WO2020038641A1 - Films électroconducteurs transparents et encre pour leur production - Google Patents

Films électroconducteurs transparents et encre pour leur production Download PDF

Info

Publication number
WO2020038641A1
WO2020038641A1 PCT/EP2019/067867 EP2019067867W WO2020038641A1 WO 2020038641 A1 WO2020038641 A1 WO 2020038641A1 EP 2019067867 W EP2019067867 W EP 2019067867W WO 2020038641 A1 WO2020038641 A1 WO 2020038641A1
Authority
WO
WIPO (PCT)
Prior art keywords
metal
substrate
nanoobjects
metal nanoobjects
carrier liquid
Prior art date
Application number
PCT/EP2019/067867
Other languages
English (en)
Inventor
Elisabeth KUTTNER
Galen Stucky
Fengru Fan
Yang Zhao
Linye CHEN
Binghui Wu
Original Assignee
Basf Se
The Regents Of The University Of California
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Basf Se, The Regents Of The University Of California filed Critical Basf Se
Publication of WO2020038641A1 publication Critical patent/WO2020038641A1/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/10—Metal compounds
    • C08K3/11—Compounds containing metals of Groups 4 to 10 or of Groups 14 to 16 of the Periodic Table
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/16—Halogen-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
    • C08L33/08—Homopolymers or copolymers of acrylic acid esters
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/52—Electrically conductive inks
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/011—Nanostructured additives

Definitions

  • the present invention relates to a composition suitable for the preparation of an electro- conductive transparent film, a method for preparing said composition, the use of said composition, an article comprising an electroconductive transparent film, the use of said article and a method for preparing such an article.
  • Metal nanoobjects, especially metal nanowires, such as silver nanowires are commonly used for preparing transparent electroconductive films.
  • transparent electroconductive film refers to a film which (i) is capable of allowing the flow of an electric current when an appropriate voltage is applied and (ii) has a light transmittance of 80 % or more in the visible region (400-700 nm) measured according to ASTM D1003, see e.g. US 8,049,333.
  • said film is arranged on the surface of a substrate, wherein said substrate is typically an electrical insulator and has a light transmittance at least as high as the transparent electroconductive film.
  • electroconductive transparent films are widely used in displays, touch panels, electroluminescent devices, organic light emitting diodes, thin film photovoltaic cells, as anti-static layers and as electromagnetic wave shield- ing layers.
  • electroconductive transparent films are prepared by means of wet-pro- cessing-techniques.
  • a suspension (commonly referred to as an ink) comprising metal nanoobjects dispersed in a carrier liquid is applied to the surface of the substrate by means of a wet processing technique, thereby forming a wet film on said surface, and the carrier liquid is then removed from said wet film, so that an electroconductive transparent film comprising metal nanoobjects is formed on the surface of the substrate.
  • an electroconductive transparent film comprising metal nanoobjects is formed on the surface of the substrate. Due to the small dimensions of the metal nanoobjects, their influence on the optical behavior of the film is minor, thus allowing for the formation of a film which is optically transparent and electroconductive.
  • metal nanoobjects like silver nanowires are very sensitive to chemical and thermal deterioration, due to their substantially increased specific surface area compared to the corresponding bulk metal. Oxidation, thermal break-up and aggregation of the metal nanoobjects usually results in a remarkable degradation of the electroconductivity as well as of the optical properties of electroconductive transparent films comprising such metal nanoobjects.
  • metal nanoobjects may be exposed to temperatures of 350 °C or more. Furthermore, during its use a transparent electroconductive film may be exposed to thermal and oxidative stress from the environment. High current densities as well as electrostatic discharges, which may occur during the use of transparent electroconductive films, may lead to thermal break-up and aggregation and/or oxidation of the metal nanoobjects, due to the released heat.
  • US 2014/0020737 A1 proposes a device comprising a substrate, silver nanowires disposed on the substrate, and an oxidation protection layer coated on the silver nanowires, wherein the oxidation protection layer comprises an oxide.
  • the oxidation protection layer is applied by means of an atomic layer deposition (ALD) process.
  • the oxide is a metal oxide or a metalloid oxide comprising at least one selected from the group consisting of Ti, V, Ni, Cu, Zn, Zr, Nb, Y, Al, Si, Sn, and In. Protection layers consisting of titanium dioxide Ti0 2 are preferred.
  • Atomic layer deposition (ALD) is a vacuum technique requiring a specific, expensive technical equipment.
  • Vacuum techniques cannot easily be integrated in a continuous process (e.g. a roll-to-roll-process) for preparing transparent electroconductive conductive films. Indeed, applying an oxidation protection layer by means of atomic layer deposition has to be performed as an additional treatment step after the metal nanoobjects to be protected are disposed on the substrate.
  • oxidation protection for metal nanoobjects by means of wet-pro- cessing which can be combined with the stages of preparation of the metal nanoobjects and preparation of the ink. Furthermore, it would be desirable to provide inks comprising metal nanoobjects which are protected against oxidation, so that no additional oxidation protection treatment step after the metal nanoobjects are disposed on the substrate is necessary.
  • composition comprising
  • Sn(ll) compounds are selected from Sn(ll) compounds which are solu- ble in an identical carrier liquid (A) which has no metal nanoobjects dispersed therein with the proviso that said layer does not comprise any of SnCh, SnBr 2 and Snh.
  • a composition according to the invention (as defined above) is also referred to as an ink.
  • the ink according to the present invention enables obtaining electroconductive transparent films comprising metal nanoobjects disposed on the surface of a substrate, wherein the metal nanoobjects have increased stability against oxidation, thermal stress and reactive chemicals, thereby avoiding excessive degradation of the electroconductivity as well as of the optical properties of the electroconductive transparent film. Furthermore, preparation of articles comprising transparent electroconductive films which have increased stability against oxidation, thermal stress and reactive chemi- cals is alleviated by using the ink according to the present invention, because there is no need to apply a protective coating in a separate step, as it is the case in the disclosure of US 2014/0020737 A1.
  • said metal nanoobjects (B) are selected from the group consisting of metal nanowires, metal nanoparticles, metal nanorods, metal nanofibers, metal nanoflakes, metal nanoplates and metal nanoribbons and mixtures thereof.
  • the term“nanoobject” refers to an object having one, two or three external dimensions in the nanoscale, i.e. one, two or three external dimensions in the size range of from approximately 1 nm to 100 nm.
  • nanoobjects having one external dimension in the na- noscale, while the other two external dimensions are significantly larger are generally referred to as nanoplates.
  • Said one external dimension in the nanoscale corresponds to the thickness of the nanoplate.
  • the two significantly larger dimensions differ from the nanoscale dimension by more than three times.
  • the two larger external dimensions are not necessarily in the nanoscale.
  • Another common term for denoting a nanoobject having one external dimension in the nanoscale, while the other two external dimensions are significantly larger, is“nanoflake”.
  • nanoobjects having two similar external dimensions in the nanoscale, while the third external dimension is significantly larger are generally referred to as nanofibers.
  • the third significantly larger dimension differs from the nanoscale dimensions by more than three times.
  • the largest external dimension is not necessarily in the nanoscale. Said largest external dimension corresponds to the length of the nanofibers.
  • Nanofibers typically have a cross section close to circular shape. Said cross section extends perpendicularly to the length. Thus, said two external dimensions which are in the nanoscale are defined by the diameter of said circular cross section.
  • Electrically conductive nanofibers are also referred to as nanowires. Hollow nanofibers (irrespective of their electrical conductivity) are also referred to as nanotubes.
  • Nanoobjects having two similar external dimensions in the nanoscale, while the third external dimension (length) is signifi- cantly larger, which are rigid (i.e. not flexible) are commonly referred to as nanorods.
  • Nanoobjects having two similar external dimensions in the nanoscale, while the third external dimension (length) is significantly larger, and have a cross section close to rectangular shape extending perpendicularly to the length, are commonly referred to as nanoribbons.
  • nanoobjects having all three external dimensions in the nanoscale wherein the length of the longest axis and the length of the shortest axis of the nanoobject differ by not more than three times, are generally referred to as nanoparticles.
  • Approximately isometric nanoparticles, i.e. the aspect ratio (longest : shortest direction) of all three orthogonal external dimensions is close to 1 are commonly referred to as nanospheres.
  • metal nanoobject means that the nanoobject comprises or consists of one or more materials selected from the group consisting of metals and alloys of metals.
  • a plurality of such metal nanoobjects disposed on a surface of a substrate may form a conductive network consisting of adjacent and overlapping nanoobjects capable of carrying an electric current, provided that there is suf- ficient interconnection (mutual contact) between individual metal nanoobjects so as to enable the transport of electrons along the interconnected metal nanoobjects within the network.
  • said metal nanoobjects comprise or consist of one or more metals selected from the group consisting of silver, copper, nickel, gold, palladium, tungsten, iron, cobalt and tin and alloys of two or more of said metals.
  • metal nanoobjects are metal nanoflakes and metal nanowires, preferably from the group consisting of silver nanowires and copper nanowires.
  • said metal nanoobjects are metal nanowires, preferably metal nanowires having a length of from 10 pm to 100 pm and a diameter in the range of from 10 to 200 nm. Length and diameter of metal nanowires are determined by means of one of scanning electron microscopy and transmission electron microscopy, preferably transmission electron microscopy.
  • said metal nanowires comprise or consist of one or more metals selected from the group consisting of silver, copper, nickel, gold, palladium, tungsten, iron, cobalt and tin and alloys of two or more of said metals.
  • silver nanowires and copper nanowires having a length of from 10 pm to 100 pm and a diameter in the range of from 10 to 200 nm, in each case measured by means of one of scanning electron microscopy and transmission electron microscopy, preferably transmission elec- tron microscopy.
  • the concentration of said metal nanoobjects (B) as defined above is in the range of from 0.001 wt.% to 10 wt.%, preferably 0.001 to 5 wt.%, most preferably 0.002 to 1 wt.% based on the total weight of the composition.
  • the weight fraction of the metal nanoobjects (B) is too high the metal nanoobjects are not well dispersed in the ink.
  • the weight fraction of the metal nanoobjects (B) When the weight fraction of the metal nanoobjects (B) is too low, the amount of metal nanoobjects deposited per unit of substrate surface area may be not sufficient for forming an interconnected conductive network, so that such ink is not suitable for preparing an electroconductive film. Moreover, when the weight fraction of metal nanoobjects (B) in the ink is low, the amount of carrier liquid (A) which has to be removed in the process of forming a transparent electroconduc- tive film is relatively large in relation to the amount of deposited metal nanoobjects, and processing may become inefficient.
  • the Sn(ll) compounds as defined above as well as any matter adsorbed on the surface of the metal nanoobjects (B) is not included in the above-defined dimensions of the metal nanoobjects (B) and in the weight fraction of the metal nanoobjects (B) relative to the weight of the composition according to the invention.
  • the surfaces of said dispersed metal nanoobjects are at least partially coated with a layer comprising one or more Sn(ll) compounds.
  • Sn(ll) compound denotes a compound which comprises Sn having the oxidation state +2.
  • metal nanoobjects having a coating comprising Sn0 2 (Sn(IV)oxide) and no Sn in the oxidation state +2 are not metal nanoobjects (B) as defined above.
  • the coating of the metal nanoobjects in the composition according to the invention comprises Sn in the oxidation state +4 beside Sn in the oxidation state +2.
  • Said Sn(ll) compounds are selected from Sn(ll) compounds which are soluble in an identical carrier liquid (A) which has no metal nanoobjects dispersed therein.
  • Said Sn(ll) compound is not selected from the group consisting of SnCh, SnBr2 and Snh.
  • a Sn(ll) compound is considered as soluble in a carrier liquid (A) selected from non-aque- ous polar liquids which has no metal nanoobjects dispersed therein, when it is possible to obtain a solution comprising at least 0.001 wt.% of the Sn(ll) compound dissolved in said carrier liquid (A), based on the total weight of the carrier liquid (A) and the dissolved Sn(ll) compound, where no metal nanoobjects are dispersed in the carrier liquid (A).
  • said Sn(ll) compound(s) is/are preferably present in such amount, that the ratio of the total weight of Sn(ll) in the Sn(ll) compound(s) relative to the weight of the metal nanoobjects (B) (not including the Sn(ll) compound) is in the range of from 0.01 % to 5 %, more preferably of from 0.01 % to 3.9 %, further preferably of from 0.1 % to 3.9 %, still further preferably of from 1 % to 3.9 %, most preferably in the range of from 2.0 % to 2.5 %.
  • the weight of Sn(ll) relative to the weight of the metal nanoobjects (B) in the ink is too low, coating of the surfaces of the metal nanoobjects (B) by the Sn(ll) compound(s) may be not sufficient to achieve the desired protection against thermal and oxidative stress and against reactive chemicals. If the weight of Sn(ll) relative to the weight of the metal nanoobjects (B) in the ink is too high, the coating of the surfaces of the metal nanoobjects by the Sn(ll) compound(s) may become too thick, so that the sheet resistance of a transparent conductive film obtained using such ink may be undesirably high.
  • the presence of the Sn(ll) compound in the composition according to the invention irrespective of its anion is effective in increasing the stability of metal nanoobjects (B) in transparent electroconductive films prepared using a composition according to the invention against oxidation, thermal stress and reactive chemicals, provided that the Sn(ll) compound meets the above-defined criteria, i.e. is soluble in an identical carrier liquid (A) which has no metal nanoobjects dispersed therein and is not selected from the group consisting of SnCh, SnBr2 and Snh.
  • A identical carrier liquid
  • said Sn(ll) compounds are selected from the group consisting of Sn(ll) 2-ethylhexanoate, SnF2, Sn(ll) acetylacetonate and Sn(ll) methanesulfonate.
  • a composition according to the invention comprises a carrier liquid (A).
  • the carrier liquid (A) is merely a vehicle for wet processing and does not remain in the transparent electro- conductive film to be formed from the above-defined composition.
  • the transparent electro- conductive film is formed from those constituents of the ink which at 25 °C and 101.325 kPa are solid (herein referred to as solid constituents of the ink).
  • the solid constituents of the ink comprise at least the metal nanoobjects (B). For optional further solid constituents, see below.
  • the carrier liquid (A) is selected from non-aqueous polar liquids. This applies for instance to the Sn(ll) compounds Sn(ll) 2-ethylhexanoate, SnF ⁇ and Sn(ll) acetylacetonate. Accordingly, in this case it is preferred that the composition according to the invention contains water in an amount of less than 2 wt.-%, or less than 0.5 wt.%, or less than 0.05 %, preferably less than 0.02 wt.% of water, based on the weight of the carrier liquid (A).
  • the carrier liquid (A) may be in the form of a mixture of a non-aqueous polar liquid with water.
  • said carrier liquid (A) is selected from alcohols having 1 to 5 carbon atoms, preferably ethanol.
  • a composition according to the present invention comprises the constituents (A) and (B) as defined above, and further comprises (C) one or more binding agents. Said binding agents are suspended or dissolved in said carrier liquid (A). Typically said binding agents are polymers. Said polymers are dissolved in the carrier liquid (A) or suspended in the carrier liquid (A).
  • the carrier liquid (A) as defined above and those poly- mers which are dissolved therein are monophase (i.e. form a single phase). Polymers which substantially do not dissolve in said carrier liquid (A) are present in the ink in the form of a latex (i.e. a colloidal dispersion) or of suspended discrete solid particles e.g. fibers or polymer beads.
  • a transparent electroconductive film obtained from an ink according to the present in- vention which comprises one or more binding agents (C)
  • said binding agents (C) form an optically transparent contiguous solid phase (herein referred to as a matrix).
  • Said matrix binds and accommodates the metal nanoobjects (B) within the transparent electroconductive film, fills the voids between said metal nanoobjects (B), provides mechanical integrity and stability to the transparent electroconductive film and binds the transparent electrocon- ductive film to the surface of the substrate.
  • the metal nanoobjects (B) dispersed within said matrix form a conductive network enabling the flow of electrons between adjacent and overlapping metal nanoobjects within the layer.
  • Preferred binding agents are selected from the group consisting of cellulose ethers (e.g.
  • poly(meth)acrylates copolymers of acrylates and/or methacrylates, copolymers of styrene and (meth)acrylates, polystyrene, polyacrylamides, polyvinylalcohol, polyvinylpyrrolidone, polystyrenesulfonic acid, polyesters, polyure- thanes, polycarbonates, gelatins, acrylic acid ester-vinyl acetate copolymers, dextran, and blends thereof.
  • (meth)acrylic includes “methacrylic” and “acrylic”.
  • composition according to the present invention optionally comprises further constituents beside the above-defined constituents (A) and (B) and optionally (C), e.g. defoaming agents, rheological controlling agents, corrosion inhibitors and other auxiliary agents. Typical defoaming agents, rheological controlling agents and corrosion inhibitors are known in the art and are commercially available.
  • compositions according to the present invention are those wherein two or more of the above-defined preferred features are combined.
  • composition according to the present invention comprises
  • a carrier liquid selected from alcohols having 1 to 5 carbon atoms, preferably ethanol
  • the weight fraction of said metal nanoobjects (B) is in the range of from 0.001 to 5 wt.%, more preferably 0.002 to 1 wt.% based on the total weight of the composition and/or
  • the ratio of the weight of Sn(ll) in the Sn(ll) compounds relative to the weight of the metal nanoobjects is in the range of from 0.01 % to 3.9 %, more preferably in the range of from 2.0 % to 2.5 %.
  • a composition according to the invention as defined above is suitable for disposing said metal nanoobjects (B) having their surfaces at least partially coated with a layer comprising one or more Sn(ll) compounds as defined above on a surface of a substrate.
  • a second aspect of the invention is related to the use of a composition according to the first aspect of the invention as defined above for disposing said metal nanoobjects (B) on a surface of a substrate, wherein the surfaces of said metal nanoobjects (B) are at least partially coated with a layer comprising one or more Sn(ll) compounds as defined above.
  • a method for preparing a composition for obtaining electroconductive transparent films comprising metal na- noobjects disposed on the surface of a substrate, especially a composition according to the first aspect of the invention as defined above. Said method comprising the steps of
  • the surfaces of the metal nanoob- jects (B0) are not coated with a layer comprising any Sn(ll) compounds. Only when in step (1 ), the surfaces of the metal nanoob- jects (B0) are not coated with a layer comprising any Sn(ll) compounds. Only when in step
  • a layer comprising one or more Sn(ll) compounds is formed which at least partially coats the surfaces of said dispersed metal nanoobjects (B0) so that a composition according to the first aspect of the invention as defined above is formed which comprises metal nanoobjects (B) dispersed in the carrier liquid (A), wherein the surfaces of said dispersed metal nanoobjects (B) are at least partially coated with a layer comprising one or more Sn(ll) compounds as defined above.
  • the Sn(ll) compound which immediately after being added to the precursor composition is dissolved in the carrier liquid (A) precipitates and/or adsorbs on the surfaces of the metal nanoobjects (BO) dispersed in the carrier liquid
  • the weight fraction of said metal nanoobjects (BO) is prefera- bly in the range of from 0.001 wt.% to 10 wt.%, preferably 0.001 to 5 wt.%, most preferably 0.002 to 1 wt.%, based on the total weight of the precursor composition.
  • the weight fraction of the metal nanoobjects (B0) in the precursor composition is too high the metal nanoobjects (B0) are not well dispersed in the ink.
  • the method may become ineffec- tive.
  • said Sn(ll) compound(s) is/are preferably added in an amount of from 0.02 wt.% to 10 wt.% relative to the weight of the metal nanoobjects (B0) in the precursor composition. More specifically, in step (2) of the method defined above, said Sn(ll) compound(s) is/are preferably added in such amount, that the ratio of the total weight of Sn(ll) in the added Sn(ll) compound(s) relative to the weight of the metal nanoobjects (B0) in the precursor composition (not including the Sn(ll) compound) is in the range of from 0.01 % to 5 %, more preferably of from 0.01 % to 3.9 %, most preferably in the range of from 2.0 % to 2.5 %.
  • the weight of added Sn(ll) relative to the weight of the metal nanoobjects (B0) in the precursor composition is too low, coating of the surfaces of the metal nanoobjects (B0) by the Sn(ll) compound(s) may be not sufficient to achieve the desired protection against thermal and oxidative stress and reactive chemicals. If the weight of added Sn(ll) relative to the weight of the metal nanoobjects (BO) in the precursor composition is too high, the coating of the surfaces of the metal nanoobjects by the Sn(ll) compound may become too thick, so that the sheet resistance of a transparent conductive film obtained using such metal nanoobjects may be undesirably high.
  • step (2) said Sn(ll) compound is added to said precursor composition in the form of a solution of said Sn(ll) compound in a liquid identical with the carrier liquid (A) of the precursor composition, wherein the weight fraction of Sn(ll) in said solution is in the range of from 0.001 wt.% to 0.5 wt.%, preferably 0.01 wt.% to 0.2 wt.%, most preferably 0.01 wt.% to 0.1 wt.%, in each case based on the total weight of said solution.
  • the carrier liquid (A) of the precursor composition is ethanol
  • said Sn(ll) compound is added to said precursor composition in the form of a solution of said Sn(ll) compound in ethanol, wherein the weight fraction of Sn(ll) in said solution is in the range of from 0.001 wt.% to 0.5 wt.%, preferably 0.01 wt.% to 0.2 wt.%, most preferably 0.01 wt.% to 0.1 wt.%, in each case based on the total weight of said solution.
  • the Sn(ll) compound is water-soluble without hydrolysis to SnO, a solution of the Sn(ll) compound in water may be used.
  • the Sn(ll) compound as such is liquid at 25 °C and 101 .325 kPa (as it is the case e.g. for Sn(ll) 2-ethylhexanoate), it may be added to the precursor composition in pure form.
  • the criteria for selecting the Sn(ll) compound, and as regards preferred Sn(ll) compounds the same applies as disclosed above in the context of the first aspect of the present invention.
  • step (2) after adding the Sn(ll) compound, preferably the composition is subject to mechanical agitation to ensure evenly dispersion between the metal nanoobjects and the added Sn(ll)compound.
  • this is done by means of shaking, jolting or by using devices selected from the group consisting of static mixers and dynamic mixers.
  • Silver nanowires are typically commercially available in the form of a suspension wherein the surfaces of the silver nanowires are coated with a layer of an organic protecting agent in order to render the suspension stable, i.e. to avoid agglomeration of the silver nanowires.
  • Said organic protecting agent does not comprise any Sn(ll) compound.
  • said organic protecting agent is selected from the group consisting of polyvinylpyrrolidone, polyvinyl alcohols, anionic surfactants (e.g. sodium do- decyl sulfate), laurylamine, hydroxypropylcellulose and fatty acids.
  • any matter adsorbed on the surface of the metal nanoobjects (BO) is not included in the definition of the dimensions of the metal nanoobjects (BO) and in the weight fraction of the metal nanoobjects (BO) relative to the weight of the precursor composition.
  • step (1 ) comprises
  • (1 .2) preparing a precursor composition from said primary precursor composition by adding to said primary precursor composition acetone in an amount of 0.1 ml to 5 ml acetone per mg metal nanoobjects (B0), removing the supernatant liquid and redispersing the metal nanoobjects (B0) in a fresh carrier liquid (A) selected from non- aqueous polar liquids,
  • further carrier liquid (A) to adjust the weight fraction of said metal nanoobjects (B0) in the range of from 0.001 wt.% to 10 wt.%, preferably 0.001 to 5 wt.%, most preferably 0.002 to 1 wt.%, based on the total weight of the precursor composition.
  • the carrier liquid (A0) of the primary precursor solution is typically the liquid in which the synthesis of the metal nanoobjects has been carried out.
  • said carrier liquid (A0) is typically selected from the polyols, preferably from the group consisting of ethylene glycol, propylene glycol and glycerol.
  • Adding acetone in sub-step (1 .2) of the above-defined preferred method causes the metal nanoobjects to precipitate.
  • the preparatory treatment (sub-step (1 .2)) promotes an at least partial displacement of the organic protecting agent adsorbed at the surface of the metal nanowires by the Sn(ll) compound which is added in step (2).
  • sub-step (1.2) the carrier liquid (AO) of the primary precursor composition is removed and replaced by a fresh carrier liquid (A) selected from non-aqueous polar liquids. Removal of the supernatant from the primary precursor composition may be facilitated by subjecting the precursor composition to centrifugation at 3000 rpm to 4000 rpm for 2 to 10 minutes.
  • Commercially available dispersions of silver nanowires may comprise excess AgCI from the preparation of the silver nanowires. It was found that chloride anions have a detrimental effect on the stability of silver nanowires in a transparent conductive film. Such excess of AgCI is also precipitated by adding acetone in stub-step (1.2).
  • preparing a precursor composition from said primary precursor composition (step 1.2) preferably comprises the following sub-steps:
  • step (1.2.3) subjecting the composition obtained in step (1.2.3) to centrifugation at 3000 rpm to 4000 rpm for 2 to 10 minutes, removing the supernatant liquid and re-dispersing the metal nanoobjects (B0) in a fresh carrier liquid (A) selected from non-aqueous polar liquids,
  • any AgCI precipitated by adding acetone in stub-step (1.2.1 ) is redissolved by adding ammonium hydroxide in sub-step (1.2.3) so that it can be removed with the supernatant in sub-step (1.2.4).
  • ammonia is preferably added in the form of an aqueous solution of ammonium hydroxide comprising 2.5 wt.% to 5 wt.% of ammonia NH3, preferably about 4 wt.% of ammonia.
  • Preferred methods according to the third aspect of the present invention are those wherein two or more of the above-defined preferred features are combined.
  • An especially preferred method according to the invention comprises the steps of
  • Sn(ll) compounds selected from the group consisting of Sn(ll) 2-ethylhexanoate, SnF2, Sn(ll) acetylacetonate and Sn(ll) methanesulfonate in an amount so that the ratio of the total weight of Sn(ll) in the added Sn(ll) compounds relative to the weight of the metal nanoobjects (B0) in the precursor composition is in the range of from 0.01 % to 3.9 %, more preferably in the range of from 2.0 % to 2.5 %.
  • an article comprising a substrate having a surface and, arranged on said surface of said substrate, a plurality of
  • (B) metal nanoobjects wherein the surfaces of said metal nanoobjects are at least partially coated with a layer comprising one or more Sn(ll) compounds with the proviso that said layer does not comprise any of SnCh, SnBr2 and Sn .
  • said plurality of metal nanoobjects optionally in combination with other sub- stances like binding agents, form a transparent electroconductive film arranged on the surface of said substrate.
  • Said layer comprising one or more Sn(ll) compounds on the surface of the metal nanoobjects (B) has a thickness of less than 10 nm, preferably less than 5 nm, further preferably less than 3 nm, most preferably about 1 nm, as measured by high resolution transmission electron microscopy (HRTEM).
  • HRTEM high resolution transmission electron microscopy
  • said Sn(ll) compound(s) is/are preferably present in such amount that the ratio of the total weight of Sn(ll) in the Sn(ll) compound(s) relative to the weight of the metal nanoobjects (B) (not including the Sn(ll) compound(s)) is in the range of from 0.01 % to 5 %, more preferably of from 0.01 % to 3.9 %, more preferably in the range of from 2.0 % to 2.5 %.
  • the weight of Sn(ll) relative to the weight of the metal nanoobjects (B) is too low, coating of the surfaces of the metal nanoobjects (B) by the Sn(ll) compound(s) may be not sufficient to achieve the desired protection against thermal and oxidative stress and against reactive chemicals. If the weight of Sn(ll) relative to the weight of the metal nanoobjects (B) is too high, the coating of the surfaces of the metal nanoobjects (B) by the Sn(ll) compound(s) may become too thick, so that the sheet resistance of a transparent conductive film containing such metal nanoobjects may be undesirably high.
  • the Sn(ll) compounds are preferably selected from the group consisting of Sn(ll) 2-ethylhexanoate, SnF2, Sn(ll) acetylacetonate, Sn(ll) methanesulfonate and SnO.
  • SnO may be obtained from an Sn(ll) compound, e.g. Sn(ll) 2-ethylhexanoate, by calcination when metal nanoobjects the surfaces of which are at least partially coated with a layer comprising Sn(ll) 2-ethylhexanoate are subject to an annealing treatment (for details see below), or by hydrolysis of an Sn(ll) compound, e.g. Sn(ll) 2 ethylhexanoate, SnF2, Sn(ll) acetylacetonate, Sn(ll) methanesulfonate.
  • Said substrate preferably comprises a material selected from the group consisting of plas- tics, glass, metals, silicon, and sapphire.
  • Said substrate is preferably in a form selected from the group consisting of foils, films, webs, panes and plates.
  • said substrate has a thickness in the range of from 10 pm to 200 pm, preferably from 50 pm to 100 pm.
  • said substrate comprises an optically transparent material selected from the group of glasses and organic polymers, which is electronically insulating.
  • Preferred types of glass are e.g. float glass, low iron float glass, heat strengthened glass and chemically strengthened glass.
  • the glass has a low-emissivity (low-e) coating, sun-protection coating or any other coating on the surface facing away from the above- described transparent electroconductive film.
  • Preferred organic polymers are selected from the group consisting of polymethylmethacrylate (PMMA, commercially available e.g.
  • PET polyethylene
  • LDPE low density polyethylene
  • LLDPE linear low density polyethylene
  • PP polypropylene
  • LDPP low density polypropylene
  • PET polyethylene therephthalate
  • PEN glycol modified polyethylene therephthalate
  • PL polyethylene naphthalate
  • PS polystyrene
  • PVC polyvinyl chloride
  • PI polypropylene oxide
  • PET and PEN are particularly preferred.
  • said substrate has a light transmittance of 80 % or more, more preferably 90 % or more, further preferably 95 % or more, in each case measured according to ASTM D1003 (Procedure A) as published in November 2013.
  • said article according to the invention has a sheet resistance in the range of from 10 ohms/sq. to 150 ohms/sq. as measured at a temperature of 25 °C and a pressure of 101.3 kPa by means of a four point probe placed on said plurality of metal nanoobjects (B) disposed on the surface of the substrate.
  • the sheet resistance (sometimes also referred to as“square resistance”) is a measure of the resistance of a thin body (sheet) namely uniform in thickness.
  • a transparent electro- conductive film as described herein may be considered as such a sheet-like thin body.
  • sheet resistance implies that the current flow is along the plane of the sheet, not perpendicular to it.
  • the resistance R is
  • R Sh is the sheet resistance. Accordingly, the sheet resistance R Sh is the sheet resistance.
  • the bulk resistance R is multiplied with a dimensionless quantity (W/L) to obtain the sheet resistance R Sh , thus the unit of sheet resistance is Ohms.
  • the sheet resistance is measured by means of a four point-probe which is positioned on said transparent electroconductive film comprising said plurality of metal nanoobjects (B) disposed on the surface of a substrate. Further preferably, said article according to the invention has
  • a haze of 3 % or less as measured according to ASTM D1003 (procedure A).
  • the measurement of haze and light transmittance by means of a hazemeter is defined in ASTM-D1003 as published in November 2013 as“Procedure A -Hazemeter”.
  • the values of haze and light transmittance given in the context of the present invention refer to this procedure.
  • the parameter“light transmittance” refers to the percentage of incident light which is trans- mitted through a medium (in the case of an article according to the invention through the substrate and the transparent electroconductive film disposed on the substrate).
  • the light transmittance is referred to as luminous transmittance which is the ratio of the luminous flux transmitted by a body to the flux incident upon it.
  • the light transmittance (corresponding to the luminous transmittance as defined in ASTM D1003 as published in November 2013) of an article according to the invention is 85 % or more, more preferably 90 % or more, further preferably 95 % or more, in each case measured according to ASTM D1003 (Procedure A) as published in November 2013 (corresponding to the luminous transmittance as defined in ASTM D1003 as published in No- vember 2013).
  • the parameter haze is an index of the light diffusion. It refers to the percentage of the quantity of light which is separated from the incident light and scattered during transmittance. Unlike light transmittance, which is largely a property of the medium, haze is often a production concern and is typically caused by surface roughness, and by embedded particles or compositional heterogeneities in the medium. According to ASTM D1003 as published in November 2013, haze is the scattering of light by a specimen responsible for the reduction in contrast of objects viewed through said specimen, i.e. the percent of transmitted light that is scattered so that its direction deviates more than a specified angle (2.5 °) from the direction of the incident beam.
  • the haze of the article according to the invention is 1.8 % or less, more preferably 1.5 % or less, further preferably 1 % or less, in each case measured according to ASTM D1003 (Procedure A) as published in November 2013.
  • said article according to the invention exhibits one or more of the following features:
  • the coverage of the surface of said substrate by said plurality of metal nanoobjects (B) is in the range of from 10 % to 65 %, preferably in the range of from 15 % to 35 %.
  • images of the surface having said plurality of metal nanoobjects disposed thereon are taken by optical microscopy or scanning electron microscopy, and the images are analyzed by means of an image analyzing software capable of differentiating within said images said metal nanoobjects (B) from the bare surface of the substrate and calculating the fraction of the surface covered by the metal nanoobjects (B).
  • said metal nanoobjects (B) are present on said surface of said substrate in a concentration of 1 mg/m 2 to 1000 mg/m 2 , preferably 5 mg/m 2 to 200 mg/m 2 , most preferably 20 mg/m 2 to 50 mg/m 2 .
  • said plurality of metal nanowires (B) is incorporated in an optically transparent matrix formed of one or more bind- ing agents (C) as defined above.
  • said preferred article comprises a substrate having a surface and, arranged on said surface of said substrate, a plurality of metal nanoobjects (B) as defined above, and said article further comprises one or more binding agents (C) as defined above on said surface of said substrate.
  • the metal nanoobjects (B) are dispersed in said matrix formed of said binding agents. Said matrix binds and accommodates the metal nanoobjects (B) in the transparent electroconductive film, fills voids between said metal nanoobjects, provides mechanical integrity and stability to the transparent electroconductive film and binds the transparent electroconductive film to the surface of the substrate.
  • Preferred articles according to the fourth aspect of the present invention are those wherein two or more of the above-defined preferred features are combined.
  • An especially preferred article according to the invention comprises
  • the substrate comprises one or more materials selected from the group consisting of glasses and organic polymers and has a light transmittance of 80 % or more as measured according to ASTM D1003 (procedure
  • Such preferred articles typically exhibit a sheet resistance and optical parameters (light transmittance and haze) falling in the above-defined ranges.
  • the present invention relates to the use of an article according to the present invention in a device selected from the group consisting of opto-electronic devices, solar cells, touch screens, wearable electronics, heaters, displays, piezo-electric generators and electrochromic windows.
  • a device selected from the group consisting of opto-electronic devices, solar cells, touch screens, wearable electronics, heaters, displays, piezo-electric generators and electrochromic windows.
  • the present invention relates to a method for preparing an article according to the fourth aspect of the invention. Said method comprises the steps of forming a wet film by applying a composition according to the first aspect of the invention to a surface of a substrate or to a surface of a temporary support,
  • the solid constituents of said composition according to the first aspect of the invention comprise at least the metal nanoobjects (B) wherein the surfaces of said metal nanoobjects (B) are at least partially coated with a layer comprising one or more Sn(ll) compounds.
  • a composition according to the first aspect of the invention (ink) either to a surface of a substrate or to a surface of a temporary support a wet film is formed on said surface. Then, the carrier liquid (A) of said composition is removed from the wet film formed on the surface of the substrate resp. on the surface of the temporary support.
  • a temporary support is a support that provides favorable conditions for removal of the carrier liquid (A), but is not suitable to function as a substrate in an article as defined above in the context of the fourth aspect of the invention.
  • the ink is applied to a temporary support, after removal of the carrier liquid (A) the solid constituents of the ink are transferred from the surface of said temporary support to a surface of a substrate.
  • Methods including the transfer of the solid constituents of the ink from a temporary support to a (permanent) substrate are also referred to as transfer coating methods.
  • the ink is applied to a substrate, after removal of the carrier liquid (A) the solid constituents of the ink are left on said surface.
  • a temporary support in the form of a filtration membrane is used, and removal of the carrier liquid (A) is achieved by means of filtration. Accordingly, said preferred specific method comprises the steps of
  • filtration is achieved by reducing the pressure beneath the filtration membrane, preferably by applying vacuum beneath the filtration membrane (vacuum filtration).
  • vacuum filtration Such filtration techniques are well-known in the art.
  • the filtration membrane is a hydrophobic polymer membrane, wherein said polymer is preferably selected from fluorinated polymers, most preferably polytetrafluoroeth- ylene PTFE, and has a pore size of from 100 to 80 nm. Suitable membranes are commercially available. The pore size is larger than the diameter of the metal nanowires but smaller than the length of the metal nanowires. The metal nanowires do not pass the pores, because due to the force of the applied vacuum from beneath the filtration membrane, the metal nanowires align on the filtration membrane with their length (which is larger than the pore size) perpendicular to the pores.
  • a wet film is formed on a surface of a substrate as defined above in the context of the fourth aspect of the invention, and removal of the carrier liquid (A) from said wet film is achieved by means of evaporation, so that solid constituents which are dissolved in the carrier liquid (A) remain on the surface of the substrate when the carrier liquid (A) is removed from the wet film.
  • said preferred specific method comprises the steps of
  • the composition according to the present invention is applied to the surface of said substrate by coating or printing, preferably by a coating technique selected from the group consisting of roll-to-roll-, slot-die-, spray-, ultrasonic spray-, dip- and blade coating, or by a printing technique selected from the group consisting of ink-jet-, pad-, offset-, gravure-, screen-, intaglio- and sheet-to-sheet- printing.
  • the wet film formed by applying the composition according to the present invention to said surface of said substrate has a thickness in a range of from 1 pm to 100 pm, preferably of from 2 pm to 50 pm. Said thickness is also referred to as“wet thick-ness”.
  • the carrier liquid (A) is removed from said wet film on said surface of said substrate by exposing said wet film to a temperature in the range of from 20 °C to 120 °C, preferably of form 40 °C to 120 °C, most preferably of from 80 °C to 120 °C, so that the carrier liquid (A) evaporates, thereby forming on said surface of said substrate a transparent electroconduc- tive film.
  • a method according to the sixth aspect of the invention further comprises the step of annealing said metal nanoobjects (B) on the surface of the substrate at a temperature in the range of from 140 °C to 200 °C, preferably of from 140 °C to 160 °C under air atmosphere for a duration of 10 minutes to 60 min, preferably to 20 minutes to 40 minutes.
  • annealing may serve to improve the electronic conductivity of a transparent electroconductive film comprising a plurality of metal nanoobjects (B) wherein the surfaces of said metal nanoobjects are at least partially coated with a layer comprising one or more Sn(ll) compounds as defined above, but it is not prerequisite for the desired effect of protecting the metal nanoobjects (B) against oxidation.
  • a corresponding annealing treatment typically results in a decrease of the electronic conductivity as a result of thermal and oxidative stress (see comparison example below).
  • Sn(ll) compounds like Sn(ll) 2-ethyhexanoate are calcined to SnO which is partly, but not completely oxidized to Sn0 2 .
  • the surfaces of the metal nanoobjects (B) are at least partially coated with a layer comprising a mixed oxide of SnO and Sn0 2 .
  • the metal nanoobjects (B) after annealing are still at least partially coated with a layer comprising a Sn(ll) compound, namely SnO.
  • a Sn(ll) compound namely SnO.
  • the sim- ultaneous presence of Sn(ll) and Sn(IV) in transparent electroconductive films, which have been subject to the annealing treatment as defined above is detectable by means of X-ray photon spectroscopy (XPS), see examples below.
  • XPS X-ray photon spectroscopy
  • a seventh aspect of the present invention relates to the use of a Sn(ll) compound for preparing a composition according to the first aspect of the present invention.
  • Sn(ll) compound for at least partially coating the surfaces of metal nanoobjects dispersed in a carrier liquid (A) selected from non-aqueous polar liquids is effective in increasing the stability of transparent electroconductive films comprising said metal nanoobjects against oxidation and thermal stress and against reactive chemicals, provided that the Sn(ll) compounds meets the above-defined criteria, i.e. is soluble in an identical carrier liquid (A) which has no metal nanoobjects dispersed therein and is not selected from the group consisting of SnC , SnBr 2 and Snh.
  • Fig. 5a sheet resistances and light transmittances of a series of articles according to the invention before and after annealing at 100 °C
  • Fig. 5b the sheet resistance of an article according to the invention and of a comparison article as function of time during dynamic heating
  • Fig. 7 sheet resistances of articles according to the invention and of a comparison article before and after oxidative treatment
  • Fig. 8 sheet resistances of articles according to the invention and of a comparison article before and after exposure to H2S 1. Preparation of inks according to the invention and of comparison inks
  • Inks according to the first aspect of the invention comprising a plurality of silver nanowires (B) dispersed in ethanol (A), wherein the surfaces of said dispersed silver nanowires (B) are at least partially coated with a layer comprising a Sn(ll) compound selected from the group consisting of Sn(ll) 2-ethylhexanoate, SnF2, Sn(ll) acetylacetonate and Sn(ll) methanesulfonate were prepared by a method according to the third aspect of the invention as described above. 1.1 Preparation of a precursor composition for the method according to the invention
  • a primary precursor composition comprising 0.44 wt.% silver nanowires (BO) in ethylene glycol (solvent for synthesizing silver nanowires) was provided (step 1.1 ).
  • said primary precursor composition the surfaces of said dispersed metal nanoobjects (B) were coated with a layer of polyvinylpyrrolidone PVP (organic protecting agent).
  • the silver nanowires had an average length of 100 pm and an average diameter of 50 nm.
  • step 1.2.3 10 to 15 ml of acetone were added to 2.5 ml of said primary precursor composition (step 1.2.1 ) so that the silver nanowires were precipitated at the bottom of the vessel.
  • the su- pernatant liquid was removed and the silver nanowires were redispersed in 10 ml ethanol (step 1.2.2).
  • 0.5 ml aqueous solution of ammonium hydroxide (comprising 4 wt.% of ammonia) is added to the silver nanowires (B0) redispersed in ethanol obtained in step (1.2.2) to dissolve any AgCI which was co-precipitated in step (1.2.1 ), and the composition was allowed to settle for 2 minutes (step 1.2.3).
  • inks according to the first aspect of the invention were obtained, said inks comprising
  • Transparent conducting films each comprising a plurality of silver nanowires (B), wherein the surfaces of said silver nanowires (B) are at least partially coated with a layer comprising a Sn(ll) compound selected from the group consisting of Sn(ll) 2-ethylhexanoate, SnF2, Sn(ll) acetylacetonate, Sn(ll) methanesulfonate and SnO on pre-cleaned surfaces of glass substrates were prepared by a method according to the sixth aspect of the invention as described above.
  • the ethanol (carrier liquid (A) of the ink) was removed from the wet film formed on the surface of said filtration membrane by means of vacuum filtration so that on the surface of said filtration membrane a filtration residue is formed which comprises said silver nanowires (B) wherein said silver nanowires (B) form an interconnected network.
  • the filtration residue was transferred onto the surface of a pre-cleaned glass substrate by pressing said glass substrate onto the filtration residue disposed on the filtration membrane while vacuum is applied from beneath the filtration membrane, thereby forcing an intimate contact of the filtration residue with the glass substrate. Finally, the vacuum was removed and the filtration membrane was lifted away.
  • Comparison articles were obtained in the same manner using the comparison ink described in section 1.3 above.
  • Articles according to the invention and comparison articles were subject to annealing at different temperatures (100 °C, 200 °C or 300 °C, as indicated below) under ambient air in a conventional oven for 30 minutes.
  • the transparent electroconductive film was arranged on a surface of a glass substrate, as described above in section 2.
  • the appearance of the silver nanowires in the transparent electroconductive films was studied by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) before annealing and after annealing (after the annealed article was cooled down).
  • the crystal structure of the silver in the transparent electroconductive films was studied by means of X-ray dif- fraction (XRD) before annealing and after annealing (after the annealed article was cooled down).
  • the composition of the transparent electroconductive film was studied by means of Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) before annealing and after annealing (after the annealed article was cooled down).
  • the sheet resistance of the transparent electroconductive films was determined before an- nealing and after annealing (after the annealed article was cooled down) at a temperature of 25 °C and a pressure of 101.3 kPa by means of a four point probe placed on said plurality of metal nanoobjects (B) disposed on the surface of the substrate.
  • the light transmittance of the articles was determined before annealing and after annealing (after the annealed article was cooled down) according to ASTM D1003, procedure A using Shimadzu UV3600 UV-VIS-NIR spectrometer.
  • FIG. 1a SEM images (Fig. 1a) of a transparent electroconductive film comprising a plurality of silver nanowires (B), wherein the surfaces of said silver nanowires (B) are at least partially coated with a layer comprising Sn(ll) 2-ethylhexanoate show that the silver nanowires are uniformly dispersed and are present in high purity without other particles being present.
  • enlarged SEM images (Fig. 1 b) the junctions between individual silver nanowires can be observed, demonstrating sufficient contact between individual silver nanowires. No breaking of silver nanowires is observed.
  • TEM images obtained after annealing at 200 °C for 30 minutes and subsequent cooling show that the silver nanowires apparently have a core-shell structure
  • HRTEM images reveal a thin shell having a thickness of less than 2 nm that is evenly distributed over the surface of silver nanowires, confirming that the silver nanowires are uniformly coated.
  • Raman spectra (fig. 2a) of articles according to the invention confirm the presence of SnOx (mixed oxide of SnO and SnC ) on the surface of the silver nanowires after annealing.
  • the Raman spectra of the articles according to the invention have two distinct Raman vibration peaks at 1374 and 1602 cnr 1 due to Sn-0 bond vibrations. The intensity of these peaks increases when the amount of Sn(ll) 2-ethylhexanoate added during step (2) of the method for producing the ink increases.
  • XPS analysis (fig. 2b) was performed to identify the element composition at the surface of the silver nanowires in the article according to the invention obtained using the ink with 0.5 mI of Sn(ll) 2-ethylhexanoate added during step (2) of the method for producing the ink, see section 1.2 above. Besides the peaks of the element Ag, the peaks of the elements Sn, C and O can be clearly observed, see fig. 2b.
  • the high resolution XPS pattern of Sn (not shown) exhibits large Sn 2+ peaks, but only a weak signal for Sn 4+ . Apparently, despite the annealing treatment under air atmosphere, most of the detectable Sn is Sn(ll) instead of being oxidized to Sn (IV).
  • a series of articles according to the invention having electroconductive transparent films was obtained by applying inks having different weight fraction of silver nanowires (B) (0.002 wt.% to 0.5 wt.%) wherein the surfaces of said silver nanowires (B) are at least partially coated with a layer comprising Sn(ll) 2-ethylhexanoate.
  • the same volume of ink (20 ml) was applied, thereby obtaining transparent electroconductive films having different amounts of silver nanowires per unit of surface area of the substrate.
  • the sheet resistance and the light transmittance are the higher the lower the amount of silver nanowires per unit of surface area of the substrate. Annealing under air atmosphere at 100 °C appears to have little influence on the light transmittance but results in a moderate increase of the sheet resistance, which is more pronounced when the amount of silver nanowires per unit of surface area of the substrate is low. Nevertheless, in each case the sheet resistance and the light transmittance had acceptable values falling in the above-defined preferred ranges.
  • the sheet resistance of the comparison article (labelled “AgNWs film”, left part of fig. 5b) continuously increases up to the temperature range of from 180 °C to 200 °C, where a steep increase starts.
  • the initial sheet resistance of the article according to the invention (right part of fig. 5b) at room temperature is higher than that of the comparison article, but steeply decreases when the temperature increases.
  • the composition of the transparent electroconductive films was studied by means of Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) before the oxidative treatment and after the oxidative treatment (after the article was cooled down).
  • the sheet resistance of the transparent electroconductive films was determined before the oxidative treatment and after the oxidative treatment (after the article was cooled down) at a temperature of 25 °C and a pressure of 101.3 kPa by means of a four point probe placed on said plurality of metal nanoobjects (B) disposed on the surface of the substrate.
  • An article (3) having a transparent electroconductive film comprising a plurality of silver nanowires (B), wherein the surfaces of said silver nanowires (B) are at least partially coated with a layer comprising SnF2, and a comparison article were subject to the oxidation treatment described above.
  • the XPS pattern of the comparison article (labelled“AgNWs) recorded before the oxidative treatment exhibits peaks attributable to silver and those attributable to carbon resp. oxygen originating from traces of the surface protection agent PVP (fig. 6a), while the XPS pattern of article (3) according to the invention exhibits additional peaks attributable to Sn and F (fig 6b).
  • the Ag peaks in the XPS pattern shift significantly, indicating oxidation of the silver of the silver nanowires (fig 6c).
  • the Ag peaks in the XPS pattern do not change, indicating that the silver nanowires are not oxidized (fig. 6d).
  • Articles (4), (5) and (6) obtained using inks produced by adding different amounts (0.3 pi, 0.5 mI and1 mI, resp.) of Sn(ll) 2-ethylhexanoate in step (2) of the method for producing the ink (see section 1.2 above), and a comparison article were subject to the oxidation treatment described above.
  • the thickness of the layer comprising Sn(ll) 2-ethylhexanoate on the surface of the silver nanowires increases with increasing amount of Sn(ll) 2-ethylhexanoate added during step (2) of the method for producing the ink (see section 1.2 above).
  • the sheet resistance (see figure 7) of the comparison article is lower than that of the articles according to the invention, because in the comparison article the silver nanowires are not coated with a layer comprising a Sn(ll) compound.
  • the comparison article a significant increase of the sheet resistance after the ox- idative treatment is observed.
  • articles (4) and (5) only a slight increase of 10 ohms/sq. in sheet resistance was observed, showing favorable stability against oxidation even under severe conditions.
  • Article (6) exhibited a high sheet resistance already before annealing, due to the high weight of added Sn(ll) 2-ethylhexanoate added in step (2) relative to the weight of the silver nanowires (B0) in the precursor composition (see section 1.2 above). Apparently the coating of the surfaces of the silver nanowires by Sn(ll) 2-ethylhexanoate was rather thick in article (6), so that the sheet resistance of the transparent conductive film obtained using said ink was rather high. In addition, the significant increase of the sheet resistance of article (6) after the oxidative treatment indicates that in article (6) the presence of Sn(ll) 2-ethylhexanoate did not provide sufficient protection against the oxidative stress applied in this test.
  • article (5) obtained using the ink produced by adding 0.5 pi Sn(ll) 2-ethylhexanoate has the lowest sheet resistance before and after the oxidative treatment
  • articles (4) and (6) obtained using the ink produced by adding a lower resp. higher amount of Sn(ll) 2-ethylhex- anoate exhibit a higher sheet resistance.
  • the ratio of the weight of Sn(ll) in the Sn(ll) compound relative to the weight of the silver nanowires (B) requires careful optimisation for obtaining an optimal protection against oxidation.
  • Articles (7), (8) and (9) according to the invention and a comparison article were exposed to an atmosphere consisting of H2S and N2 (50 vol.% each) for 10 hours at room temperature.
  • the transparent electroconductive film was arranged on a surface of a glass substrate, as described above in section 2.
  • the sheet resistance of the transparent electroconductive films was determined at a temperature of 25 °C and a pressure of 101.3 kPa by means of a four point probe placed on said plurality of metal nanoobjects (B) disposed on the surface of the substrate before the exposure to H2S, after 5 hours of exposure to H2S and after 10 hours of exposure to H2S.
  • Articles (7), (8) and (9) obtained using inks produced by adding different amounts (0.3 pi, 0.5 mI and1 mI, resp.) of Sn(ll) 2-ethylhexanoate added in step (2) of the method for pro- ducing the ink (see section 1.2 above) and a comparison article were exposed to H2S as described above.
  • the thickness of the layer comprising Sn(ll) 2- ethylhexanoate on the surface of the silver nanowires (B) increases with increasing amount of Sn(ll) 2-ethylhexanoate added during step (2) of the method for producing the ink (see section 1.2 above).
  • the sheet resistance (see figure 8) of the comparison article is lower than that of the articles according to the invention, because in the comparison article the silver nanowires are not coated with a layer comprising a Sn(ll) compound.
  • the sheet resistance does not exceed 150 Ohms/sq.
  • Article (9) exhibited a high sheet resistance already before exposure to H2S, due to the high weight of added Sn(ll) 2-ethylhexanoate relative to the weight of the silver nanowires (B0) in the precursor composition in step (2) of the method for producing the ink (see section 1.2 above). Apparently the coating of the surfaces of the silver nanowires by Sn(ll) 2-ethylhexanoate was rather thick in article (9), so that the sheet resistance of the transparent conductive film obtained using said ink was rather high. Article (9) exhibits a significant increase of the sheet resistance after the exposure to H2S, although less than for the comparison article.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Non-Insulated Conductors (AREA)
  • Manufacturing Of Electric Cables (AREA)
  • Conductive Materials (AREA)

Abstract

L'invention concerne une composition (encre) comportant des nano-objets métalliques pour la préparation d'un film électroconducteur transparent. La composition comprend un liquide porteur choisi parmi des liquides polaires non aqueux et des nanoparticules métalliques dispersées dans ledit liquide porteur, la surface des nanoparticules étant au moins partiellement revêtue d'une couche comprenant un ou plusieurs composés de Sn (ll) qui sont solubles dans le liquide porteur.
PCT/EP2019/067867 2018-08-20 2019-07-03 Films électroconducteurs transparents et encre pour leur production WO2020038641A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP18189806 2018-08-20
EP18189806.5 2018-08-20

Publications (1)

Publication Number Publication Date
WO2020038641A1 true WO2020038641A1 (fr) 2020-02-27

Family

ID=63311929

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2019/067867 WO2020038641A1 (fr) 2018-08-20 2019-07-03 Films électroconducteurs transparents et encre pour leur production

Country Status (2)

Country Link
TW (1) TW202012559A (fr)
WO (1) WO2020038641A1 (fr)

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7922787B2 (en) 2008-02-02 2011-04-12 Seashell Technology, Llc Methods for the production of silver nanowires
US8049333B2 (en) 2005-08-12 2011-11-01 Cambrios Technologies Corporation Transparent conductors comprising metal nanowires
US20140020737A1 (en) 2012-07-18 2014-01-23 Research & Business Foundation Sungkyunkwan University Silver nanowire conductive film and method of fabricating the same
WO2014133890A2 (fr) * 2013-02-26 2014-09-04 C3Nano Inc. Réseaux nanostructurés de métal fondu, solutions de fusion avec agents de réduction et procédés de formation de réseaux métalliques
US20140255707A1 (en) 2013-03-06 2014-09-11 Carestream Health, Inc. Stabilization agents for silver nanowire based transparent conductive films
WO2016023904A1 (fr) 2014-08-15 2016-02-18 Basf Se Composition comprenant des nanofils d'argent et des fibres de cellulose cristalline pour la préparation de couches transparentes électroconductrices
WO2016023889A1 (fr) 2014-08-15 2016-02-18 Basf Se Composition comprenant des nanofils d'argent et des billes de polymère dispersées pour la préparation de couches transparentes électroconductrices
WO2016023887A1 (fr) 2014-08-15 2016-02-18 Basf Se Composition comprenant des nanofils d'argent et des copolymères styrène/(méth)acryliques permettant la préparation de couches transparentes électroconductrices
US20160225483A1 (en) 2015-01-30 2016-08-04 Xerox Corporation Transparent conductive film comprising silver nanowires
US9449734B2 (en) 2010-08-27 2016-09-20 Lg Chem, Ltd. Conductive metal ink composition, and method for preparing a conductive pattern
EP3101663A1 (fr) 2014-01-31 2016-12-07 Zeon Corporation Film conducteur transparent, photoélectrode pour cellules solaires à colorant, écran tactile et cellule solaire à colorant
US20180134908A1 (en) 2015-04-16 2018-05-17 Basf Se Process for producing a patterned transparent conductive film and a transparent conductive film

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8049333B2 (en) 2005-08-12 2011-11-01 Cambrios Technologies Corporation Transparent conductors comprising metal nanowires
US7922787B2 (en) 2008-02-02 2011-04-12 Seashell Technology, Llc Methods for the production of silver nanowires
US9449734B2 (en) 2010-08-27 2016-09-20 Lg Chem, Ltd. Conductive metal ink composition, and method for preparing a conductive pattern
US20140020737A1 (en) 2012-07-18 2014-01-23 Research & Business Foundation Sungkyunkwan University Silver nanowire conductive film and method of fabricating the same
WO2014133890A2 (fr) * 2013-02-26 2014-09-04 C3Nano Inc. Réseaux nanostructurés de métal fondu, solutions de fusion avec agents de réduction et procédés de formation de réseaux métalliques
US10020807B2 (en) 2013-02-26 2018-07-10 C3Nano Inc. Fused metal nanostructured networks, fusing solutions with reducing agents and methods for forming metal networks
US20140255707A1 (en) 2013-03-06 2014-09-11 Carestream Health, Inc. Stabilization agents for silver nanowire based transparent conductive films
EP3101663A1 (fr) 2014-01-31 2016-12-07 Zeon Corporation Film conducteur transparent, photoélectrode pour cellules solaires à colorant, écran tactile et cellule solaire à colorant
WO2016023904A1 (fr) 2014-08-15 2016-02-18 Basf Se Composition comprenant des nanofils d'argent et des fibres de cellulose cristalline pour la préparation de couches transparentes électroconductrices
WO2016023889A1 (fr) 2014-08-15 2016-02-18 Basf Se Composition comprenant des nanofils d'argent et des billes de polymère dispersées pour la préparation de couches transparentes électroconductrices
WO2016023887A1 (fr) 2014-08-15 2016-02-18 Basf Se Composition comprenant des nanofils d'argent et des copolymères styrène/(méth)acryliques permettant la préparation de couches transparentes électroconductrices
US20160225483A1 (en) 2015-01-30 2016-08-04 Xerox Corporation Transparent conductive film comprising silver nanowires
US20180134908A1 (en) 2015-04-16 2018-05-17 Basf Se Process for producing a patterned transparent conductive film and a transparent conductive film

Also Published As

Publication number Publication date
TW202012559A (zh) 2020-04-01

Similar Documents

Publication Publication Date Title
JP6676712B2 (ja) 透明導体の製造方法
EP2430639A1 (fr) Films conducteurs fiables et durables comprenant des nanostructures métalliques
US20110024159A1 (en) Reliable and durable conductive films comprising metal nanostructures
US9318230B2 (en) Nanostructure dispersions and transparent conductors
KR101386362B1 (ko) 은 나노와이어 네트워크―그래핀 적층형 투명전극 소재, 그 제조 방법 및 이를 포함하는 투명전극
TW201544610A (zh) 銀奈米線的製造方法與銀奈米線以及使用該銀奈米線的印墨
JP5405935B2 (ja) 透明導電性シート
CA2957843A1 (fr) Composition comprenant des nanofils d'argent et des billes de polymere dispersees pour la preparation de couches transparentes electroconductrices
KR20170045669A (ko) 도전체, 그 제조 방법, 및 이를 포함하는 소자
KR20170053462A (ko) 금속 산화물 나노시트들의 집단과 그 제조 방법, 및 이를 포함하는 도전체 및 전자 소자
CN107025951B (zh) 电导体、其制造方法、和包括其的电子器件
WO2020038641A1 (fr) Films électroconducteurs transparents et encre pour leur production
Izaki et al. Transparent conducting and highly stable indium-incorporated zinc oxide film prepared by chemical reactions
WO2021075495A1 (fr) Film conducteur, dispersion, procédés pour leur fabrication, et dispositif comprenant un film conducteur
Potočnik et al. Optical properties of copper helical nanostructures: the effect of thickness on the SPR peak position
TWI634081B (zh) 摻雜銀的氧化鋁鋅複合靶材及其製作方法
Najafi et al. The effect of Cu-doping on physical properties of nanostructured NiO thin films prepared by spray pyrolysis technique
Zhou et al. Mixed phase F-doped SnO 2 film and related properties deposited by ultrasonic spraying
KR102357733B1 (ko) 전도층 및 그 제조방법
WO2018019820A1 (fr) Couche électroconductrice transparente dotée d'un revêtement protecteur
Conti et al. Electrical properties of SnO2: Sb ultrathin films prepared by colloidal deposition process
KR20230050055A (ko) 투명 전도성 전극
Jutarosaga et al. Synthesis and Physical Properties of Semi-Transparent Conductive Ag-Nanowire Network

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 19739536

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 19739536

Country of ref document: EP

Kind code of ref document: A1