A color or black electrode and its preparation method

Abstract

The present invention relates to a color or black electrode with high color rendering property and low resistance characteristics and a preparation method thereof. The color electrode is composed of a metal reflection layer, a dielectric modulation layer, a metal absorption layer and an antireflection layer, and the black electrode is composed of a metal reflection layer, a dielectric modulation layer-metal absorption layer stack and an antireflection layer; each of the above layers has a low resistivity. The electrode of the present invention can achieve high-saturation color display or low-reflection full black display in the visible light band and has a very low resistance. Therefore, the color or black electrode of the present invention can be widely applied to fields such as photovoltaics and displays.

Description

Technical Field

[0001] The present invention belongs to the fields of display, imaging, detection, decoration, etc., and particularly relates to a colored or black electrode and a preparation method thereof. Background Art

[0002] Existing electrode materials can be divided into various categories, mainly including metal electrodes, transparent conductive electrodes, nanostructured metal electrodes (such as conductive silver paste), and graphene, etc. These electrodes are widely used in the fields of electronics, optoelectronics, energy, etc., and have different characteristics and advantages.

[0003] Metal electrodes: Metal electrodes have high electrical conductivity and excellent electrical contact performance. Common metal electrode materials include copper, aluminum, nickel, gold, silver, etc. Metal electrodes are widely used in the fields of electronic devices, sensors, batteries, etc.

[0004] Transparent electrodes: Transparent conductive electrodes have good electrical conductivity and light transmittance. Common transparent conductive electrode materials include indium tin oxide (such as ITO) and tin fluoride (such as FTO), etc. Transparent conductive electrodes are mainly used in the fields of displays, touchscreens, solar cells, etc.

[0005] Nanostructured metal electrodes: Nanostructured metal electrodes are conductive thin films composed of nano metal particles (such as silver paste). Such electrodes have high electrical conductivity and plasticity, and are suitable for flexible electronic devices, wearable devices, etc.

[0006] Graphene, etc.: Graphene is a two-dimensional material with excellent electrical conductivity, high strength, and good flexibility. Graphene electrodes can be used in various high-performance electronic devices, energy storage, and sensors, etc.

[0007] However, in some special occasions, such as concealed devices, decorative electronic products, automotive applications, etc., there are special requirements for the color of the electrodes, such as the need for colored or black electrodes. In addition, black electrodes can reduce light reflection and improve the display effect and contrast of the device.

[0008] Although existing electrode materials have certain advantages in terms of electrical conductivity, light transmittance, and flexibility, they cannot meet the requirements for colored or black electrodes in special occasions. For example, metal electrodes and nanostructured metal electrodes are usually silver or gold in color, transparent conductive electrodes have a certain light transmittance, and although graphene appears grayish black, it is limited in terms of thickness. Therefore, it is difficult for existing electrode materials to meet the requirements for colored or black electrodes.

[0009] To solve this problem, it is very necessary to research and develop new colored or black electrode materials. These new materials should have characteristics such as good electrical conductivity, color controllable, customizable, and compatible with existing technologies. Summary of the Invention

[0010] The object of the present invention is to provide a color or black electrode and a preparation method thereof, which electrode has directional absorption in a certain wavelength band and has a low resistance.

[0011] The object of the present invention is to provide a color or black electrode and a preparation method thereof, which electrode has directional absorption in a certain wavelength band and has a low resistance.

[0012] To achieve this object, the present invention provides the following technical solutions:

[0013] The present invention constructs an evaluation function to characterize the indexes of the color or black electrode:

[0014]

[0015] Where N is the number of wavelength points, j is the number of film layers, d is the film layer thickness, α, β and γ are the weights of the spectrum, resistance and regularization term for the evaluation function, and R target is the spectral target we need to design, and different colors correspond to different Rs target , n is the complex refractive index of the thin film, which is related to the thin film material and the incident wavelength, R represents the spectral data actually calculated and is related to the thickness d and refractive index n, and ρ all represents the resistance of the entire electrode, which is related to the film layer thickness and the resistance ρ of each layer. ρ1, ρ2, etc. represent the resistances of different film layers. The smaller the evaluation function, the more accurate the color of the electrode and the lower the resistance. We use this evaluation function to co-design our entire electrode.

[0016] A color or black electrode, which electrode comprises a substrate, and sequentially provided with a metal reflection layer, one or more groups of dielectric modulation layer-metal absorption layer stacks and an antireflection layer on the substrate, and the sheet resistance of each layer is less than or equal to 20 Ω / sq; when the stack is multiple groups, the bottom layer is a dielectric modulation layer and the top layer is a metal absorption layer.

[0017] Furthermore:

[0018] A color electrode, which electrode comprises a substrate, and sequentially provided with a metal reflection layer, a dielectric modulation layer, a metal absorption layer and an antireflection layer on the substrate, and each layer has a low resistance; the incident light is incident from the side of the antireflection layer.

[0019] A black electrode, characterized in that the electrode comprises a substrate, and sequentially provided with a metal reflection layer, a dielectric modulation layer-metal absorption layer stack and an antireflection layer on the substrate, and each layer has a low resistance; the dielectric modulation layer-metal absorption layer stack is composed of a dielectric modulation layer and a metal absorption layer alternately arranged; the bottom layer of the dielectric modulation layer-metal absorption layer stack is a dielectric modulation layer and the top layer is a metal absorption layer; the incident light is incident from the side of the antireflection layer.

[0020] The following is a preferred solution based on the above solution:

[0021] There is no limitation on the substrate material. Preferably, the substrate can be selected from glass materials such as K9, fused quartz, float glass, etc., semiconductor materials such as silicon, gallium arsenide, etc., plastic materials such as PET, PC, PI, etc., or alloy materials such as stainless steel. Further preferably, it is a silicon wafer.

[0022] Preferably, the metal reflective layer can be selected from silver, aluminum, gold, platinum, chromium, titanium, iridium, tungsten, nickel, cadmium, and alloys of the above materials; further preferably, the reflective layer can be selected from aluminum. The thickness of the metal reflective layer should be greater than or equal to 100 nm; further preferably, it is 100 - 500 nm; more preferably, it is 100 - 300 nm.

[0023] Preferably, the metal absorption layer can be selected from chromium, titanium, iridium, tungsten, nickel, cadmium, and alloys of the above materials; further preferably, the metal absorption layer can be selected from chromium. The thickness of the metal absorption layer should be less than 100 nm; further preferably, it should be less than 50 nm; more preferably, it is 4 - 30 nm.

[0024] Preferably, the dielectric modulation layer should have a certain conductivity and can be selected from oxides of indium, tin, antimony, zinc, and chromium, mixtures of the above materials, or doped mixtures thereof; further preferably, the dielectric modulation layer can be selected from indium tin oxide. The thickness of the dielectric modulation layer should be greater than 30 nm; further preferably, it is 40 - 500 nm.

[0025] Preferably, the antireflection layer should have a certain conductivity. The single - layer antireflection layer material can be selected from oxides of indium, tin, antimony, zinc, and chromium, mixtures of the above materials, or doped mixtures thereof; further preferably, the antireflection layer can be selected from indium tin oxide (ITO). The thickness of the antireflection layer should be greater than 20 nm; further preferably, it is 50 - 300 nm. In addition, in order to further reduce the surface reflectivity, an antireflection layer can be composed of a low - refractive - index organic conductive film and an inorganic conductive film. The organic conductive film material can be selected from polyaniline, polypyrrole, PEDOT:PSS, or its derivatives, etc.; further preferably, the organic conductive film can be selected from PEDOT:PSS. The thickness of the organic conductive film should be greater than 20 nm; further preferably, it is 50 - 300 nm.

[0026] Preferably, the dielectric modulation layer - metal absorption layer stack is formed by stacking multiple groups of dielectric modulation layer - metal absorption layers. Further preferably, the dielectric modulation layer - metal absorption layer stack is formed by stacking 2 - 5 groups of dielectric modulation layer - metal absorption layers.

[0027] As a specific preference, a blue electrode is composed of a substrate, a metal reflection layer (select silver) sequentially disposed on the substrate, a dielectric regulation layer (indium tin oxide), a metal absorption layer (chromium), and an anti-reflection layer (thin indium tin oxide). The thicknesses are 100 - 120 nm, 90 - 120 nm, 5 - 20 nm, and 50 - 100 nm respectively.

[0028] As a specific preference, a green electrode is composed of a substrate, a metal reflection layer (select silver) sequentially disposed on the substrate, a dielectric regulation layer (indium tin oxide), a metal absorption layer (chromium), and an anti-reflection layer (thin indium tin oxide). The thicknesses are 100 - 120 nm, 90 - 120 nm, 5 - 20 nm, and 120 - 200 nm respectively.

[0029] As a specific preference, a red electrode is composed of a substrate, a metal reflection layer (select silver) sequentially disposed on the substrate, a dielectric regulation layer (indium tin oxide), a metal absorption layer (chromium), and an anti-reflection layer (thin indium tin oxide). The thicknesses are 100 - 120 nm, 140 - 200 nm, 5 - 20 nm, and 40 - 100 nm respectively.

[0030] As a specific preference, a black electrode is composed of a substrate, a metal reflection layer (select silver, aluminum) sequentially disposed on the substrate, a dielectric regulation layer I (indium tin oxide), a metal absorption layer I (chromium), a dielectric regulation layer II (indium tin oxide), a metal absorption layer II (chromium), and an anti-reflection layer (thin indium tin oxide). The thicknesses are 100 - 120 nm, 140 - 300 nm, 15 - 45 nm, 50 - 100 nm, 10 - 20 nm, and 40 - 100 nm respectively.

[0031] The present invention also provides a method for preparing a colored or black electrode, including the following steps:

[0032] (1) According to the required electrode color, by optimizing the thickness of each thin film layer, a film system meeting the requirements is designed; this step can be implemented using existing software;

[0033] (2) The substrate is ultrasonically treated in an acetone solution, and then the substrate is cleaned with ethanol; then the substrate is ultrasonically treated in an ethanol solution, and then the substrate is cleaned with deionized water; finally, the substrate is ultrasonically treated in deionized water, and then the substrate is cleaned with deionized water again;

[0034] (3) Each film layer is sequentially deposited by vacuum coating to obtain the required black or colored electrode;

[0035] As a preference, in step (2), the ultrasonic treatment time each time is generally 5 - 30 min; more preferably 5 - 10 min.

[0036] During the optimization phase or after optimization is completed, the above evaluation function can be used to evaluate the film system parameters obtained each time or finally to ensure the accuracy of the finally obtained film system parameters.

[0037] A black electrode of the present invention is based on an alternating metal-dielectric multilayer film structure with upper transparency and lower opacity. Utilizing the spiral characteristics of the admittance repeating gyration, the low reflection characteristic, i.e., the high absorption characteristic, in the visible light band of the black electrode is realized. This multilayer film structure can generate perfect absorption resonances with overlapping multi-wavelengths, thus broadening the absorption bandwidth. Therefore, perfect absorption in the visible band can be achieved, and perfect absorption in the visible-near infrared can also be achieved.

[0038] A color electrode of the present invention uses a dielectric modulation layer to induce a metal reflection layer to obtain the maximum reflectivity at the central wavelength, while the metal absorption layer can achieve wide-band cut-off outside the reflection band, thereby realizing effective filtering in a specific band and color display. By adjusting the thickness of the dielectric modulation layer, absorption in different bands can be achieved, thus realizing reflection effects of various colors.

[0039] The black and color electrodes and preparation methods of the present invention can prepare electrodes of any color according to requirements compared with traditional electrodes, and can simultaneously maintain a low resistivity.

[0040] The black and color electrodes of the present invention have a simple structure, are easy to prepare, have a low cost, and are suitable for large-area mass production, thus greatly reducing the preparation cost of the black and color electrodes. Therefore, this invention is expected to be widely applied in aspects such as lighting, photovoltaics, displays, and energy storage devices, and make contributions to fields such as China's national economy, social development, science and technology, and national defense construction. Brief Description of the Drawings

[0041] Figure 1 It is a schematic structural diagram of the color electrode of the present invention;

[0042] Figure 2 It is a schematic structural diagram of the black electrode of the present invention;

[0043] Figure 3 It is a preparation flow chart of the black and color electrodes of the present invention;

[0044] Figure 4 It is the reflection spectrum of the blue electrode in Embodiment 1 of the present invention, where the substrate is silicon, the metal reflection layer is silver, the metal absorption layer is chromium, and the dielectric regulation layer is indium tin oxide.

[0045] Figure 5 It is the reflection spectrum of the green electrode in Embodiment 2 of the present invention, where the substrate is K9, the metal reflection layer is aluminum, the metal absorption layer is chromium, and the dielectric regulation layer is indium tin oxide.

[0046] Figure 6The reflection spectrum of the red electrode in Embodiment 3 of the present invention, where the substrate is PET, the metal reflection layer is silver, the metal absorption layer is chromium, and the dielectric regulation layer is indium tin oxide.

[0047] Figure 7 The reflection spectrum and absorption spectrum of the black electrode in Embodiment 4 of the present invention, where the substrate is K9, the metal reflection layer is chromium, the metal absorption layer is chromium, the dielectric regulation layer is indium tin oxide, and the antireflection layer is indium tin oxide.

[0048] Figure 8 The reflection spectrum and absorption spectrum of the black electrode in Embodiment 5 of the present invention, where the substrate is K9, the metal reflection layer is aluminum, the metal absorption layer is chromium, the dielectric regulation layer is indium tin oxide, and the antireflection layer is indium tin oxide. Detailed implementation manners

[0049] The present invention will be described in detail below with reference to the accompanying drawings.

[0050] As Figure 1 shown, a color electrode is composed of a substrate 1 and multiple layers of thin films 2 - 5. The material of the substrate 1 is not limited, and glass materials such as K9, fused quartz, and float glass can be selected, semiconductor materials such as silicon and gallium arsenide can also be selected, plastic materials such as PET, PC, and PI can also be selected, and alloy materials such as stainless steel can also be selected. The bottommost thin film in the above-mentioned multiple layers of thin films is the metal reflection layer 2, and the thickness of this layer should be greater than or equal to 100 nm to block the incident light from transmitting into the substrate; above the metal reflection layer 2 is the dielectric regulation layer 3 with a thickness of 40 nm - 500 nm; above the dielectric regulation layer 3 is the metal absorption layer 4 with a thickness of 4 - 30 nm; above the metal absorption layer 4 is the antireflection layer 5, which can be composed of a single layer or a double layer. The single layer is 40 - 300 nm, and the thicknesses of the double layer are 30 - 300 nm and 30 - 300 nm respectively. The metal reflection layer can select highly reflective metal materials such as silver and aluminum; the metal absorption layer can select highly absorptive metal materials such as chromium and titanium. The metal reflection layer of the present invention is preferably silver, and the metal absorption layer is preferably chromium. The dielectric regulation layer and the antireflection layer can select transparent conductive materials such as indium tin oxide thin films; both the conductive dielectric layer and the antireflection layer of the present invention are preferably indium tin oxide.

[0051] As Figure 2As shown in the figure, a black electrode is composed of a substrate 1 and multiple layers of thin films 2-4. There is no restriction on the material of the substrate 1. Glass materials such as K9, fused quartz, and float glass can be selected. Semiconductor materials such as silicon and gallium arsenide can also be selected. Plastic materials such as PET, PC, and PI can also be selected. Alloy materials such as stainless steel can also be selected. The bottommost thin film of the multiple layers of thin films is a metal reflection layer 2, and the thickness of this layer should be greater than 100 nm to block the incident light from transmitting into the substrate. Above the metal reflection layer 2 is a dielectric modulation layer-metal absorption layer stack 3. The innermost dielectric modulation layer is arranged closely adjacent to the metal reflection layer, and the outermost metal absorption layer is arranged closely adjacent to the antireflection layer. The single-layer thickness of the dielectric modulation layer is 10 nm - 300 nm, and the single-layer thickness of the metal absorption layer is 5 nm - 50 nm. Above the dielectric modulation layer-metal absorption layer stack 3 is an antireflection layer 4, which can be composed of a single layer or a double layer. The single layer is 40 - 300 nm, and the thicknesses of the double layers are 30 - 300 nm and 30 - 300 nm respectively. The metal reflection layer can select highly reflective metal materials such as silver and aluminum, and the metal absorption layer can select highly absorptive metal materials such as chromium and titanium. In the present invention, the metal reflection layer is preferably silver, and the dielectric modulation layer-metal absorption layer stack is preferably an indium tin oxide-chromium stack. The antireflection layer can select transparent conductive materials such as indium tin oxide thin films, and the antireflection layer is preferably indium tin oxide.

[0052] A method for preparing a colored or black electrode includes the following steps, as Figure 3 shown:

[0053] 1) According to the requirements such as the bandwidth requirement, absorption rate, and reflectivity of the required electrode, by optimizing the thicknesses of each layer of thin films, a film system that meets the requirements is designed, including the materials, number of layers, and thicknesses of each layer, etc.;

[0054] 2) Put the substrate into an acetone solution and ultrasonicate for 8 minutes, then clean the substrate with ethanol; then put the substrate (substrate) into an ethanol solution and ultrasonicate for 8 minutes, then clean the substrate with deionized water; finally, put the substrate into deionized water and ultrasonicate for 8 minutes, then clean the substrate with deionized water again; obtain the substrate;

[0055] 3) Use vacuum coating technology to deposit each film layer in sequence to obtain a colored or black electrode.

[0056] A black electrode of the present invention is based on an alternating metal-dielectric stack multilayer film structure with upper light transmission and bottom light impermeability, and utilizes the spiral line characteristic of repeated admittance gyration to achieve the low reflection characteristic, that is, the high absorption characteristic, in the visible light band of the black electrode. This multilayer film structure can generate perfect absorption resonances with overlapping multi-wavelengths, thereby broadening the absorption bandwidth. Therefore, perfect absorption in the visible band can be achieved, and perfect absorption in the visible-near infrared can also be achieved.

[0057] In the present invention, a color electrode utilizes a dielectric modulation layer to induce a metal reflection layer to obtain the maximum reflectivity at the central wavelength, while the metal absorption layer can achieve broadband cut-off outside the reflection band, thereby realizing effective filtering in a specific band for color display. By adjusting the thickness of the dielectric modulation layer, absorption in different bands can be achieved, thereby realizing reflection effects of various colors.

[0058] Specific embodiments:

[0059] Example 1: A blue electrode, with an expected absorption bandwidth of 490 nm - 680 nm and an average absorption rate greater than 84.30%; an expected reflection bandwidth of 430 nm - 470 nm and an average reflectivity greater than 71.30%. The reflection spectrum of this blue electrode is as Figure 4 shown. The color coordinates are (0.183, 0.164). The corresponding substrate material is silicon, and the corresponding film materials from the substrate side are silver, indium tin oxide, chromium, indium tin oxide in sequence. The corresponding film thicknesses of each film layer are 100 nm, 98 nm, 11 nm, 70 nm respectively, and the sheet resistance is 43 mΩ / sq.

[0060] Example 2: The green electrode is basically the same as Example 1, and the absorption bandwidth is changed by adjusting the thickness of the film system; the expected absorption bandwidth is 420 nm - 500 nm, 560 nm - 680 nm, and the average absorption rate is above 65.54%, and the reflection bandwidth is 515 nm - 545 nm, and the average reflectivity is greater than 73.64%. The reflection spectrum of this green electrode is as Figure 5 shown. The color coordinates are (0.268, 0.407). The corresponding film materials from the substrate side are silver, indium tin oxide, chromium, indium tin oxide in sequence. The corresponding film thicknesses of each film layer are 100 nm, 105 nm, 11.3 nm, 155 nm respectively, and the sheet resistance is 56 mΩ / sq.

[0061] Example 3: The red electrode is basically the same as Example 1, and the absorption bandwidth is changed by adjusting the thickness of the film system. The expected absorption bandwidth is 400 nm - 600 nm, and the absorption rate at each wavelength is above 92.45%; the expected reflection bandwidth is 620 nm - 660 nm, and the reflectivity at each wavelength is above 75.88%. The reflection spectrum of this red electrode is as Figure 6 shown. The color coordinates are (0.573, 0.331). The corresponding substrate material is PET, and the corresponding film materials from the substrate side are silver, indium tin oxide, chromium, indium tin oxide in sequence. The corresponding film thicknesses of each film layer are 100 nm, 165 nm, 11 nm, 60 nm respectively, and the sheet resistance is 48 mΩ / sq.

[0062] Example 4: The black electrode has an expected absorption bandwidth of 400 nm - 700 nm and an average absorption rate of 94.50%. The reflection spectrum and absorption spectrum of the black electrode are as shown in Figure 7 . The corresponding substrate material is K9, with a total of 6 thin films. The corresponding film materials from the substrate side are silver, indium tin oxide, chromium, indium tin oxide, chromium, indium tin oxide, and the corresponding film thicknesses of each film layer are 100 nm, 172 nm, 24 nm, 70 nm, 14 nm, 62 nm respectively, and the resistance is 50 mΩ / sq.

[0063] Example 5: The black electrode has an expected absorption bandwidth of 400 nm - 700 nm and an average absorption rate of 94.31%. The reflection spectrum and absorption spectrum of the black electrode are as shown in Figure 8 . The corresponding substrate material is K9, with a total of 6 thin films. The corresponding film materials are aluminum, indium tin oxide, chromium, indium tin oxide, chromium, indium tin oxide in sequence, and the corresponding film thicknesses of each film layer are 100 nm, 276 nm, 32 nm, 80 nm, 11 nm, 70 nm respectively, and the sheet resistance is 26 mΩ / sq.

Claims

1. A colored or black electrode, characterized in that, The electrode includes a substrate, on which a metal reflection layer, multiple groups of dielectric modulation layer-metal absorption layer stacks, and an antireflection layer are sequentially provided, and the sheet resistance of each layer is less than or equal to 20 Ω / sq; when there are multiple groups of the stacks, the bottom layer is a dielectric modulation layer and the top layer is a metal absorption layer; The material of the metal reflection layer is silver or aluminum; the material of the metal absorption layer is chromium; the material of the dielectric modulation layer is indium tin oxide; the material of the antireflection layer is indium tin oxide; The thickness of the reflection layer is 100 - 500 nm; the thickness of the metal absorption layer is 4 - 30 nm; the thickness of the dielectric modulation layer is 40 - 500 nm; the thickness of the antireflection layer is 50 - 300 nm The above-mentioned colored or black electrode is optimized by the following optimization method: During optimization, the following evaluation function is used to evaluate the obtained film system parameters: where N is the number of wavelength points, j is the number of film layers, d is the film layer thickness, α, β, and γ are the weights of the spectrum, resistance, and regularization term for the evaluation function, and R target is the spectral target we need to design, and different colors correspond to different Rs target , n is the complex refractive index of the thin film, which is related to the thin film material and the incident wavelength, R represents the spectral data calculated actually and is related to the thickness d and the refractive index n, and ρ all represents the resistance of the entire electrode, which is related to the film layer thickness and the resistance ρ of each layer. ρ1, ρ2, etc. represent the resistances of different film layers.

2. The colored or black electrode according to claim 1, characterized in that, The substrate is selected from K9, fused quartz, float glass, silicon, gallium arsenide, PET, PC, PI material, or stainless steel alloy material.

3. A method for preparing the colored or black electrode according to any one of claims 1 to 2, characterized in that, Including: (1) Optimize and determine the number of film layers, film layer thickness, and film layer materials according to the required electrode color; (2) Clean the substrate; (3) Deposit each film layer sequentially by vacuum coating to obtain the required black or colored electrode; During optimization, the following evaluation function is used to evaluate the obtained film system parameters: Where N is the number of wavelength points, j is the number of film layers, d is the film layer thickness, α, β, and γ are the weights of the spectrum, resistance, and regularization term for the evaluation function, and R target is the spectral target we need to design, and different colors correspond to different Rs target , n is the complex refractive index of the thin film, which is related to the thin film material and the incident wavelength, R represents the spectral data calculated actually, which is related to the thickness d and the refractive index n, and ρ all represents the resistance of the entire electrode, which is related to the film layer thickness and the resistance ρ of each layer. ρ1, ρ2, etc. represent the resistances of different film layers.

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