Gated pixel elements using polymer electroluminescent materials for panel displays

• US 5,977,718 A
• Filed: 08/08/1997
• Issued: 11/02/1999
• Est. Priority Date: 08/08/1997
• Status: Expired due to Term

• Current Assignee: InnoLux Corporation
• Original Assignee: Alton O. Christensen
• Inventors: Christensen, Alton O.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): NGUYEN, HOANG V
• Application Number:
  US08/907,559
• Time in Patent Office: 816 Days
• Field of Search: 315/169.1, 315/169.3, 315/169.4, 313/503, 313/504, 257/40, 257/59
• US Class Current: 315/169.1
• CPC Class Codes: H10K 50/80 Constructional details
• CPC Class Codes: H10K 50/805 Electrodes
• CPC Class Codes: H10K 59/805 Electrodes
• CPC Class Codes: H10K 59/82 Interconnections, e.g. terminals H10K59/131, H10K59/179 take precedence

Abstract

A gated pixel device employing conjugated polymer electroluminescent material is disclosed. Pixel devices are triodes or diodes. Conjugated polymer electroluminescent material is spun onto a flexible, transparent substrate thereby reducing fabrication cost when compared to conventional material deposition techniques. A plurality of pixels can be integrally fabricated on a common, flexible, transparent substrate thereby producing a display panel which can be formed or shaped into any desired geometry, and thereby creating applications not possible with conventional, rigid flat panel displays in the prior art. Both monocolor and full color flexible display panels are disclosed.

Claims

1. An integrally fabricated gated pixel element affixed to an optically transparent substrate wherein said pixel element comprises:

(a) conjugated polymer electroluminescent material;

(b) an injector electrode in ohmic contact with said conjugated polymer electroluminescent material;

(c) a collector electrode in ohmic contact with said electroluminescent material;

(d) a gate interconnect to enable a control gate signal to be applied to said pixel; and

(e) a gate electrode in contact with said gate interconnect and separated from said conjugated polymer electroluminescent material by dielectric material.

2. The pixel element of claim 1 wherein:

(a) said substrate is flexible, and

(b) said conjugated polymer electroluminescent material is deposited as a flexible layer upon said substrate.

3. The pixel element of claim 1 wherein said injector electrode and said collector electrode comprise Li₃ Al₂.

4. The pixel element of claim 1 wherein said injector electrode comprises Li₃ Al₂ and said collector electrode comprises Cr₃ Si.

5. The pixel element of claim 1 wherein said conjugated polymer electroluminescent material comprises polyflourine with two benzene rings with alkyl chains.

6. The pixel element of claim 1 wherein said conjugated polymer electroluminescent material comprises MEH-PPV.

7. The pixel element of claim 1 wherein said conjugated polymer electroluminescent material comprises PPV.

8. The pixel element of claim 1 wherein said substrate comprises polyethylene terephthalate.

9. An integrally fabricated diode pixel element affixed to an optically transparent substrate wherein said pixel element comprises:

(a) conjugated polymer electroluminescent material;

(b) an injector electrode in ohmic contact with said conjugated electroluminescent material; and

(c) a collector electrode in ohmic contact with said electroluminescent material.

10. The pixel element of claim 9 wherein:

(a) said collector electrode comprises Cr₃ Si; and

(b) said injector electrode comprises Li₃ Al₂.

11. The pixel element of claim 9 wherein conjugated polymer electroluminescent material comprises PPV.

12. The pixel element of claim 9 wherein said substrate comprises polyethylene terephthalate.

13. An integrally fabricated gated pixel element in a display of plural pixel elements affixed to a common optically transparent substrate wherein said pixel element comprises:

(a) conjugated polymer electroluminescent material;

(b) an injector electrode in ohmic contact with said conjugated polymer electroluminescent material;

(c) a collector electrode in ohmic contact with said conjugated polymer electroluminescent material;

(d) a gate interconnect to enable a control gate signal to be applied to said pixel; and

(e) a gate electrode in contact with said gate interconnect and separated from said conjugated polymer electroluminescent material by a thin layer of dielectric material.

14. The apparatus of claim 13 wherein said electroluminescent material is selected to emit photons in a desired region of the visible spectrum, and said electroluminescent material is organic.

15. The apparatus of claim 13 wherein said injector electrode is Li₃ Al₂.

16. The apparatus of claim 15 wherein said collector electrode is Li₃ Al₂.

17. The apparatus of claim 15 wherein said collector electrode is Cr₃ Si.

18. The apparatus of claim 13 wherein:

(a) said gate electrode comprises a high work function; and

(b) said gate electrode is selected from the group of Al, Cu, metal silicide or doped polycrystalline silicon.

19. The apparatus of claim 18 wherein said control gate signal comprises a variable potential applied to said gate electrode by said gate interconnect thereby changing said conjugated polymer electroluminescent material from a conducting region to a nonconducting depletion region or causes avalanche of carriers between said injector and collector electrode, thereby controlling brightness of photon emission from said conjugated polymer electroluminescent material.

20. The apparatus of claim 13 wherein said conjugated polymer electroluminescent material produces red, green or blue electroluminescence.

21. The apparatus of claim 13 wherein said conjugated polymer electroluminescent material comprises polyflourine with two benzene rings with alkyl chains.

22. The apparatus of claim 13 wherein said conjugated polymer electroluminescent material comprises MEH-PPV.

23. The apparatus of claim 13 wherein conjugated polymer electroluminescent material PPV.

24. The apparatus of claim 13 wherein said substrate comprises a flexible film.

25. The apparatus of claim 24 wherein said flexible film comprises polyethylene terephthalate.

26. An flexible, integrally fabricated, gated control element in a display on a flexible, supportive substrate wherein said element comprises:

(a) a current controlled material;

(b) an injector electrode of Li₃ Al₂ in ohmic contact with said current controlled material;

(c) a collector electrode in ohmic contact with said current controlled material;

(d) a gate interconnect to provide a control gate signal; and

(e) a gate electrode in contact with said gate interconnect to control current flow to said current controlled material.

27. The apparatus of claim 26 wherein said gate electrode is separated from said current controlled material by a layer of dielectric;

and said current controlled material is conjugated polymer electroluminescent material.

28. The apparatus of claim 27 wherein:

(a) said conjugated polymer electroluminescent material is organic;

(b) said collector is Cr₃ Si; and

(c) said supportive substrate is transparent.

29. The apparatus of claim 28 wherein said substrate comprises polyethylene terephthalate.

30. The apparatus of claim 28 wherein said gate electrode is a high work function material and said gate interconnect is aluminum or an alloy thereof and further includes dielectric encapsulating material around said gated control element.

31. The apparatus of claim 26 wherein said current control material produces red, green or blue electroluminescence.

32. The apparatus of claim 31 wherein said current control material comprises polyflourine with two benzene rings with alkyl chains.

33. The apparatus of claim 31 wherein said current control material comprises MEH-PPV.

34. The apparatus of claim 31 wherein said current control material comprises PPV.

35. A method for operating a flexible display matrix integrated circuit element comprising the steps of:

(a) forming a triode element comprising an injector and a collector electrode in ohmic contact with a current controlled material, and further comprising a gate electrode in separated from said current controlled material by a thin layer of dielectric material;

(b) creating and modulating the extent of a depletion region within said current controlled material in the vicinity of said gate electrode by varying the potential of said gate electrode;

(c) applying a voltage potential across said injector and collector electrodes;

(d) changing the potential of said gate electrode until avalanche occurs within said current controlled material between said injector and said collector electrodes; and

(e) changing the integrated circuit conditions resulting from said avalanche condition.

36. The method of claim 35 wherein said triode forming step comprises the additional steps of:

(a) providing a substrate comprising a flexible, transparent film; and

(b) spinning said current control material onto said substrate.

37. The method of claim 36 comprising the additional steps of:

(a) forming a plurality of said triode elements on a common said flexible substrate; and

(b) configuring said plurality of triode elements to form a panel display.

38. The method of claim 37 comprising the additional step of flexing said substrate to operate said display panel in a curved geometry.