Coating production method, coating and product comprising a coating

Abstract

The present application relates to the field of surface treatment, and particularly relates to a coating preparation method, a coating and a product comprising the coating. The coating preparation method comprises: providing a substrate, placing the substrate in a plasma reactor; and introducing a conductive polymer monomer in gaseous form into the plasma reactor at a flow rate of 100 μL / min to 800 μL / min, and introducing oxygen into the plasma reactor at a flow rate of 20 sccm to 100 sccm, performing plasma discharge at an average power of 10 W to 120 W, so as to deposit a coating on the surface of the substrate. The coating preparation method of the present application does not require a solvent, an oxidant or a catalyst, simplifies the process, has no environmental pressure, and can form a uniform, dense and conductive coating on various substrates such as conductive, insulating and nanostructured substrates, and the like.

Description

Technical Field

[0001] This invention relates to the field of surface treatment, and more particularly to a coating preparation method, a coating, and a product comprising the coating. Background Technology

[0002] Conductive polymers have demonstrated wide and important applications in fields such as flexible electronics, energy storage, biosensing, and photocatalysis due to their unique electrical, optical, and mechanical properties.

[0003] However, traditional methods for preparing conductive polymers often involve multiple steps and require the use of chemical oxidants, catalysts, or electrolytes, generating chemical waste. These methods are not only complex but also pose environmental risks. When preparing conductive polymer films, the poor solubility of conductive polymers in common solvents often results in uneven and rough films with unstable conductivity. Alternatively, they may produce powders that are difficult to process rather than usable films, limiting their applications. Or, they may require a conductive substrate, making it impossible to form films directly on insulating substrates. Or, they may be unable to form uniform, non-agglomerated coatings on substrates that serve as nanostructures. Summary of the Invention

[0004] To address the aforementioned technical problems, embodiments of the present invention provide a coating preparation method, a coating, and a product comprising the coating.

[0005] To achieve the above objectives, one aspect of the present invention relates to a coating preparation method, comprising: providing a substrate, placing the substrate in a plasma reactor; and introducing a gaseous conductive polymer monomer and oxygen into the plasma reactor at a flow rate of 100 μL / min to 800 μL / min, and performing plasma discharge at an average power of 10 W to 120 W to deposit a coating on the surface of the substrate.

[0006] In some embodiments, the plasma discharge is a continuous discharge or a pulsed discharge.

[0007] In some embodiments, the plasma discharge is a pulsed discharge, and the average power of the pulsed discharge is: P = Pcw × D, where D is the pulse duty cycle and Pcw is the pulsed discharge power.

[0008] In some embodiments, the conductive polymer monomer is selected from one or more of aniline and its derivatives, pyrrole and its derivatives, thiophene and its derivatives, furan and its derivatives, thiazole and its derivatives, imidazole and its derivatives, 2,6-quinoline and its derivatives, isothioindene and its derivatives, benzene and its derivatives, naphthalene and its derivatives, biphenyl and its derivatives, terphenyl and its derivatives, pyrene and its derivatives, chamomile and its derivatives, and fluorene and its derivatives.

[0009] In some embodiments, the conductive polymer monomer is selected from one or more of aniline, n-toluidine, meta-toluidine, dimethylaniline, n-methoxyaniline, meta-methoxyaniline, 2,5-dimethoxyaniline, pyrrole, N-methylpyrrole, N-ethylpyrrole, N-phenylpyrrole, N-tolylpyrrole, 3-methylthiophene, methylthiophene, 3-phenylthiophene, 2-phenylthiophene, benzothiophene, 3,4-ethylenedioxythiophene, thieno[3,4-b]thiophene, thieno[3,2-b]thiophene, 1H-thieno[3,4-d]imidazoline-2(3H)-one, furan, thiazole, imidazole, 2,6-quinoline, 5-methylisothioindene, 5,6-dimethylisothioindene, phenylene, and benzyl chamomile ring.

[0010] In some embodiments, the conductive polymer monomer is selected from one or more of aniline, 3,4-ethylenedioxythiophene, and pyrrole.

[0011] In some embodiments, before introducing gaseous conductive polymer monomers into the plasma reactor at a flow rate of 100 μL / min to 800 μL / min and oxygen at a flow rate of 20 sccm to 100 sccm, and performing plasma discharge at an average power of 10 W to 120 W, the method further includes: introducing gaseous conductive polymer monomers into the plasma reactor at a flow rate of 50 μL / min to 400 μL / min and oxygen at a flow rate of 20 sccm to 100 sccm, and performing plasma discharge at a power of 50 W to 600 W and in a continuous discharge manner to form a transition layer on the substrate surface.

[0012] In some embodiments, the method further includes introducing an inert gas, including helium and / or argon, into the plasma reactor at a flow rate of 20 sccm to 100 sccm while simultaneously introducing oxygen into the plasma reactor.

[0013] Another aspect of the present invention relates to a coating prepared according to the method described in the present invention.

[0014] In some embodiments, the electrical conductivity of the coating is 1×10⁻⁶. -2 S / cm up to 9×10 -2 S / cm.

[0015] In some embodiments, the coating thickness is 600 nm to 800 nm.

[0016] Another aspect of the present invention relates to a product having at least a portion of its surface covered with the coating described herein.

[0017] The coating preparation method of this invention requires no solvent, oxidant or catalyst, simplifies the process, has no environmental impact, and can form uniform, dense and highly conductive coatings on various substrates such as conductive, insulating and nanostructured materials.

[0018] Where technical conditions permit, the technical solutions of the various embodiments in this application can be combined in any way. Detailed Implementation

[0019] One aspect of this invention relates to a coating preparation method, comprising: providing a substrate, placing the substrate in a plasma reactor; and introducing a gaseous conductive polymer monomer and oxygen into the plasma reactor at a flow rate of 100 μL / min to 800 μL / min, and performing plasma discharge at an average power of 10 W to 120 W to deposit a coating on the surface of the substrate.

[0020] The coating preparation method of this invention uses plasma-enhanced chemical vapor deposition (PECVD) to deposit a conductive polymer coating on the substrate surface, which is a dry, one-step process.

[0021] Specifically, the coating preparation method of this invention can be carried out in a vacuum or atmospheric pressure environment by using plasma containing active species such as high-energy electrons, ions, free radicals, and photons to excite the vapor of conductive polymer monomers, causing them to decompose, rearrange, and repolymerize, thereby depositing a conductive polymer coating on the substrate surface. When preparing conductive polymer coatings by PECVD, no solvents, oxidants, or catalysts are required, avoiding the post-processing complexity and solvent pollution problems of wet chemical polymerization, thus simplifying the process and eliminating environmental concerns.

[0022] PECVD has no special requirements for the substrate. It allows for the deposition of uniform, dense, and highly conductive polymer coatings on various substrates. Substrates can include conductive substrates, insulating substrates, and nanostructures, such as silicon, glass, metals, plastics, carbon nanotubes, and titanium dioxide nanotubes. Substrates can also be used for battery electrodes, sensors, and solar cells.

[0023] The plasma reactor can be any plasma reaction apparatus suitable for the present invention. For example, the plasma reactor can have a rotating body-shaped chamber or a cubic chamber with a volume of 50 L to 1000 L for the plasma reaction to take place.

[0024] The conductive polymer monomer can be a monomer that undergoes a plasma-initiated polymerization reaction in a plasma reactor to form a conductive polymer. The conductive polymer monomer may have an aromatic conjugated structure, and after reaction in the plasma reactor, it can polymerize into a conductive polymer with linear conjugated double bonds, thereby endowing the coating with excellent electrical and optical properties.

[0025] In this embodiment of the invention, plasma discharge is performed with an average power of 10 W to 120 W to reduce the bombardment of conductive polymer monomers by high-energy particles in the plasma, prevent high-energy particles in the plasma from destroying the aromatic conjugated structure of the conductive polymer monomers, and generate a highly cross-linked, three-dimensional network-like cross-linked polymer coating, rather than an ideal linear conjugated chain polymer coating. This can preserve the original π-conjugated system structure of the monomers to the maximum extent, thereby improving the electrical and optical properties of the finally deposited coating.

[0026] A coating is deposited by introducing gaseous conductive polymer monomers into a plasma reactor at a flow rate of 100 μL / min to 800 μL / min and oxygen at a flow rate of 20 sccm to 100 sccm. Oxygen can be used as a dopant gas to achieve in-situ doping of the conductive polymer coating, thereby improving the conductivity of the coating deposited on the substrate surface.

[0027] Thus, in this embodiment of the application, by selecting an average power of 10 W to 120 W for plasma discharge and introducing oxygen as a dopant gas during the deposition process, coatings with good electrical and optical properties are deposited on various substrates by PECVD.

[0028] In this embodiment of the invention, unless otherwise specifically indicated, the numerical range may include any sub-range therein. For example, 10 W to 120 W may include 20 W to 110 W, 30 W to 100 W, 40 W to 90 W, 50 W to 80 W, 60 W to 70 W, and so on.

[0029] In some embodiments, the plasma discharge is a continuous discharge or a pulsed discharge.

[0030] The discharge power of continuous discharge can range from 10 W to 300 W, and the discharge time can range from 60 seconds to 36,000 seconds. The pulse duty cycle of pulse discharge can range from 0.1% to 90%, the pulse frequency can range from 10 Hz to 500 Hz, the discharge power can range from 10 W to 400 W, and the discharge time can range from 200 seconds to 36,000 seconds.

[0031] In some embodiments, the plasma discharge is a pulsed discharge, and the average power of the pulsed discharge is: P = Pcw × D, where D is the pulse duty cycle and Pcw is the pulsed discharge power.

[0032] Plasma discharge methods can be electrodeless discharge (such as radio frequency inductively coupled discharge, microwave discharge), single-electrode discharge (such as corona discharge, plasma jet formed by unipolar discharge), two-electrode discharge (such as dielectric barrier discharge, radio frequency glow discharge of bare electrodes), and multi-electrode discharge (such as discharge using a floating electrode as the third electrode).

[0033] In some embodiments, the conductive polymer monomer is selected from one or more of aniline and its derivatives, pyrrole and its derivatives, thiophene and its derivatives, furan and its derivatives, thiazole and its derivatives, imidazole and its derivatives, 2,6-quinoline and its derivatives, isothioindene and its derivatives, benzene and its derivatives, naphthalene and its derivatives, biphenyl and its derivatives, terphenyl and its derivatives, pyrene and its derivatives, chamomile and its derivatives, and fluorene and its derivatives.

[0034] In some embodiments, the conductive polymer monomer is selected from one or more of aniline, n-toluidine, meta-toluidine, dimethylaniline, n-methoxyaniline, meta-methoxyaniline, 2,5-dimethoxyaniline, pyrrole, N-methylpyrrole, N-ethylpyrrole, N-phenylpyrrole, N-tolylpyrrole, 3-methylthiophene, methylthiophene, 3-phenylthiophene, 2-phenylthiophene, benzothiophene, 3,4-ethylenedioxythiophene, thieno[3,4-b]thiophene, thieno[3,2-b]thiophene, 1H-thieno[3,4-d]imidazoline-2(3H)-one, furan, thiazole, imidazole, 2,6-quinoline, 5-methylisothioindene, 5,6-dimethylisothioindene, phenylene, and benzyl chamomile ring.

[0035] In some embodiments, the conductive polymer monomer is selected from one or more of aniline, 3,4-ethylenedioxythiophene, and pyrrole.

[0036] In some embodiments, before introducing gaseous conductive polymer monomers into the plasma reactor at a flow rate of 100 μL / min to 800 μL / min and oxygen at a flow rate of 20 sccm to 100 sccm, and performing plasma discharge at an average power of 10 W to 120 W, the method further includes: introducing gaseous conductive polymer monomers into the plasma reactor at a flow rate of 50 μL / min to 400 μL / min and oxygen at a flow rate of 20 sccm to 100 sccm, and performing plasma discharge at a power of 50 W to 600 W and in a continuous discharge manner to form a transition layer on the substrate surface.

[0037] The continuous discharge time used to form the transition layer can be from 60 seconds to 2400 seconds.

[0038] Forming a transition layer on the substrate surface and then depositing a coating on the transition layer can help improve the adhesion of the coating to the substrate surface.

[0039] In some embodiments, before introducing gaseous conductive polymer monomers and oxygen into the plasma reactor at a flow rate of 100 μL / min to 800 μL / min and a flow rate of 20 sccm to 100 sccm, and performing plasma discharge at an average power of 10 W to 120 W, gaseous conductive polymer monomers and oxygen may be introduced into the plasma reactor at a flow rate of 50 μL / min to 400 μL / min and a flow rate of 20 sccm to 100 sccm, and the discharge is performed at a discharge power of 10 W to 500 W, a pulse frequency of 10 Hz to 500 Hz, and a pulse duty cycle of 0.1% to 90% for 60 seconds to 2400 seconds to form a transition layer on the substrate surface.

[0040] In some embodiments, the method further includes introducing an inert gas, including helium and / or argon, into the plasma reactor at a flow rate of 20 sccm to 100 sccm while simultaneously introducing oxygen into the plasma reactor.

[0041] Inert gases can react with some oxygen through plasma discharge to form plasma, which together initiates plasma polymerization reactions in the plasma reactor.

[0042] The substrate can be placed in the plasma reactor chamber, evacuated to 10 mTorr to 200 mTorr, and at least one of helium, argon, and oxygen can be introduced. Conductive polymer monomers are introduced into an evaporator at a flow rate of 10 μL / min to 2000 μL / min for vaporization. After vaporization, the vaporized monomers are introduced into a plasma reactor chamber, where an RF power supply is activated for discharge, and plasma chemical vapor deposition is performed to deposit a coating on the substrate surface. Turn off the plasma discharge for deposition, introduce clean compressed air or inert gas into the plasma reactor chamber to restore the chamber to normal pressure, open the chamber, and remove the substrate.

[0043] Another aspect of the present invention relates to a coating prepared according to the method described in the present invention.

[0044] The coatings of this invention are prepared according to the method described in this invention. As mentioned above, they do not require solvents, oxidants, or catalysts, simplify the process, have no environmental impact, and can be deposited on various substrates such as conductive, insulating, and nanostructured substrates. They are uniform, dense, and have good conductivity, etc.

[0045] In some embodiments, the electrical conductivity of the coating is 1×10⁻⁶. -2S / cm up to 9×10 -2 S / cm.

[0046] In some embodiments, the coating thickness is 600 nm to 800 nm.

[0047] Another aspect of the present invention relates to a product having at least a portion of its surface covered with the coating described herein.

[0048] Products may include optical components and consumer electronics housings made of various substrates such as plastics and metals, for example, battery electrodes, sensors, and solar cells.

[0049] The technical solutions of the present invention can facilitate the formation of uniform, dense, and highly conductive coatings on various substrates, such as conductive, insulating, and nanostructured materials, as plating surfaces without the use of solvents, oxidants, or catalysts. The process is simplified and there is no environmental pressure.

[0050] The embodiments of the present invention will be illustrated below with specific examples. These examples are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0051] Example

[0052] Test Method Description

[0053] Coating thickness testing: The coating thickness was measured using a Filmetrics F20-UV thin film thickness measuring instrument from the United States. The instrument was calibrated using a standard calibration sheet before testing.

[0054] Coating conductivity test: The RTS-8 four-probe tester was used for testing.

[0055] Example 1

[0056] 1) Vacuuming: Place the Si wafer and glass on the substrate support of the plasma reactor chamber (600 L volume), evacuate to 120 mTorr, and set the chamber temperature to 50°C. o C; 2) Pretreatment: Maintain the chamber pressure at 120 mTorr, helium flow rate at 60 sccm, oxygen flow rate at 60 sccm, and introduce aniline into the evaporator at a flow rate of 120 μL / min. Turn on continuous plasma discharge with a discharge power of 300 W and continue discharging for 600 seconds to pretreat the substrate in order to deposit a transition layer on the substrate surface. 3) Coating deposition: After pretreatment, aniline was introduced into the evaporator at a flow rate of 240 μL / min, and then at 120°C... oAfter being vaporized at the vaporization temperature of C, the gas is introduced into the plasma chamber. The chamber pressure is maintained at 120 mTorr, the helium flow rate is maintained at 60 sccm, and the oxygen flow rate is maintained at 60 sccm. The plasma pulse discharge is activated, and a coating is formed on the substrate surface by plasma chemical vapor deposition. The pulse duty cycle is 10%, the pulse frequency is 250 Hz, the pulse discharge power is 100 W (average power 10 W), and the reaction time is 7200 seconds. 4) Coating test: After the coating is completed, compressed air is filled to restore the chamber to normal pressure, the coated substrate is taken out, the film thickness on the Si wafer is tested, and the coating conductivity on the glass is measured. The results are listed in Table 1 below.

[0057] Example 2

[0058] The coating was prepared in the same manner as in Example 1, except that in step 3), the pulse duty cycle was 50%, the pulse frequency was 250 Hz, and the pulse discharge power was 120 W (average power 60 W).

[0059] Example 3

[0060] The coating was prepared in the same manner as in Example 1, except that in step 3), the pulse duty cycle was 80%, the pulse frequency was 250 Hz, and the pulse discharge power was 150 W (average power 120 W).

[0061] Example 4

[0062] The coating was prepared in the same manner as in Example 1, except that 3,4-ethylenedioxythiophene was used instead of aniline, and the pulse duty cycle in step 3) was 40%, the pulse frequency was 250 Hz, and the pulse discharge power was 80 W (average power 32 W).

[0063] Example 5

[0064] The coating was prepared in the same manner as in Example 1, except that 3,4-ethylenedioxythiophene was used instead of aniline, the helium flow rate was 30 sccm and the oxygen flow rate was 90 sccm in steps 2) and 3), and the pulse duty cycle was 40%, the pulse frequency was 250 Hz and the pulse discharge power was 80 W (average power 32 W) in step 3).

[0065] Example 6

[0066] The coating was prepared in the same manner as in Example 1, except that pyrrole was used instead of aniline, the helium flow rate was 100 sccm and the oxygen flow rate was 20 sccm in steps 2) and 3), and the pulse duty cycle was 50%, the pulse frequency was 250 Hz and the pulse discharge power was 120 W (average power 60 W) in step 3).

[0067] Example 7

[0068] The coating was prepared in the same manner as in Example 1, except that in step 2), the helium flow rate was 20 sccm, the oxygen flow rate was 100 sccm, and 3,4-ethylenedioxythiophene and pyrrole were simultaneously introduced into the evaporator at a flow rate of 60 μL / min and 60 μL / min, respectively. In step 3), 3,4-ethylenedioxythiophene and pyrrole were simultaneously introduced into the evaporator at a flow rate of 120 μL / min and 120 μL / min, respectively. The pulse duty cycle was 40%, the pulse frequency was 250 Hz, and the pulse discharge power was 130 W (average power 52 W).

[0069] Comparative Example 1

[0070] The coating was prepared in the same manner as in Example 1, except that in step 3), the pulse duty cycle was 20%, the pulse frequency was 250 Hz, and the pulse discharge power was 30 W (average power 6 W).

[0071] Comparative Example 2

[0072] The coating was prepared in the same manner as in Example 1, except that in step 3), the pulse duty cycle was 60%, the pulse frequency was 250 Hz, and the pulse discharge power was 250 W (average power 150 W).

[0073] Comparative Example 3

[0074] The coating was prepared in the same manner as in Example 1, except that in step 3), the pulse duty cycle was 80%, the pulse frequency was 250 Hz, and the pulse discharge power was 250 W (average power 200 W).

[0075] Comparative Example 4

[0076] The coating was prepared in the same manner as in Example 1, except that 3,4-ethylenedioxythiophene was used instead of aniline, the helium flow rate was 120 sccm and the oxygen flow rate was 0 sccm in steps 2) and 3), and the pulse duty cycle was 40%, the pulse frequency was 250 Hz and the pulse discharge power was 80 W (average power 32 W) in step 3).

[0077] Comparative Example 5

[0078] The coating was prepared in the same manner as in Example 1, except that 3,4-ethylenedioxythiophene was used instead of aniline, the helium flow rate was 110 sccm and the oxygen flow rate was 10 sccm in steps 2) and 3), and the pulse duty cycle was 40%, the pulse frequency was 250 Hz and the pulse discharge power was 80 W (average power 32 W) in step 3).

[0079] Comparative Example 6

[0080] The coating was prepared in the same manner as in Example 1, except that 3,4-ethylenedioxythiophene was used instead of aniline, the helium flow rate was 0 sccm and the oxygen flow rate was 120 sccm in steps 2) and 3), and the pulse duty cycle was 40%, the pulse frequency was 250 Hz and the pulse discharge power was 80 W (average power 32 W) in step 3).

[0081] Table 1. Test results of coating thickness and conductivity in Examples 1-7 and Comparative Examples 1-6

[0082] As can be seen from Table 1 above, compared with Comparative Examples 1, 2, and 3, the conductivity of Examples 1, 2, and 3 first increases and then decreases with increasing average power. When the average power is low, increasing the average power is beneficial for the deposition of a dense coating of conductive polymer monomers on the substrate surface. Further increasing the average power increases the bombardment of the conductive polymer monomers by the plasma, and the high-energy particles in the plasma destroy the aromatic conjugated structure in the conductive polymer monomers, resulting in a decrease in the coating conductivity.

[0083] Compared with Comparative Examples 4, 5, and 6, Examples 4 and 5 show that increasing the oxygen flow rate initially increases the conductivity of the coating, then decreases. Oxygen acts as a dopant in the PECVD coating process, which is beneficial for improving the conductivity of the coating. However, excessive oxygen as a dopant cannot continuously improve the conductivity of the coating; instead, it etches the coating and reduces its conductivity.

[0084] As can be seen from Examples 1 to 7, the selected conductive polymer monomers exhibit excellent conductivity under suitable process conditions: a conductive polymer monomer flow rate of 100 μL / min to 800 μL / min, an oxygen flow rate of 20 sccm to 100 sccm, and an average power of 10 W to 120 W.

[0085] The various specific embodiments described above are for illustrative purposes only and do not represent the entirety of the invention. Any modifications made by those skilled in the art within the scope of the basic technical concept of this invention are within the protection scope of this invention.

Claims

1. A coating preparation method, characterized in that, include: A substrate is provided, and the substrate is placed in a plasma reactor; as well as A conductive polymer monomer in gaseous form is introduced into the plasma reactor at a flow rate of 100 μL / min to 800 μL / min, and oxygen is introduced as a dopant gas at a flow rate of 20 sccm to 100 sccm. Plasma discharge is performed at an average power of 10 W to 120 W to deposit a coating on the substrate surface.

2. The method according to claim 1, characterized in that, The plasma discharge is either a continuous discharge or a pulsed discharge.

3. The method according to claim 2, characterized in that, The plasma discharge is a pulsed discharge, and the average power of the pulsed discharge is: P=Pcw×D, where D is the pulse duty cycle and Pcw is the pulsed discharge power.

4. The method according to claim 1, characterized in that, The conductive polymer monomer is selected from one or more of aniline and its derivatives, pyrrole and its derivatives, thiophene and its derivatives, furan and its derivatives, thiazole and its derivatives, imidazole and its derivatives, 2,6-quinoline and its derivatives, isothioindene and its derivatives, benzene and its derivatives, naphthalene and its derivatives, biphenyl and its derivatives, terphenyl and its derivatives, pyrene and its derivatives, chamomile ring and its derivatives, and fluorene and its derivatives.

5. The method according to claim 4, characterized in that, The conductive polymer monomer is selected from one or more of the following: aniline, n-toluidine, meta-toluidine, dimethylaniline, n-methoxyaniline, meta-methoxyaniline, 2,5-dimethoxyaniline, pyrrole, N-methylpyrrole, N-ethylpyrrole, N-phenylpyrrole, N-tolylpyrrole, 3-methylthiophene, methylthiophene, 3-phenylthiophene, 2-phenylthiophene, benzothiophene, 3,4-ethylenedioxythiophene, thieno[3,4-b]thiophene, thieno[3,2-b]thiophene, 1H-thieno[3,4-d]imidazoline-2(3H)-one, furan, thiazole, imidazole, 2,6-quinoline, 5-methylisothioindene, 5,6-dimethylisothioindene, phenylene, and benzyl chamomile ring.

6. The method according to claim 5, characterized in that, The conductive polymer monomer is selected from one or more of aniline, 3,4-ethylenedioxythiophene, and pyrrole.

7. The method according to claim 1, characterized in that, Before introducing gaseous conductive polymer monomers into the plasma reactor at a flow rate of 100 μL / min to 800 μL / min and oxygen at a flow rate of 20 sccm to 100 sccm, and performing plasma discharge at an average power of 10 W to 120 W, the method further includes: The conductive polymer monomer in gaseous form is introduced into the plasma reactor at a flow rate of 50 μL / min to 400 μL / min, and oxygen is introduced at a flow rate of 20 sccm to 100 sccm. Plasma discharge is performed at a power of 50 W to 600 W and in a continuous discharge manner to form a transition layer on the surface of the substrate.

8. The method according to claim 7, characterized in that, The method further includes introducing an inert gas, including helium and / or argon, into the plasma reactor at a flow rate of 20 sccm to 100 sccm while simultaneously introducing oxygen into the plasma reactor.

9. A coating, characterized in that, Prepared by any one of claims 1-8.

10. The coating according to claim 9, characterized in that, The electrical conductivity of the coating is 1×10⁻⁶. -2 S / cm up to 9×10 -2 S / cm.

11. The coating according to claim 9, characterized in that, The coating has a thickness of 600 nm to 800 nm.

12. A product characterized in that, At least a portion of the surface of the product has the coating as described in any one of claims 9-11.

Images