ORGANIC ELECTROLUMINESCENT MATERIALS AND DEVICES

1 . A compound comprising the formula:

wherein:

each of X 5 to X 20 is independently C or N;

R 6 , R 7 , R 8 and R 9 each independently represent zero, mono, or up to the maximum allowed number of substitutions to its associated ring;

each of R 6 , R 7 , R 8 , R 9 and R 10 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, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

wherein R 10 is a substituted biphenyl bonded at a first position of the substituted biphenyl;

wherein the substituted biphenyl is substituted with at least one carbazole at a second position of the substituted biphenyl; and

wherein the first position is para to the phenyl-phenyl bond of the substituted biphenyl, the second position is para to the phenyl-phenyl bond of the substituted biphenyl, or both.

2 . The compound of claim 1 , wherein the substituted biphenyl R 10 is substituted with at least two carbazole moieties.

3 . The compound of claim 1 , wherein the substituted biphenyl R 10 is substituted with an unsubstituted carbazole.

4 . The compound of claim 1 , wherein the substituted biphenyl R 10 is a dicarbazole biphenyl.

5 . The compound of claim 1 , wherein each phenyl of the substituted biphenyl R 10 is substituted with at least one carbazole.

6 . The compound of claim 1 , wherein at least one phenyl of the substituted biphenyl R 10 is substituted with at least two carbazole moieties.

7 . The compound of claim 1 , wherein the substituted biphenyl R 10 is [1,1′-biphenyl]-4-yl that is substituted by at least one carbazole.

8 . The compound of claim 1 , wherein the first position is para to the phenyl-phenyl bond of the substituted biphenyl.

9 . The compound of claim 1 , wherein the second position is para to the phenyl-phenyl bond of the substituted biphenyl.

10 . The compound of claim 1 , wherein the compound comprises a 3,9 biscarbazole.

11 . The compound of claim 1 , wherein the compound comprises at least four carbazole moieties.

12 . The compound of claim 1 , wherein the compound is partially or fully deuterated.

13 . The compound of claim 1 , wherein, when any of R 6 , R 7 , R 8 , R 9 and R 10 comprises heteroaryl, each heteroaryl is independently selected from the group consisting of dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine, preferably dibenzothiophene, dibenzofuran, dibenzoselenophene, carbazole, indolocarbazole, imidazole, benzimidazole, 1,2-azaborine, 1,3-azaborine, 1,4-azaborine, borazine, and aza-analogs thereof, which may be optionally substituted.

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

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

an anode;

a cathode; and

an emissive layer disposed between the anode and the cathode, the emissive layer comprising a host compound, wherein the host compound comprises a formula,

 wherein:

each of X 5 to X 20 is independently C or N;

R 6 , R 7 , R 8 and R 9 each independently represent zero, mono, or up to the maximum allowed number of substitutions to its associated ring;

each of R 6 , R 7 , R 8 , R 9 and R 10 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, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

wherein R 10 is a substituted biphenyl bonded at a first position of the substituted biphenyl;

wherein the substituted biphenyl is substituted with at least one carbazole at a second position of the substituted biphenyl; and

wherein the first position is para to the phenyl-phenyl bond of the substituted biphenyl, the second position is para to the phenyl-phenyl bond of the substituted biphenyl, or both.

16 . The OLED of claim 15 , wherein the host compound is selected from the group consisting of

17 . The OLED of claim 15 , wherein the emissive layer comprises an additional compound, and the additional compound is also a co-host which comprises a chemical moiety selected from the group consisting of triphenylene, carbazole, indolocarbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, pyridine, pyrimidine, triazine, 5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracene, aza-triphenylene, aza-carbazole, aza-indolocarbazole, aza-dibenzothiophene, aza-dibenzofuran, aza-dibenzoselenophene, and aza-(5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracene).

18 . A consumer product comprising an organic light emitting device (OLED) comprising:

an anode;

a cathode; and

an emissive layer disposed between the anode and the cathode, the emissive layer comprising a host compound, wherein the host compound comprises a formula,

 wherein:

each of X 5 to X 20 is independently C or N;

R 6 , R 7 , R 8 and R 9 each independently represent zero, mono, or up to the maximum allowed number of substitutions to its associated ring;

each of R 6 , R 7 , R 8 , R 9 and R 10 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, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

wherein R 10 is a substituted biphenyl bonded at a first position of the substituted biphenyl;

wherein the substituted biphenyl is substituted with at least one carbazole at a second position of the substituted biphenyl; and

wherein the first position is para to the phenyl-phenyl bond of the substituted biphenyl, the second position is para to the phenyl-phenyl bond of the substituted biphenyl, or both.

19 . The consumer product of claim 18 , wherein the host compound is selected from the group consisting of

20 . The consumer product of claim 18 , wherein the consumer product is selected from the group consisting of a flat panel display, a computer monitor, a medical monitor, a television, a billboard, a light for interior or exterior illumination and/or signaling, a heads-up display, a fully or partially transparent display, a flexible display, a laser printer, a telephone, a cell phone, tablet, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a camcorder, a viewfinder, a micro-display, a 3-D display, a virtual reality or augmented reality display, a vehicle, a large area wall, a theater or stadium screen, and a sign.