Hybrid organic light emitting device

1. An OLED device, comprising:

an anode and a cathode; and

at least one graded emissive layer disposed between the anode and the cathode, the graded emissive layer comprising first and second materials, wherein a concentration of the first material increases continuously from an anode side of the graded emissive layer to a cathode side of the graded emissive layer and a concentration of the second material decreases continuously from the anode side of the graded emissive layer to the cathode side of the graded emissive layer;

wherein the first material has a concentration greater than 10% and less than or equal to 30% on the anode side of the graded emissive layer, and a concentration between 70% and 100% on the cathode side of the graded emissive layer; and

wherein the second material has a concentration greater than or equal to 70% and less than 90% on the anode side of the graded emissive layer and a concentration of between 0% and 30% on the cathode side of the graded emissive layer.

2. The OLED device of claim 1 , wherein the first material has a concentration of about 20% on the anode side of the graded emissive layer and a concentration of about 100% on the cathode side of the graded emissive layer; and

wherein the second material has a concentration of about 80% on the anode side of the graded emissive layer and about 0% on the cathode side of the graded emissive layer.

3. The OLED device of claim 1 , further comprising at least one non-graded emissive layer disposed between the anode and the cathode.

4. The OLED device of claim 3 , wherein the non-graded emissive layer is disposed between the graded emissive layer and the anode.

5. The OLED device of claim 3 , wherein the graded emissive layer is a blue emissive layer and the non-graded emissive layer is selected from the group consisting of a green emissive layer and a red emissive layer.

6. The OLED device of claim 1 , wherein the graded emissive layer is a blue emissive layer.

7. The OLED device of claim 1 , wherein the OLED device is selected from the group consisting of a white OLED and a hybrid white OLED.

8. The OLED device of claim 7 , wherein the graded emissive layer is a blue fluorescent emissive layer, and further comprising red and green phosphorescent emissive layers disposed between the anode and the cathode.

9. The OLED device of claim 1 , wherein the concentration of the first material increases according to a mathematical function, and the concentration of the second material decreases according to the mathematical function; and

wherein the mathematical function is selected from the group consisting of a linear function, a parabolic function, and a logarithmic function.

10. The OLED device of claim 1 wherein at least one of a rate of increasing concentration of the first material and a rate of decreasing concentration of the second material is variable.

11. A product comprising the OLED device of claim 1 , the product selected from the group consisting of a flat panel display, a curved display, a computer monitor, a medical monitor, a television, a billboard, a lights for interior or exterior illumination and/or signaling, a heads-up display, a fully or partially transparent display, a flexible display, a rollable display, a foldable display, a stretchable display, a laser printer, a telephone, a mobile phone, a tablet, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a camcorder, a viewfinder, a micro-display, a 3-D display, a virtual reality display, an augmented reality display, a vehicle, a video wall comprising multiple displays tiled together, a theater or stadium screen, and a sign.

12. An OLED device comprising a graded emissive layer, the graded emissive layer comprising a first material having a first continuous volumetric concentration gradient in a first direction from an anode side to a cathode side of the graded emissive layer, across a thickness of the layer and a second material having a second continuous volumetric concentration gradient opposite the first direction;

wherein the first continuous volumetric concentration gradient begins at a concentration of greater than 10% and less than or equal to 30%, and increases to a concentration between 70% and 100%; and

wherein the second continuous volumetric concentration gradient begins at a concentration of between 0% and 30% and increases to a concentration of greater than or equal to 70% and less than 90%.

13. The OLED device of claim 12 , wherein the graded emissive layer is a blue emissive layer.

14. The OLED device of claim 12 , wherein the OLED device is a white OLED or a hybrid white OLED.

15. The OLED device of claim 6 , wherein the graded emissive layer is a blue fluorescent emissive layer, and further comprising red and green phosphorescent emissive layers.

16. The OLED device of claim 12 , wherein the first and second continuous volumetric gradients are follow a mathematical function selected from the group of linear, parabolic, logarithmic, or variable.

17. A hybrid white OLED device, comprising:

at least red and green phosphorescent emissive layers disposed between the anode and the cathode; and

at least one blue fluorescent graded emissive layer, the graded emissive layer comprising first and second materials and having first and second surfaces facing the anode and cathode, respectively, wherein a concentration of the first material increases continuously from the first surface of the graded emissive layer to the second surface of the graded emissive layer, and a concentration of the second material decreases continuously from the first surface of the graded emissive layer to the second surface of the graded emissive layer;

wherein the first material has a concentration greater than 10% and less than or equal to 30% on the first surface, and a concentration between 70% and 100% on the second surface; and

wherein the second material has a concentration greater than or equal to 70% and less than 90% on the first surface and a concentration of between 0% and 30% on the second surface.