KR20200056902A - Metal nanowire embedded transparent electrode having concavoconvex structure integrated on both sides and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a transparent electrode which has an integrated concavo-convex structure on both sides and is embedded with metal nanowires, and a method for manufacturing the same. According to the present invention, excellent optical properties can be ensured by the integrated concavo-convex structure on both sides of the transparent electrode.

Description

METAL NANOWIRE EMBEDDED TRANSPARENT ELECTRODE HAVING CONCAVOCONVEX STRUCTURE INTEGRATED ON BOTH SIDES AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a metal nanowire-impregnated transparent electrode having a surface uneven structure for improving optical properties.

The transparent electrode is a conductive thin film having optical and electrical properties, and is a material used in various optoelectronic devices such as displays, solar cells, touch panels, and optical sensors. The optoelectronic device market is rapidly expanding every year due to the development of the IT industry, and the demand for transparent electrodes is also increasing.

Currently, as a transparent electrode material, ITO (Indium Tin Oxide) is most often used due to its excellent optical and electrical properties. However, with the rapid development of modern science and technology, transparent electrodes require not only optical and electrical properties, but also flexibility and wearable properties required for next-generation electronic devices. The ITO thin film has disadvantages that it is not suitable for the next-generation flexible optoelectronic device due to the brittleness of the oxide, and a high process cost occurs due to the high price due to the scarcity of indium resources and high vacuum equipment when manufacturing the ITO thin film. Therefore, there are disadvantages that are difficult to apply to next-generation electronic devices, and various studies on alternative transparent electrodes have been conducted, and there are typically CNTs (carbon nanotubes), graphene, metal nanowires, and conductive polymers.

Among these, metal nanowires have an advantage of being capable of being produced through a solution process as well as excellent optical, electrical, and mechanical properties. In addition, a transparent electrode made by impregnating a metal nanowire with a polymer base has an advantage that can solve the problems of high surface roughness, oxidation, and lack of adhesion with a substrate, which is an existing problem, and is particularly highlighted as an alternative transparent electrode.

On the other hand, in the organic solar cell incorporating a transparent electrode, the donor material in the light absorbing layer receives light to generate excitons (electron-electron pairs), and the excitons move randomly, and then the electrons and electrons at the interface between the donor material and the acceptor material. It is a principle that is separated into holes, moves to an electrode, and generates electricity. At this time, the life of the exciton is very short, and the light absorbing layer of the organic solar cell is inevitably designed to be 50 to 300 nm thin. Since the light absorbing layer does not sufficiently absorb the incident light, the organic solar cell exhibits a problem of exhibiting low current density characteristics. Therefore, in order to commercialize the organic solar cell, improvement of light absorption efficiency is a problem that must be solved.

Accordingly, various studies have been conducted for this purpose, and representative examples include the development of a new light absorbing layer material, control of interfacial properties, and optical design through the introduction of a physical structure. Among them, the introduction of the physical structure is a method of controlling the optical behavior of light incident through the physical structure without changing the thickness of the light absorbing layer, and has a simple and effective advantage compared to other methods. Specifically, the light incident on the transparent electrode of the organic solar cell is refracted, scattered and re-reflected by the physical structure, thereby reducing light loss and increasing the optical path inside, thereby increasing light absorption.

As a conventional method for introducing such a physical structure, there is a method using photolithography, or a method of attaching and laminating separate physical structures. However, in the case of a method using photolithography, the process is complicated and requires expensive equipment. In addition, in the case of a method of attaching and stacking a separate physical structure, processes such as manufacturing and stacking of the physical structure are additionally required, and the process is complicated, and the manufactured transparent electrode has optical characteristics due to a difference in refractive index of the physical structure. There is a problem of deterioration.

Accordingly, there is a need for a transparent electrode having excellent optical properties and capable of significantly improving the light absorption and light efficiency of an optoelectronic device, and an optimal method that can be manufactured more simply and without expensive equipment.

Republic of Korea Patent Publication No. 10-2018-0057898

The present invention is to solve the above-mentioned problem, and unlike the conventional method using photolithography, a method of manufacturing a transparent electrode having uneven structures formed on both surfaces in a simpler process without expensive equipment The purpose is to provide.

In addition, the present invention is to provide a method of manufacturing a transparent electrode in which uneven structures are integrally formed on both sides without a separate process of stacking physical structures.

In addition, an object of the present invention is to provide a method of manufacturing a transparent electrode in which a fine, rugged, fine uneven structure is integrally formed on both sides.

In addition, an object of the present invention is to provide a transparent electrode having excellent optical properties and capable of significantly improving light absorption and light efficiency when applied to an optoelectronic device.

In order to achieve the above object, the present invention, (a) forming a first cured resin layer having a concavo-convex structure on the upper surface by transfer and curing on the substrate, (b) the first cured resin layer On, forming a release layer having a shape of the uneven structure, (c) forming a metal nanowire layer having the shape of the uneven structure on the release layer, (d) the metal nano Forming a second cured resin layer having a concavo-convex structure on the upper surface by transfer and curing, and impregnating the metal nanowires, and (e) separating the second cured resin layer to form an upper surface and It provides a method of manufacturing a transparent electrode, including the step of obtaining a cured film having an uneven structure on the lower surface and impregnated with metal nanowires.

According to an example of the present invention, the step (a) or (d) is not particularly limited, forming a curable resin layer; Adhering a siloxane-based resin mold having an uneven structure to the curable resin layer; Curing the curable resin layer; And removing the siloxane-based resin mold.

At this time, the uneven structure of the siloxane-based resin mold is not particularly limited, but may be a microlens array structure.

In addition, the diameter of each microlens constituting the microlens array structure of the siloxane-based resin mold in the step (a) is not particularly limited as long as the object of the present invention is achieved, but is not limited to 0.1 to 10 μm. Can be

In addition, the diameter of each microlens constituting the microlens array structure of the siloxane-based resin mold in the step (d) is not particularly limited as long as the object of the present invention is achieved, but is 3 to 30 μm. Can be

In addition, the present invention, as a transparent electrode comprising a cured film, the cured film has a concavo-convex structure on the upper and lower surfaces, and the metal nanowires are impregnated.

According to an example of the present invention, the uneven structure is not particularly limited, but may be a microlens array structure.

At this time, the diameter of each micro-lens constituting the micro-lens array structure on the top surface of the cured film is not particularly limited as long as the object of the present invention is achieved, but may be 3 to 30 μm.

In addition, the diameter of each microlens constituting the microlens array structure of the lower surface of the cured film is not particularly limited, but may be 0.1 to 10 μm, as long as the objective of the present invention is achieved.

In the case of the present invention, unlike the conventional method using photolithography or the like, a transparent electrode having an uneven structure on both surfaces can be manufactured in a simple process without expensive equipment.

In addition, in the case of the present invention, a transparent electrode having an uneven structure on both surfaces can be manufactured simply and efficiently, without a separate process of stacking physical structures.

In addition, the present invention provides an optimal method for manufacturing a transparent electrode in which a fine and rugged fine uneven structure is integrally formed on both sides.

In addition, the present invention provides a transparent electrode that has excellent optical properties due to an integrated uneven structure on both sides, and can significantly improve light absorption and light efficiency when applied to an optoelectronic device.

All terms used in this specification (including technical and scientific terms) may be used in a sense that can be commonly understood by those of ordinary skill in the art to which the present invention belongs, unless otherwise defined. When a certain part of the specification "includes" a certain component, this means that other components may be further included instead of excluding other components unless specifically stated otherwise. Also, the singular form includes the plural form unless otherwise specified in the phrase.

In the present invention, "concave-convex structure" may mean that the concave and convex portions are formed periodically, regularly, or randomly, and there is no particular limitation on the shape. As a specific example, as the uneven structure, various structures such as a lattice structure, a wrinkle structure, and a micro lens array structure may be adopted and applied.

"Incompatibility" in the present invention means that they have no release properties because they are not compatible with each other and have different solubility parameters.

Specifically, it means that Δδ, which is a difference in solubility constant, satisfies Expression 2 below.

[Equation 2]

2 ≤Δδ

In Equation 2, the unit is J ^1/2 / cm ^2/3 .

In the present invention, the term "release properties" means that they are loosely attached to each other and can be easily removed by applying a physical force using a finger or a cotton swab.

The present invention relates to a transparent electrode and a method for manufacturing the same, including a cured film having an uneven structure on both sides and impregnated with metal nanowires.

Specifically, the present invention, (a) forming a first cured resin layer having an uneven structure on the upper surface by transfer and curing on a substrate, (b) on the first cured resin layer, the unevenness Forming a release layer having a shape of a structure, (c) forming a metal nanowire layer having the shape of the uneven structure, on the release layer, (d) on the metal nanowire layer, Forming a second cured resin layer having an uneven structure on the upper surface by transfer and curing and impregnating metal nanowires, and (e) separating the second cured resin layer, thereby forming an uneven structure on the upper and lower surfaces It provides a method of manufacturing a transparent electrode, comprising, the step of obtaining a cured film, impregnated with metal nanowires.

According to the present invention, due to the incompatibility between the release layer and the metal nanowire layer, the metal nanowire can be more easily impregnated with the second cured resin layer. Accordingly, a cured film impregnated with metal nanowires can be manufactured simply and easily.

In addition, due to the releasability between the release layer and the second cured resin layer, the second cured resin layer can be easily separated from the release layer. Accordingly, when separating, the finely uneven structures existing on the upper and lower surfaces of the second cured resin layer can be precisely maintained, so that the separated cured film can have fine and fine uneven structures on both sides.

The cured film of the present invention may be used as a transparent electrode by itself, or may be used as a composite transparent electrode by laminating another film or forming a film. However, the cured film of the present invention is characterized by having excellent optical properties when used as a transparent electrode itself.

In addition, in the case of the present invention, a transparent electrode having an uneven structure on both surfaces can be manufactured without a separate physical structure manufacturing and laminating process, and the process is simpler. In addition, unlike the conventional method, an uneven structure can be formed without expensive equipment, and thus, an optimal method can be provided in the production of a transparent electrode having an uneven structure on both sides.

Hereinafter, the present invention will be described in more detail.

The substrate of the present invention is not particularly limited, but may be any one selected from silicon substrates, quartz substrates, glass substrates, silicon wafers, polymer substrates, metal substrates, and metal oxide substrates.

The polymer substrate is not particularly limited, and a film substrate such as polyethylene terephthalate, polycarbonate, polyimide, polyethylene naphthalate, and cycloolefin polymer may be used. However, a glass substrate or a silicon wafer that can be easily manufactured and supplied may be preferred.

The first cured resin layer of the present invention can be formed by applying a curable resin on a substrate to form a curable resin layer, and forming an uneven structure through transfer and curing on the upper surface of the curable resin layer.

The curable resin is not particularly limited, but may be any one selected from ultraviolet curable resin, thermosetting resin, room temperature moisture curable resin, and infrared curable resin.

However, more specifically, the curable resin may be an ultraviolet curable resin, and at this time, as the ultraviolet curable resin, as long as it has a property of being completely cured upon exposure to ultraviolet light, it is not particularly limited and may be adopted. More specific examples include NOA60, NOA61, NOA63, NOA65, NOA68, NOA68T, NOA71, NOA72, NOA73, NOA74, NOA75, NOA76, NOA78, NOA81, NOA83H, NOA84, NOA85, NOA85V, NOA86 from the Norland Optical Adhesive series of Norland Products , NOA86H, NOA87, NOA88, NOA89, and the like, but are not limited thereto.

The coating method is not particularly limited, but a method such as spin coating, bar coating, and roll-to-roll coating may be employed.

As the transfer method, a soft lithography printing method or a soft lithography molding method may be used.

More specifically, although not particularly limited thereto, the printing method may be a printing method such as microcontact printing, decal transfer microlithography, light stamp, or the like, and the molding method. Silver, replica molding, capillary force lithography, capillary micromolding in capillaries, microtransfer molding, nano imprinting, liquid-mediated transfer molding It may be a molding method such as mediated nanotransfer molding.

The release layer of the present invention can be formed by applying a hydrophobic resin on the first cured resin layer having an uneven structure on the upper surface. At this time, curing may be further performed.

The release layer is characterized in that the shape is controlled according to the uneven structure on the upper surface of the first cured resin layer, and has the shape of the uneven structure. At this time, the coating may be any of the coating methods in which the shape of the release layer can be controlled according to the uneven structure, but as an easier method for this, the spin coating method may be preferred.

As the hydrophobic resin, as long as the object of the present invention is achieved, that is, it has incompatibility with the metal nanowire layer and has a release property with the second cured resin layer, it can be adopted without particular limitation.

More specifically, the hydrophobic resin, olefin-based resin, vinyl-based resin, polyester-based resin, polyurethane-based resin, polyamide-based resin, polyimide-based resin, cellulose-based resin, silicone-based resin, polysulfone-based resin, polyether It may be a sulfone-based resin, a polyacetal-based resin and a poly (meth) acrylic resin selected from one, or two or more copolymers. However, it is not limited thereto.

In the present invention, in order to ensure incompatibility between the release layer and the second cured resin layer, the solubility constant δ ₁ of the hydrophobic resin forming the release layer and the curable resin layer forming the cured resin layer is not particularly limited. Solubility constant of δ ₂ The difference value, Δδ of Equation 1 below may satisfy Equation 2 below.

[Equation 1]

Δδ = | δ _2- δ ₁ |

[Equation 2]

2 ≤Δδ

In Equation 2, the unit is J ^1/2 / cm ^2/3 .

The solubility constant can be calculated according to the method described by Hoftyzer-Van Krevelen in Van Krevelen's book (Van Krevelen, "Properties of Polymers: Their Correlation with Chemical Structure", 3rd Ed, Elsevier, 1990).

The metal nanowire layer of the present invention can be formed by coating a metal nanowire dispersion on a release layer having a concavo-convex structure and drying it.

The metal nanowire layer is characterized in that the shape is controlled according to the shape of the release layer having the shape of the uneven structure, and thus has the shape of the uneven structure. At this time, the application, any coating method that can control the shape of the metal nanowire layer according to the uneven structure may be employed, but as an easier method for this, a spin coating method may be preferred. In this case, it is not particularly limited, but may be spin coated at 500 to 700 rpm for 30 seconds to 2 minutes, and heat treated at 80 to 110 ° C for 30 seconds to 2 minutes.

The metal nanowire dispersion is not particularly limited, but the metal nanowire may be 0.1 to 1.0 wt% dispersed in any one or more solvents selected from purified water, ethanol, isopropyl alcohol, and butyl carbitol.

In addition, the metal nanowires are not particularly limited, but silver (Ag), copper (Cu), aluminum (Al), gold (Au), platinum (Pt), nickel (Ni), titanium (Ti), and these It may be any one selected from alloys. In this case, the diameter of the metal nanowire is not particularly limited, but may be 10 to 50 nm, a length of 10 to 50 μm, and an aspect ratio of 500 to 800.

The second cured resin layer of the present invention, after forming a curable resin layer by applying a curable resin on a metal nanowire layer having a shape of an uneven structure, after transferring and curing the curable resin layer on the upper surface of the curable resin layer By forming, it can be formed.

At this time, due to the incompatibility and releasability between the release layer and the metal nanowire layer, there is a feature that the metal nanowires are easily impregnated with the curable resin layer.

The curable resin is not particularly limited, but may be any one selected from ultraviolet curable resin, thermosetting resin, room temperature moisture curable resin, and infrared curable resin. However, in order to form a cured film having excellent transmittance without inhibiting the physical properties of the metal nanowire, it may be an ultraviolet curable resin.

The ultraviolet curable resin may be adopted without particular limitation, as long as it has a property of being completely cured upon exposure to ultraviolet light. More specific examples include NOA60, NOA61, NOA63, NOA65, NOA68, NOA68T, NOA71, NOA72, NOA73, NOA74, NOA75, NOA76, NOA78, NOA81, NOA83H, NOA84, NOA85, NOA85V, NOA86 from the Norland Optical Adhesive series of Norland Products , NOA86H, NOA87, NOA88, NOA89, and the like, but are not limited thereto.

As a method of applying, the method is not particularly limited, but is not particularly limited, and spin coating, bar coating, roll-to-roll coating, or the like may be employed.

However, it is not particularly limited, but for the production of a uniform thickness cured film and a transparent electrode, a spin coating method may be more preferred. In this case, the spin coating speed should be adjusted differently depending on the viscosity and weight of the curable resin used. As a specific example, in the case of NOA63 of 2500 cps of Norland Products, when 0.1 to 5 g is used, it can be coated with a uniform thickness, regardless of the weight in the range from 500 rpm or more.

As the transfer method, a soft lithography printing method or a soft lithography molding method may be used.

More specifically, although not particularly limited thereto, the printing method may be a printing method such as microcontact printing, decal transfer microlithography, light stamp, or the like, and the molding method. Silver, replica molding, capillary force lithography, capillary micromolding in capillaries, microtransfer molding, nano imprinting, liquid-mediated transfer molding It may be a molding method such as mediated nanotransfer molding.

In one example of the present invention, the step (a) or (d) comprises: forming a curable resin layer; Adhering a siloxane-based resin mold having an uneven structure to the curable resin layer; Curing the curable resin layer; And removing the siloxane-based resin mold.

In this case, by using a siloxane-based resin mold that is an elastic body and has a low surface energy, uniform adhesion is possible and separation is easy, so that a fine fine concavo-convex structure can be more easily formed. In addition, the siloxane-based resin mold has a high light transmittance and is easy to use UV curing, so that it is possible to form a solid uneven structure. In addition, there is an advantage that can be made in a simple process, without the need for expensive equipment.

The said curable resin layer can be formed by apply | coating curable resin, and the specific description about the said curable resin and its application method has already been mentioned above, and the detailed description is abbreviate | omitted here.

The siloxane-based resin mold may mean a mold containing a siloxane-based resin, for example, polydimethylsiloxane as a constituent component.

The uneven structures of the siloxane-based resin molds in steps (a) and (d) may be the same as each other or may be different from each other. Further, even if the uneven structure is the same, the specific shape, for example, the diameter may be different. However, since the optical characteristics of the transparent electrode are different depending on the uneven structure of the upper surface and the lower surface, for the optimal uneven structure, the uneven structure of each siloxane resin mold may be different from each other at least in a specific shape. have.

The concavo-convex structure of the siloxane-based resin mold is not particularly limited as long as the object of the present invention is achieved, and any of them can be adopted and applied. As a specific example, a microlens array structure, a wrinkle structure, a grid structure, etc. may be adopted and applied.

However, in accordance with an example of the present invention, the uneven structure is not particularly limited, but may be a microlens array structure capable of stably securing an increased optical path when the optoelectronic device of the transparent electrode is applied.

At this time, the diameter of each microlens constituting the microlens array structure of the siloxane-based resin mold in the step (a) is not particularly limited, but is 0.1 to 10 μm, more preferably 0.1 to 5 μm, and more More preferably, it may be 0.1 to 3 μm. In this case, there is an advantage that a transparent electrode having particularly excellent optical properties can be manufactured.

In addition, the diameter of each microlens constituting the microlens array structure of the siloxane-based resin mold in the step (d) is not particularly limited, but is 3 to 30 μm, more preferably 5 to 20 μm, and more It may be more preferably 7 to 20 μm. In this case, a transparent electrode having particularly excellent optical properties can be manufactured.

In one example of the present invention, prior to the step of adhering the siloxane-based resin mold, the method may further include preparing the siloxane-based resin mold.

As a step of preparing the siloxane-based resin mold, any method of manufacturing a mold that can be employed in the art may be adopted and applied without any particular limitation.

However, in one example of the present invention, the step of preparing the siloxane-based resin mold is not particularly limited, but the step of preparing a master substrate having an uneven structure; Pouring and curing a siloxane-based resin on the master substrate; And separating the cured siloxane-based resin; may be to include. In this case, more simply, there is an advantage that can continuously and stably provide a siloxane-based resin mold having a fine and sophisticated uneven structure.

The master substrate is not particularly limited, but may be manufactured through a water transfer process or a rubbing process. In addition, the material can also be selected from various materials such as polymer, rubber, metal, etc. without particular limitation.

The siloxane-based resin is not particularly limited, but as a specific example, polydimethylsiloxane may be used. In this case, the curing is not particularly limited, but may be performed at 70 to 100 ° C. for 12 to 36 hours.

In addition, the present invention, as a transparent electrode comprising a cured film, the cured film has a concavo-convex structure on the upper and lower surfaces, and the metal nanowires are impregnated.

The transparent electrode of the present invention may be the cured film itself, or another film may be further laminated or a film formed thereon to be composited. However, the cured film itself is characterized by having excellent optical properties when used as a transparent electrode.

The transparent electrode of the present invention can be employed in various optoelectronic devices such as solar cells, organic light emitting diodes (OLEDs), surface lighting, e-papers, e-books, touch panels, and display substrates.

The transparent electrode of the present invention has a concavo-convex structure on both sides, and thus has an advantage of significantly improved optical properties compared to a conventional transparent electrode, for example, a transparent electrode without concavo-convex structure, and a transparent electrode having a concavo-convex structure on one side. have.

In addition, when the cured film itself is used as a transparent electrode, it has an uneven structure and, unlike a conventional transparent electrode with a separate physical structure, there is an advantage that there is no deterioration in optical properties due to a difference in refractive index. Accordingly, an optoelectronic device such as a solar cell employing this may have excellent light absorption, current density, and light efficiency characteristics.

More specifically, the transparent electrode of the present invention has a high dispersion transmittance value compared to the total transmittance due to the uneven structure on both sides. Therefore, the optoelectronic device to which it is applied can have excellent current density and light efficiency by improving light absorption rate due to an increased optical path.

In addition, when the transparent electrode of the present invention is applied to an organic solar cell, the light that is not absorbed by the light absorbing layer and transmitted is also reflected by the back electrode, and the bottom and top surfaces of the transparent electrode are formed by the uneven structure on both sides of the transparent electrode. Double reflection and scattering may occur. This allows light that has not been absorbed by the light absorbing layer to reach the light absorbing layer repeatedly, so that it can be absorbed. Therefore, the effect as described above can be further increased compared to a transparent electrode having no uneven structure or formed only on one surface.

The cured film may mean a film obtained by curing a curable resin. In this case, the curable resin is not particularly limited, but may be any one selected from ultraviolet curable resin, thermosetting resin, room temperature moisture curable resin, and infrared curable resin. The UV curable resin is not particularly limited, and as a specific example, NOA60, NOA61, NOA63, NOA65, NOA68, NOA68T, NOA71, NOA72, NOA73, NOA74, NOA75, NOA76, NOA78 of the Norland Optical Adhesive series of Norland Products , NOA81, NOA83H, NOA84, NOA85, NOA85V, NOA86, NOA86H, NOA87, NOA88, NOA89, etc.

The metal nanowires are not particularly limited, but silver (Ag), copper (Cu), aluminum (Al), gold (Au), platinum (Pt), nickel (Ni), titanium (Ti), and alloys thereof It can be any one selected from. In this case, the diameter of the metal nanowire is not particularly limited, but may be 10 to 50 nm, a length of 10 to 50 μm, and an aspect ratio of 500 to 800.

As the uneven structure, various structures may be adopted and applied without particular limitations, provided that the object of the present invention is achieved. As a more specific example, as the concavo-convex structure, a micro lens array structure, a wrinkle structure, a lattice structure, or the like may be adopted.

However, according to an example of the present invention, the concavo-convex structure is not particularly limited, but may be a microlens array structure capable of stably securing an increased optical path when an optoelectronic device of a transparent electrode is applied.

At this time, the diameter of each micro-lens constituting the micro-lens array structure on the upper surface of the cured film is not particularly limited as long as the object of the present invention is achieved, 3 to 30 μm, more preferably 5 To 20 μm, even more preferably 7 to 20 μm. In this case, the transparent electrode of the present invention may have better optical properties, and thus, an optoelectronic device having excellent light absorption, current density, and light efficiency may be provided.

In addition, the diameter of each microlens constituting the microlens array structure on the lower surface of the cured film is not particularly limited as long as the object of the present invention is achieved, but is preferably 0.1 to 10 μm, more preferably 0.1 to 10 μm. 5 μm, even more preferably 0.1 to 3 μm. In this case, the transparent electrode of the present invention may have better optical properties, and thus, an optoelectronic device having excellent light absorption, current density, and light efficiency may be provided.

In particular, when the diameter of the microlens on the upper surface of the cured film is 7 to 20 μm, and the diameter of the microlens on the lower surface of the cured film is 0.1 to 5 μm, more preferably 0.1 to 3 μm, the cured film itself Particularly, an optoelectronic device having excellent optical properties and using it as a transparent electrode can have excellent light absorption and light efficiency.

Hereinafter, preferred examples and comparative examples of the present invention will be described. However, the following examples are only preferred examples of the present invention, and the present invention is not limited to the following examples.

<Evaluation method-Evaluation of optical properties of transparent electrode>

UV-Visible-NiR spectroscopy (Agilent, Cary-5000) was used. Light of 300 to 800 nm was irradiated on the upper surface of the transparent electrode, and the total transmittance, linear transmittance and reflectivity were measured, and the average value thereof was calculated.

In addition, the dispersion transmittance and transmission efficiency were calculated therefrom. Here, the transmission efficiency refers to a value of distributed transmittance compared to total transmittance. Dispersion permeability and permeation efficiency were calculated as follows.

Dispersion Permeability (%) = Total Permeability (%)-Straight Permeability (%)

Transmission efficiency (%) = dispersion transmittance (%) / total transmittance (%) × 100

[Production Example-Fabrication of a PDMS mold with a microlens array structure formed on the surface]

As a master substrate, a mold having a concave / convex microlens array structure produced through a water transfer or rubbing process was used. The diameter of the microlens forming the microlens array structure was 0.5, 3, 5, 7, 10, 15, 20 μm for each master substrate. PDMS monomer and PDMS initiator of Sylgard 184 silicone elastomer kit (Dow cornung) were prepared by mixing in a ratio of 10: 1. On the underside of the Petri dish, the master substrate was fixed with the microlens array structure of the master substrate facing upward, and the prepared PDMS was poured. Then, it was cured at a temperature of 80 ° C. for 12 hours. PDMS mold production was completed by separating the cured PDMS from the master substrate.

The 2.5 cm × 3 cm glass substrates were washed with acetone, isopropyl alcohol and ultrasonic cleaner at 60 ° C. for 15 minutes each. Thereafter, the washed glass substrate was placed in an oven at 100 ° C. to remove the residue.

Then, 1 g of a polyurethane (PU) -based NOA63 (Norland Products) was applied to the glass substrate as a photocurable polymer, and spin-coated at 500 rpm for 1 minute to form a first NOA63 layer. Subsequently, on the first NOA63 layer, in a state in which the PDMS mold (concave, 0.5 μm diameter of the microlens) fabricated above is in close contact, the first NOA63 layer is cured by exposure to 365 nm UV for 30 minutes, and the PDMS mold is removed. Thus, a microlens array structure (convex) was formed on the top surface of the first NOA63 layer.

Subsequently, on the first NOA63 layer, 300 µl of polymethyl methacrylate (PMMA, Microchem) was applied using a micropipette, spin-coated for 60 seconds at 3000 rpm, and then heat-treated at 180 ° C. for 30 seconds, A PMMA release layer was formed. At this time, it was confirmed that the shape of the PMMA release layer was controlled along the microlens array structure formed on the top surface of the first NOA63 layer.

Subsequently, a silver pipe with a diameter of 35 ± 5 nm, a length of 20 ± 5 μm, an aspect ratio of 500 or more, and 0.3 wt% of silver nanowires (Nano Pixis) dispersed in purified water (DI water), and a micropipette with a silver nanowire dispersion on the PMMA release layer After 500 µl application, spin coating was performed for 60 seconds at 600 rpm, and heat treatment was performed at 100 ° C for 1 minute to form a silver nanowire layer. At this time, it was confirmed that the shape of the silver nanowire layer was also controlled according to the shape of the PMMA release layer, that is, the microlens array structure formed on the top surface of the first NOA63 layer.

Subsequently, on the silver nanowire layer, 1 g of NOA63 was applied, spin-coated at 500 rpm for 1 minute, and a microlens array structure (concave) was formed on the bottom surface, and the second NOA63 layer impregnated with the silver nanowire was formed. Formed.

Then, on the second NOA63 layer, in a state in which the PDMS mold (convex, microlens diameter 10 μm) is closely adhered, the second NOA63 layer is cured by exposure to UV at 365 nm for 30 minutes, and the PDMS mold is removed to remove 2 A microlens array structure (concave) was formed on the top surface of the NOA63 layer.

Thereafter, the second NOA63 layer was separated from the PMMA release layer, and the silver nanowires were impregnated, and the microlens array structure (concave, microlens diameter 10 μm) on the top surface, and the microlens array structure (concave, microlens surface) A NOA63 film having a diameter of 0.5 μm) was formed. This was used as a transparent electrode.

The above process is repeated with different PDMS molds, and the microlens array structure (concave, microlens diameter 10 μm) on the upper surface and the microlens array structure (concave, microlens diameter 3, 5, 7 μm respectively) on the lower surface. Three transparent electrodes formed were further manufactured.

The optical properties of the prepared transparent electrode were evaluated according to the evaluation method, and are listed in Table 1.

In Example 1, the PDMS mold is different, and the same procedure as in Example 1 is performed, except that a transparent electrode is formed on which an upper surface microlens array structure (convex) and a lower surface microlens array structure (convex) are formed. Did.

The optical properties of the prepared transparent electrode were evaluated according to the evaluation method, and are listed in Table 1.

In Example 1, by performing a PDMS mold, the same procedure as in Example 1 was performed, except that a transparent electrode having a top microlens array structure (convex) and a bottom microlens array structure (concave) was formed. Did.

The optical properties of the prepared transparent electrode were evaluated according to the evaluation method, and are listed in Table 1.

In Example 1, by performing a PDMS mold, the same procedure as in Example 1 was performed, except that a transparent electrode having a top microlens array structure (concave) and a bottom microlens array structure (convex) was formed. Did.

The optical properties of the prepared transparent electrode were evaluated according to the evaluation method, and are listed in Table 1.

[Comparative Example 1]

The 2.5 cm × 3 cm glass substrates were washed with acetone, isopropyl alcohol and ultrasonic cleaner at 60 ° C. for 15 minutes each. Thereafter, the washed glass substrate was placed in an oven at 100 ° C. to remove the residue.

Subsequently, 300 μl of polymethyl methacrylate (PMMA, Microchem) was applied to the glass substrate using a micropipette, spin-coated for 60 seconds at 3000 rpm, and then heat-treated at 180 ° C. for 30 seconds to form a PMMA release layer. Formed.

Subsequently, a silver pipe with a diameter of 35 ± 5 nm, a length of 20 ± 5 μm, an aspect ratio of 500 or more, and 0.3 wt% of silver nanowires (Nano Pixis) dispersed in purified water (DI water), and a micropipette with a silver nanowire dispersion on the PMMA release layer After 500 µl of the coating was used, spin coating was performed for 60 seconds at 600 rpm, and heat treatment was performed at 100 ° C. for 1 minute to form a silver nanowire layer.

Thereafter, 1 g of NOA63 was applied onto the silver nanowire layer, and spin-coated at 500 rpm for 1 minute to form a NOA63 layer impregnated with the silver nanowire.

Thereafter, the NOA63 layer was separated from the PMMA release layer to prepare a NOA63 film impregnated with silver nanowires. This was used as a transparent electrode.

The optical properties of the prepared transparent electrode were evaluated according to the evaluation method, and are listed in Table 2.

[Comparative Example 2]

The 2.5 cm × 3 cm glass substrates were washed with acetone, isopropyl alcohol and ultrasonic cleaner at 60 ° C. for 15 minutes each. Thereafter, the washed glass substrate was placed in an oven at 100 ° C. to remove the residue.

Subsequently, 300 μl of polymethyl methacrylate (PMMA, Microchem) was applied to the glass substrate using a micropipette, spin-coated for 60 seconds at 3000 rpm, and then heat-treated at 180 ° C. for 30 seconds to form a PMMA release layer. Formed.

Subsequently, silver nanowires (nano pixis) having a diameter of 35 ± 5 nm, length of 20 ± 5 μm, and an aspect ratio of 500 or more are 0.3 wt% dispersed in purified water (DI water), and 500 μl of silver nanowire dispersion is applied onto the PMMA release layer. Then, spin coating was performed for 60 seconds at 600 rpm, and heat treatment was performed at 100 ° C. for 1 minute to form a silver nanowire layer.

Thereafter, 1 g of NOA63 was applied onto the silver nanowire layer, and spin-coated at 500 rpm for 1 minute to form a NOA63 layer impregnated with the silver nanowire.

Then, on the NOA63 layer, in a state in which a PDMS mold (convex, 0.5 μm in diameter of the microlens) is in close contact, the NOA63 layer is cured by exposing to UV at 365 nm for 30 minutes, and the PDMS mold is removed, and the microparticles on the top surface of the NOA63 layer A lens array structure (concave) was formed.

Then, the NOA63 layer was separated from the PMMA release layer, and a silver nanowire was impregnated, and a 0.5 μm diameter microlens array structure (concave) was formed only on the top surface, thereby producing a NOA63 film. This was used as a transparent electrode.

The above process is repeated with different PDMS molds only, and additional 6 transparent electrodes with microlens array structures (concave and microlens diameters of 3, 5, 7, 10, 15, 20 μm, respectively) are formed only on the top surface. It was prepared.

The optical properties of the prepared transparent electrode were evaluated according to the evaluation method, and are listed in Table 2.

[Comparative Example 3]

The 2.5 cm × 3 cm glass substrates were washed with acetone, isopropyl alcohol and ultrasonic cleaner at 60 ° C. for 15 minutes each. Thereafter, the washed glass substrate was placed in an oven at 100 ° C. to remove the residue.

Thereafter, 1 g of NOA63 (Norland Products) was applied to the glass substrate, and spin coating was performed at 500 rpm for 1 minute to form a first NOA63 layer. Subsequently, the PDMS mold prepared above (concave, 0.5 μm diameter of microlens) was in close contact with the first NOA63 layer, and exposed to UV at 365 nm for 30 minutes to cure the first NOA63 layer and remove the PDMS mold, A microlens array structure (convex) was formed on the top surface of the first NOA63 layer.

Subsequently, 300 µl of polymethyl methacrylate (PMMA, Microchem) was applied onto the first NOA63 layer using a micropipette, spin-coated for 60 seconds at 3000 rpm, and then heat-treated at 180 ° C. for 30 seconds, PMMA A release layer was formed. At this time, it was confirmed that the shape of the PMMA release layer was controlled along the microlens array structure formed on the top surface of the first NOA63 layer.

Subsequently, a silver pipe with a diameter of 35 ± 5 nm, a length of 20 ± 5 μm, an aspect ratio of 500 or more, and 0.3 wt% of silver nanowires (Nano Pixis) dispersed in purified water (DI water), and a micropipette with a silver nanowire dispersion on the PMMA release layer After 500 µl of the coating was used, spin coating was performed for 60 seconds at 600 rpm, and heat treatment was performed at 100 ° C. for 1 minute to form a silver nanowire layer. At this time, it was confirmed that the shape of the silver nanowire layer was also controlled according to the shape of the PMMA release layer, that is, the microlens array structure formed on the top surface of the first NOA63 layer.

Subsequently, on the silver nanowire layer, 1 g of NOA63 was applied, spin-coated at 500 rpm for 1 minute, and a microlens array structure (concave) was formed on the bottom surface, and the second NOA63 layer impregnated with the silver nanowire was formed. Formed.

Subsequently, the second NOA63 layer was separated from the PMMA release layer, and a silver nanowire was impregnated and a microlens array structure (concave) having a diameter of 0.5 μm was formed only on the bottom surface to prepare a NOA63 film. This was used as a transparent electrode.

The above process is repeated with different PDMS molds, and additional 6 transparent electrodes are formed on the bottom surface only with microlens array structures (3, 5, 7, 10, 15, and 20 μm in diameter, respectively). It was prepared.

The optical properties of the prepared transparent electrode were evaluated according to the evaluation method, and are listed in Table 2.

[Comparative Example 4]

In Comparative Example 2, the PDMS mold was different, except that a transparent electrode having a microlens array structure (convex) formed only on the top surface was prepared, and was performed in the same manner as in Comparative Example 2.

The optical properties of the prepared transparent electrode were evaluated according to the evaluation method, and are listed in Table 2.

[Comparative Example 5]

In Comparative Example 3, the PDMS mold was changed, and the same procedure was performed as in Comparative Example 3, except that a transparent electrode in which a microlens array structure (convex) was formed only on the lower surface was manufactured.

The optical properties of the prepared transparent electrode were evaluated according to the evaluation method, and are listed in Table 2.

diameter Total transmittance Straight Transmittance Dispersion permeability Reflectivity Transmission efficiency Top if Example 1
(Oh oh) 10 0.5 81.89 3.45 78.45 9.29 95.80% 10 3 80.96 3.31 77.65 9.43 95.91% 10 5 77.27 2.13 75.14 10.48 97.24% 10 7 77.67 1.92 75.75 11.37 97.53% Example 2
(Ball / Ball) 10 0.5 88.56 4.87 83.70 8.05 94.51% 10 3 87.59 4.25 83.34 9.06 95.15% 10 5 72.31 1.41 70.90 16.66 98.05% 10 7 61.77 1.29 60.48 20.14 97.91% Example 3
(Ball / Oh) 10 0.5 84.92 4.58 80.35 8.30 94.62% 10 3 82.70 2.08 80.61 10.87 97.47% 10 5 75.62 4.38 71.24 8.69 94.21% 10 7 80.26 1.77 78.50 12.39 97.81% Example 4
(Oh / Ball) 10 0.5 85.77 3.28 82.48 9.41 96.16% 10 3 88.46 3.13 85.33 9.48 96.46% 10 5 78.47 1.40 77.07 15.28 98.22% 10 7 64.81 1.15 63.66 21.80 98.23%

diameter Total transmittance Straight Transmittance Dispersion permeability Reflectivity Transmission efficiency Top if Comparative Example 1 - - 78.79 76.12 2.67 3.70 3.39 Comparative Example 2
(Five/-) 0.5 - 77.23 72.95 4.29 4.29 5.55 3 - 77.86 25.34 52.52 8.75 67.45 5 - 79.23 7.99 71.23 8.73 89.90 7 - 78.51 3.64 74.87 8.87 95.36 10 - 77.48 3.54 73.94 9.24 95.43 15 - 77.87 3.89 73.98 8.79 95.00 20 - 78.20 5.80 72.41 8.51 92.60 Comparative Example 3
(-/Five) - 0.5 80.38 76.85 3.53 3.21 4.39 - 3 78.62 64.22 14.41 4.56 18.33 - 5 75.16 12.12 63.04 5.03 83.87 - 7 75.26 5.80 69.47 5.99 92.31 - 10 64.63 4.19 60.43 11.44 93.50 - 15 58.24 3.80 54.43 18.79 93.46 - 20 56.92 5.12 51.80 17.38 91.00 Comparative Example 4
(ball/-) 0.5 - 77.82 74.29 3.53 3.23 4.54 3 - 77.36 49.57 27.78 8.02 35.91 5 - 78.67 5.50 73.17 9.32 93.01 7 - 81.49 6.09 75.40 8.69 92.53 10 - 80.43 4.53 75.90 8.77 94.37 15 - 77.52 4.82 72.71 8.64 93.80 20 - 82.08 7.38 74.70 8.48 91.01 Comparative Example 5
(-/ball) - 0.5 78.79 73.67 5.12 3.00 6.50 - 3 80.33 60.95 19.38 3.74 24.13 - 5 69.01 5.40 63.62 4.77 92.19 - 7 60.98 5.40 55.58 11.87 91.14 - 10 55.38 3.53 51.85 18.04 93.63 - 15 55.07 4.06 51.01 17.87 92.63 - 20 54.32 6.94 47.38 22.85 87.22

As can be seen from Tables 1 and 2, the transparent electrode of the embodiment exhibited a higher transmittance efficiency, that is, a dispersion transmittance value than the total transmittance, compared to the transparent electrode of the comparative example. This is believed to be due to the structure of the microlens array on both sides.

The transparent electrode of the embodiment has a high dispersion transmittance value, and the optoelectronic device to which it is applied can exhibit excellent light absorption and current density due to an increased optical path. In addition, having a high transmission efficiency value, the optoelectronic device to which it is applied can have excellent light efficiency.

In addition, when the transparent electrode of the embodiment is applied to an organic solar cell, the light that is not absorbed by the light absorbing layer and transmitted is also reflected by the back electrode, and is double-reflected by the microlens array structure of the bottom and top surfaces of the transparent electrode, It can be absorbed by the scattering, light absorbing layer. Accordingly, when applied to an organic solar cell, the above-described effect may be further increased as compared to the transparent electrode of the comparative example having no microlens array structure on both surfaces or formed on only one surface.

More specifically, by comparison, most of the transparent electrodes of the Examples showed a transmission efficiency value of more than 95%, and in Examples 2 and 4, about 98% of the transparent electrodes having a microlens diameter of 5 or 7 μm on the bottom surface It showed a remarkably excellent transmission efficiency value.

In addition, in the case of a transparent electrode having a diameter of 0.5 or 3 µm of the microlens on the lower surface, a transmittance efficiency value of about 95% was shown, while a significantly higher total transmittance value was also exhibited.

In particular, in Examples 2 and 4, in the case of the transparent electrode having a diameter of 0.5 or 3 μm of the microlens of the lower surface, a transmission efficiency value of about 95% and a total transmittance value in the second half of 80 are exhibited, and the total transmittance value itself and the transmission efficiency All were excellent.

On the other hand, in Comparative Example 1 without both microlens structures, the transmission efficiency was very low, about 3%.

In addition, in the case of Comparative Examples 2 to 5 in which the microlens structure was formed on only one surface, the transmittance efficiency rarely exceeded 95%, and even when it exceeded, it exhibited a relatively low total transmittance value.

Claims (9)

(a) forming a first cured resin layer having an uneven structure on an upper surface by transfer and curing on a substrate,
(b) forming a release layer having a shape of the uneven structure on the first cured resin layer,
(c) forming a metal nanowire layer having the shape of the uneven structure on the release layer,
(d) forming a second cured resin layer on the metal nanowire layer, having a concavo-convex structure on the upper surface by transfer and curing, and impregnating the metal nanowire, and
(e) separating the second cured resin layer, having a concavo-convex structure on the upper and lower surfaces, and impregnating the metal nanowires to obtain a cured film, including, a method of manufacturing a transparent electrode. According to claim 1,
The (a) or (d) step, forming a curable resin layer,
Adhering a siloxane-based resin mold having an uneven structure to the curable resin layer,
Curing the curable resin layer, and
And removing the siloxane-based resin mold. According to claim 2,
The uneven structure of the siloxane resin mold is a microlens array structure, a method of manufacturing a transparent electrode. According to claim 3,
The method of manufacturing a transparent electrode having a diameter of each microlens constituting the microlens array structure of the siloxane resin mold in the step (a) is 0.1 to 10 μm. According to claim 3,
The method of manufacturing a transparent electrode having a diameter of each microlens constituting the microlens array structure of the siloxane-based resin mold in step (d) is 3 to 30 μm. A transparent electrode comprising a cured film, wherein the cured film has an uneven structure on the upper and lower surfaces, and is impregnated with metal nanowires. The method of claim 6,
The concavo-convex structure is a micro-lens array structure, a transparent electrode. The method of claim 7,
The diameter of each micro-lens forming the micro-lens array structure on the top surface of the cured film is 3 to 30 μm, a transparent electrode. The method of claim 7,
The diameter of each micro lens constituting the micro lens array structure on the lower surface of the cured film is 0.1 to 10 μm, transparent electrode.