KR102029343B1 - Metal network transparent electrode having enhanced invisibility, method of manufacturing the same - Google Patents

Abstract

The present invention provides a metal network transparent electrode having increased transparency and a manufacturing method thereof. According to an embodiment of the present invention, the metal network transparent electrode comprises: a metal nanomaterial core having a network structure; an oxidation layer arranged on the metal nanomaterial core; and a refractive index matching layer arranged on the oxidation layer.

Description

Metal network transparent electrode with enhanced invisibility, method of manufacturing the same

The technical idea of the present invention relates to a metal network transparent electrode having increased transparency, a manufacturing method thereof, and a heater including the same.

In order to replace the indium tin oxide used as the transparent electrode, a metal electrode having a mesh structure has been raised. However, when a strong external light is irradiated due to the light reflection and scattering phenomenon, which are physical properties of metals, light scattering and reflection are maximized by the net structure, thereby reducing the transparency and visibility of the net structure. There is a problem. This is because the dipoles inside the metal vibrate by light that is external electromagnetic waves, and the vibrations of these dipoles interfere with the progress of the light, causing reflection and scattering to occur. Accordingly, there is a need for a technique of suppressing reflection and scattering of light to increase the transparency of a transparent electrode formed of a metal.

European Patent No. EP 2151883 B

The technical problem of the present invention is to provide a transparent metal network transparent electrode and a method of manufacturing the same.

The technical problem to be achieved by the technical idea of the present invention is to provide a heater including a metal network transparent electrode with increased transparency and a manufacturing method thereof.

However, these problems are exemplary, and the technical idea of the present invention is not limited thereto.

Metal network transparent electrode according to the technical idea of the present invention for achieving the above technical problem, the metal nanomaterial core having a network structure; An oxide layer disposed on the metal nanomaterial core; And a refractive index matching layer disposed on the oxide layer.

In some embodiments of the present invention, the metal nanomaterial core is silver (Ag), gold (Au), platinum (Pt), copper (Cu), chromium (Cr), gallium (Ga), nickel (Ni) Or an alloy thereof.

In some embodiments of the present invention, the oxide layer may be formed of an oxide of the metal nanomaterial core.

In some embodiments of the present invention, the oxide layer may be formed through a deposition method.

In some embodiments of the present invention, the oxide layer may include Ag ₂ O, Fe ₂ O ₃ , CuO, ITO, IGZO, or ZnO.

In some embodiments of the present invention, the refractive index matching layer may include silicon oxide or a transparent polymer.

In some embodiments of the present invention, the refractive index matching layer may have a refractive index in the range of 1 to 6.

In some embodiments of the present invention, the metal nanomaterial core and the oxide layer may have the same refractive index.

In some embodiments of the present invention, the network structure may be a random network structure.

In some embodiments of the present invention, the metal nanomaterial core may have a diameter in the range of 100 nm to 20000 nm.

In some embodiments of the present invention, the oxide layer may have a thickness in the range of 5 nm to 1000 nm.

In some embodiments of the present invention, the method may further include a cavity region disposed between the metal nanomaterial core and the oxide layer.

According to an aspect of the present disclosure, there is provided a metal network transparent electrode comprising: a metal core formed of a metal material having a network structure; An oxide layer disposed on the metal core; And a refractive index matching layer disposed on the oxide layer.

According to an aspect of the present invention, there is provided a method of manufacturing a metal network transparent electrode, comprising: forming a metal network by electrospinning a metal nanomaterial; Oxidizing a surface of the metal network to form an oxide layer; And forming a refractive index matching layer on the oxide layer; It includes.

In some embodiments of the present disclosure, the forming of the oxide layer may be performed by irradiating the ozone with the metal network.

In some embodiments of the present disclosure, the forming of the refractive index matching layer may be performed by using a Meyer rod coating method.

According to another aspect of the present invention, there is provided a method of manufacturing a metal network transparent electrode, the method comprising: forming a network by electrospinning a polymer; Depositing a metal nanomaterial on the network to form a metal network; Transferring the metal network to a substrate; Removing the polymer; Oxidizing a surface of the metal network to form an oxide layer; And forming a refractive index matching layer on the oxide layer.

In some embodiments of the invention, the polymer comprises polyvinylpyrrolidone, and the removing of the polymer may be performed using ethanol.

According to an aspect of the present invention, a heater includes: a metal nanomaterial core having a network structure; An oxide layer disposed on the metal nanomaterial core; And a refractive index matching layer disposed on the oxide layer.

Method of manufacturing a heater according to the technical idea of the present invention for achieving the above technical problem, the metal nanomaterial core having a network structure; An oxide layer disposed on the metal nanomaterial core; Preparing a nanofiber consisting of a metal network transparent electrode comprising a; refractive index matching layer disposed on the oxide layer; Forming conductive pads at both ends of the nanofibers; Forming a blocking layer on the conductive pad; Surface oxidation of the nanofibers; Removing the barrier layer; And forming a refractive index matching layer on the nanofibers.

As the metal network transparent electrode according to the spirit of the present invention has a structure of a metal, an oxide and a refractive index matching layer, the metal having a unit structure can maintain a very large scattering cross section induced by local surface plasmons, When used as transparent electrodes in displays, touchscreens, and smart windows, adverse effects due to low transparency can be prevented from occurring. Here, it can provide a broadband optical clocking strategy for a network of mesoscopic metal wires with diameters from submicrometers to micrometers, and can be used for the manufacture and application of high-transparent metal internal transparent electrodes. . Electrospinning is used to form silver (Ag) interconnects of 300 nm to 1800 nm in diameter, and a core / shell heterostructure of Ag / Ag ₂ O is formed using an easy surface oxidation process. Absorbent Ag ₂ O shells coated with a dielectric sheath can release electrical multipole moments in the silver (Ag) wiring, thereby rapidly suppressing plasmon-mediated scattering in the entire visible light spectrum, Ag) Make the wiring invisible. Along with the effect of transparency, the transmittance of the Ag / Ag ₂ O wiring is considerably improved compared to silver (Ag) wiring, although an absorbent Ag ₂ O shell is formed. As an application, transparent silver (Ag) wiring can be used as a high transparency, high transmittance, and high speed defrosting device in automotive glass. Through the developed technology, it is possible to maximize the practicality of the transparent electrode by reducing the light scattering and reflection degree of the transparent electrode having the metal-based net structure in the environment such as strong light (daytime sunlight).

The effects of the present invention described above have been described by way of example, and the scope of the present invention is not limited by these effects.

1 is a conceptual diagram and simulation results showing the optical characteristics of the metal network transparent electrode according to an embodiment of the present invention.
2 illustrates a method of manufacturing a metal network transparent electrode according to an embodiment of the present invention.
3 illustrates a method of manufacturing a metal network transparent electrode according to an embodiment of the present invention.
Figure 4 shows the characteristics of the silver (Ag) nanofibers formed by the method of manufacturing a metal network transparent electrode according to an embodiment of the present invention.
5 is a graph showing the transmittance and sheet resistance according to the change in diameter of the metal network transparent electrode according to an embodiment of the present invention.
6 is a graph showing an optoelectronic spectroscopy spectrum of a metal network transparent electrode according to an embodiment of the present invention.
FIG. 7 illustrates a change in diameter according to ultraviolet ozone irradiation of a metal network transparent electrode according to an exemplary embodiment of the present invention.
8 is a photograph showing transparency of a metal network transparent electrode according to an embodiment of the present invention.
9 illustrates an electromagnetic simulation result of the metal network transparent electrode according to the exemplary embodiment of the present invention.
10 is a graph illustrating haze of a metal network transparent electrode according to an embodiment of the present invention.
11 is a graph showing the characteristics of a metal network transparent electrode according to an embodiment of the present invention.
12 are dark field micrographs of a metal network transparent electrode according to an embodiment of the present invention.
FIG. 13 illustrates a backscatter distribution of a metal network transparent electrode according to an embodiment of the present invention. FIG.
14 is a view showing a diameter change of ultraviolet ray ozone irradiation of a metal network transparent electrode according to an embodiment of the present invention.
15 illustrates a backscatter distribution of a metal network transparent electrode according to an embodiment of the present invention.
16 illustrates a forward scattering distribution of a metal network transparent electrode according to an embodiment of the present invention.
17 shows simulation results for optical characteristics under a lateral electric field of a metal network transparent electrode according to an embodiment of the present invention.
FIG. 18 illustrates simulation results of optical characteristics under a lateral magnetic field of a metal network transparent electrode according to an exemplary embodiment of the present disclosure.
19 is a simulation result showing the effect of the oxide layer of the metal network transparent electrode according to an embodiment of the present invention.
20 illustrates a method of manufacturing a heater constructed of a metal network transparent electrode according to an embodiment of the present invention.
21 illustrates exothermic experiment results of a heater constructed of a metal network transparent electrode according to an embodiment of the present invention.
22 illustrates heat transfer test results of the metal network transparent electrode according to the exemplary embodiment of the present invention.
FIG. 23 illustrates defrost test results of a heater configured of a metal network transparent electrode according to an exemplary embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Embodiments of the present invention are provided to more fully explain the technical idea of the present invention to those skilled in the art, and the following embodiments may be modified in many different forms, and The scope of the technical idea is not limited to the following examples. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the inventive concept to those skilled in the art. In the present specification, the same reference numerals mean the same elements. Furthermore, various elements and regions in the drawings are schematically drawn. Therefore, the technical idea of the present invention is not limited by the relative size or the distance drawn in the accompanying drawings.

Metals with negative permittivity epsilon can be used as broadband high reflection mirrors at optical frequencies. More interestingly, metals having a nanometer to micrometer sized unit structure can induce local surface plasmon resonances at certain wavelengths, thus freeing the radiated energy of subwavelength-volume electromagnetic modes. To energy or vice versa. This phenomenon is called plasmon scattering. The concept of plasmon scattering was used to improve the performance of a wide range of optical devices including optical sensors, lithography systems, solar cells, and light emitting diodes. However, when using metal wiring as a transparent electrode in imaging applications such as displays, touchscreens, and smart windows, unwanted conditions can often be caused by plasmon mediated scattering.

1 is a conceptual diagram and simulation results showing the optical characteristics of the metal network transparent electrode according to an embodiment of the present invention.

Referring to FIG. 1, (a) is a case where scattering by a metal is not controlled, and the dipoles inside the metal are vibrated by light, which is external electromagnetic waves, and the progress of light is disturbed by the vibration of the dipoles. This happens. The electric field profile of bare silver (Ag) nanofibers due to such reflection and scattering is shown.

On the other hand, Figure 1 (b) is a case where the scattering is controlled, by forming an oxide layer having a dipole opposite to the dipole inside the metal, it is possible to drastically reduce the scattering and reflection of light by the metal dipole. Accordingly, since the transmittance is improved and scattering degree is reduced, the practicality of the metal network transparent electrode can be maximized. The electric field profile of Ag / Ag ₂ O nanofibers due to this scattering reduction is shown on the right.

More specifically, as shown in Fig. 1A, the metal wires can be clearly observed by the naked eye, thereby reducing the transparency of the visibility. Thus, periodic grid metal wires, nanowires (NW) containing metals, nanofibers (NF), or nanotroughs (NAnotroughs, NT) have the advantage of high transmittance to sheet resistance. Nevertheless, the reduced transparency may make it difficult to expand use. Thus, there is a need for economical and viable technology development that makes two-dimensional metal networks invisible over the entire visible light spectrum while maintaining low sheet resistance with high transmission.

To date, optical clocking prepared from reasonably designed metamaterials and metasurfaces has been of considerable interest for various industrial and military purposes, and there are studies as follows. For example, Zhang's research group has published a metasurface layer using phase delaying Au nanorods that hide information on the curvature of any shape surface. The Cocabas research group has published graphene-based adjustable absorbers that operate at microwave frequencies to avoid radar tracking. The Brongersma research group has published a 50 nm diameter silicon nanowire photodetector that reduces scattering by coating a thin conformal gold (Au) shell less than 20 nm. These studies are based on techniques for controlling the transmission wave vectors, absorption, or scattering of incident light. The developed optical clocking has successfully started a new era of optical devices using nanomaterials, but has limitations such as operating only within a limited range for wavelengths and specific polarizations. In addition, several studies on broadband optical clocking based on the principles of transformed optics have been published. However, for the implementation of conversion optics, macroscopic and complex optical designs are required and may not be appropriate for practical devices. In addition, for the implementation of optoelectronic devices, whether the clocking structure preserves device performance is an ongoing issue. The transparent silicon nanowire photodetector described above can compensate for absorption efficiency by preservation of a thin gold (Au) shell as a clocking structure.

The present invention discloses an easy cloaking strategy for making the mesoscopic metal wiring invisible for the entire visible spectrum, i.e. from sub-wavelength to wavelength, for two orthogonal polarizations. Metal structures generally have wide electrical multipole moments and therefore cannot be easily clocked. In the case of having the clocking for the transparency, the metal wiring can function as a very high figure of merit of the transparent electrode, and there is a possibility of maintaining the same transparency as that of a pristine glass substrate. In addition, clearing clocking can be generalized for a wide range of sizes from hundreds of nanometers to several micrometers in metal wiring and other shapes such as solid nanofibers and tubular nanotropes. As an application example, it can be applied to high transparency, high transmittance, and high speed defrosting apparatus in automotive glass using a network of transparent metal wires.

2 illustrates a method of manufacturing a metal network transparent electrode according to an embodiment of the present invention.

Referring to Figure 2, (a) is a schematic diagram of the manufacturing method, (b) is a scanning electron microscope cross-sectional photograph at each step. According to an aspect of the inventive concept, a method of manufacturing a metal network transparent electrode may include forming a metal network by electrospinning a metal nanomaterial, forming an oxide layer by oxidizing a surface of the metal network, and matching a refractive index on the oxide layer. Forming an index matching layer (IML).

3 illustrates a method of manufacturing a metal network transparent electrode according to an embodiment of the present invention.

Referring to Figure 3, (a) is a schematic diagram of the manufacturing method, (b) is a scanning electron microscope cross-sectional photograph at each step. In the method of manufacturing a metal network transparent electrode according to the technical concept of the present invention, forming a network by electrospinning a polymer, and forming a metal network by depositing a metal nanomaterial such as silver (Ag) on the network Transferring the metal network to a substrate, removing the polymer, oxidizing the surface of the metal network to form an oxide layer, and forming a refractive index matching layer on the oxide layer.

Hereinafter, an embodiment of the manufacturing method of the metal network transparent electrode will be described in detail. In this embodiment, the case where silver (Ag) is used as a metal is demonstrated.

Fabrication of random (Ag) nanofibers with network structure

A method of preparing Ag nanofibers of a random network structure is as described with reference to FIG. 2. Electrospinning was used to electrospin a suspension containing silver (Ag) nanoparticles as ink directly onto a glass substrate to prepare silver (Ag) nanofibers of continuously long random network structures. The average diameter of the silver (Ag) nanoparticles used was 40 ± 5 nm. The solvent of the suspension contained ethylene glycol in 50% composition.

In the electrospinning apparatus, an electric field of 7.6 kV / m was applied between the end of the nozzle and the ground. The inside diameter of the nozzle was 0.33 mm and the outside diameter was 0.64 mm. The height for electrospinning was 15 cm, the environmental temperature was 17 ° C., and the relative humidity was 4%. By varying the flow rate of silver nanoparticles in the range of 0.2 ml / hr to 1.8 ml / hr, silver (Ag) nanofiber diameters were controlled in the range of 338 ± 33 nm to 1792 ± 167 nm. Low density silver (Ag) nanofiber networks for transparent electrodes formed by electrospinning at a flow rate of 0.2 ml / hr showed significantly lower sheet resistance of 5.4 ± 0.9 per Ω sq and transmittance of 96%. The electrospun silver (Ag) nanofibers were uniformly distributed on the substrate without the silver (Ag) nanofibers being agglomerated or laminated. It can be seen that the diameter of the silver (Ag) nanofibers can be easily adjusted by controlling the flow rate of the silver (Ag) nanoparticle ink. See the references for other details on how to make electrospun metal nanofiber networks.

The electrospun nanofibers were then heat treated at 150 ° C. for 30 minutes in air with a relative humidity of 25% or less. The substrate used was 1.5 mm thick glass (Matsunami Glass Ind. Ltd, Japan), and the size was 4 × 3.5 cm ² . By the heat treatment, silver (Ag) nanoparticles were aggregated and thus converted into conductive silver (Ag) nanofibers.

<Preparation of Transparent Ag / Ag ₂ O Nanofibers / Refractive Index Matching Layer>

Ag (Ag) nanofibers prepared as described above were oxidized, and then a refractive index matching layer was coated on the oxidized silver (Ag) nanofibers to form an Ag / Ag ₂ O nanofibers / refractive index matching layer.

The oxidation process was performed using an ultraviolet ozone treatment system (AC-6, AHTECH LTS, Korea). Random nanostructured silver (Ag) nanofibers were placed 4 cm away from the mercury grid lamp and exposed for 10 minutes to oxidize the surface of the silver nanofibers.

A refractive index matching layer was formed on the oxidized silver nanofibers using the Meyer rod coating method. Specifically, a refractive index matching layer solution (SOH 103H, ChangSungNanoTech., Korea) is applied onto oxidized silver (Ag) nanofibers, followed by coating the solution with Meyer Rod (# 7, RD specialist Inc.). do. During the Mayer rod coating process, the thickness of the final layer is determined by the diameter of the rod used and the distance between the rod and the rod. The coated layer was heat treated at 65 ° C. for 5 minutes in air. The thickness of the refractive index matching layer formed was generally 7 m.

Fabrication of Random Nanostructured Silver Nanotropes

The method of preparing the silver (Ag) nanotrope of the random network structure is as described with reference to FIG. 3. Polyvinylpyrrolidone (PVP) solution was electrospun to form freestanding polymer fibers. The polyvinylpyrrolidone solution was prepared by dissolving PVP (Mw = 1,300,000 g / mol) (Sigma-Aldrich) in methanol at a concentration of 11 wt%. The flow rate of the polymer solution was adjusted to 0.3 ml / hr, a voltage of 9.2 kV was applied to a 0.64 mm diameter nozzle, and the freestanding PVP fibers were collected in an aluminum frame. Metal nanotrots were prepared by thermal evaporation of silver (Ag). This thermal evaporation deposited a layer of 100 nm thick silver (Ag) on the freestanding PVP fibers. Random (Ag) nanotropes of random network structure were transferred onto glass substrates, and then PVP was removed by immersion in ethanol in air with a relative humidity of 25% or less. See other references for other details of methods of making electrospun metal nanotrope networks. Then, if necessary, the oxidation and refractive index matching layer coating was performed on the silver (Ag) nanotrope as described above.

<Production of heaters composed of transparent electrodes>

In order to make a heater composed of Ag / Ag ₂ O nanofibers / refractive matching layer, additional contact pads are needed. PDMS shadow mask (sylgard-184, Sigma Aldrich) was used to prevent oxidation of both ends of silver (Ag) nanofibers of random network structure. Subsequently, a coating process of the refractive index matching layer was performed in the region of Ag / Ag ₂ O nanofibers. Silver (Ag) epoxy (ELCOAT A-200, CANS, Japan) pads functioning as contact pads at both ends of the transparent electrodes were formed, and both ends were connected to a power source.

As a comparative example, in the case of a heater composed of silver (Ag) nanowires, a silver (Ag) nanowire solution (Sigma Aldrich, 7440-22-4) was formed by spin coating on a glass substrate for 30 seconds at 500 rpm. It was. Here, the average diameter of silver (Ag) nanowires was 115 ± 2 nm and the length was 40 ± 2 μm.

As another comparative example, in the case of a heater composed of indium tin oxide, a 120 nm thick layer of indium tin oxide was deposited on a glass substrate using a radio frequency sputter system (SRN-120, SORONA, Korea).

The average transmittances of the silver (Ag) nanowires and the indium tin oxide layer were about 94% at a wavelength of 532 nm with respect to the visible light spectrum. The sheet resistances of the Ag / Ag ₂ O nanofibers / refractive index matching layer, silver (Ag) nanowires, and indium tin oxide layer were 1.9 Ω / cm- ² , 15 Ω / cm- ² , and 60 Ω / cm-, respectively. ² was. Copper wires were contacted at both ends of each heater with silver (Ag) epoxy (ELCOAT A-200, CANS, Japan) and then treated at 25 ° C. for 10 minutes in air with a relative humidity of 25% or less.

<Thermal radiation experiment>

For the thermal radiation test, Ag / Ag ₂ O nanofibers / refractive index matching layer, silver (Ag) nanowires, and 120 nm thick indium tin oxide electrodes were prepared on the polyimide layer in the same manner as in the heater manufacturing step. It was. To minimize heat transfer through the substrate, a thin, transparent polyimide layer (Mitsubishi Corp., Japan) was used as the substrate for the three heaters in place of 1.5 mm thick thick glass. The polyimide layer had a characteristic of 5 × 50 mm ² size, 25 μm thickness, T _g of 302 ° C. All heaters showed the same average optical transmission of 94% for the visible light spectrum. One end of all samples was horizontally attached to a heating plate (EC-1200NP, AS ONE Corp., Japan) using thermal grease (Samwon Chemical, Korea). Also, the other end of all the samples was attached to the cold plate. The temperature of the heating plate was 140 ° C., and heat radiation was measured by a thermal infrared camera.

Defrost experiment

For the defrost test, Ag / Ag ₂ O nanofibers / refractive index matching layer, silver (Ag) nanowires respectively disposed on a glass substrate (Matsunami Glass Ind. Ltd, Japan) in the same manner as the heater manufacturing method. , And indium tin oxide were prepared. All electrodes were stored for 60 minutes in the refrigerator, forming frost on the entire surface. To match the car model, the samples were each 100 × 50 mm ^{2 in} size.

Characterization of Transparent Electrodes

In order to analyze the surface properties of silver (Ag) nanofibers, scanning electron microscope (S4600, Hitachi, Tokyo, Japan), optical microscope (BX53, Olympus, Tokyo, Japan), and high resolution transmission electron microscope (JEM-2100F, JEOL) , Tokyo, Japan). The atomic fraction of silver (Ag) nanofibers was analyzed using X-ray photoelectron spectroscopy (XPS) (ESCALAB 250XI, Thermo Fisher Scientific, USA).

In order to analyze the electrical characteristics, four and two needle methods were used to measure sheet resistance and electrical resistance using a probe station having a semiconductor parameter analyzer (Keithley 4200-SCS). To analyze the sheet resistance of Ag / Ag ₂ O nanofibers, 100 nm thick gold pads were deposited using thermal evaporation. The sheet resistance was calculated using the change in electrical resistance of each sample.

To analyze the optical properties, optical transmittance was measured using an ultraviolet to near infrared spectroscopy system (Cary 5000 UV-Vis-NIR, Agilent, USA) with diffuse reflectance accessories. The transmittance | permeability of a glass substrate is used as a reference value.

In order to analyze the thermal characteristics, DC bias was applied using a power source (Keithley 2260B-30-72, USA). The temperature was measured using a long wavelength infrared (LWIR) camera (T650sc, FLIR Systems, USA). The temperature distribution was analyzed using FLIR Research IR software (Research IR Max, FLIR Systems).

<Scattering distribution analysis>

Scattering distributions were measured using a far field scanner with a photodetector and an incident light source. The spectrometer (USB4000, Ocean Optics) was programmed to rotate along the direction of azimuth (φ) and polarity (θ) with a step size of 2 degrees. Red light emitting semiconductor lasers (λ = 660 nm), green light emitting semiconductor lasers (λ = 532 nm), or blue light emitting semiconductor lasers (λ = 450 nm) (Three Color, Korea), or broadband (λ = 450-2500 nm) Supercontinental lasers (Super K Compact, NKT Optics, USA) were used as incident light sources. For the measurement of backscattering distributions, the angle of incidence was set at 60 degrees with respect to the vertical line. The ranges of the measured polar (θ) and azimuth (φ) angles were set to ± 28 degrees and ± 40 degrees, respectively. For the measurement of forward scattering distributions, the angle of incidence was set perpendicular to the samples. The range of polar and azimuth angles was set to ± 28 degrees and ± 180 degrees, respectively.

Electromagnetic simulation analysis

All numerical simulations were performed using the FDTD program. FDTD simulations were used to obtain scattering efficiency of various Ag / Ag ₂ O nanofibers. To calculate wavelength resolved scattering cross sections, electrical and magnetic scattering fields were obtained using a total-field scattered-field method. The normal incident plane wave had an incremental step of 5 nm and scanned the wavelength range between 450 nm and 700 nm. The scattering cross section obtained is then divided by the total projected area (silver (Ag) core + Ag ₂ O shell) to determine the scattering efficiency. The spatial resolution was set at 5 nm for the in-plane axes. For cylindrical axes, periodic boundary conditions were applied.

Figure 4 shows the characteristics of the silver (Ag) nanofibers formed by the method of manufacturing a metal network transparent electrode according to an embodiment of the present invention.

4, (a) is a graph showing the relationship between the diameter of the silver (Ag) nanofibers and the solution flow rate, (b) is a scanning electron micrograph showing the silver (Ag) nanofibers of a random network structure; (c) Magnified scanning electron micrographs of single silver (Ag) nanofibers with different diameters.

Table 1 shows the characteristics of silver (Ag) nanofibers formed by the method of manufacturing a metal network transparent electrode according to an embodiment of the present invention.

Target diameter
(nm) Measuring diameter Area of nanofiber
(mm ² ) Unit area
(mm ² ) Nano fiber
Area fraction
(%) Unit area
For
Nano Fiber
Length
(mm / mm ² ) 1800 1792 ± 167 13.9 x 10 ^-3 0.195 7.15 39.9 ± 3.7 1100 1075 ± 103 8.4 x 10 ^-3 0.195 4.33 40.3 ± 4.4 750 751 ± 61 5.8 x 10 ^-3 0.195 3.02 40.2 ± 3.4 600 609 ± 50 4.8 x 10 ^-3 0.195 2.49 40.8 ± 3.4 300 338 ± 33 2.7 x 10 ^-3 0.195 1.37 40.5 ± 3.9

Referring to FIG. 4 and Table 1, silver (Ag) nanofibers having diameters D in the range of 300 nm to 1800 nm were formed. In addition, it can be seen that the diameter of the silver (Ag) nanofibers increases as the solution flow rate increases in (a) of FIG. 4, and this tendency can be confirmed by the photographs of (b) and (c). have. Thus, it can be seen that the electrospinning method can form relatively transparent electrodes composed of metal wires potentially having a large area of 1 m ² or more. The very long silver (Ag) nanofibers produced can minimize the number of interconnections between the nanofibers and thus reduce sheet resistance despite small area fractions, and these geometric elements can provide high transmittance.

5 is a graph showing the transmittance and sheet resistance according to the change in diameter of the metal network transparent electrode according to an embodiment of the present invention.

Referring to FIG. 5, "metal mesh" refers to a mesh electrode made of silver (Ag) nanofibers, and "metal mesh + oxide layer" is a case where an oxide layer is formed on the silver (Ag) nanofibers, and "metal" mesh + oxide layer + index matching layer "is a case where an oxide layer is formed and a refractive index matching layer is formed.

As the diameter is increased, sheet resistivity decreases, and silver nanofibers without an oxide layer exhibit the lowest sheet resistance. However, as the diameter is increased, it can be seen that the difference in sheet resistance is significantly reduced. In addition, there was little change in sheet resistance as the refractive index matching layer was added. For reference, the thickness of the oxidized samples was equally controlled to 150 nm.

It can be seen that the transmission is improved at all diameters for wavelength 550 nm light. In addition, the permeability was higher in the case of having an oxide layer compared to the silver (Ag) nanofibers without the oxide layer, and the increase in permeability was increased as the diameter was increased. In particular, in the case of further having a refractive index matching layer, it increased from 300 nm to 900 nm, indicating a value close to 100%. Above 900 nm, the case of having an oxide layer and the case of further having a refractive index matching layer showed almost close values.

Although silver nanofibers function as higher performance index transparent electrodes compared to silver nanowires with conductive oxide layers, conductive polymers, graphene, metal grids, and even random network structures, As shown in FIG. 4, large scattering induced by individual silver (Ag) nanofibers has the limit of decreasing the transparency of visibility through the substrate. Ag / oxide cores / covered with an index-matching layer (IML), as shown in FIGS. 2 and 3, to increase the transmission of silver (Ag) nanofibers of random network structure through the glass substrate. Peel nanofibers may be proposed. The refractive index matching layer may be composed of SiO ₂ and a polymer binder, and may have an optical thickness of, for example, 7 μm.

6 is a graph showing an optoelectronic spectroscopy spectrum of a metal network transparent electrode according to an embodiment of the present invention.

Referring to FIG. 6, (a) is a case of silver (Ag) 3d peak of silver (Ag) nanofibers before oxidation, and (b) is a case of silver (Ag) 3d peak of silver (Ag) nanofibers after oxidation. If it is. Almost no silver (Ag) oxide exists before oxidation, but after the oxidation, silver (Ag) and silver (Ag) oxide exist. In addition, the silver (Ag) oxide is analyzed to consist mostly of Ag ₂ O. Such Ag ₂ O was formed on the surface of the silver (Ag) core by irradiation with ultraviolet ozone, and can also be confirmed by scanning electron micrograph of FIG. The Ag ₂ O material is known to have a large extinction coefficient k over the entire visible light spectrum.

In general, a dielectric shell, such as an oxide coated on metal or semiconductor nanostructures, can have a leverage effect to amplify the optical antenna effect (ie, scattering cross section). Additionally, as the metal and dielectric have opposite signs of dielectric, such as ε <0 and dielectric has ε> 0, the nanostructure of the metal core / dielectric shell or the nanostructure of the dielectric core / metal shell decreases. The scattered cross section can be maintained. Especially for mesoscopic objects that exceed the quasistatic approximation related to the present invention, the design rules established by previous theoretical studies suggest that low dielectric constant shells and high dielectric constant background media are preferred to remove high dimensional scattering coefficients. It is displayed. These conditions are in good agreement with the use of high absorbing Ag ₂ O shells and dielectric refractive index matching layers (n = 1.5). The surface of the grown silver nanofibers and the subsequent Ag ₂ O shell is quite rough. Therefore, the refractive index matching layer formed on the oxide layer can alleviate such rough surface, thereby further reducing scattering which may be caused by the rough surface.

FIG. 7 illustrates a change in diameter according to ultraviolet ozone irradiation of a metal network transparent electrode according to an exemplary embodiment of the present invention.

Referring to FIG. 7, (a) is a graph showing a change in diameter, and (b) is a scanning electron micrograph and a schematic diagram at 0 minutes, 10 minutes, and 60 minutes. As the ultraviolet ozone irradiation time increases, the diameter of the silver (Ag) core having a diameter of 400 nm initially decreases, and the thickness of the Ag ₂ O shell increases. In addition, a thin void void interposed between the silver (Ag) core and the Ag ₂ O shell by oxidation is observed. This cavity region is known as the Kirkendall effect because the diffusion rate of oxygen atoms from the shell is relatively small compared to the diffusion rate of silver (Ag) atoms from the core. The total diameter tends to increase, with an initial increase of up to 15 minutes due to the formation of Ag ₂ O shells and cavity areas, and later increases after 15 minutes due to the formation of cavity areas.

8 is a photograph showing transparency of a metal network transparent electrode according to an embodiment of the present invention.

Referring to FIG. 8, "metal mesh" refers to a mesh electrode made of silver (Ag) nanofibers, and "metal mesh + oxide layer" is a case where an oxide layer is formed on the silver (Ag) nanofibers, and "metal" mesh + oxide layer + index matching layer "is a case where an oxide layer is formed and a refractive index matching layer is formed. Ag / Ag ₂ O nanofibers (300 nm in diameter, 150 nm in thickness) of random network structure are covered with a refractive index matching layer. In the case of having an oxide layer and a refractive index matching layer, it exhibited significantly increased transparency through the glass substrate in conventional room light and focused high intensity light of 251 mW / cm ² . While value of the oxidation process and the refractive index matching layer coating process, the level of transparency continues to improve, which means that the silver (Ag) nanofibers become invisible to the naked eye. In particular, thin cavity regions in oxidized silver (Ag) nanofibers have only a secondary effect on the level of transparency through the glass substrate.

9 illustrates an electromagnetic simulation result of the metal network transparent electrode according to the exemplary embodiment of the present invention.

Referring to FIG. 9, (a) is an electromagnetic simulation model, (b) is a transverse-electrical (TE) polarization behavior, and (c) is a transverse-magnetic (TM) polarization behavior. Indicates. The diameter of the silver (Ag) core was 800 nm and the thickness of the outer Ag ₂ O shell oxide shell was 160 nm. The refractive index of the background medium was 1.5 and was the same as the refractive index matching layer used in the experiment. In both the transverse (TE) polarization behavior and the transverse magnetic (TM) polarization behavior, the silver (Ag) nanofibers after oxidation show lower scattering efficiency compared to the silver (Ag) nanofibers before oxidation, thus increasing transparency. . In addition, it can be seen that as the thickness d of the cavity region is increased, the efficiency of the acid is further lowered, thereby further increasing transparency. This result is consistent with the result of FIG. 7.

10 is a graph illustrating haze of a metal network transparent electrode according to an embodiment of the present invention.

Referring to FIG. 10, a wide range of initial silver (Ag) nanofiber diameters (D) ranging from 300 nm to 1800 nm to demonstrate that clocked Ag / Ag ₂ O nanofibers preserve performance as transparent electrodes. Transmittance (T), sheet resistance (R) for three samples of bare silver (Ag) nanofibers, Ag / Ag ₂ O nanofibers, and Ag / Ag ₂ O nanofibers / refractive index matching layer _s ) and haze were reviewed. The area fractions of silver (Ag) nanofibers for all samples were initially the same for each silver (Ag) nanofiber diameter. Oxidized samples had a 150 nm thick Ag ₂ O shell. Here, the wavelength of incident light was 550 nm.

From these results, bare silver (Ag) nanofibers have a high figure of merit for a full range of silver nanofiber diameters, for example T> 92% and R _s <8.6 μs / sq. Indicated. More importantly, the clocked samples, ie in the case of Ag / Ag ₂ O / index matched layers, have an absorbent Ag ₂ O shell, but bare silver (Ag) nanofibers It has been shown to have higher transmittance and lower haze in comparison. This improved transmission is due in part to the shrinkage of the silver (Ag) core. However, comparing the transmittances of the Ag / Ag ₂ O nanofibers before and after having the refractive index matching layer, the improvement in the transmittance is mainly attributed to the clarification phenomenon by the optical loss in the Ag ₂ O shell is completely compensated. Although the Ag ₂ O shell increases R _s due to the relatively low carrier density, the clocked samples have a high figure of merit as a transparent electrode. Silver (Ag) nanofiber diameter of 750 nm had T = 99% and R _s = 4.8 ± 1.1 μs / sq.

11 is a graph showing the characteristics of a metal network transparent electrode according to an embodiment of the present invention.

Referring to FIG. 11, (a) is a graph showing transmittance, and (b) is a graph showing haze. In the refractive index adjusting layer covered by a random network, Ag / Ag ₂ O nano trough (NT) of the structure are similar to the results with the Ag / Ag ₂ O nanofiber of the random network structure was observed. That is, it showed higher transparency and improved transmittance as compared to bare nanotropes. These results indicate that the mesoscopic metal wiring is hidden from view by the clocking effect as the absorbing conformal shell and dielectric cover are introduced.

12 are dark field micrographs of a metal network transparent electrode according to an embodiment of the present invention.

Referring to FIG. 12, "Ag NFs" is for bare silver (Ag) nanofibers, "Ag / Ag ₂ O NFs" is for Ag / Ag ₂ O nanofibers with an oxide layer formed thereon, and "Ag / Ag ₂ O NFs / IML "is a case where an oxide layer and a refractive index matching layer are formed. To illustrate the observed clarification principle, optical photographs were obtained using a dark field microscope with a magnification of 100 times. In the case of including the oxide layer, the thickness of the AgO ₂ shell was 150 nm. From the micrographs, submicrometer-sized and micrometer-sized silver nanofibers are gradually blurred in the oxidation step and the refractive index matching layer formation, thus the silver nanofibers are in dark field micrographs. It is almost invisible, meaning backscatter is suppressed.

FIG. 13 illustrates a backscatter distribution of a metal network transparent electrode according to an embodiment of the present invention. FIG.

Referring to FIG. 13, (a) is a schematic diagram of a backscatter measuring device, (b) is a backscattering distribution at 300 nm diameter, (c) is a backscattering distribution at 750 nm diameter, and (d) Backscatter distribution at 1800 nm diameter.

Referring to FIG. 13A, the level of backscattering is precisely measured in the measuring device, and for this purpose, the photodetector is programmed to move in the direction of polarity (θ) and azimuthal (φ). For wideband transparency analysis of the entire visible light spectrum, a blue light emitting laser of 450 nm wavelength, a green light emitting laser of 532 nm wavelength, and a red light emitting laser of 660 nm wavelength were used as incident light sources, respectively. The polarization of the incident light in the construction of the random network structure was not important. The incident angle was set at 60 degrees with respect to the specimen.

Referring to (b), (c) and (d) of FIG. 13, it was confirmed that the reflectivity continued to decrease as the oxide layer and the refractive index matching layer were formed regardless of the size of the mesh. Two white dashed lines represent angular boundaries of ± 40 degrees. In addition, the oxide layers all had a thickness of 150 nm. The measured backscatter distributions showed two factors related to the clearing. First, for fixed silver (Ag) nanofiber diameters and light wavelengths, the scattering distribution became localized to a significant level after each manufacturing step. The final clocked samples behaved as fully specular surfaces specified by the scattering distribution distributed as dots. Second, this broadband clearing was observed for all diameters considered, namely 300 nm, 750 nm, and 1800 nm, although the scattering level slightly increased as the silver (Ag) nanofiber diameter increased. Thus, the above-described clocking strategy of suppressing scattering to hide mesoscopic metal wiring is analyzed to be appropriate for a wide range of wiring diameters and light wavelengths.

14 is a view showing a diameter change of ultraviolet ray ozone irradiation of a metal network transparent electrode according to an embodiment of the present invention.

Referring to FIG. 14, (a) is a graph showing a change in diameter, and (b) is a scanning electron micrograph at 0 to 10 minutes. In addition, the silver (Ag) core initially has a diameter of 1700 nm.

Referring to FIG. 14A, as the ultraviolet ozone irradiation time increases, the diameter of the silver (Ag) core decreases and the thickness of the Ag ₂ O shell increases. This shows the same tendency as the result of FIG. However, unlike the 400 nm initial diameter of FIG. 7, for larger 1700 nm diameters, a decrease in silver (Ag) cores, an increase in Ag ₂ O shell, and an increase in cavity area tend to be gradual. As mentioned above, the formation of Ag ₂ O shells occurs with a decrease in the diameter of the silver (Ag) core. The clarification is secondary to the reduction of the silver (Ag) core. Thus, samples of silver (Ag) nanofibers with a diameter of 1800 nm were prepared, and the thickness of the Ag ₂ O shell was gradually changed from 0 nm to 150 nm, thereby relatively reducing the problem of shrinkage of the silver (Ag) core. Free silver (Ag) nanofibers were prepared.

Referring to Figure 14 (b) it can be seen that after the oxidation time of 5 minutes, a thin Ag ₂ O shell of approximately 20 nm is formed. These observations indicate that the presence of Ag ₂ O shell with refractive index matching layer dominates the clarification.

15 illustrates a backscatter distribution of a metal network transparent electrode according to an embodiment of the present invention.

Referring to FIG. 15, backscattering distributions of Ag / Ag ₂ O nanofibers formed from silver (Ag) nanofibers with an initial diameter of 1700 nm are shown. A green laser with a wavelength of 532 nm was irradiated to the samples at an incidence angle of 60 degrees. It can be seen that the scattering distributions are quite localized after oxidizing for at least 5 minutes only for the Ag / Ag ₂ O nanofibers / refractive index matching layer (denoted “with IML”).

16 illustrates a forward scattering distribution of a metal network transparent electrode according to an embodiment of the present invention.

Referring to FIG. 16, (a) is a schematic diagram of a forward scattering measuring device, and (b) is a backscattering distribution. All oxidized samples had an Ag ₂ O shell thickness of 160 nm. It can be seen that forward scattering is suppressed in the case of clocked silver (Ag) nanofibers, that is, Ag / Ag ₂ O nanofibers / refractive index matching layer. In addition, in the case of the Ag / Ag ₂ O nanofibers / refractive index matching layer as described above, backscattering is also suppressed. This means that both external and internal surveys can be used universally.

In order to verify the above experimental results, finite-difference time-domain (FDTD) simulations were performed.

17 shows simulation results for optical characteristics under a lateral electric field of a metal network transparent electrode according to an embodiment of the present invention.

Referring to FIG. 17A, a schematic diagram of Ag / Ag ₂ O nanofibers on a glass substrate for simulation. Single hemispherical silver (Ag) nanofibers with conformal Ag ₂ O shells were placed on the glass substrate and inserted into the background medium of the air layer (refractive index is 1.0) or the dielectric layer (refractive index is 1.5). In order to clearly verify the effect of the Ag ₂ O shell, the diameter of the silver (Ag) core was not changed by the introduction of the Ag ₂ O shell. The diameter of the silver (Ag) nanofibers was set to 800 nm, and the thickness of the oxide layer (Ag ₂ O shell) was set to 160 nm. In the schematic diagram, the transverse electric field (TE) polarization and the transverse magnetic field (TM) polarization are defined.

Referring to FIG. 17B, electric field intensity profiles obtained from 530 nm wavelength transverse field polarized light are shown. Examining the electric field strengths of silver (Ag) nanofibers, Ag / AgO ₂ nanofibers, and Ag / AgO ₂ nanofibers / refractive index matching layers, as the oxide and refractive index matching layers are formed by the oxidation and coating steps, It can be seen that scattering is significantly suppressed.

Referring to FIG. 17C, it is a surface diagram showing wavelength-dependent scattering efficiency due to a change in lateral field polarized light. For further quantitative analysis, three structures of vertical incident broadband with transverse field polarization (wavelength in the range of 400 nm to 700 nm) with varying silver nanofiber diameters in the range of 260 nm to 1800 nm for plane waves It is the surface figure which measured the scattering cross section. These surface plots showed scatter suppression independent of magnitude preserved across the entire visible spectrum for transverse electric field polarization and correspond to measured scatter distributions as shown in FIG. 13. Bare silver (Ag) nanofibers retained intermittent high amplitude bands specified by local surface plasmon resonances. However, it can be seen that Ag / Ag ₂ O nanofibers covered with a dielectric layer significantly alleviate plasmon mediated scattering.

Referring to FIG. 17D, the electric field wavelength profile of an Ag / Ag ₂ O nanofiber / refractive index matching layer at an oxide layer thickness of 0 nm, 20 nm, or 100 nm obtained at a wavelength of 530 nm for lateral field polarization. Indicates. The diameter was 800 nm. To study clocked silver (Ag) nanofibers with a wide range of sizes, the effect of Ag ₂ O shell thickness is shown.

Referring to (e) of FIG. 17, it is a surface diagram showing wavelength-dependent scattering efficiency of Ag / Ag ₂ O nanofibers / refractive index matching layer according to a change in transverse field polarized light. The diameter was 800 nm. From the simulation results, it can be seen that when 20 nm of a very thin Ag ₂ O shell is introduced, scattering is rapidly suppressed. Thicker Ag ₂ O shells provide greater scatter suppression. The surface plot of scattering efficiency with varying Ag ₂ O shell thickness and wavelengths shows a blocking Ag ₂ O shell thickness which is approximately 20 nm in this simulation, and the scattering behavior changes rapidly. From these simulation results, it is possible to explain the measured scattering distributions with a slight increase in the Ag ₂ O shell thickness of FIG. 15.

FIG. 18 illustrates simulation results of optical characteristics under a lateral magnetic field of a metal network transparent electrode according to an exemplary embodiment of the present disclosure.

Referring to FIG. 18A, it is a surface diagram showing wavelength-dependent scattering efficiency due to a change in lateral magnetic field polarized light. Referring to FIG. 18B, the electric field wavelength profile of an Ag / Ag ₂ O nanofiber / refractive index matching layer at an oxide layer thickness of 0 nm, 20 nm, or 100 nm obtained at a wavelength of 530 nm for the transverse magnetic polarization Indicates. Referring to FIG. 18C, the surface-dependent scattering efficiency of the Ag / Ag ₂ O nanofibers / refractive index matching layer according to the change in the transverse magnetic polarized light is shown. The results for the lateral magnetic field polarized light of FIG. 18 agree well with the results for the lateral field polarized light of FIG. 17.

19 is a simulation result showing the effect of the oxide layer of the metal network transparent electrode according to an embodiment of the present invention.

Referring to FIG. 19, surface diagrams showing wavelength-dependent scattering efficiency of core / shell Ag / dielectric nanofibers (diameter is 800 nm) according to a change in dielectric thickness for transverse field polarized light. The refractive index (n) and the absorption coefficient (k) imposed on the dielectric shell are represented by (n, k) and described as (2.5, 0), (2.5, 0.1), (2.5, 0.5). The refractive index of the background medium was 1.5 and was set in the same manner as the refractive index matching layer used in the experiment. As a result, silver nanofibers with strong (k = 0.5), weak (k = 0.1), or transparent (k = 0) dielectric shells can be used to verify the effect of absorbent Ag ₂ O shells. Scattering efficiency was obtained. Comparing the surface diagrams, it can be seen that plasmon scattering induced by silver (Ag) nanofibers is suppressed when the dielectric shell is absorbable. Interestingly, the clocked silver (Ag) nanofibers with absorbent Ag ₂ O shell samples showed significantly higher transmissions than bare silver (Ag) nanofibers samples. In general, it is known that scattering and absorption are considerably related, so that the clocked structure can reduce the absorption and scattering cross sections.

In one application of the invention, a heater can be provided using clocked silver (Ag) nanofibers of random network structure, which can be used as a defrost device.

20 illustrates a method of manufacturing a heater constructed of a metal network transparent electrode according to an embodiment of the present invention.

Referring to (a) of FIG. 20, preparing nanofibers having a random network structure, forming conductive pads at both ends of the nanofibers, and forming a blocking layer on the conductive pads, the nanofibers. Surface oxidation, removing the barrier layer, and forming a refractive index matching layer on the nanofibers.

The nanofibers may be composed of a metal network transparent electrode, for example, the nanofibers may include silver (Ag) nanofibers. The conductive pad may include silver (Ag), and may be attached to silver (Ag) nanofibers using a silver (Ag) epoxy paste. The blocking layer is formed to prevent oxidation of the conductive pad, and may include, for example, PDMS. The silver (Ag) nanofibers could function as a transparent electrode for Joule heating and had a diameter of 750 nm. In addition, the sheet resistance (R _s ) was 4.8 ± 1.1 mA / sq, and the transmittance was 99%.

Referring to FIG. 20B, a schematic diagram of the completed heater is shown, and referring to FIG. 20C, a physical picture of the completed heater is shown.

21 illustrates exothermic experiment results of a heater constructed of a metal network transparent electrode according to an embodiment of the present invention.

Referring to (a) of FIG. 21, the input DC bias is increased to 6 V as a step of increasing 1 V every 30 seconds. The temperature change of the Ag / Ag ₂ O nanofibers / refractive index matching layer heater according to the increase of the DC bias is shown. As the magnitude of the DC bias increased, the temperature increased. As a result, the average temperature was found to be 248.2 ± 0.8 ° C.

Referring to Figure 21 (b), in order to verify the effect of the silver (Ag) nanofibers developed as a transparent electrode in the present invention, the Ag / Ag ₂ O nanofibers / refractive index matching layer (R A comparative example including _s = 1.9 Ω / sq) and silver (Ag) nanowires (R _s = 15 dl / sq) and a comparative example including indium tin oxide (R _s = 60 dl / sq) were further prepared. Thermal testing was performed by applying a DC bias of 2V. For comparison, the transmittance of these three samples was adjusted to the same value of 94% at 550 nm wavelength. In order to achieve this same transmittance, Ag / Ag ₂ O nanofibers of random network structure having an average diameter of 1139 nm were used, and the sheet resistance (R _s ) was 1.9 ± 0.5 W / sq. A sharp increase in the thermal equilibrium temperature was observed in the silver (Ag) nanofibers according to the embodiment of the present invention, which showed a tendency different from silver (Ag) nanowires having different sheet resistance and indium tin oxide.

Referring to (c) of FIG. 21, a thermal cycle test was performed by repeatedly applying a DC bias (6 V) at 50 cycles to an Ag / Ag ₂ O nanofibers / refractive index matching layer according to an embodiment of the present invention. No degradation of thermal performance was found throughout the entire test.

Referring to (d) of FIG. 21, infrared photographs of the thermal radiation test of (c) are shown. The Ag / Ag ₂ O nanofibers / refractive index matching layer, which is an embodiment of the present invention, exhibited a uniform temperature distribution at a uniform direct current bias. This means that it has excellent properties applied to the heater.

Referring to Figures 21 (e) and (f), here, in order to reach the same thermal equilibrium temperature of 120 ° C, the Ag / Ag ₂ O nanofibers / refractive index matching layer of Direct current bias was applied, silver (Ag) nanowires were applied with a direct current bias of 5.5 V, and an 11 V direct current bias was applied to the indium tin oxide layer. The Ag / Ag ₂ O nanofibers / refractive index matching layer of the present invention showed a higher heating rate and cooling rate than other comparative examples of silver (Ag) nanowires and indium tin oxide. This result is because Ag / Ag ₂ O nanofibers / index matched layers have a relatively faster heat transfer rate.

22 illustrates heat transfer test results of the metal network transparent electrode according to the exemplary embodiment of the present invention.

Referring to FIG. 22A, an electrode composed of Ag / Ag ₂ O nanofibers / refractive index matching layer of an embodiment of the present invention, an electrode composed of silver (Ag) nanowires as a comparative example, and indium as a comparative example An electrode composed of tin oxide was prepared. The electrodes were each prepared on a 25 μm thick polyimide substrate. One end of the electrodes was connected to a hot plate having a uniform temperature of 140 ° C., and the other end of the electrodes was connected to a cooling pad having a uniform temperature of 23 ° C.

In FIG. 22B, infrared photographs of the electrodes are shown. 22C shows the temperature change of the electrodes according to the distance from the heating plate. From the above results, the electrode composed of Ag / Ag ₂ O nanofibers / refractive index matching layer of the present invention showed relatively faster thermal radiation. The large thermal and optical capabilities of these clocked silver (Ag) nanofibers can be suitably applied to defrosting devices requiring high transparency, high transmittance, and high defrost rates.

FIG. 23 illustrates defrost test results of a heater configured of a metal network transparent electrode according to an exemplary embodiment of the present invention.

Referring to FIG. 23A, a graph showing defrost time of Ag / Ag ₂ O nanofibers / refractive index matching layer heater according to changes of applied DC biases. Defrosting devices fabricated using clocked silver (Ag) nanofibers (surface resistance (R _s ) is 4.8 ± 1.1 μs / sq and transmittance is 99%) are linear between the defrost time and the applied direct current bias. The relationship is shown. The defrost time was less than 1 second at a 6 V direct current bias. This rapid defrost is analyzed to be desirable for automotive glass that requires a clear view while driving.

Referring to (b) and (c) of FIG. 23, pictures of Ag / Ag ₂ O-nanofiber / refractive index matching layer heater applied to automobile glass, (b) are before operation, and (c) is right after operation. to be. The applied direct current bias was 6 V. The pictures inside the lower side represent the driver's field of view, and the pictures inside the upper side are the ultraviolet image showing the temperature distribution of the glass. Defrosted tests were performed by applying clocked silver (Ag) nanofibers to automotive glass. Frost intentionally formed throughout the vehicle glass evaporated completely within 1 second at a 6 V direct current bias.

As described above, broadband transparent clocking is not limited to silver (Ag) wiring but may be applied to mesoscopic particles and flakes of metal such as copper, which can be used as a low cost electrode material. The effect of scatter suppression can be increased by the design of the shell and cover layers. For example, it is a double shell combined with a high-index cover layer. These experimental and theoretical results can be used for the development of various applications that require high transparency fields of view and use metal structures.

Metal network transparent electrode according to the spirit of the present invention, the metal nanomaterial core having a network structure; An oxide layer disposed on the metal nanomaterial core; And a refractive index matching layer disposed on the oxide layer.

The metal nanomaterial core may be composed of various metals, for example, silver (Ag), gold (Au), platinum (Pt), copper (Cu), chromium (Cr), gallium (Ga), nickel (Ni) ), Or alloys thereof.

The oxide layer may be composed of various oxides, for example, the oxide of the metal nanomaterial core. Alternatively, the oxide layer may be formed through an additional deposition method, and in this case, the oxide layer may be formed of an oxide of a material different from that of the metal nanomaterial. The oxide layer may include, for example, Ag ₂ O, Fe ₂ O ₃ , CuO, indium tin oxide (ITO), indium gallium zinc oxide (IGZO), or ZnO.

The refractive index matching layer may include various materials, and may include, for example, silicon oxide or a transparent polymer.

The refractive index matching layer may have, for example, a refractive index in the range of 1 to 6.

The metal nanomaterial core and the oxide layer may have the same or similar refractive index.

The network structure may be a random network structure.

The metal nanomaterial core may have various diameters, for example may have a diameter in the range of 100 nm to 20000 nm, and for example may have a diameter in the range of 300 nm to 1800 nm.

The oxide layer may have various thicknesses, for example, may have a thickness in the range of 5 nm to 1000 nm, and for example, may have a thickness in the range of 100 nm to 200 nm.

It may further include a cavity region disposed between the metal nanomaterial core and the oxide layer.

Metal network transparent electrode according to the spirit of the present invention, a metal core formed of a metal material having a network structure; An oxide layer disposed on the metal core; And a refractive index matching layer disposed on the oxide layer.

Method of manufacturing a metal network transparent electrode according to the technical idea of the present invention, forming a metal network by electrospinning a metal nanomaterial; Oxidizing a surface of the metal network to form an oxide layer; And forming a refractive index matching layer on the oxide layer; It includes.

The forming of the oxide layer may be performed in various ways, for example, by performing ultraviolet ozone irradiation on the metal network.

The forming of the refractive index matching layer may be performed in various ways, for example, using a Meyer rod coating method.

Method of manufacturing a metal network transparent electrode according to the technical idea of the present invention, forming a network by electrospinning a polymer; Depositing a metal nanomaterial on the network to form a metal network; Transferring the metal network to a substrate; Removing the polymer; Oxidizing a surface of the metal network to form an oxide layer; And forming a refractive index matching layer on the oxide layer.

The polymer may include various polymers, for example polyvinylpyrrolidone.

Removing the polymer may be performed in a variety of ways, for example using ethanol.

Heater according to the technical idea of the present invention, a metal nanomaterial core having a network structure; An oxide layer disposed on the metal nanomaterial core; And a refractive index matching layer disposed on the oxide layer.

Method for manufacturing a heater according to the technical idea of the present invention, a metal nanomaterial core having a network structure; An oxide layer disposed on the metal nanomaterial core; Preparing a nanofiber consisting of a metal network transparent electrode comprising a; refractive index matching layer disposed on the oxide layer; Forming conductive pads at both ends of the nanofibers; Forming a blocking layer on the conductive pad; Surface oxidation of the nanofibers; Removing the barrier layer; And forming a refractive index matching layer on the nanofibers.

The technical spirit of the present invention described above is not limited to the above-described embodiment and the accompanying drawings, and various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in the art.

Claims (20)

A metal nanomaterial core in which metal nanowires form a network structure;
An oxide layer formed to surround the surfaces of the metal nanowires and formed by oxidizing a metal material forming the metal nanowires; And
A refractive index matching layer formed on the oxide layer,
And a cavity region is formed between the metal nanowire and the oxide layer. The method according to claim 1,
The metal nanomaterial core includes silver (Ag), gold (Au), platinum (Pt), copper (Cu), chromium (Cr), gallium (Ga), nickel (Ni), or alloys thereof Network transparent electrode. delete The method according to claim 1,
And the oxide layer is formed through a deposition method. The method according to claim 1,
The oxide layer comprises Ag ₂ O, Fe ₂ O ₃ , CuO, ITO, IGZO, or ZnO. The method according to claim 1,
And the refractive index matching layer comprises silicon oxide or a transparent polymer. The method according to claim 1,
And the refractive index matching layer has a refractive index in the range of 1-6. The method according to claim 1,
And the metal nanomaterial core and the oxide layer have the same refractive index. The method according to claim 1,
And the network structure consists of a random network structure. The method according to claim 1,
The metal nanomaterial core has a diameter in the range of 100 nm to 20000 nm. The method according to claim 1,
And the oxide layer has a thickness in the range of 5 nm to 1000 nm. delete delete Electrospinning the metal nanomaterial to form a metal network in which the metal nanowires form a network structure;
Oxidizing the surface of the metal nanowires to form an oxide layer and simultaneously forming a cavity region in which the surface of the oxide layer and the metal nanowires are separated from each other; And
Forming a refractive index matching layer on the oxide layer;
Comprising, a metal network transparent electrode manufacturing method. The method according to claim 14,
The forming of the oxide layer is performed by irradiating the metal network with ultraviolet ozone. The method according to claim 14,
The forming of the refractive index matching layer is performed using a Meyer rod coating method. Electrospinning the polymer in the form of nanowires so that the polymer nanowires form a network;
Depositing a metal nanomaterial on the polymer nanowires to form a metal network;
Transferring the metal network to a substrate;
Removing the polymer nanowires from the metal network to form a network structure of hollow metal nanowires;
Oxidizing the surface of the hollow metal nanowires to form an oxide layer, and simultaneously forming a cavity region in which the oxide layer and the surfaces of the hollow metal nanowires are separated from each other; And
Forming a refractive index matching layer on the oxide layer;
Comprising, a metal network transparent electrode manufacturing method. The method according to claim 17,
The polymer comprises polyvinylpyrrolidone,
Removing the polymer is performed using ethanol. delete delete

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