Organic electroluminescent materials and devices

A first device comprising an organic light emitting device, the organic light emitting device comprising:

• an anode;
• a cathode;
• and
• an organic layer, disposed between the anode and the cathode, comprising a compound comprising a metal and a ligand LA selected from the group of ligands consisting of:
• wherein Y1, Y2, Y3, Y4, Y5, Y6, Y7, Y8, Y9, Y10, Y11, and Y12 are independently selected from the group consisting of CH, C bonded to metal M, N, and C-APR1′R1″, and the ligand LA is bidentate with a first bond to the metal M formed with the P-atom of the C-APR1′R1″ and a second bond to the metal M formed with a ring carbon of ligand LA5, ligand LA6, ligand LA7, or ligand LA8;
• wherein the metal M has an atomic weight of at least 40;
• wherein exactly one of Y1 through Y8 is C-APR1′R1″ in LA5 and LA6, and exactly one of Y1 through Y8 is the ring carbon bonded to the metal;
• wherein exactly one of Y1 through Y10 is C-APR1′R1″ in LA7, and exactly one of Y1 through Y10 is the ring carbon bonded to the metal;
• wherein exactly one of Y1 through Y12 is C-APR1′R1″ in LA8, and exactly one of Y1 through Y12 is the ring carbon bonded to the metal;
• wherein A is selected from the group consisting of a single bond, —CRARB—, —NRA—, —O—, —S— and —SiRARB—;
• wherein R, R1′, R1″, R2, R3, RA, and RB are each independently selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, and aryl.

A formulation comprising a compound comprising a metal and a ligand LA selected from the group of ligands consisting of:

• wherein Y1, Y2, Y3, Y4, Y5, Y6, Y7, Y8, Y9, Y10, Y11, and Y12 are independently selected from the group consisting of CH, C bonded to metal M, N, and C-APR1′R1″, and the ligand LA is bidentate with a first bond to the metal M formed with the P-atom of the C-APR1′R1″ and a second bond to the metal M formed with a ring carbon of ligand LA5, ligand LA6, ligand LA7, or ligand LA8;
• wherein the metal M has an atomic weight of at least 40;
• wherein exactly one of Y1 through Y8 is C-APR1′R1″ in LA5, and LA6, and exactly one of Y1 through Y8 is the ring carbon bonded to the metal;
• wherein exactly one of Y1 through Y10 is C-APR1′R1″ in LA7, and exactly one of Y1 through Y10 is the ring carbon bonded to the metal;
• wherein exactly one of Y1 through Y12 is C-APR1′R1″ in LA8, and exactly one of Y1 through Y12 is the ring carbon bonded to the metal;
• wherein A is selected from the group consisting of a single bond, —CRARB—, —NRA—, —O—, —S— and —SiRARB—;
• wherein R, R1′, R1″, R2, R3, RA, and RB are each independently selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, and aryl.