Organic electroluminescent materials and devices

A composition of materials comprising a first compound, wherein the first compound has a formula:

• wherein G1 is selected from the group consisting of dibenzofuran, dibenzothiophene, dibenzoselenophene, and fluorene;
• wherein L1, L2 and L3 are each independently selected from the group consisting of direct bond, phenyl, biphenyl, terphenyl, pyridine, pyrimidine, and combinations thereof;
• wherein G4 is selected from the group consisting of phenyl, biphenyl, terphenyl, naphthalene, phenanthrene, pyridine, pyrimidine, pyrazine, quinoline, isoquinoline, phenanthroline, and combinations thereof;
• wherein G2, G3, and G5 are each independently selected from the group consisting of phenyl, biphenyl, terphenyl, fluorene, naphthalene, phenanthrene, pyridine, pyrimidine, pyrazine, quinoline, isoquinoline, phenanthroline, aza-fluorene, and combinations thereof;
• wherein G2, G3, G4, and G5 are each optionally further substituted with one or more unfused substituents selected from the group consisting of deuterium, alkyl, alkoxyl, cycloalkyl, cycloalkoxyl, halogen, nitro, nitrile, silyl, phenyl, biphenyl, terphenyl, pyridine, and combinations thereof;
• wherein m is an integer from 0 to 7,
• wherein n is an integer from 0 to 4;
• wherein, when m or n is larger than 1, each G4 or G5 can be same or different;
• wherein, when n is 0, m is equal to or greater than 1 and each G4 is selected from the group consisting of phenyl and biphenyl;
• wherein when n is equal to or greater than 1, L1 is not a direct bond;
• wherein m+n is at least 1;
• if L1 is phenyl, then at least one of the following is true:
• (i) n is 0, (ii) n is 1 and G5 is not biphenyl, (iii) m+n is at least 2, or (iv) the composition further comprises a second compound;
• wherein the second compound has a structure of Formula II,
• wherein:
• Ar1 is selected from the group consisting of triphenylene, and aza-triphenylene;
• Ar2 is selected from the group consisting of a direct bond, phenyl, biphenyl, terphenyl, naphthalene, pyridine, dibenzofuran, dibenzothiophene, dibenzoselenophene, aza-dibenzofuran, aza-dibenzothiophene, aza-dibenzoselenophene, and combinations thereof;
• Ar3 is selected from the group consisting of benzene, biphenyl, terphenyl, naphthalene, pyridine, dibenzofuran, dibenzothiophene, dibenzoselenophene, aza-dibenzofuran, aza-dibenzothiophene, aza-dibenzoselenophene, carbazole, aza-carbazole, and combinations thereof;
• and
• Ar1, Ar2 and Ar3 are each, independently, optionally further substituted with one or more substitutions selected from the group consisting of deuterium, halogen, alkyl, aryl, heteroaryl, and combinations thereof.