ELECTROLUMINESCENT DEVICE HAVING IMPROVED POWER DISTRIBUTION

• US 20080278063A1
• Filed: 05/07/2007
• Published: 11/13/2008
• Est. Priority Date: 05/07/2007
• Status: Abandoned Application

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Cok, Ronald S.
• Application Number:
  US11/744,950
• Publication Number:
  US 20080278063A1
• Time in Patent Office: Days
• US Class Current: 313/500
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: H05B 33/22 characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
• CPC Class Codes: H10K 2102/331 Nanoparticles used in non-emissive layers, e.g. in packaging layer
• CPC Class Codes: H10K 50/856 comprising reflective means
• CPC Class Codes: H10K 59/878 comprising reflective means

Abstract

An electroluminescent device comprising a first electrode and a second electrode having an EL unit formed there-between, wherein the EL unit comprises a light-emitting layer containing quantum dots, and the first and second electrodes define one or more light-emitting areas; wherein at least a portion of the second electrode is transparent and light emitted by the EL unit is viewed from a first side of the electroluminescent device that is nearer the second electrode; and one or more reflective elements that are electrically-conductive and are formed as part of the second electrode or in electrical communication with the second electrode; and wherein the reflective elements are located at least partially within the light emitting areas.

Claims

1. An electroluminescent device (EL), comprising:

a first electrode;

a second electrode having a first side and a second side, and wherein at least a portion of the second electrode is transparent;

one or more light-emitting areas that are defined by the first and second electrodes;

an EL unit comprising a light-emitting layer formed between the first electrode and the second electrode, and wherein the first side of the second electrode is adjacent to the EL unit and light that leaves the EL device exits the second side of the second electrode through the transparent portion; and

one or more reflective elements that are electrically-conductive and are formed as part of the second electrode or are in electrical communication with the second electrode; and

wherein the reflective elements are located at least partially within the one or more light emitting areas.

2. The electroluminescent device of claim 1, wherein the light-emitting layer is a polycrystalline inorganic light-emitting layer comprising core/shell quantum dots within an inorganic semiconductor matrix.

3. The electroluminescent device of claim 1, wherein the light-emitting layer is a hybrid light-emitting layer comprising core/shell quantum dots within an organic semiconductor matrix.

4. The electroluminescent device of claim 1, wherein the EL unit is comprised of organic materials.

5. The electroluminescent device of claim 1, wherein the second electrode includes multiple non-contiguous transparent portions.

6. The electroluminescent device of claim 1, wherein the reflective elements are thicker than the transparent portion of the second electrode.

7. The electroluminescent device of claim 1, wherein the second electrode comprises a transparent conductive layer and the transparent portion of the second electrode is defined by the reflective elements.

8. The electroluminescent device of claim 1, further comprising a substrate;

and a transparent cover provided adjacent to the second side of the second electrode.

9. The electroluminescent device of claim 8 wherein the EL unit and transparent portions of the second electrode have a first refractive index range, and wherein the electroluminescent device further comprises:

a light scattering layer located between the substrate and the cover for scattering light emitted by the light emitting layer, wherein the cover has a second refractive index; and

transparent gaps between the second electrode and the cover, wherein the reflective elements physically space the cover from the second electrode creating said transparent gaps, and wherein the transparent gaps have a third refractive index lower than each of the first refractive index range and the second refractive index.

10. The electroluminescent device of claim 1, further comprising a substrate, wherein the substrate is transparent and is adjacent to the second side of the second electrode.

11. The electroluminescent device of claim 1 further comprising a transparent insulator layer formed adjacent to the second electrode opposite the EL unit and between the second electrode and the reflective elements.

12. The electroluminescent device of claim 11, further comprising a transparent substrate adjacent to the second side of the second electrode, and wherein the first electrode is reflective.

13. The electroluminescent device of claim 11, further comprising a substrate adjacent to a side of the first electrode opposite the EL unit.

14. The electroluminescent device of claim 11, wherein the reflective elements are electrically connected to the second electrode through a via in the transparent insulating layer.

15. The electroluminescent device of claim 7, wherein the transparent conductive layer is continuous and co-extensive with the light-emitting layer.

16. The electroluminescent device of claim 1, further comprising a scattering layer optically integrated with the first and second electrodes and the EL unit.

17. The electroluminescent device of claim 16, wherein the scattering layer is formed only in areas corresponding to the transparent portion of the second electrode.

18. The electroluminescent device of claim 16, wherein at least one of the first and second electrodes is a scattering electrode.

19. The electroluminescent device of claim 1, wherein the transparent portion of the second electrode is equal to or greater than one micron in at least one dimension.

20. The electroluminescent device of claim 1, further comprising color filters located in correspondence with the transparent portion of the second electrode.

21. The electroluminescent device of claim 1, comprising multiple light emitting areas and wherein the transparent portion of the second electrode are not aligned with the light emitting areas.

22. The electroluminescent device of claim 1, further comprising a transistor formed on a substrate and wherein the reflective elements are a conductive bus that is a signal or power bus connected to a terminal of the transistor.

23. The electroluminescent device of claim 1, wherein the reflective elements extend beyond the light-emitting areas.

24. The electroluminescent device of claim 1, wherein the reflective elements have two sides, a first side nearest the EL unit being reflective for reflecting emitted light and a second side opposite the first being light-absorbing for absorbing incident ambient light.