Organic electroluminescent materials and devices

1. A compound of Formula I:

wherein:

X 1 -X 8 are each independently C or N, wherein two adjacent X 1 -X 8 are carbon-fused to a structure of Formula II:

X 9 -X 12 are each independently C or N;

A 1 , A 2 , and A 3 are each independently selected from the group consisting of O, S, Se, N, NR, CR, CRR′, SIR, SiRR′, GeR, and GeRR′, with at least one of A 1 and A 2 being N or NR;

each occurrence of is independently a single bond or a double bond, wherein one occurrence of is a single bond and one occurrence of is a double bond;

each of R A , R B , and R C independently represents zero, mono, or up to a maximum allowed substitution to its associated ring;

each of occurrence R, R′, R A , R B , and R C is independently a hydrogen or a substituent selected from the group consisting of Formula III, Formula IV, Formula V, Formula VI, Formula VII, Formula VIII, Formula IX, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, with at least one of R, R′, R A , R B , and R C comprising a group of Formula III, Formula IV, Formula V, Formula VI, Formula VII, Formula VIII, or Formula IX:

each occurrence of Y 1 , Y 2 , and Y 3 is independently absent, O, S, Se, NR, CRR′, SiRR′, or GeRR′;

each occurrence of Ar 1 and Ar 2 is independently an optionally substituted aryl group or an optionally substituted heteroaryl group, wherein Ar 1 and Ar 2 are optionally joined or fused together to form a ring;

each occurrence of X 13 _X 20 is independently C or N;

each occurrence of A 4 is selected from the group consisting of O, S, Se, NR, CRR′, SiRR′, and GeRR′;

each occurrence of R X independently represents zero, mono, or up to a maximum allowed substitution to its associated ring;

each occurrence of R X is independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

each occurrence of R Y is independently a hydrogen or a substituent selected from the group consisting of Formula III, Formula IV, Formula V, Formula VI, Formula IX, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

the maximum number of N atoms that are connected to each other within a ring is two; and

any two substituents are optionally joined or fused together to form a ring.

2. The compound of claim 1 , wherein one of R, R A or R B comprises a group of Formula III:

wherein Y 1 -Y 3 , and R X are each as defined in claim 1 .

3. The compound of claim 2 , wherein each occurrence of R X is independently a hydrogen or a substituent selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, and combinations thereof.

4. The compound of claim 2 , wherein Y 1 , Y 2 , and Y 3 are each independently absent, O or NR, with R being an aryl or heteroaryl group.

5. The compound of claim 2 , wherein Y 1 and Y 2 are each O, and Y 3 is absent.

6. The compound of claim 2 , wherein each occurrence of R X is independently hydrogen, deuterium, alkyl, cycloalkyl, aryl, heteroaryl, or combinations thereof.

7. The compound of claim 1 , wherein one of R, R A or R B has Formula VI:

wherein X 13 -X 20 , A 4 , and R X are each as defined in claim 1 .

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

9. The compound of claim 7 , wherein A 4 is NR.

10. The compound of claim 9 , wherein R is aryl or heteroaryl group.

11. The compound of claim 7 , wherein one of X 13 -X 16 is N.

12. The compound of claim 7 , wherein each occurrence of R X is independently hydrogen, deuterium, alkyl, cycloalkyl, aryl, heteroaryl, or combinations thereof.

13. The compound of claim 1 , wherein one of R, R A or R B has Formula VII or VIII:

wherein R X and R Y are both as defined in claim 1 .

14. The compound of claim 13 , wherein each occurrence of R X is independently a hydrogen or a substituent selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, and combinations thereof.

15. The compound of claim 13 , wherein R Y is a phenyl group.

16. The compound of claim 13 , wherein each occurrence of R X is independently hydrogen, deuterium, alkyl, cycloalkyl, aryl, heteroaryl, or combinations thereof.

17. The compound of claim 7 , wherein A 4 is O.

18. The compound of claim 7 , wherein A 4 is S.

19. The compound of claim 7 , wherein A 4 is Se.

20. The compound of claim 7 , wherein two of X 13 -X 20 are N.