Organic electroluminescent materials and devices

A composition comprising, a mixture of a first compound and a second compound;

• wherein the first compound has a structure of Formula I:
• wherein the second compound has a structure of Formula II:
• wherein L1, L2, L3 and L4 are each independently selected from the group consisting of direct bond, alkyl, alkenyl, alkynyl, aryl, heteroaryl, and combinations thereof;
• wherein G1 and G2 are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, alkyloxy, cycloalkyl, cycloalkoxyl, silyl, amino, benzene, biphenyl, terphenyl, naphthalene, triphenylene, pyrene, anthracene, phenanthrene, fluoranthene, fluorene, dibenzofuran, dibenzothiophene, dibenzoselenophene, carbazole, and combinations thereof;
• wherein G3 is selected from the group consisting of pyridine, pyramidine, pyrazine, triazine, quinoline, isoquinoline, quinazoline, quinoxaline, benzimidazole, aza-triphenylene, phenanthroline, aza-pyrene, aza-anthracene, aza-fluorene, aza-dibenzofuran, aza-dibenzothiophene, aza-dibenzoselenophene, aza-carbazole, and combinations thereof;
• wherein G4 is selected from the group consisting of hydrogen, deuterium, halogen, alkyl, alkyloxy, cycloalkyl, cycloalkoxyl, silyl, amino, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl and combinations thereof;
• wherein G3 is optionally further substituted with substituent selected from the group consisting of hydrogen, deuterium, halogen, alkyl, alkyloxy, cycloalkyl, cycloalkoxyl, silyl, amino, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl and combinations thereof;
• wherein R1, R2, R3, R4, R5 and R6 each independently represents mono to maximum allowable substitutions, or no substitution;
• and
• wherein R1, R2, R3, R4, R5 and R6 are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkyloxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, and wherein any two adjacent substituents optionally join or fuse into a ring;
• wherein (i) the first compound is selected from the group consisting of Specific First Compounds, (ii) the second compound is selected from the group consisting of Specific Second Compounds, or (iii) both;
• wherein the Specific First Compounds are defined as the following compounds:
• and
• the Specific Second Compounds are defined as the following commpounds: