Method of Manufacturing a Printable Composition of a Liquid or Gel Suspension of Diodes

• US 20120164796A1
• Filed: 08/31/2011
• Published: 06/28/2012
• Est. Priority Date: 05/31/2007
• Status: Active Grant

• Current Assignee: NthDegree Technologies Worldwide Inc.
• Original Assignee: NthDegree Technologies Worldwide Inc.
• Inventors: Lowenthal, Mark David, Ray, William Johnstone, Shotton, Neil O., Blanchard, Richard A., Lewandowski, Mark Allan, Oraw, Brad, Baldridge, Jeffrey, Perozziello, Eric Anthony
• Granted Patent: US 8,852,467 B2
• Time in Patent Office: Days
• US Class Current: 438/127
• CPC Class Codes: H01L 21/6836 Wafer tapes, e.g. grinding or dicing support tapes adhesive tapes in general C09J7/20
• CPC Class Codes: H01L 24/95 at chip-level, i.e. with connecting carried out on a plurality of singulated devices, i.e. on diced chips
• 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 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/12042 LASER
• CPC Class Codes: H01L 2924/13033 TRIAC - Triode for Alternating Current - A bidirectional switching device containing two thyristor structures with common gate contact
• CPC Class Codes: H01L 2924/13034 Silicon Controlled Rectifier [SCR]
• CPC Class Codes: H01L 2924/1305 Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/1306 Field-effect transistor [FET]
• CPC Class Codes: H01L 2924/13062 Junction field-effect transistor [JFET]
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 31/022408 for devices characterised by at least one potential jump barrier or surface barrier
• CPC Class Codes: H01L 31/02363 of the semiconductor body itself, e.g. textured active layers
• CPC Class Codes: H01L 31/035281 Shape of the body
• CPC Class Codes: H01L 31/0475 PV cell arrays made by cells in a planar, e.g. repetitive, configuration on a single semiconductor substrate; PV cell microarrays PV modules composed of a plurality of thin film solar cells deposited on the same substrate H01L31/046
• CPC Class Codes: H01L 31/184 the active layers comprising only AIIIBV compounds, e.g. GaAs, InP
• CPC Class Codes: H01L 31/1844 comprising ternary or quaternary compounds, e.g. Ga Al As, In Ga As P
• CPC Class Codes: H01L 31/1848 comprising nitride compounds, e.g. InGaN, InGaAlN
• CPC Class Codes: H01L 33/08 : with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/20 : with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/38 : with a particular shape
• CPC Class Codes: H01L 33/382 : the electrode extending partially in or entirely through the semiconductor body
• CPC Class Codes: H01L 33/56 : Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H10K 50/80 : Constructional details
• CPC Class Codes: H10K 50/805 : Electrodes
• CPC Class Codes: H10K 59/17 : Passive-matrix OLED displays
• CPC Class Codes: H10K 59/805 : Electrodes
• CPC Class Codes: H10K 59/90 : Assemblies of multiple devices comprising at least one organic light-emitting element
• CPC Class Codes: H10K 71/00 : Manufacture or treatment specially adapted for the organic devices covered by this subclass
• CPC Class Codes: Y02E 10/50 : Photovoltaic [PV] energy
• CPC Class Codes: Y02E 10/544 : Solar cells from Group III-V materials
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product

Abstract

An exemplary printable composition of a liquid or gel suspension of diodes comprises a plurality of diodes, a first solvent and/or a viscosity modifier. An exemplary method of making a liquid or gel suspension of diodes comprises: adding a viscosity modifier to a plurality of diodes in a first solvent; and mixing the plurality of diodes, the first solvent and the viscosity modifier to form the liquid or gel suspension of the plurality of diodes. Various exemplary diodes have a lateral dimension between about 10 to 50 microns and about 5 to 25 microns in height. Other embodiments may also include a plurality of substantially chemically inert particles having a range of sizes between about 10 to about 50 microns.

Claims

1. A method of making a liquid or gel suspension of diodes for printing, the method comprising:

adding a viscosity modifier to a plurality of diodes in a first solvent;

mixing the plurality of diodes, the first solvent and the viscosity modifier to form the liquid or gel suspension of the plurality of diodes.

2. The method of claim 1, wherein the liquid or gel suspension of the plurality of diodes is mixed until the viscosity is at least about 100 centipoise (cps) measured at about 25°

C.

3. The method of claim 1, wherein the liquid or gel suspension of the plurality of diodes is mixed until the viscosity is at least about 1,000 centipoise (cps) measured at about 25°

C.

4. The method of claim 1, further comprising:

adding a plurality of substantially chemically inert particles to the mixture of the plurality of diodes, the first solvent and the viscosity modifier.

5. The method of claim 4, wherein each particle of the plurality of substantially chemically inert particles has a size between about 10 microns to about 70 microns in any dimension.

6. The method of claim 4, wherein the plurality of substantially chemically inert particles are substantially optically transmissive and each particle of the plurality of substantially chemically inert particles has a size between about 10 microns to about 30 microns in any dimension.

7. The method of claim 6, wherein the plurality of substantially chemically inert particles are comprised of a silica glass.

8. The method of claim 1, wherein the first solvent comprises at least one solvent selected from the group consisting of:

water;

alcohols such as methanol, ethanol, N-propanol (including 1-propanol, 2-propanol (isopropanol), 1-methoxy-2-propanol), butanol (including 1-butanol, 2-butanol (isobutanol), pentanol (including 1-pentanol, 2-pentanol, 3-pentanol), octanol, N-octanol (including 1-octanol, 2-octanol, 3-octanol), tetrahydrofurfuryl alcohol, cyclohexanol, terpineol;

ethers such as methyl ethyl ether, diethyl ether, ethyl propyl ether, and polyethers;

esters such ethyl acetate, dimethyl adipate, propylene glycol monomethyl ether acetate, dimethyl glutarate, dimethyl succinate, glycerin acetate;

glycols such as ethylene glycols, diethylene glycol, polyethylene glycols, propylene glycols, dipropylene glycols, glycol ethers, glycol ether acetates;

carbonates such as propylene carbonate;

glycerols such as glycerin;

acetonitrile, tetrahydrofuran (THF), dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide (DMSO); and

mixtures thereof.

9. The method of claim 1, wherein the viscosity modifier comprises at least one viscosity modifier selected from the group consisting of:

clays such as hectorite clays, garamite clays, organo-modified clays;

saccharides and polysaccharides such as guar gum, xanthan gum;

celluloses and modified celluloses such as hydroxy methylcellulose, methylcellulose, ethyl cellulose, propyl methylcellulose, methoxy cellulose, methoxy methylcellulose, methoxy propyl methylcellulose, hydroxy propyl methylcellulose, carboxy methylcellulose, hydroxy ethylcellulose, ethyl hydroxyl ethylcellulose, cellulose ether, cellulose ethyl ether, chitosan;

polymers such as acrylate and (meth)acrylate polymers and copolymers;

glycols such as ethylene glycols, diethylene glycol, polyethylene glycols, propylene glycols, dipropylene glycols, glycol ethers, glycol ether acetates;

fumed silica, silica powders;

modified ureas; and

mixtures thereof.

10. The method of claim 1, further comprising:

adding a second solvent to the plurality of diodes, the first solvent and the viscosity modifier, the second solvent different from the first solvent; and

mixing the plurality of diodes, the first solvent, the second solvent, and the viscosity modifier.

11. The method of claim 10, wherein the second solvent is at least one solvent selected from the group consisting of:

water;

alcohols such as methanol, ethanol, N-propanol (including 1-propanol, 2-propanol (isopropanol), 1-methoxy-2-propanol), butanol (including 1-butanol, 2-butanol (isobutanol), pentanol (including 1-pentanol, 2-pentanol, 3-pentanol), octanol, N-octanol (including 1-octanol, 2-octanol, 3-octanol), tetrahydrofurfuryl alcohol, cyclohexanol, terpineol;

ethers such as methyl ethyl ether, diethyl ether, ethyl propyl ether, and polyethers;

esters such ethyl acetate, dimethyl adipate, propylene glycol monomethyl ether acetate, dimethyl glutarate, dimethyl succinate, glycerin acetate;

glycols such as ethylene glycols, diethylene glycol, polyethylene glycols, propylene glycols, dipropylene glycols, glycol ethers, glycol ether acetates;

carbonates such as propylene carbonate;

glycerols such as glycerin;

acetonitrile, tetrahydrofuran (THF), dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide (DMSO); and

mixtures thereof.

12. The method of claim 10, further comprising:

mixing the plurality of diodes, the first solvent, the second solvent, and the viscosity modifier for about 25 to 30 minutes in an air atmosphere.

13. The method of claim 10, wherein the first solvent comprises N-propanol, isopropanol, dipropylene glycol, diethylene glycol, propylene glycol, 1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, or cyclohexanol, or mixtures thereof, and present in an amount of about 5% to 50% by weight;

wherein the viscosity modifier comprises methoxy propyl methylcellulose resin or hydroxy propyl methylcellulose resin or mixtures thereof, and present in an amount of about 0.10% to 5.0% by weight;

wherein the second solvent comprises N-propanol, isopropanol, dipropylene glycol, diethylene glycol, propylene glycol, 1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, or cyclohexanol, or mixtures thereof, and present in an amount of about 0.3% to 50% by weight.

14. The method of claim 13, further comprising:

adding a plurality of substantially optically transparent and chemically inert particles having a range of sizes between about 10 to about 50 microns and present in an amount of about 0.1% to 2.5% by weight.

15. The method of claim 10, wherein the first solvent comprises N-propanol, isopropanol, dipropylene glycol, diethylene glycol, propylene glycol, 1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, or cyclohexanol, or mixtures thereof, and present in an amount of about 5% to 30% by weight;

wherein the viscosity modifier comprises methoxy propyl methylcellulose resin or hydroxy propyl methylcellulose resin or mixtures thereof, and present in an amount of about 1.0% to 3.0% by weight;

wherein the second solvent comprises N-propanol, isopropanol, dipropylene glycol, diethylene glycol, propylene glycol, 1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, or cyclohexanol, or mixtures thereof, and present in an amount of about 0.2% to 8.0% by weight; and

wherein the balance of the method further comprises water.

16. The method of claim 15, further comprising:

adding a plurality of substantially optically transparent and chemically inert particles having a range of sizes between about 10 to about 50 microns and present in an amount of about 0.1% to 2.5% by weight.

17. The method of claim 10, wherein the first solvent comprises N-propanol, isopropanol, dipropylene glycol, diethylene glycol, propylene glycol, 1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, or cyclohexanol, or mixtures thereof, and present in an amount of about 40% to 60% by weight;

wherein the viscosity modifier comprises methoxy propyl methylcellulose resin or hydroxy propyl methylcellulose resin or mixtures thereof, and present in an amount of about 0.10% to 1.5% by weight;

wherein the second solvent comprises N-propanol, isopropanol, dipropylene glycol, diethylene glycol, propylene glycol, 1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, or cyclohexanol, or mixtures thereof, and present in an amount of about 40% to 60% by weight.

18. The method of claim 17, further comprising:

adding a plurality of substantially optically transparent and chemically inert particles having a range of sizes between about 10 to about 50 microns and present in an amount of about 0.1% to 2.5% by weight.

19. The method of claim 10, wherein the second solvent is at least one dibasic ester.

20. The method of claim 10, wherein the second solvent comprises:

dimethyl glutarate; and

dimethyl succinate;

wherein the ratio of dimethyl glutarate to dimethyl succinate is about two to one (2;

1).

21. The method of claim 10, wherein the second solvent is present in an amount of about 0.1% to 10% by weight.

22. The method of claim 10, wherein the second solvent is present in an amount of about 10% to 50% by weight.

23. The method of claim 1, wherein prior to the step of adding a viscosity modifier, the method further comprising:

releasing the plurality of diodes from a wafer into a third solvent.

24. The method of claim 23, wherein the step of releasing the plurality of diodes from the wafer further comprises etching a second, back side of the wafer.

25. The method of claim 23, wherein the step of releasing the plurality of diodes from the wafer further comprises grinding and polishing a second, back side of the wafer.

26. The method of claim 23, wherein the step of releasing the plurality of diodes from the wafer further comprises using a laser to perform a laser lift-off of the plurality of diodes from a second, back of the wafer.

27. The method of claim 23, further comprising:

substantially removing the third solvent; and

adding the first solvent.

28. The method of claim 27, further comprising:

repeating the steps of substantially removing the third solvent and adding the first solvent until the amount of the third solvent remaining is under 1.0% by weight.

29. The method of claim 1, wherein each diode of the plurality of diodes comprises GaN and wherein the GaN portion of each diode of the plurality of diodes is substantially hexagonal, square, triangular, rectangular, lobed, stellate, or toroidal.

30. The method of claim 1, wherein the light emitting or absorbing region of each diode of the plurality of diodes has a surface texture comprising a plurality of circular rings, or a plurality of substantially curvilinear trapezoids, or a plurality of parallel stripes, or a stellate pattern.

31. The method of claim 1, wherein each diode of the plurality of diodes has a diameter between about 20 to 30 microns and a height between about 5 to 15 microns.

32. The method of claim 1, wherein each diode of the plurality of diodes has a diameter between about 10 to 50 microns and a height between about 5 to 25 microns.

33. The method of claim 1, wherein each diode of the plurality of diodes is substantially hexagonal laterally, has a diameter between about 10 to 50 microns measured opposing face-to face, and a height between about 5 to 25 microns.

34. The method of claim 1, wherein each diode of the plurality of diodes is substantially hexagonal laterally, has a diameter measured opposing face-to face between about 20 to 30 microns and a height between about 5 to 15 microns.

35. The method of claim 1, wherein each diode of the plurality of diodes has a width and length each between about 10 to 50 microns each and a height between about 5 to 25 microns.

36. The method of claim 1, wherein each diode of the plurality of diodes has a width and length each between about 20 to 30 microns each and a height between about 5 to 15 microns.

37. The method of claim 1, wherein each diode of the plurality of diodes has a first metal terminal on a first side of the diode and a second metal terminal on a second, back side of the diode.

39. The method of claim 31, wherein the first and second terminals are each between about 1 to 6 microns in height.

40. The method of claim 1, wherein each diode of the plurality of diodes has a plurality of first metal terminals on a first side and one second metal terminal on the first side, the second metal terminal having one contact, and the one contact of the second metal terminal spaced apart from contacts of the plurality of first metal terminals by about 1 to 7 microns in height.

41. The method of claim 40, wherein each first metal terminal of the plurality of first metal terminals is between 0.5 to 2 microns in height and the second metal terminal is between about 1 to 8 microns in height and the sides of the second metal terminal are passivated.

42. The method of claim 1, wherein lateral sides of each diode of the plurality of diodes are less than 10 microns in height.

43. The method of claim 1, wherein lateral sides of each diode of the plurality of diodes are between about 2.5 to 6 microns in height.

44. The method of claim 1, wherein lateral sides of each diode of the plurality of diodes is substantially sigmoidal and terminates in a curved point.

45. The method of claim 1, wherein the viscosity modifier, when dried or cured, forms a polymer or resin lattice or structure substantially about the periphery of each diode of the plurality of diodes.

46. The method of claim 1, wherein the liquid or gel suspension of the plurality of diodes is visually opaque when wet and substantially optically clear when dried or cured.

47. The method of claim 1, wherein the liquid or gel suspension of the plurality of diodes has a contact angle greater than about 25 degrees or greater than about 40 degrees.

48. The method of claim 1, wherein the plurality of diodes comprises at least one inorganic semiconductor selected from the group consisting of:

silicon, gallium arsenide (GaAs), gallium nitride (GaN), GaP, InAlGaP, InAlGaP, AlInGaAs, InGaNAs, and AlInGASb.

49. The method of claim 1, wherein the plurality of diodes comprises at least one organic semiconductor selected from the group consisting of:

π

-conjugated polymers, poly(acetylene)s, poly(pyrrole)s, poly(thiophene)s, polyanilines, polythiophenes, poly(p-phenylene sulfide), poly(para-phenylene vinylene)s (PPV) and PPV derivatives, poly(3-alkylthiophenes), polyindole, polypyrene, polycarbazole, polyazulene, polyazepine, poly(fluorene)s, polynaphthalene, polyaniline, polyaniline derivatives, polythiophene, polythiophene derivatives, polypyrrole, polypyrrole derivatives, polythianaphthene, polythianaphthane derivatives, polyparaphenylene, polyparaphenylene derivatives, polyacetylene, polyacetylene derivatives, polydiacethylene, polydiacetylene derivatives, polyparaphenylenevinylene, polyparaphenylenevinylene derivatives, polynaphthalene, polynaphthalene derivatives, polyisothianaphthene (PITN), polyheteroarylenvinylene (ParV) in which the heteroarylene group is thiophene, furan or pyrrol, polyphenylene-sulphide (PPS), polyperinaphthalene (PPN), polyphthalocyanine (PPhc), and their derivatives, copolymers thereof and mixtures thereof.

50. The method of claim 1, wherein the liquid or gel suspension of the plurality of diodes has a relative evaporation rate less than one, wherein the evaporation rate is relative to butyl acetate having a rate of one.

51. A method of using the liquid or gel suspension of the plurality of diodes of claim 1, the method comprising:

printing the liquid or gel suspension of the plurality of diodes over a base or over a first conductor coupled to the base.

52. The method of claim 1, wherein the first solvent comprises dipropylene glycol, or N-propanol, or 1-octanol, or 1-methoxy-2-propanol, or propylene glycol, or mixtures thereof.

53. The method of claim 1, wherein the first solvent is present in an amount of about 0.3% to 60% by weight.

54. The method of claim 1, wherein the viscosity modifier comprises a methylcellulose resin.

55. The method of claim 1, wherein the viscosity modifier comprises a hydroxy propyl methylcellulose resin or a methoxy propyl methylcellulose resin or a mixture thereof.

56. The method of claim 1, wherein the viscosity modifier is present in an amount of about 0.10% to 5% by weight.

57. The method of claim 1, wherein the liquid or gel suspension of the plurality of diodes has a viscosity greater than about 100 centipoise (cps) measured at about 25°

C.

58. The method of claim 1, wherein the liquid or gel suspension of the plurality of diodes has a viscosity between about 1,000 centipoise (cps) and about 25,000 centipoise (cps) measured at about 25°

C.

59. The method of claim 1, wherein the liquid or gel suspension of the plurality of diodes has a viscosity between about 1,000 centipoise (cps) and about 10,000 centipoise (cps) measured at about 25°

C.

60. The method of claim 1, wherein the liquid or gel suspension of the plurality of diodes has a viscosity between about 10,000 centipoise (cps) and about 25,000 centipoise (cps) measured at about 25°

C.

61. The method of claim 1, wherein the liquid or gel suspension of the plurality of diodes has a viscosity between about 20,000 centipoise (cps) and about 60,000 centipoise (cps) measured between about 5°

C. and 10°

C.

62. A method of making a liquid or gel suspension of diodes for printing, the method comprising:

adding a second solvent to a plurality of diodes in a first solvent, the second solvent different from the first solvent;

adding a viscosity modifier to the plurality of diodes, the first solvent and the second solvent;

adding a plurality of substantially chemically inert particles to the plurality of diodes, the first solvent, the second solvent and the viscosity modifier; and

mixing the plurality of diodes, the first solvent, the second solvent, the viscosity modifier, and the plurality of substantially chemically inert particles until the viscosity is at least about 100 centipoise (cps) measured at about 25°

C. to form the liquid or gel suspension of the plurality of diodes.

63. The method of claim 62, wherein each diode of the plurality of diodes has a lateral dimension between about 10 to 50 microns and a height between about 5 to 25 microns.

64. The method of claim 62, wherein each particle of the plurality of substantially chemically inert particles has a size between about 10 microns to about 70 microns in any dimension.

65. The method of claim 62, wherein the first solvent comprises at least one solvent selected from the group consisting of:

water;

alcohols such as methanol, ethanol, N-propanol (including 1-propanol, 2-propanol (isopropanol), 1-methoxy-2-propanol), butanol (including 1-butanol, 2-butanol (isobutanol), pentanol (including 1-pentanol, 2-pentanol, 3-pentanol), octanol, N-octanol (including 1-octanol, 2-octanol, 3-octanol), tetrahydrofurfuryl alcohol, cyclohexanol, terpineol;

ethers such as methyl ethyl ether, diethyl ether, ethyl propyl ether, and polyethers;

esters such ethyl acetate, dimethyl adipate, propylene glycol monomethyl ether acetate, dimethyl glutarate, dimethyl succinate, glycerin acetate;

glycols such as ethylene glycols, diethylene glycol, polyethylene glycols, propylene glycols, dipropylene glycols, glycol ethers, glycol ether acetates;

carbonates such as propylene carbonate;

glycerols such as glycerin;

acetonitrile, tetrahydrofuran (THF), dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide (DMSO); and

mixtures thereof.

66. The method of claim 62, wherein the viscosity modifier comprises at least one viscosity modifier selected from the group consisting of:

clays such as hectorite clays, garamite clays, organo-modified clays;

saccharides and polysaccharides such as guar gum, xanthan gum;

celluloses and modified celluloses such as hydroxy methylcellulose, methylcellulose, ethyl cellulose, propyl methylcellulose, methoxy cellulose, methoxy methylcellulose, methoxy propyl methylcellulose, hydroxy propyl methylcellulose, carboxy methylcellulose, hydroxy ethylcellulose, ethyl hydroxyl ethylcellulose, cellulose ether, cellulose ethyl ether, chitosan;

polymers such as acrylate and (meth)acrylate polymers and copolymers;

glycols such as ethylene glycols, diethylene glycol, polyethylene glycols, propylene glycols, dipropylene glycols, glycol ethers, glycol ether acetates;

fumed silica, silica powders;

modified ureas; and

mixtures thereof.

67. The method of claim 62, wherein the second solvent is at least one solvent selected from the group consisting of:

water;

alcohols such as methanol, ethanol, N-propanol (including 1-propanol, 2-propanol (isopropanol), 1-methoxy-2-propanol), butanol (including 1-butanol, 2-butanol (isobutanol), pentanol (including 1-pentanol, 2-pentanol, 3-pentanol), octanol, N-octanol (including 1-octanol, 2-octanol, 3-octanol), tetrahydrofurfuryl alcohol, cyclohexanol, terpineol;

ethers such as methyl ethyl ether, diethyl ether, ethyl propyl ether, and polyethers;

esters such ethyl acetate, dimethyl adipate, propylene glycol monomethyl ether acetate, dimethyl glutarate, dimethyl succinate, glycerin acetate;

glycols such as ethylene glycols, diethylene glycol, polyethylene glycols, propylene glycols, dipropylene glycols, glycol ethers, glycol ether acetates;

carbonates such as propylene carbonate;

glycerols such as glycerin;

acetonitrile, tetrahydrofuran (THF), dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide (DMSO); and

mixtures thereof.

68. The method of claim 62, wherein the first solvent comprises N-propanol, isopropanol, dipropylene glycol, diethylene glycol, propylene glycol, 1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, or cyclohexanol, or mixtures thereof, and present in an amount of about 5% to 60% by weight;

wherein the viscosity modifier comprises methoxy propyl methylcellulose resin or hydroxy propyl methylcellulose resin or mixtures thereof, and present in an amount of about 0.10% to 5.0% by weight;

wherein the second solvent comprises N-propanol, isopropanol, dipropylene glycol, diethylene glycol, propylene glycol, 1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, or cyclohexanol, or mixtures thereof, and present in an amount of about 0.3% to 60% by weight.

69. The method of claim 62, wherein lateral sides of each diode of the plurality of diodes are less than 10 microns in height.

70. The method of claim 62, wherein lateral sides of each diode of the plurality of diodes is substantially sigmoidal and terminates in a curved point.

71. A method of making a liquid or gel suspension of diodes for printing, the method comprising:

adding a viscosity modifier to a plurality of diodes, a first solvent and a second solvent, the second solvent different from the first solvent, wherein each diode of the plurality of diodes has a lateral dimension between about 10 to 50 microns and a height between about 5 to 25 microns;

adding a plurality of substantially chemically inert particles to the plurality of diodes, the first solvent, the second solvent and the viscosity modifier, wherein each particle of the plurality of substantially chemically inert particles has a size between about 10 microns to about 70 microns in any dimension; and

mixing the plurality of diodes, the first solvent, the second solvent, the viscosity modifier, and the plurality of substantially chemically inert particles until the viscosity is at least about 1,000 centipoise (cps) measured at about 25°

C. to form the liquid or gel suspension of the plurality of diodes.

72. The method of claim 71, wherein the first solvent comprises at least one solvent selected from the group consisting of:

water;

alcohols such as methanol, ethanol, N-propanol (including 1-propanol, 2-propanol (isopropanol), 1-methoxy-2-propanol), butanol (including 1-butanol, 2-butanol (isobutanol), pentanol (including 1-pentanol, 2-pentanol, 3-pentanol), octanol, N-octanol (including 1-octanol, 2-octanol, 3-octanol), tetrahydrofurfuryl alcohol, cyclohexanol, terpineol;

ethers such as methyl ethyl ether, diethyl ether, ethyl propyl ether, and polyethers;

esters such ethyl acetate, dimethyl adipate, propylene glycol monomethyl ether acetate, dimethyl glutarate, dimethyl succinate, glycerin acetate;

glycols such as ethylene glycols, diethylene glycol, polyethylene glycols, propylene glycols, dipropylene glycols, glycol ethers, glycol ether acetates;

carbonates such as propylene carbonate;

glycerols such as glycerin;

acetonitrile, tetrahydrofuran (THF), dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide (DMSO); and

mixtures thereof.

73. The method of claim 71, wherein the viscosity modifier comprises at least one viscosity modifier selected from the group consisting of:

clays such as hectorite clays, garamite clays, organo-modified clays;

saccharides and polysaccharides such as guar gum, xanthan gum;

celluloses and modified celluloses such as hydroxy methylcellulose, methylcellulose, ethyl cellulose, propyl methylcellulose, methoxy cellulose, methoxy methylcellulose, methoxy propyl methylcellulose, hydroxy propyl methylcellulose, carboxy methylcellulose, hydroxy ethylcellulose, ethyl hydroxyl ethylcellulose, cellulose ether, cellulose ethyl ether, chitosan;

polymers such as acrylate and (meth)acrylate polymers and copolymers;

glycols such as ethylene glycols, diethylene glycol, polyethylene glycols, propylene glycols, dipropylene glycols, glycol ethers, glycol ether acetates;

fumed silica, silica powders;

modified ureas; and

mixtures thereof.

74. The method of claim 71, wherein the second solvent is at least one solvent selected from the group consisting of:

water;

alcohols such as methanol, ethanol, N-propanol (including 1-propanol, 2-propanol (isopropanol), 1-methoxy-2-propanol), butanol (including 1-butanol, 2-butanol (isobutanol), pentanol (including 1-pentanol, 2-pentanol, 3-pentanol), octanol, N-octanol (including 1-octanol, 2-octanol, 3-octanol), tetrahydrofurfuryl alcohol, cyclohexanol, terpineol;

ethers such as methyl ethyl ether, diethyl ether, ethyl propyl ether, and polyethers;

esters such ethyl acetate, dimethyl adipate, propylene glycol monomethyl ether acetate, dimethyl glutarate, dimethyl succinate, glycerin acetate;

glycols such as ethylene glycols, diethylene glycol, polyethylene glycols, propylene glycols, dipropylene glycols, glycol ethers, glycol ether acetates;

carbonates such as propylene carbonate;

glycerols such as glycerin;

acetonitrile, tetrahydrofuran (THF), dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide (DMSO); and

mixtures thereof.

75. The method of claim 71, wherein the first solvent comprises N-propanol, isopropanol, dipropylene glycol, diethylene glycol, propylene glycol, 1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, or cyclohexanol, or mixtures thereof, and present in an amount of about 5% to 60% by weight;

wherein the viscosity modifier comprises methoxy propyl methylcellulose resin or hydroxy propyl methylcellulose resin or mixtures thereof, and present in an amount of about 0.10% to 0.5% by weight;

wherein the second solvent comprises N-propanol, isopropanol, dipropylene glycol, diethylene glycol, propylene glycol, 1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, or cyclohexanol, or mixtures thereof, and present in an amount of about 0.3% to 60% by weight.

76. The method of claim 71, wherein lateral sides of each diode of the plurality of diodes are less than 10 microns in height.

77. The method of claim 71, wherein lateral sides of each diode of the plurality of diodes is substantially sigmoidal and terminates in a curved point.