Organic electroluminescent materials and devices

1. A compound comprising a ligand L selected from the group A consisting of:

wherein each X 1 to X 13 are independently carbon or nitrogen;

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 each R a , R b , R c , and R d are 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, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein when R a , R b , R c , and R d represent at least di substitution, each of the two adjacent R a , two adjacent R b , two adjacent R c , and two adjacent R d are optionally fused or joined to form a ring;

wherein the ligand L is coordinated to a metal M selected from the group consisting of Ir, Rh, Re, Ru, Os, Pt, Au, and Cu;

and the ligand L is optionally linked with other ligands to form a tridentate, tetradentate, pentadentate or hexadentate ligand to the metal M;

wherein the compound comprises at least one intramolecular hydrogen bonding interaction as shown in the scheme:

Z 1 —H—Z 2 ,  scheme 1;

wherein Z 1 is a carbon of an alkyl group directly bonded to one of X 1 to X 13 ;

wherein Z 2 is nitrogen and is one of X 1 to X 13 ; and

wherein in scheme 1, the proton NMR chemical shift of H is shifted downfield by at least 1.3 ppm compared to the compound when Z 2 is carbon.

2. The compound of claim 1 , wherein in scheme 1, the proton NMR chemical shift of H is shifted downfield by at least 1.4 ppm compared to the compound when Z 2 is carbon.

3. The compound of claim 1 , wherein the compound has an emission with the first peak wavelength at the high energy end smaller at room temperature than that at 77K.

4. The compound of claim 1 , wherein Z 1 is carbon of alkyl, and Z 2 is nitrogen of pyridine.

5. The compound of claim 1 , wherein M is Pt and the ligand L is selected from

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

7. The compound of claim 1 , wherein the compound has a formula of Ir(L) n (L′) 3-n ;

wherein the ligand L is different from L′; and

n is 1, 2, or 3.

8. The compound of claim 7 , wherein n is 3.

9. The compound of claim 1 , wherein the compound has a formula of Pt(L) m (L′) 2-m ;

wherein the ligand L is different from L′, and L and L′ are connected to form a tetradentate ligand; and

m is 1, or 2.

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

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

12. A first device comprising a first organic light emitting device, the first organic light emitting device comprising:

an anode;

a cathode; and

an organic layer, disposed between the anode and the cathode, comprising a compound comprising a ligand L selected from the group A consisting of:

wherein each X 1 to X 13 are independently carbon or nitrogen;

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

wherein each R a , R b , R c , and R d are 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, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein when R a , R b , R c , and R d represent at least di substitution, each of the two adjacent R a , two adjacent R b , two adjacent R c , and two adjacent R d are optionally fused or joined to form a ring;

wherein the ligand L is coordinated to a metal M selected from the group consisting of Ir, Rh, Re, Ru, Os, Pt, Au, and Cu;

and the ligand L is optionally linked with other ligands to form a tridentate, tetradentate, pentadentate or hexadentate ligand to the metal M;

wherein the compound comprises at least one intramolecular hydrogen bonding interaction as shown in the scheme:

Z 1 —H—Z 2 ,  scheme 1;

wherein Z 1 is a carbon of an alkyl group directly bonded to one of X 1 to X 13 ;

wherein Z 2 is nitrogen and is one of X 1 to X 13 ; and

wherein in scheme 1, the proton NMR chemical shift of H is shifted downfield by at least 1.3 ppm compared to the compound when Z 2 is carbon.

13. The first device of claim 12 , wherein the first device is selected from the group consisting of a consumer product, an electronic component module, an organic light-emitting device, and a lighting panel.

14. The first device of claim 12 , wherein the organic layer is an emissive layer and the compound is an emissive dopant or a non-emissive dopant.

15. The first device of claim 12 , 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.

16. The first device of claim 12 , 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, dibenzothiphene, dibenzofuran, dibenzoselenophene, azatriphenylene, azacarbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene.

17. The first device of claim 12 , wherein the organic layer further comprises a host and the host is selected from the group consisting of:

and combinations thereof.

18. The first device of claim 12 , wherein the ligand L is selected from the group consisting of:

19. The first device of claim 12 , wherein the compound is selected from the group consisting of: