OLEDs utilizing multidentate ligand systems

An organic light emitting device comprising an anode, a cathode, and an organic layer disposed between the anode and the cathode, wherein the organic layer comprises an emissive material of the formula I

• [Xa—(L)b]M (I)
• wherein
• M is a transition metal having a molecular weight greater than 40, Tl, Pb, Bi, In, Sn, Sb or Te;
• X is a linking group that links two or more L, and is selected from the group consisting of —(CR2)d—, —[O(CR2)e]O—, or a group having the formula
• wherein
• A is —(CR2)j, or -Z-(CR2)g—;
• Z is —O—, —NR—, or —SiR2—;
• B1 is —O—, —NR—, —CR═CR—, aryl, heteroaryl,
• B2 is
• alkyl, aryl, heteroaryl, cycloalkyl, or a heterocyclic group;
• each R is independently selected from H, alkyl, aralkyl, aryl and heteroaryl,
• d is 1 to 6,
• e is 1 to 6,
• f is 1 to 4, and
• g is 1 to 4;
• L is a bidentate ligand selected from the group consisting of
• (i) bidentate photoactive ligands having the formula II
• wherein
• the bidentate photoactive ligand is bound to the transition metal, Tl, Pb, Bi, In, Sn, Sb or Te through a carbon-metal bond and a nitrogen-metal bond to form a cyclometallated ring,
• Y is N or C,
• the dotted line represents an optional double bond,
• R1, R2, R3 and R4 are independently selected from H, alkyl, or aryl, and additionally or alternatively, one or more of R1 and R2, R2 and R3, and R3 and R4 together from independently a 5 or 6-member cyclic group, wherein said cyclic group is cycloalkyl, cycloheteroalkyl, aryl or heteroaryl;
• and wherein said cyclic group is optionally substituted by one or more substituents Z;
• each substituent Z is independently selected from the group consisting of alkyl, alkenyl, alkynyl, aralkyl, CN, CF3, NR2, NO2, OR, halo, and aryl, and additionally, or alternatively, two Z groups on adjacent ring atoms form a fused 5- or 6-membered aromatic group, and
• each R is independently selected from H, alkyl, aralkyl, aryl and heteroaryl;
• and
• (ii) bidentate ancillary ligands,
• a is 1 to 4;
• b is 2 or 3;
• and
• at least one L is selected from a bidentate photoactive ligand.

A compound of the formula I

• [Xa—(L)b]M (I)
• wherein,
• M is a transition metal having a molecular weight greater than 40, Tl, Pb, Bi, In, Sn, Sb or Te;
• X is a linking group that links two or more L, and is selected from the group consisting of —(CR2)d—, —[O(CR2)e]O—, or a group having the formula
• wherein
• A is —(CR2)j, or -Z-(CR2)g—;
• Z is —O—, —NR—, or —SiR2—;
• B1 is —O—, —NR—, —CR═CR—, aryl, heteroaryl, cycloalkyl, or a heterocyclic group,
• B2 is
• alkyl, aryl, heteroaryl, cycloalkyl, or a heterocyclic group;
• each R is independently selected from H, alkyl, aralkyl, aryl and heteroaryl,
• d is 1 to 6,
• e is 1 to 6,
• f is 1 to 4, and
• g is 1 to 4;
• L is a bidentate ligand selected from the group consisting of
• (i) bidentate photoactive ligands having the formula II
• wherein
• the bidentate photoactive ligand is bound to the transition metal, Tl, Pb, Bi, In, Sn, Sb or Te through a carbon-metal bond and a nitrogen-metal bond to form a cyclometallated ring,
• Y is N or C,
• the dotted line represents an optional double bond,
• R1, R2, R3 and R4 are independently selected from H, alkyl, or aryl, and additionally or alternatively, one or more of R1 and R2, R2 and R3, and R3 and R4 together from independently a 5 or 6-member cyclic group, wherein said cyclic group is cycloalkyl, cycloheteroalkyl, aryl or heteroaryl;
• and wherein said cyclic group is optionally substituted by one or more substituents Z;
• each substituent Z is independently selected from the group consisting of alkyl, alkenyl, alkynyl, aralkyl, CN, CF3, NR2, NO2, OR, halo, and aryl, and additionally, or alternatively, two Z groups on adjacent ring atoms form a fused 5- or 6-membered aromatic group, and
• (ii) bidentate ancillary ligands,
• each R is independently selected from H, alkyl, aralkyl, aryl and heteroaryl;
• a is 1 to 4;
• b is 2 or 3;
• and
• at least one L is selected from a bidentate photoactive ligand.

An organic light emitting device comprising an anode, a cathode, and an organic layer disposed between the anode and the cathode, wherein the organic layer comprises a metal complex comprising:

• a metal;
• a first ligand bound to the metal, wherein the first ligand is a bidentate ligand;
• a second ligand bound to the metal;
• and
• a linking group that covalently links the first ligand and the second ligand,
• wherein the linking group provides no iL-conjugation between the first ligand and the second ligand;
• and wherein the metal complex is a phosphorescent organometallic emissive material.

A compound of the formula

• [Xa—(L)b]M
• wherein M is a transition metal, Tl, Pb, Bi, In, Sn, Sb or Te;
• L is a bidentate ligand;
• X is a linking group that links two or more L;
• a is 1 to 4,
• b is 2 or 3
• wherein the bidentate ligands are selected from bidentate photoactive ligands, and bidentate ancillary ligands wherein at least one of the bidentate ligands is a bidentate photoactive ligand bound to the transition metal, Tl, Pb, Bi, In, Sn. Sb or Te through a carbon-metal bond;
• and
• wherein the compound is a phosphorescent emissive material.