Organic electroluminescent materials and devices

1. A composition comprising a first compound, wherein the first compound is selected from the group consisting of

wherein X 1 , X 2 , and X 3 are each independently CH or N;

wherein at least two of X 1 , X 2 , and X 3 are N;

wherein R A , R B , R C , and R D each independently selected from the group consisting of aryl, heteroaryl, substituted aryl, substituted heteroaryl, and combination thereof;

wherein each R 1 , R 2 and R 3 is independently 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;

wherein in Formula I, R 1 is aryl or heteroaryl, or at least one of R A and R B comprises two or more aromatic rings;

wherein in Formula I, when at least one of R A or R B form dibenzofuran or dibenzothiophene, Formula I bonds to carbon atoms 2, 4, 6, or 8 of the dibenzofuran or dibenzothiophene;

wherein in Formula II, at least one of R C and R D is independently a substituent selected from the group consisting of alkylated aromatic ring and two or more aromatic rings, and

R C and R D are different;

wherein the composition further comprises a second compound selected from the group consisting of:

wherein,

R E to R U each independently represents mono to the maximum allowable substitutions, or no substitution;

each R 4 , R 5 , and R E to R U is independently hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

any two substituents may be joined or fused together to form a ring;

Y is O or S; and

Ar 3 is a substituted or unsubstituted aryl ring.

2. The composition of claim 1 , wherein X 1 , X 2 , and X 3 are N.

3. The composition of claim 1 , wherein the first compound is selected from the group consisting of:

4. The composition of claim 1 , wherein each R 4 , R 5 , and R E to R U is independently 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.

5. The composition of claim 1 , wherein the second compound is selected from the group consisting of:

6. The composition of claim 1 , wherein the first compound has an evaporation temperature T1 of 150 to 350° C.;

wherein the second compound has an evaporation temperature T2 of 150 to 350° C.;

wherein the absolute value of T1−T2 is less than 20° C.;

wherein a ratio stability in a film formed by evaporating the mixture in a vacuum deposition tool at a constant pressure between 1×10 −6 Torr to 1×10 −9 Torr, at a 2 Å/sec deposition rate on a surface position at a predefined distance away from the mixture being evaporated is equal to or less than 1.

7. An organic light emitting device (OLED) comprising:

an anode;

a cathode; and

an organic layer, disposed between the anode and the cathode, comprising the composition of claim 1 .

8. The OLED of claim 7 , wherein the organic layer is an emissive layer and the composition is a host material.

9. The OLED of claim 7 , wherein the organic layer further comprises a phosphorescent emissive dopant; wherein the emissive dopant is a transition metal complex having at least one ligand or part of the ligand if the ligand is more than bidentate selected from the group consisting of:

wherein,

each Y 1 to Y 13 is independently selected from the group consisting of carbon and nitrogen;

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 , SiR e R f , and GeR e R f ;

R e and R f are optionally fused or joined to form a ring;

each R a , R b , R c , and R d independently represents from mono substitution to the maximum allowable substitutions, or no substitution;

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

any two adjacent substituents of R a , R b , R c , and R d can be fused or joined to form a ring or form a multidentate ligand.

10. The OLED of claim 7 , wherein the organic layer is a blocking layer and the composition is a blocking material in the organic layer; or the organic layer is a transporting layer and the composition is a transporting material in the organic layer.

11. A consumer product comprising an organic light-emitting device comprising:

an anode;

a cathode; and

an organic layer, disposed between the anode and the cathode, comprising the composition of claim 1 .