ORGANIC LIGHT EMITTING DEVICES

• US 20010014391A1
• Filed: 12/09/1999
• Published: 08/16/2001
• Est. Priority Date: 12/13/1994
• Status: Active Grant

• Current Assignee: Dennis Matthew Mccarty, Linda Susan Sapochak, Mark Edward Thompson, Paul Edward Burrows, Stephen Ross Forrest
• Original Assignee: Dennis Matthew Mccarty, Linda Susan Sapochak, Mark Edward Thompson, Paul Edward Burrows, Stephen Ross Forrest
• Inventors: BURROWS, PAUL EDWARD, SAPOCHAK, LINDA SUSAN, MCCARTY, DENNIS MATTHEW, THOMPSON, MARK EDWARD, FORREST, STEPHEN ROSS
• Granted Patent: US 6,365,270 B2
• Time in Patent Office: Days
• US Class Current: 428/336
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: H01L 24/82 by forming build-up interconnects at chip-level, e.g. for high density interconnects [HDI] interconnection structure between a plurality of semiconductor chips H01L23/5389
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/12033 Gunn diode
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/12042 LASER
• CPC Class Codes: H01L 2924/12044 OLED
• CPC Class Codes: H10K 2102/3031 Two-side emission, e.g. transparent OLEDs [TOLED]
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 50/14 Carrier transporting layers
• CPC Class Codes: H10K 50/828 Transparent cathodes, e.g. comprising thin metal layers
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 85/10 Organic polymers or oligomers
• CPC Class Codes: H10K 85/111 comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
• CPC Class Codes: H10K 85/113 Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
• CPC Class Codes: H10K 85/114 Poly-phenylenevinylene; Derivatives thereof
• CPC Class Codes: H10K 85/146 poly N-vinylcarbazol; Derivatives thereof
• CPC Class Codes: H10K 85/30 Coordination compounds
• CPC Class Codes: H10K 85/322 : comprising boron
• CPC Class Codes: H10K 85/324 : comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/341 : Transition metal complexes, e.g. Ru(II)polypyridine complexes H10K85/331 takes precedence
• CPC Class Codes: H10K 85/60 : Organic compounds having low molecular weight H10K85/10 - H10K85/50 take precedence
• CPC Class Codes: H10K 85/611 : Charge transfer complexes
• CPC Class Codes: H10K 85/631 : Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
• CPC Class Codes: Y10T 428/26 : Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/265 : 1 mil or less
• CPC Class Codes: Y10T 428/31678 : Of metal

Abstract

A multicolor organic light emitting device employs vertically stacked layers of double heterostructure devices which are fabricated from organic compounds. The vertical stacked structure is formed on a glass base having a transparent coating of ITO or similar metal to provide a substrate. Deposited on the substrate is the vertical stacked arrangement of three double heterostructure devices, each fabricated from a suitable organic material. Stacking is implemented such that the double heterostructure with the longest wavelength is on the top of the stack. This constitutes the device emitting red light on the top with the device having the shortest wavelength, namely, the device emitting blue light, on the bottom of the stack. Located between the red and blue device structures is the green device structure. The devices are configured as stacked to provide a staircase profile whereby each device is separated from the other by a thin transparent conductive contact layer to enable light emanating from each of the devices to pass through the semitransparent contacts and through the lower device structures while further enabling each of the devices to receive a selective bias.

Claims

1. A multicolor light emitting device (LED) structure, comprising:

a plurality of at least a first and a second light emitting organic device (LED) stacked one upon the other, to form a layered structure, with each LED separated one from the other by a transparent conductive layer to enable each device to receive a separate bias potential to operate to emit light through the stack.

2. The multicolor light emitting device structure of

claim 1

, wherein each of said LED'"'"'s emits a different wavelength of light and therefore a different color when biased.

3. The multicolor light emitting device structure of

claim 1

, including at least first through third light emitting devices stacked upon one another, respectively.

4. The multicolor light emitting diode structure of

claim 3

, wherein said first device emits the color blue (B), said second device emits the color green (G) and third device emits the color red (R).

5. The multicolor light emitting device structure of

claim 4

, wherein said devices are stacked in the following sequence along the vertical axis starting from a bottom point and directed upward, wherein the first device emits a blue color, and has the second device for emitting a green color located on top of the upper surface of said blue emitting device, with the third device for emitting a red color located on top of the upper surface of said green emitting device, whereby said blue emitting device of the shortest wavelength is at the bottom with the red emitting device of the longest wavelength on top when the structure is aligned vertically.

6. The multicolor light emitting device structure of

claim 1

, wherein each LED device is a transparent double heterostructure (DH) device fabricated from organic materials.

7. The multicolor light emitting device structure of

claim 1

, wherein each LED device is a transparent single heterostructure device fabricated from organic materials.

8. The multicolor light emitting device structure of

claim 6

, wherein said transparent conductive layer includes indium tin oxide (ITO).

9. The multicolor light emitting device structure of

claim 7

, wherein said transparent conductive layer includes indium tin oxide (ITO).

10. The multicolor light emitting device structure of

claim 3

, wherein said at least first, second, and third organic LED'"'"'s are stacked in successive order over a common substrate.

11. The multicolor light emitting device structure of

claim 10

, wherein said substrate is at the bottom of said LED structure, and a topmost layer of said third organic LED included consists of indium tin oxide (ITO) material serving as a contact for an underlying metal material layer.

12. The multicolor light emitting device structure of

claim 6

, wherein said transparent conductive layer comprises a metallic layer having a work function less than about four electron volts, and an ITO layer on said metallic layer.

13. The multicolor light emitting device structure of

claim 6

, wherein said organic material is selected from the group consisting of trivalent metal quinolate complexes, trivalent metal bridged quinolate complexes, Schiff base divalent metal complexes, tin (iv) metal complexes, metal acetylacetonate complexes, metal bidentate ligand complexes, bisphosphonates, divalent metal maleonitriledithiolate complexes, molecular charge transfer complexes, aromatic and heterocyclic polymers and rare earth mixed chelates.

14. The multicolor light emitting device structure of

claim 13

wherein the trivalent metal quinolate complexes have the following formula.

wherein R is selected from the group consisting of hydrogen, substituted and unsubstituted alkyl, aryl and a heterocyclic group, L represents a ligand selected from the group consisting of picolylmethylketone;

substituted and unsubstituted salicylaldehyde;

a group of the formula R(O)CO—

wherein R is as defined above;

halogen;

a group of the formula RO—

wherein R is as defined above; and

quinolates and derivatives thereof.

15. The multicolor light emitting device structure of

claim 13

wherein the metal bidentate ligand complexes have the following formula:

MDL⁴₂

wherein M is selected from trivalent metals of Groups 3-13 of the Periodic Table and the Lanthanides, D is a bidentate ligand and L⁴ is selected from the group consisting of acetylacetonate;

compounds of the formula OR³R wherein R³ is Si or C and R is selected from the group consisting of hydrogen, substituted and unsubstituted alkyl, aryl, a heterocyclic group;

3,5-di(t-bu) phenol;

2,6-di(t-bu) phenol;

2,6-di(t-bu) cresol and a compound of the formula

16. The multicolor light emitting device structure of

claim 15

wherein D is selected from the group consisting of 2-picolylketones, 2-quinaldylketones and 2-(o-phenoxy) pyridineketones.

17. The multicolor light emitting device structure of

claim 13

wherein the Schiff base divalent metal complexes are selected from those having the formula

wherein M¹ is a divalent metal chosen from Groups 2-12 of the Periodic Table, R¹ is;

selected from the group consisting of

wherein X is selected from the group consisting of hydrogen, alkyl, alkoxy each having 1 to 8 carbon atoms, aryl, a heterocyclic group, phosphino, halogen and amine.

18. The multicolor light emitting device structure of

claim 13

wherein the aromatic and heterocyclic polymers are selected from the group consisting of poly (para-phenylene vinylene), poly (dialkoxyphenylene vinylene), poly (thiophene), poly (phenylene), poly (phenylacetylene) and poly (N-vinylcarbazole).

19. The multicolor light emitting device structure of

claim 13

wherein the rare earth mixed chelates comprise a Lanthanide bonded to a bidentate aromatic or heterocyclic group.

20. The multicolor light emitting device structure of

claim 19

wherein the bidentate aromatic or heterocyclic group is selected from the group consisting of salicylaldehydes and derivatives thereof, salicyclic acid, quinolates, Schiff base ligands, acetylacetonates, phenanthroline, bipyridine, quinoline and pyridine.

21. The multicolor light emitting device structure of

claim 19

wherein the divalent metal maleonitriledithiolate complexes have the formula

wherein M³ is a metal having a +2 charge, Y¹ is selected from the group consisting of cyano and substituted and unsubstituted phenyl, and L⁵ is a group having no charge.

22. The multicolor light emitting device structure of

claim 21

wherein L⁵ is a group of the formula P(OR)₃ or P(R)₃ wherein R is selected from the group consisting of hydrogen, substituted and unsubstituted alkyl, aryl and a heterocyclic group.

23. The multicolor light emitting device structure of

claim 13

wherein the bisphosphonates have the formula M²_x(O₃P-organic-PO₃)_y wherein M² is a metal ion and organic represents an aromatic or heterocyclic fluorescent compound bifunctionalized with phosphonate groups.

24. The multicolor light emitting device structure of

claim 13

wherein the trivalent metal bridged quinolate complexes have the formula

wherein M is a trivalent metal ion and Z is selected from SiR or P═

O wherein R is selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, aryl, or a heterocyclic group.

25. The multicolor light emitting device structure of

claim 13

wherein the tin (iv) metal complexes have the formula SnL¹₂L²₂ wherein L¹ is selected from the group consisting of salicylaldehydes, salicyclic acid, and quinolates and L² is selected from the group consisting of substituted and unsubstituted alkyl, aryl and a heterocyclic group.

26. The multicolor light emitting device structure of

claim 13

wherein the molecular charge transfer complexes comprise an electron acceptor complexed with an electron donor.

27. The multicolor light emitting device structure of

claim 1

, wherein said devices are stacked in an order dependent upon and in accordance with their respective emission wavelength and absorption characteristics.

28. The multicolor light emitting device of

claim 2

, wherein the longest wavelength LED is on top of the stack in the vertical direction followed by successively shorter wavelength LED'"'"'s, with the shortest wavelength LED on the bottom of the stack.

29. A multicolor light emitting device structure, comprising:

a transparent substrate layer having deposited on a surface a first transparent conductive coating;

a first light emitting device deposited on said first transparent conductive coating;

a second transparent conductive coating deposited on the surface of said first device not in contact with said first coating;

a second light emitting device deposited on the surface of said second coating;

a third transparent conductive coating deposited on the surface of said second device not in contact with said second coating;

a third light emitting device deposited on the surface of said third coating; and

a further conductive coating deposited on the surface of said third device not in contact with said third coating.

30. The multicolor light emitting device structure of

claim 29

, wherein said first, second, third and fourth conductive coatings are adapted to receive individual sources of biasing potential, respectively.

31. The multicolor light emitting device structure of

claim 29

, wherein said devices and conductive layers are deposited to form a staircase profile, with said transparent substrate being of a greater length than said first device, with said first device being of a greater length than said second device, with said second device of a greater length than said third device, wherein each step is covered by said respective conductive coating adapted for applying operating potentials to said device structures, and wherein said first through third transparent conductive coatings allow light emitted by any of said devices, respectively, to pass through said transparent substrate layer.

32. The multicolor light emitting device structure of

claim 29

, wherein said further conductive coating, includes a third metal that reflects upward directed light back to said substrate.

33. The multicolor light emitting device structure of

claim 32

, wherein said further conductive coating further includes a relatively thin indium tin oxide (ITO) layer between said thick metal and said surface of said third device not in contact with said third coating, said ITO layer serving as a contact for an underlying metal material layer of said third light emitting diode device.

34. The multicolor light emitting device structure of

claim 29

, wherein said transparent substrate is glass, said first conductive coating is indium tin oxide (ITO), and each of said second, third and further conductive coatings are comprised of an ITO layer disposed on a low work function metal layer.

35. The multicolor light emitting device structure of

claim 29

, wherein each of said devices are double heterostructures (DH), with said first device operative when biased to emit blue light (B), said second device operative when biased to emit green light (G), said third device operative when biased to emit red light (R).

36. The multicolor light emitting device structure of

claim 35

, wherein each DH structure is comprised of organic compounds.

37. The multicolor light emitting device structure of

claim 29

, wherein each of said devices are single heterostructures (SH), with said first device operative when biased to emit blue light (B), said second device operative when biased to emit green light (G), and said third device operative when biased to emit red light (R).

38. The multicolor light emitting device structure of

claim 29

, wherein each of said devices are polymer structures, with said first device operative when biased to emit blue light (B), said second device operative when biased to emit green light (G), and said third device operative when biased to emit red light (R).

39. A multicolor display, comprising:

a plurality of multicolor light emitting device pixel structures arranged in rows and columns to provide a display surface with each pixel structure consisting of at least one multicolor light emitting device structure wherein each device structure comprises first, second and third light emitting devices (LED'"'"'s) stacked one upon the other to form a layered structure, with each LED separated by a transparent conductive layer, and whereby said display can be biased via said conductive layers to cause said multicolor light emitting devices to emit light when biased.

40. The multicolor display of

claim 39

, wherein said first LED emits blue light (B), said second LED emits green light (G) and said third LED emits red light (R).

41. The multicolor display of

claim 39

, wherein each LED device is a double heterostructure (DH) device capable of emitting light as a function of an organic compound employed in said device.

42. The multicolor display of

claim 39

, wherein each of said LED devices is a single heterostructure (SH) device capable of emitting light as a function of an organic compound employed in said device.

43. The multicolor display of

claim 39

, wherein each of said LED devices is polymer structured device capable of emitting light as a function of an organic compound employed in said device.

44. The display of

claim 39

, wherein said plurality of multicolor device structures as arranged in rows and columns on a glass substrate coated with a thin transparent layer of ITO and with each of said first, second and third LED devices of each pixel stacked on said substrate to form a separate pixel location.

45. A method of fabricating a multicolor light emitting device (LED) structure comprising the steps of:

forming a first transparent conductive layer upon a transparent substrate;

depositing a first hole transporting layer upon said first transparent conductive layer;

depositing a first organic emission layer upon said first hole transporting layer to provide a first emission color;

depositing a first electron transporting layer upon said first emission layer;

depositing a second transparent conductive layer upon said first electron transporting layer, said second transparent conductive layer adapted to receive a first bias potential;

depositing a second hole transporting layer upon said second transparent conductive layer;

depositing a second organic emission layer upon said second hole transporting layer to provide a second emission color;

depositing a second electron transporting layer upon said second emission layer; and

depositing a third transparent conductive layer upon said second electron transporting layer, said third transparent conductive layer adapted to receive a second bias potential.

46. The method of

claim 45

, further including the step of shadow masking a region of said first transparent conductive layer prior to depositing said first hole transporting layer to expose said region of said first transparent conductive layer thereby enabling said first bias potential to be applied between said second transparent conductive layer and said region of said first transparent conductive layer.

47. The method of

claim 45

, further including the step of etching away a region of said first hole transporting layer to expose a portion of said first transparent conductive layer thereby enabling said first bias potential to be applied between said second transparent conductive layer and said exposed portion of said first transparent conductive layer.

48. A method of fabricating a hermetically packaged multicolor light emitting device (LED), comprising the steps of:

forming a first transparent conductive layer upon a transparent substrate;

masking said first conductive layer for depositing an SiO₂ layer thereupon in a concentric pattern;

forming on a portion of said first SiO₂ layer at least one multicolor LED, each including at least a first and a second organic light emitting devices (LED'"'"'s) stacked one upon the other to form a layered structure upon said first SiO₂ layer;

depositing via shadow masking a plurality of metal contacts or circuit paths each having one end terminating near an outer edge of said first SiO₂ layer, and each having another end terminating on an individual biasing electrode of said at least one multicolor LED;

depositing via shadow masking a second SiO₂ layer as a ring concentric with said first SiO₂ layer and over outer portions of said plurality of metal contacts but leaving exposed said one ends thereof;

depositing a ring of low temperature melting solder over and concentric with said second SiO₂ ring;

depositing on the bottom of a cover glass a metal ring positioned to be coincident with said ring of solder;

installing said cover glass over said substrate and at least one multicolor LED, with said ring of solder abutting against said metal ring on said cover glass;

placing said assembly in an inert gas atmosphere; and

heating said ring of solder to melt the solder for both forming an air tight seal, and entrapping said inert gas in an interior region between the bottom of said cover glass and underlying substrate.

49. The method of

claim 48

, wherein said multicolor LED forming step further includes forming a plurality of multicolor LED devices on said first SiO₂ layer.

50. The method of

claim 48

, wherein said inert gas includes dry nitrogen.

51. The method of

claim 48

, wherein said first transparent layer includes indium tin oxide (ITO).

52. The method of

claim 51

, further including the step of depositing a metal contact proximate an edge of and upon said ITO layer for serving as a cathode electrode.

53. The method of

claim 49

, further including the step of depositing a metal contact proximate an edge and upon said first transparent conductive layer for serving as a cathode electrode.

54. The method of

claim 53

, wherein said first transparent conductive layer includes indium tin oxide (ITO).

55. A multicolor, energizable, light emitting structure, comprising:

at least three layers of conductive material;

a transparent, energizable, light emitting device (LED) disposed between adjacent ones of said layers of conductive material, respectively, so that said LEDs are stacked on each other with one of said layers of conductive material disposed between each two of said LEDs and the other layers of conductive material are disposed on the outside of said LEDs;

said layers of conductive material disposed between adjacent ones of said LEDs and one of said outside layers being substantially transparent; and

means on each of said layers of conductive material for being connected to a bias for selectively energizing each of said LEDs.

56. The structure of

claim 55

, wherein each of said LEDs emits a different color.

57. The structure of

claim 56

, wherein said LEDs are stacked in a vertical array.

58. The structure of

claim 57

, further including:

a third LED in said stack;

the middle one of said LEDs being operative to emit light of a predetermined wavelength;

one of the other LEDs being operative to emit light of a longer wavelength; and

the lowest LED being operative to emit light of a shorter wavelength.

59. The structure of

claim 57

, further including:

a transparent substrate;

said stack of LEDs and layers of conductive material being supported by said transparent substrate in an order that corresponds to the length of the light wave that said LEDs emit; and

said LED emitting the shortest wavelength is closest to said transparent substrate so that the light emitted from each of said LEDs when it is energized is transmitted through the other LEDs and through said transparent substrate.

60. The structure of

claim 59

, further including:

a layer of anti-reflecting material disposed between said LED emitting the shortest wavelength and said transparent substrate so that the light emitted from each of said LEDs when it is energized is not reflected from said transparent substrate.

61. The structure of

claim 59

, further including:

a layer of reflective material adjacent said LED emitting the longest wavelength for reflecting light emitted from said LED back through said substrate.

62. The structure of

claim 55

, wherein said layer of conductive material includes indium-tin-oxide (ITO) and a metal.

63. The structure of

claim 62

, wherein said metal has a work function of less than four electron volts.

64. The structure of

claim 55

, further including:

a transparent substrate;

said stack of LEDs and layers of conductive material being supported by said transparent substrate in an order that corresponds to the length of the light wave that said LEDs emit; and

said LED emitting the shortest wavelength is closest to said transparent substrate so that the light emitted from each of said LEDs when it is energized is transmitted through the other LED and through said transparent substrate with substantially reduced absorption.

65. The structure of

claim 64

, further including:

a layer of anti-reflecting material disposed between said LED emitting the shortest wavelength and said transparent substrate so that the light emitted from each of said LEDs when it is energized is not reflected from said transparent substrate.

66. The structure of

claim 64

, wherein said layer of conductive material includes indium-tin-oxide (ITO) and a metal.

67. The structure of

claim 66

, wherein said metal has a work function of less than four electron volts.

68. The structure of

claim 64

, further including:

a layer of reflective material adjacent said LED emitting the longest wavelength for reflecting light emitted from said LED back through said substrate.

69. The structure of

claim 55

, wherein each of said LEDs is a double heterostructure.

70. The structure of

claim 55

, wherein each of said LEDs is a single heterostructure.

71. An energizable, light emitting structure, comprising:

a transparent substrate;

a first layer of substantially transparent, electrically conductive material supported on said substrate;

a transparent, energizable, light emitting device (LED) supported on said first layer of substantially transparent, electrically conductive material, said LED including an emission layer;

a second layer of electrically conductive material supported by said LED; and

said LED being operative to produce light and transmit it through said transparent substrate when energized.

72. The structure of

claim 71

, wherein said first and second layers comprise indium-tin-oxide.

73. The structure of

claim 72

, wherein said second layer further comprises a layer of metal that has a work function that is less than four electron volts.

74. The structure of

claim 73

, wherein said metal is from the group consisting of magnesium, arsenic and magnesium/gold alloy.

75. The structure of

claim 71

, further including:

said second layer of electrically conductive material being substantially transparent;

a second transparent, energizable, light emitting device (LED) supported on said second layer of electrically conductive material, said second LED including an emission layer;

a third layer of electrically conductive material supported by said second LED; and

said second LED being operative to produce light and transmit it through said first LED and through said transparent substrate when energized.

76. The energizable light emitting structure of

claim 71

, wherein said emission layer includes at least one material is selected from the group consisting of trivalent metal quinolate complexes, trivalent metal bridged quinolate complexes, Schiff base divalent metal complexes, tin (iv) metal complexes, metal acetylacetonate complexes, metal bidentate ligand complexes, bisphosphonates, divalent metal maleonitriledithiolate complexes, molecular charge transfer complexes, aromatic and heterocyclic polymers and rare earth mixed chelates.

77. A multicolor, energizable, light emitting display comprising:

a plurality of energizable, light emitting structures;

each of said structures comprising a plurality of transparent, light emitting devices (LED) that are stacked on each other;

each of said LEDs in each of said structures being operative to emit a different color light when energized; and

means for selectively energizing at least one of said LEDs in each of said structures so that the color produced by each of said light;

emitting structures is determined by which LED or LEDs in each light emitting structure is energized so that light emitted from said structures creates an image having a predetermined shape and color.

78. The display of

claim 77

, wherein said energizable, light emitting structures are arranged in an array, said array including at least two axes, and each of said light emitting structures is at the intersection of at least two of said axes.

79. The display of

claim 78

, wherein said axes define a horizontal axis and a vertical axis.

80. The display of

claim 78

, wherein said means for selectively energizing at least one of said LEDs in each of said structures includes:

means for selecting the structures and the LEDs in those structures -to be energized; and

means for serially scanning each of said axes so that said means for selectively energizing at least one of said LEDs scans along said axes so that said selected ones of said LEDS at the intersection of said axes are serially energized to emit light so that said image and said colors are created serially.

81. The display of

claim 77

, wherein said means for selectively energizing at least one of said LEDs in each of said structures includes:

means for substantially serially energizing said LEDs that are in said structures so that said image and said colors are created serially by said structures.

82. The display of

claim 77

, wherein said for means for selectively energizing said LEDs is operative to simultaneously energize selected ones of said LEDs in selected ones of said structures so that said image and said colors are created simultaneously by said selected ones of said LEDs in said selected ones of said structures.

83. The display of

claim 77

, wherein each of said structures further includes:

a transparent substrate;

said LEDs each having a bottom and a top and defining a stack of LEDs having a bottom and a top, said stack being supported on said transparent substrate;

a first layer of substantially transparent, electrically conductive material, said first layer being disposed between said bottom LED and said transparent substrate;

at least one second layer of substantially transparent, electrically conductive material, said second layers being disposed between adjacent ones of said LEDs;

a first layer of electrically conductive material, said first layer being disposed adjacent the top of said top LED; and

means on each of said layers of electrically conductive material for being connected to a bias for selectively energizing each of said LEDs.

84. The display of

claim 83

, wherein each of said layers of substantially transparent, electrically conductive material and said layer of electrically conductive material includes a layer of indium-tin-oxide.

85. The display of

claim 83

, wherein each of said layers of substantially transparent, electrically conductive material, and said layer of electrically conductive material, includes a layer of metal and a layer of indium-tin-oxide.

86. The display of

claim 85

, wherein said metal has a work function of less than about four electron volts.

87. The display of

claim 83

, further including:

a layer of reflective material disposed on the layer of electrically conductive material adjacent the top of said top LED so that light from said LEDs is reflected through said transparent substrate by said layer of reflective material.

88. The display of

claim 87

, further including:

said stack of LEDs is supported by said transparent substrate in an order that corresponds to the wavelength of the light that said LEDs emit; and

said LED emitting the shortest wavelength is closest to said transparent substrate so that the light emitted from each of said LEDs when it is energized is transmitted through the other LEDs and through said transparent substrate.

89. The display of

claim 88

, further including a layer of anti-reflecting material disposed between said LED emitting the shortest wavelength and said transparent substrate so that the light emitted from each of said LEDs when it is energized is not reflected from said transparent substrate.

90. The display of

claim 77

, further including:

a transparent substrate;

each of said LEDs having a top and a bottom;

at least two layers of substantially transparent, electrically conductive material, one of said layers being disposed on said transparent substrate;

the bottom of one of said LEDs in each of said structures being supported on said one layer of substantially transparent, electrically conductive material;

the others of said layers of substantially transparent, electrically conductive material being disposed between the remainder of said LEDs so that said LEDs define a stack;

a layer of electrically conductive material supported on the top of said LED in said stack that is furthest from said transparent substrate; and

means on each of said layers of substantially transparent, electrically conductive material and on said layer electrically conductive material for being connected to a bias for selectively energizing each of said LEDs.

91. The display of

claim 90

, wherein each of said layers of substantially transparent, electrically conductive material, and said layer of electrically conductive material include a layer of indium-tin-oxide.

92. The display of

claim 90

, wherein said layers of substantially transparent, electrically conductive material and each of said layers of electrically conductive material include a layer of metal and a layer of indium-tin-oxide.

93. The display of

claim 92

, wherein said metal has a work function of less than about four electron volts.

94. The display of

claim 90

, further including:

a layer of reflective material disposed on said layer of substantially transparent, electrically conductive material adjacent the top of said top LED so that light is reflected through said transparent substrate by said layer of reflective material.

95. The structure of

claim 94

, wherein

said stack of LEDs is supported by said transparent substrate in an order that corresponds to the wavelength of the light that said LEDs emit, and

said LED emitting the shortest wavelength is closest to said transparent substrate so that the light emitted from each of said LEDs when it is energized is transmitted through the other LEDs and through said transparent substrate.

96. The structure of

claim 95

, further including:

a layer of anti-reflecting material disposed between said LED emitting the shortest wavelength and said transparent substrate so that the light emitted from each of said LEDs when it is energized is not reflected from said transparent substrate.

97. The display of

claim 77

, wherein said plurality of LED'"'"'s include:

three LEDs;

each of said LEDs being a double heterostructure (DH);

said LED closest to said transparent substrate being operative when energized to emit blue light;

said LED furthest from said transparent substrate being operative when energized to emit red light; and

said other LED being operative when energized to emit green light.

98. The multicolor light emitting display of

claim 97

, wherein each of said LEDs includes an emission layer containing an organic material selected from the group consisting of trivalent metal quinolate complexes, trivalent metal bridged quinolate complexes, Schiff base divalent metal complexes, tin (iv) metal complexes, metal acetylacetonate complexes, metal bidentate ligand complexes, bisphosphonates, divalent metal maleonitriledithiolate complexes, molecular charge transfer complexes, aromatic and heterocyclic polymers and rare earth mixed chelates.

99. The display of

claim 77

, wherein said plurality of LED'"'"'s include:

three LEDs;

each of said LEDs being single heterostructures (SH);

said LED closest to said transparent substrate being operative when energized to emit blue light;

said LED furthest from said transparent substrate being operative when energized to emit red light; and

said other LED being operative when energized to emit green light.

100. The multicolor light emitting display of

claim 99

, wherein each of said LEDs includes an emission layer containing an organic material selected from the group consisting of trivalent metal quiniolate complexes, trivalent metal bridged quinolate complexes, Schiff base divalent metal complexes, tin (iv) metal complexes, metal acetylacetonate complexes, metal bidentate ligand complexes, bisphosphonates, divalent metal maleonitriledithiolate complexes, molecular charge transfer complexes, aromatic and heterocyclic polymers and rare earth mixed chelates.

101. A method of fabricating a multicolor, energizable light emitting structure, comprising the steps of:

providing a transparent substrate;

providing a first substantially transparent electrically conductive layer on said transparent substrate;

providing a first transparent, light emitting diode (LED) on said substrate, said first LED being operable when energized to emit a light of a first predetermined wavelength;

providing a second substantially transparent, electrically conductive layer on said first LED;

providing a second transparent, light emitting diode (LED) on said second substantially transparent, electrically conductive layer, said second LED being operable when energized to emit a light of a second predetermined wavelength, that is longer than said first predetermined wavelength; and

an electrically conductive layer on said second (LED).

102. A method as in

claim 101

, wherein

said steps of providing said first and second LEDs comprises the steps of forming each of said LEDs by;

depositing a hole transporting layer on said first and second substantially transparent, electrically conductive layers;

depositing an emission layer on each of said hole transporting layers; and

depositing an electron transporting layer on each of said emission layers.

103. The method of

claim 102

, wherein each of said emission layers includes a material selected from the group consisting of trivalent metal quinolate complexes, trivalent metal bridged quinolate complexes, Schiff base divalent metal complexes, tin (iv) metal complexes, metal acetylacetonate complexes, metal bidentate ligand complexes, bisphosphonates, divalent metal maleon~itriledithiolate complexes, molecular charge transfer complexes, aromatic and heterocyclic polymers and rare earth mixed chelates.

104. A method as in

claim 103

, wherein each of said substantially transparent electrically conductive layers and said layer of electrically conductive layer are comprised of indium-tin-oxide.

105. A method as in

claim 102

, further including:

the step of providing a layer of substantially transparent metal between said LEDs; and

a layer of said substantially transparent electrically conductive material on each of said layers of substantially transparent metal.

106. A method as in

claim 105

, wherein said metal has a work function of less than about four electron volts.

107. A method as in

claim 105

, wherein said metal is from the group consisting of magnesium, arsenic and magnesium/gold alloy.

108. A method as in

claim 101

, wherein said layer of electrically conductive material has a reflective surface for reflecting light emitted from said LEDs through said transparent substrate.

109. A method as in

claim 101

, further including the step of:

providing an electrical contact on each of said layers of substantially transparent, electrically conductive material, and on said layer of electrically conductive material so that each of said layers can be connected to a source of bias potential.

110. A transparent energizable, light emitting device (LED), comprising:

an emission layer, a hole transporting layer and an electron transporting layer;

said emission layer being disposed between said hole transporting layer and said electron transporting layer;

a first layer of substantially transparent electrically conductive material, and a second layer of electrically conductive material, said first layer being on said hole transporting layer, said second layer being on said electron transporting layer; and

said emission layer consists of material selected from the group consisting of trivalent metal quinolate complexes, trivalent metal bridged quinolate complexes, Schiff base divalent metal complexes, tin (iv) metal complexes, metal acetylacetonate complexes, metal bidentate ligand complexes, bisphosphonates, divalent metal maleonitriledithiolate complexes, molecular charge transfer complexes, aromatic and heterocyclic polymers and rare earth mixed chelates.

111. The device of

claim 110

, wherein

said emission layer is no more than about 200 Å

thick;

said hole transporting layer is no more than about 1000 Å

thick; and

said electron transporting layer is no more than about 1000 Å

thick.