TW202012559A - Transparent electroconductive films and ink for production thereof - Google Patents

Abstract

Described is a composition (ink) comprising metal nanoobjects for preparing a transpar-ent electroconductive film.

Description

Transparent conductive film and its ink

The present invention relates to a composition suitable for preparing a conductive transparent film, a method for preparing the composition, uses of the composition, a product including a conductive transparent film, uses of the product, and a method for preparing the product.

Metal nano-objects, especially metal nano-wires, such as silver nano-wires, are commonly used to prepare transparent conductive films. The term "transparent conductive film" as used herein refers to (i) capable of allowing current to flow when an appropriate voltage is applied and (ii) measured in accordance with ASTM D1003 in the visible light region (400-700 nm) with 80% or For films with higher light transmittance, see for example US 8,049,333. Typically, the film is arranged on the surface of a substrate, where the substrate is typically an electrical insulator and has at least as high a light transmittance as the transparent conductive film. Such conductive transparent films are widely used in displays, touch panels, electroluminescent devices, organic light-emitting diodes, thin-film photovoltaic cells, as antistatic layers and electromagnetic wave shielding layers.

Typically, such conductive transparent films are prepared by means of wet processing techniques. A suspension (commonly referred to as ink) containing metallic nano-objects dispersed in a carrier liquid is applied to the surface of the substrate by means of wet processing techniques, thereby forming a wet film on the surface, and then removed from the wet film The carrier liquid forms a conductive transparent film containing metal nano-objects on the surface of the substrate. Due to the small size of the metallic nano-object, its effect on the optical properties of the film is small, thus allowing the formation of optically transparent and conductive films.

Unfortunately, metal nano-objects such as silver nanowires are very sensitive to chemical and thermal degradation because the specific surface area is significantly increased compared to the corresponding bulk metals. The oxidation, thermal breakage and accumulation of metallic nano-objects usually result in a significant decrease in the conductivity and optical properties of conductive transparent films containing such metallic nano-objects.

During the manufacture of devices (such as displays) containing transparent conductive films, metallic nano-objects may be exposed to temperatures of 350°C or higher. In addition, during its use, the transparent conductive film may be exposed to heat and oxidative stress from the environment. The high current density that may occur during the use of the transparent conductive film and electrostatic discharge may cause thermal destruction and aggregation and/or oxidation of metallic nano-objects due to the released heat.

Therefore, there is a need to improve the stability of metal nano-objects in transparent conductive films against thermal and oxidative stress and reactive chemicals such as H ₂ S.

To solve these problems, US 2014/0020737 A1 proposes a device including a substrate, a silver nanowire disposed on the substrate, and an oxidation protection layer coated on the silver nanowire, wherein the oxidation protection layer includes Oxide. The oxidation protection layer is applied by means of atomic layer deposition (ALD) method. Preferably, the oxide-based metal oxide or metalloid oxide includes at least one selected from the group consisting of Ti, V, Ni, Cu, Zn, Zr, Nb, Y, Al, Si, Sn, and In . A protective layer composed of titanium dioxide TiO ₂ is preferred.

Atomic layer deposition (ALD) is a vacuum technology that requires specific expensive technical equipment. Vacuum technology cannot be easily integrated into a continuous process (eg, roll-to-roll-process) for preparing transparent conductive conductive films. In fact, after the metal nano-object to be protected is placed on the substrate, an oxidation protection layer must be applied as an additional processing step by means of atomic layer deposition.

Related technologies US 9,449,734 B2, US 10 020 807 B2, EP 3 101 663 A1.

In order to reduce equipment costs and improve processing efficiency, it is desirable to provide oxidation protection for metal nano-objects by means of wet processing, which can be combined with metal nano-object preparation and ink preparation stages. In addition, it is desirable to provide inks containing metal nano-objects that are protected from oxidation so that no additional oxidation protection treatment steps are required after the metal nano-objects are placed on the substrate.

An object of the present invention is to provide a composition (ink) for preparing a transparent conductive film containing metal nano-objects, the transparent conductive films having enhanced stability against oxidation, thermal stress and reactive chemicals In order to avoid the decrease of conductivity and optical properties of such conductive transparent films.

According to a first aspect of the present invention, there is provided a composition comprising (A) a carrier liquid selected from a non-aqueous polar liquid (B) a metallic nano-object dispersed in the carrier liquid (A), wherein the dispersion The surface of the metallic nano-object (B) is at least partially coated with a layer containing one or more Sn(II) compounds wherein the Sn(II) compounds are selected from the same soluble in which the metallic nano-object is not dispersed The Sn(II) compound in the carrier liquid (A) is subject to the restriction that the layer does not contain any one of SnCl ₂ , SnBr ₂ and SnI ₂ .

Herein, the composition according to the present invention (as defined above) is also called ink.

Surprisingly, it was found that the ink according to the present invention can obtain conductive transparent films including metal nano-objects provided on the surface of the substrate, wherein the metal nano-objects have enhanced oxidation resistance, thermal stress resistance and resistance The stability of reactive chemicals to avoid excessive decrease in conductivity and excessive decrease in optical properties of conductive transparent films. In addition, by using the ink according to the present invention, the preparation of products containing transparent conductive films that have enhanced stability against oxidation, thermal stress, and reactive chemicals can be eased because they do not need to The protective coating is applied in a separate step, as in the disclosure of US 2014/0020737 A1.

Preferably, the metal nano objects (B) are selected from the group consisting of metal nano wires, metal nano particles, metal nano rods, metal nano fibers, metal nano flakes, metal nano plates and Metal nanobelts and their mixtures.

According to ISO/TS 27687:2008 (published in 2008), the term "nano object" refers to one, two, or three nano-level external dimensions, that is, one with dimensions in the range of about 1 nm to 100 nm, Two or three external dimensions.

According to ISO/TS 27687:2008, a nano object with one nano-level external dimension and two other external dimensions that are significantly larger is often called a nano-plate. The one nanometer external dimension corresponds to the thickness of the nanoplate. The difference between the two significantly larger sizes and the nanoscale size is more than three times. The two larger external dimensions are not necessarily nano-scale. Another commonly used term for nano objects with one nano-level external dimension and two other external dimensions that are significantly larger is "nano sheet".

According to ISO/TS 27687:2008, nano-objects with two similar nano-level external dimensions and a third external dimension that is significantly larger are commonly referred to as nano-fibers. The third significantly larger size differs from the nano-size by more than three times. The largest external dimensions are not necessarily nano-level. This maximum external dimension corresponds to the length of the nanofiber. Nanofibers typically have a nearly circular cross-section. The cross section extends perpendicular to the length. Therefore, the two nanoscale external dimensions are defined by the diameter of the circular cross-section. Conductive nanofibers are also called nanowires. Hollow nanofibers (regardless of their electrical conductivity) are also called nanotubes. Nano objects with two similar nano-level external dimensions and a third external dimension (length) with significantly greater rigidity (that is, non-flexibility) are commonly referred to as nanorods. Nano objects with two similar nano-level external dimensions, while the third external dimension (length) is significantly larger, and has a near-rectangular cross-section extending perpendicular to the length are commonly referred to as nanoribbons.

According to ISO/TS 27687:2008, nano-objects with all three nano-level external dimensions are generally called nano-particles, where the difference between the longest axis length and the shortest axis length of the nano-object does not exceed three times. All three orthogonal outer dimensions are approximately equal in length, that is, nanoparticles with an aspect ratio (longest: shortest direction) close to 1 are usually called nanospheres.

The term "metallic nano-object" means that the nano-object includes or consists of one or more materials selected from the group consisting of metals and metal alloys. Since metals can allow electrons to flow, a plurality of such metal nano-objects arranged on the surface of the substrate can form a conductive mesh structure composed of adjacent and overlapping nano-objects capable of carrying electric current, and the limitation is individual metal nano-objects There are enough interconnections (contacts) between the rice objects so that they can transmit electrons along the interconnected metal nano-objects within the mesh structure.

Preferably, the metal nano-objects include 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 these metals Or consist of it.

The best metal nano-material system metal nano flakes and metal nano wires are preferably selected from the group consisting of silver nano wires and copper nano wires.

Preferably, the metal nanowires of the metal nanomaterial system are preferably metal nanowires with a length of 10 μm to 100 μm and a diameter in the range of 10 to 200 nm. The length and diameter of the metal nanowire are determined by one of scanning electron microscope and transmission electron microscope, preferably transmission electron microscope. Preferably, the metal nanowires include 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 these metals Or consist of it. Silver nanowires and copper nanowires with a length of 10 μm to 100 μm and a diameter in the range of 10 to 200 nm are the best, in each case measured by one of scanning electron microscope and transmission electron microscope , Better transmission electron microscope.

Suitable metallic nano-objects as defined above and methods of obtaining them are known in the art (see for example US 7,922,787) and are commercially available. It should be noted that the advantageous effects of the present invention are not restricted by any specific technology of synthetic metal nano-objects.

Preferably, in the composition according to the invention (as defined above), the concentration of the metallic nano-objects (B) as defined above is in the range of 0.001% to 10% by weight based on the total weight of the composition , Preferably in the range of 0.001 to 5% by weight, most preferably in the range of 0.002 to 1% by weight. When the weight fraction of the metal nano-object (B) is too high, the metal nano-object cannot be well dispersed in the ink. When the weight fraction of the metal nano-object (B) is too low, the amount of metal nano-object deposited per unit surface area of the substrate may not be sufficient to form an interconnected conductive mesh structure, so this type of ink is not suitable for preparing a conductive film. In addition, when the weight fraction of metal nanoparticles (B) in the ink is low, the amount of carrier liquid (A) that must be removed in the process of forming the transparent conductive film is relatively large relative to the amount of metal nanoparticles deposited , And processing may become inefficient.

The Sn(II) compound as defined above and any substance adsorbed on the surface of the metal nano-object (B) are not included in the above-defined dimensions of the metal nano-object (B) and are not included in the metal nano-object (B) ) In the weight fraction relative to the weight of the composition according to the invention.

In the composition according to the invention, the surfaces of the dispersed metal objects are at least partially coated with a layer containing one or more Sn(II) compounds.

The term "Sn(II) compound" means a compound containing Sn having a +2 oxidation state. Therefore, a metal nano-object having a coating containing SnO ₂ (Sn(IV) oxide) and not having Sn in the +2 oxidation state is not a metal nano-object (B) as defined above. On the other hand, it is not excluded that the coating of metal nano-objects in the composition according to the invention contains Sn in the +4 oxidation state in addition to Sn in the +2 oxidation state.

The Sn(II) compounds are selected from Sn(II) compounds soluble in the same carrier liquid (A) in which no metallic nano-objects are dispersed. The Sn(II) compound is not selected from the group consisting of SnCl ₂ , SnBr ₂ and SnI ₂ .

When calculated based on the total weight of the carrier liquid (A) and the dissolved Sn(II) compound (where no metallic nano-particles are dispersed in the carrier liquid (A)), a solution containing at least 0.001% by weight of the Sn(II) compound can be obtained In the solution in the carrier liquid (A), it is considered that the Sn(II) compound is soluble in the carrier liquid (A) selected from non-aqueous polar liquids in which metallic nano-objects are not dispersed.

In the composition according to the present invention, the Sn(II) compounds are preferably present in a certain amount so that the total weight of Sn(II) in the Sn(II) compound relative to the metal nano-object (B) (excluding Sn(II) compound) in a weight ratio of 0.01% to 5%, more preferably 0.01% to 3.9%, further preferably 0.1% to 3.9%, and still more preferably 1% to In the range of 3.9%, the best is in the range of 2.0% to 2.5%.

If the weight of Sn(II) in the ink is too low relative to the weight of the metal nano-object (B), the surface coating of the metal nano-object (B) produced by the Sn(II) compound may not be sufficient to achieve resistance to heat and Oxidative stress and the required protection against reactive chemicals. If the weight of Sn(II) in the ink is too high relative to the weight of the metal nano-object (B), the surface coating of the metal nano-object produced by the Sn(II) compound may become too thick, making the use of such The sheet resistance of the transparent conductive film obtained by the ink may be undesirably high.

Surprisingly, it was found that the presence of Sn(II) compound in the composition according to the present invention, regardless of its anion, can effectively improve the metal nano-objects (B) in the transparent conductive film prepared using the composition according to the present invention The stability of anti-oxidation, anti-thermal stress and anti-reactive chemical substances is limited by Sn(II) compounds satisfying the above-defined criteria, that is, they can be dissolved in the same carrier liquid (A) in which metal nano-objects are not dispersed , And not selected from the group consisting of SnCl ₂ , SnBr ₂ and SnI ₂ .

Preferably, the Sn(II) compounds are selected from the group consisting of tin(II) 2-ethylhexanoate, SnF ₂ , tin(II) acetone and tin(II) methanesulfonate.

The composition according to the invention comprises the carrier liquid (A). The carrier liquid (A) is only a vehicle for wet processing, and does not remain in the transparent conductive film formed of the composition as defined above. The transparent conductive film is formed by their solid components in the ink at 25°C and 101.325 kPa (herein referred to as solid components of the ink). The solid content of the ink contains at least a metallic nano-object (B). Please refer to the following for other solid ingredients as appropriate.

For their Sn(II) compounds which undergo hydrolysis in the presence of water resulting in the formation of insoluble SnO, the important carrier liquid (A) is selected from non-aqueous polar liquids. This applies to, for example, Sn(II) compounds 2-ethylhexanoate tin(II), SnF ₂ and acetylacetone tin(II). Therefore, in this case, the composition according to the present invention preferably contains less than 2% by weight of water based on the weight of the carrier liquid (A), or less than 0.5% by weight, or less than 0.05% by weight, preferably less than 0.02% by weight water. On the other hand, when a Sn(II) compound that is stable in the presence of water is used, for example, tin(II) methanesulfonate, the carrier liquid (A) may be in the form of a mixture of a non-aqueous polar liquid and water.

Preferably, the carrier liquid (A) is selected from alcohols having 1 to 5 carbon atoms, preferably ethanol.

In certain preferred cases, the composition according to the invention comprises the components (A) and (B) as defined above, and further comprises (C) one or more binders. The binders are suspended or dissolved in the carrier liquid (A). Typically, such adhesives are polymers. The polymers are dissolved in the carrier liquid (A) or suspended in the carrier liquid (A). The carrier liquid (A) as defined above and the other polymers dissolved therein are single-phase (that is, form a single phase). The polymer that is substantially insoluble in the carrier liquid (A) is present in the ink in the form of latex (ie colloidal dispersion) or suspended discrete solid particles (such as fibers or polymer beads).

In the transparent conductive film obtained from the ink according to the present invention containing one or more binders (C), these binders (C) form an optically transparent continuous solid phase (referred to herein as a matrix). The substrate adheres to and accommodates metal nano-objects (B) in the transparent conductive film, fills the gaps between the metal nano-objects (B), provides mechanical integrity and stability for the transparent conductive film, and transfers the transparent conductive film Bond to the substrate surface. The metallic nano-objects (B) dispersed in the matrix form a conductive mesh structure, so that electrons can flow between adjacent and overlapping metallic nano-objects in the layer.

Preferred binders are selected from the group consisting of cellulose ethers (eg hydroxypropyl methyl cellulose, methyl cellulose, carboxymethyl cellulose), crystalline cellulose (especially nanocrystalline cellulose), Poly(meth)acrylate, copolymer of acrylate and/or methacrylate, copolymer of styrene and (meth)acrylate, polystyrene, polyacrylamide, polyvinyl alcohol, polyvinylpyrrole Pyridone, polystyrene sulfonic acid, polyester, polyurethane, polycarbonate, gelatin, acrylate-vinyl acetate copolymer, polydextrose and blends thereof. Herein, the term "(meth)acrylic acid" includes "methacrylic acid" and "acrylic acid". For further disclosure of such adhesives, please refer to US 2016/0225483 A1, US 2018/0134908 A1, US 2014/0255707 A1, WO 2016/023887 A1, WO 2016/023904 A1 and WO 2016/023889 A1. Incorporated by reference.

In addition to the ingredients (A) and (B) as defined above and optionally (C), the composition according to the invention optionally contains other ingredients, for example, defoamers, rheology control agents, corrosion inhibitors and Other additives. Typical defoamers, rheology control agents, and corrosion inhibitors are known in the art and are commercially available. It should be understood that the amount of any other ingredients (except for the ingredients (A) and (B) as defined above and (C) as appropriate) of the composition according to the invention (as defined above) and the amount of such other ingredients should be in a certain amount The method is selected so that the conductivity and optical properties of the transparent conductive film obtainable from the composition are not impaired.

The preferred composition according to the first aspect of the invention is a composition in which two or more preferred features as defined above are combined.

A particularly preferred composition according to the invention comprises A) a carrier liquid selected from alcohols having 1 to 5 carbon atoms, preferably silver nanowires in which ethanol (B) is dispersed in the carrier liquid (A) and// Or copper nanowires, wherein the surfaces of the dispersed metal nanowires (B) are at least partially coated with a layer containing one or more Sn(II) compounds selected from the group consisting of Group consisting of: tin (II) 2-ethylhexanoate, SnF ₂ , tin (II) acetone and tin (II) methanesulfonate in which in the composition-based on the total weight of the composition, the The weight fraction of the isometallic nanoparticles (B) is in the range of 0.001 to 5% by weight, more preferably 0.002 to 1% by weight. And/or-the ratio of the weight of Sn(II) in the Sn(II) compound to the weight of the metal nano-object is in the range of 0.01% to 3.9%, more preferably in the range of 2.0% to 2.5%.

The composition according to the invention as defined above is suitable for placing the metal nano-objects (B) on the surface of the substrate, the surface of the metal nano-objects (B) is at least partially coated with one or more as defined above The layer of Sn(II) compound. Therefore, the second aspect of the invention relates to the use of the composition according to the first aspect of the invention as defined above, which is used to dispose the metal nano-objects (B) on the surface of the substrate, wherein The surface of the metallic nano-object (B) is at least partially coated with a layer containing one or more Sn(II) compounds as defined above. With regard to the specific and preferred features of the composition according to the invention, reference is made to the disclosure provided above in the context of the first aspect of the invention.

According to a third aspect of the present invention, there is provided a method for preparing a composition in order to obtain a conductive transparent film comprising a metal nano-object arranged on the surface of a substrate, in particular the combination according to the first aspect of the present invention as defined above Thing. The method includes the following steps: (1) providing or preparing a precursor composition comprising (A) a carrier liquid (B0) selected from a non-aqueous polar liquid, and a metal nanoparticle dispersed in the carrier liquid (A) Object (2) Add one or more Sn(II) compounds to the precursor composition, the one or more Sn(II) compounds can be dissolved in the same carrier liquid (A) in which no metallic nano-objects are dispersed, The limiting condition is that the one or more Sn(II) compounds do not contain any of SnCl ₂ , SnBr ₂ and SnI ₂ .

In the precursor composition provided in step (1), the surface of the metal nanoparticles (B0) is not coated with a layer containing any Sn(II) compound. Only when one or more Sn(II) compounds are added to the precursor composition in step (2), a layer comprising one or more Sn(II) compounds is formed, which at least partially coats the dispersed metals The surface of the nano-object (B0), thereby forming a composition according to the first aspect of the invention as defined above, the composition comprising metallic nano-particles (B) dispersed in a carrier liquid (A), wherein these The surface of the dispersed metal nano-object (B) is at least partially coated with a layer containing one or more Sn(II) compounds as defined above. It is currently assumed that the Sn(II) compound dissolved in the carrier liquid (A) precipitates and/or adsorbs on the surface of the metal nano-object (B0) dispersed in the carrier liquid (A) immediately after adding the precursor composition.

The criteria for selecting the carrier liquid (A), and the preferred carrier liquid (A), as disclosed above, also apply in the context of the first aspect of the invention.

The criteria for selecting the metallic nano-object (B0) and the preferred metallic nano-object (B0), as disclosed above for the metallic nano-object (B), also apply in the context of the first aspect of the invention.

In the precursor composition, the weight fraction of the metal nanoparticles (B0) is preferably in the range of 0.001% to 10% by weight, preferably in the range of 0.001 to 5% by weight based on the total weight of the precursor composition , Preferably in the range of 0.002 to 1% by weight. When the weight fraction of the metal nanoparticles (B0) in the precursor composition is too high, the metal nanoparticles (B0) cannot be well dispersed in the ink. When the weight fraction of metal nanoparticles (B0) in the precursor composition is too low, this method may become inefficient.

In step (2) of the method defined above, the amount of the Sn(II) compounds added is preferably 0.02% to 10% by weight relative to the weight of the metal nano-object (B0) in the precursor composition. More specifically, in step (2) of the method defined above, the Sn(II) compounds are preferably added in an amount such that the total weight of Sn(II) in the added Sn(II) compound is relative to The weight ratio of metal nano-objects (B0) (excluding Sn(II) compounds) in the precursor composition is in the range of 0.01% to 5%, more preferably in the range of 0.01% to 3.9%, and most preferably 2.0% To within 2.5%.

If the weight of the added Sn(II) is too low relative to the weight of the metal nanoparticles (B0) in the precursor composition, the surface coating of the metal nanoparticles (B0) produced by the Sn(II) compound may be insufficient To achieve the required protection against heat and oxidative stress and against reactive chemicals. If the weight of the added Sn(II) is too high relative to the weight of the metal nanoparticles (B0) in the precursor composition, the surface coating of the metal nanoobject produced by the Sn(II) compound may become too thick Therefore, the sheet resistance of the transparent conductive film obtained by using such metal nanoparticles may be undesirably high.

Preferably, in step (2), the Sn(II) compounds are added to the precursor combination in the form of a solution of the Sn(II) compound in the same liquid as the carrier liquid (A) of the precursor composition In which, the weight fraction of Sn(II) in the solution is in each case in the range of 0.001% to 0.5% by weight based on the total weight of the solution, preferably in the range of 0.01% to 0.2% by weight, It is most preferably in the range of 0.01% to 0.1% by weight. Optimally, the carrier liquid (A) of the precursor composition is ethanol, and the Sn(II) compound is added to the precursor composition in the form of a solution of the Sn(II) compound in ethanol, wherein the solution The weight fraction of Sn(II) in each case is in the range of 0.001% to 0.5% by weight based on the total weight of the solution, preferably in the range of 0.01% to 0.2% by weight, and most preferably 0.01% by weight To the range of 0.1% by weight. If the Sn(II) compound is water-soluble and does not hydrolyze to SnO, a solution of the Sn(II) compound in water can be used.

Alternatively, if such a Sn(II) compound is liquid at 25°C and 101.325 kPa (as is the case for example with tin(II) 2-ethylhexanoate), it can be added to the precursor composition in pure form .

The criteria for the selection of Sn(II) compounds, as well as the preferred Sn(II) compounds, as disclosed above, also apply in the context of the first aspect of the invention.

In step (2), after the Sn(II) compound is added, the composition is preferably mechanically stirred to ensure uniform dispersion between the metal nano-object and the added Sn(II) compound. Preferably, this is done by means of vibration, shaking or by using a device selected from the group consisting of static mixers and dynamic mixers.

Silver nanowires (and nanowires of other metals) are typically commercially available in the form of suspensions, where the surface of the silver nanowires is coated with an organic protective agent to stabilize the suspension, that is, to avoid silver The gathering of nanowires. The organic protective agent does not contain any Sn(II) compounds. Typically, the organic protective agent is selected from the group consisting of polyvinylpyrrolidone, polyvinyl alcohol, anionic surfactants (such as sodium lauryl sulfate), laurylamine, hydroxypropyl cellulose and fatty acids. Therefore, in the precursor composition provided in step (1) of the method according to the present invention, the surface of the metal nanowire (B0) is typically coated with a layer of organic protective agent.

Any substance adsorbed on the surface of the metal nano-object (B0) is not included in the definition of the size of the metal nano-object (B0), and is not included in the weight of the metal nano-object (B0) relative to the precursor composition In the weight fraction.

In order to facilitate the replacement of these organic protective agents by the Sn(II) compound added in step (2) of the method according to the present invention, it is preferable to subject the metal nanowires (B0) in the precursor composition to preliminary treatment, This preliminary treatment promotes at least partial replacement of the organic protective agent adsorbed on the surface of the metal nanowires by the Sn(II) compound added in step (2). Therefore, in a particularly preferred method according to the third aspect of the invention, step (1) includes (1.1) Provide or prepare a main precursor composition, the main precursor composition comprising (A0) Carrier fluid (B0) Metal nano-objects dispersed in the liquid, wherein the surface of the dispersed metal nano-objects (B0) is coated with an organic protective agent that does not contain any Sn(II) compound, (1.2) A precursor composition is prepared from the main precursor composition in the following manner: To this main precursor composition, add acetone in an amount of 0.1 ml to 5 ml acetone/mg metal nano-object (B0), remove the supernatant, and redisperse the metal nano-object (B0) in the In the fresh carrier liquid (A) of water-based polar liquid, Add another carrier liquid (A) as needed to adjust the weight fraction of the metal nano-objects (B0). The total weight of the precursor composition is in the range of 0.001% to 10% by weight, preferably 0.001 to 5. Within the range of% by weight, preferably within the range of 0.002 to 1% by weight.

The carrier liquid (A0) of the main precursor solution is typically a liquid that has undergone metal nano object synthesis. In the case of silver nanowires, the carrier liquid (A0) is typically selected from polyols, preferably from the group consisting of ethylene glycol, propylene glycol and glycerin.

In sub-step (1.2) of the preferred method defined above, acetone is added to precipitate the metallic nano-objects. Without wishing to be bound by any theory, it is currently assumed that the preliminary treatment (substep (1.2)) promotes at least partial replacement of the organic protective agent adsorbed on the surface of the metal nanowires by the Sn(II) compound added in step (2). In sub-step (1.2), the carrier liquid (A0) of the main precursor composition is removed and replaced with a fresh carrier liquid (A) selected from non-aqueous polar liquids. By centrifuging the precursor composition at 3000 rpm to 4000 rpm for 2 to 10 minutes, the removal of the supernatant from the main precursor composition can be facilitated.

Commercially available silver nanowire dispersions may contain excess AgCl from silver nanowire preparation. It has been found that chloride anions have an adverse effect on the stability of silver nanowires in transparent conductive films. Such excess AgCl will also be precipitated by adding acetone in substep (1.2). In the case where the main precursor composition contains chloride anions, the preparation of the precursor composition from this main precursor composition (step 1.2) preferably includes the following sub-steps: (1.2.1) Add acetone in an amount of 0.1 ml to 5 ml acetone/mg metal nano-object (B0) to the main precursor composition, (1.2.2) Remove the supernatant and redisperse the metallic nano-object (B0) in a fresh carrier liquid (A) selected from non-aqueous polar liquids, (1.2.3) Add 7 mg to 16 mg of ammonia (in the form of an aqueous solution of ammonium hydroxide)/mg of metal nano-body (B0) and allow the composition to settle for 1 to 10 minutes (1.2.4) Centrifuge the composition obtained in step (1.2.3) at 3000 rpm to 4000 rpm for 2 to 10 minutes, remove the supernatant and redisperse the metal nano-object (B0) in In the fresh carrier liquid (A) of water-based polar liquid, (1.2.5) Repeat the stage (1.2.4) 1 to 5 times as appropriate (1.2.6) Add additional carrier liquid (A) as necessary to adjust the weight fraction of the metal nano-objects (B0). The total weight of the precursor composition is in the range of 0.001% to 10% by weight. It is preferably in the range of 0.001% to 5% by weight, most preferably in the range of 0.002 to 1% by weight.

Any AgCl precipitated by adding acetone in sub-step (1.2.1) is redissolved by adding ammonium hydroxide in sub-step (1.2.3) so that it can be dissolved in sub-step (1.2.4) Remove with the supernatant. In the substep (1.2.3), ammonia is preferably added in the form of an aqueous solution of ammonium hydroxide, which contains 2.5% to 5% by weight of ammonia NH ₃ , preferably about 4% by weight of ammonia.

The preferred method according to the third aspect of the present invention is a method in which two or more preferred features as defined above are combined.

A particularly preferred method according to the invention comprises the following step (1) providing a precursor composition comprising (A) a carrier liquid selected from alcohols having 1 to 5 carbon atoms, preferably ethanol ( B0) Silver nanowires and/or copper nanowires dispersed in the carrier liquid (A), wherein the weight fraction of the metal nano-objects (B0) is 0.001% by weight based on the total weight of the precursor composition It is in the range of 5% by weight, more preferably in the range of 0.002% by weight to 1% by weight. (2) Add a certain amount of one or more selected from the group consisting of tin (II) 2-ethylhexanoate, SnF ₂ , tin (II) acetone and tin (II) methanesulfonate to the precursor composition Group of Sn(II) compounds in an amount such that the total weight of Sn(II) in the added Sn(II) compound relative to the weight of the metal nano-object (B0) in the precursor composition is 0.01% to 3.9 % Range, more preferably in the range of 2.0% to 2.5%.

According to a fourth aspect of the present invention, there is provided an article comprising a substrate having a surface, and a plurality of (B) metal nano-objects arranged on the surface of the substrate, wherein the surfaces of the metal nano-objects are at least Partially coated with a layer containing one or more Sn(II) compounds, with the proviso that the layer does not contain any of SnCl ₂ , SnBr ₂ and SnI ₂ .

In the article, the plurality of metallic nano-objects (as appropriate combined with other substances such as adhesives) form a transparent conductive film arranged on the surface of the substrate.

The thickness of the layer containing one or more Sn(II) compounds on the surface of the metal nanoparticles (B) is less than 10 nm, preferably less than 5 nm, further preferably less than 3 nm, and most preferably about 1 nm, such as Measured by high resolution transmission electron microscopy (HRTEM).

The criteria for selecting the metallic nano-object (B) and the preferred metallic nano-object (B), as disclosed above for the metallic nano-object (B), are also applicable in the context of the first aspect of the invention.

In the transparent conductive film of the product according to the present invention, the (equal) Sn(II) compound is preferably present in a certain amount, so that the total weight of Sn(II) in the Sn(II) compound is relative to the metal nano-object ( B) (Excluding Sn(II) compound) The weight ratio is in the range of 0.01% to 5%, more preferably in the range of 0.01% to 3.9%, more preferably in the range of 2.0% to 2.5%. If the weight of Sn(II) is too low relative to the weight of metallic nano-object (B), the surface coating of metallic nano-object (B) produced by Sn(II) compound may not be sufficient to achieve resistance to thermal and oxidative stress And the necessary protection against reactive chemicals. . If the weight of Sn(II) is too high relative to the weight of the metal nano-object (B), the surface coating of the metal nano-object (B) produced by the Sn(II) compound may become too thick, therefore, contains The sheet resistance of the transparent conductive film of such metal nano-objects may be undesirably high.

It has surprisingly been found (as demonstrated by the examples presented below) that the presence of Sn(II) compounds in the articles according to the invention, regardless of their anions, can effectively enhance the metal nano-objects (B ) The stability of anti-oxidation, anti-thermal stress and anti-reactive chemicals is limited by the fact that Sn(II) compounds are not selected from the group consisting of SnCl ₂ , SnBr ₂ and SnI ₂ .

The Sn(II) compound is preferably selected from the group consisting of tin (II) 2-ethylhexanoate, SnF ₂ , tin (II) acetone, tin (II) methanesulfonate, and SnO. By calcining the metal nano-objects at least partially coated with a layer containing tin (II) 2-ethylhexanoate under annealing (see below for details), or by hydrolyzing Sn(II) compounds (eg 2 tin(II) ethylhexanoate, SnF ₂ , tin(II) acetone, tin(II) methanesulfonate), can be selected from Sn(II) compounds (eg tin(II) 2-ethylhexanoate) Get SnO.

The substrate preferably includes a material selected from the group consisting of plastic, glass, metal, silicon, and sapphire. The substrate is preferably in the form selected from the group consisting of foils, films, webs, sheets and plates. Preferably, the thickness of the substrate is in the range of 10 μm to 200 μm, preferably in the range of 50 μm to 100 μm. In certain cases, the substrate includes an optically transparent material selected from the group consisting of glass and organic polymers, which is electrically insulating.

Preferred glass types are, for example, float glass, low-iron float glass, thermally strengthened glass, and chemically strengthened glass. As the case may be, the glass has a low-emissivity (low-emission) coating, a sunscreen coating, or any other coating on the surface facing away from the transparent conductive film.

Preferred organic polymers are selected from the group consisting of polymethyl methacrylate (PMMA, commercially available, such as Plexiglas ^™ ), polycarbonate (PC), polyethylene (PE), and low density polyethylene (LDPE) , Linear low density polyethylene (LLDPE), polypropylene (PP), low density polypropylene (LDPP), polyethylene terephthalate (PET), ethylene glycol modified polyethylene terephthalate , Polyethylene naphthalate (PEN), cellulose acetate butyrate, polylactide (PL), polystyrene (PS), polyvinyl chloride (PVC), polyimide (PI), polyepoxy Propane (PPO) and its mixtures. PET and PEN systems are particularly preferred.

Preferably, the light transmittance of the substrate is 80% or higher, more preferably 90% or higher, further preferably 95% or higher, in each case according to ASTM D1003 published in November 2013 (Procedure A) Measurement.

Preferably, the sheet resistance of the article according to the invention is in the range of 10 ohms/square to 150 ohms/square, such as by placing on the plurality of metallic nano-objects (B) placed on the surface of the substrate The four-point probe is measured at a temperature of 25°C and a pressure of 101.3 kPa.

其中R_sh 係薄層電阻。因此，薄層電阻R_sh 係

在上面給出之公式中，體電阻R乘以無量綱量（W/L）以獲得薄層電阻R_sh ，因此薄層電阻之單位係歐姆。為了避免與體電阻R混淆，薄層電阻值通常表示為「每平方歐姆」（歐姆/平方），因為在正方形薄片之特定情況下，W = L且R = R_sh 。薄層電阻係藉助於置放於該透明導電薄膜上之四點探針量測的，該透明導電薄膜包含安置在基板表面上之該複數個金屬奈米物體（B）。Sheet resistance (sometimes referred to as "square resistance") is a measure of the resistance of a thin body (thin sheet, that is, of uniform thickness). The transparent conductive film as described herein can be regarded as such a sheet-like thin body. The term "sheet resistance" means that the current flows along the plane of the sheet, rather than perpendicular to the plane of the sheet. For a sheet with thickness t, length L and width W, the resistance R is

Where R _sh is the sheet resistance. Therefore, the sheet resistance R _sh

In the formula given above, the volume resistance R is multiplied by the dimensionless quantity (W/L) to obtain the sheet resistance R _sh , so the unit of the sheet resistance is ohms. To avoid confusion with the bulk resistance R, the sheet resistance value is usually expressed as "ohms per square" (ohm/square), because in the specific case of a square sheet, W = L and R = R _sh . The sheet resistance is measured by means of a four-point probe placed on the transparent conductive film, which contains the plurality of metallic nano-objects (B) placed on the surface of the substrate.

Further preferably, the article according to the invention has -80% or higher light transmittance, as measured according to ASTM D1003 (Procedure A) And/or -Haze of 3% or less, as measured according to ASTM D1003 (Procedure A).

The measurement of haze and light transmittance by means of a haze meter is defined as "Procedure A-Haze Meter" in ASTM-D1003 published in November 2013. The haze and light transmittance values given in the context of the present invention refer to this procedure.

The parameter "transmittance" refers to the percentage of incident light that passes through the medium (in the case of the article according to the invention, through the substrate and the transparent conductive film disposed on the substrate). In ASTM D1003 published in November 2013, the light transmittance is called the light transmittance, which is the ratio of the light flux transmitted by the body to the light flux incident on the body.

Preferably, the light transmittance of the article according to the present invention (corresponding to the light transmittance defined in ASTM D1003 published in November 2013) is 85% or higher, more preferably 90% or higher, and further preferred 95% or higher, measured in each case according to ASTM D1003 (Procedure A) published in November 2013 (corresponding to the light transmittance defined in ASTM D1003 published in November 2013).

Generally, the parameter haze is the index of light diffusion. It refers to the percentage of the amount of light that is separated from the incident light and scattered during transmission. Unlike light transmittance, light transmittance is largely due to the nature of the medium. Haze is usually a production problem and is typically caused by surface roughness and unevenness of particles or composition embedded in the medium.

According to ASTM D1003 published in November 2013, haze is the light scattering of the sample, which causes the contrast of the object observed through the sample to be reduced, that is, the scattering causes the direction to deviate from the direction of the incident beam by more than a specific angle (2.5°) The percentage of transmitted light.

Preferably, the haze of the product according to the invention is 1.8% or less, more preferably 1.5% or less, further preferably 1% or less, in each case according to the publication in November 2013 ASTM D1003 (Procedure A) measurement.

Further preferably, the article according to the invention (as defined above) exhibits one or more of the following characteristics:

-The sheet resistance is in the range of 10 ohms/square to 60 ohms/square, as measured by a four-point probe on the plurality of metallic nano-objects (B) placed on the surface of the substrate.

-Haze is 3% or less, as measured according to ASTM D1003 (Procedure A) published in November 2013,

-The light transmittance is 90% or higher, as measured according to ASTM D1003 (Procedure A) published in November 2013.

Preferably, in the article according to the present invention, the coverage of the plurality of metal nano-objects (B) on the substrate surface is in the range of 10% to 65%, preferably in the range of 15% to 35%. In order to calculate the coverage rate, an image of the surface on which the plurality of metal nano-objects are placed is taken by an optical microscope or a scanning electron microscope, and the image is analyzed with the help of image analysis software, which can distinguish between the images The exposed surface of the metal nano-object (B) and the substrate, and calculate the fraction of the surface covered by the metal nano-object (B).

Preferably, in the product according to the present invention, the metal nano-objects (B) are 1 mg/m ² to 1000 mg/m ² , preferably 5 mg/m ² to 200 mg/m ² , most preferably A concentration of 20 mg/m ² to 50 mg/m ² exists on the surface of the substrate.

In a particularly preferred article according to the invention, the plurality of metallic nanowires (B) are incorporated into an optically transparent matrix formed of one or more binders (C) as defined above. Therefore, the preferred article includes a substrate having a surface, and a plurality of metallic nano-objects (B) as defined above arranged on the surface of the substrate, and the article further includes one or more on the surface of the substrate Adhesive (C) as defined above. The metallic nano-object (B) is dispersed in the matrix formed by the binders. The substrate adheres and accommodates the metal nano-objects (B) in the transparent conductive film, fills the gaps between the metal nano-objects, provides mechanical integrity and stability for the transparent conductive film, and bonds the transparent conductive film to the substrate On the surface.

The selection criteria for adhesives and the preferred adhesives, as disclosed above, also apply in the context of the first aspect of the invention.

The preferred product according to the fourth aspect of the present invention is a product in which two or more preferred features as defined above are combined.

A particularly preferred article according to the invention comprises a substrate having a surface, wherein the substrate comprises one or more materials selected from the group consisting of glass and organic polymers, and the light transmittance is 80% or higher, as per ASTM Measured by D1003 (Procedure A). -And a plurality of (B) silver nanowires and/or copper nanowires arranged on the surface of the substrate, wherein the surface of the nanowires (B) is at least partially coated with one or more Sn (II) A layer of compound, the one or more Sn(II) compounds are selected from the group consisting of tin (II) 2-ethylhexanoate, SnF ₂ , tin (II) acetone, tin mesylate ( II) and SnO where the total weight of Sn(II) in the Sn(II) compound relative to the weight of the metal nano-object (B) (excluding Sn(II) compound) is in the range of 0.1% to 3.9%, more It is preferably in the range of 2.0% to 2.5%. Such preferred products typically exhibit sheet resistance and optical parameters (transmittance and haze) that fall within the ranges defined above.

According to a fifth aspect, the invention relates to the use of the product according to the invention for devices selected from the group consisting of: optoelectronic devices, solar cells, touch screens, wearable electronic devices, heaters, displays, Piezoelectric generator and electrochromic window. For specific and preferred features of the article according to the invention, reference is made to the disclosure provided above in the context of the fourth aspect of the invention.

According to a sixth aspect, the invention relates to a method for preparing an article according to the fourth aspect of the invention. The method includes the following steps -Forming a wet film by applying the composition according to the first aspect of the present invention to the surface of the substrate or the surface of the temporary support, -Removing the carrier liquid (A) of the composition from the wet film formed on the surface of the substrate or on the surface of the temporary support -Leave the solid component of the composition according to the first aspect of the invention on the surface of the substrate, or transfer the solid component of the composition according to the first aspect of the invention from the surface of the temporary support to The substrate surface.

For specific and preferred features of the composition according to the first aspect of the invention, refer to the disclosure provided above in the context of the first aspect of the invention.

According to the first aspect of the present invention, the solid content of the composition (ink) includes at least a metal nano-object (B), wherein the surface of the metal nano-object (B) is at least partially coated with one or more Sn(II) compound layer. For other solid components of the composition optionally selected, refer to the disclosure provided above in the context of the first aspect of the invention.

In this method, by applying the composition (ink) according to the first aspect of the present invention to the surface of the substrate or the surface of the temporary support, a wet film is formed on the surface. Next, the carrier liquid (A) of the composition is removed from the wet film formed on the surface of the substrate or the surface of the temporary support.

The criteria for selecting substrates and the preferred substrates, as disclosed above, also apply in the context of the fourth aspect of the invention. The temporary support is a support that provides favorable conditions for the removal of the carrier liquid (A), but it is not suitable for use as a substrate in an article as defined above in the context of the fourth aspect of the invention.

In the case of applying ink to the temporary support, after removing the carrier liquid (A), the solid content of the ink is transferred from the surface of the temporary support to the surface of the substrate. The method including transferring the solid content of the ink from the temporary support to the (permanent) substrate is also called the transfer coating method.

In the case of applying ink to the substrate, after removing the carrier liquid (A), the solid content of the ink remains on the surface.

In a preferred specific method according to the sixth aspect of the invention, a temporary support in the form of a filtration membrane is used, and the carrier liquid (A) is removed by means of filtration. Therefore, the preferred specific method includes the following steps -By applying the composition according to the first aspect of the present invention to the surface of the filter membrane, thereby forming a wet film on the surface of the filter membrane, -The carrier liquid (A) of the composition is removed from the wet film formed on the surface of the filter membrane by filtration, so that a filter containing the metal nano-objects (B) is formed on the surface of the filter membrane The residue -Transfer the filtering residue to the surface of the substrate, thereby placing the metallic nano-objects (B) on the surface of the substrate.

Preferably, the filtration is achieved by reducing the pressure below the filter membrane, preferably by applying a vacuum (vacuum filtration) under the filter membrane. Such filtering techniques are well known in the art.

Typically, the filtration membrane is a hydrophobic polymer membrane, wherein the polymer is preferably selected from fluorinated polymers, most preferably polytetrafluoroethylene PTFE, and has a pore size of 100 to 80 nm. Suitable membrane systems are commercially available. The pore diameter is larger than the diameter of the metal nanowire but smaller than the length of the metal nanowire. The metal nanowire cannot pass through the hole because the metal nanowire is aligned on the filter membrane with its length perpendicular to the hole (which is greater than the pore size) due to the force of the vacuum applied from below the filter membrane.

When the solid component intended to be included in the transparent conductive film is dissolved in the carrier liquid (A), for example, the binder (C) is dissolved in the carrier liquid (A), a method involving removing the carrier liquid (A) by means of filtration is Inappropriate. Therefore, in another preferred specific method according to the sixth aspect of the invention, a wet film is formed on the surface of the substrate as defined above in the context of the fourth aspect of the invention, and The carrier liquid (A) is removed from the membrane so that when the carrier liquid (A) is removed from the wet membrane, the solid components dissolved in the carrier liquid (A) remain on the surface of the substrate.

Therefore, the preferred specific method includes the following steps -By applying the composition according to the first aspect of the present invention to the surface of the substrate, a wet film is formed on the surface of the substrate -Removing the carrier liquid (A) from the wet film formed on the surface of the substrate by evaporation.

This method is most suitable for the case where the ink contains solid components dissolved in the carrier liquid (A), for example, the binder (C) dissolved in the carrier liquid (A).

Preferably, the composition according to the invention is applied to the surface of the substrate by coating or printing, preferably by a coating technique selected from the group consisting of: roll coating, slit-type extrusion Coating, spray coating, ultrasonic spraying, dip coating and blade coating, or applied by a printing technique selected from the group consisting of inkjet printing, pad printing, lithographic printing, gravure printing, screen printing, Gravure printing and single piece continuous printing.

Preferably, the thickness of the wet film formed by applying the composition according to the present invention to the surface of the substrate is in the range of 1 μm to 100 μm, preferably in the range of 2 μm to 50 μm. This thickness is also called "wet thickness".

By exposing the wet film to a temperature in the range of 20 °C to 120 °C, preferably in the range of 40 °C to 120 °C, most preferably in the range of 80 °C to 120 °C, from the surface of the substrate The carrier liquid (A) is removed from the wet film, so that the carrier liquid (A) evaporates, thereby forming a transparent conductive film on the surface of the substrate.

In some specific cases, the method according to the sixth aspect of the present invention further includes the steps of: at a temperature ranging from 140°C to 200°C, preferably 140°C to 160°C, in an air atmosphere Next, the metal nano-objects (B) are annealed on the surface of the substrate for a duration of 10 minutes to 60 minutes, preferably 20 minutes to 40 minutes. It should be noted that annealing can be used to improve the electronic conductivity of transparent conductive films containing a plurality of metal nano-objects (B), wherein the surfaces of the metal nano-objects are at least partially coated with one or more Sn( II) The layer of the compound, but it is not a prerequisite for the desired effect of protecting the metallic nano-object (B) from oxidation. It is also noted that for metal nano-objects whose surface is not coated with a layer containing any Sn(II) compound, the corresponding annealing treatment typically causes a reduction in electronic conductivity due to thermal and oxidative stress (see the comparative example below) ).

By annealing, Sn(II) compounds such as tin(II) 2-ethylhexanoate are calcined to SnO, which is partially but not completely oxidized to SnO ₂ . Therefore, after annealing, the surface of the metal nano-object (B) is at least partially coated with a layer containing mixed oxides of SnO and SnO ₂ . Due to the presence of SnO, the annealed metal nano-object (B) is still at least partially coated with a layer containing Sn(II) compound (ie SnO). The presence of Sn(II) and Sn(IV) in the transparent conductive film that has been subjected to the annealing treatment as defined above can be detected by means of X-ray photon spectroscopy (XPS), see the examples below. Surprisingly, even after annealing in an air atmosphere, the fraction of Sn(II) is significantly greater than that of Sn(IV). Generally, skilled trade unions expect that annealing in an air atmosphere will cause Sn(II) to be substantially completely oxidized to Sn(IV).

The seventh aspect of the invention relates to the use of a Sn(II) compound in the preparation of the composition according to the first aspect of the invention.

The guidelines regarding the selection of a suitable Sn(II) compound and the preferred Sn(II) compounds, as disclosed above, also apply in the context of the fourth aspect of the invention.

Surprisingly, it has been found that using the Sn(II) compound to at least partially coat the surface of metal nanoparticles dispersed in a carrier liquid (A) selected from non-aqueous polar liquids can effectively enhance the inclusion of these metal nanoparticles The stability of the transparent conductive film of the object is resistant to oxidation, thermal stress and anti-reactive chemicals. The limiting condition is that the Sn(II) compound satisfies the criteria defined above, and is soluble in the same in which no metallic nano-objects are dispersed. The carrier liquid (A) is not selected from the group consisting of SnCl ₂ , SnBr ₂ and SnI ₂ .

The invention will now be further described by means of non-limiting examples.

Examples 1. Preparation of ink according to the invention and comparative ink

The ink according to the first aspect of the present invention (as defined above) includes a plurality of silver nanowires (B) dispersed in ethanol (A), wherein the surface of the dispersed silver nanowires (B) is at least partially Is coated with a layer containing a Sn(II) compound selected from the group consisting of tin(II) 2-ethylhexanoate, SnF ₂ , tin(II) acetone and tin(II) methanesulfonate In groups, the ink is prepared by the method according to the third aspect of the present invention as described above. 1.1 Preparation of precursor composition for use in the method according to the invention (step (1))

A main precursor composition containing 0.44% by weight of silver nanowires (B0) in ethylene glycol (a solvent used to synthesize silver nanowires) is provided (step 1.1). In the main precursor composition, the surface of the dispersed metal nano-objects (B) is coated with a layer of polyvinylpyrrolidone PVP (organic protective agent). The average length of the silver nanowire is 100 μm, and the average diameter is 50 nm.

Add 10 to 15 ml of acetone to 2.5 ml of this main precursor composition (step 1.2.1) to allow the silver nanowire to settle at the bottom of the container. Remove the supernatant and re-disperse the silver nanowires in 10 ml of ethanol (step 1.2.2). Add 0.5 ml of ammonium hydroxide aqueous solution (containing 4% by weight of ammonia) to the silver nanowire (B0) obtained in step (1.2.2) and redisperse it in ethanol to dissolve in step (1.2.1) Any AgC precipitated by the CCP and the composition was allowed to settle for 2 minutes (step 1.2.3). Next, 40 ml of ethanol was added, and the resulting composition was centrifuged at 3500 rpm for 5 minutes. Remove the supernatant and re-disperse the silver nanowires in ethanol (step 1.2.4). The centrifugation/redispersion step was repeated twice (step 1.2.5). After the last centrifugation and removal of the supernatant, the silver nanowires were resuspended in 30 ml of ethanol (carrier liquid (A)), and this composition was used for preparation using the third aspect according to the present invention Pre-ink precursor composition. 1.2 Add Sn(II) compound (step (2))

1.3製備比較墨水To the precursor composition obtained as described in section 1.1 above, a Sn(II) compound (dissolved in ethanol or water, or in liquid form) selected from Table 1 is added. After the Sn compound is added, the composition is shaken so as to be uniformly dispersed. Thus, an ink according to the first aspect of the present invention (as described above) is obtained, the ink containing (A) ethanol (carrier liquid), and (B) silver nanowires dispersed in the carrier liquid (A), The surface of the dispersed silver nanowires (B) is at least partially coated with a layer containing a Sn(II) compound selected from the group consisting of tin 2-ethylhexanoate ( II), SnF ₂ , acetyl tin acetone (II) and tin (II) methanesulfonate. Table 1

1.3 Preparation of comparative ink

The ink obtained in the same manner as described above for the precursor composition (item 1.1) was used for comparative experiments. 2. Preparation of products according to the invention and comparative products

The transparent conductive films each include a plurality of silver nanowires (B), wherein the surface of the silver nanowires (B) is at least partially coated with a layer containing a Sn(II) compound selected from the group consisting of The group consisting of: tin (II) 2-ethylhexanoate, SnF ₂ , tin (II) acetone, tin (II) methanesulfonate, and SnO, these transparent conductive films utilize the above-described according to the present invention The method of the sixth aspect is prepared on the pre-cleaned surface of the glass substrate.

The 20 ml ink according to the first aspect of the present invention contains (A) ethanol (carrier liquid), and (B) silver nanowires dispersed in the carrier liquid, wherein the dispersed silver nanowires (B) The surface is at least partially coated with a layer containing tin (II) 2-ethylhexanoate, SnF ₂ , tin (II) acetone, or tin (II) methanesulfonate. The weight fraction of the silver nanowires is ink The total weight is 0.002% by weight, and the ink is applied to the surface of the temporary support in the form of a hydrophobic filter made of polytetrafluoroethylene (Sartorius 11806-47-N, pore diameter 450 nm, diameter 47 mm ). While pouring ink onto the filter membrane, no pressure drop was applied under the filter membrane. Therefore, a wet film is formed on the surface of the filter film on which the ink is poured.

Next, by means of vacuum filtration, ethanol is removed from the wet film formed on the surface of the filter membrane (the carrier liquid of ink (A)), so that the silver nanowires (B) containing the silver nanowires are formed on the surface of the filter membrane The filtering residue, in which the silver nanowires (B) form an interconnected network structure. Before the filter residue on the filter membrane is completely dried, the filter residue is transferred to the surface of the pre-cleaned glass substrate by pressing the glass substrate onto the filter residue placed on the filter membrane A vacuum is applied under the filter membrane, thereby forcing the filter residue into close contact with the glass substrate. Finally, remove the vacuum and lift off the filter membrane.

A comparative product was obtained in the same manner using the comparative ink described in Section 1.3 above. 3. Test results

Regarding the effect of heat and/or oxidation treatment or exposure to H ₂ S on the appearance, composition and electrical conductivity (sheet resistance) of the transparent conductive film, the products according to the present invention and comparative products were examined. 3.1 Heat treatment under ambient air

The product according to the present invention and the comparative product (with a transparent conductive film containing a silver nanowire not coated with a layer containing any Sn(II) compound) at different temperatures (100°C, 200°C or 300°C, as shown below ) Annealing in a conventional oven for 30 minutes under ambient air. In each product, the transparent conductive film is arranged on the surface of the glass substrate, as described in Section 2 above.

Before and after annealing (product cooling after annealing), the transparent conduction is studied by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscope (HRTEM) The appearance of silver nanowires in the film. Before annealing and after annealing (after annealing the product is cooled), the crystal structure of silver in the transparent conductive film was studied by means of X-ray diffraction (XRD).

Before annealing and after annealing (after the annealed product is cooled), the composition of the transparent conductive film is studied by means of Raman spectroscopy and X-ray photoelectron spectroscopy (XPS).

Before annealing and after annealing (after cooling of the annealed product), the sheet resistance of the transparent conductive film was measured by means of a four-point probe at a temperature of 25°C and a pressure of 101.3 kPa. On the plurality of metallic nano-objects (B) on the surface of the substrate.

Before annealing and after annealing (after cooling of the annealed product), according to ASTM D1003, procedure A, the Shimadzu UV3600 UV-VIS-NIR spectrometer was used to determine the light transmittance of the product.

The transparent conductive film includes a plurality of silver nanowires (B), wherein the surface of the silver nanowires (B) is at least partially coated with a layer containing tin (II) 2-ethylhexanoate, the transparent conductive film The SEM image (Figure 1a) shows that the silver nanowires are uniformly dispersed and exist in high purity without the presence of other particles. In the enlarged SEM image (Figure 1b), the connection between individual silver nanowires can be observed, demonstrating sufficient contact between individual silver nanowires. No breakage of silver nanowires was observed.

The TEM image (Figure 1c) obtained after annealing at 200°C for 30 minutes and subsequent cooling showed that the silver nanowires clearly had a core-shell structure, and the HRTEM image (Figure 1d) showed a thin shell with a thickness of less than 2 nm. Evenly distributed on the surface of the silver nanowires, it was confirmed that the silver nanowires were uniformly coated.

Raman spectrum of the product according to the present invention (Figure 2a) (during the step (2) of the method of manufacturing ink (see section 1.2 above) 0.3 μl or 0.5 μl tin (II) 2-ethylhexanoate is added) It was confirmed that SnO _x (a mixed oxide of SnO and SnO ₂ ) was present on the surface of the silver nanowire after annealing. Contrary to the Raman spectrum of the comparative product (labeled "AgNWs"), the Raman spectrum of the product according to the present invention has two different Raman vibration peaks at 1374 and 1602 cm ^-1 due to Sn-O bond vibration. When the amount of tin (II) 2-ethylhexanoate added in step (2) of the method of manufacturing ink increases, the intensity of these peaks increases.

XPS analysis (Figure 2b) was performed to identify the elemental composition at the surface of the silver nanowires in the product according to the present invention, the product according to the present invention was obtained using ink, and during step (2) of the method for manufacturing ink ( See section 1.2 above) Add 0.5 μl of tin (II) 2-ethylhexanoate. In addition to the peak of element Ag, the peaks of elements Sn, C and O can also be clearly observed, see FIG. 2b. The high-resolution XPS diagram of Sn (not shown) exhibits a larger Sn ²⁺ peak, but Sn ⁴⁺ has only a weak signal. Obviously, despite the annealing treatment in an air atmosphere, most of the detectable Sn is Sn(II) rather than oxidized to Sn(IV).

The article (1) has a transparent conductive film containing a plurality of silver nanowires (B), wherein the surface of the silver nanowires (B) is at least partially coated with tin (II) containing 2-ethylhexanoate Layer, the product (2) has a transparent conductive film containing a plurality of silver nanowires (B), wherein the surface of the silver nanowires (B) is at least partially coated with a layer containing SnF ₂ and the comparative product has A transparent conductive film containing silver nanowires, which are not coated with a layer containing any Sn(II) compound, and the product (1) and product (2) and the comparative product are annealed at 300°C for 30 minutes.

The SEM images of these products before annealing (Figure 3a, c, e) did not show the transparent conductive film of the comparative product (Figure 3a) and the transparent conductive film of the products (1) (Figure 3c) and (2) (Figure 3e) Significant differences between. In each case, a number of mechanically complete silver nanowires were observed, which were evenly dispersed and highly interconnected. After annealing, the silver nanowires in the transparent conductive films of the products (1) (FIG. 3d) and (2) (FIG. 3f) basically maintained their original shapes, while in the comparative products, the nanowires were destroyed, and An island-like droplet-like aggregate with a larger diameter than the original silver nanowire was formed, and the original silver nanowire was almost undetectable in the SEM image (Figure 3b). Therefore, SEM images (Figures 3c-f) show that in the article according to the present invention, even after annealing at 300°C for 30 minutes, the silver nanowires substantially maintain their original shape.

In the XRD pattern of the comparative product after annealing, compared with the XRD pattern of the comparative product before annealing, the intensity of the diffraction peak attributable to silver is significantly enhanced (Figure 4a). This is believed to be the result of the melting of the silver nanowires during annealing, which results in the formation of Ag particles with a larger size and increased crystallinity after cooling. In contrast, the annealing treatment obviously does not cause any significant change in the diffraction peak caused by silver in the XRD pattern of the product (1), thus confirming the thermal stability of the silver nanowires in the product according to the present invention. (Figure 4b).

A series of articles according to the invention with a conductive transparent film are obtained by applying inks with different weight fractions of silver nanowires (B) (0.002% to 0.5% by weight), wherein the silver nanowires (B ) Is at least partially coated with a layer containing tin (II) 2-ethylhexanoate. In each case, the same volume of ink (20 ml) was applied to obtain a transparent conductive film with different amounts of silver nanowires per unit substrate surface area. These products were annealed at 100°C for 30 minutes in an air atmosphere.

In this series of products according to the present invention, the higher the sheet resistance and light transmittance (see FIG. 5a), the lower the amount of silver nanowires per unit surface area of the substrate. Annealing at 100°C in an air atmosphere seems to have little effect on light transmittance, but causes a modest increase in sheet resistance, which is more pronounced when the amount of silver nanowires per unit substrate surface area is lower. However, in each case, the sheet resistance and light transmittance have acceptable values that fall within the preferred ranges defined above.

The product obtained by adding 0.3 μl of tin (II) 2-ethylhexanoate (II) ink during the step (2) of the method for manufacturing ink (see section 1.2 above) and the comparative product are continuously heated to 300°C and monitored Sheet resistance (see Figure 5b). The sheet resistance of the comparative product (labeled "AgNWs film", left part of Fig. 5b) continued to increase, reaching a temperature range of 180°C to 200°C, at which point it began to increase dramatically. At room temperature, the initial sheet resistance of the product according to the present invention (right part of FIG. 5b) is higher than that of the comparative product, but decreases sharply when the temperature increases. After the sheet resistance increases intermittently but is still below the initial value, the sheet resistance decreases significantly in a temperature range between about 150°C and 200°C. After reaching 300°C, the temperature was kept at this value, and a further decrease in resistance was observed. Therefore, annealing in an air atmosphere at a high temperature above 100°C can be used to reduce the sheet resistance of the article according to the invention. It must be noted that the results shown in Figure 5b are obtained under dynamic conditions and therefore cannot be directly applied to static conditions. By further testing under static conditions (annealing at a constant temperature for 30 minutes), the results show that when the annealing temperature is in the range of 140°C to 160°C, the sheet resistance is significantly reduced. 3.2 Oxidation treatment

The product according to the present invention and the comparative product were subjected to oxidation by placing each product to be tested in an O ₂ /O ₃ mixture (O ₃ concentration of 0.5% by volume) in a sealed tube furnace at 150° C. for 1 hour. stress. In each product, the transparent conductive film is arranged on the surface of the glass substrate, as described in Part 2 above.

Before the oxidation treatment and after the oxidation treatment (after the product is cooled), the composition of the transparent conductive film is studied by means of Raman spectroscopy and X-ray photoelectron spectroscopy (XPS).

Before the oxidation treatment and after the oxidation treatment (after the product is cooled), by means of a four-point probe placed on the plurality of metal nano-objects (B) placed on the substrate surface at a temperature of 25°C and 101.3 The sheet resistance of the transparent conductive film was measured under the pressure of kPa.

The article (3) has a transparent conductive film containing a plurality of silver nanowires (B), wherein the surface of the silver nanowires (B) is at least partially coated with a layer containing SnF ₂ , the article (3) and The comparative product was subjected to the above-mentioned oxidation treatment.

The XPS plot of the comparative product (marked as "AgNWs") recorded before the oxidation treatment showed a peak attributable to silver and a peak attributable to carbon or oxygen derived from trace surface protective agent PVP (Figure 6a) However, the XPS pattern of the product (3) according to the present invention shows additional peaks attributable to Sn and F (Figure 6b). As a result of the oxidation treatment of the comparison product, the Ag peak in the XPS diagram shifted significantly, indicating the oxidation of silver in the silver nanowire (Figure 6c). On the contrary, after the oxidation treatment of the product (3), the Ag peak in the XPS diagram did not change, indicating that the silver nanowires were not oxidized (Figure 6d). Most interestingly, after the oxidation treatment of the product (3), the Sn ²⁺ peaks in the XPS chart (Figures 6e and 6f) did not change. Before and after the oxidation treatment, the high-resolution XPS diagrams of Sn (Figures 6e and 6f) showed a large Sn ²⁺ peak, but Sn ^{4+ had} only a weak signal (dashed line). Obviously, most detectable Sn is still Sn(II) and not oxidized to Sn(IV).

Products (4), (5) and (6) are used by adding 2 different amounts (0.3 μl, 0.5 μl and 1 μl respectively) in step (2) of the method of manufacturing ink (see section 1.2 above) -Obtained from an ink made of tin (II) ethylhexanoate, these products (4), (5) and (6) and comparative products are subjected to the above-mentioned oxidation treatment. In the products (4), (5) and (6), the thickness of the layer containing tin (II) 2-ethylhexanoate on the surface of the silver nanowires varies during the step (2) of the method of manufacturing ink (See section 1.2 above) The amount of tin (II) 2-ethylhexanoate added increases with increasing.

Before the oxidation treatment, the sheet resistance of the comparative article (see FIG. 7) was lower than that of the article according to the present invention, because the silver nanowire in the comparative article was not coated with a layer containing Sn(II) compound. However, for the comparative product, a significant increase in sheet resistance after the oxidation treatment was observed. In contrast, for the products (4) and (5), the sheet resistance was observed to increase only slightly by 10 ohms/square, showing good anti-oxidation stability even under harsh conditions. Since the weight of the tin (II) 2-ethylhexanoate added in step (2) is higher than the weight of the silver nanowire (B0) in the precursor composition (see section 1.2 above), the annealing Previously, the product (6) showed higher sheet resistance. Obviously, in the product (6), the coating layer on the surface of the silver nanowire produced by tin (II) 2-ethylhexanoate is quite thick, so the sheet resistance of the transparent conductive film obtained using this ink is quite high. In addition, the significant increase in the sheet resistance of the product (6) after oxidation treatment indicates that the presence of tin (II) 2-ethylhexanoate in the product (6) does not provide sufficient protection against the oxidative stress applied in this test . Interestingly, among the products (4) to (6), the product (5) obtained by using ink made by adding 0.5 μl tin (II) 2-ethylhexanoate had the lowest thickness before and after the oxidation treatment Layer resistance, and products (4) and (6) obtained using inks made by adding lower or higher amounts of tin (II) 2-ethylhexanoate (0.3 μl or 1 μl) show higher Sheet resistance. This proves that the ratio of the weight of Sn(II) in the Sn(II) compound to the weight of the silver nanowire (B) needs to be carefully optimized to obtain the best antioxidant protection. 3.3 Exposure to H ₂ S

The products (7), (8) and (9) and the comparative product according to the present invention were exposed to an atmosphere composed of H ₂ S and N ₂ (each 50% by volume) at room temperature for 10 hours. In each product, the transparent conductive film is arranged on the surface of the glass substrate, as described in Section 2 above.

On prior exposure to H ₂ S, after exposure to H ₂ S 5 hours and after exposure to H ₂ S 10 hours at a temperature 25 ℃ a pressure of 101.3 kPa and the means disposed on the substrate surface placed in The four-point probe on the plurality of metallic nano-objects (B) is used to measure the sheet resistance of the transparent conductive film.

The products (7), (8) and (9) are used by adding 2 (0.3 μl, 0.5 μl and 1 μl respectively) of different amounts in step (2) of the method of manufacturing ink (see section 1.2 above) -Obtained from an ink made of tin (II) ethylhexanoate, and these products (7), (8) and (9) and comparative products are exposed to H ₂ S as described above. In the products (7), (8) and (9), the thickness of the layer containing tin (II) 2-ethylhexanoate on the surface of the silver nanowire (B) follows the steps of the method of manufacturing ink ( 2) During the period (see section 1.2 above), the amount of tin (II) 2-ethylhexanoate added increases gradually.

Before exposure to H ₂ S, the sheet resistance of the comparative product (see FIG. 8) is lower than the sheet resistance of the product according to the present invention because the silver nanowire in the comparative product is not coated with a layer containing Sn(II) compound . However, for the comparative article, a significant increase in sheet resistance after exposure to H ₂ S was observed. In contrast, for products (7) and (8), even after 10 hours of exposure to H ₂ S, the sheet resistance did not exceed 150 ohms/square. Because the weight of tin (II) 2-ethylhexanoate added in step (2) of the method of manufacturing ink (see section 1.2 above) is higher than the weight of the silver nanowire (B0) in the precursor composition Therefore, before exposure to H ₂ S, the product (9) has shown a higher sheet resistance. Obviously, in the product (9), the coating on the surface of the silver nanowire produced by tin (II) 2-ethylhexanoate is quite thick, so the sheet resistance of the transparent conductive film obtained using this ink is quite high. The product (9) showed a significant increase in sheet resistance after being exposed to H ₂ S, but it was smaller than the comparative product.

no

The figures show: Figure 1a-d SEM, TEM and HRTEM images of the product according to the invention Figure 2a, b The Raman spectrum of the product according to the invention and the comparative product and the XPS diagram of the product according to the invention Figure 3a-f SEM images of products according to the present invention and comparative products before and after annealing Figure 4a, b XRD patterns of products according to the present invention and comparative products before and after annealing Figure 5a Before and after annealing at 100°C according to one of the present invention Sheet resistance and light transmittance of series of products Figure 5b Sheet resistance of products according to the invention and comparative products as a function of time during dynamic heating Figure 6a-f Products and comparison products according to the invention before and after oxidation treatment XPS diagram of Figure 7 Sheet resistance of the product according to the present invention and the comparative product before and after the oxidation treatment Figure 8 Sheet resistance of the product according to the present invention and the comparative product before and after exposure to H ₂ S

Claims (15)

A composition comprising (A) a carrier liquid selected from a non-aqueous polar liquid (B) metal nano-objects dispersed in the carrier liquid (A), wherein the surfaces of the dispersed metal nano-objects (B) At least partially coated with a layer containing one or more Sn(II) compounds wherein the Sn(II) compounds are selected from Sn(II) soluble in the same carrier liquid (A) in which no metallic nano-objects are dispersed ) The compound limitation is that the layer does not contain any one of SnCl ₂ , SnBr ₂ and SnI ₂ wherein the weight fraction of the metal nano-objects (B) in the composition is in the range of 0.001% to 10% by weight and The ratio of the total weight of Sn(II) in the Sn(II) compounds to the weight of the metal nano-objects is in the range of 0.01% to 3.9%. The composition according to claim 1, wherein the Sn(II) compounds are selected from the group consisting of tin(II) 2-ethylhexanoate, SnF ₂ , tin(II) acetone and tin(II) methanesulfonate The group and/or the metal nano-objects are selected from the group consisting of metal nano-sheets and metal nano-wires, preferably selected from the group consisting of silver nano-wires and copper nano-wires and/or the carrier liquid (A ) Is selected from alcohols having 1 to 5 carbon atoms, preferably ethanol. The composition according to claim 1 or 2, wherein in the composition Based on the total weight of the composition, the weight fraction of the metal nano-objects (B) is in the range of 0.001 to 5% by weight, preferably 0.002 to 1% by weight And/or The ratio of the total weight of Sn(II) in the Sn(II) compounds to the weight of the metal nano-objects is in the range of 2.0% to 2.5%. The composition according to any one of the preceding claims, further comprising (C) Binder, selected from the group consisting of cellulose ether, crystalline cellulose, poly(meth)acrylate, copolymer of acrylate and methacrylate, styrene and (meth)acrylate Copolymers, polystyrene, polyacrylamide, polyvinyl alcohol, polyvinylpyrrolidone, polystyrenesulfonic acid, polyester, polyurethane, polycarbonate, gelatin, acrylate-vinyl acetate copolymer, poly Glucose and its blends. A method for preparing the composition according to any one of claims 1 to 4, the method comprising the following step (1) providing a precursor composition, the precursor composition comprising (A) selected from non-aqueous polar Liquid carrier liquid (B0) metal nano-objects dispersed in the carrier liquid (A) (2) Add one or more Sn(II) compounds to the precursor composition, the one or more Sn(II) compounds Soluble in the same carrier liquid (A) in which metal nano-objects are not dispersed, the restriction is that the one or more Sn(II) compounds do not contain any of SnCl ₂ , SnBr ₂ and SnI ₂ , in the step (2), the amount of the Sn(II) compounds added is such that the total weight of Sn(II) in the Sn(II) compounds added is relative to the metal nano-objects (B0) in the precursor composition The weight ratio is in the range of 0.01% to 3.9%. The method according to claim 5, wherein In the precursor solution provided in step (1), based on the total weight of the precursor composition, the weight fraction of the metal nano-objects (B0) is in the range of 0.001% to 10% by weight, preferably 0.001 to 5% by weight, preferably 0.002% to 1% by weight And/or In step (2), the amount of the Sn(II) compounds added is such that the total weight of Sn(II) in the Sn(II) compounds added is relative to the metal nano-objects in the precursor composition ( B0) The weight ratio is in the range of 2.0% to 2.5%. The method according to claim 5 or 6, wherein the Sn(II) compound is selected from the group consisting of tin(II) 2-ethylhexanoate, SnF ₂ , tin(II) acetone, and tin(II) methanesulfonate Group. A method for preparing an article, comprising a substrate having a surface and a plurality of (B) metal nano-objects arranged on the surface of the substrate, wherein the surfaces of the metal nano-objects are at least partially coated with A layer of one or more Sn(II) compounds, with the restriction that the layer does not contain any one of SnCl ₂ , SnBr ₂ and SnI ₂ , the method includes the following steps by applying any one of claims 1 to 4 The composition described above is applied to the surface of the substrate or the surface of the temporary support to form a wet film, and the carrier liquid (A) that removes the composition from the wet film formed on the surface of the substrate or the surface of the temporary support will be as The solid component of the composition according to any one of claims 1 to 4 is left on the surface of the substrate or the solid component of the composition according to any one of claims 1 to 4 is removed from the temporary support The surface is transferred to the substrate surface. The method according to claim 8, wherein the temporary support is a filter membrane, and the method includes the following steps: By applying the composition as described in any one of claims 1 to 4 to the surface of the filter membrane, thereby forming a wet film on the surface of the filter membrane, The carrier liquid (A) of the composition is removed from the wet membrane formed on the surface of the filtration membrane by filtration, so that a filtration residue including the metal nano-objects (B) is formed on the surface of the filtration membrane Thing The filtering residue is transferred to the surface of the substrate, so that the metallic nano-objects (B) are placed on the surface of the substrate. The method according to claim 8, which comprises the following steps Forming a wet film on the surface of the substrate by applying the composition as described in any one of claims 1 to 4 to the surface of the substrate The carrier liquid (A) is removed from the wet film formed on the surface of the substrate by evaporation. The method of any one of claims 8 to 10, wherein the substrate comprises one or more materials selected from the group consisting of glass and organic polymers. The method according to any one of claims 8 to 11, further comprising the steps of: at a temperature in the range of 140°C to 200°C, preferably in the range of 140°C to 160°C, under an air atmosphere , The metal nano-objects (B) are annealed on the surface of the substrate for a duration of 10 minutes to 60 minutes, preferably 20 minutes to 40 minutes. Use of a Sn(II) compound for preparing the composition according to any one of claims 1 to 4. The use according to claim 13, wherein the Sn(II) compounds are selected from the group consisting of tin(II) 2-ethylhexanoate, SnF ₂ , tin(II) acetone, and tin(II) methanesulfonate. A use of the ink according to any one of claims 1 to 4 for obtaining a conductive transparent film containing a metal nano-object (B) arranged on the surface of a substrate.

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