Organic electroluminescent materials and devices

1. A compound of Formula I

wherein A is a fused ring system comprising a six-membered ring, which is fused to a five-membered ring, wherein the five-membered ring is fused to a second five-membered ring and the second five-membered ring is not a pyrazole ring;

wherein B is a five-membered or six-membered carbocyclic or heterocyclic ring;

wherein A and B are connected by a single bond between a carbon atom of A and an atom of B;

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

wherein each R A and R B 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;

wherein M is a metal having an atomic weight greater than 40;

wherein A is coordinated to M by a non-carbene dative bond;

wherein B is coordinated to M by a polar covalent bond between a carbon atom and M;

wherein M is bonded to one of the five-membered rings of A;

wherein L is a substituted or unsubstituted cyclometalated ligand, and each L can be the same or different; and

wherein m is at least 1, and m+n is the maximum number of ligands that may be attached to M.

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

3. The compound of claim 1 , wherein B is a six-membered aromatic ring.

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

5. The compound of claim 1 , wherein M is Ir or Pt.

6. The compound of claim 1 , wherein B is benzene.

7. The compound of claim 1 , wherein the M-A fused ring system is selected from the group consisting of:

wherein C is a six-membered aromatic ring;

wherein R 1 represent mono to the maximum possible number of substitution, or no substitution;

wherein each X is independently selected from the group consisting of O, S, Se, NR, CRR′, SiRR′, BR, and PR;

wherein R 1 , 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 acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

wherein any adjacent substituents in R 1 , R, and R′ are optionally joined or fused to form a ring; and

wherein the dashed line represents the bond to ring B.

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

9. The compound of claim 7 , wherein ring C comprises at least five carbons.

10. The compound of claim 1 , wherein the compound comprises a structure selected from the group consisting of:

11. The compound of claim 1 , wherein each L is independently 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 B R e , N R e , P R e , O, S, Se, C=O, S=O, SO 2 , CR e R f RR, SiR e R f , and GeR 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 acid, 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.

12. The compound of claim 1 , wherein each L is independently selected from the group consisting of:

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

14. A formulation comprising a compound according to 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 having Formula I

wherein A is a fused ring system comprising a six-membered ring, which is fused to a five-membered ring, wherein the five-membered ring is fused to a second five-membered ring and the second five-membered ring is not a pyrazole ring;

wherein B is a five-membered or six-membered carbocyclic or heterocyclic ring;

wherein A and B are connected by a single bond between a carbon atom of A and an atom of B;

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

wherein each R A and R B 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;

wherein M is a metal having an atomic weight greater than 40;

wherein A is coordinated to M by a non-carbene dative bond;

wherein B is coordinated to M by a polar covalent bond between a carbon atom and M;

wherein M is bonded to one of the five-membered rings of A;

wherein L is a substituted or unsubstituted cyclometalated ligand, and each L can be the same or different; and

wherein m is at least 1, and m+n is the maximum number of ligands that may be attached to M.

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 the 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. A consumer product comprising the OLED of claim 15 .

19. The consumer product of claim 18 , 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 wall comprising multiple displays tiled together, a theater or stadium screen, and a sign.

20. 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 Formula I

wherein A is a fused ring system comprising a six-membered ring, which is fused to a five-membered ring, wherein the five-membered ring is fused to a second five-membered ring;

wherein B is a five-membered or six-membered carbocyclic or heterocyclic ring;

wherein A and B are connected by a single bond between a carbon atom of A and an atom of B;

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

wherein each R A and R B 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;

wherein M is a metal having an atomic weight greater than 40;

wherein A is coordinated to M by a non-carbene dative bond;

wherein B is coordinated to M by a polar covalent bond between a carbon atom and M;

wherein M is bonded to one of the five-membered rings of A;

wherein L is a substituted or unsubstituted cyclometalated ligand, and each L can be the same or different and

wherein m is at least 1, and m+n is the maximum number of ligands that may be attached to M; and

wherein the organic layer further comprises a host, wherein the host is selected from the group consisting of:

and combinations thereof.