Light-emitting device containing bis-phosphineoxide compound

1. An OLED device comprising an anode and a cathode and having therebetween a light emitting layer containing a host and an emissive material, wherein the host material is a phosphineoxide compound bearing two or more tri(hetero)arylphosphineoxide groups, provided these groups are selected to give a compound with a Et≧2.65 eV.

2. The device of claim 1 that emits light in the green or blue region of the visible spectrum, or together with the emission of another layer, emits white light.

3. The device of claim 1 wherein the device contains an exciton or hole blocking layer located between the cathode and the light emitting layer that contains a phosphineoxide compound bearing two or more tri(hetero)arylphosphineoxide groups, provided these groups are selected to give a compound with a Et≧2.65 eV.

4. The device of claim 3 that emits light in the green or blue region of the visible spectrum, or together with the emission of another layer, emits white light.

5. The device of claim 1 wherein the device contains an electron-transporting layer located between the cathode and the anode and contains a phosphineoxide compound bearing two or more tri(hetero)arylphosphineoxide groups provided the tri(hetero)arylphosphineoxide groups selected to give a compound with a Et≧2.65 eV.

6. The device of claim 1 wherein the phosphineoxide compound is represented by the formula:

(A) n B

wherein each A is independently represented by:

and

n≧2;

wherein Ar 1 , Ar 2 and B each represent groups selected to give a compound with a Et≧2.65 eV and;

Ar 1 , Ar 2 and B are each an aromatic group or heteroaromatic group independently selected from phenyl, biphenyl, and heteroaryl groups which may be independently substituted with one or more of alkyl, alkenyl, alkoxy, aryl, aralkyl, halogen, NH 2 , NHR, NR 2 , NO 2 and CN groups;

provided that one or more of Ar 1 , Ar 2 and B may be linked together by a linking group selected from a covalent bond, —O—, —CH 2 —, —CHR—, —CR 2 —, —NH—, and —NR—in which each R is selected from alkyl, alkenyl, aryl, and aralkyl groups; and

B is a (hetero)aromatic group with n bonds.

7. The device of claim 6 wherein the phosphineoxide compound is represented by the formula:

wherein

B comprises an aromatic group or heteroaromatic group independently selected from phenyl, biphenyl, and heteroaryl with Et≧2.65 eV;

each R is independently selected from alkyl, alkenyl, alkoxy, aryl, aralkyl, halogen, NH 2 , NHR, NR 2 , NO 2 and CN groups;

each of p and m is independently selected from the values 0, 1, 2, 3 and 4; and

n is at least 2.

8. The device of claim 6 wherein B is a chain of 2 or more aromatic ring groups.

9. The device of claim 1 wherein the light emitting layer contains at least two host materials.

10. The device of claim 1 wherein the emissive material is a phosphorescent dye.

11. The device of claim 1 wherein the emissive material is a blue or green phosphorescent dye.

12. The device of claim 1 wherein the light emitted by the device is white.

13. The device of claim 1 wherein Et≧2.8 eV.