Light emitting devices with multiple light emitting layers to achieve broad spectrum
View Patent ↗What is disclosed is an organic electroluminescent device which produces a white output spectrum. A plurality of emissive layers, each emitting in a particular spectrum, are fabricated together in one device by choosing materials with solubility properties that do not affect adjacent layers.
1. An organic electroluminescent device, comprising:
a first emissive layer capable of emitting light in a first spectrum;
a second emissive layer disposed over said first emissive layer, said first emissive layer having a solubility characteristic insoluble to the material used in fabricating said second emissive layer, wherein said second emissive layer is capable of emitting light in a second spectrum; and
a third emissive layer disposed over said second emissive layer, said second emissive layer having a solubility characteristic insoluble to the material used in fabricating said third emissive layer, wherein said third emissive layer is capable of emitting light in a third spectrum, wherein each of said first emissive layer, said second emissive layer and said third emissive layer includes at least one selected from the group consisting of a polymer, polymer blend, and co-polymer and wherein the at least one of a polymer, polymer blend and co-polymer of the first emissive layer does not dissolve or degrade in a solvent used in fabricating the second emissive layer and the at least one of the polymer, polymer blend and co-polymer of the second emissive layer does not dissolve or degrade in a solvent used in fabricating the third emissive layer.
2. A device according to claim 1 further comprising a substrate; and
an anode disposed over said substrate.
3. A device according to claim 2 further comprising a hole transporting layer, said hole transporting layer disposed between said anode and said first emissive layer.
4. A device according to claim 2 further comprising a electron transporting layer, said electron transporting layer disposed over said third emissive layer.
5. A device according to claim 2 further comprising a cathode layer, said cathode layer disposed over said third emissive layer.
6. A device according to claim 4 further comprising a cathode layer, said cathode layer disposed over said electron transporting layer.
7. A device according to claim 1 wherein said first spectrum, said second spectrum and said third spectrum combine such that a combined output spectrum of said device is white.
8. A device according to claim 1 wherein at least one of said first, second and third emissive layers comprises a conjugated polymer layer.
9. A device according to claim 1 wherein said first emissive layer, said second emissive layer and said third emissive layer additionally includes a monomer, oligomer, or an organic side-group.
10. A device according to claim 1 wherein said first spectrum includes green.
11. A device according to claim 10 wherein said second spectrum includes blue.
12. A device according to claim 11 wherein said third spectrum includes at least one of red, orange and yellow.
13. A device according to claim 10 wherein said second spectrum includes at least one of red, orange and yellow.
14. A device according to claim 11 wherein said third spectrum includes blue.
15. A device according to claim 1 wherein said first spectrum includes blue.
16. A device according to claim 15 wherein said second spectrum includes green.
17. A device according to claim 16 wherein said third spectrum includes at least one of red, orange and yellow.
18. A device according to claim 15 wherein said second spectrum includes at least one of red, orange and yellow.
19. A device according to claim 16 wherein said third spectrum includes green.
20. A device according to claim 1 wherein said first spectrum includes at least one of red, orange and yellow.
21. A device according to claim 20 wherein said second spectrum includes green.
22. A device according to claim 21 wherein said third spectrum includes blue.
23. A device according to claim 20 wherein said second spectrum includes blue.
24. A device according to claim 21 wherein said third spectrum includes green.
25. A method for fabricating an organic electroluminescent device, said method comprising:
fabricating a first emissive layer capable of emitting light in a first spectrum;
fabricating a second emissive layer disposed over said first emissive layer, said first emissive layer having a solubility characteristic insoluble to the material used in fabricating said second emissive layer, wherein said second emissive layer is capable of emitting light in a second spectrum; and
fabricating a third emissive layer disposed over said second emissive layer, said second emissive layer having a solubility characteristic insoluble to the material used in fabricating said third emissive layer, wherein said third emissive layer is capable of emitting light in a third spectrum, wherein each of said first emissive layer, said second emissive layer and said third emissive layer includes at least one selected from a group consisting of a polymer, polymer blend, and co-polymer and wherein the at least one of a polymer, polymer blend and co-polymer of the first emissive layer does not dissolve or degrade in a solvent used in fabricating the second emissive layer and the at least one of the polymer, polymer blend and co-polymer of the second emissive layer does not dissolve or degrade in a solvent used in fabricating the third emissive layer.
26. A method according to claim 25 further comprising fabricating a substrate; and
fabricating an anode disposed over said substrate.
27. A method according to claim 26 further comprising fabricating a hole transporting layer, said hole transporting layer disposed between said anode and said first emissive layer.
28. A method according to claim 25 further comprising fabricating a electron transporting layer, said electron transporting layer disposed over said third emissive layer.
29. A method according to claim 26 further comprising fabricating a cathode layer, said cathode layer disposed over said third emissive layer.
30. A method according to claim 28 further comprising a cathode layer, said cathode layer disposed over said electron transporting layer.
31. A method according to claim 25 wherein said first spectrum, said second spectrum and said third spectrum combine such that a combined output spectrum of said device is white.
32. A device according to claim 1 wherein the electron and hole mobilities of said emissive layers enable a large recombination zone for emission.
33. A method according to claim 25 wherein the electron and hole mobilities of said emissive layers enable a large recombination zone for emission.