Organic electroluminescent materials and devices

1. A composition comprising: a mixture of a first compound and a second compound;

wherein the first compound has a different chemical structure than the second compound;

wherein the first compound is capable of functioning as a phosphorescent emitter in an organic light emitting device at room temperature;

wherein the first compound has an evaporation temperature T 1 of 150 to 350° C.;

wherein the second compound has an evaporation temperature T 2 of 150 to 350° C., wherein the evaporation temperature of a compound is measured in a vacuum deposition tool at a constant pressure, between 1×10 −7 Torr to 1×10 −8 Torr, at a 2 Å/sec deposition rate on a surface positioned at a set distance away from the evaporating compound;

wherein the absolute value of T 1 −T 2 is less than 20° C.;

wherein the first compound has a concentration C 1 in said mixture and a concentration C 2 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 2Å/sec deposition rate on a surface position at a predefined distance away from the mixture being evaporated; and

wherein the absolute value of (C 1 −C 2 )/C 1 is less than 5%;

wherein the first compound has a structure according to Formula I:

wherein

R A represents mono, di, tri, tetra, penta, hexa substitutions, or no substitution;

R B represents mono, di, tri, tetra substitutions, or no substitution;

R A , R B , R C , R D , and R E are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, cyclic amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

wherein n is 1 or 2;

wherein the second compound has a structure according to Formula II:

wherein X 1 , X 2 , X 3 , X 4 , X 5 , X 6 , X 7 , Y 1 , Y 2 , and Y 3 are each independently selected from the group consisting of CR and N;

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

wherein R 1 , R 4 and R 5 are independently selected from group consisting of non-fused aryl, non-fused heteroaryl, and combinations thereof;

wherein L is selected from the group consisting of a direct bond, non-fused aryl, non-fused heteroaryl, and combinations thereof; and

wherein each R is independently selected from the group consisting of hydrogen, deuterium, non-fused aryl, non-fused heteroaryl and combinations thereof.

2. The composition of claim 1 , wherein the first compound has a vapor pressure of P 1 at T 1 at 1 atm, the second compound has a vapor pressure of P 2 at T 2 at 1 atm; and

wherein the ratio of P 1 /P 2 is within the range of 0.90 to 1.10.

3. The composition of claim 1 , wherein the first compound has a first mass loss rate and the second compound has a second mass loss rate, wherein the ratio between the first mass loss rate and the second mass loss rate is within the range of 0.90 to 1.10.

4. The composition of claim 1 , wherein the phosphorescent emitter is capable of emitting light from a triplet excited state to a ground singlet state at room temperature.

5. The composition of claim 1 , wherein the second compound is capable of functioning as a host in an organic light emitting device at room temperature.

6. The composition of claim 1 , wherein the composition is in liquid form at a temperature less than T 1 and T 2 .

7. The composition of claim 1 , wherein R 1 is selected from the group consisting of phenyl, biphenyl, terphenyl, tetraphenyl, pentaphenyl, pyridine, phenyl pyridine and pyridyl phenyl.

8. The composition of claim 1 , wherein L is selected from the group consisting of phenyl, pyridyl, biphenyl, terphenyl and a direct bond.

9. The composition of claim 1 , wherein R 4 and R 5 are each independently selected from the group consisting of phenyl, pyridyl, biphenyl, and terphenyl.

10. The composition of claim 1 , wherein the second compound has a structure according to Formula III:

wherein R 2 and R 3 are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, cyclic amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

11. The composition of claim 10 , wherein R 2 and R 3 are each independently selected from the group consisting of hydrogen, deuterium, non-fused aryl, non-fused heteroaryl and combinations thereof.

12. The composition of claim 10 , wherein the second compound has a structure selected from the group consisting of:

13. The composition of claim 1 , wherein n is 1.

14. The composition of claim 1 , wherein R A , R B , R C , R D , and R E are each independently selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, and combinations thereof.

15. The composition of claim 1 , wherein at least one of R C and R E contains a branched alkyl moiety with branching at a position further than the α position to the carbonyl group.

16. The composition of claim 1 , wherein R D is hydrogen.

17. The composition of claim 1 , wherein at least one of R C and R E has the following structure:

wherein R F , and R G are independently selected from group consisting of alkyl and cycloalkyl; and

wherein at least one of R F , and R G has at least two C.

18. The composition of claim 1 , wherein the first compound has a structure according to Formula IV:

wherein R H and R J are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, cyclic amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.

19. The composition of claim 18 , wherein R H and R J are each independently selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, and combinations thereof.

20. The composition of claim 18 , wherein R H and R J are methyl.

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

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

23. The composition of claim 1 , wherein the mixture of the first compound and the second compound is selected from the group consisting of: (Compound E5

24. The composition of claim 1 , wherein the mixture of the first compound and the second compound is

25. 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 first composition comprising a mixture of a first compound and a second compound, wherein the first compound has different chemical structure than the second compound;

wherein the first compound is capable of functioning as a phosphorescent emitter in an organic light emitting device at room temperature;

wherein the first compound has evaporation temperature of T 1 150 to 350° C.;

wherein the second compound has evaporation temperature of T 2 150 to 350° C., wherein the evaporation temperature of a compound is measured in a vacuum deposition tool at a constant pressure, between 1×10 −7 Torr to 1×10 −8 Torr, at a 2 Å/sec deposition rate on a surface positioned at a set distance away from the evaporating compound;

wherein the absolute value of T 1 −T 2 is less than 20° C.;

wherein the first compound has a concentration C 1 in said mixture, and a concentration C 2 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 positioned at a predefined distance away from the mixture being evaporated; and

wherein absolute value of (C 1 −C 2 )/C 1 is less than 5%;

wherein the first compound has a structure according to Formula I:

wherein

R A represents mono, di, tri, tetra, penta, hexa substitutions, or no substitution;

R B represents mono, di, tri, tetra substitutions, or no substitution;

R A , R B , R C , R D , and R E are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, cyclic amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

wherein n is 1 or 2;

wherein the second compound has a structure according to Formula II:

wherein X 1 , X 2 , X 3 , X 4 , X 5 , X 6 , X 7 , Y 1 , Y 2 , and Y 3 are each independently selected from the group consisting of CR and N;

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

wherein R 1 , R 4 and R 5 are independently selected from group consisting of non-fused aryl, non-fused heteroaryl, and combinations thereof;

wherein L is selected from the group consisting of a direct bond, non-fused aryl, non-fused heteroaryl, and combinations thereof; and

wherein each R is independently selected from the group consisting of hydrogen, deuterium, non-fused aryl, non-fused heteroaryl and combinations thereof.

26. A method for fabricating an organic light emitting device comprising a first electrode, a second electrode, and a first organic layer disposed between the first electrode and the second electrode, wherein the first organic layer comprises a first composition comprising a mixture of a first compound and a second compound, the method comprising:

providing a substrate having the first electrode disposed thereon;

depositing the first composition over the first electrode; and

depositing the second electrode over the first organic layer, wherein the first compound has different chemical structure than the second compound;

wherein the first compound is capable of functioning as a phosphorescent emitter in an organic light emitting device at room temperature;

wherein the first compound has an evaporation temperature T 1 of 150 to 350° C.;

wherein the second compound has an evaporation temperature T 2 of 150 to 350° C., wherein the evaporation temperature of a compound is measured in a vacuum deposition tool at a constant pressure, between 1×10 −7 Torr to 1×10 −8 Torr, at a 2 Å/sec deposition rate on a surface positioned at a set distance away from the evaporating compound;

wherein absolute value of T 1 −T 2 is less than 20° C.;

wherein the first compound has a concentration C 1 in said mixture, and a concentration C 2 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 positioned at a predefined distance away from the material; and

wherein absolute value of (C 1 −C 2 )/C 1 is less than 5%;

wherein the first compound has a structure according to Formula I:

wherein

R A represents mono, di, tri, tetra, penta, hexa substitutions, or no substitution;

R B represents mono, di, tri, tetra substitutions, or no substitution;

R A , R B , R C ,R D , and R E are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, cyclic amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

wherein n is 1 or 2;

wherein the second compound has a structure according to Formula II:

wherein X 1 , X 2 , X 3 , X 4 , X 5 , X 6 , X 7 , Y 1 , Y 2 , and Y 3 are each independently selected from the group consisting of CR and N;

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

wherein R 1 , R 4 and R 5 are independently selected from group consisting of non-fused aryl, non-fused heteroaryl, and combinations thereof;

wherein L is selected from the group consisting of a direct bond, non-fused aryl, non-fused heteroaryl, and combinations thereof; and

wherein each R is independently selected from the group consisting of hydrogen, deuterium, non-fused aryl, non-fused heteroaryl and combinations thereof.