Preparation method of nano-porous transparent electrode

Abstract

The invention relates to the technical field of transparent electrodes, in particular to a preparation method of a nano-porous transparent electrode, which comprises the following steps of: S1, depositing a layer of aluminum film on a transparent substrate by adopting a magnetron sputtering technology; s2, the substrate with the aluminum film is immersed in an electrochemical cell, the aluminum film serves as an anode, platinum serves as a cathode, and the oxidation process is controlled by adjusting external voltage and operation time; and S3, taking the materials and carrying out post-treatment. And through a two-step oxidation method, the operation time is greatly shortened under the condition of ensuring the uniformity of the holes. A designer can reasonably select the thickness, the roughness and the aperture size of the aluminum film according to application requirements; the electrode with large roughness can be used in the fields of transparent heating, touch control, electromagnetic shielding and the like, the irregular holes can avoid the phenomena of moire patterns, bad diffraction and the like, and meanwhile the aluminum oxide layer can enhance the environmental reliability of the electrode.

Description

Technical Field

[0001] The present invention relates to the technical field of transparent electrodes, and particularly to a preparation method of a nanoporous transparent electrode. Background Art

[0002] Due to the advantages of controllable diameter, high aspect ratio, and economical production method of the porous anodization technology, the prepared porous alumina is considered a potential alternative material for ITO. However, in order to better control the formation of pore diameter, it is usually carried out at low temperature, and the preparation process takes several hours, with low efficiency. Therefore, a fast and simple method is needed to prepare a material with low surface resistance, good transparency, low roughness, and uniform line distribution. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method of a nanoporous transparent electrode to solve the problems raised in the above background art.

[0004] To achieve the above purpose, the present invention provides the following technical solution: A preparation method of a nanoporous transparent electrode, comprising the following steps:

[0005] S1: Deposit a layer of aluminum film on a transparent substrate by using magnetron sputtering technology;

[0006] S2: Immerse the substrate with the aluminum film in an electrochemical cell, with the aluminum film as the anode and platinum as the cathode, and control the oxidation process by adjusting the applied voltage and operation time;

[0007] S3: Take out the material and perform post-treatment.

[0008] Preferably, the thickness of the aluminum film is 50 - 3000 nm.

[0009] Preferably, the transparent substrate is one of glass, PET, PC, PI, PMMA, silicon wafer, ITO, and FTO.

[0010] Preferably, the specific operation of the magnetron sputtering is as follows:

[0011] Substrate preparation: Select a suitable transparent substrate material, thoroughly clean the substrate surface with a cleaning agent to remove oil, dust, and other contaminants, rinse it with deionized water, and dry it with high-purity nitrogen;

[0012] System preparation: Ensure that the magnetron sputtering system is clean and dust-free, and check the working status of all connections and the vacuum pump;

[0013] Load the target: Install the aluminum target on the target position of the magnetron sputtering system;

[0014] Evacuate the air, fix the cleaned transparent substrate on the sample holder, place the sample holder into the vacuum chamber, seal the vacuum chamber, turn on the vacuum pump, and extract the air inside until the desired low pressure level is reached;

[0015] Fill with working gas. While maintaining the vacuum state, fill the vacuum chamber with the working gas;

[0016] Turn on the sputtering power supply. Turn on the magnetron sputtering power supply to generate a radio frequency or direct current magnetic field, ionize the working gas, and the ionized gas ions are accelerated by the electric field to strike the aluminum target, causing aluminum atoms to sputter out;

[0017] Sputtering coating. Adjust the sputtering parameters to achieve the desired deposition rate and aluminum film characteristics. The aluminum atoms fly in the vacuum and deposit on the surface of the transparent substrate to form an aluminum film;

[0018] Monitoring and adjustment. During the sputtering process, monitor the growth of the aluminum film. When necessary, adjust the sputtering parameters. Equipment such as a quartz crystal monitor can be used to control the thickness of the aluminum film;

[0019] Turn off the sputtering power supply and vent the gas. After reaching the expected thickness of the aluminum film, turn off the sputtering power supply, stop filling with the working gas, gradually release the gas in the vacuum chamber, and restore the atmospheric pressure;

[0020] Take out the sample. Open the vacuum chamber, take out the transparent substrate coated with the aluminum film, and operate carefully to avoid scratching or other damage to the surface of the substrate.

[0021] Preferably, the reaction temperature in S2 is -5 to 60 °C. The low temperature can slow down the chemical dissolution rate at the interface between the oxide layer and the electrolyte, balance the Joule heat generated at the bottom of the aluminum oxide during redox, and ensure the structural integrity. The electrochemical device needs to be equipped with a cooling circulation system to control the temperature in the solution.

[0022] Preferably, the electrolyte in S2 is a 3 - 15 wt% sulfuric acid, oxalic acid or phosphoric acid solution. Continuously stir with multiple equally spaced magnetic rotors to maintain the uniformity of the electrolyte composition and disperse the heat generated during the anodization process. The rotational speed of the magnetic rotors is 150 - 300 r / min.

[0023] Preferably, the external voltage for the sulfuric acid system electrolyte is 5V - 20V, for the oxalic acid system is 14 - 40V, and for the phosphoric acid system is 72 - 180V.

[0024] Preferably, in the operation of submerging the substrate in S2, a hanging rack mechanism is used. The hanging rack mechanism includes a top beam plate, on which a rotating shaft is rotatably installed. A driven gear is installed at the top of the rotating shaft. A driving motor is installed beside the rotating shaft. The output end of the driving motor is connected with a driving gear, and the driving gear is meshed and connected with a platinum sheet. At the bottom of the rotating shaft, an upper mounting plate is connected. At both ends of the bottom surface of the upper mounting plate, a hook is arranged respectively, and the hook is connected with a hanging rack.

[0025] The hanging rack includes a central column. The top of the central column is connected with a top plate. On the top surface of the top plate, two hanging rings are arranged. The hanging rings are hung on the hooks. On the bottom side wall of the central column, several side rods are connected. On each side rod, a mounting frame is connected. In the mounting frame, several mounting rods are arranged. On the mounting rods, clamping pieces are arranged.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] A preparation method of a nano-porous transparent electrode proposed by the present invention, through a two-step oxidation method, greatly shortens the operation time while ensuring uniform pores. The designer can reasonably select the thickness, roughness, and pore size of the aluminum film according to application requirements; electrodes with larger roughness can be used in fields such as transparent heating, touch control, and electromagnetic shielding, and irregular pores can avoid phenomena such as moiré patterns and adverse diffraction. At the same time, the alumina layer can enhance the environmental reliability of the electrode. Brief Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of the electrochemical device of the present invention.

[0029] Figure 2 It is a side view of pore formation of the present invention.

[0030] Figure 3 It is a top view of pore formation of the present invention.

[0031] Figure 4 It is a structural diagram of the hanging rack mechanism of the present invention.

[0032] Figure 5 It is a bottom view of the hanging rack mechanism of the present invention.

[0033] Figure 6 It is an enlarged view of A.

[0034] In the figure: substrate 1, aluminum film 2, platinum sheet 3, top beam plate 4, rotating shaft 5, driven gear 6, driving motor 7, driving gear 8, upper mounting plate 9, hook 10, central column 11, top plate 12, hanging ring 13, side rod 14, mounting frame 15, mounting rod 16, clamping piece 17. Detailed Embodiments

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] Please refer to Figures 1 to 6 , the present invention provides a technical solution: a method for preparing a nano-porous transparent electrode, which includes the following steps:

[0037] S1: Deposit a layer of aluminum film on the transparent substrate by magnetron sputtering technology;

[0038] S2: Immerse the substrate with the aluminum film in an electrochemical cell, with the aluminum film as the anode and platinum as the cathode, and control the oxidation process by adjusting the applied voltage and operation time;

[0039] S3: Take the material and perform post-treatment.

[0040] The thickness of the aluminum film is 50 - 3000 nm.

[0041] The transparent substrate is one of glass, PET, PC, PI, PMMA, silicon wafer, ITO, FTO. When selecting the transparent substrate material, the following factors need to be considered:

[0042] Light transmittance: The light transmittance of the substrate should be as high as possible to meet the requirements of the transparent electrode; Heat resistance: The substrate should be able to withstand the high temperature during the electrode preparation process;

[0043] Chemical stability: The substrate should have good chemical stability to prevent chemical changes during manufacturing or use;

[0044] Mechanical properties: The substrate should have a certain mechanical strength and flexibility, especially for flexible electronic devices;

[0045] Surface characteristics: The surface of the substrate should be easy to be functionalized, such as coating, deposition, etc.

[0046] The specific operation of the magnetron sputtering is as follows:

[0047] Substrate preparation, select a suitable transparent substrate material, thoroughly clean the substrate surface with a cleaning agent to remove oil stains, dust and other contaminants, rinse with deionized water, and dry with high-purity nitrogen;

[0048] System preparation, ensure that the magnetron sputtering system (including the vacuum chamber, magnetron target, sample holder, etc.) is clean and dust-free, and check the working status of all connections and the vacuum pump;

[0049] Load the target material and install the aluminum target on the target position of the magnetron sputtering system;

[0050] Evacuate the chamber. Fix the cleaned transparent substrate on the sample holder, place the sample holder into the vacuum chamber, seal the vacuum chamber, turn on the vacuum pump, and extract the air inside the chamber until the desired low pressure level is reached;

[0051] Introduce the working gas. While maintaining the vacuum state, introduce the working gas (usually argon) into the vacuum chamber;

[0052] Target pre-treatment is an optional operation. Before turning on the sputtering power supply, it may be necessary to pre-treat the aluminum target to remove the surface oxide layer;

[0053] Turn on the sputtering power supply. Turn on the magnetron sputtering power supply to generate a radio frequency or direct current magnetic field, ionize the working gas, and the ionized gas ions are accelerated by the electric field to strike the aluminum target, causing aluminum atoms to sputter out;

[0054] Sputtering coating. Adjust the sputtering parameters (such as sputtering power, gas flow rate, working pressure, etc.) to achieve the desired deposition rate and aluminum film characteristics. The aluminum atoms fly in the vacuum and deposit on the surface of the transparent substrate to form an aluminum film;

[0055] Monitoring and adjustment. During the sputtering process, monitor the growth of the aluminum film. Adjust the sputtering parameters if necessary. Equipment such as a quartz crystal monitor can be used to control the thickness of the aluminum film;

[0056] Turn off the sputtering power supply and vent the gas. After reaching the expected aluminum film thickness, turn off the sputtering power supply, stop introducing the working gas, gradually release the gas in the vacuum chamber, and restore the atmospheric pressure;

[0057] Take out the sample. Open the vacuum chamber, take out the transparent substrate coated with the aluminum film, and operate carefully to avoid scratching or other damage to the substrate surface.

[0058] Post-treatment is an optional step. According to needs, post-treat the aluminum film, such as annealing treatment to improve its structure or performance.

[0059] The reaction temperature in S2 is -5 to 60 °C. The low temperature can slow down the chemical dissolution rate at the interface between the oxide layer and the electrolyte, balance the Joule heat generated at the bottom of the aluminum oxide during the redox process, and ensure the structural integrity. The electrochemical device needs to be equipped with a cooling circulation system to control the temperature in the solution.

[0060] The electrolyte in S2 is a 3 - 15 wt% sulfuric acid, oxalic acid, or phosphoric acid solution. Continuously stir with multiple equally spaced magnetic rotors to maintain the uniformity of the electrolyte composition and disperse the heat generated during the anodization process. The rotation speed of the magnetic rotors is 150 - 300 r / min.

[0061] The electrolyte is a sulfuric acid system with an applied voltage of 5V - 20V, an oxalic acid system with an applied voltage of 14 - 40V, and a phosphoric acid system with an applied voltage of 72 - 180V. If the voltage is too small, regular and uniform pores cannot be formed; if the voltage is too high, the pores will change from the nanoscale to the microscale, and even cause the pore skeleton to be discontinuous.

[0062] Principle of nanopore formation:

[0063] Aluminum at the anode dissociates to generate Al under the applied voltage 3+ , and at the same time, a small amount of water molecules dissociate into O 2- or OH - :

[0064] Top beam plate 4Al → Al 3+ + 3e -

[0065] Rotating shaft 5H2O → 2H + + O 2-

[0066] Driven gear 6H2O → H + + OH -

[0067] Subsequently, O 2- or OH - is attracted to the positive potential of the anode to generate Al2O3;

[0068] Top beam plate 42Al 3+ + 3O 2- → Al2O3

[0069] Rotating shaft 52Al 3+ + 3OH - → Al2O3 + 3H +

[0070] During this process, as Al2O3 continues to be generated, the current density drops rapidly;

[0071] H+ will also dissolve alumina to form Al 3+ and H2O:

[0072] Driven gear 6Al2O3 + 6H + → 2Al 3+ + 3H2O

[0073] When the surface layer of Al2O3 is dissolved, pits are formed and grow into fully formed pores, and the pores grow towards the substrate; when the dissolution rate of Al2O3 is the same as the formation rate, the pore size no longer changes.

[0074] In the operation of immersing the substrate in S2, a hanging rack mechanism is used. The hanging rack mechanism includes a top beam plate 4 which can be lifted and lowered. A rotating shaft 5 is rotatably installed on the top beam plate 4. There are multiple rotating shafts 5, and each corresponds to a group of hanging racks. A driven gear 6 is installed at the top of the rotating shaft 5. A driving motor 7 is installed beside the rotating shaft 5. The output end of the driving motor 7 is connected with a driving gear 8. The driving gear 8 is meshed and connected with the platinum sheet 3. A top mounting plate 9 is connected to the bottom of the rotating shaft 5. At both ends of the bottom surface of the top mounting plate 9, there is a hook 10 each. The hook 10 is connected with a hanging rack. The hanging rack includes a central column 11. The top of the central column 11 is connected with a top plate 12. On the top surface of the top plate 12, there are two hanging rings 13. The hanging rings 13 are hung on the hooks 10. On the bottom side wall of the central column 11, several side rods 14 are connected. Each side rod 14 is connected with a mounting frame 15. Several mounting rods 16 are arranged in the mounting frame 15. A clamping member 17 is arranged on the mounting rod 16. When using the hanging rack mechanism, the substrate is correspondingly clamped on the clamping member 17. After it is fully loaded, the hanging rings 13 are hung on the hooks 10. Then the top beam plate 4 descends to immerse the substrate in the electrochemical cell. Control the driving motor 7 to start and drive the driving gear 8 to rotate, so that the lower hanging rack drives the substrate to rotate. The feeding is convenient and beneficial to the reaction.

[0075] Specific Example 1: S1: Using ITO transparent glass as the substrate, sputter a 2000 nm thick aluminum film on its surface. The electrolyte is an aqueous solution of 5 wt% phosphoric acid, the temperature is -4 °C, and the magnetic stirring speed is 200 r / min. Using the aluminum film as the anode and platinum as the cathode, the applied voltage is 80 V (DC), and the operation time is 40 s to form uniform nano-pores on the surface of the aluminum film. S2: In order to expand the pore size, the electrolyte is replaced with an aqueous solution of 7.5 wt% oxalic acid, the temperature is 40 °C, and the magnetic stirring speed is 300 r / min. Using the aluminum film as the anode and platinum as the cathode, the applied voltage is 40 V (DC), and the operation time is 36 min to make the nano-pores on the surface layer develop towards the substrate.

[0076] Specific Example 2: S1: Using ITO transparent glass as the substrate, sputter a 60 nm thick aluminum film on its surface. The electrolyte is an aqueous solution of 5 wt% phosphoric acid, the temperature is -5 °C, and the magnetic stirring speed is 200 r / min. Using the aluminum film as the anode and platinum as the cathode, the applied voltage is 80 V (DC), and the operation time is 20 s to form uniform nano-pores on the surface of the aluminum film. S2: In order to expand the pore size, the electrolyte is replaced with an aqueous solution of 5 wt% oxalic acid, the temperature is 40 °C, and the magnetic stirring speed is 300 r / min. Using the aluminum film as the anode and platinum as the cathode, the applied voltage is 40 V (DC), and the operation time is 4 min to make the nano-pores on the surface layer develop towards the substrate.

[0077] Through a two-step oxidation method, the present invention greatly shortens the operation time while ensuring uniform holes. Designers can reasonably select the thickness, roughness, and pore size of the aluminum film according to application requirements; electrodes with relatively large roughness can be used in fields such as transparent heating, touch control, and electromagnetic shielding, and irregular holes can avoid phenomena such as moiré patterns and adverse diffraction. At the same time, the alumina layer can enhance the environmental reliability of the electrodes.

[0078] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a nanoporous transparent electrode, characterized in that: The following steps are included: S1: Depositing an aluminum film on a transparent substrate using magnetron sputtering technology; S2: Immerse the substrate with the aluminum film in an electrochemical cell, with the aluminum film as the anode and platinum as the cathode, and control the oxidation process by adjusting the applied voltage and operation time; S3: Take the material and perform post-processing.

2. The method for preparing a nanoporous transparent electrode according to claim 1, characterized in that: The thickness of the aluminum film is 50-3000nm.

3. The method for preparing a nanoporous transparent electrode according to claim 1, characterized in that: The transparent substrate is one of glass, PET, PC, PI, PMMA, silicon wafer, ITO and FTO.

4. The method for preparing a nanoporous transparent electrode according to claim 1, characterized in that: The specific operation of the magnetron sputtering is: Substrate preparation: select appropriate transparent substrate material, use cleaning agent to thoroughly clean the substrate surface, remove oil, dust and other contaminants, rinse with deionized water, and blow dry with high-purity nitrogen; System preparation, ensure that the magnetron sputtering system is clean and dust-free, and check the working status of all connections and vacuum pumps; Load the target material and install the aluminum target material on the target position of the magnetron sputtering system; Vacuuming, fixing the cleaned transparent substrate on the sample holder, placing the sample holder into the vacuum chamber, sealing the vacuum chamber, turning on the vacuum pump, and extracting the air in the chamber until the required low pressure level is reached; Filling the working gas, while maintaining the vacuum state, filling the working gas into the vacuum chamber; Turn on the sputtering power supply, turn on the magnetron sputtering power supply, generate a radio frequency or DC magnetic field to ionize the working gas, and the ionized gas ions are accelerated to collide with the aluminum target under the action of the electric field, so that the aluminum atoms are sputtered out; Sputtering coating, adjusting the sputtering parameters to achieve the desired deposition rate and aluminum film properties, aluminum atoms fly in a vacuum and deposit on the surface of a transparent substrate to form an aluminum film; Monitoring and adjustment: During the sputtering process, monitor the growth of the aluminum film and adjust the sputtering parameters if necessary. The thickness of the aluminum film can be controlled by using equipment such as quartz crystal monitors. Turn off the sputtering power supply and vent gas. When the expected aluminum film thickness is reached, turn off the sputtering power supply, stop filling the working gas, gradually vent the gas in the vacuum chamber, and restore the atmospheric pressure. Take out the sample, open the vacuum chamber, and take out the transparent substrate coated with aluminum film. Operate with care to avoid scratching or other damage on the substrate surface.

5. The method for preparing a nanoporous transparent electrode according to claim 1, characterized in that: The reaction temperature in S2 is -5 to 60°C. The low temperature can slow down the chemical dissolution rate at the interface between the oxide layer and the electrolyte, balance the Joule heat generated at the bottom of the aluminum oxide during oxidation and reduction, and ensure the integrity of the structure. The electrochemical device needs to be equipped with a cooling circulation system to control the temperature in the solution.

6. The method for preparing a nanoporous transparent electrode according to claim 1, characterized in that: The electrolyte in S2 is a 3-15wt% sulfuric acid, oxalic acid or phosphoric acid solution, which is continuously stirred by multiple equally spaced magnetic rotors to maintain the uniformity of the electrolyte composition and disperse the heat generated during the anodizing process. The speed of the magnetic rotor is 150-300r / min.

7. The method for preparing a nanoporous transparent electrode according to claim 1, characterized in that: The applied voltage for the sulfuric acid system is 5V-20V, the applied voltage for the oxalic acid system is 14-40V, and the applied voltage for the phosphoric acid system is 72-180V.

8. The method for preparing a nanoporous transparent electrode according to claim 1, characterized in that: The immersion substrate operation in S2 uses a rack mechanism, which includes a top beam plate, a rotating shaft is rotatably mounted on the top beam plate, a driven gear is mounted on the top of the rotating shaft, a driving motor is mounted next to the rotating shaft, an output end of the driving motor is connected to a driving gear, the driving gear is meshed with a platinum sheet, an upper mounting plate is connected to the bottom of the rotating shaft, and a hook is provided at each end of the bottom surface of the upper mounting plate, and the hook is connected to the rack; The hanging rack includes a central column, the top of the central column is connected to a top plate, two hanging rings are arranged on the top surface of the top plate, the hanging rings are hung on hooks, a plurality of side rods are connected to the bottom side wall of the central column, each side rod is connected to a mounting frame, a plurality of mounting rods are arranged in the mounting frame, and a clamp is arranged on the mounting rod.

Images