KR102006533B1 - Manufacturing method of nanorods by plasma - Google Patents

Abstract

The present invention relates to a method of making nanorods of ionic bond materials using metal and plasma on any substrate. The nanorod growth method of the present invention can grow nanorods in a short time within a few minutes at low temperature.
In addition, since only metal deposition and plasma reaction are used, it can be used in a roll-to-roll process.
According to one embodiment of the present invention, when any plastic is used as a substrate, stress is generated by metal and plasma reactions to warp the plastic substrate, thereby enabling faster nanorod growth.

Description

Manufacturing Method of Nano Rod Using Plasma {MANUFACTURING METHOD OF NANORODS BY PLASMA}

The present invention relates to a method for forming nanorods on various substrates, such as plastic substrates and glass, and more particularly, to a method for forming nanorods on a substrate in a short time at a low temperature using a metal and plasma reaction.

In recent years, the importance of flexible characteristics of electronic devices has been increasing. Accordingly, electronic devices such as organic light emitting diodes, liquid crystal displays, electrophoretic devices, plasma display panels, thin film transistors, microprocessors, RAMs, solar cells, and the like, It is formed on a plastic film with flexible characteristics.

An organic light emitting device, which is a typical organic electronic device, typically includes a substrate, a first electrode layer, an organic layer, and a second electrode layer sequentially. In this case, the substrate and the first electrode layer may be transparent, and the second electrode layer may be formed as a reflective electrode layer in a structure called a bottom emission OLED. In this case, most of the photons generated in the organic layer pass through the substrate and are released into the air.

One of the techniques for greatly improving the light output in such an organic light emitting diode is to pattern the substrate on which light is emitted. In the case of a smooth flat surface, high light output cannot be expected because a large part of the light generated in the active layer cannot escape to the outside due to total reflection occurring at the atmosphere / substrate interface. Therefore, it is necessary to maximize the light extraction efficiency by artificially forming a nanostructure on the surface of the substrate to prevent total reflection from occurring and to let the light escape to the outside with minimal loss.

The nanorod growth methods reported to date include vapor-liquid-solid (VLS) method, thermal oxidation method, and hydrothermal synthesis method.

In the case of the VLS method, nanorods are grown using a metal particle catalyst such as Au. Precursor gas is dissolved in the metal catalyst and precipitates under the catalyst when the amount of melting is greater than solubility to form a solid nanorod.

In addition, in the thermal oxidation method, stress and strain are applied to the oxide material formed by heating a metal in an oxygen atmosphere due to a lattice constant difference with a metal substrate below, and nanorods are grown to alleviate the stress.

In addition, in the case of hydrothermal synthesis, when a substrate is placed in a solution in which a precursor is dissolved, nanorods are grown by electrostatic attraction of precursor ions.

Since the VLS method and the thermal oxidation method require a high temperature (> 400 ° C.), it is difficult to apply to a plastic substrate, which is a flexible material, and causes a lot of damage to other materials.

In addition, the hydrothermal synthesis method can grow nanorods at low temperature (about 100 ° C.), but has a disadvantage that the growth rate is slow to about 1 nm per minute.

In addition, various methods of forming nanorods have been reported, but there is a lack of technology for forming nanorods at a high speed in large areas at low temperatures. Therefore, there is a need to develop a technology for forming nano bars (structures) that can be applied to various fields and can be applied to a roll-to-roll process for large-area production.

Republic of Korea Patent Publication No. 10-2012-0096850

Disclosure of Invention Problems to be solved by the present invention are applicable to various fields, and provide a method for growing nanorods at a high speed at large speed at low temperature.

The present invention includes the steps of preparing a substrate having a metal layer formed on the surface, and performing a plasma treatment on the metal layer, wherein, during the plasma treatment, the reaction of the metal of the metal layer and gas radicals in the plasma A method of manufacturing nanorods in which nanorods made of ionic bond materials are produced in the process of forming ionic bond materials on the surface and mitigating strain energy caused by lattice mismatch between the ionic bond material and the metal constituting the metal layer. To provide.

The nanorods may be one of metal oxides, metal chlorides, or metal nitrides.

In addition, the nanorods may have a single crystal or polycrystalline structure.

In addition, it is possible to control the size of the nanorods formed through the thickness of the deposited metal and the plasma treatment conditions, thereby providing a method of controlling the optical properties of any substrate.

In addition, when the plastic film is used as the substrate, strain generated by the lattice mismatch during the plasma treatment causes the substrate to bend, and thus the curved substrate promotes the diffusion of the metal to enable faster nanorod growth.

In addition, the metal may include one or an alloy thereof selected from Li, Na, Mg, K, Ti, Fe, Ni, Co, Cu, Zn, Ag, Au, Sn, and In.

In addition, the metal may be a metal film of a type deposited on a foil or an arbitrary substrate by using physical vapor deposition (PVD).

In addition, in the case of using a metal film deposited by physical vapor deposition, the thickness of the deposited metal film is preferably 5 nm or more, because when the thickness of the metal film is less than 5 nm, less ionic compounds are formed and nanorods are not formed. It is possible to control the length, diameter, period, etc. of the nanorod formed by adjusting the thickness of the metal film. Permeability and haze can be controlled by adjusting the length, diameter, and period of the nanorods.

In addition, the gas used in the plasma treatment may include at least one selected from the group consisting of O ₂ , N ₂ , He, Ar, SiH ₄ , NF ₃ , CF ₄ , N ₂ O, Cl ₂ , BCl ₄ , NH ₃ . Can be.

It is also possible to control the size and shape of the nanorods generated by plasma processing conditions, such as plasma processing time, power, or pressure.

In addition, the substrate is polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), polyurea (PUA), polyimide (Polyimide), SU-8 (epoxy series photocurable resin It may be a plastic substrate containing one or more materials selected from the group consisting of a combination of CHO, or a metal substrate made of glass, sapphire, silicon, or metal.

In addition, when the plastic substrate is used, the substrate is bent due to stress and strain formed during the plasma reaction, and the nanorod growth can be accelerated by using the bending property of the substrate.

The nanorod manufacturing method of the present invention can grow the nanorods at a short time within a few minutes at low temperature.

In addition, since only metal deposition and plasma reaction are used, it can be easily applied to a roll-to-roll process.

The transparent substrate on which the ion-bonding material of the present invention is formed shows excellent light scattering degree. For example, the average haze may be 100% in the visible region in the wavelength range of 400 nm to 800 nm. Since the transparent substrate according to the present invention has excellent light scattering degree, the transparent substrate may be suitably used as a substrate of the organic light emitting device of the bottom emission type.

1 is a schematic diagram of a method for preparing AgCl nanorods through chlorine plasma treatment after Ag is deposited on an arbitrary substrate according to a preferred embodiment of the present invention.
FIG. 2 shows a scanning electron micrograph in which a 300 nm-thick Ag thin film is deposited on a polyimide, polyethylene terephthalate, and soda-lime glass substrate according to a preferred embodiment of the present invention, and then observed changes with chlorine plasma treatment time. .
Figure 3 shows that it is possible to control the size of the AgCl nanostructure formed through the thickness control of the deposited Ag thin film according to a preferred embodiment of the present invention, thereby controlling the transmittance haze of the optical properties.
Figure 4 shows the state of the Ag thin film deposited according to a preferred embodiment of the present invention and the XPS and electrical properties after chlorine plasma treatment.
Figure 5 shows a transmission electron micrograph and XRD results of the AgCl nanorods formed in accordance with a preferred embodiment of the present invention.
Figure 6 shows the difference in growth rate of the nanorods when using a plastic, glass and sapphire material as a substrate.
7 is a diagram illustrating the application of a nanorod manufacturing process to a roll-to-roll process according to a preferred embodiment of the present invention.
8 is a diagram illustrating the efficiency of an organic electronic device manufactured by using a plastic substrate on which a nanorod formed according to a preferred embodiment of the present invention is formed.
9 is a diagram showing the bending test results of the nanorods manufactured according to the preferred embodiment of the present invention.

Hereinafter, the present invention will be described in more detail based on the preferred embodiments of the present invention. However, the following examples are merely examples to help the understanding of the present invention, and thus the scope of the present invention is not reduced or limited.

[Example]

AgCl  Manufacture of nano-rods

As shown in FIG. 1, a polyethylene terephthalate (PET) substrate, a polyimide (PI) substrate, and a soda-lime glass substrate were prepared.

Ag was deposited to a thickness of 300 nm on the surfaces of the substrates using an electron beam evaporator.

Subsequently, chlorine plasma treatment was performed under the conditions of 350 W of power, 10 mTorr of gas pressure, and 10 sccm of gas supply flow rate. As a result, AgCl nanorods were formed as ion-bonds.

As shown in FIG. 2, when the above-described plasma treatment is performed, the speed at which the nanorods are formed varies depending on the thickness of the substrate, and when the polyimide substrate is 100 μm thick, after 30 seconds, the glass substrate is 700 μm thick. In the case of using, it was confirmed that the nanorods grow after 90 seconds.

As shown in Figure 3, the size and optical properties of the resulting nanorods can be adjusted by changing the thickness of the Ag thin film. For example, when the Ag thin film thickness is 10 nm, AgCl has a parabolic nanostructure of sub-wavelength size.

As the Ag thin film thickness increases, AgCl grows in the form of nanorods and is oriented perpendicular to the substrate. The average period and average diameter of the AgCl nanostructures were measured with the Ag film thickness, and the average period increased linearly from 60nm to 690nm. In the case of the average diameter, it can be seen that the Ag thin film thickness is increased up to 200 nm.

In addition, in order to analyze how the optical properties change as the size of the AgCl nanostructure changes, the total transmittance and haze were measured in the visible region (400 nm to 800 nm) using an integrating sphere. Haze refers to the degree of scattering of light.

For the untreated PI film, the average transmittance was 89.4% and haze 0.22% in the visible region.

In the case of the sub-wavelength AgCl nanostructure (that is, Ag thin film thickness = 10 nm), the average transmittance was 93.2% and the haze was 0.27%. As the Ag thin film thickness increases, the average transmittance decreases and the haze increases. When the Ag film thickness is greater than 300 nm, all light is scattered with a haze of 100%. AgCl nanorods with 100% haze scatter light and can be used to extract light trapped in an organic light emitting diode substrate for illumination.

That is, according to a preferred embodiment of the present invention, the AgCl nanostructure size can be adjusted only by controlling the thickness of the Ag thin film formed on the substrate, through which the scattering of light can be adjusted from 0% to 100%.

The crystal structure of the AgCl nanorods formed as shown in FIG. 5 was analyzed by transmission electron microscope (TEM). SAED (Selected Area Electron Diffraction) pattern shows a single crystal peak and shows some defects. This is due to the property that AgCl decomposes to Ag under high energy electron beam. The high-resolution TEM images showed that the interplanar distances measured at 2.77Å and 3.20Å coincident with the (111) and (200) interplanar distances of AgCl, indicating that the AgCl nanorods were grown into single crystals. Confirmed growth.

The reason why the growth of the nanorods is faster than the substrates of other materials may be interpreted as the spontaneous bending of the substrate (ie, the film) during the plasma treatment. Due to the lattice mismatch between the Ag thin film formed on the plastic substrate and the generated AgCl during the plasma treatment, the strain energy is generated and the flexible and thin plastic film is bent to minimize it. However, it was confirmed that the thick glass did not bend.

Finite element method (FEM) simulations were performed to analyze how the substrate flexure affects nanorod growth.

The reaction of Ag and Cl radicals was approximated to expand the volume of the Ag thin film. Strain gradient distributions in PI films and glass substrates were calculated when volume expansion occurred. Volume expansion causes the PI film to bend convexly and relieve deformation. This creates a strain gradient at the Ag / AgCl interface and concentrates the strain gradient toward the edge of the nanorods.

In contrast, in the case of a substrate made of hard glass, a high degree of stiffness causes constant deformation and almost no deformation gradient. Strain gradient value at the nano-rod end (edge) is a value of ^-1 0.79㎛ 11.0㎛ ^-1, the glass in the PI film. This strain gradient leads to strain-induced diffusion, which can be understood by Equation 1 below.

[Formula 1]

(Where J is atomic flux, C is atomic concentration, Ω is atomic volume, D is diffusion coefficient, E is Young's modulus, k _B is Boltzmann's constant, T is absolute temperature and ε is strain) do)

In general, since diffusion due to the strain gradient is dominant at low temperature, diffusion due to the strain gradient is considered to be determined by diffusion due to the strain gradient.

Based on the above calculation results, it was confirmed that more strain gradients were concentrated in the PI film, thereby facilitating strain-organic diffusion of Ag atoms, thereby enabling faster growth.

Figure 7 is a diagram showing the application of the manufacturing process of the nanorods in a roll-to-roll process according to a preferred embodiment of the present invention.

As shown in FIG. 7, a metal thin film is formed by using a metal thin film deposition apparatus disposed below in the process of supplying a flexible plastic substrate (eg, PI substrate) supplied in a roll form on the left side using a roll. Then, plasma treatment is performed on the portion where the metal thin film is formed by using a plasma apparatus (not shown), so that the large-area plastic substrate can be rapidly processed (a time within several seconds for the plastic film in the above-described embodiment). The rod can be formed. That is, the method according to the embodiment of the present invention can be used suitably for the roll-to-roll method.

Manufacture of organic electronic devices

As shown in the upper left of Figure 8, using a PI substrate formed with the AgCl nanorods prepared by the method described above, a hole injection electrode layer, a hole injection layer, a hole transport layer, a light emitting layer electron transport layer, an electron injection layer and an electron column The granular electrode layer was formed using a thermal evaporator to manufacture an organic electronic device.

WO ₃ 36nm, Ag 12nm, WO ₃ 3nm, hole injection layer CBP: WO ₃ 230nm, hole transport layer CBP 10nm, light emitting layer CBP: Ir ( ppy) 3 30nm, TPBi 45nm as the electron transport layer, 1F electron injection layer LiF 1nm, the electron injection electrode layer formed Al 100nm to manufacture an organic electronic device.

In order to verify the flexibility of the AgCl nanorods (Ag thin film thickness = 200nm) manufactured by the above method as shown in FIG. 9, tests were performed according to various radii of curvature and bending times.

As a result of the test, it was confirmed that the AgCl nanorods did not change until the radius of curvature was 1.73 mm. In addition, when the number of bending was increased to 10,000 times at a radius of curvature of 1.73 mm, it was confirmed that the nanorod form was not collapsed or cracked. As the average transmittance and haze of optical properties do not change with the number of bending, it can be seen that the AgCl nanorods have excellent flexibility.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. In addition, it is a matter of course that various modifications and variations are possible without departing from the scope of the technical idea of the present invention by anyone having ordinary skill in the art.

Claims (11)

Preparing a substrate having a metal layer formed on a surface thereof to form an ion-bonding material through reaction with gas radicals in the plasma, and performing a plasma treatment including a gas radical capable of forming an ion-bonding material with the metal layer. Including;
In the plasma treatment, an ion-bonding material is formed on the surface of the metal layer through a reaction between the metal of the metal layer and gas radicals in the plasma, and is generated due to lattice mismatch between the ion-bonding material and the metal constituting the metal layer. Method of manufacturing a nanorod using a plasma, characterized in that to produce a nanorod made of an ion-bonding material in the process of mitigating strain energy. The method of claim 1,
The ion-bonding material is one of a metal oxide, a metal chloride, or a metal nitride, characterized in that the manufacturing method of the nanorod using plasma. The method of claim 1,
The metal layer is a metal containing at least one element selected from Li, Na, Mg, K, Ti, Fe, Ni, Co, Cu, Zn, Ag, Au, Sn, In, using a plasma Method of manufacturing nanorods. The method of claim 1,
The gas used for the plasma treatment includes one or more selected from the group consisting of O ₂ , N ₂ , He, Ar, SiH ₄ , NF ₃ , CF ₄ , N ₂ O, Cl ₂ , BCl ₄ , NH ₃ . The method of manufacturing a nanorod using a plasma, characterized in that. The method of claim 1,
The substrate is polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), polyurea (PUA), polyimide, SU-8 (epoxy series photocurable resin) Method for producing a nanorod using a plasma, characterized in that consisting of a plastic, glass, sapphire, silicon, or a metal containing at least one material selected from the group consisting of a combination of CHO. The method of claim 1,
The nanorod has a single crystal or polycrystalline structure, characterized in that the manufacturing method of the nanorod using plasma. The method of claim 1,
The metal layer is a metal film formed through a metal foil (foil) or physical vapor deposition (PVD), characterized in that the manufacturing method of the nano-rod using plasma. The method of claim 1,
The method of manufacturing a nanorod using a plasma, characterized in that for controlling the size and shape of the nanorods generated, through time, power, or pressure during the plasma treatment. The method of claim 5,
When the substrate is made of plastic, the substrate is bent by the stress generated during the plasma processing, characterized in that to promote the nanorod growth by using the bending characteristics of the substrate, a method of manufacturing a nanorod using a plasma. The method of claim 7, wherein
The thickness of the metal film is 1nm ~ 3000nm, characterized in that for adjusting the length, diameter or period of the pattern of the nanorods generated by adjusting the thickness of the metal film, a method for manufacturing nanorods using plasma. The method of claim 10,
The nanorods manufacturing method using a plasma, characterized in that for controlling the permeability and haze of the substrate by adjusting the length, diameter, or pattern of the nanorods.

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