Non-blocked phosphorescent OLEDs

1. A device comprising:

an anode and a cathode;

an emissive layer disposed between and electrically connected to the anode and the cathode, the emissive layer comprising an organic host and an organic dopant;

an organic hole transport layer between the anode and the emissive layer;

an organic electron transport layer between the cathode and the emissive layer,

an electron injection layer between the cathode and the electron transport layer;

wherein said electron transport layer is a single layer and is the only layer between the electron injection layer and the emissive layer;

the HOMO level of the organic host is no more than 0.8 eV below the HOMO level of the hole transport layer,

the LUMO level of the organic host is no more than 0.4 eV above the LUMO level of the electron transport layer,

the HOMO level of the electron transport layer is no more than 0.4 eV below the HOMO level of the host,

the HOMO and LUMO levels being calculated by density functional calculation, wherein the device has an external quantum efficiency of over 9.2% at 500 cd/m 2 and up to about 30%;

wherein the organic host comprises a carbazole moiety.

2. The device of claim 1 , wherein the organic dopant is a phosphorescent material.

3. The device of claim 2 , wherein the organic dopant has a triplet energy corresponding to a peak emission wavelength of less than 600 nm.

4. The device of claim 3 , wherein the dopant is an iridium(III) organometallic complex.

5. The device of claim 2 , wherein the dopant is Ir(5-Phppy) 3 .

6. The device of claim 2 , wherein the dopant is Ir(3′-Meppy) 3 .

7. The device of claim 2 , wherein there is a triplet recombination zone within the emissive layer, not more than 10% of the thickness of the emissive layer away from an interface between the emissive layer with the hole transport layer.

8. The device of claim 2 , wherein

HOMO

Host

-

HOMO

HoleTransportLayer

LUMO

ElectronTransportLayer

-

LUMO

Host

<

2.0

.

9. A device comprising:

an anode and a cathode;

an emissive layer disposed between and electrically connected to the anode and the cathode, the emissive layer comprising an organic host and an organic dopant;

an organic hole transport layer between the anode and the emissive layer;

an organic electron transport layer between the cathode and the emissive layer,

an electron injection layer between the cathode and the electron transport layer;

wherein said electron transport layer is a single layer and is the only layer between the electron injection layer and the emissive layer;

the HOMO level of the organic host is no more than 0.8 eV below the HOMO level of the hole transport layer,

the LUMO level of the organic host is no more than 0.4 eV above the LUMO level of the electron transport layer, and

the HOMO level of the electron transport layer is no more than 0.4 eV below the HOMO level of the host,

the HOMO and LUMO levels being calculated by density functional calculation,

the organic dopant is a phosphorescent dopant having a triplet energy corresponding to a peak emission wavelength of less than 600 nm, and

the device has an external quantum efficiency of over 9.2% at 500 cd/m 2 and up to about 30%;

wherein the organic host comprises a carbazole moiety.

10. The device of claim 9 , wherein the dopant is Ir(5-Phppy) 3 .

11. The device of claim 9 , wherein the dopant is Ir(3′-Meppy) 3 .

12. The device of claim 9 , wherein there is a triplet recombination zone within the emissive layer, not more than 10% of the thickness of the emissive layer away from an interface between the emissive layer with the hole transport layer.

13. The device of claim 9 , wherein the device has a lifetime >3,000 hours to 80% of an initial luminance of 1,000 cd/m 2 .

14. The device of claim 9 , wherein the device has a lifetime >10,000 hours to 50% of an initial luminance of 1,000 cd/m 2 .

15. A consumer product comprising an organic light-emitting device (OLED) comprising:

an anode and a cathode;

an emissive layer disposed between and electrically connected to the anode and the cathode, the emissive layer comprising an organic host and an organic dopant;

an organic hole transport layer between the anode and the emissive layer;

an organic electron transport layer between the cathode and the emissive layer,

an electron injection layer between the cathode and the electron transport layer;

wherein said electron transport layer is a single layer and is the only layer between the electron injection layer and the emissive layer;

the HOMO level of the organic host is no more than 0.8 eV below the HOMO level of the hole transport layer,

the LUMO level of the organic host is no more than 0.4 eV above the LUMO level of the electron transport layer,

the HOMO level of the electron transport layer is no more than 0.4 eV below the HOMO level of the host,

the HOMO and LUMO levels being calculated by density functional calculation,

wherein the device has an external quantum efficiency of over 9.2% at 500 cd/m 2 and up to about 30%;

wherein the organic host comprises a carbazole moiety.

16. The consumer product of claim 15 , wherein the consumer product is selected from the group consisting of: a flat panel display, a computer monitor, a television, a billboard, a lights for interior or exterior illumination and/or signaling, a heads up display, a fully transparent display, a flexible display, a laser printer, a telephone, a cell phone, a personal digital assistant (PDA), a laptop computer, a digital camera, a camcorder, a viewfinder, a micro-display, a vehicle, a large area wall, theater or stadium screen, a sign, or a combination thereof.