Electroluminescent cells

Patent metadata

Field	Value
Publication number	US-11696378-B2
Application number	US-202117450945-A
Country	US
Kind code	B2
Filing date	Oct 14, 2021
Priority date	Oct 14, 2021
Publication date	Jul 4, 2023
Grant date	Jul 4, 2023

Abstract

An electroluminescent cell can comprise a first electrode; a second electrode; and an electroluminescent layer disposed between the first electrode and the second electrode. The second electrode can comprise a light-transmitting electrode layer that can comprise electrically conductive regions interspersed by light-transmitting regions. The light-transmitting regions can have higher light-transmissivity than the electrically conductive regions.

First claim

The invention claimed is:

1. An electroluminescent cell, comprising:
a first electrode;
a second electrode; and
an electroluminescent layer disposed between the first electrode and the second electrode,
wherein the second electrode defines electrically conductive regions and light-transmitting regions interspersed among the electrically conductive regions with the electrically conductive regions formed from an electrophotographic composition including a thermoplastic polymer and an electrically conductive pigment, and wherein the light-transmitting regions have a higher light-transmissivity compared to the electrically conductive regions.

2. The electroluminescent cell as claimed in claim 1 , wherein the electrically conductive regions include a charge director, a charge adjuvant, or a combination thereof.

3. The electroluminescent cell as claimed in claim 1 , wherein a ratio of a total area of the light-transmitting regions to a total area of the electrically conductive regions is at least 30%.

4. The electroluminescent cell as claimed in claim 1 , wherein the light-transmitting regions are apertures.

5. The electroluminescent cell as claimed in claim 4 , wherein the electrically conductive regions define a reticulated network of electrically conductive pathways with the apertures defined between adjacent pathways.

6. The electroluminescent cell as claimed in claim 5 , wherein the reticulated network is a grid.

7. The electroluminescent cell as claimed in claim 5 , wherein each of the electrically conductive pathways is 60 μm to 200 μm wide with adjacent pathways spaced 200 μm to 1000 μm.

8. The electroluminescent cell as claimed in claim 1 , wherein the first electrode comprises the thermoplastic polymer and the electrically conductive pigment.

9. The electroluminescent cell as claimed in claim 1 , further comprising a light-transmitting layer of a conductive polymer in electrical contact with the second electrode.

10. The electroluminescent cell as claimed in claim 1 , further comprising a dielectric layer disposed between the electroluminescent layer and the first electrode.

11. The electroluminescent cell as claimed in claim 1 , wherein the second electrode abuts the electroluminescent layer.

12. The electroluminescent cell as claimed in claim 1 , wherein the electrically conductive regions are in direct contact with the electroluminescent layer.

13. The electroluminescent cell as claimed in claim 1 , wherein the light-transmitting regions are apertures extending through the second electrode and open to the electroluminescent layer.

14. The electroluminescent cell as claimed in claim 1 , wherein the electrically conductive pigment is present in an amount of from 50 wt % to 70 wt %, based on a total weight of the electrophotographic composition.

15. The electroluminescent cell as claimed in claim 1 , wherein the thermoplastic polymer is present in an amount of from 1 wt % to 15 wt %, based on a total weight of solids of the electrophotographic composition.

16. A method of making an electroluminescent cell, the method comprising:
forming a first electrode;
disposing an electroluminescent layer over the first electrode; and
forming a second electrode over the electroluminescent layer by electrophotographically printing an electrophotographic composition including a thermoplastic polymer and an electrically conductive pigment,
the second electrode defining electrically conductive regions that are formed from the electrophotographic composition, wherein light-transmitting regions are interspersed among the electrically conductive regions and the light-transmitting regions having a higher light-transmissivity compared to the electrically conductive regions.

17. The method as claimed in claim 16 , wherein the electroluminescent layer is disposed over the first electrode by electrophotographically printing the electrophotographic composition.

18. The method as claimed in claim 16 , wherein the first electrode is formed by electrophotographically printing the electrophotographic composition onto a print substrate.

Assignees

• Hewlett Packard Development Co

Inventors

• Farran Samer
• Grinwald Yaron

Classifications

• H05B33/28 Primary

  of translucent electrodes · CPC title

• G03G5/09

  Sensitisors or activators, e.g. dyestuffs (G03G5/12 takes precedence) · CPC title

• G03G13/00

  Electrographic processes using a charge pattern (G03G15/00, G03G16/00, G03G17/00 take precedence) · CPC title

• G03G5/0528

  Macromolecular bonding materials · CPC title

• G03G9/0926

  characterised by physical or chemical properties · CPC title