Organic electroluminescent materials and devices

1. A compound having a formula OsL 1 L 2 ;

wherein L 1 is a tetradentate ligand coordinated to Os;

wherein L 2 is a bidentate ligand coordinated to Os;

wherein L 1 adopts a non-square planar coordination geometry;

wherein L 1 and L 2 in combination comprise six coordinating atoms including two anionic coordinating atoms, and four neutral coordinating atoms;

wherein each of the anionic coordinating atoms is an sp 2 carbon atom selected from the group consisting of benzene, pyridine, furan, thiophene, and pyrrole.

2. The compound of claim 1 , wherein Os is Os(II), and the compound is neutral.

3. The compound of claim 1 , wherein (i) L 1 is dianionic and L 2 is neutral, (ii) L 1 is monoanionic and L 2 is monoanionic, or (i) L 1 is neutral and L 2 is dianionic.

4. The compound of claim 1 , wherein the compound has a structure of Formula I:

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

wherein rings A, B, C, D, E, and F can each be independently further substituted by one or more substituents 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 adjacent substituents on each of rings A, B, C, D, E, and F can optionally be joined to form a ring;

wherein X 1 , X 2 , X 3 , X 4 , X 5 , and X 6 each independently selected from the group consisting of C, N, O, S, and P;

wherein rings A, B, C, and D link together to form a tetradentate ligand L 1 ;

wherein rings E and F link together to from a bidentate ligand L 2 ; and

wherein each arc between rings represents a linking group.

5. The compound of claim 4 , wherein rings A, B, C, and D are each independently selected from phenyl, pyridine, imidazole, benzimidazole, dibenzofuran, dibenzothiophene, carbazole, aza-dibenzofuran, aza-dibenzothiophene, and azacarbazole.

6. The compound of claim 4 , wherein two of X 1 , X 2 , X 3 , X 4 , X 5 , and X 6 are anionic coordinating atoms, and four of X 1 , X 2 , X 3 , X 4 , X 5 , and X 6 are neutral coordinating atoms; and

wherein each of the neutral coordinating atoms is independently selected from the group consisting of: C, P, and N.

7. The compound of claim 6 , wherein the neutral carbon is N-heterocyclic carbene; wherein the neutral phosphorus is a phosphorus atom of a trisubstituted phosphine; and wherein the neutral nitrogen is an sp 2 nitrogen atom of an N-heterocyclic ring selected from the group consisting of pyridine, imidazole, benzimidazole, pyrazole, and triazole.

8. The compound of claim 6 , wherein the anionic coordinating nitrogen is an sp 2 nitrogen atom of an N-heterocyclic ring selected from the group consisting of imidazole, benzimidazole, pyrazole, and triazole.

9. The compound of claim 6 , wherein the anionic oxygen atom is an oxygen atom from a carboxylic acid or ether.

10. The compound of claim 4 , wherein the compound has a structure of Formula II

wherein K BC is a linking group comprising a backbone with at least two atoms connecting Ring B to Ring C.

11. The compound of claim 1 , wherein L 1 comprises a moiety selected from the group consisting of:

wherein n 1 is an integer of 2, 3, or 4, and

wherein n 2 is an integer of 3, 4, 5, or 6.

12. The compound of claim 1 , wherein L 2 comprises a moiety selected from the group consisting of:

wherein n 1 is an integer of 1, 2, 3, or 4.

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

wherein n 1 is an integer of 2, 3, or 4.

14. A first organic light emitting device comprising:

an anode;

a cathode; and

an organic layer, disposed between the anode and the cathode, comprising a compound having a formula OsL 1 L 2 ;

wherein L 1 is a tetradentate ligand coordinated to Os;

wherein L 2 is a bidentate ligand coordinated to Os;

wherein L 1 adopts a non-square planar coordination geometry;

wherein L 1 and L 2 in combination comprise six coordinating atoms including two anionic coordinating atoms, and four neutral coordinating atoms;

wherein each of the anionic coordinating atoms is an sp 2 carbon atom selected from the group consisting of benzene, pyridine, furan, thiophene, and pyrrole.

15. The first organic light emitting device of claim 14 , wherein the first organic light emitting device is incorporated into one of a consumer product, an electronic component module, an organic light-emitting device, and a lighting panel.

16. The first organic light emitting device of claim 14 , wherein the organic layer is an emissive layer and the compound is an emissive dopant or a non-emissive dopant.

17. The first organic light emitting device of claim 14 , 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, aza-dibenzoselenophene,

and combinations thereof.

18. A formulation comprising a compound having a formula OsL 1 L 2 ;

wherein L 1 is a tetradentate ligand coordinated to Os;

wherein L 2 is a bidentate ligand coordinated to Os;

wherein L 1 adopts a non-square planar coordination geometry;

wherein L 1 and L 2 in combination comprise six coordinating atoms including two anionic coordinating atoms, and four neutral coordinating atoms;

wherein each of the anionic coordinating atoms is an sp 2 carbon atom selected from the group consisting of benzene, pyridine, furan, thiophene, and pyrrole.

19. The first organic light emitting device of claim 14 , wherein the organic layer further comprises a host, wherein the host comprises a triphenylene containing benzo-fused thiophene or benzo-fused furan;

wherein any substituent in the host is an unfused substituent independently selected from the group consisting of C n H 2n+1 , OC n H 2n+1 , OAr 1 , N(C n H 2n+1 ) 2 , N(Ar 1 )(Ar 2 ), CH═CH—C n H 2n+1 , C≡CC n H 2n+1 , Ar 1 , Ar 1 —Ar 2 , C n H 2n —Ar 1 , or no substitution;

wherein n is from 1 to 10; and

wherein Ar 1 and Ar 2 are independently selected from the group consisting of benzene, biphenyl, naphthalene, triphenylene, carbazole, and heteroaromatic analogs thereof.

20. The first organic light emitting device of claim 14 , wherein the first organic light emitting device is incorporated in a consumer product that is one of a flat panel 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 laser printer, a telephone, a cell phone, a tablet, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a camcorder, a viewfinder, a micro-display, a 3-D display, a vehicle, a large area wall, a theater or a stadium screen, or a sign.