Electrochemical light-emitting devices

• US 5,682,043 A
• Filed: 06/28/1994
• Issued: 10/28/1997
• Est. Priority Date: 06/28/1994
• Status: Expired due to Term

• Current Assignee: DuPont Displays Incorporated (Corteva, Inc.)
• Original Assignee: UNIAX Corp (Corteva, Inc.)
• Inventors: Klavetter, Floyd L., Pei, Qibing
• Primary Examiner(s): Crane, Sara W.
• Application Number:
  US08/268,763
• Time in Patent Office: 1,218 Days
• Field of Search: 257/102, 257/103, 257/40, 313/498, 313/504
• US Class Current: 257/40
• CPC Class Codes: F21K 2/08 activated by an electric field, i.e. electrochemiluminescence
• CPC Class Codes: H10K 50/135 comprising mobile ions

Abstract

Electrochemical light emitting devices are disclosed which include a composite material in contact with two electrodes. The composite material is an admixture of ionic species and an `immobile` semiconductor. The semiconductor is capable of supporting both p- and n-type carriers and having a doping profile which can be dynamically changed in a controlled fashion through reversible electrochemical oxidation and reduction. Devices having this structure may be used to generate electrochemically induced p-n junctions, thereby providing a new means of exploiting the light emitting properties of such junctions under an applied voltage. Systems and methods for generating useful levels of light employing these devices are also disclosed.

Claims

1. An electrochemical light emitting device comprising a pair of contact layers held in a spaced relationship to one another by an admixed composite thin layer comprising immobile semiconductor and ionic species source.

2. The device of claim 1 wherein the semiconductor is an organic semiconductor.

3. The device of claim 2 wherein the admixed composite is in the form of an open connected network of organic semiconductor filled with the ionic species source.

4. The device of claim 2 wherein the organic semiconductor is a polymeric semiconductor.

5. The device of claim 4 wherein the polymeric semiconductor is a conjugated polymeric semiconductor.

6. The device of claim 4 wherein the polymeric semiconductor is a non-conjugated polymer comprising π

-conjugated moieties.

7. The device of claim 5 wherein the conjugated semiconductor comprises a homopolymer or copolymer having mer units selected from the group consisting of substituted and unsubstituted p-phenylene vinylene, substituted and unsubstituted p-phenylene, substituted and unsubstituted quinoline, substituted and unsubstituted p-phenylene-2,6-benzobisthiazole, substituted and unsubstituted p-phenylene-2,6-benzobisoxazole, substituted and unsubstituted p-phenylene-2,6-benzimidazole, substituted and unsubstituted arylene, and substituted and unsubstituted arylene vinylene, wherein arylene is naphthalene, anthracene, furylene, thienylene, pyrrole, oxadiazole, or isothianaphthene and mixtures thereof.

8. The device of claim 2 wherein the organic semiconductor comprises a conjugated semiconductor homooligomer or cooligomer having mer units selected from the group consisting of thiophene, phenylene, phenylene vinylene, pyrrole, acetylene, vinylene and derivatives and mixtures thereof.

9. The device of claim 2 wherein the organic semiconductor is a gel.

10. The device of claim 2 wherein the semiconductor is selected from laser dye and polymers and oligomers containing laser dye moieties.

11. The device of claim 1 wherein the ionic species source is admixed salt.

12. The device of claim 11 wherein the salt has a cation selected from the group consisting of the singly ionized alkali metals, lithium, sodium, potassium, rubidium, and cesium;

ions of the metals aluminum, silver, barium, calcium, cobalt, copper, chromium, zinc;

metallo-organic cations; and

organic cations such as ammonium, tetramethyl ammonium, tetraethyl ammonium, tetrapropyl ammonium, tetrabutyl ammonium, tetradecyl ammonium, tribenzyl ammonium, phenyl ammonium, and mixtures thereof and an anion selected from the group consisting of singly ionized halogens, fluorine, chlorine, bromine, and iodine;

inorganic anions such as perchlorate, bromate, nitrate, sulfate, phosphate, tetrafluoroborate, hexafluorophosphate, aluminum tetrachlorate; and

organic anions such as n-butyrate, trifluoromethane sulfonate, trifluoromethane sulfonamide, acetate, trifluoroacetate, tetraphenylborate, toluene sulfonate, dodecylbenzene sulfonate, camphor sulfonate, picrate, salicylate, thiocyanate, benzoate, and mixtures thereof.

13. The device of claim 1 wherein the ionic species source comprises polymeric electrolyte.

14. The device of claim 13 wherein the polymeric electrolyte itself comprises a mixture of electrolyte polymer and salt.

15. The device of claim 14 wherein the electrolyte polymer comprises a homopolymer or copolymer having mer units selected from the group consisting of ethylene oxide, propylene oxide, dimethyl siloxane, oxymethylene, epichlorohydran, phosphazene, bis-(methoxyethoxyethoxy)phosphazene, oxetane, tetrahydrofuran, 1,3-dioxolane, ethylene imine, ethylene succinate, ethylene sulfide, propylene sulfide, oligo(oxyethylene) methacrylate, oligo(oxyethylene) oxymethylene, oligo(oxyethylene) cyclotrisphosphazene and mixtures thereof.

16. The device of claim 13 wherein the polymeric electrolyte is a gel.

20. The device of claim 1 wherein the thin layer is from about 5 nm to about 10 um thick.

21. The device of claim 1 wherein the weight proportions of immobile semiconductor and ionic species source in the admixed composite thin layer range are from about 0.1:

0.9 to about 0.9;

0.1.

22. The device of claim 1 wherein at least one of the contact layers is substantially transparent at the wavelength at which the device emits light.

23. The device of claim 22 wherein both of the contact layers are substantially transparent at the wavelength at which the device emits light.

24. The device of claim 1 wherein at least one of the contact layers is selected from the group consisting of a layer comprising aluminum, silver, platinum, gold, palladium, tungsten, indium, zinc, copper, nickel, iron, lead, lead oxide, tin oxide, indium tin-oxide, graphite, doped silicon, doped germanium, doped gallium arsenide, doped polyaniline, doped polypyrrole, doped polythiophene, and derivatives and mixtures thereof.

25. The device of claim 24 wherein both of the contact layers are selected from the group consisting of a layer comprising aluminum, silver, platinum, gold, palladium, tungsten, indium, zinc, copper, nickel, iron, lead, lead oxide, tin oxide, indium tin-oxide, graphite, doped silicon, doped germanium, doped gallium arsenide, doped polyaniline, doped polypyrrole, doped polythiophene, and derivatives and mixtures thereof.

26. The device of claim 1 wherein one of the first and second contact layers is also in contact with a supporting substrate.

27. The device of claim 1 wherein both the first and second contact layers is also in contact with a supporting substrate.

28. The device of claim 1 wherein at least one of the first and second contact layers is also in contact with a supporting substrate selected from the group consisting of a free standing polymer film, either rigid or flexible, an inorganic material, an inorganic glass, amorphous silicon, an inorganic single crystal, single crystal silicon, single crystal quartz, single crystal sapphire, and a metal.

17. An electrochemical light emitting device comprising a pair of contact layers held in a spaced relationship to one another by an admixed composite thin layer comprising immobile conjugated polymeric or oligomeric semiconductor and polymeric or oligomeric electrolyte ionic species source.

18. The device of claim 17 wherein the conjugated polymeric or oligomeric semiconductor comprises a homopolymer or copolymer having mer units selected from the group consisting of substituted and unsubstituted p-phenylene vinylene, substituted and unsubstituted p-phenylene, substituted and unsubstituted quinoline, substituted and unsubstituted p-phenylene-2,6-benzobisthiazole, substituted and unsubstituted p-phenylene-2,6-benzobisoxazole, substituted and unsubstituted p-phenylene-2,6-benzimidazole, substituted and unsubstituted arylene, and substituted and unsubstituted arylene vinylene, wherein arylene is naphthalene, anthracene, furylene, thienylene, pyrrole, oxadiazole, or isothianaphthene;

or a homooligomer or cooligomer having mer units selected from the group consisting of thiophene, phenylene, phenylene vinylene, pyrrole, acetylene, vinylene and derivatives and mixtures thereof.

19. The electrochemical light emitting device of claim 17 wherein the polymeric electrolyte ionic species source itself comprises electrolyte polymer which is a homopolymer or copolymer having mer units selected from the group consisting of ethylene oxide, propylene oxide, dimethyl siloxane, oxymethylene, epichlorohydran, phosphazene, bis-(methoxyethoxyethoxy)phosphazene, oxetane, tetrahydrofuran, 1,3-dioxolane, ethylene imine, ethylene succinate, ethylene sulfide, propylene sulfide, oligo(oxyethylene) methacrylate, oligo(oxyethylene) oxymethylene, oligo(oxyethylene) cyclotrisphosphazene and mixtures thereof;

admixed with salt.

29. The device of claim 17 wherein one of the first and second contact layers is also in contact with a supporting substrate.

30. The device of claim 17 wherein both the first and second contact layers is also in contact with a supporting substrate.

31. The device of claim 17 wherein at least one of the first and second contact layers is also in contact with a supporting substrate selected from the group consisting of a free standing polymer film, either rigid or flexible, an inorganic material, an inorganic glass, amorphous silicon, an inorganic single crystal, single crystal silicon, single crystal quartz, single crystal sapphire, and a metal.

32. An electrochemical light emitting device comprising a pair of contacts held in a spaced relationship to one another by a thin layer comprising a block or random copolymer containing segments which provide immobile semiconductor regions and segments which are an ionic species source.

33. A system for light emission comprising a power supply applying an effective powering voltage across a pair of anode and cathode contact layers held in a spaced relationship to one another by an admixed composite thin layer comprising immobile semiconductor and ionic species source, the effective powering voltage thereby reducing the immobile semiconductor at the cathode to form negatively charged excitations and oxidizing the immobile semiconductor at the anode to form positively charged excitations, said negatively charged excitations and positively charged excitations propagating in the thin layer under the influence of the applied voltage and combining to form charge carrier pairs which decay radiatively in the thin layer so that light is emitted from the layer.

34. The system of claim 33 wherein the powering voltage is between 0.1 and 110 volts.

35. The system of claim 33 wherein the thin layer is from about 5 nm to about 10 um thick, the admixed composite is an open connected network of immobile conjugated organic semiconductor filled with the ionic species source and the weight proportions of immobile conjugated organic semiconductor and ionic species source in the admixed composite thin layer range are from about 0.1:

0.9 to about 0.9;

0.1.

36. The system of claim 35 wherein the conjugated organic semiconductor is selected from the group consisting of homopolymers and copolymers having mer units selected from the group consisting of substituted and unsubstituted p-phenylene vinylene, substituted and unsubstituted p-phenylene, substituted and unsubstituted quinoline, substituted and unsubstituted p-phenylene-2,6-benzobisthiazole, substituted and unsubstituted p-phenylene-2,6-benzobisoxazole, substituted and unsubstituted p-phenylene-2,6-benzimidazole, substituted and unsubstituted arylene, and substituted and unsubstituted arylene vinylene, wherein arylene is naphthalene, anthracene, furylene, thienylene, pyrrole, oxadiazole, or isothianaphthene;

and homooligomers and cooligomers having mer units selected from the group consisting of thiophene, phenylene, phenylene vinylene, pyrrole, acetylene, vinylene and derivatives and mixtures thereof.

37. The system of claim 35 wherein the ionic species source is admixed salt.

38. The system of claim 37 wherein the salt has a cation selected from the group consisting of the singly ionized alkali metals, lithium, sodium, potassium, rubidium, and cesium;

ions of the metals aluminum, silver, barium, calcium, cobalt, copper, chromium, zinc;

metallo-organic cations; and

organic cations such as ammonium, tetramethyl ammonium, tetraethyl ammonium, tetrapropyl ammonium, tetrabutyl ammonium, tetradecyl ammonium, tribenzyl ammonium, phenyl ammonium, and mixtures thereof and an anion selected from the group consisting of singly ionized halogens, fluorine, chlorine, bromine, and iodine;

inorganic anions such as perchlorate, bromate, nitrate, sulfate, phosphate, tetrafluoroborate, hexafluorophosphate, aluminum tetrachlorate; and

organic anions such as n-butyrate, trifluoromethane sulfonate, trifluoromethane sulfonamide, acetate, trifluoroacetate, tetraphenylborate, toluene sulfonate, dodecylbenzene sulfonate, camphor sulfonate, picrate, salicylate, thiocyanate, benzoate, and mixtures thereof.

39. The system of claim 35 wherein the ionic species source comprises polymeric electrolyte.

40. The system of claim 39 wherein the polymeric electrolyte comprises a mixture of salt and an electrolyte polymer selected from homopolymers and copolymers having mer units selected from the group consisting of ethylene oxide, propylene oxide, dimethyl siloxane, oxymethylene, epichlorohydran, phosphazene, bis-(methoxyethoxyethoxy)phosphazene, oxetane, tetrahydrofuran, 1,3-dioxolane, ethylene imine, ethylene succinate, ethylene sulfide, propylene sulfide, oligo(oxyethylene) methacrylate, oligo(oxyethylene) oxymethylene, oligo(oxyethylene) cyclotrisphosphazene and mixtures thereof.

41. The system of claim 33 wherein at least one of the contact layers is substantially transparent at the wavelength at which the device emits light such that the light is emitted through the substantially transparent contact layer.

42. The system of claim 34 wherein the powering voltage is less than 5 volts.

43. The system of claim 33 characterized by being capable of emitting polarized visible light.

44. The system of claim 33 wherein the pair of anode and cathode contact layers held in a spaced relationship to one another by an admixed composite thin layer are together in the form of a film.

45. The system of claim 33 wherein the pair of anode and cathode contact layers held in a spaced relationship to one another by an admixed composite thin layer are together in the form of a filament.

46. A process for generating useful levels of light comprising

applying an effective powering voltage across a pair of anode and cathode contact layers held in a spaced relationship to one another by an admixed composite thin layer comprising immobile semiconductor and ionic species source, the effective powering voltage thereby reducing the immobile semiconductor at the cathode to form negatively charged excitations and oxidizing the immobile semiconductor at the anode to form positively charged excitations, said negatively charged excitations and positively charged excitations migrating in the thin layer under the influence of the applied voltage and combining to form charge carrier pairs which decay radiatively in the thin layer so that light is emitted from the layer and

using the emitted light.

47. The process of claim 46 wherein the powering voltage is between 2 and 10 volts.

48. The process of claim 46 wherein the thin layer is from about 5 nm to about 10 um thick, the admixed composite is an open connected network of immobile conjugated organic semiconductor filled with the ionic species source and the weight proportions of immobile conjugated organic semiconductor and ionic species source in the admixed composite thin layer range are from about 0.1:

0.9 to about 0.9;

0.1.

49. The process of claim 48 wherein the conjugated organic semiconductor is selected from the group consisting of homopolymers and copolymers having mer units selected from the group consisting of substituted and unsubstituted p-phenylene vinylene, substituted and unsubstituted p-phenylene, substituted and unsubstituted quinoline, substituted and unsubstituted p-phenylene-2,6-benzobisthiazole, substituted and unsubstituted p-phenylene-2,6-benzobisoxazole, substituted and unsubstituted p-phenylene-2,6-benzimidazole, substituted and unsubstituted arylene, and substituted and unsubstituted arylene vinylene, wherein arylene is naphthalene, anthracene, furylene, thienylene, pyrrole, oxadiazole, or isothianaphthene;

and homooligomers and cooligomers having mer units selected from the group consisting of thiophene, phenylene, phenylene vinylene, pyrrole, acetylene, vinylene and derivatives and mixtures thereof.

50. The process of claim 48 wherein the ionic species source is admixed salt.

51. The process of claim 50 wherein the salt has a cation selected from the group consisting of the singly ionized alkali metals, lithium, sodium, potassium, rubidium, and cesium;

ions of the metals aluminum, silver, barium, calcium, cobalt, copper, chromium, zinc;

metallo-organic cations; and

organic cations such as ammonium, tetramethyl ammonium, tetraethyl ammonium, tetrapropyl ammonium, tetrabutyl ammonium, tetradecyl ammonium, tribenzyl ammonium, phenyl ammonium, and mixtures thereof and an anion selected from the group consisting of singly ionized halogens, fluorine, chlorine, bromine, and iodine;

inorganic anions such as perchlorate, bromate, nitrate, sulfate, phosphate, tetrafluoroborate, hexafluorophosphate, aluminum tetrachlorate; and

organic anions such as n-butyrate, trifluoromethane sulfonate, trifluoromethane sulfonamide, acetate, trifluoroacetate, tetraphenylborate, toluene sulfonate, dodecylbenzene sulfonate, camphor sulfonate, picrate, salicylate, thiocyanate, benzoate, and mixtures thereof.

52. The process of claim 48 wherein the ionic species source comprises polymeric electrolyte.

53. The process of claim 52 wherein the polymeric electrolyte itself comprises a mixture of salt and an electrolyte polymer selected from homopolymers and copolymers having mer units selected from the group consisting of ethylene oxide, propylene oxide, dimethyl siloxane, oxymethylene, epichlorohydran, phosphazene, bis-(methoxyethoxyethoxy)phosphazene, oxetane, tetrahydrofuran, 1,3-dioxolane, ethylene imine, ethylene succinate, ethylene sulfide, propylene sulfide, oligo(oxyethylene) methacrylate, oligo(oxyethylene) oxymethylene, oligo(oxyethylene) cyclotrisphosphazene and mixtures thereof.

54. The process of claim 48 wherein at least one of the contact layers is substantially transparent at the wavelength at which the device emits light such that the light is emitted through the substantially transparent contact layer.

55. The process of claim 48 wherein the powering voltage is less than 5 volts.

56. The process of claim 48 characterized by being capable of emitting polarized visible light.

57. The process of claim 48 wherein the pair of anode and cathode contact layers held in a spaced relationship to one another by an admixed composite thin layer are together in the form of a film.

58. The process of claim 48 wherein the pair of anode and cathode contact layers held in a spaced relationship to one another by an admixed composite thin layer are together in the form of a filament.