Organometallic compounds and emission-shifting organic electrophosphorescence
Emissive phosphorescent organometallic compounds are described that produce improved electroluminescence, particularly in the blue region of the visible spectrum. Organic light emitting devices employing such emissive phosphorescent organometallic compounds are also described. Also described is an organic light emitting layer including a host material having a lowest triplet excited state having a decay rate of less than about 1 per second; a guest material dispersed in the host material, the guest material having a lowest triplet excited state having a radiative decay rate of greater than about 1×10 5 or about 1×10 6 per second and wherein the energy level of the lowest triplet excited state of the host material is lower than the energy level of the lowest triplet excited state of the guest material.
1. A compound having a chemical structure represented by a formula selected from the group consisting of
2. An organic light emitting device having an emissive layer comprising an organometallic compound, wherein the organometallic compound consists of
a metal having an atomic number of at least 72;
at least one mono-anionic, bidentate, carbon coordination ligand bound to the metal, and
at least one non mono-anionic, bidentate, carbon coordination ligand bound to the metal,
wherein the mono-anionic, bidentate, carbon coordination ligand has the structure
wherein R is halogen, alkyl, or aryl, and R 1 , R 2 and R 3 are, independently, hydrogen, halogen, alkyl, or aryl, with the proviso that the at least one mono-anionic, bidentate, carbon-coordination ligand is substituted with at least one of an electron donating substituent and an electron withdrawing substituent.
3. The organic light emitting device of claim 2 , wherein R is halogen.
4. The organic light emitting device of claim 2 , wherein R is alkyl.
5. The organic light emitting device of claim 2 , wherein R is aryl.
6. The organic light emitting device of claim 2 , wherein the metal is selected from the group consisting of Os, Ir, Pt and Au.
7. The organic light emitting device of claim 6 , wherein the metal is selected from the group consisting of Ir and Pt.
8. The organic light emitting device of claim 2 , wherein the non mono-anionic, bidentate, carbon coordination ligand is selected from the group consisting of
wherein E is selected from the group consisting of O, S, Se and Te;
X is selected from the group consisting of CH and N; and
R, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are, independently, hydrogen, halogen, alkyl, or aryl.
9. The organic light emitting device of claim 8 , wherein the non mono-anionic, bidentate, carbon coordination ligand is selected from the group consisting of