Organic electroluminescent materials and devices

1. A compound having a formula:

wherein rings A, B, C, and D each independently represent a 5-membered or 6-membered carbocyclic or heterocyclic ring;

wherein ring E is fused to ring D;

wherein R A , R B , R C , and R D each independently represents mono to a maximum possible number of substitutions, or no substitution;

wherein m1, m2, and m3 are each independently an integer of 0 or 1; when m2 is 0, each of m1 and m3 is 1; when m2 is 1, each of m1 and m3 can be 0 or 1;

wherein when m1 is 0, L 1 is not present; when m2 is 0, L 2 is not present; when m3 is 0, L 3 is not present;

wherein Li, L 2 , and L 3 each independently selected from the group consisting of a direct bond, BR, NR, PR, O, S, Se, C═O, S═O, SO 2 , CRR′, SiRR′, GeRR′, alkyl, cycloalkyl, and combinations thereof,

wherein R A , R B , R C , R D , R E , R, and R′ 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 R A , R B , R C , R D , R E , R, and R′ are optionally joined to form a ring;

wherein X 1 , X 2 , X 3 and X 4 each independently selected from the group consisting of carbon and nitrogen;

wherein Q 1 , Q 2 , Q 3 and Q 4 are each independently selected from the group consisting of direct bond and oxygen;

wherein when any of X 1 , X 2 , X 3 and X 4 is nitrogen, the Q 1 , Q 2 , Q 3 and Q 4 attached thereto is a direct bond; and

wherein M is Pt or Pd.

2. The compound of claim 1 , wherein each Q 1 , Q 2 , Q 3 and Q 4 is a direct bond.

3. The compound of claim 1 , wherein one of Q 1 , Q 2 , Q 3 and Q 4 is oxygen, the remaining three of Q 1 , Q 2 , Q 3 and Q 4 are direct bonds.

4. The compound of claim 1 , wherein two of X 1 , X 2 , X 3 and X 4 are carbon atoms, and the remaining two of X 1 , X 2 , X 3 and X 4 are nitrogen atoms.

5. The compound of claim 1 , wherein three of X 1 , X 2 , X 3 and X 4 are carbon atoms, and the remaining one of X 1 , X 2 , X 3 and X 4 is nitrogen atom.

6. The compound of claim 1 , wherein each X 1 , X 2 , X 3 and X 4 are carbon atoms.

7. The compound of claim 1 , wherein each Li, L 2 , and L 3 is a direct bond.

8. The compound of claim 1 , wherein at least one of Li, L 2 , and L 3 is not a direct bond.

9. The compound of claim 1 , wherein Li and L 3 are direct bond and present, and L 2 is either not a direct bond or not present.

10. The compound of claim 1 , wherein rings A, B, C and D are each independently selected from the group consisting of phenyl, pyridine, imidazole, and imidazole derived carbene.

11. The compound of claim 1 , wherein the compound has at least one Pt-carbene bond.

12. The compound of claim 1 , wherein R E is selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof.

13. The compound of claim 1 , wherein the compound is selected from the group consisting of:

14. The compound of claim 1 , wherein the compound is selected from the group consisting of:

15. The compound of claim 1 , wherein the compound is selected from groups consisting of:

16. 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 formula:

wherein rings A, B, C, and D each independently represents a 5-membered or 6-membered carbocyclic or heterocyclic ring;

wherein ring E is fused to ring D;

wherein R A , R B , R C , and R D each independently represents mono to a maximum possible number of substitutions, or no substitution;

wherein m1, m2 and m3 are each independently an integer of 0 or 1; when m2 is 0, each of m1 and m2 is 1; when m2 is 1, each of m1 and m3 can be 0 or 1;

wherein when m1 is 0, L 1 is not present; when m2 is 0, L 2 is not present; when m3 is 0, L 3 is not present;

wherein Li, L 2 , and L 3 each independently selected from the group consisting of a direct bond, BR, NR, PR, O, S, Se, C═O, S═O, SO 2 , CRR′, SiRR′, GeRR′, alkyl, cycloalkyl, and combinations thereof,

wherein R A , R B , R C , R D , R E , R, and R′ 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 R A , R B , R C , R D , R E , R, and R′ are optionally joined to form a ring;

wherein X 1 , X 2 , X 3 and X 4 each independently selected from the group consisting of carbon and nitrogen;

wherein Q 1 , Q 2 , Q 3 and Q 4 are each independently selected from the group consisting of direct bond and oxygen;

wherein when any of X 1 , X 2 , X 3 and X 4 is nitrogen, the Q 1 , Q 2 , Q 3 and Q 4 attached thereto is a direct bond; and

wherein M is Pt or Pd.

17. The OLED of claim 16 , 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 16 , 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 formula:

wherein rings A, B, C, and D each independently represents a 5-membered or 6-membered carbocyclic or heterocyclic ring;

wherein ring E is fuses to ring D;

wherein R A , R B , R C , and R D each independently represents mono to a maximum possible number of substitutions, or no substitution;

wherein m1, m2 and m3 are each independently an integer of 0 or 1; when m2 is 0, each of m1 and m2 is 1; when m2 is 1, each of m1 and m3 can be 0 or 1;

wherein when m1 is 0, L 1 is not present; when m2 is 0, L 2 is not present; when m3 is 0, L 3 is not present;

wherein Li, L 2 , and L 3 are each independently selected from the group consisting of a direct bond, BR, NR, PR, O, S, Se, C═O, S═O, SO 2 , CRR′, SiRR′, GeRR′, alkyl, cycloalkyl, and combinations thereof,

wherein R A , R B , R C , R D , R E , R, and R′ 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 R A , R B , R C , R D , R E , R, and R′ are optionally joined to form a ring;

wherein X 1 , X 2 , X 3 and X 4 each independently selected from the group consisting of carbon and nitrogen;

wherein Q 1 , Q 2 , Q 3 and Q 4 each independently selected from the group consisting of direct bond and oxygen;

wherein when any of X 1 , X 2 , X 3 and X 4 is nitrogen, the Q 1 , Q 2 , Q 3 and Q 4 attached thereto is a direct bond; and

wherein M is Pt or Pd.

20. The consumer product of claim 19 , wherein the consumer product is one 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 wall comprising multiple displays tiled together, a theater or stadium screen, or a sign.