Organic electroluminescent materials and devices

An organic light emitting device (OLED) that includes an anode, a cathode, and

• an organic layer disposed between the anode and the cathode, the organic layer comprising a compound of Formula I
• wherein
• X1 to X8 are independently selected from C or N;
• wherein no more than two of X1 to X4 represent N, and no more than two of X5 to X8 represent N;
• Y is NR2;
• RA and RB represent mono to the maximum allowable substitution, or no substitution;
• and
• each RA, RB, R1, R2, R3, and R4 are independently hydrogen or a substituent selected from the group consisting of deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;
• or optionally, two adjacent substituents of RA and/or RB can join to form a ring;
• wherein R1 comprises a structure selected from the group consisting of formula A, formula B, and formula C
• wherein
• Z is selected from the group consisting of NR5, O, S, Se, and CR6R7;
• wherein R5 is an aromatic linker selected from phenyl, naphthyl, or an aza-analog thereof;
• each R6 and R7 is independently a substituent selected from the group consisting of deuterium, alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof, or optionally, R6 or R7 is an aromatic linker that connects the structure of formula A to Formula I, or the structure of formula C to Formula I;
• X9 to X41 are independently selected from C or N;
• wherein in the structure of formula B, at least one of X17 to X33 is N;
• and in the structure of formula C, at least one of X34 to X41 is N;
• wherein no more than two of X9 to X12 represent N, no more than two of X13 to X16 represent N, no more than two of X17 to X20 represent N, no more than two of X21 to X24 represent N, no more than two of X25 to X28 represent N, no more than two of X29 to X33 represent N, no more than two of X34 to X37 represent N, and no more than two of X38 to X41 represent N;
• RC, RD, RE, RF, RG, RH, RI, and RJ represent mono to the maximum allowable substitution, or no substitution;
• RA, RB, RC, RD, RE, RF, RG, RH, RI, and RJ represent nothing for ring atoms with fully filled valencies;
• and
• each RC, RD, RE, RF, RG, RH, RI, and RJ are independently hydrogen or a substituent selected from the group consisting of deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.