Organic electroluminescent materials and devices

1. A compound having the structure of formula (L) n (L′) 3-n Ir, wherein n is 1 or 2, ligand L has a structure

and ligand L′ has a structure selected from the group consisting of:

wherein each A is independently a 5-membered or 6-membered aromatic or heteroaromatic ring;

wherein R A is a substituent having the structure

wherein R A is fused to the pyridine ring of FORMULA I and the dashed line in R A indicates where R A is fused to the pyridine ring of FORMULA I;

wherein each X is independently selected from the group consisting of CRR″, C═O, BR, O, S, and Se;

wherein each R and R′ is independently selected from hydrogen and alkyl;

wherein each R 1 , R 3 , R 4 , and R 5 may independently represent mono, di, tri, or tetra substitutions;

wherein R 2 may represent mono or di substitutions;

wherein each of R 1 , R 7 , R 3 , R 4 , and R 5 are independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, aryl, and heteroaryl; and

wherein the compound is heteroleptic.

2. The compound of claim 1 , wherein ligand L′ is

3. The compound of claim 2 , wherein the compound is selected from the group consisting of:

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

5. The compound of claim 1 , wherein X is S.

6. The compound of claim 1 , wherein X is CRR′.

7. The compound of claim 1 , wherein X is CO.

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

9. The compound of claim 8 , wherein the compound is selected from the group consisting of Compound 1-Compound 12.

10. The compound of claim 8 , wherein the compound is selected from the group consisting of Compound 13-Compound 24.

11. The compound of claim 8 , wherein the compound is selected from the group consisting of Compound 37-Compound 48.

12. The compound of claim 8 , wherein the compound is selected from the group consisting of Compound 49-Compound 60.

13. An organic light emitting device, comprising:

an anode;

a cathode; and

an organic layer disposed between the anode and the cathode, the organic layer comprising a compound having the structure of formula (L) n (L′) 3-n Ir, wherein n is 1 or 2, ligand L has a structure

 and ligand L′ has a structure selected from the group consisting of:

wherein each A is independently a 5-membered or 6-membered aromatic or heteroaromatic ring;

wherein R A is a substituent having the structure

wherein R A is fused to the pyridine ring of FORMULA I and the dashed line in R A indicates where R A is fused to the pyridine ring of FORMULA I;

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

wherein each R and R′ is independently selected from hydrogen and alkyl;

wherein each R 1 , R 3 , R 4 , and R 5 may independently represent mono, di, tri, or tetra substitutions;

wherein R 2 may represent mono or di substitutions;

wherein each of R 1 , R 2 , R 3 , R 4 , and R 5 are independently selected from the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl, arylalkyl, aryl, and heteroaryl; and

wherein the compound is heteroleptic.

14. The device of claim 13 , wherein the organic layer is an emissive layer and the compound is an emitting dopant.

15. The device of claim 13 , wherein the organic layer further comprises a host.

16. The device of claim 15 , wherein the host has the formula:

wherein R′ 2 and R′ 4 may represent mono, di, or tri substitutions;

wherein R′ 1 , R′ 3 , R′ 5 , and R′ 6 may represent mono, di, tri, or tetra substitutions; and

wherein each of R′ 1 , R′ 2 , R′ 3 , R′ 4 , R′ 5 , and R′ 6 are each independently selected from the group consisting of hydrogen, alkyl and aryl.

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