Organic electroluminescent materials and devices

1. A compound comprising a first ligand L A having Formula I:

wherein ring B is a 5 or 6-membered carbocyclic or heterocyclic ring;

wherein R B represents mono to the possible maximum number of substitution, or no substitution;

wherein Z 1 and Z 2 are each independently selected from the group consisting of carbon or nitrogen;

wherein A 1 , A 2 , A 3 , and A 4 are each independently CR or N;

wherein ring C is a 5 or 6-membered aromatic ring;

n is 0 or 1;

wherein when n is 0, A 8 is not present, and A 5 , A 6 , and A 7 are each independently selected from the group consisting of CR, NR′, O, S, and Se;

wherein when n is 1, A 5 , A 6 , A 7 , and A 8 are each independently CR or N, and at least two adjacent A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 , and A 8 are CR and the Rs are joined together to form a six-membered ring fused to ring A or ring C;

wherein, if (i) n=0, (ii) at least two adjacent A 5 , A 6 , and A 7 , are CR and the Rs are joined together to form a six-membered ring fused to ring C, and (iii) ring B is imidazole, then Z 1 is carbene carbon;

wherein each R and R′ in CR or NR′ can be the same or different;

wherein X is O, S, or Se;

wherein R, R′ and R B are each 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;

wherein any adjacent substituents are optionally joined or fused into a ring;

wherein the ligand L A is coordinated to a metal M;

wherein the metal M is bonded to ring A through a M-C bond;

wherein the metal M can be coordinated to other ligands; and

wherein the ligand L A is optionally linked with other ligands to comprise a tridentate, tetradentate, pentadentate or hexadentate ligand.

2. The compound of claim 1 , wherein M is selected from the group consisting of Ir, Rh, Re, Ru, Os, Pt, Au, and Cu.

3. The compound of claim 1 , wherein X is O.

4. The compound of claim 1 , wherein n is 1, and each A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 , and A 8 is independently a CR.

5. The compound of claim 1 , wherein n is 1, and at least one of A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 , and A 8 is N.

6. The compound of claim 1 , wherein n is 1, and at least two adjacent A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 , and A 8 are CR and the Rs are joined together to form a phenyl ring fused to ring A or ring C.

7. The compound of claim 1 , wherein the ligand L A is selected from the group consisting of:

wherein Y is selected from the group consisting of O, S, Se, and NR′; and

wherein R A and R C have the same definition as R B .

8. The compound of claim 1 , wherein the compound has the formula of M(L A ) x (L B ) y (L C ) z ;

wherein L B is a second ligand, and L C is a third ligand, and L B and L C can be the same or different;

wherein x is 1, 2, or 3;

wherein y is 0, 1, or 2;

wherein z is 0, 1, or 2;

wherein x+y+z is the oxidation state of the metal M;

wherein the second ligand L B and the third ligand L c are each independently selected from the group consisting of:

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

wherein X is selected from the group consisting of BR′, NR′, PR′, O, S, Se, C═O, S═O, SO 2 , CR′R″, SiR′R″, and GeR′R″;

wherein R′ and R″ are optionally fused or joined to form a ring;

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

wherein R′, R″, R a , R b , R c , and R d are each 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.

9. The compound of claim 8 , wherein the ligand L A is selected from the group consisting of:

10. The compound of claim 9 , wherein the compound is the Compound A-x having the formula Ir(L Ai )(L Bj ) 2 ;

wherein x=300i+j−300; i is an integer from 1 to 860, and j is an integer from 1 to 300; and

wherein the ligand L B is selected from the group consisting of:

11. The compound of claim 8 , wherein the compound has the formula of Ir(L A ) n (L B ) 3-n or Ir(L A )(L B )(L C ); wherein n is 1, 2, or 3.

12. The compound of claim 8 , wherein the ligand L B is selected from the group consisting of:

13. The compound of claim 8 , wherein the compound has formula of Ir(L A ) 2 (L c );

wherein the ligand L c is selected from the group consisting of:

14. A formulation comprising a compound of claim 1 .

15. 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 L A having Formula I:

wherein ring B is a 5 or 6-membered carbocyclic or heterocyclic ring;

wherein R B represents mono to the possible maximum number of substitution, or no substitution;

wherein Z 1 and Z 2 are each independently selected from the group consisting of carbon or nitrogen;

wherein A 1 , A 2 , A 3 , and A 4 are each independently CR or N;

wherein ring C is a 5 or 6-membered aromatic ring;

n is 0 or 1;

wherein when n is 0, A 8 is not present, and A 5 , A 6 , and A 7 are each independently selected from the group consisting of CR, NR′, O, S, and Se;

wherein when n is 1, A 5 , A 6 , A 7 , and A 8 are each independently a CR or N, and at least two adjacent A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 , and A 8 are CR and the Rs are joined together to form a six-membered ring fused to ring A or ring C;

wherein, if (i) n=0, (ii) at least two adjacent A 5 , A 6 , and A 7 , are CR and the Rs are joined together to form a six-membered ring fused to ring C, and (iii) ring B is imidazole, then Z 1 is carbene carbon;

wherein each R and R′ in CR or NR′ can be the same or different;

wherein X is O, S, or Se;

wherein R, R′ and R B are each 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;

wherein any adjacent substituents are optionally joined or fused into a ring;

wherein the ligand L A is coordinated to a metal M;

wherein the metal M is bonded to ring A through a M-C bond;

wherein the metal M can be coordinated to other ligands; and

wherein the ligand L A is optionally linked with other ligands to comprise a tridentate, tetradentate, pentadentate or hexadentate ligand.

16. The OLED of claim 15 , wherein the organic layer is an emissive layer and the compound is an emissive dopant or a non-emissive dopant.

17. The OLED of claim 15 , wherein the organic layer further comprises a host, wherein host comprises at least one chemical group selected from the group consisting of triphenylene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, azatriphenylene, azacarbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene.

18. The OLED of claim 15 , wherein the organic layer further comprises a host, wherein the host is selected from the group consisting of:

and combinations thereof.

19. 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 having a ligand of Formula I:

wherein ring B is a 5 or 6-membered carbocyclic or heterocyclic ring;

wherein R B represents mono to the possible maximum number of substitution, or no substitution;

wherein Z 1 and Z 2 are each independently selected from the group consisting of carbon or nitrogen;

wherein A 1 , A 2 , A 3 , and A 4 are each independently CR or N;

wherein ring C is a 5 or 6-membered aromatic ring;

n is 0 or 1;

wherein when n is 0, A 8 is not present, and A 5 , A 6 , and A 7 are each independently selected from the group consisting of CR, NR′, O, S, and Se;

wherein when n is 1, A 5 , A 6 , A 7 , and A 8 are each independently CR or N, and at least two adjacent A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 , and A 8 are CR and the Rs are joined together to form a six-membered ring fused to ring A or ring C;

wherein, if (i) n=0, (ii) at least two adjacent A 5 , A 6 , and A 7 , are CR and the Rs are joined together to form a six-membered ring fused to ring C, and (iii) ring B is imidazole, then Z 1 is carbene carbon;

wherein each R and R′ in CR or NR′ can be the same or different;

wherein X is O, S, or Se;

wherein R, R′ and R B are each 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;

wherein any adjacent substituents are optionally joined or fused into a ring;

wherein the ligand L A is coordinated to a metal M;

wherein the metal M is bonded to ring A through a M-C bond;

wherein the metal M can be coordinated to other ligands; and

wherein the ligand L A is optionally linked with other ligands to comprise a tridentate, tetradentate, pentadentate or hexadentate ligand.

20. The consumer product of claim 19 , wherein the consumer product is one of a flat panel display, a computer monitor, a medical monitors 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 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 wall comprising multiple displays tiled together, a theater or stadium screen, and a sign.