U.S. patent application number 13/928143 was filed with the patent office on 2014-01-02 for systems and methods for fabrication of nanostructures.
This patent application is currently assigned to NthDegree Technologies Worldwide Inc.. The applicant listed for this patent is NthDegree Technologies Worldwide Inc.. Invention is credited to John Gustafson, Vera N. Lockett, Mark D. Lowenthal, William J. Ray.
Application Number | 20140001421 13/928143 |
Document ID | / |
Family ID | 49777141 |
Filed Date | 2014-01-02 |
United States Patent
Application |
20140001421 |
Kind Code |
A1 |
Lockett; Vera N. ; et
al. |
January 2, 2014 |
SYSTEMS AND METHODS FOR FABRICATION OF NANOSTRUCTURES
Abstract
Systems and methods for fabricating nanostructures using other
nanostructures as templates. A method includes mixing a dispersion
and a reagent solution. The dispersion includes nanostructures such
as nanowires including a first element such as copper. The reagent
solution includes a second element such as silver. The second
element at least partially replaces the first element in the
nanostructures. The nanostructures are optionally washed, filtered,
and/or deoxidized.
Inventors: |
Lockett; Vera N.; (Phoenix,
AZ) ; Lowenthal; Mark D.; (Gilbert, AZ) ; Ray;
William J.; (Fountain Hills, AZ) ; Gustafson;
John; (Tempe, AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NthDegree Technologies Worldwide Inc. |
Tempe |
AZ |
US |
|
|
Assignee: |
NthDegree Technologies Worldwide
Inc.
Tempe
AZ
|
Family ID: |
49777141 |
Appl. No.: |
13/928143 |
Filed: |
June 26, 2013 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61665796 |
Jun 28, 2012 |
|
|
|
Current U.S.
Class: |
252/514 ;
75/370 |
Current CPC
Class: |
H01B 13/00 20130101;
B22F 9/24 20130101; H01B 1/026 20130101; H01B 1/02 20130101; C09D
11/52 20130101 |
Class at
Publication: |
252/514 ;
75/370 |
International
Class: |
H01B 1/02 20060101
H01B001/02; H01B 13/00 20060101 H01B013/00 |
Claims
1. A method comprising: mixing a dispersion and a reagent solution,
the dispersion including nanostructures comprising a first element,
the reagent solution including a second element, the second element
at least partially replacing the first element in the nano
structures.
2. The method of claim 1, wherein the nanostructures comprise
nanowires.
3. The method of claim 1, wherein the first element is copper.
4. The method of claim 1, wherein the second element is silver.
5. The method of claim 1, wherein a concentration of the
nanostructures in the dispersion is between about 0.1 g/L and about
1 g/L.
6. The method of claim 1, wherein the dispersion includes at least
one selected from a group consisting of dispersants and
surfactants.
7. The method of claim 1, wherein a concentration of the reagent
solution is between about 0.1 M and about 0.15 M.
8. The method of claim 1, wherein the reagent solution comprises at
least one selected from a group consisting of silver nitrate and
silver ions.
9. A dispersion comprising: a solvent; and nanowires comprising
silver and having a length greater than about 10 microns in a
dimension, the nanowires dispersed in the solvent.
10. The dispersion of claim 9, wherein the length is greater than
about 25 microns in the dimension.
11. The dispersion of claim 9, wherein the nanowires comprise at
least about 10% silver.
12. The dispersion of claim 9, wherein the nanowires in films have
a resistivity less than about 7.5.times.10.sup.3 .OMEGA.m in a 2.0
vol % nanowires/low density polyethylene.
13. The dispersion of claim 9, wherein the nanowires in dispersion
have a visible light transmittance greater than about 70% at a
resistance of 15 .OMEGA./sq.
14. A method comprising: filtering a dispersion including nano
structures.
15. The method of claim 14, wherein the nanostructures comprise
nanowires.
16. The method of claim 14, wherein the nanostructures comprise
copper.
17. The method of claim 14, wherein filtering the nanostructures
includes using a non-fibrous filter.
18. The method of claim 14, further comprising dispersing the
nanostructures in a solvent.
19. The method of claim 14, further comprising deoxidizing the nano
structures.
20. The method of claim 19, wherein deoxidizing comprises mixing an
acid and a first dispersion including oxidized nanostructures.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/665,796, filed Jun. 28, 2012, entitled "Systems
and Methods for Fabrication of Nanostructures," the entirety of
which is hereby incorporated herein by reference. U.S. patent
application Ser. No. 13/360,999, filed Jan. 30, 2012, published as
U.S. Pub. No. 2012/0217453, entitled "Metallic Nanofiber Ink,
Substantially Transparent Conductor, and Fabrication Method," (the
'999 application) is hereby incorporated by reference in its
entirety.
BACKGROUND
[0002] 1. Field
[0003] The present application relates to fabrication of
nanostructures such as silver nanowires.
[0004] 2. Description of the Related Art
[0005] Materials reduced to the nanoscale exhibit different
physical and chemical properties compared to those on macroscale.
The different properties are due in part to the increase in surface
area to volume ratio, which alter mechanical, electrical, optical,
and catalytic properties of materials. Such distinctive properties
present in nanosized materials can depend on both the size and
shape of the materials.
[0006] Nanowires have attracted considerable attention due to the
interesting fundamental properties which can be utilized in
nanotechnology-enabled electronic, display, solar, filtration,
anti-microbial, adhesive, and other commercial applications. Among
many other potential applications, layers formed from dispersions
of nanowirescan potentially replace a widely used transparent
conductor, indium tin oxide (ITO). While ITO has a high light
transmittance and electrical conductivity (e.g., depending on
thickness, composition, etc., 90% over the visible spectrum between
400 nm and 700 nm and resistivity of 120 .OMEGA./sq), ITO is
brittle, slow and difficult to deposit, expensive, and its
deposition entails handling of toxic precursor materials.
SUMMARY
[0007] Copper (Cu) nanowires (CuNW) are commercially available, but
their electrical conductivity (Cu resistivity
.rho.=1.7.times.10.sup.-6 .OMEGA.cm, or 9.25.times.10.sup.3
.OMEGA.m in a 2.0 vol % CuNW/low density polyethylene (LDPE)) and
light transmittance (65% at a resistance of 15 .OMEGA./sq)
properties in dispersions, meshes, inks, and/or films are not as
good as for silver (Ag) nanowires (AgNW) (Ag resistivity
.rho.=1.6.times.10.sup.-6 .OMEGA.cm, or less than
6.88.times.10.sup.2 .OMEGA.m in a 2.0 vol % AgNW/LDPE, and 85% at a
resistance of 15 .OMEGA./sq, respectively). Some AgNW meshes can
have a transmittance of about 92-93% at 15 .OMEGA./sq in a binder,
resin, or polymer. While AgNW are also commercially available, and
have a higher conductivity and light transmittance in films,
fabrication methods for AgNW are inefficient and expensive. Coating
the surface of CuNW with Ag is possible, but many of the same
problems of CuNW as described herein can persist with Ag-coated
CuNW.
[0008] Systems and methods disclosed herein can fabricate AgNW
using CuNW as templates. One advantage of certain embodiments
disclosed herein is that using CuNW as templates can aid in the
fabrication of relatively long AgNW as compared to previous AgNW
fabrication methods. For example, AgNW are generally less than
about 10 .mu.m long, and are typically about 4 microns (.mu.m) to
about 5 .mu.m long. By contrast, CuNW may be much longer, and use
of long CuNW as a template for AgNW can form long AgNW, for example
having a length greater than about 10 .mu.m, between about 70 .mu.m
and about 150 .mu.m, and other lengths. Longer AgNW can allow for
higher conductivity (lower resistivity) due to more cross points in
the percolative network. This higher conductivity may be achieved
while having less mass per square area, which can result in better
light transmittance. In CuNW and AgNW films, inks, and other
applications, conductivity and transmittance have an inverse
relationship--conductivity decreases as transmittance increases.
Certain fabrication processes disclosed herein can advantageously
control the size of the AgNW by using CuNW as templates, reducing
Ag waste, and thereby reducing costs. The reduced costs can allow
for use of AgNW in a wide variety of applications such as, for
example, solar panels, touch screens, and displays. Replacing ITO
with metal nanowires can provide many of the benefits of ITO while
allowing for use in more versatile applications such as, for
example, conductive inks, polymers, and flexible films for displays
and/or solar panels, and the like. Some uses of conductive inks and
polymers are described in more detail in the '999 application. Some
embodiments of metal nanowires can maintain their light
transmittance and electrical conductivity properties even under
mechanical deformation. In certain such applications, such as
conductive ink applications, AgNW benefits can include, but are not
limited to, (1) low resistance per given optical transparency, (2)
high transmittance of light over a broad range of wavelengths
(useful in solar panels), and (3) mechanical flexibility
(application to curved surfaces or flexible devices,
durability).
[0009] In addition, AgNW have a higher resistance to corrosion as
compared to CuNW. Conductivity degrades with oxidation. In
fabrication steps or applications with exposure to a corroding
environment, CuNW can oxidize quickly and conductivity degrades.
For example, printed electronics using electrically conductive
fillers in polymer composites or active inks used in magazines,
consumer packaging, and clothing designs are often exposed to
oxidizing environments. Reducing AgNW costs may allow for AgNW to
be cost-effectively used in such applications, generally without
degradation of conductivity.
[0010] Systems and methods for fabricating a nanostructure using
another nanostructure as a template are disclosed herein. A method
includes mixing a dispersion and a reagent solution. The dispersion
includes nanostructures including a first element, such as copper.
The reagent solution includes a second element, such as silver. The
second element at least partially replaces the first element in the
nanostructures. The nanostructures are optionally washed, filtered,
and/or deoxidized. In certain embodiments, the fabrication includes
providing CuNW that are washed, filtered, and/or deoxidized, and
dispersed in a dispersion. Silver in a solution may be added to the
CuNW dispersion, or vice versa. In a chemical replacement reaction,
the Ag in the mixture and the Ag takes the place of the Cu in the
nanowire to form a AgNW. Thus, the CuNW may act as a template for
the AgNW.
[0011] In some embodiments, a method comprises mixing a dispersion
and a reagent solution. The dispersion includes nanostructures
comprising a first element. The reagent solution includes a second
element. The second element at least partially replaces the first
element in the nanostructures.
[0012] The nanostructures may include nanowires. The first element
may be copper. The second element may be silver. The concentration
of the nanostructures in the dispersion before mixing may be
between about 0.1 g/L and about 1 g/L. The dispersion may include
dispersants and surfactants. The dispersion may include organic
solvents. The dispersion may include polyvinylpyrrolidone, bile
salts, water, ethanol, combinations thereof, and/or the like.
[0013] The reagent solution concentration before mixing may be
between about 0.1 mol/L (molar, M) and about 0.15 M. The reagent
solution may include silver nitrate silver ions, combinations
thereof, and/or the like. The reagent solution may be slowly added
to the dispersion, such as adding the reagent solution drop-wise to
the dispersion. The mixing of the reagent solution with the
dispersion may include vigorously stirring with a stirrer, such as
a magnetic stirrer.
[0014] The second element may partially or fully replace the first
element in the nanostructure. The second element may replace at
least about 5%, about 25%, about 50%, about 75%, about 90%, about
95%, about 100% of the first element, and/or combinations thereof.
After mixing, the nanostructures in dispersion may have a
resistivity less than about 7.5.times.10.sup.3 .OMEGA.m in a 2.0
vol % nanostructures/low density polyethylene and/or may have a
light transmittance greater than about 70% at a resistance of 15
.OMEGA./sq.
[0015] The nanostructures may be filtered out before mixing. The
filtering may include using a non-porous filter. The filter may
have pore sizes of about 0.2 microns or less. The filter may
comprise Teflon. The nanostructures may be dispersed during any of
the steps of the fabrication process. Dispersing the nanostructures
may include dispersing in a solvent. The solvent may comprise
water. The solvent may comprise an organic solvent. The organic
solvent may comprise ethanol. The solvent may include at least one
of dispersants and surfactants. The solvent may include
polyvinylpyrrolidone, bile salts, combinations thereof, and/or the
like. The nanostructures may be deoxidized. Deoxidizing may include
mixing an acid and a first dispersion including oxidized
nanostructures. The acid may comprise 0.05 M HCl. The filter may be
stable in acids in low concentrations. The deoxidized
nanostructures may be dispersed in a solvent. The solvent may
comprise water. The solvent may comprise an organic solvent. The
organic solvent may comprise ethanol. The solvent may include at
least one of dispersants and surfactants. The solvent may include
polyvinylpyrrolidone, bile salts, combinations thereof, and/or the
like. The nanostructures, after mixing, may be added to an ink. The
ink may be printed to form a transparent conductive portion of a
device. The device may be a solar device, display device, and/or
the like.
[0016] In some embodiments, a method comprises filtering a
dispersion including nanostructures.
[0017] The nanostructures may include nanowires. The nanostructures
comprise copper. The concentration of the nanostructures in the
dispersion may be between about 0.1 g/L and about 1 g/L. The
dispersion may include dispersants and surfactants. The dispersion
may include organic solvents. The dispersion may include
polyvinylpyrrolidone, bile salts, water, ethanol, combinations
thereof, and/or the like. The filtering may include using a
non-porous filter. The filter may have pore sizes of about 0.2
microns or less. The filter may comprise Teflon. The nanostructures
may be dispersed in a solvent. The solvent may comprise water. The
solvent may comprise an organic solvent. The organic solvent may
comprise ethanol. The solvent may include at least one of
dispersants and surfactants. The solvent may include
polyvinylpyrrolidone, bile salts, combinations thereof, and/or the
like. The nanostructures may be deoxidized. Deoxidizing may include
mixing an acid and a first dispersion including oxidized
nanostructures. The acid may comprise 0.05 M HCl. The mixed acid
and first dispersion may be filtered through a filter. The filter
may be non-fibrous. The filter may have pore sizes of about 0.2
microns or less. The filter may comprise Teflon. The filter may be
stable in acids in low concentrations. The deoxidized
nanostructures may be dispersed in a solvent. The solvent may
comprise water. The solvent may comprise an organic solvent. The
organic solvent may comprise ethanol. The solvent may include at
least one of dispersants and surfactants. The solvent may include
polyvinylpyrrolidone, bile salts, combinations thereof, and/or the
like.
[0018] In some embodiments, a dispersion comprises a solvent and
nanowires comprising silver. The nanowires have a length greater
than about 10 microns in a dimension. The nanowires are dispersed
in the solvent.
[0019] The nanowires can have a length greater than about 25
microns, greater than about 50 microns, greater than about 70
microns, or greater than about 150 microns in a dimension. The
nanowires can have a length between about 10 microns and about 150
microns, between about 25 microns and about 150 microns, between
about 50 microns and about 150 microns, or between about 70 microns
and about 150 microns in the dimension. The nanowires may comprise
at least about 5%, at least about 10%, at least about 25%, at least
about 50%, at least about 75%, at least about 90%, or at least
about 95% silver. The nanowires may comprise less than about 5%,
less than about 10%, less than about 25%, less than about 50%, less
than about 75%, less than about 90%, or less than about 95% copper.
The nanowires may comprise about 100% silver. The nanowires may
comprise substantially no copper. The nanowires in films may have a
resistivity less than about 7.5.times.10.sup.3 .OMEGA.m in a 2.0
vol % nanowires/low density polyethylene. The nanowires in
dispersion may have a visible light transmittance greater than
about 70% at a resistance of 15 .OMEGA./sq. A concentration of the
nanowires may be between about 0.1 g/L and about 1 g/L. The solvent
may comprise water. The solvent may comprise organic solvent. The
organic solvent may comprise ethanol. The solvent may comprise at
least one of dispersants and surfactants. The solvent may comprise
polyvinylpyrrolidone. The solvent may comprise include bile salts.
A conductive ink may comprise the dispersion. A device may comprise
the conductive ink. The device may be a solar device, display
device, and/or the like.
[0020] The foregoing is a summary and thus contains, by necessity,
simplifications, generalization, and omissions of detail;
consequently, those skilled in the art will appreciate that the
summary is illustrative only and is not intended to be in any way
limiting. Other aspects, features, and advantages of the devices
and/or processes and/or other subject matter described herein will
become apparent in the teachings set forth herein. The summary is
provided to introduce a selection of concepts in a simplified form
that are further described below in the Detailed Description. This
summary is not intended to identify key features or essential
features of any subject matter described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The foregoing and other features of the present disclosure
will become more fully apparent from the following description,
taken in conjunction with the accompanying drawings. Understanding
that these drawings depict only some embodiments in accordance with
the disclosure and are, therefore, not to be considered limiting of
its scope, the disclosure will be described with additional
specificity and detail through use of the accompanying
drawings.
[0022] FIG. 1 illustrates an example embodiment of copper nanowires
dispersed in a dispersion;
[0023] FIG. 2 illustrates an example embodiment of a process for
washing, filtering, and deoxidizing copper nanowires dispersed in a
dispersion;
[0024] FIG. 3 illustrates an example embodiment of a process for
mixing a dispersion including nanostructures comprising and a first
element and a reagent solution including a second element in which
the second element at least partially replaces the first element in
the nanostructures; and
[0025] FIG. 4 depicts a simplified example of a process flow
diagram illustrating steps including dispersing, filtering,
deoxidizing, and/or mixing.
[0026] FIG. 5 depicts an example plot of resistance versus
transmissivity for an example embodiment of a silver nanowire
mesh.
DETAILED DESCRIPTION
[0027] In the following detailed description, reference is made to
the accompanying drawings, which form a part hereof. In the
drawings, similar symbols typically identify similar components,
unless context dictates otherwise. The illustrative embodiments
described in the detailed description and drawings are not meant to
be limiting. Other embodiments may be utilized, and other changes
may be made, without departing from the spirit or scope of the
subject matter presented here. It will be readily understood that
the aspects of the present disclosure, as generally described
herein, and illustrated in the Figures, may be arranged,
substituted, combined, and designed in a wide variety of different
configurations, all of which are explicitly contemplated and make
part of this disclosure.
[0028] In particular, the disclosed embodiments relate to
nanowires. This, however, is not intended to be limiting. It is to
be understood that, whenever "nanowire(s)" is mentioned herein,
this is to be read and understood as the more general terminology
"elongate nanostructure" or other crystalline nanostructures. The
term "elongate" generally means that the length is greater than the
width (diameter if cylindrical), but it will be appreciated that
within a plurality of nanostructures, some nanostructures may not
be considered "elongate." A "nanostructure," including nanowires,
can have a length on the order of microns and a width (diameter if
cylindrical) on the order of nanometers, but may be characterized
as a nanostructure or nanodevice on the basis of the order of
magnitude of the smaller dimension even if, based on the order of
magnitude of the larger dimension, it might alternatively be
characterized as a microstructure or microdevice. The nanowires may
be replaced by any other suitable elongate nanostructure, in
particular any two-dimensionally confined pieces of solid material
in the form of wires (nanowires), tubes (nanotubes), rods
(nanorods), and similar elongated substantially cylindrical or
polygonal nanostructures having a longitudinal axis, as well as
other crystalline nanostructures of varying shapes, sizes, volume,
and weight such as cubes, pyramids, bypyramids, spheres, and/or the
like, or any regular or any irregular shaped two-dimensional or
three-dimensional structure, including nanoclusters and
nanoplates.
[0029] The nanowires in some embodiments can be characterized as a
conductive nanowire having a diameter between about 1 nm and about
500 nm and length between about 5 nm and about 300 .mu.m. In
certain embodiments, the diameter of the nanowire is between about
20 nm and about 150 nm, and the length of the nanowire is between
about 10 .mu.m and about 150 .mu.m. In certain embodiments,
nanowires have an average length:width ratio greater than about
3:1, greater than about 6:1, greater than about 10:1, greater than
about 20:1, greater than about 50:1, greater than about 140:1,
greater than about 300:1, greater than about 1,000:1, greater than
about 2,000:1, greater than about 5,000:1, greater than about
10,000:1, greater than about 14,000:1, greater than about 20:000:1,
greater than about 30,000:1, greater than about 45,000:1, greater
than about 70,000:1, greater than about 100,000:1, greater than
about 125,000:1, or greater than about 150,000:1. Other average
length:width ratios are also possible.
Dispersion Including Nanostructures
[0030] FIG. 1 illustrates an example embodiment of copper nanowires
CuNW 2 dispersed in a dispersion 4. The size of the CuNW 2 are
exaggerated for the purposes of illustration. The CuNW 2 are
commercially available from such manufacturers as Nanoforge Corp.
of 2601 Weck Dr., Durham, N.C. 27709. The dispersion 4 can include
solvents and optionally includes dispersants and/or surfactants 6.
The solvents can include, for example, water, ethanol, isopropanol,
terpineol, ethylene glycol, dithylene glycol, combinations thereof,
and/or the like. Non-polar solvents may also be possible. In some
embodiments, dispersants and/or surfactants 6 comprise
polyvinylpyrrolidone (PVP) and/or bile salts. Dispersants can
include polymers such as, for example, polyethylene oxide,
polyoxyethylene nonylphenyl ether, polypropylene oxide,
polyoxyethylene glycol alkyl ethers, polyoxypropylene glycol alkyl
ethers, polyethoxylated tallow amine, poloxamers, polysorbate,
polymethylmetacrylic ammonium salt, polyacrylic ammonium salt,
polyacrylic amine salt, polyacrylic sodium salt, gum Arabic,
combinations thereof, and/or the like. Surfactants can include, for
example, sodium lauryl ether sulfate, sodium myreth sulfate,
ammonium lauryl sulfate, sodium dodecyl sulfate, alkyl aryl ether
phosphate, alkyl ether phosphate, perfluorooctanesulfonate,
perfluorobutanesulfonate, dioctyl sodium sulfosuccinate, alkyl
benzene sulfonates, sodium stearate, sodium lauryl sarcosinate,
perfluorononanoate, perfluorooctanoate, dimethyldioctadecylammonium
chloride, dioctadecyldimethylammonium bromide, octenidine
dihydrochloride, cetyl trimethylammonium bromide, cetyl
trimethylammonium chloride, cetylpyridinium chloride, benzalkonium
chloride, benzethonium chloride, 5-bromo-5-nitro-1,3-dioxane
(bronidox),
3-[(3-Cholamidopropyl)dimethylammonio]-1-propanesulfonate,
zwitterionic detergents, cocamidopropyl hydroxysultaine,
cocamidopropyl betaine, imino acids, amino acids, lecithin, cetyl
alcohol, stearyl alcohol, cetostearyl alcohol, oleyl alcohol,
octaethylene glycol monododecyl ether, pentaethylene glycol
monododecyl ether, decyl glucoside, lauryl glucoside, octyl
glucoside, Triton X-100, Nonoxynol-9, Daxad 19, glyceryl laurate,
dodecyldimethylamine oxide, cocamide MEA, cocamide DEA, spans,
combinations thereof, and/or the like. Dispersants can help inhibit
or prevent agglomeration of the CuNW 2. Surfactants can act as
dispersants, dispersants can act as surfactants, and certain
solvents, for example in combination with other solvents, may act
as dispersants and/or surfactants. Accordingly, any of the
compositions discussed herein may be considered a solvent, a
dispersant, or a surfactant depending on context. In some
embodiments, the dispersion 4 including CuNW 2 and dispersants
and/or surfactants 6 can be 10 microliters (.mu.L) of a 10% aqueous
dispersion of bile salts added to 50 mL of 0.2 g/L CuNW dispersion
4. The dispersion 4 including CuNW 2 and dispersants and/or
surfactants 6 can be contained in a beaker 8 or any other suitable
container.
[0031] The surface of the CuNW 2 can be oxidized and can have
adsorbed dispersants and/or surfactants 6. At least some of the
CuNW 2 in the dispersion 4 can be surface-oxidized CuNW 10. An
example transverse cross-section of a surface-oxidized CuNW 10 is
schematically illustrated in exploded view 12. An oxidized CuNW 10
can include a copper core 14 surrounded by a metal oxide coating 16
including cuprous oxide (Cu.sub.2O) and/or cupric oxide (CuO),
and/or dispersants and/or surfactants 6. Oxides can block reactive
sites on Cu to be replaced by Ag, as will be disclosed further
herein. In certain embodiments, the metal oxide coating 16 and
dispersants and/or surfactants 6 are removed, for example as
described herein. CuO can be reduced to Cu.sub.2O by ethylene
glycol and/or the like. Cu.sub.2O is thermodynamically unstable
outside the pH range 6-14 in aqueous environments, so Cu.sub.2O can
be decomposed using a solution with a pH below 6.
Filtering, Washing, and/or Deoxidizing
[0032] FIG. 2 illustrates an example embodiment of a process 18 for
washing, filtering, and deoxidizing copper nanowires 2 dispersed in
a dispersion 4. Some of the CuNW 2 may be only partially oxidized
and the dispersion 4 may include CuNW that are not oxidized. An
example cross-section of a surface-oxidized CuNW that may be
present in the dispersion 4 is illustrated in exploded view 10. The
process 18 can include removing dispersants and/or surfactants 6,
other impurities, metal oxide coatings 16, and/or CuNW smaller than
a certain size. In some embodiments, the CuNW 2 in the dispersion 4
can be further dispersed by adding solvents (including water,
alcohol such as, for example, ethanol, combinations thereof, and/or
the like), dispersants, and/or surfactants before being filtered or
passed through a filter 20. In certain embodiments, 50 mL of a 0.2
g/L CuNW dispersion 4 is filtered or passed through a filter 20 to
remove from the dispersion 4 dispersants and/or surfactants 6
(e.g., PVP), other impurities, and/or metal oxide coatings 16. In
certain embodiments, the filter 20 does not have fibers or is
non-fibrous because the CuNW 2 can become irrevocably caught on
filter fibers. The filter 20 can have pore sizes less than about
0.2 .mu.m, or less than about 100 .mu.m, less than about 70 .mu.m,
less than about 50 .mu.m, less than about 25 .mu.m, less than about
10 .mu.m, less than about 1 .mu.m, less than about 0.75 .mu.m, less
than about 0.5 .mu.m, less than about 0.45 .mu.m, less than about
0.4 .mu.m, less than about 0.35 .mu.m, less than about 0.3 .mu.m,
less than about 0.25 .mu.m, less than about 0.2 .mu.m, less than
about 0.15 .mu.m, less than about 0.1 .mu.m, less than about 0.05
.mu.m, less than about 0.025 .mu.m, and less than about 0.01 .mu.m,
including ranges bordered and including the foregoing values. In
some embodiments, the pore size of the filter 20 is selected based
on at least one of the desired size of the CuNW 2 to be filtered
out of the dispersion 4, the size of the material to be separated
from the filtrand 5 (e.g., impurities, dispersants such as PVP,
CuNW less than a certain size, combinations thereof, and/or the
like). The filter can be about 47 mm wide, or other sizes depending
on volume, pressure, temperature, filtration rate, etc. The filter
20 can be nitrocellulose mixed esters, nylon, polycarbonate,
polypropylene, polyethersulfone, polyvinylidene difluoride, Teflon
(polyfluoroethylene), combinations thereof, and/or the like.
[0033] After the CuNW dispersion 4 passes through the filter 20,
the filtrate 19 can include nanowires, solvents, dispersants (e.g.
PVP), impurities, surfactants, and/or other materials smaller than
the pore size of the filter 20 dispersed in dispersion 4. CuNW 2
and other material larger than the pore size of the filter 20 do
not pass through the filter 20. The CuNW 2 can be filtered out and
remain on top of the filter 20. The filtrand 5 can be rinsed with a
solvent to further help remove any remaining impurities that may
have not passed through the filter 20. After the CuNW dispersion 4
passes through the filter 20, the CuNW 2 in the filtrand 5 can be
scraped, dumped, and/or shaken off the filter 20 with or without a
solvent. The CuNW 2 can be re-dispersed by adding solvents
(including water, alcohol such as, for example, ethanol,
combinations thereof, and/or the like), dispersants, and/or
surfactants. In some embodiments, the CuNW dispersion can be
filtered and re-dispersed as described herein one, two, three,
four, five, or more times. The CuNW dispersion can be filtered
through the same or a different filter 20. The number of passes
through a filter 20 can affect properties of the dispersion such as
purity, concentration, and average CuNW size of the CuNW 2.
Filtering the dispersion more than one time can increase the purity
of the CuNW 2.
[0034] Before, after, and/or between washing and filtering the CuNW
dispersion 4, the CuNW 2 can optionally be deoxidized in a process
21 to remove oxidized metals on any oxidized CuNW 10. In certain
embodiments, if the metal oxide coating 16 includes CuO, the CuO
can be reduced to Cu.sub.2O by reaction with ethylene glycol and/or
the like, for example to increase removability using acid. A low
concentration acid can deoxidize oxidized CuNW 10 to remove the
oxide coating 16 and attain CuNW 2 substantially having just Cu
cores 14 after removal of the oxide coating 16, illustrated as a
cross-section showing an exploded view of a Cu core 14 in the CuNW
dispersion 7. The acid can be, for example, 0.05 M of hydrochloric
acid (HCl) mixed with an alcohol such as ethanol, isopropanol,
terpineol, and/or the like. Other acids can include, but not
limited to sulfuric acid (H.sub.2SO.sub.4), Tartaric acid, citric
acid, and/or the like. The acid should be dilute enough that a
further reduction reaction is avoided. An example cross-section of
a CuNW 14 substantially without oxidation that may be present in
the dispersion 4 is illustrated in the process 21 after
deoxidation. In some embodiments, ethanol can help inhibit or
prevent agglomeration and/or oxidation of the CuNW 2. In some
embodiments, a 50 mL mixture of the CuNW dispersion and the dilute
acid are passed through the same or different filter 20. The filter
20 can be any suitable filter that is stable for use with acids in
low concentrations.
[0035] The CuNW 2 can then be dispersed as described herein to
attain a CuNW dispersion 7 with a concentration between about 0.1
g/L and about 1 g/L, including between about 0.05 g/L and about 2
g/L, about 0.05 g/L and about 1.5 g/L, about 0.05 g/L and about 1
g/L, about 0.05 g/L and about 0.5 g/L, about 0.05 g/L and about 0.1
g/L, about 0.1 g/L and about 2 g/L, about 0.1 g/L and about 1.5
g/L, about 0.1 g/L and about 1 g/L, about 0.1 g/L and about 0.5
g/L, about 0.5 g/L and about 2 g/L, about 0.5 g/L and about 1.5
g/L, about 0.5 g/L and about 1 g/L, about 1 g/L and about 2 g/L,
about 1 g/L and about 1.5 g/L, and about 1.5 g/L and about 2 g/L,
including ranges bordering and including the foregoing values.
Solvents for adjusting concentration of the CuNW 2 in the CuNW
dispersion 7 can include water and/or organic solvents such as
ethanol, isopropanol, terpineol, ethylene glycol, dithylene glycol,
combinations thereof, others discussed herein, and/or the like.
Dispersants may also be added to the CuNW dispersion 7. The
dispersants can include polymer dispersants, for example, PVP, bile
salts, sodium docecyl sulphate, and/or others discussed herein. In
some embodiments, the CuNW dispersion 7 can include 10 .mu.L of a
10% aqueous solution of bile salts added to 50 mL of 0.2 g/L of
CuNW dispersion. The washed, filtered, deoxidized dispersion 7 with
a controlled concentration of dispersed CuNW 2 can be contained in
a beaker 8 or any other suitable container.
[0036] In certain embodiments, the following steps may be performed
to filter, wash, and deoxidize a CuNW dispersion. First, 50 mL of a
0.2 g/L CuNW dispersion is filtered through a filter. Second, the
CuNW in the filtrand 5 are dispersed in ethanol to a volume of 50
mL and filtered again through the same or a different filter.
Third, the second step is repeated 3 additional times for a total
of 4 filtrations, which can each be through the same or a different
filter. Fourth, the CuNW are deoxidized by mixing with an acid and
dispersed in ethanol to a volume of 50 mL. Concentration can vary
depending on volume of acid and ethanol used. Fifth, the 50 mL
deoxidized CuNW and acid mixture is filtered through the same or a
different filter. After each filtration, a subset of filtrations,
or an entire series of filtrations, the filter may be discarded, or
filters may be reused with other dispersions.
Fabrication of Second Nanostructures
[0037] FIG. 3 illustrates an example embodiment of a process for
mixing a dispersion including nanostructures comprising and a first
element and a reagent solution including a second element in which
the second element at least partially replaces the first element in
the nanostructures. More particularly, FIG. 3 illustrates an
example embodiment of a process for mixing a dispersion 22
including CuNW 2 and a silver reagent solution 26 to form AgNW. It
will be appreciated that a wide variety of alternatives are
commensurate with the methods described herein. For example, the
second element or silver need no be in a reagent solution, could be
added in solid form, could be an element other than silver, etc. In
some embodiments, the solution 26 including water, ionic liquids,
and/or organic solvents and silver 30 (e.g., silver nitrate (e.g.,
AgNO.sub.3 and/or Ag(NH.sub.3).sub.2NO.sub.3), ionic silver, etc.)
is slowly added to the CuNW dispersion 22 with vigorous stirring.
The silver 30 may be at a concentration between about 0.05 M and
about 0.5 M, about 0.05 M and 0.25 M, about 0.05 M and 0.2 M, about
0.05 M and 0.15 M, about 0.1 M and 0.25 M, and about 0.1 M and 0.15
M, including ranges bordering and including the foregoing values.
In some embodiments, the solution 26 is 2.1 mL of 0.113 M aqueous
AgNO.sub.3 for a 50 mL dispersion of 0.2 g/L CuNW. It will be
appreciated that the concentration of silver 30 in the solution 26
may vary based on the form of the silver 30, the process of
addition to the dispersion 22, the concentration of the CuNW 2 in
the dispersion 22, combinations thereof, and/or the like. The
solution 26 can be added using a shower device 28. The shower
device 28 can deliver the solution 26 as single drops, shower,
mist, combinations thereof, and/or the like. The solution 26 can be
added to the CuNW dispersion 22 in low concentration under
continuous vigorous stirring provided by a stirrer 29. In some
embodiments, the stirrer 29 can be magnetic, Vortex, ultrasonic,
combinations thereof, and/or any other stirring method sufficient
to rapidly and/or uniformly distribute the solution 26 in the
dispersion 22. A slow, even addition of the solution 26 can
increase uniformity of Cu replacement by Ag and/or can help inhibit
or prevent localized replacement of Cu by Ag as described herein.
Inhibiting or preventing localized replacement can reduce wasted
Ag, and thereby reduce costs, for example by reducing or minimizing
use of Ag that does not replace Cu in the desired nanowire or
nanostructure.
[0038] In certain embodiments, as the solution 26 mixes with the
CuNW dispersion 22, the silver 30 reagents in the solution 26
disperse around the CuNW 2. The Ag 30 replaces the Cu 34 in the
CuNW 2 to form AgNW. The dispersion 22 can include ions 31 such as,
for example, Cu.sup.2+, Ag.sup.+, NO.sub.3.sup.-, NH.sub.3.sup.+,
and/or the like. In some embodiments, the following reduction
reaction may occur. Because Cu 34 has a higher reactivity than Ag
30, the Cu 34 displaces Ag 30 from its nitrate group in a reduction
reaction or redox replacement reaction. Through the replacement or
displacement reaction, the Ag 30 in a silver nitrate reagent 26 can
take the place of the Cu 34 in the CuNW 2 to form AgNW. In some
embodiments, the copper may react with nitrates in the solution to
form copper nitrates. It will be appreciated that copper may have
more affinity than silver to chemicals other than nitrates (e.g.,
amines), and that reactions other than redox replacement are also
possible to replace the Cu in the CuNW with Ag to form AgNW. An
example portion (e.g., transverse cross-section) of a CuNW 2 is
shown in exploded view 32, which schematically illustrates the Ag
30 taking the place of Cu 34 in the CuNW 2 to form AgNW, while Cu
34 enters the solution. As the Cu 34 enters the solution, the Cu 34
can form Cu 34 nitrate groups such as Cu(NO.sub.3).sub.2.
[0039] Thus, the CuNW can act as a template for silver nanowires as
the Ag takes the place of Cu. Using CuNW as a template can, for
example, help control the size and shape of the AgNW. In some
embodiments, the Ag takes place of all of the Cu atoms in the CuNW
to form a AgNW that is devoid or substantially devoid of Cu. In
some embodiments, the Ag takes place of some of the Cu depending on
the desired nanowire composition or structure. For example, to
reduce costs but still achieve some benefits provided by Ag over
Cu, only a percentage of the Cu may be replaced by Ag. The
percentage may be greater than about 95%, 90%, 75%, 50%, 25%, 10%,
or 5%. In some embodiments, the resulting nanowires in films have
resistivity less than about 7.5.times.10.sup.3 .OMEGA.m in a 2.0
vol % NW/LDPE. In some embodiments, the resulting nanowires in
dispersion have transmittance greater than about 70% at a
resistance of 15 .OMEGA./sq. In certain embodiments, instead of the
silver solution 26 being slowly added to the CuNW dispersion 22,
the CuNW dispersion 22 is slowly added to the silver solution 26
with vigorous stirring by a stirrer 29 to result in the same
fabrication process of AgNW as described herein.
[0040] FIG. 4 depicts a simplified example of a process flow
diagram illustrating steps including dispersing, filtering,
deoxidizing, and/or mixing. The process can be used to fabricate
AgNW, for example as described herein. In some embodiments, at
Start 36, an initial CuNW dispersion received from the manufacturer
is filtered 38 through a filter, for example as described herein.
The CuNW filtrand is dispersed 40, for example as described herein.
The CuNW is next filtered 42 through the same or a different filter
as used in filtering step 38, for example as described herein. At
decision point 44, it is determined whether the CuNW filtrand
dispersion has the desired purity, concentration, and/or average
size of the CuNW. If not, the dispersing step 40 and filtering step
42 are repeated n times, for example as described herein, until the
desired purity, concentration, and/or average size of the CuNW is
attained. After attaining the desired purity, concentration, and/or
average size of the CuNW dispersion, or after reaching a maximum
number n of iterations, it is determined at decision point 46
whether CuNW dispersion includes oxidized CuNW. If the CuNW
dispersion may have oxidized CuNW, the CuNW are deoxidized 48, for
example as described herein. Then the deoxidized CuNW dispersion is
filtered 50 through the same or a different filter as used in
filtering steps 38, 42, and 50, for example as described herein.
The deoxidizing step 48 and filtering step 50 are optional, for
example if the CuNW are not oxidized or if oxidation of the CuNW
does not substantially impede the replacement reaction. After
deoxidizing 48 and filtering 50, or if no deoxidizing 48 or
filtering 50 is performed, the CuNW are dispersed 52, for example
as described herein. The CuNW dispersion is then mixed 54 with a Ag
solution and the mixture is vigorously stirred 54 until AgNW are
formed, for example as described herein, ending at End 56. The
steps illustrated in FIG. 4 may be rearranged, repeated, combined,
and/or omitted. For example, deoxidizing 48 and filtering 50 may be
performed before filtering 38. For another example, dispersing 40
may be omitted. For another example, dispersing 40, and filtering
42 may be omitted. For another example, dispersing 40, and
filtering 42 may be repeated zero times. For another example,
decision points 44 and 46 may be omitted, and the steps performed
without regard to decision point answers (e.g., always repeat
dispersing 40 and filtering 42 three times, always deoxidize 48 and
filter 50, never deoxidize 48 and filter 50, etc.). Many other
modifications are also possible.
[0041] In certain embodiments, the resulting AgNW dispersion can be
aqueous. In other embodiments, the AgNW dispersion can comprise
organic solvents. For example, the AgNW dispersion can include
water, ethanol, isopropanol, terpineol, ethylene glycol, dithylene
glycol, combinations thereof, and/or the like. Non-polar solvents
may also be possible. In some embodiments, the AgNW dispersion
comprises dispersants. Dispersants can include polymers such as,
for example, polyvinylpyrrolidone, polyethylene oxide,
polyoxyethylene nonylphenyl ether, polypropylene oxide,
polyoxyethylene glycol alkyl ethers, polyoxypropylene glycol alkyl
ethers, polyethoxylated tallow amine, poloxamers, polysorbate,
polymethylmetacrylic ammonium salt, polyacrylic ammonium salt,
polyacrylic amine salt, polyacrylic sodium salt, gum Arabic,
combinations thereof, and/or the like. In some embodiments, the
AgNW dispersion can comprise surfactants. Surfactants can include,
for example, sodium lauryl ether sulfate, sodium myreth sulfate,
ammonium lauryl sulfate, sodium dodecyl sulfate, alkyl aryl ether
phosphate, alkyl ether phosphate, perfluorooctanesulfonate,
perfluorobutanesulfonate, dioctyl sodium sulfosuccinate, alkyl
benzene sulfonates, sodium stearate, sodium lauryl sarcosinate,
perfluorononanoate, perfluorooctanoate, dimethyldioctadecylammonium
chloride, dioctadecyldimethylammonium bromide, octenidine
dihydrochloride, cetyl trimethylammonium bromide, cetyl
trimethylammonium chloride, cetylpyridinium chloride, benzalkonium
chloride, benzethonium chloride, 5-bromo-5-nitro-1,3-dioxane,
3-[(3-Cholamidopropyl)dimethylammonio]-1-propanesulfonate,
zwitterionic detergents, cocamidopropyl hydroxysultaine,
cocamidopropyl betaine, imino acids, amino acids, lecithin, cetyl
alcohol, stearyl alcohol, cetostearyl alcohol, oleyl alcohol,
octaethylene glycol monododecyl ether, pentaethylene glycol
monododecyl ether, decyl glucoside, lauryl glucoside, octyl
glucoside, Triton X-100, Nonoxynol-9, Daxad 19, glyceryl laurate,
dodecyldimethylamine oxide, cocamide MEA, cocamide DEA, spans,
combinations thereof, and/or the like. Dispersants can help inhibit
or prevent agglomeration of a AgNW dispersion. Surfactants can act
as dispersants, dispersants can act as surfactants, and certain
solvents, for example in combination with other solvents, may act
as dispersants and/or surfactants in a AgNW dispersion.
Accordingly, any of the compositions discussed herein may be
considered a solvent, a dispersant, or a surfactant depending on
context.
[0042] FIG. 5 depicts an example plot of resistance versus
transmissivity for an example embodiment of a AgNW mesh and/or ink.
In some embodiments, the AgNW mesh and/or ink can include nanowires
having a diameter between about 75 nm and about 105 nm and a length
between about 30 .mu.m and about 40 .mu.m. Plot line 60 shows test
data for resistance versus transmissivity obtained with the example
embodiment AgNW mesh and/or ink. The predicted plot line 58 can be
a line fit to the plot line 60 using a mathematical model that can
characterize performance of a AgNW mesh and/or ink. The predicted
plot line 58 can be used to predict the transmissivity of a AgNW
mesh and/or ink at a given resistance. The predicted plot line 58
can be used to predict the resistance of a AgNW mesh and/or ink at
a given transmissivity. As illustrated in FIG. 5, the AgNW mesh
and/or ink can have a transmissivity between about 92% and about
93% at 15 .OMEGA./sq. When the AgNW mesh and/or ink is applied to a
substrate, the transmissivity of the substrate can decrease the
overall transmissivity of the AgNW coated substrate. For example, a
polyethylene terephthalate (PET) substrate can have a
transmissivity between about 88% and about 90%. When the AgNW mesh
and/or ink of FIG. 5 is applied onto the PET substrate, the overall
transmissivity of the AgNW coated PET substrate can be between
about 80% (88%.times.92%) and about 84% (90%.times.93%) at 15
.OMEGA./sq.
[0043] Transmittance of a mesh or film on a substrate may be
reported at the total transmittance of the mesh or film and
substrate. In such cases, the transmittance of the mesh or film can
be determined by dividing the reported transmittance by the
transmittance of the substrate. For example, if transmittance of a
mesh or film including a PET substrate is reported at 83% (e.g., at
a resistance of 15 .OMEGA./sq), then the transmittance of the mesh
or film without the substrate would be between about 92% (83%/90%)
and about 94% (83%/88%) at that resistance.
[0044] The transmittance of AgNW in a mesh or ink and the
resistance of AgNW in the mesh or ink may be related, and the
transmittance of AgNW in a mesh or ink and the conductivity of AgNW
in the mesh or ink may be inversely related. For example, when a
AgNW mesh or ink has a low resistance, the mesh or ink generally
includes a larger proportion of AgNW such that the mesh or ink is
able to conduct electric signals with less resistance, but that
same larger proportion of AgNW may cause the mesh or ink to reflect
more incident light, reducing transmittance of the mesh or ink.
AgNW in a mesh or ink and having a higher resistivity than 15
.OMEGA./sq may have higher transmittance, for example greater than
about 92% or greater than about 93%. AgNW in a mesh or ink and
having a lower resistivity than 15 .OMEGA./sq may have lower
transmittance, for example less than about 92% or less than about
93%, but that transmittance would still be higher than CuNW in the
mesh or ink at the same resistivity. Factors such as AgNW
dimensions, uniformity of the AgNW, etc. may also influence
conductivity and/or transmittance.
[0045] In certain the embodiments, the AgNW dispersion can be used
in conductive inks and polymers for applications such as, for
example, electrical devices, displays or screens, solar panels,
and/or the like. The AgNW formed by the above technique can be
employed in other conductive ink and polymer applications as
described in the '999 application, the entire disclosure of which
is incorporated herein by reference and appended.
[0046] The following is a list of example embodiments:
[0047] 1. A method comprising: [0048] mixing a dispersion and a
reagent solution, the dispersion including nanostructures
comprising a first element, the reagent solution including a second
element, the second element at least partially replacing the first
element in the nano structures.
[0049] 2. The method of Embodiment 1, wherein the nanostructures
comprise nanowires.
[0050] 3. The method of Embodiment 1 or 2, wherein the first
element is copper.
[0051] 4. The method of any of Embodiments 1-3, wherein the second
element is silver.
[0052] 5. The method of any of Embodiments 1-4, wherein a
concentration of the nanostructures in the dispersion is between
about 0.1 g/L and about 1 g/L.
[0053] 6. The method of any of Embodiments 1-5, wherein the
dispersion includes at least one of dispersants and
surfactants.
[0054] 7. The method of any of Embodiments 1-6, wherein the
dispersion includes polyvinylpyrrolidone.
[0055] 8. The method of any of Embodiments 1-7, wherein the
dispersion includes bile salts.
[0056] 9. The method of any of Embodiments 1-8, wherein the
dispersion includes water.
[0057] 10. The method of any of Embodiments 1-9, wherein the
dispersion includes organic solvent.
[0058] 11. The method of Embodiment 10, wherein the organic solvent
comprises ethanol.
[0059] 12. The method of any of Embodiments 1-11, wherein a
concentration of the reagent solution is between about 0.1 M and
about 0.15 M.
[0060] 13. The method of any of Embodiments 1-12, wherein the
reagent solution comprises a silver nitrate.
[0061] 14. The method of any of Embodiments 1-13, wherein the
reagent solution comprises silver ions.
[0062] 15. The method of any of Embodiments 1-14, mixing comprises
slowly adding the reagent solution.
[0063] 16. The method of Embodiment 15, wherein slowly adding
comprises drop-wise adding.
[0064] 17. The method of any of Embodiments 1-16, wherein mixing
comprises vigorously stirring with a stirrer.
[0065] 18. The method of Embodiment 17, wherein the stirrer
comprises a magnetic stirrer.
[0066] 19. The method of any of Embodiments 1-18, wherein the
second element partially replaces the first element in the
nanostructures.
[0067] 20. The method of Embodiment 19, wherein the second element
replaces at least about 5% of the first element in the
nanostructures.
[0068] 21. The method of Embodiment 19, wherein the second element
replaces at least about 10% of the first element in the
nanostructures.
[0069] 22. The method of Embodiment 19, wherein the second element
replaces at least about 25% of the first element in the
nanostructures.
[0070] 23. The method of Embodiment 19, wherein the second element
replaces at least about 50% of the first element in the
nanostructures.
[0071] 24. The method of Embodiment 19, wherein the second element
replaces at least about 75% of the first element in the
nanostructures.
[0072] 25. The method of Embodiment 19, wherein the second element
replaces at least about 90% of the first element in the
nanostructures.
[0073] 26. The method of Embodiment 19, wherein the second element
replaces at least about 95% of the first element in the
nanostructures.
[0074] 27. The method of any of Embodiments 1-18, wherein the
second element substantially fully replaces the first element in
the nanostructures.
[0075] 28. The method of any of Embodiments 1-27, wherein, after
mixing, the nanostructures in films have a resistivity less than
about 7.5.times.10.sup.3 .OMEGA.m in a 2.0 vol % nanostructures/low
density polyethylene.
[0076] 29. The method of any of Embodiments 1-28, wherein, after
mixing, the nanostructures in dispersion have a visible light
transmittance greater than about 70% at a resistance of 15
.OMEGA./sq.
[0077] 30. The method of any of Embodiments 1-29, further
comprising, before mixing, filtering the nano structures.
[0078] 31. The method of Embodiment 30, wherein filtering the
nanostructures includes using a non-fibrous filter.
[0079] 32. The method of Embodiment 31, wherein the filter includes
pores having a size of about 0.2 microns or less.
[0080] 33. The method of Embodiment 31 or 32, wherein the filter
comprises Teflon.
[0081] 34. The method of any of Embodiments 30-33, further
comprising dispersing the nanostructures in a solvent.
[0082] 35. The method of Embodiment 34, wherein the solvent
includes water.
[0083] 36. The method of Embodiments 34 or 35, wherein the solvent
includes organic solvent.
[0084] 37. The method of Embodiment 36, wherein the organic solvent
comprises ethanol.
[0085] 38. The method of any of Embodiments 34-37, wherein the
solvent includes at least one of dispersants and surfactants.
[0086] 39. The method of Embodiment 38, wherein the solvent
includes polyvinylpyrrolidone.
[0087] 40. The method of Embodiment 38 or 39, wherein the solvent
includes bile salts.
[0088] 41. The method of any of Embodiments 1-40, further
comprising deoxidizing the nano structures.
[0089] 42. The method of Embodiment 41, wherein deoxidizing
comprises mixing an acid and a first dispersion including oxidized
nanostructures.
[0090] 43. The method of Embodiment 42, wherein the acid comprises
about 0.05 M HCl.
[0091] 44. The method of Embodiment 42 or 43, further comprising
filtering the mixed acid and first dispersion through a filter.
[0092] 45. The method of Embodiment 44, wherein the filter is a
non-fibrous filter.
[0093] 46. The method of Embodiment 44 or 45, wherein the filter
includes pores having a size of about 0.2 microns or less.
[0094] 47. The method of any of Embodiments 44-46, wherein the
filter is stable with acids in low concentrations.
[0095] 48. The method of any of Embodiments 44-47, wherein the
filter comprises Teflon.
[0096] 49. The method of any of Embodiments 41-48, further
comprising dispersing the deoxidized nanostructures in a
solvent.
[0097] 50. The method of Embodiment 49, wherein the solvent
includes water.
[0098] 51. The method of Embodiments 49 or 50, wherein the solvent
includes organic solvent.
[0099] 52. The method of Embodiment 51, wherein the organic solvent
comprises ethanol.
[0100] 53. The method of any of Embodiments 49-52, wherein the
solvent includes at least one of dispersants and surfactants.
[0101] 54. The method of Embodiment 53, wherein the solvent
includes polyvinylpyrrolidone.
[0102] 55. The method of Embodiment 53 or 54, wherein the solvent
includes bile salts.
[0103] 56. The method of any of Embodiments 1-55, further
comprising, after mixing, adding the nanostructures to an ink.
[0104] 57. The method of Embodiment 56, further comprising printing
the ink to form a transparent conductive portion of a device.
[0105] 58. The method of Embodiment 57, wherein the device
comprises a solar device.
[0106] 59. The method of Embodiment 57, wherein the device
comprises a display.
[0107] 60. A system for performing the method of any of Embodiments
1-59.
[0108] 61. A method comprising: [0109] filtering a dispersion
including nanostructures.
[0110] 62. The method of Embodiment 61, wherein the nanostructures
comprise nanowires.
[0111] 63. The method of Embodiment 61 or 62, wherein the
nanostructures comprise copper.
[0112] 64. The method of any of Embodiments 61-63, wherein, after
filtering, a concentration of the nanostructures in the dispersion
is between about 0.1 g/L and about 1 g/L.
[0113] 65. The method of any of Embodiments 61-64, wherein the
dispersion includes at least one of dispersants and
surfactants.
[0114] 66. The method of any of Embodiments 61-65, wherein the
dispersion includes polyvinylpyrrolidone.
[0115] 67. The method of any of Embodiments 61-66, wherein the
dispersion includes bile salts.
[0116] 68. The method of any of Embodiments 61-67, wherein the
dispersion includes water.
[0117] 69. The method of any of Embodiments 61-68, wherein the
dispersion includes organic solvent.
[0118] 70. The method of Embodiment 69, wherein the organic solvent
comprises ethanol.
[0119] 71. The method of any of Embodiments 61-70, wherein
filtering the nanostructures includes using a non-fibrous
filter.
[0120] 72. The method of Embodiment 71, wherein the filter includes
pores having a size of about 0.2 microns or less.
[0121] 73. The method of Embodiment 71 or 72, wherein the filter
comprises Teflon.
[0122] 74. The method of any of Embodiments 61-73, further
comprising dispersing the nanostructures in a solvent.
[0123] 75. The method of Embodiment 74, wherein the solvent
includes water.
[0124] 76. The method of Embodiments 74 or 75, wherein the solvent
includes organic solvent.
[0125] 77. The method of Embodiment 76, wherein the organic solvent
comprises ethanol.
[0126] 78. The method of any of Embodiments 74-77, wherein the
solvent includes at least one of dispersants and surfactants.
[0127] 79. The method of Embodiment 78, wherein the solvent
includes polyvinylpyrrolidone.
[0128] 80. The method of Embodiment 78 or 79, wherein the solvent
includes bile salts.
[0129] 81. The method of any of Embodiments 61-80, further
comprising deoxidizing the nano structures.
[0130] 82. The method of Embodiment 81, wherein deoxidizing
comprises mixing an acid and a first dispersion including oxidized
nanostructures.
[0131] 83. The method of Embodiment 82, wherein the acid comprises
about 0.05 M HCl.
[0132] 84. The method of Embodiment 82 or 83, further comprising
filtering the mixed acid and first dispersion through a filter.
[0133] 85. The method of Embodiment 84, wherein the filter is a
non-fibrous filter.
[0134] 86. The method of Embodiment 84 or 85, wherein the filter
includes pores having a size of about 0.2 microns or less.
[0135] 87. The method of any of Embodiments 84-86, wherein the
filter is stable with acids in low concentrations.
[0136] 88. The method of any of Embodiments 84-87, wherein the
filter comprises Teflon.
[0137] 89. The method of any of Embodiments 81-88, further
comprising dispersing the deoxidized nanostructures in a
solvent.
[0138] 90. The method of Embodiment 89, wherein the solvent
includes water.
[0139] 91. The method of Embodiments 89 or 90, wherein the solvent
includes organic solvent.
[0140] 92. The method of Embodiment 91, wherein the organic solvent
comprises ethanol.
[0141] 93. The method of any of Embodiments 89-92, wherein the
solvent includes at least one of dispersants and surfactants.
[0142] 94. The method of Embodiment 93, wherein the solvent
includes polyvinylpyrrolidone.
[0143] 95. The method of Embodiment 93 or 94, wherein the solvent
includes bile salts.
[0144] 96. A system for performing the method of any of Embodiments
61-95.
[0145] 97. A dispersion comprising: [0146] a solvent; and [0147]
nanowires comprising silver and having a length greater than about
10 microns in a dimension, the nanowires dispersed in the
solvent.
[0148] 98. The dispersion of Embodiment 97, wherein the length is
greater than about 25 microns in the dimension.
[0149] 99. The dispersion of Embodiment 97 or 98, wherein the
length is greater than about 50 microns in the dimension.
[0150] 100. The dispersion of any of Embodiments 97-99, wherein the
length is greater than about 70 microns in the dimension.
[0151] 101. The dispersion of any of Embodiments 97-100, wherein
the length is less than about 150 microns in the dimension.
[0152] 102. The dispersion of Embodiment 97, wherein the length is
between about 10 microns and about 150 microns in the
dimension.
[0153] 103. The dispersion of Embodiment 97 or 102, wherein the
length is between about 25 microns and about 150 microns in the
dimension.
[0154] 104. The dispersion of any of Embodiments 97, 102, and 103,
wherein the length is between about 50 microns and about 150
microns in the dimension
[0155] 105. The dispersion of any of Embodiments 97 and 102-104,
wherein the length is between about 70 microns and about 150
microns in the dimension.
[0156] 106. The dispersion of any of Embodiments 97-105, wherein
the nanowires comprise at least about 5% silver.
[0157] 107. The dispersion of any of Embodiments 97-106, wherein
the nanowires comprise less than about 95% copper.
[0158] 108. The dispersion of any of Embodiments 97-107, wherein
the nanowires comprise at least about 10% silver.
[0159] 109. The dispersion of any of Embodiments 97-108, wherein
the nanowires comprise less than about 90% copper.
[0160] 110. The dispersion of any of Embodiments 97-109, wherein
the nanowires comprise at least about 25% silver.
[0161] 111. The dispersion of any of Embodiments 97-110, wherein
the nanowires comprise less than about 75% copper.
[0162] 112. The dispersion of any of Embodiments 97-111, wherein
the nanowires comprise at least about 50% silver.
[0163] 113. The dispersion of any of Embodiments 97-112, wherein
the nanowires comprise less than about 50% copper.
[0164] 114. The dispersion of any of Embodiments 97-113, wherein
the nanowires comprise at least about 75% silver.
[0165] 115. The dispersion of any of Embodiments 97-114, wherein
the nanowires comprise less than about 25% copper.
[0166] 116. The dispersion of any of Embodiments 97-115, wherein
the nanowires comprise at least about 90% silver.
[0167] 117. The dispersion of any of Embodiments 97-116, wherein
the nanowires comprise less than about 10% copper.
[0168] 118. The dispersion of any of Embodiments 97-117, wherein
the nanowires comprise at least about 95% silver.
[0169] 119. The dispersion of any of Embodiments 97-118, wherein
the nanowires comprise less than about 5% copper.
[0170] 120. The dispersion of any of Embodiments 97-119, wherein
the nanowires comprise about 100% silver.
[0171] 121. The dispersion of any of Embodiments 97-120, wherein
the nanowires comprise substantially no copper.
[0172] 122. The dispersion of any of Embodiments 97-121, wherein
the nanowires in films have a resistivity less than about
7.5.times.10.sup.3 .OMEGA.m in a 2.0 vol % nanowires/low density
polyethylene.
[0173] 123. The dispersion of any of Embodiments 97-122, wherein
the nanowires in dispersion have a visible light transmittance
greater than about 70% at a resistance of 15 .OMEGA./sq.
[0174] 124. The dispersion of any of Embodiments 97-123, wherein a
concentration of the nanowires is between about 0.1 g/L and about 1
g/L.
[0175] 125. The dispersion of any of Embodiments 97-124, wherein
the solvent includes water.
[0176] 126. The dispersion of any of Embodiments 97-125, wherein
the solvent includes organic solvent.
[0177] 127. The dispersion of Embodiment 126, wherein the organic
solvent comprises ethanol.
[0178] 128. The dispersion of any of Embodiments 97-127, wherein
the solvent includes at least one of dispersants and
surfactants.
[0179] 129. The dispersion of Embodiment 128, wherein the solvent
includes polyvinylpyrrolidone.
[0180] 130. The dispersion of Embodiment 128 or 129, wherein the
solvent includes bile salts.
[0181] 131. A conductive ink comprising the dispersion of any of
Embodiments 97-130.
[0182] 132. A device comprising the conductive ink of Embodiment
131.
[0183] 133. The device of Embodiment 132, wherein the device
comprises a solar device.
[0184] 134. The device of Embodiment 132, wherein the device
comprises a display.
[0185] The foregoing detailed description has set forth various
embodiments of the systems and/or methods via the use of figures
and/or examples. Insofar as such figures and/or examples contain
one or more functions and/or operations, it will be understood by
those within the art that each function and/or operation within
figures or examples can be implemented individually and/or
collectively. The herein-described subject matter sometimes
illustrates different components contained within, or connected
with, different other components. It is to be understood that such
depicted architectures are merely examples, and that in fact many
other architectures can be implemented which achieve the same
functionality. In a conceptual sense, any arrangement of components
to achieve the same functionality is effectively "associated" such
that the desired functionality is achieved. Hence, any two
components herein combined to achieve a particular functionality
can be seen as "associated with" each other such that the desired
functionality is achieved, irrespective of architectures or
intermedial components.
[0186] With respect to the use of substantially any plural and/or
singular terms herein, those having skill in the art can translate
from the plural to the singular and/or from the singular to the
plural as is appropriate to the context and/or application. The
various singular/plural permutations may be expressly set forth
herein for sake of clarity.
[0187] It will be understood by those within the art that, in
general, terms used herein, and especially in the appended Certain
Embodiments (e.g., bodies of the appended Certain Embodiments) are
generally intended as "open" terms (e.g., the term "including"
should be interpreted as "including but not limited to," the term
"having" should be interpreted as "having at least," the term
"includes" should be interpreted as "includes but is not limited
to," etc.). It will be further understood by those within the art
that if a specific number of an introduced embodiment recitation is
intended, such an intent will be explicitly recited in the
embodiment, and in the absence of such recitation no such intent is
present. For example, as an aid to understanding, the following
appended Certain Embodiments may contain usage of the introductory
phrases "at least one" and "one or more" to introduce embodiment
recitations. However, the use of such phrases should not be
construed to imply that the introduction of an embodiment
recitation by the indefinite articles "a" or "an" limits any
particular embodiment containing such introduced embodiment
recitation to embodiments containing only one such recitation, even
when the same embodiment includes the introductory phrases "one or
more" or "at least one" and indefinite articles such as "a" or "an"
(e.g., "a" and/or "an" should typically be interpreted to mean "at
least one" or "one or more"); the same holds true for the use of
definite articles used to introduce embodiment recitations. In
addition, even if a specific number of an introduced embodiment
recitation is explicitly recited, those skilled in the art will
recognize that such recitation should typically be interpreted to
mean at least the recited number (e.g., the bare recitation of "two
recitations," without other modifiers, typically means at least two
recitations, or two or more recitations). Furthermore, in those
instances where a convention analogous to "at least one of A, B,
and C, etc." is used, in general such a construction is intended in
the sense one having skill in the art would understand the
convention (e.g., "a system having at least one of A, B, and C"
would include but not be limited to systems that have A alone, B
alone, C alone, A and B together, A and C together, B and C
together, and/or A, B, and C together, etc.). In those instances
where a convention analogous to "at least one of A, B, or C, etc."
is used, in general such a construction is intended in the sense
one having skill in the art would understand the convention (e.g.,
"a system having at least one of A, B, or C" would include but not
be limited to systems that have A alone, B alone, C alone, A and B
together, A and C together, B and C together, and/or A, B, and C
together, etc.). It will be further understood by those within the
art that virtually any disjunctive word and/or phrase presenting
two or more alternative terms, whether in the description,
embodiments, or drawings, should be understood to contemplate the
possibilities of including one of the terms, either of the terms,
or both terms. For example, the phrase "A or B" will be understood
to include the possibilities of "A" or "B" or "A and B."
[0188] While various aspects and embodiments have been disclosed
herein, other aspects and embodiments will be apparent to those
skilled in the art. The various aspects and embodiments disclosed
herein are for purposes of illustration and are not intended to be
limiting.
* * * * *