Biphase tungsten oxide film and preparation method thereof

Abstract

The invention discloses a double-phase tungsten oxide thin film and a preparation method thereof, relates to the technical field of tungsten oxide thin film preparation, and aims to solve the problems that an existing thin film preparation process relates to a plurality of synthesis steps, the cost is high, and large-area expansion is difficult. The method comprises the following steps: selecting a substrate made of a transparent conductive material, cleaning the substrate in deionized water and ethanol in sequence for 10min, and blow-drying the cleaned substrate by using nitrogen; s2, preparing an electrochemical deposition solution; s3, depositing a thin film by an electrochemical method; the substrate in the step S1 is used as a working electrode, the deposition solution in the step S2 is used as a deposition solution, a platinum sheet is used as a counter electrode, Ag / AgCl is used as a reference electrode, the distance between the working electrode and the counter electrode is kept to be 1.5 cm, the current of a deposition surface is set to be-0.1 mA / cm < 2 > to 1.5 mA / cm < 2 > and lasts for 0.1-1 s, then standing is conducted for 0.1-1 s, the current is kept to be 0 mA / cm < 2 > during standing, and circulation is conducted for 500-5000 times.

Description

Technical Field

[0001] The present invention relates to the technical field of tungsten oxide film preparation, and in particular to a dual-phase tungsten oxide film and a preparation method thereof. Background Art

[0002] With the advent of the fourth industrial revolution and the advancement of the technology for building smart interactive devices, tungsten oxide thin films have broad application potential in the fields of optics and electronic devices due to their unique color development reactions (photochromism, electrochromism, gasochromism, and thermochromism). They have been widely used in smart windows, display devices, gas sensors, photocatalytic systems, photoelectric switches, information storage devices, and other fields.

[0003] Generally speaking, crystallinity has a significant effect on the color rendering properties of tungsten oxide films. Crystalline tungsten oxide films usually have a dense atomic structure, thus showing excellent cycle stability and substrate adhesion. Compared with crystalline tungsten oxide, amorphous tungsten oxide has disordered bond lengths and bond angles, and there are a large number of dangling bonds and various structural distortion defects in its distorted structure, and it has a more active electronic structure. Higher atomic disorder and interstitial spacing can serve as a fast channel for ion diffusion, thus showing excellent performance color rendering. However, its adhesion to the substrate is weak, and its cycle stability and service life are usually unsatisfactory due to the highly disordered and unstable structure, which seriously limits the application of the amorphous phase. For many years, researchers have been committed to obtaining crystalline / amorphous dual-phase tungsten oxide films that combine the dual advantages of excellent color rendering properties of the amorphous phase and high stability of the crystalline phase and have high adhesion to the substrate through various preparation schemes.

[0004] Among the common crystalline / amorphous dual-phase tungsten oxide film preparation schemes, magnetron sputtering can be used to make dense films. Its advantages include being able to make films at low temperatures and forming good adhesion between the film and the substrate. Its disadvantages include the need for complex sputtering equipment, high cost, and defects in the prepared film. Usually, the color switching time of such dense films is long. The advantages of vacuum evaporation include easy film formation, excellent film purity, and adjustable crystallinity and microstructure. The disadvantage is that the prepared film is easily absorbed by residual water vapor. The adhesion between the film and the substrate is insufficient, and the film surface is not flat enough. The advantage of the sol-gel method is that the equipment and procedures are simple, which greatly reduces the manufacturing cost of the film. The disadvantage is that there are certain limitations on the materials that can be used in this process, and the adhesion between the obtained film and the substrate is very poor. The advantage of the chemical vapor deposition method is that it can be used to prepare high-quality or doped films on substrates of various shapes. The disadvantage is that complex equipment and high reaction temperatures are required, and the reactants are usually toxic to humans, so the requirements for extraction equipment are very demanding. In addition, the hydrothermal method is also used to prepare dual-phase tungsten oxide with a core-shell structure. Its advantages include the ability to produce high-quality single crystals with adjustable microstructure and particle size, and ion doping can occur directly in the synthesis reaction. The disadvantage is that the high temperature and high pressure reaction conditions require more stringent safety standards and equipment requirements. The common problems of the above schemes are that they all involve multiple synthesis steps and are costly, and difficult to expand on a large area. In addition to the above schemes, electrodeposition is one of the most promising commercial thin film preparation technologies. Its advantages include low cost, high efficiency, and the ability to expand on a large area to prepare amorphous thin films with high color rendering properties. The disadvantage is that it is difficult to directly synthesize crystalline films. Summary of the invention

[0005] In order to solve the above problem, that is, the existing thin film preparation process involves multiple synthesis steps and is costly and difficult to expand on a large area, the present invention proposes a method for preparing a dual-phase tungsten oxide thin film, which includes the following steps: S1: Substrate selection and pretreatment: Select a transparent conductive substrate, wash the substrate in deionized water and ethanol for 10 minutes, and then use nitrogen to treat the washed substrate. Blow dry; S2: preparing electrochemical deposition solution; S3: Electrochemical deposition of thin film; using the substrate in step S1 as the working electrode, the deposition solution in step S2 as the deposition solution, a platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, maintaining the distance between the working electrode and the counter electrode at 1.5 cm, and setting the deposition surface current to -1.5 to -0.1 mA / cm 2 , lasting 0.1-1s, and then resting for 0.1-1s, during which the current is kept at 0mA / cm 2 , cycle 500-5000 times. S4: Post-treatment of the film: The film is rinsed with deionized water and ethanol in sequence to remove impurities attached to the surface of the film, and is blown dry with nitrogen to obtain a crystalline / amorphous dual-phase tungsten oxide film.

[0006] The present invention is further configured as follows: the substrate in step S1 is one of I TO, FTO, PET-ITO, and PI-I TO.

[0007] The present invention is further configured as follows: step S2 includes the following steps: S2-1: Add 10-100 ml of hydrogen peroxide to a beaker, place the beaker in an ice water bath, and stir. While stirring, add 0.3-6 g of tungsten powder and stir until the tungsten powder is completely dissolved. S2-2: adding strong acid to adjust the solution pH to 1-3; S2-3: Continue stirring and insert a platinum sheet to catalytically decompose excess hydrogen peroxide until the solution no longer produces bubbles, then remove the platinum sheet.

[0008] The present invention is further configured as follows: the mass percentage of the hydrogen peroxide in step S2-1 is 20-40%

[0009] The present invention is further configured as follows: the strong acid described in step S2-2 is one of hydrochloric acid (6-12 mol / L), nitric acid (6-12 mol / L) or perchloric acid (6-12.44 mol / L).

[0010] The present invention also provides a dual-phase tungsten oxide film, which is manufactured by the dual-phase tungsten oxide film manufacturing method as described above.

[0011] The beneficial effects of the present invention are:

[0012] The present invention adopts electrochemical deposition method to prepare crystalline / amorphous dual-phase tungsten oxide thin film. Compared with other existing technical solutions, the preparation cost is low, the efficiency is high, the preparation is easy to expand, and the commercialization potential is great. At the same time, the prepared crystalline / amorphous dual-phase tungsten oxide thin film has a wide optical modulation range (ΔT>70%), a long cycle life (the performance is almost not attenuated after the number of cycles in lithium perchlorate propylene carbonate solution>1000 times), and high adhesion to the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The scanning electron microscope image of the dual-phase tungsten oxide film prepared by the present invention is shown.

[0014] Figure 2 The transmission electron microscope image of the dual-phase tungsten oxide film prepared by the present invention is shown.

[0015] Figure 3The Fourier transform diagram of the dual-phase tungsten oxide film prepared by the present invention is shown. DETAILED DESCRIPTION

[0016] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0017] Example 1

[0018] The present invention provides a method for preparing a dual-phase tungsten oxide film, comprising the following steps: S1: Substrate selection and pretreatment: select a substrate made of a transparent conductive material, wash the substrate in deionized water and ethanol for 10 minutes in sequence, and blow dry the washed substrate with nitrogen; S2: preparing electrochemical deposition solution; S3: Electrochemical deposition of thin film; using the substrate in step S1 as the working electrode, the deposition solution in step S2 as the deposition solution, the platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, keeping the distance between the working electrode and the counter electrode at 1.5 cm, and setting the deposition surface current to -1.5 to -0.1 mA / cm 2 , lasting 0.1-1s, and then resting for 0.1-1s, during which the current is kept at 0mA / cm 2 , loop 500-5000 times.

[0019] The substrate in step S1 is one of ITO, FTO, PET-ITO, and PI-ITO.

[0020] Wherein step S2 specifically includes the following steps: S2-1: Add 10-100 ml of hydrogen peroxide to a beaker, place the beaker in an ice water bath, and stir. While stirring, add 0.3-6 g of tungsten powder and stir until the tungsten powder is completely dissolved. S2-2: adding strong acid to adjust the solution pH to 1-3; S2-3: Continue stirring and insert a platinum sheet to catalytically decompose excess hydrogen peroxide until the solution no longer produces bubbles, then remove the platinum sheet.

[0021] The mass percentage of hydrogen peroxide in step S2-1 is 20-40%.

[0022] The strong acid in step S2-2 is one of hydrochloric acid (6-12 mol / L), nitric acid (6-12 mol / L) or perchloric acid (6-12 mol / L).

[0023] Example 2

[0024] This embodiment adopts the preparation method of the dual-phase tungsten oxide film disclosed in Example 1 to prepare a dual-phase tungsten oxide film attached to the surface of a rigid I TO glass, which can be used to construct a rigid device, and includes the following specific steps:

[0025] S1: Select I TO glass sheet (~10Ω / m 2 ) is used as the substrate, and the substrate is cleaned in deionized water and ethanol for 10 minutes in turn, and the cleaned substrate is blown dry with nitrogen.

[0026] S2: preparing electrochemical deposition solution; S2-1: Add 60 ml of hydrogen peroxide to a beaker, place the beaker in an ice water bath, and stir. While stirring, add 1.8 g of tungsten powder and stir until the tungsten powder is completely dissolved; S2-2: add nitric acid (8 mol / L) to adjust the solution pH to 1; S2-3: Continue stirring and insert a platinum sheet to catalytically decompose excess hydrogen peroxide until the solution no longer produces bubbles, then remove the platinum sheet.

[0027] S3: Use the substrate in step S1 as the working electrode, the deposition solution in step S2 as the deposition solution, and a platinum sheet (1×1 cm 2 ) as the counter electrode, the Ag / AgCl electrode as the reference electrode, the distance between the working electrode and the counter electrode was kept at 1.5 cm, and the deposition surface current was set to -1 mA / cm 2 , lasted for 0.5s, and then rested for 0.5s. During the rest period, the current was kept at 0mA / cm 2 , and repeat 1000 times.

[0028] S4: The film is rinsed with deionized water and ethanol in sequence to remove impurities attached to the surface of the film, and is blown dry with nitrogen to obtain a dual-phase tungsten oxide film attached to the rigid ITO glass surface.

[0029] Example 3

[0030] This embodiment adopts the method for preparing the dual-phase tungsten oxide film disclosed in Example 1 to prepare a dual-phase tungsten oxide film attached to the surface of a flexible PET-ITO film, which can be used to construct a flexible device, and includes the following specific steps:

[0031] S1: Select PET-I TO conductive film (~30Ω / m 2 ) is used as the substrate, and the substrate is cleaned in deionized water and ethanol for 10 minutes in turn, and the cleaned substrate is blown dry with nitrogen.

[0032] S2: preparing electrochemical deposition solution; S2-1: Add 100 ml of hydrogen peroxide to a beaker, place the beaker in an ice water bath, and stir. While stirring, add 4 g of tungsten powder and stir until the tungsten powder is completely dissolved. S2-2: add perchloric acid (12.44 mol / L) to adjust the solution pH to 1; S2-3: Continue stirring and insert a platinum sheet to catalytically decompose excess hydrogen peroxide until the solution no longer produces bubbles, then remove the platinum sheet.

[0033] S3: Use the substrate in step S1 as the working electrode, the deposition solution in step S2 as the deposition solution, and a platinum sheet (1×1 cm 2 ) as the counter electrode, the Ag / AgCl electrode as the reference electrode, the distance between the working electrode and the counter electrode was kept at 1.5 cm, and the deposition surface current was set to -0.3 mA / cm 2 , lasting 0.1s, and then resting for 0.1s, during which the current remains at 0mA / cm 2 , and repeat 5000 times.

[0034] S4: The film is rinsed with deionized water and ethanol in sequence to remove impurities attached to the surface of the film, and is blown dry with nitrogen to obtain a dual-phase tungsten oxide film attached to the surface of the flexible PET-ITO film.

[0035] Example 4

[0036] This embodiment adopts the method for preparing the dual-phase tungsten oxide film disclosed in Example 1 to prepare a dual-phase tungsten oxide film attached to the surface of a rigid FTO glass, which can be used for high-temperature annealing and recrystallization, and includes the following specific steps:

[0037] S1: Select FTO glass sheet (~10Ω / m 2 ) is used as the substrate, and the substrate is cleaned in deionized water and ethanol for 10 minutes in turn, and the cleaned substrate is blown dry with nitrogen.

[0038] S2: preparing electrochemical deposition solution; S2-1: Add 60 ml of hydrogen peroxide to a beaker, place the beaker in an ice water bath, and stir. While stirring, add 1.2 g of tungsten powder and stir until the tungsten powder is completely dissolved; S2-2: add nitric acid (12 mol / L) to adjust the solution pH to 1; S2-3: Continue stirring and insert a platinum sheet to catalytically decompose excess hydrogen peroxide until the solution no longer produces bubbles, then remove the platinum sheet.

[0039] S3: Use the substrate in step S1 as the working electrode, the deposition solution in step S2 as the deposition solution, and a platinum sheet (1×1 cm 2) as the counter electrode, the Ag / AgCl electrode as the reference electrode, the distance between the working electrode and the counter electrode was kept at 1.5 cm, and the deposition surface current was set to -1.5 mA / cm 2 , lasted for 0.5s, and then rested for 1s. During the rest period, the current was kept at 0mA / cm 2 , and repeat 1000 times.

[0040] S4: The film is rinsed with deionized water and ethanol in sequence to remove impurities attached to the surface of the film, and is blown dry with nitrogen to obtain a dual-phase tungsten oxide film attached to the rigid FTO glass surface.

[0041] Example 5

[0042] The present invention also provides a dual-phase tungsten oxide film, which is manufactured by the dual-phase tungsten oxide film manufacturing method as described above.

[0043] In summary, the present invention adopts electrochemical deposition method to prepare crystalline / amorphous dual-phase tungsten oxide thin film, which has low preparation cost, high efficiency, easy to expand preparation and great commercial potential compared with other existing technical solutions. At the same time, the prepared crystalline / amorphous dual-phase tungsten oxide thin film has a wide optical modulation range (ΔT>70%), long cycle life (performance is almost not attenuated after the number of cycles in lithium perchlorate propylene carbonate solution>1000 times), and high adhesion to the substrate.

[0044] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0045] In the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0046] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] The term "comprise" or any other similar term is intended to cover a non-exclusive inclusion, such that a process, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, article, or apparatus / device.

[0048] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for preparing a dual-phase tungsten oxide thin film, characterized in that: The following steps are involved: S1: Substrate selection and pretreatment: Select a transparent conductive substrate, wash the substrate in deionized water and ethanol for 10 minutes in sequence, and blow dry the washed substrate with nitrogen; S2: preparing electrochemical deposition solution; S3: Electrochemical deposition of thin film; using the substrate in step S1 as the working electrode, the deposition solution in step S2 as the deposition solution, a platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, maintaining the distance between the working electrode and the counter electrode at 1.5 cm, and setting the deposition surface current to -1.5 to -0.1 mA / cm 2 , lasting 0.1-1s, and then resting for 0.1-1s, during which the current is kept at 0mA / cm 2 , cycle 500-5000 times. S4: Post-treatment of the film: The film is rinsed with deionized water and ethanol in sequence to remove impurities attached to the surface of the film, and is blown dry with nitrogen to obtain a crystalline / amorphous dual-phase tungsten oxide film.

2. The method for preparing a dual-phase tungsten oxide thin film according to claim 1, characterized in that: The substrate in step S1 is one of ITO, FTO, PET-ITO, and PI-ITO.

3. The method for preparing a dual-phase tungsten oxide thin film according to claim 1, characterized in that: Step S2 includes the following steps: S2-1: Add 10-100 ml of hydrogen peroxide to a beaker, place the beaker in an ice water bath, and stir. While stirring, add 0.3-6 g of tungsten powder and stir until the tungsten powder is completely dissolved; S2-2: adding strong acid to adjust the solution pH to 1-3; S2-3: Continue stirring and insert a platinum sheet to catalytically decompose excess hydrogen peroxide until the solution no longer produces bubbles, then remove the platinum sheet.

4. The method for preparing a dual-phase tungsten oxide thin film according to claim 3, characterized in that: The mass percentage of the hydrogen peroxide in step S2-1 is 20-40%.

5. The method for preparing a dual-phase tungsten oxide thin film according to claim 3, characterized in that: The strong acid described in step S2-2 is one of hydrochloric acid (6-12 mol / L), nitric acid (6-12 mol / L) or perchloric acid (6-12.44 mol / L).

6. A dual-phase tungsten oxide film, characterized in that: The dual-phase tungsten oxide film is prepared by the method for preparing the dual-phase tungsten oxide film according to any one of claims 1 to 5.

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