JP2014044839A - Transparent electrode, method for producing conductive transparent thin film, and conductive transparent thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent electrode having a low sheet resistance and high transmittance.SOLUTION: A transparent electrode 101 includes an insulating substrate 121 that transmits light and a conducting layer 141 disposed on the substrate 121. The conducting layer 141 has a plurality of ridges 161 to reduce a sheet resistance. Each of the plurality of ridges 161 has a width that is not visually recognizable. The transmittance for light in the plurality of the ridges is a predetermined opaque threshold or lower. The transmittance for light in a transmissive region 162 among the plurality of ridges 161 is a predetermined transparent threshold or higher.

Description

  The present invention relates to a transparent electrode, a method for producing a conductive transparent thin film, and a conductive transparent thin film.

  Conventionally, a transparent electrode using a conductive transparent thin film made of carbon nanotubes or the like has been proposed.

  In many transparent electrodes, the thickness of the conductive thin film is set so that the transmittance is 80% to 95%, and non-conductive transparent or translucent (transparent or translucent) such as glass or plastic is used. By placing it on a translucent substrate, conductivity and transmittance are achieved.

  For example, Patent Document 1 discloses a transparent electrode in which a network thin film of carbon nanotubes is directly formed on a transparent substrate.

  In this technique, first, a thin film in which carbon nanotubes and granular materials are mixed is formed on a substrate. Then, a carbon nanotube will be located between granular materials. Thereafter, when the particulate matter is removed, a large number of voids are generated. In this technique, a network structure of carbon nanotubes having three-dimensional voids is formed, and the transparency is determined by the void ratio and the density of the carbon nanotubes.

  On the other hand, Non-Patent Document 1 proposes a technique of forming an electronic circuit pattern with carbon nanotubes for use as wiring.

  In this technique, first, a mask (resist) for forming a circuit pattern is arranged on a membrane filter. Then, the gas containing carbon nanotubes is filtered through the mask pattern and the membrane filter. Then, a thin film made of carbon nanotubes is formed on the membrane filter. Thereafter, the electronic circuit is formed by removing the mask and then transferring the thin film to the substrate.

  In general, if the surface density of the carbon nanotube is low, the light transmittance is high, but the sheet resistance is high. Further, the level of sheet resistance depends on the type of carbon nanotube.

  The carbon nanotube network thin film disclosed in Patent Document 1 has a surface resistance of 1100 Ω / sq. To 6100 Ω / sq.

JP 2008-177165 A

Chaehyun Lim, Dong-Hun Min and Seung-Beck Lee, Direct patterning of carbon nanotube network devices by selective vacuum filtration, Applied Physics Lettes, Vol.91, No.243117, American Institute of Pysics 2007

  However, a conductive transparent thin film capable of reducing sheet resistance while maintaining high light transmittance and a transparent electrode using the same are strongly desired.

  In addition, there is a great demand for a transparent electrode having a structure in which conductors such as carbon nanotubes are tightly coupled, instead of a network structure having a three-dimensional void having a problem in strength.

  This invention solves the above subjects, and it aims at providing the manufacturing method of a transparent electrode, a conductive transparent thin film, and a conductive transparent thin film.

The transparent electrode according to the first aspect of the present invention is:
An insulating base material that transmits light;
A conductive layer disposed on the substrate;
With
The conductive layer has a plurality of wrinkles for reducing sheet resistance,
The width of each of the plurality of wrinkles is a width that cannot be visually recognized,
The reflectance of the light in the plurality of eyelids is a predetermined darkness threshold value or less,
The light transmittance in the plurality of ridges is below a predetermined opacity threshold,
The light transmittance in the transmissive region between the plurality of ridges is configured to be equal to or greater than a predetermined transparency threshold.

In the transparent electrode of the present invention,
The plurality of ridges can be configured to form a lattice.

In the transparent electrode of the present invention,
The conductive layer can be formed of carbon nanotubes.

In the transparent electrode of the present invention,
The predetermined opacity threshold is a constant of 50 percent or less;
The predetermined transparency threshold is a constant of 80% or more,
The plurality of wrinkles cover 1% to 20% of the conductive layer;
Each of the plurality of ridges has a width of 0.1 μm to 10 μm,
The areal density of the carbon nanotubes in the plurality of ridges is 10 μg / cm ^{2 to} 500 μg / cm ² ,
The areal density of the carbon nanotubes in the transmission region can be configured to be 0.1 μg / cm ^{2 to} 2 μg / cm ² or less.

In the transparent electrode of the present invention,
The conductive layer has a first layer made of a first conductor in contact with the base material, and a second layer made of a second conductor disposed on the first layer,
By arranging the second layer on the first layer, the plurality of wrinkles can be formed.

In the transparent electrode of the present invention,
Either one or both of the first conductor and the second conductor can be formed of carbon nanotubes.

The method for producing a conductive transparent thin film according to the second aspect of the present invention comprises:
Forming a transmissive layer comprising a transmissive conductor uniformly spreading on the support material; and
Forming an opaque layer made of an opaque conductor having a pattern on the transparent layer;
With
The light transmittance in the transmissive layer is equal to or greater than a predetermined transparency threshold,
The light transmission in the opaque layer is less than or equal to a predetermined opacity threshold;
The width of the pattern is configured such that it cannot be recognized visually.

The method for producing a conductive transparent thin film according to the third aspect of the present invention comprises:
Forming an impermeable layer made of an impermeable conductor having a pattern on a support material;
Forming a transmissive layer made of a transmissive conductor that spreads uniformly on the support material and the impermeable layer;
With
The light transmittance in the transmissive layer is equal to or greater than a predetermined transparency threshold,
The light transmission in the opaque layer is less than or equal to a predetermined opacity threshold;
The width of the pattern is configured such that it cannot be recognized visually.

In the method for producing a conductive transparent thin film of the present invention,
Either one or both of the transmissive layer and the non-permeable layer can be configured to be a layer composed of carbon nanotubes.

In the method for producing a conductive transparent thin film of the present invention,
The transmission layer and the non-transmission layer are layers composed of carbon nanotubes, respectively.
The pattern has a width of 0.1 μm to 10 μm,
The areal density of the carbon nanotubes in the impermeable layer is 10 μg / cm ^{2 to} 500 μg / cm ² ,
The surface density of the carbon nanotubes in the transmissive layer can be configured to be 0.1 μg / cm ^{2 to} 2 μg / cm ² or less.

In the method for producing a conductive transparent thin film of the present invention,
The support material is a filter;
The permeable layer and the impermeable layer are both thin films obtained by filtering an aerosol of carbon nanotubes or a dispersion of carbon nanotubes with the filter,
After the transmissive layer and the non-transmissive layer are formed on the filter, the method further includes the step of transferring the transmissive layer and the non-transmissive layer onto an insulating base material that transmits light. Can be configured.

In the method for producing a conductive transparent thin film of the present invention,
An organic film or inorganic film mask for forming the pattern can be arranged on the front or back surface of the filter.

In the method for producing a conductive transparent thin film of the present invention,
The support material is an insulating base material that transmits light,
By filtering the aerosol of carbon nanotubes or the dispersion of carbon nanotubes with a filter, the thin film for the transmission layer and the thin film for the non-transmission layer are formed, and the thin film for the transmission layer After transferring one of the thin film for the impermeable layer onto the substrate, the other of the thin film for the transparent layer and the thin film for the impermeable layer is transferred onto the substrate. It is possible to further comprise a step of transferring to.

The conductive transparent thin film according to the fourth aspect of the present invention is
A support material;
A conductive layer disposed on the support;
With
The conductive layer has a plurality of wrinkles,
The light transmittance in the plurality of ridges is below a predetermined opacity threshold,
The light transmittance in the transmission region between the plurality of ridges is equal to or greater than a predetermined transparency threshold;
The predetermined opacity threshold is a constant of 50 percent or less;
The predetermined transparency threshold is a constant of 80% or more,
The plurality of ridges are configured to cover 1% to 20% of the conductive layer.

  According to the present invention, a transparent electrode, a method for producing a conductive transparent thin film, and a conductive transparent thin film can be provided.

It is a top view of the transparent electrode which concerns on this embodiment. It is sectional drawing of the transparent electrode which concerns on this embodiment. It is a graph which shows the relationship between the sheet resistance and the transmittance | permeability of the experimental example of the transparent electrode of this embodiment, and the transparent electrode of a prior art. It is sectional drawing explaining the method of performing filtration by a filter, without using a mask. It is sectional drawing explaining the method of arrange | positioning a mask in an upstream and filtering with a filter. It is sectional drawing explaining the method of arrange | positioning a mask downstream and filtering with a filter. It is sectional drawing explaining the example of the procedure which transcribe | transfers the whole film | membrane and a pattern film | membrane to a base material. It is sectional drawing explaining the example of the procedure which transcribe | transfers the whole film | membrane and a pattern film | membrane to a base material. It is sectional drawing explaining the example of the procedure which transcribe | transfers the whole film | membrane and a pattern film | membrane to a base material. It is sectional drawing explaining the example of the procedure which transcribe | transfers the whole film | membrane and a pattern film | membrane to a base material. It is sectional drawing explaining the example of the procedure which transcribe | transfers the whole film | membrane and a pattern film | membrane to a base material. It is sectional drawing explaining the example of the procedure which transcribe | transfers the whole film | membrane and a pattern film | membrane to a base material. It is sectional drawing which shows a mode that it filtered until the conductive material of sufficient thickness as a whole film | membrane was accumulate | stored in places other than the opening part of a mask after a pattern film | membrane was formed. It is sectional drawing which shows a mode that it filtered until the conductive material of sufficient thickness as a whole film | membrane was accumulate | stored in places other than the opening part of a mask after a pattern film | membrane was formed. It is sectional drawing which shows the mode of the procedure of transcription | transfer using affinity. It is sectional drawing which shows the mode of the procedure of transcription | transfer using affinity. It is sectional drawing which shows the mode of the procedure of transcription | transfer using affinity. It is sectional drawing which shows the mode of the procedure of transcription | transfer using affinity. It is sectional drawing which shows the mode of the procedure of transcription | transfer using affinity. It is sectional drawing which shows the mode of the procedure of transcription | transfer using affinity. It is sectional drawing which shows the mode of the procedure of transcription | transfer using affinity.

  Embodiments of the present invention will be described below. The embodiments described below are for explanation, and do not limit the scope of the present invention. Therefore, those skilled in the art can employ embodiments in which each or all of these elements are replaced with equivalent ones, and these embodiments are also included in the scope of the present invention.

  FIG. 1 is a plan view of a transparent electrode according to this embodiment, and FIG. 2 is a cross-sectional view of the transparent electrode according to this embodiment. Hereinafter, a description will be given with reference to FIG. In these drawings and the subsequent drawings, the dimensions of each part are exaggerated for easy understanding.

  In the transparent electrode 101 shown in these drawings, a conductive layer 141 is disposed on a base material 121 that transmits insulating light.

  As the base material 121, a substrate formed of a transparent or translucent material, for example, a glass substrate, a quartz substrate, a flexible transparent substrate formed of plastic, or the like can be used.

  Examples of the material for the flexible transparent substrate include acrylic resin, olefin maleimide copolymer, norbornene resin, polyimide (PI), polyetherimide, polyetheretherketone, polyethersulfone, polyester (PE), polyethylene terephthalate (PET) ), Polyethylene naphthalate (PEN), polycarbonate, polystyrene, polypropylene (PP), polytetrafluoroethylene (PTFE), or combinations thereof.

  The material of the conductive layer 141 is typically a carbon nanotube, but it is also possible to use, for example, a gold nanorod, a fiber such as zinc oxide or gallium nitride, or a fine wire.

  Hereinafter, in order to facilitate understanding, the conductive layer 141 will be described by classifying the conductive layer 141 into two parts, that is, a first layer 151 and a second layer 152 when viewed from the cross section.

  The first layer 151 is a thin film that is in contact with the substrate 121 so as to spread, and the thickness thereof is a transmissive layer that is thin enough to transmit light sufficiently.

  The second layer 152 is an impermeable layer that forms a grid extending on the surface of the first layer 151, and refers only to a line portion of the grid. The thickness of the second layer 152 may be thick enough not to transmit light, but the width of the grid lines needs to be narrow enough to be invisible to the human eye. Typically, if the width of the grid line is configured to be equal to or wider than the thickness of the grid line (thickness of the second layer 152), the strength of the second layer 152 can be increased.

  The second layer 152 is preferably made of a dark material having a sufficiently low light reflectance. Even if the width of the grid lines of the second layer 152 is a width that cannot be visually recognized, the grid lines may reflect light if the width of the grid lines is equal to or greater than the visible light wavelength. Therefore, when a highly reflective metal or the like is used as the material of the second layer 152, the presence of the second layer 152 may be known due to reflection on the surface of the transparent electrode.

  However, depending on the application of the transparent electrode 101, it is possible to relax the above-mentioned conditions in the width and material of the second layer 152. For example, when the transparent electrode 101 is applied to a solar cell, there is no problem even if the second layer 152 can be recognized by human vision. Therefore, it is possible to increase the width of the grid lines of the second layer, or to use a metal or a metal compound as the material.

  On the other hand, the conductive layer 141 has ridges 161 that are thick enough not to transmit light when viewed from above, and a transmissive region that is surrounded by the ridges and thin enough to transmit light sufficiently. 162.

  In the present embodiment, the upper limit value of the light transmittance in the ridge 161 is referred to as an opacity threshold, the lower limit value of the light transmittance in the transmissive region 162 is referred to as a transparency threshold, and the reflectance of the light in the ridge 161 is The upper limit is called a darkness threshold.

  In general, the opacity threshold is a constant of 50% or less, the transparency threshold is a constant of 80% or more, and the darkness threshold is a constant of 10% or less, but the value is appropriately determined according to the application. It is done.

  Now, the ridge 161 corresponds to the second layer 152, and in the example shown in this figure, a grid is formed by crossing each other so that the ridges form a plurality of square sides. The grid line of the grid corresponds to 畝 161. Although the light transmittance of the grid lines is low and opaque, the width of the ridges 161 forming the grid is sufficiently thin so that it cannot be perceived by human eyes.

  In addition, the transmissive region 162 is a substantially square-shaped region that is exposed without being hidden by the second layer 152 in the first layer 151.

  The thickness of the transmission region 162 is the thickness of the first layer 151, and the thickness of the ridge 161 is the sum of the thickness of the first layer 151 and the thickness of the second layer 152. When the second layer 152 is formed of the same material and the same surface density, the surface density of the conductor in the ridge 161 is higher than the surface density of the conductor in the transmissive region 162.

  Therefore, the surface density of the conductor of the entire conductive layer 141 is naturally higher than the surface density of the conductor of the first layer 151.

  It can be considered that the conventional transparent electrode is arranged on the substrate 121 by adopting only the first layer 151 as the conductive layer 141 in this embodiment.

  Therefore, the transparent electrode 101 according to the present embodiment has a higher surface density of the conductor, that is, a lower sheet resistance than the conventional transparent electrode by the amount of the second layer 152.

  In order to reduce the sheet resistance, the thickness and width of the second layer 152 may be increased, or the coverage of the surface of the conductive layer 141 by the second layer 152 may be increased. However, since the second layer 152 has low light transmittance, if the thickness or width is too large, the second layer 152 becomes visible to the human eye. If the coverage is too high, the light transmittance of the entire transparent electrode 101 is lowered.

  Therefore, in this embodiment, the width of the grid line of the second layer 152, that is, the width of the flange 161 of the conductive layer 141 and the thickness of the second layer 152 (the thickness of the grid line of the second layer 152) are The width and thickness are invisible to the human eye. For example, the width of the flange 161 of the conductive layer 141 and the thickness of the second layer 152 are 10 μm or less.

  The resolution of human vision cannot be obtained below 10 μm. For this reason, even if a human observes the conductive layer 141, it is considered that the presence of the grid of the second layer 152 and the ridge 161 cannot be known. In particular, carbon nanotubes are extremely dark materials that are conductive and can be processed into fine wires, but also can have a light reflectance of several percent or less. Therefore, when carbon nanotubes are used as the material of the second layer 152, it is difficult for humans to directly recognize the grid and ridge 161 of the second layer 152 with the naked eye.

  The coverage of the second layer 152 may be determined according to the use of the transparent electrode 101, but is typically about 1 to 20 percent.

  Hereinafter, a simple calculation example will be described.

First, consider a case where the transparent electrode 101 having a light transmittance of 90% is formed from only the first layer 151 by using a conventional technique. As an example of the carbon nanotubes in this case, the thickness of the first layer 151 is 20 nm, and the amount of carbon nanotubes per unit area is 10 mg / m ² = 1 μg / cm ² .

  In the present invention, the opaque ridge 161 does not transmit light, whereas the transmissive region 162 transmits light. Therefore, the overall transmittance of the transparent electrode 101 is determined by the coverage of the surface of the conductive layer 141 by the ridges 161.

  For example, if the light transmittance in the transmissive region 162 is 95% and the coverage of the second layer 152 covering the first layer 151 is 5%, both are subtracted, and the light transmission rate is the same as in the conventional example. A transparent electrode 101 that achieves a transmittance of 90 percent can be created.

The light transmittance is considered to decrease exponentially with respect to the thickness and the amount of carbon nanotubes per unit area. Since 0.95 ² ≈0.90, the thickness at which the light transmittance is 95 percent is almost half of the thickness at which the light transmittance is 90 percent.

That is, if the thickness of the first layer 151 is 10 nm and the amount of carbon nanotubes per unit area is 5 mg / m ² = 0.5 μg / cm ² , a light transmittance of 95 percent can be realized.

  On the other hand, since the coverage of the second layer 152 is 5%, if the width and height of the grid lines of the second layer 152 (thickness of the second layer 152) are determined, the length of one side of each square forming the grid is determined. That is, the grid line spacing is determined.

  Here, as shown in FIG. 2, a cross section perpendicular to the longitudinal direction of the sides of the grid is considered. Since the grid lines are arranged orthogonally, a coverage of 5% means that the period between a grid line and the grid line adjacent to it is 40 times the grid line width (2 times the reciprocal of 5 percent). is there.

For example, if the width and height of the grid lines are 1 μm, the period between the grid lines is 40 μm. Further, since the coverage is 5%, the average thickness of the second layer 152 is 1 μm × 5/100 = 0.05 μm = 50 nm. Therefore, if the thickness of the first layer 151 is added to 10 nm, the conductive layer 141 in this calculation example has the same amount of carbon nanotubes as unity 30 nm thick carbon nanotube thin film having a thickness of 50 nm + 10 nm = 60 nm. / m ² = 3 μg / cm ² .

  The sheet resistance value can be approximated as being inversely proportional to the amount of carbon nanotubes per unit area. Therefore, in the transparent electrode 101 of this calculation example, the sheet resistance value can be reduced to one third with the same light transmittance as in the conventional case.

In addition, if the width and height of the grid lines are 10 μm, the period between the grid lines is 400 μm, and the average thickness of the second layer 152 is 10 μm × 5/100 = 0.5 μm = 500 nm. In this case, the conductive layer 141 has a carbon nanotube amount of 255 mg / m ² = 25 μg / cm ² per unit area as much as a uniform carbon nanotube thin film having a thickness of 500 nm + 10 nm = 510 nm. In this calculation example, the sheet resistance value is reduced to 1/25 of the conventional value.

  In the above calculation example, the sheet resistance value in the longitudinal direction of the grid line is calculated. In other cross sections, since the cross sectional area of the conductive layer 141 is larger than that in the above calculation example, the actual sheet resistance value of the transparent electrode 101 exhibits a lower value depending on the direction.

  As described above, in this embodiment, by providing the conductive layer 141 with the ridge 161 having a width and thickness that cannot be understood by humans, the amount of the conductor per unit area is increased, and the sheet resistance is dramatically decreased. be able to. Further, by making the transmission region 162 surrounded by the ridge 161 sufficiently thin and appropriately adjusting the covering area ratio of the ridge 161, the desired transparency can be realized as the entire transparent electrode 101.

  FIG. 3 is a graph showing the relationship between the sheet resistance and the transmittance of the experimental example of the transparent electrode 101 of the present embodiment and the transparent electrode of the prior art. Hereinafter, a description will be given with reference to FIG.

  What is marked as “film” in the figure is a plot representing the characteristics of the transparent electrode according to the prior art, and what is marked as “film + grid” is manufactured according to this embodiment. 6 is a plot showing experimental example characteristics of the transparent electrode 101. The horizontal axis (Sheet Resistance (Ω / sq.)) Of the graph is the sheet resistance, and the vertical axis (Transmittance (%)) is the light transmittance.

Theoretically, the relationship between the light transmittance T and the sheet resistance Rs is expressed by using a certain constant K,
T = exp (-1 / (K × Rs))
It can be seen that the sheet resistance according to the prior art film conforms to this.

  Hereinafter, the specifications of the transparent electrode 101 expressed by film + grid and the manufacturing process will be briefly described.

  The conductive layer 141 of the transparent electrode 101 expressed by film + grid is formed of carbon nanotubes.

  First, carbon nanotubes themselves were grown by chemical vapor deposition. Thereafter, the carbon nanotubes were filtered by a filter, and then transferred to a polyethylene naphthalate base material 121 to form a first layer 151.

  Furthermore, after forming a grid-like mask pattern on the filter using a photoresist, the carbon nanotubes were collected and transferred onto the first layer 151 to form the second layer 152.

  And after performing the densification process by 2-propanol (IPA) and doping using nitric acid, the light transmittance was measured and the sheet resistance was evaluated by a four-terminal measurement method.

  The grid period of the second layer 152 is 37.5 μm, and the width of the grid line is 3 μm. In addition, measurement and evaluation are performed by changing the surface density of the carbon nanotubes in the second layer 152 in various ways.

  As shown in this figure, it can be seen that the transparent electrode 101 (film + grid) according to the present embodiment has a much lower sheet resistance than the conventional transparent electrode (film) even if it has the same transmittance.

  For example, when the light transmittance is 80%, the conventional transparent electrode (film) has a sheet resistance of 95 Ω / sq., Whereas the transparent electrode 101 (film + grid) according to the present embodiment is It turns out that it has fallen to 53 ohm / sq.

  The length of each carbon nanotube fiber currently used as a material is about 10 μm. If the width of the grid line of the second layer is narrower than this, for example, about 0.1 μm to 5 μm, it is considered that the fiber directions can be aligned.

  That is, by making the width of the grid line shorter than the length of the carbon nanotube alone, the direction of the fibers can be aligned, the electrical conductivity can be further improved, and the sheet resistance can be reduced.

  In addition, in the cross section shown in FIG. 2, the cross-sectional shape of the flange 161 is substantially square, but can be any shape such as a rectangle, a trapezoid, a triangle, and a semicircle. That is, the flange 161 has a cross-sectional area sufficient to achieve a desired sheet resistance, and the width and height (thickness) are substantially the same or the height (thickness) is greater than the width in order to maintain strength. Any small shape can be used.

  Note that when densification or doping is performed, the cross-sectional shape of the ridge 161 changes, but the width of the ridge 161 and the surface density of the conductor hardly change.

  Further, in the densification treatment, light scattering is suppressed, and when doping is performed, electrons in the valence band are reduced, so that light in a band including visible light cannot be absorbed. For this reason, the light transmittance is slightly improved.

  That is, in order to achieve the effect according to the present embodiment, a transmissive region 162 having a high light transmittance and a ridge 161 having a low light transmittance are prepared to achieve a desired transmittance and sheet resistance value. In addition, the covering ratio of the ridges 161, the surface density of the conductors in the ridges 161 and the transmission region 162 may be designed.

  Below, the manufacturing method of the transparent electrode 101 which concerns on this embodiment, and the manufacturing method of an electroconductive transparent thin film are demonstrated in detail.

  Note that only the conductive layer 141 disposed on the base 121 or only the conductive layer 141 before being disposed on the base 121 is referred to as a conductive transparent thin film.

  When a conductive transparent thin film is manufactured independently of the base material 121, the transparent electrode 101 is made by arranging the conductive transparent thin film on the base material 121. On the other hand, it is also possible to manufacture a conductive transparent thin film on the base material 121.

  Hereinafter, a method of manufacturing the transparent electrode 101 in which the conductive layer 141 made of a conductive transparent thin film is supported by the base material 121 by filtration using a filter will be described.

  As disclosed in Patent Document 1, a technique for forming a thin film by filtration using a filter from carbon nanotubes or the like is widely known.

  In this technique, a dispersion medium such as an aerosol (vapor phase dispersion) or a colloid solution (liquid phase dispersion) containing a conductive material such as carbon nanotube is prepared, and this is filtered through a membrane filter. Then, conductive materials are integrated on the supply side (upstream side) of the filter to form a thin film. If the thin film formed here is transferred to a transparent substrate, a transparent electrode based on the prior art can be produced.

  However, in this embodiment, it is necessary to form the ridge 161 and the transmissive region 162 having different surface densities of the conductive material in the conductive layer 141. Therefore, a mask for extracting the shape of the ridge 161 is used during filtration using a filter.

  In this case, there are a technique in which a metal foil having slits is brought into close contact with the filter and used as a mask, and a technique in which a resist pattern of an organic film or an inorganic film is attached in advance to the filter itself.

  Further, there are a method of arranging a mask with respect to the filter on the upstream side of the supply of the dispersion medium and a method of arranging the mask on the downstream side.

  For example, the technique disclosed in Non-Patent Document 1 corresponds to a technique in which a resist pattern is attached to the upstream side of a filter to form a mask.

  FIG. 4A is a cross-sectional view illustrating a technique for performing filtration using a filter without using a mask. FIG. 4B is a cross-sectional view illustrating a method of performing filtration using a filter with a mask disposed on the upstream side. FIG. 4C is a cross-sectional view illustrating a method of performing filtration using a filter with a mask disposed on the downstream side.

  As shown in these drawings, a dispersion medium such as an aerosol or a colloid solution containing a conductive material such as a carbon nanotube is passed from the upstream side to the downstream side of the filter 401 for filtration.

  As shown in FIG. 4A, when the mask 402 is not used, the dispersion medium passes through the entire surface of the filter 401 and passes from the upstream side to the downstream side, so that the conductive material covers the entire upstream side of the filter 401. The material is accumulated and the entire film 404 is formed.

  As shown in FIGS. 4B and 4C, when the mask 402 is installed on the upstream side or downstream side of the filter 401, the dispersion medium passes through the opening 403 of the mask 402 and passes from upstream to downstream. Therefore, the conductive material is accumulated in the vicinity of the opening 403 of the filter 401, and the pattern film 405 is formed. Therefore, if the openings 403 are prepared in a desired shape such as a grid, the pattern film 405 for forming the ridges 161 can be formed.

  When the entire film 404 and the pattern film 405 formed in this manner are transferred from the filter 401 onto the substrate 121, the conductive layer 141 can be formed on the substrate 121.

  An example of a procedure for manufacturing the filter 401 provided with the mask 402 will be described below.

  First, a membrane filter or the like is prepared as the filter 401, and the surface thereof is coated with fluorine. Thereafter, a photoresist is dropped and spin coated. Further, development is performed after exposure of the pattern by photolithography, whereby a part of the photoresist is removed, and the remainder of the photoresist is used as the mask 402.

  In this method, the hydrophobicity is increased by fluorine coating to prevent the photoresist from penetrating the membrane filter, and the dripped photoresist is uniformly spread over the entire surface of the filter by rotating the membrane filter. Therefore, it is possible to easily manufacture the mask 402 installed on the filter 401 and to make the pattern of the mask 402 fine.

  5A, 5B, and 5C are cross-sectional views illustrating an example of a procedure for transferring the entire film 404 and the pattern film 405 to the substrate 121. FIG. This will be described below with reference to these drawings.

  In the first procedure, first, as shown in FIG. 5A, the filter 401 that supports the entire film 404 is brought close to and in close contact with the base material 121. Then, as shown in FIG. 5B, the entire film 404 is transferred to the base material 121.

  Next, as shown in FIG. 5B, the filter 401 that supports the pattern film 405 is brought into close contact with the substrate 121. Then, as shown in FIG. 5C, the pattern film 405 is transferred onto the entire film 404 of the substrate 121.

  As a result, the conductive film 141 having the flange 161 and the transmission region 162 is formed on the base material 121 by the entire film 404 and the pattern film 405, and the transmission electrode 101 is completed. Thereafter, as described above, a densification process or doping may be performed. The same applies to each method and embodiment described below.

  5D, 5E, and 5F are cross-sectional views illustrating an example of a procedure for transferring the entire film 404 and the pattern film 405 to the substrate 121. FIG. This will be described below with reference to these drawings.

  In the second procedure, first, as shown in FIG. 5D, the filter 401 that supports the pattern film 405 is brought close to and in close contact with the substrate 121. Then, as shown in FIG. 5E, the pattern film 405 is transferred from the filter 401 to the base material 121.

  Next, as shown in FIG. 5E, the filter 401 that supports the entire film 404 is brought into close contact with the base material 121. Then, as shown in FIG. 5F, the entire film 404 is transferred so as to cover the substrate 121 and the pattern film 405.

  As a result, as shown in FIG. 5F, the entire layer 404 and the pattern layer 405 form a conductive layer 141 having a ridge 161 and a transmissive region 162 on the substrate 121, and the transparent electrode 101 is completed.

  In these explanatory diagrams, the pattern film 405 is formed in a manner in which the mask 402 is arranged on the downstream side of the supply of the dispersion medium, and the pattern film 405 and the mask 402 are connected to the filter 401. It is arranged so that Therefore, it is not necessary to remove the mask 402 at the time of transfer. However, when filtration is performed with a metal foil as a mask 402 in close contact with the filter 401, the mask 402 may be removed before transfer.

  On the other hand, when the mask 402 is arranged on the upstream side of the supply of the dispersion medium, as disclosed in Non-Patent Document 1, transfer can be performed after the mask 402 is removed from the filter 401. .

  However, when the conductive film is accumulated to a degree slightly overflowing from the mask 402 to form the pattern film 405, or when the filter 401 is brought into close contact with the base material 121 via the mask 402, the elasticity of the base material 121 or the mask 402 When the pattern film 405 is close to or in contact with the substrate 121, the pattern film 405 may be peeled off from the filter 401. In this case, it is not necessary to remove the mask 402 before transfer.

  In the method of adopting an appropriate organic film or inorganic film as the material of the mask 402 and transferring the pattern film 405 without removing the mask 402 from the filter 401, the filter 401 provided with the mask 402 is reused as it is. Therefore, manufacturing cost can be reduced.

  As described above, the order of the transfer of the entire film 404 and the transfer of the pattern film 405 may be any first and later. By adopting these procedures, the conductive layer 141 that is a conductive transparent thin film is supported by the base material 121 that is a support.

  In the above procedure, the pattern film 405 and the entire film 404 can be manufactured independently or in parallel. Therefore, for example, as the pattern film 405, while using carbon nanotubes as a conductive material, it is possible to form the entire film 404 from another material.

  Here, in order for the pattern film 405 and the entire film 404 to be transferred from the filter 401 to the base material 121, the affinity (interaction) between the conductive material and the filter 401 is determined by the conductive material and the base material 121. It needs to be weaker than the affinity (interaction).

  When carbon nanotubes are used as the conductive material and a polyethylene terephthalate film is used as the base material 121, polytetrafluoroethylene, polyvinylidene fluoride, or the like can be used as the material of the filter 401. .

  In general, as a method for increasing the affinity, it is conceivable to use a material having a large surface energy (surface tension) or to modify the surface by oxygen plasma treatment. Further, a material having a strong interaction with carbon nanotubes such as 3-aminopropyltriethoxysilane (APTES) can be used.

  On the other hand, as a technique for reducing the affinity, it is conceivable to use a material having a low surface energy (surface tension) or to perform a fluorine plasma treatment.

  For example, the surface energy is 44 mN / m for polyimide, polyethylene terephthalate, polyethylene naphthalate, 36 mN / m for polyester, 32 mN / m for polypropylene, 22 mN / m for polytetrafluoroethylene, depending on the material. The value is different.

  Therefore, the affinity (interaction) with the carbon nanotubes on the upstream side of the filter 401 and on the surface of the mask 402 installed on the upstream side is obtained by the above-described method so that the transfer to the base material 121 is appropriately performed. It is desirable to adjust.

  In the above manufacturing procedure, the conductive transparent thin film forming the conductive layer 141 is completed in a state where it is supported by the base material 121 by two times of transfer.

  In the following, by forming the ridge 161 and the transmission region 162 of the conductive layer 141 on the filter 401, a conductive transparent thin film supported by the filter 401 is formed, and then transferred to the substrate 121. A method of replacing the support supporting the conductive transparent thin film from the filter 401 to the base material 121 will be described.

  In this method, as shown in FIGS. 4B and 4C, even after the conductive material is accumulated in the opening 403 of the mask 402 and the pattern film 405 is formed, the conductive film is formed in a place other than the opening 403 of the mask 402. Filtration is further continued until a conductive material having a sufficient thickness as the entire membrane 404 is accumulated.

  In general, the conductive material is accumulated at the opening 403 of the mask 402 at high speed on the flow of the dispersion medium. However, the conductive material dispersed in the dispersion medium is slowly deposited outside the opening 403. Therefore, the pattern film 405 and the entire film 404 can be formed simultaneously by adjusting these speeds.

  FIG. 6A and FIG. 6B show that after the pattern film 405 is formed, filtration is continued until a conductive material having a sufficient thickness as the entire film 404 is accumulated outside the opening 403 of the mask 402. It is sectional drawing which shows a mode that it went. Hereinafter, description will be given with reference to these drawings.

  As shown in these drawings, after the pattern film 405 is formed, if the filtration is continuously performed, the conductive material is also accumulated in places other than the opening 403 of the mask 402. That is, by continuously performing filtration, the entire film 404 is formed so as to cover the pattern film 405.

  Although not explicitly shown in these drawings, the thickness of the entire film 404 tends to increase in the vicinity of the opening 403 of the mask 402 and decrease as it moves away from the opening 403. However, by changing the pressure difference and flow rate between the upstream and downstream after the pattern film 405 is formed, or by selecting the material of the filter 401 in consideration of the affinity for the conductive material, the thickness of the entire layer 404 can be reduced. It is possible to adjust the homogeneity.

  When the entire film 404 is formed so as to cover the pattern film 405, the conductive transparent thin film 601 supported by the filter 401 is formed from the pattern film 405 and the entire film 404.

  Thereafter, when the conductive transparent thin film 601 is transferred to the substrate 121, the transparent electrode 101 is completed as in the above embodiment.

  At this time, as in the above embodiment, the thickness and thickness of the entire layer 404 are adjusted by adjusting the affinity with the carbon nanotubes on the upstream side of the filter 401 and on the surface of the mask 402 installed on the upstream side. It is possible to make the homogeneity within a desired range, or to perform transfer to the substrate 121 appropriately.

  Initially, the filter 401 is filtered without forming the mask 402 to form the entire membrane 404, and then the mask 402 is placed downstream of the filter 401 or upstream of the entire membrane 404. There is also a method in which the conductive transparent thin film 601 is formed by performing filtration.

  In this method, it is necessary to switch between a state in which the mask 402 is not installed and a state in which the mask 402 is installed for one filter 401, and a conductive material is applied to the filter 401 at the time of switching. Since it adheres, it is more suitable for the technique of using metal foil as the mask 402.

  In this embodiment, a method for forming the conductive layer 141 on the substrate 121 by performing transfer without using the filter 401 will be described.

  In this method, the carbon nanotube is used as a material for forming the flange 161, and the difference in affinity between the carbon nanotube and another material is used. 7A, 7B, and 7C are cross-sectional views showing a state of a transfer procedure using affinity. Hereinafter, description will be given with reference to these drawings.

  As described above, the carbon nanotubes are transferred from the side having low affinity with carbon nanotubes (weak interaction) to the side having high affinity with carbon nanotubes (strong interaction).

  In the present embodiment, the support material 702a supporting the carbon nanotube thin film 701a, the support material 702b supporting the carbon nanotube thin film 701b, the base material 121, and the pattern shape of the ridge 161 on the surface of the base material 121 are represented. Transfer is performed using the difference in the affinity of the four types of the binder 703 coated in this manner. Here, the affinity (interaction) with the carbon nanotubes increases in the order of the support material 702b, the base material 121, the support material 702a, and the binder 703.

  First, as shown in FIG. 7A, a support material 702a is brought close to and in close contact with a base material 121 to which a binder 703 has been applied. Then, the carbon nanotubes of the thin film 701a are transferred from the support material 702a to the binder 703 at a portion facing the binder 703 (the affinity of the binder 703 is stronger than that of the support material 702a). However, in the region facing the base material 121, the carbon nanotubes are not transferred from the support material 702a (the affinity of the support material 702a is stronger than that of the base material 121). By this transfer, a pattern film 405 is formed as shown in FIG. 7B.

  Next, as shown in FIG. 7B, the support material 702b is brought close to and in close contact with the base material 121 on which the flange 161 is formed. Then, the carbon nanotubes of the thin film 701b are transferred from the support material 702b to the ridges 161 and the base material 121 (the affinity between the carbon nanotubes and the affinity of the base material 121 are stronger than those of the support material 702b).

  By this transfer, as shown in FIG. 7C, an entire film 404 covering the pattern film 405 is formed.

  Instead of applying the binder 703, the surface of the base material 121 may be surface-modified into the pattern shape of the ridges 161 to realize the above order of affinity (interaction) strength.

  In the above example, the binder 703 is disposed on the substrate 121. However, the binder is applied to the support material for supporting the carbon nanotubes for transfer in the pattern shape of the ridge 161, and the affinity is utilized. There is also a method of performing transfer. FIG. 8A, FIG. 8B, FIG. 8C, and FIG. 8D are cross-sectional views showing the state of a transfer procedure using affinity. Hereinafter, description will be given with reference to these drawings.

  In the present embodiment, the support material 802a, the support material 802b, the binder 803 applied to the surface of the support material 802b in the pattern shape of the flange 161, and the carbon nanotube thin film 801c are supported. Transfer is performed using the five types of affinity differences between the supporting material 802c and the base material 121. Here, the affinity (interaction) with the carbon nanotubes increases in the order of the support material 802b, the support material 802a, the binder 803, and the base material 121. Moreover, the affinity in the base material 121 is stronger than the affinity in the support material 802c.

  First, as shown in FIG. 8A, a support material 802a that supports a thin film 801a of carbon nanotubes is brought close to and in close contact with a support material 802b in which a binder 803 is applied in a pattern shape of a flange 161.

  Then, as shown in FIG. 8B, a pattern film 405 is formed on the upper surface of the binder 803 of the support material 802b.

  Next, as shown in FIG. 8B, the support member 802 b is brought close to and in close contact with the base material 121.

  Then, as shown in FIG. 8C, the pattern film 405 is transferred to the base material 121.

  Further, as shown in FIG. 8C, the support member 802 c is brought into close contact with the base material 121.

  Then, as shown in FIG. 8D, the entire film 404 is transferred so as to cover the base material 121 and the pattern film 405, and the conductive layer 141 is formed.

  In this method, the surface processing on the substrate 121 itself is not necessary, and the order of the transfer of the entire film 404 and the transfer of the pattern film 405 can be reversed.

  As described above, in the present embodiment, the transparent electrode 101 is manufactured by forming the conductive layer 141 having the ridges 161 and the transmission regions 162 on the base material 121 without using the filter 401 by simple transfer. be able to.

  In the above embodiment, the conductive layer 141 is formed by transferring a conductive material such as carbon nanotube. However, the conductive layer 141 can also be formed without using transfer.

  For example, in order to install the entire film 404 on the base material 121 or the pattern film 405, carbon nanotubes are dispersed in a solvent such as water using a surfactant such as sodium lauryl sulfate, and then sprayed. The spray coat method to apply | coat can be employ | adopted.

  In addition, after applying a paste containing carbon nanotubes on the substrate 121, the surface is shaved using a doctor blade so that the paste has a certain thickness, and then the solvent contained in the paste is removed to remove carbon. It is also possible to form the entire film 404 by leaving only the nanotubes.

  In addition, in order to install the pattern film 405 on the substrate 121 or the entire film 404, a printing technique using an ink containing carbon nanotubes can be used.

  For example, a carbon nanotube-containing ink is purified using a surfactant such as sodium deoxycholate, and this is printed on the surface of the substrate 121 with an inkjet printer, or screen printing is used. By doing so, the pattern film 405 can be formed.

  Note that these methods can be appropriately combined with the above manufacturing method. For example, the formation of the entire film 404 on the base material 121 is performed by transfer, and the formation of the pattern film 405 on the base material 121 uses ink jet printing.

  In addition, in the said Example, although the collar 161 is comprised so that a square grid shape may be made, the aspect of this invention is not restricted to this. For example, various lattice shapes such as a regular triangular lattice, a regular hexagonal lattice, a trapezoidal lattice, a rectangular lattice, and a random lattice can be adopted.

  Moreover, it is also possible to make the ridges 161 parallel lines that do not intersect each other. In this case, an anisotropic transparent electrode 101 having a low sheet resistance in a specific direction but high sheet resistance in a specific direction can be realized.

  In the above embodiment, assuming that the transparent electrode 101 is used in a liquid crystal display or the like, it is assumed that the eyelid 161 cannot be visually recognized by humans.

  However, for example, when realizing a transparent electrode for a solar cell, there is no problem even if the ridge 161 can be visually recognized by a human. In such an embodiment, there is no need to limit the width of the flange 161.

  Therefore, it is sufficient to set the light reflectance at the ridge 161 to be equal to or less than the darkness threshold, the light transmittance to be equal to or less than the opacity threshold, and the light transmittance at the transmission region 162 to be equal to or greater than the transparency threshold.

  The conductive transparent thin film 601 according to the present embodiment is formed on the filter 401 by changing the dimensions and the like in the manufacturing method of the transparent electrode 101, and the conductive layer 141 is disposed on the substrate 121. The transparent electrode 101 can be manufactured, and as described above, the restrictions on specifications can be relaxed.

  According to the present invention, a transparent electrode, a method for producing a conductive transparent thin film, and a conductive transparent thin film can be provided.

DESCRIPTION OF SYMBOLS 101 Transparent electrode 121 Base material 141 Conductive layer 151 1st layer 152 2nd layer 161 畝 162 Transmission area 401 Filter 402 Mask 403 Opening 404 Overall film 405 Pattern film 601 Conductive transparent thin film 701 Carbon nanotube thin film 702 Support material 703 Binder 801 Carbon nanotube thin film 802 Support material 803 Binder

Claims (14)

An insulating base material that transmits light;
A conductive layer disposed on the substrate;
With
The conductive layer has a plurality of wrinkles for reducing sheet resistance,
The width of each of the plurality of wrinkles is a width that cannot be visually recognized,
The reflectance of the light in the plurality of eyelids is a predetermined darkness threshold value or less,
The light transmittance in the plurality of ridges is below a predetermined opacity threshold,
The transparent electrode, wherein a light transmittance in a transmission region between the plurality of ridges is equal to or higher than a predetermined transparent threshold. The transparent electrode according to claim 1,
The transparent electrode, wherein the plurality of wrinkles form a lattice. The transparent electrode according to claim 1,
The conductive layer is formed of carbon nanotubes. A transparent electrode, wherein: The transparent electrode according to claim 3,
The predetermined opacity threshold is a constant of 50 percent or less;
The predetermined transparency threshold is a constant of 80% or more,
The plurality of wrinkles cover 1% to 20% of the conductive layer;
Each of the plurality of ridges has a width of 0.1 μm to 10 μm,
The areal density of the carbon nanotubes in the plurality of ridges is 10 μg / cm ^{2 to} 500 μg / cm ² ,
The transparent density of the carbon nanotube in the transmission region is 0.1 μg / cm ^{2 to} 2 μg / cm ² or less. The transparent electrode according to claim 1,
The conductive layer has a first layer made of a first conductor in contact with the base material, and a second layer made of a second conductor disposed on the first layer,
The transparent electrode, wherein the plurality of wrinkles are formed by disposing the second layer on the first layer. The transparent electrode according to claim 5,
One or both of the first conductor and the second conductor are formed of carbon nanotubes. A transparent electrode, wherein: Forming a transmissive layer comprising a transmissive conductor uniformly spreading on the support material; and
Forming an opaque layer made of an opaque conductor having a pattern on the transparent layer;
With
The light transmittance in the transmissive layer is equal to or greater than a predetermined transparency threshold,
The light transmission in the opaque layer is less than or equal to a predetermined opacity threshold;
The method for producing a conductive transparent thin film, wherein the width of the pattern is a width that cannot be visually recognized. Forming an impermeable layer made of an impermeable conductor having a pattern on a support material;
Forming a transmissive layer made of a transmissive conductor that spreads uniformly on the support material and the impermeable layer;
With
The light transmittance in the transmissive layer is equal to or greater than a predetermined transparency threshold,
The light transmission in the opaque layer is less than or equal to a predetermined opacity threshold;
The method for producing a conductive transparent thin film, wherein the width of the pattern is a width that cannot be visually recognized. A method for producing a conductive transparent thin film according to claim 7 or 8,
Either or both of the transmissive layer and the non-permeable layer are layers composed of carbon nanotubes. A method for producing a conductive transparent thin film, comprising: A method for producing a conductive transparent thin film according to claim 7 or 8,
The transmission layer and the non-transmission layer are layers composed of carbon nanotubes, respectively.
The pattern has a width of 0.1 μm to 10 μm,
The areal density of the carbon nanotubes in the impermeable layer is 10 μg / cm ^{2 to} 500 μg / cm ² ,
The surface density of the carbon nanotubes in the transmissive layer is 0.1 μg / cm ^{2 to} 2 μg / cm ² or less. It is a manufacturing method of the conductive transparent thin film according to claim 10,
The support material is a filter;
The permeable layer and the impermeable layer are both thin films obtained by filtering an aerosol of carbon nanotubes or a dispersion of carbon nanotubes with the filter,
After the transmissive layer and the non-transmissive layer are formed on the filter, the method further comprises a step of transferring the transmissive layer and the non-transmissive layer onto an insulating base material that transmits light. A method for producing a conductive transparent thin film. It is a manufacturing method of the conductive transparent thin film according to claim 11,
An organic or inorganic film mask for forming the pattern is disposed on the front surface or the back surface of the filter. It is a manufacturing method of the conductive transparent thin film according to claim 9 or 10,
The support material is an insulating base material that transmits light,
By filtering the aerosol of carbon nanotubes or the dispersion of carbon nanotubes with a filter, the thin film for the transmission layer and the thin film for the non-transmission layer are formed, and the thin film for the transmission layer After transferring one of the thin film for the impermeable layer onto the substrate, the other of the thin film for the transparent layer and the thin film for the impermeable layer is transferred onto the substrate. A method for producing a conductive transparent thin film, further comprising: A support material;
A conductive layer disposed on the support;
With
The conductive layer has a plurality of wrinkles,
The light transmittance in the plurality of ridges is below a predetermined opacity threshold,
The light transmittance in the transmission region between the plurality of ridges is equal to or greater than a predetermined transparency threshold;
The predetermined opacity threshold is a constant of 50 percent or less;
The predetermined transparency threshold is a constant of 80% or more,
The plurality of wrinkles cover 1% to 20% of the conductive layer.

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