Organic electroluminescent materials and devices
A compound including a ligand having the formula: is disclosed. In these formulas, each R 1 , R 2 , and R 3 is independently selected from hydrogen, alkyl, and aryl; at least one of R 1 and R 2 is a branched alkyl containing at least 4 carbon atoms, where the branching occurs at a position further than the benzylic position; where R 1 and R 3 are mono-, di-, tri-, tetra-, or no substitutions; and R 2 is mono-, di-, or no substitutions. Heteroleptic iridium complexes including such compounds, and devices including such compounds are also disclosed.
1. An iridium compound having the formula:
wherein n is 1, 2 or 3;
each of R 1 , R 2 , and R 3 is independently a hydrogen, or a mono-, di-, tri-, tetra-, or penta-substitution of alkyl or aryl;
at least one of R 1 , R 2 , and R 3 is a branched alkyl containing at least 4 carbon atoms, and
wherein the branching occurs at a position further than the benzylic position; and
X—Y is an ancillary ligand.
2. The compound of claim 1 , wherein the branched alkyl is an isobutyl group.
3. The compound of claim 1 , wherein X—Y is acac.
4. The compound of claim 1 , selected from the group consisting of:
5. A compound including a ligand having the formula:
each of R 1 , R 2 , and R 3 is independently a hydrogen, or a mono-, di-, tri-, tetra-, or penta-substitution of alkyl or aryl;
at least one of R 1 , R 2 , and R 3 is a branched alkyl containing at least 4 carbon atoms, and wherein the branching occurs at a position further than the benzylic position.
6. The compound of claim 5 , wherein the ligand is coordinated to a metal having an atomic number greater than 40.
7. The compound of claim 5 , wherein the metal is Ir.
8. An organic light emitting device comprising:
an anode;
a cathode; and
an emissive organic layer, disposed between the anode and the cathode, the organic layer further comprising a compound having the formula:
wherein n is 1, 2 or 3;
each of R 1 , R 2 , and R 3 is independently a hydrogen, or a mono-, di-, tri-, tetra-, or penta-substitution of alkyl or aryl;
at least one of R 1 , R 2 , and R 3 is a branched alkyl containing at least 4 carbon atoms, and
wherein the branching occurs at a position further than the benzylic position; and
X—Y is an ancillary ligand.
9. The device of claim 8 , wherein the organic emissive layer further comprises BAlq or
10. The device of claim 8 , wherein the branched alkyl is an isobutyl group.
11. The device of claim 8 , wherein X—Y is acac.
12. The device of claim 8 , selected from the group consisting of: