Method for manufacturing transparent electrode using conductive nano-ink and transparent electrode manufactured thereby

Abstract

The present invention relates to a method for manufacturing a transparent electrode using a conductive nano-ink, the method comprising: a step for sequentially stacking a chrome mask (30) having a transparent electrode pattern, a photoresist (10), and a substrate, and exposing the stack to ultraviolet rays; a step for performing development after the ultraviolet ray exposure to form a photoresist having the transparent electrode pattern on the substrate; step a for modifying the photoresist (hereinafter, referred to as a sacrificial layer) having the transparent electrode pattern to remove the hydrophobicity of a conductive nano-ink; step b for applying the conductive nano-ink to the sacrificial layer; step c for removing the residual conductive nano-ink on the upper surface of the sacrificial layer by a spin process; step d for pre-sintering the sacrificial layer to reduce the conductive nano-ink inside the sacrificial layer to a solid state; a step for removing the sacrificial layer to obtain a conductive nano-ink pattern of the transparent electrode pattern; and step e for further heat-treating the conductive nano-ink pattern to improve conductivity.

Description

Method for fabricating a transparent electrode using conductive nano ink and a transparent electrode fabricated thereby

[0001] The present invention relates to a method for fabricating a transparent electrode by forming a transparent electrode pattern on a photosensitive material using a photolithography method, applying a conductive nanoink to the photosensitive material and heat-treating it, and removing the photosensitive material.

[0002]

[0003] Transparent electrode patterns are created by forming a material that has both high transparency and conductivity into a specific shape and utilizing it in various electronic devices. They are mainly used in touchscreens, solar cells, and OLEDs, and recently, they are also being applied to wearable devices and smart windows.

[0004] Generally, the fabrication of a transparent electrode pattern is carried out in the following steps: substrate preparation, transparent electrode material deposition, patterning, and post-processing. The patterning step is a step of forming a pattern of a desired shape using methods such as photolithography, laser cutting, or inkjet printing, and the post-processing step is a step of increasing the stability of the pattern through heat treatment, plasma treatment, etc., as needed.

[0005] Indium Tin Oxide (ITO) is the most widely used transparent electrode material for transparent electrode patterns; while it possesses high transmittance and conductivity, it has the disadvantages of being expensive and lacking flexibility.

[0006] Silver nanowires have high conductivity and flexibility and are attracting attention as a material that can replace ITO, carbon nanotubes have high conductivity and mechanical strength and are suitable for flexible transparent electrodes, and graphene has excellent electrical and mechanical properties but has technical problems that make mass production and ensuring uniform quality difficult.

[0007]

[0008] As mentioned above, the patterning step utilizes methods such as photolithography, laser cutting, and inkjet printing, and we will examine the prior art related thereto below.

[0009] Korean Patent Application No. 10-2015-0041441, 'Method for manufacturing a transparent electrode pattern', forms a transparent electrode pattern by filling a recessed substrate with a conductive nano-ink composition and transferring it twice.

[0010] Korean Patent Application No. 10-2012-0126998, 'conductive nano ink composition, electrode wire and transparent electrode using the same,' forms a pattern using a conductive nano ink by jet printing.

[0011] Korean Patent Application No. 10-2010-0040532, 'Large-area printing method of conductive ink', prints conductive nano-ink using a gravure printing method.

[0012] Korean Patent Application No. 10-2010-0123722, 'Conductive ink and transparent electrode using the same', forms a transparent electrode by wet thin film coating using a carbon structure-based conductive ink.

[0013] Korean Patent Application No. 10-2014-0059281, 'Method for manufacturing a hybrid transparent electrode and a hybrid transparent electrode,' forms a transparent electrode by filling a groove of a substrate having a groove with a conductive metal ink composition.

[0014] Korean Patent Application No. 10-2021-0169160, 'Metal Micro-printing Method and Apparatus,' proposes a printing method capable of producing micro-patterns using the interference phenomenon of a laser beam on MOD ink.

[0015] As such, prior art technologies form transparent electrode patterns by fabricating a stencil with a pre-printed pattern or by directly spraying the pattern; however, these methods have the problem of being complex processes or making it difficult to form large-area transparent patterns of precise microelectrodes.

[0016]

[0017] The present invention aims to solve the aforementioned problems by providing a method for fabricating a transparent electrode using a conductive nano ink, which simplifies and speeds the process and enables the formation of a precise large-area fine transparent electrode pattern by using a method of forming a photosensitive material into a transparent electrode mold through a photolithography process.

[0018]

[0019] To achieve the above objective, the present invention provides a method for fabricating a transparent electrode using a conductive nano-ink, comprising the steps of: sequentially stacking a chrome mask having a transparent electrode pattern, a photosensitive material, and a substrate, and exposing them to ultraviolet light; developing after the ultraviolet light exposure to form a photosensitive material having a transparent electrode pattern on the substrate; modifying the photosensitive material having the transparent electrode pattern (hereinafter referred to as a 'sacrificial layer') to remove hydrophobicity to the conductive nano-ink; applying the conductive nano-ink to the sacrificial layer; removing residual conductive nano-ink on the upper surface of the sacrificial layer by a spin process; pre-sintering the sacrificial layer to reduce the conductive nano-ink inside the sacrificial layer to a solid state; and removing the sacrificial layer to obtain a conductive nano-ink pattern of the transparent electrode pattern and further heat-treating the conductive nano-ink pattern to improve conductivity.

[0020] In the present invention, it is preferable that the method for fabricating a transparent electrode using a conductive nano ink is characterized in that step a is performed by plasma treatment or ozone treatment.

[0021] In the present invention, it is preferable that step b be a method for fabricating a transparent electrode using a conductive nano ink characterized by the conductive nano ink having a solid content dilution ratio of 0.1% by weight to 50% by weight.

[0022] In addition, it is preferable that the spin process of step c above be performed at a spin speed of 1000 rpm or higher to reduce the thickness of the residual conductive nano ink on the upper surface of the sacrificial layer, thereby forming a method for fabricating a transparent electrode using conductive nano ink.

[0023] In addition, it is preferable that the above step d be a method for fabricating a transparent electrode using a conductive nano ink, characterized by having a sintering temperature in the range of 90℃ to 120℃.

[0024] In addition, it is preferable that the method for fabricating a transparent electrode using a conductive nano ink is characterized in that the heat treatment temperature of step e is 120℃ or higher.

[0025] The present invention also has as another technical feature a transparent electrode using conductive nano ink produced by the method for producing a transparent electrode using the above-described conductive nano ink.

[0026]

[0027] According to the present invention described above, there is an advantage in that a method for fabricating a transparent electrode using a conductive nano ink is provided, which simplifies and speeds the process and enables the formation of a precise large-area fine transparent electrode pattern by using a method of forming a photosensitive material into a transparent electrode mold through a photolithography process.

[0028]

[0029] FIG. 1 is an explanatory diagram of an embodiment of the present invention.

[0030]

[0031] The present invention will be examined below with reference to the drawings. In describing the present invention, if it is determined that a detailed description of related known technologies or configurations may unnecessarily obscure the essence of the invention, such detailed description will be omitted.

[0032] Furthermore, the terms described below are defined in consideration of their functions in the present invention; since these may vary depending on the intentions or practices of the user or operator, their definitions should be based on the content throughout this specification describing the present invention.

[0033]

[0034] The present invention will be examined below in conjunction with FIG. 1.

[0035] In FIG. 1, step (S100) of the present invention is a step of sequentially stacking a chrome mask (30) with a transparent electrode pattern formed thereon, a photosensitive material (10), and a substrate (20), and exposing them to ultraviolet light.

[0036] The desired transparent electrode pattern can be fabricated using a chrome mask (30), and can be fabricated with a fine line width of up to 1 µm considering the transmittance.

[0037] The above substrate (20) is a glass substrate, and a substrate (20) on which HMDS (hexamethyldisilane) is deposited is used to increase the adhesion between the photosensitive agent (10) and the glass substrate.

[0038] The above ultraviolet exposure is a process of transferring a fabricated chrome mask (30) onto a photosensitive material (10), and the photosensitive material (10) and the chrome mask (30) are exposed while in close contact, thereby selectively exposing a transparent electrode pattern to the photosensitive material (10).

[0039]

[0040] Step (S200) of the present invention is a step of forming a photosensitive material (10) with a transparent electrode pattern formed on a substrate (20) by developing after the ultraviolet light exposure.

[0041] In the step of immersing the exposed mask in a developing solution to form a transparent electrode pattern on the photosensitive material (10), when using a raised photosensitive material (10), the portion irradiated with ultraviolet light is removed, leaving the photosensitive material (10) in a shape.

[0042]

[0043] Steps (S100) and (S200) are ordinary photolithography methods for forming a transparent electrode pattern on a photosensitive material (10).

[0044] Generally, known technologies form a transparent electrode pattern on a photosensitive material (10) using a photolithography method, but there was a technical problem in that the photosensitive material (10) pattern could not be directly used as a mold to form a transparent electrode due to hydrophobicity and selective removal issues between the photosensitive material (10) and the conductive nanoink.

[0045]

[0046] Step a (S300) of the present invention solves such technical problems by modifying the photosensitive material (10) (hereinafter referred to as 'sacrificial layer (10')') on which the transparent electrode pattern is formed, thereby removing hydrophobicity to the conductive nanoink.

[0047] The above modification can be performed by plasma treatment or ozone treatment of the sacrificial layer (10'), thereby removing hydrophobicity between the photosensitive agent (10) and the conductive nanoink, allowing the conductive nanoink to easily penetrate and fill the pattern inside the sacrificial layer (10').

[0048]

[0049] Step b (S400) of the present invention is a step of penetrating and applying conductive nano ink into the transparent electrode pattern of the sacrificial layer (10') from which hydrophobicity has been removed in step a (S300).

[0050] When conductive nanoink is applied to the sacrificial layer (10'), the height and conductivity of the final structure are determined by the dilution ratio of the applied conductive nanoink.

[0051] Since the conductive nano ink must seep into the pattern groove of the sacrificial layer (10'), it must be applied sufficiently to cover the entire pattern surface of the sacrificial layer (10'), and in one embodiment of the present invention, the conductive nano ink was applied by adjusting the solid content dilution ratio with respect to water to a range of 0.1% by weight to 50% by weight.

[0052]

[0053] Step c (S500) of the present invention is a step of removing residual conductive nanoink on the upper surface of the sacrificial layer (10') by a spin process.

[0054] If residual conductive nano-ink remains on the sacrificial layer (10'), the ink on the upper side may become connected during sintering, and thus the process of removing the sacrificial layer (10') in the subsequent step (S700) may not proceed smoothly; therefore, the ink on the upper side of the pattern must be removed with a sufficient spin speed.

[0055] In one embodiment of the present invention, the spin speed was performed at 1000 rpm or higher to reduce the residual thickness of the conductive nanoink.

[0056] The present invention is characterized by improving ink penetration by modifying the hydrophobicity of a micro-scale transparent electrode pattern to hydrophilicity, determining the final electrode height by adjusting the dilution ratio in step b (S400), and removing residual ink on the surface of the sacrificial layer as much as possible in step c (S500) so that ink remains only in the trenches of the transparent electrode pattern.

[0057]

[0058] Step d (S600) of the present invention is a step of sintering the sacrificial layer (10') to reduce the conductive nanoink inside the sacrificial layer (10') to a solid state.

[0059] In step d (S600), the nano-ink structure is stabilized through sintering and forms adhesion to the substrate (20).

[0060] However, if the process is carried out at too high a temperature, the portion of the photosensitive material (10) that should be removed as a sacrificial layer (10') in the subsequent step (S700) may become too hard and not be erased, so it is necessary to carry out the process at an appropriate temperature.

[0061] In step d (S600), a step difference may occur between the ink and the sacrificial layer due to the evaporation of water during sintering, and this step difference may help in removing the sacrificial layer.

[0062] Accordingly, the above step d of the present invention preferably has a sintering temperature in the range of 90℃ to 120℃.

[0063]

[0064] Step e (S700) of the present invention is a step of removing the sacrificial layer (10') to obtain a conductive nanoink pattern (40') of a transparent electrode pattern.

[0065] In step e (S700), the photosensitive material (10) is immersed in an organic solvent capable of removing it to remove the sacrificial layer (10') and leave only the nano-ink structure.

[0066] The above nano-ink structure is defined below as a conductive nano-ink pattern (40').

[0067] Step e (S700) of the present invention may include a step of improving conductivity by additionally heat-treating the conductive nanoink pattern (40').

[0068] It is preferable that the heat treatment temperature of the above step e be 120℃ or higher.

[0069]

[0070] As described above, the present invention is a method for manufacturing a transparent electrode using conductive nano ink, and is characterized by using a photosensitive material (10) directly as a transparent nano pattern mold.

[0071] In other words, the present invention provides a method for penetrating ink into a fine transparent electrode pattern formed on a photosensitive material and a method for removing residual ink, thereby having the advantage of enabling the photosensitive material to be easily used as a transparent electrode mold in a photolithography process.

[0072] Using the photosensitive transparent electrode mold of the present invention described above has the advantage of being able to obtain a transparent electrode using conductive nano ink.

[0073]

[0074] The drawings illustrated above for the purpose of explaining the present invention are one embodiment in which the present invention is embodied, and it can be seen that various combinations are possible to realize the gist of the present invention as illustrated in the drawings.

[0075] Therefore, the present invention is not limited to the embodiments described above, and the technical spirit of the present invention extends to the scope in which various modifications can be made by anyone with ordinary knowledge in the field to which the invention belongs, without departing from the essence of the invention as claimed in the following patent claims.

Claims

1. A step of sequentially stacking a chrome mask having a transparent electrode pattern, a photosensitive material, and a substrate, and exposing to ultraviolet light; A step of forming a photosensitive material having a transparent electrode pattern formed on a substrate by developing after the above-mentioned ultraviolet exposure; Step a of modifying a photosensitive material (hereinafter referred to as a 'sacrificial layer') having the above-mentioned transparent electrode pattern formed thereon to remove hydrophobicity to the conductive nanoink; Step b of applying conductive nano ink to the sacrificial layer; Step c, which removes residual conductive nanoink on the upper surface of the sacrificial layer using a spin process; Step d, which involves pre-sintering the sacrificial layer to reduce the conductive nano-ink inside the sacrificial layer to a solid state; Step e, which involves removing the sacrificial layer to obtain a conductive nanoink pattern of a transparent electrode pattern and further heat-treating the conductive nanoink pattern to improve conductivity. A method for fabricating a transparent electrode using conductive nano ink, characterized by comprising 2. In paragraph 1, the above step a A method for fabricating a transparent electrode using a conductive nano ink, characterized by being carried out by plasma treatment or ozone treatment.

3. In paragraph 1, the above step b A method for fabricating a transparent electrode using a conductive nano ink characterized by the conductive nano ink having a solid content dilution ratio of 0.1 wt% to 50 wt% with respect to water.

4. In paragraph 1, the spin process of step c is Run at a spin speed of 1000 rpm or higher A method for fabricating a transparent electrode using conductive nano ink, characterized by reducing the thickness of the residual conductive nano ink on the upper surface of the sacrificial layer.

5. In paragraph 1, the above step d A method for fabricating a transparent electrode using a conductive nano ink characterized by having a sintering temperature in the range of 90℃ to 120℃.

6. In Paragraph 1 A method for fabricating a transparent electrode using a conductive nano ink, characterized in that the heat treatment temperature of step e above is 120℃ or higher.

7. A transparent electrode using a conductive nano ink produced according to any one of claims 1 to 6.

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