 0.

27 . The compound of claim 5 , wherein one or two of a, b, and c is 0, or one or two of d, e, f, and g is 0.

28 . The compound of claim 21 , wherein the compound is selected from the group consisting of:

29 . The compound of claim 21 , wherein Y 1 , Y 2 , Y 3 , and Y 4 are the same.

30 . The compound of claim 21 , wherein at least one of the adjacent R 1 , R 2 , and R 3 joins to form a ring.

31 . The compound of claim 21 , wherein, if present, Y 1 , Y 2 , Y 3 , and Y 4 are S.

32 . The compound of claim 21 , wherein, if present, Y 1 , Y 2 , Y 3 , and Y 4 are O.

33 . The compound of claim 21 , wherein, if present, Y 1 , Y 2 , Y 3 , and Y 4 are NR.

34 . The compound of claim 21 , wherein at least one of R, R′, and_R 1 to R 7 is selected from the group consisting of:

and any combination thereof;

wherein Y, Y′, and Y″ is independently selected from the group consisting of O, S, Se, C(CH 3 ) 2 and N-Ph; and

wherein Z 1 to Z 12 are independently selected from CH or N.

35 . The compound of claim 21 , wherein the compound is selected from the group consisting of:

36 . An organic light emitting device (OLED) comprising:

an anode; a cathode; and an organic layer disposed between the anode and the cathode, the organic layer comprising a compound selected from Formula I or Formula II

wherein X 1 to X 8 are independently selected from N or C;

Y 1 to Y 4 are independently selected from the group consisting of O, S, Se, CRR′, and NR;

a, b, c, d, e, f, and g is an integer independently selected from 0 or 1; wherein at least two of a, b, and c are 1; and at least one of d, e, f, and g is 1;

wherein R 1 to R 7 represent monosubstitution, to the maximum allowable substitution, or no substitution;

wherein R, R′, and each of R 1 to R 7 are independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, cyclic amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

wherein any two adjacent substitutions in R, R′, and R 1 to R 7 optionally join to form a ring;

wherein at least one of R, R′, and R 1 to R 7 comprises a group selected from the group consisting of deuterium,

and combinations thereof;

wherein X 9 to X 24 are independently selected from N or CR; and at least one of X 19 to X 24 is N; and

Z is selected from the group consisting of CRR′, NR, N, O, S, and Se.

37 . The OLED of claim 36 , wherein the organic layer further comprises a phosphorescent emissive dopant;

wherein the emissive dopant is a transition metal complex having at least one ligand or part of the ligand if the ligand is more than bidentate selected from the group consisting of:

wherein each Y 1 to Y 13 are independently selected from the group consisting of carbon and nitrogen;

wherein Y′ is selected from the group consisting of BR e , NR e , PR e , O, S, Se, C═O, S═O, SO 2 , CR e R f , SiR e R f , and G e R e R f ;

wherein R e and R f are optionally fused or joined to form a ring;

wherein each R a , R b , R c , and R d may independently represent from mono substitution to the maximum possible number of substitution, or no substitution;

wherein each R a , R b , R c , R d , R e , and R f is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and

wherein any two adjacent substituents of R a , R b , R c , and R d are optionally fused or joined to form a ring or form a multidentate ligand.

38 . 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, the organic layer comprising a compound selected from Formula I or Formula II

wherein X 1 to X 8 are independently selected from N or C;

Y 1 to Y 4 are independently selected from the group consisting of O, S, Se, CRR′, and NR;

a, b, c, d, e, f, and g is an integer independently selected from 0 or 1; wherein at least two of a, b, and c are 1; and at least one of d, e, f, and g is 1;

wherein R 1 to R 7 represent monosubstitution, to the maximum allowable substitution, or no substitution;

wherein R, R′, and each of R 1 to R 7 are independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, cyclic amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

wherein any two adjacent substitutions in R, R′, and R 1 to R 7 optionally join to form a ring;

wherein at least one of R, R′, and R 1 to R 7 comprises a group selected from the group consisting of deuterium,

and combinations thereof;

wherein X 9 to X 24 are independently selected from N or CR; and at least one of X 19 to X 24 is N; and

Z is selected from the group consisting of CRR′, NR, N, O, S, and Se.

39 . The consumer product of claim 38 , wherein the consumer product is selected from the group consisting of a flat panel display, a curved display, a computer monitor, a medical monitor, a television, a billboard, a light for interior or exterior illumination and/or signaling, a heads-up display, a fully or partially transparent display, a flexible display, a rollable display, a foldable display, a stretchable display, a laser printer, a telephone, a cell phone, tablet, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a camcorder, a viewfinder, a micro-display that is less than 2 inches diagonal, a 3-D display, a virtual reality or augmented reality display, a vehicle, a video walls comprising multiple displays tiled together, a theater or stadium screen, and a sign.

40 . A formulation comprising a compound according to claim 21 .