Integrated fuses for OLED lighting device
View Patent ↗An embodiment of the present invention pertains to an electroluminescent lighting device for area illumination. The lighting device is fault tolerant due, in part, to the patterning of one or both of the electrodes into strips, and each of one or more of these strips has a fuse formed on it. The fuses are integrated on the substrate. By using the integrated fuses, the number of external contacts that are used is minimized. The fuse material is deposited using one of the deposition techniques that is used to deposit the thin layers of the electroluminescent lighting device.
1. A fault-tolerant electroluminescent lighting device, comprising:
a substrate;
a first electrode on said substrate;
a thin-film stack on said first electrode, wherein said thin-film stack includes an electroluminescent layer;
a second electrode on said thin-film stack,
wherein a particular one of either said first electrode or said second electrode is a plurality of electrode strips, a particular one of said plurality of electrode strips has at least one gap that separates said particular electrode strip into a plurality of electrode segments, and a fuse material at least partially covers a particular one of said at least one gap such that two adjacent electrode segments that are separated by said particular gap are electrically connected to each other, and resistivity of said fuse material increases when a large current flows through said fuse material, and
wherein said at least one gap is on said substrate, and at least two of said plurality of electrode strips are coupled to a common external contact.
2. The device of claim 1 wherein said fuse material's resistivity increases when the large current flows due to redistribution of ionic charges within said fuse material that produces an internal electric field that compensates for an external electric field produced by the high current flow.
3. The device of claim 1 wherein said fuse material's resistivity increases when a large current flows due to the bulk of said fuse material increasing resistivity when said large current flows.
4. The device of claim 3 wherein said fuse material whose bulk increases resistivity when high current flows is: (1) a blend of polymers or (2) a blend of polymers and small molecules.
5. The device of claim 4 wherein said blend of polymers phase separate when a temperature of said blend increases above said polymers glass transition temperature.
6. The device of claim 1 wherein said fuse material is any one of: (1) PEDOT:PSS; (2) polycarbonate and polyaniline (“PANI”); (3) polymethylmethacrylate (“PMMA”) and PANI; (4) polycarbonate and carbon fibers; (5) PMMA and carbon fibers; (6) polycarbonate and triphenyldiamine (“TPD”); (7) polycarbonate and naphthylphenyldiamine (“NPD”); (8) polycarbonate and tris(8-hydroxyquinolinato)aluminum (“Alq”); (9) PMMA and TPD; (10) PMMA and NPD; or (11) PMMA and Alq.
7. The device of claim 1 further comprising a bank structure on said particular electrode, said bank structure includes a plurality of apertures, wherein a particular one of said plurality of apertures exposes said particular one of said at least one gap.
8. The device of claim 1 wherein a width of said particular one of said at least one gap is substantially smaller than a distance between two adjacent electrode strips.
9. The device of claim 1 wherein said fuse material is on said substrate.
10. The device of claim 1 wherein said other electrode that is not said particular electrode is a common continuous electrode.
11. The device of claim 1 wherein said other electrode that is not said particular electrode is a plurality of other electrode strips, said plurality of other electrode strips are parallel and aligned in the same direction as said plurality of electrode strips.
12. The device of claim 1 wherein said fault-tolerant electroluminescent lighting device is a fault-tolerant OLED lighting device.
13. A method to fabricate a fault-tolerant electroluminescent lighting device, comprising:
forming a first electrode on a substrate;
forming a thin-film stack on said first electrode, wherein said stack includes at least one layer and a particular one of said at least one layer is an electroluminescent layer; and
forming a second electrode on said thin-film stack,
wherein forming a particular one of either said first electrode or said second electrode includes:
patterning said particular electrode into a plurality of electrode strips, and further patterning at least one gap on a particular one of said plurality of electrode strips so as to separate said particular electrode strip into a plurality of electrode segments, wherein said at least one gap is on said substrate; and
depositing a fuse material over a particular one of said at least one gap to electrically connect two electrode segments that are adjacent to and separated by said particular gap, wherein resistivity of said fuse material increases when a large current flows through said fuse material, and
further comprising coupling at least two of said plurality of electrode strips to a common external contact.
14. The method of claim 13 wherein forming said thin-film stack includes depositing a particular one of said at least one layer using a particular deposition technique, and said particular deposition technique is also used to deposit said fuse material.
15. The method of claim 13 further comprising forming a bank structure on said particular electrode, said bank structure includes a plurality of apertures, wherein a particular one of said plurality of apertures exposes said particular one of said at least one gap.
16. The method of claim 13 wherein said fuse material is selectively deposited.
17. The method of claim 16 wherein said fuse material is selectively deposited using any of the following techniques: ink-jet printing, screen printing, flex printing, or shadow masking.
18. The method of claim 13 wherein said fuse material is nonselectively deposited.
19. The method of claim 18 wherein said fuse material is nonselectively deposited using any of the following techniques: evaporation, sputtering chemical vapor deposition, spin coating, web coating, or spray coating.
20. The method of claim 18 wherein if said fuse material is nonselectively deposited, then a width of said particular one of said at least one gap is substantially smaller than a distance between two adjacent electrode strips.
21. The method of claim 13 wherein said fuse material is any one of: (1) PEDOT:PSS; (2) polycarbonate and polyaniline (“PANI”); (3) polymethylmethacrylate (“PMMA”) and PANI; (4) polycarbonate and carbon fibers; (5) PMMA and carbon fibers; (6) polycarbonate and triphenyldiamine (“TPD”); (7) polycarbonate and naphthylphenyldiamine (“NPD”); (8) polycarbonate and tris(8-hydroxyquinolinato)aluminum (“Alq”); (9) PMMA and TPD; (10) PMMA and NPD; or (11) PMMA and Alq.
22. The method of claim 13 wherein said other electrode that is not said particular electrode is a common continuous electrode.
23. The method of claim 13 wherein forming said other electrode that is not said particular electrode includes
patterning said other electrode into a plurality of other electrode strips, wherein said plurality of other electrode strips are parallel and aligned in the same direction as said plurality of electrode strips.
24. A fault-tolerant electroluminescent lighting device produced according to the method of claim 13 .
25. A fault-tolerant OLED lighting device produced according to the method of claim 13 .
26. A method to operate a fault-tolerant electroluminescent lighting device, wherein said lighting device includes an electrode that is patterned into a plurality of electrode strips and a particular one of said plurality of electrode strips includes a gap that separates said particular electrode strip into a first electrode segment and a second electrode segment, wherein a fuse material at least partially covers said gap such that said first electrode segment is electrically connected to said second electrode segment, the method comprising:
driving a current across said fuse material; and
if the current driven across said fuse material is high, then increasing resistivity of said fuse material so that current flow across said fuse material is decreased.
27. The method of claim 26 wherein said resistivity of said fuse material is increased when current flow is high across said fuse material by redistributing ionic charges within said fuse material to produce an internal electric field that compensates for an external electric field produced by the high current flow.
28. The method of claim 26 wherein said fuse material's resistivity increases when current flow is high due to the bulk of said fuse material increasing resistivity when said current flow is high.
29. The method of claim 28 wherein said fuse material is: (1) a blend of polymers or (2) a blend of polymers and small molecules.
30. The method of claim 29 wherein said blend of polymers phase separate when a temperature of said blend increases above said polymers' glass transition temperature.
31. The method of claim 26 wherein said fuse material is any one of: (1) PEDOT:PSS; (2) polycarbonate and polyaniline (“PANI”); (3) polymethylmethacrylate (“PMMA”) and PANI; (4) polycarbonate and carbon fibers; (5) PMMA and carbon fibers; (6) polycarbonate and triphenyldiamine (“TPD”); (7) polycarbonate and naphthylphenyldiamine (“NPD”); (8) polycarbonate and tris(8-hydroxyquinolinato)aluminum (“Alq”); (9) PMMA and TPD; (10) PMMA and NPD; or (11) PMMA and Alq.