Host materials for electroluminescent devices

An organic light emitting device (OLED) comprising:

• a cathode;
• an anode;
• and
• an emissive layer, disposed between the anode and cathode;
• wherein the emissive layer comprises a composition comprising:
• a first compound capable of functioning as a host in an emissive layer of the OLED at room temperature;
• and
• a second compound comprising a ligand LA of Formula III
• wherein ring A is a 5-membered or 6-membered carbocyclic or heterocyclic ring;
• wherein R represents two adjacent substituents that are joined together to form a ring that is fused to ring B, and R has a structure of Formula IV
• or Formula V
• wherein the wavy lines indicate bonds to ring B;
• wherein RA and RB each independently represents no substitution to a maximum possible number of substitutions on a ring carbon the substituents are attached thereto;
• wherein RA and RB are each independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;
• wherein A1, A2, A3, and A4 are each independently CRC or N;
• wherein Z1, Z2, Z3, and Z4 are each independently C or N;
• wherein at least two adjacent of Z1, Z2, Z3, and Z4 are C and fuse to R;
• wherein when R is Formula V, at least one of A1, A2, A3, A4, Z1, Z2, Z3, and Z4 is N;
• wherein Y is selected from the group consisting of BR′, NW, PR′, O, S, Se, C═O, S═O, SO2, CR′R″, SiR′R″, and GeR′R″;
• wherein RC, R13, R14, R′, and R″ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;
• wherein any two adjacent substituents are optionally joined to form into a ring;
• wherein the ligand LA is coordinated to a metal M;
• wherein M is Ir;
• wherein the ligand LA is optionally linked with other ligands to comprise a tridentate, tetradentate, pentadentate, or hexadentate ligand;
• and
• wherein M is optionally coordinated to other ligands;
• and
• wherein at least one of the following two conditions is true:
• (i) the highest occupied molecular orbital of the first compound has an energy level equal to or less than −5.1 eV;
• and
• (ii) the difference in energy between the highest occupied molecular orbital of the first compound and the highest occupied molecular orbital of the second compound is less than 0.3 eV.

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

• an anode;
• a cathode;
• and
• an emissive layer, disposed between the anode and cathode;
• wherein the emissive layer comprises a composition comprising:
• a first compound capable of functioning as a host in an emissive layer of the OLED at room temperature;
• and
• a second compound comprising a ligand LA of Formula III
• wherein ring A is a 5-membered or 6-membered carbocyclic or heterocyclic ring;
• wherein R represents two adjacent substituents that are joined together to form a ring that is fused to ring B, and R has a structure of Formula IV
• or Formula V
• wherein the wavy lines indicate bonds to ring B;
• wherein RA and RB each independently represents no substitution to a maximum possible number of substitutions on a ring carbon the substituents are attached thereto;
• wherein RA and RB are each independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;
• wherein A1, A2, A3, and A4 are each independently CRC or N;
• wherein Z1, Z2, Z3, and Z4 are each independently C or N;
• wherein at least two adjacent of Z1, Z2, Z3, and Z4 are C and fuse to R;
• wherein when R is Formula V, at least one of A1, A2, A3, A4, Z1, Z2, Z3, and Z4 is N;
• wherein Y is selected from the group consisting of BR′, NW, PR′, O, S, Se, C═O, S═O, SO2, CR′R″, SiR′R″, and GeR′R″;
• wherein RC, R13, R14, R′, and R″ are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;
• wherein any two adjacent substituents are optionally joined to form into a ring;
• wherein the ligand LA is coordinated to a metal M;
• wherein M is Ir;
• wherein the ligand LA is optionally linked with other ligands to comprise a tridentate, tetradentate, pentadentate, or hexadentate ligand;
• and
• wherein M is optionally coordinated to other ligands;
• and
• wherein at least one of the following two conditions is true:
• (i) the highest occupied molecular orbital of the first compound has an energy level equal to or less than −5.1 eV;
• and
• (ii) the difference in energy between the highest occupied molecular orbital of the first compound and the highest occupied molecular orbital of the second compound is less than 0.3 eV.