阅读说明：本技术 一种导电ZnO薄膜及其制备方法 (Conductive ZnO film and preparation method thereof ) 是由 陈志� 汪洁 唐正 马在飞 于 2020-12-24 设计创作，主要内容包括：本发明涉及导电薄膜技术领域,尤其涉及一种导电ZnO薄膜及其制备方法。本发明提供的制备方法,包括以下步骤：将醋酸锌、乙醇胺和二甲氧基乙醇混合,得到醋酸锌前驱体溶胶；将醋酸锌前驱体溶胶在透明基板上成膜,得到醋酸锌凝胶膜；将醋酸锌凝胶膜进行热处理,得到第一层ZnO薄膜；重复所述成膜和热处理的过程1～5次,得到多层堆叠的ZnO薄膜；将所述多层堆叠的ZnO薄膜进行紫外光辐照,得到导电ZnO薄膜。根据实施例的记载,利用本发明所述的制备方法制备得到的导电ZnO薄膜的电阻率与AZO有相当接近的电阻率,同时在红外和近红外光区具有较好的透射率,可以用作红外和近红外的探测器以及太阳能电池器件的透明电极材料。(The invention relates to the technical field of conductive thin films, in particular to a conductive ZnO thin film and a preparation method thereof. The preparation method provided by the invention comprises the following steps: mixing zinc acetate, ethanolamine and dimethoxyl ethanol to obtain zinc acetate precursor sol; forming a film on the zinc acetate precursor sol on a transparent substrate to obtain a zinc acetate gel film; carrying out heat treatment on the zinc acetate gel film to obtain a first ZnO film; repeating the film forming and heat treatment processes for 1-5 times to obtain a multilayer stacked ZnO film; and carrying out ultraviolet irradiation on the multilayer stacked ZnO film to obtain the conductive ZnO film. According to the description of the embodiment, the resistivity of the conductive ZnO thin film prepared by the preparation method disclosed by the invention is quite close to that of AZO, and meanwhile, the conductive ZnO thin film has better transmissivity in infrared and near-infrared regions, and can be used as a transparent electrode material of infrared and near-infrared detectors and solar cell devices.)

1. A preparation method of a conductive ZnO film is characterized by comprising the following steps:

mixing zinc acetate, ethanolamine and dimethoxyl ethanol to obtain zinc acetate precursor sol;

forming a film on the zinc acetate precursor sol on a transparent substrate to obtain a zinc acetate gel film;

carrying out heat treatment on the zinc acetate gel film to obtain a first ZnO film;

sequentially repeating the film forming and heat treatment processes for 1-5 times to obtain a multilayer stacked ZnO film;

and carrying out ultraviolet irradiation on the multilayer stacked ZnO film to obtain the conductive ZnO film.

2. The preparation method according to claim 1, wherein the ratio of the zinc acetate to the ethanolamine to the dimethoxyethanol is (1-2) g: (200-300) μ L: (10-25) mL.

3. The method of claim 1, wherein the mixing is performed under stirring;

the relative humidity of the mixing is 15-30%, the temperature is 15-40 ℃, and the time is 8-12 h.

4. The method according to claim 1, wherein the film is formed at a relative humidity of 15 to 30% and a temperature of 15 to 40 ℃.

5. The method according to claim 1, wherein the heat treatment is carried out at a temperature of 240 to 360 ℃ for 30 to 60 min.

6. The method of claim 1, wherein the ultraviolet light irradiation is performed in an anhydrous and oxygen-free environment.

7. The method of claim 1 or 6, wherein the UV irradiation has an effective power of 60W, a wavelength of 250 to 396nm, and a time of 5 to 60 min.

8. The production method according to claim 1, further comprising cleaning the transparent substrate before forming the film on the transparent substrate;

the cleaning is to place the transparent substrate in an ultra-clean space and blow air current with the relative humidity of 15-30%;

the air flow has an air volume of 500-3000 m³/h。

9. The conductive ZnO film prepared by the preparation method of any one of claims 1 to 8, wherein the number of the conductive ZnO films is 1 to 6.

10. The conductive ZnO film of claim 9, wherein the conductive ZnO film has a total thickness of 20 to 150 nm;

each layer is 15-35 nm thick independently;

the total thickness of the conductive ZnO film is larger than the thickness of each layer.

Technical Field

The invention relates to the technical field of conductive thin films, in particular to a conductive ZnO thin film and a preparation method thereof.

Background

Transparent Conductive Oxide (TCO) films are a class of special semiconductor optoelectronic materials with high conductivity (high carriers, high mobility and low resistivity) and high transmission in the visible region. Due to these characteristics, the TCO film has been widely used as an important transparent electrode material in various optoelectronic devices, such as light emitting diodes, flat panel displays, solar cells, thin film transistors, transparent heating elements, transparent heat reflective materials, etc. The ZnO-based TCO film has attracted extensive attention in scientific research and industrial fields due to the advantages of low cost, no toxicity, high stability and the like. Intrinsic ZnO is a wide bandgap (about 3.3eV) direct bandgap semiconductor material. The ZnO film after special doping has excellent electrical and optical properties.

For example, Al doping can generate free electrons in ZnO, Al³⁺As a large radius polaron, n-type conductivity in the crystal can be increased, and the optical transmission spectrum of the Al-doped ZnO (AZO) film shows very good transmission rate in a visible wavelength region, which is between 85% and 95%. However, Al-doped ZnO has strong absorption in the infrared region. Therefore, the Al-doped ZnO thin film cannot be used as an electrode material for devices such as high-performance solar cells or infrared photodetectors because of its large infrared absorption loss.

Therefore, there is a need for a conductive ZnO film that can ensure a low resistivity and at the same time, has no absorption in the visible region as well as in the infrared region.

Disclosure of Invention

The invention aims to provide a conductive ZnO film and a preparation method thereof, and the conductive ZnO film prepared by the preparation method has lower resistivity and no absorption in a visible light region and an infrared light region.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of a conductive ZnO film, which comprises the following steps:

mixing zinc acetate, ethanolamine and dimethoxyl ethanol to obtain zinc acetate precursor sol;

forming a film on the zinc acetate precursor sol on a transparent substrate to obtain a zinc acetate gel film;

carrying out heat treatment on the zinc acetate gel film to obtain a first ZnO film;

sequentially repeating the film forming and heat treatment processes for 1-5 times to obtain a multilayer stacked ZnO film;

and carrying out ultraviolet irradiation on the multilayer stacked ZnO film to obtain the conductive ZnO film.

Preferably, the dosage ratio of the zinc acetate, the ethanolamine and the dimethoxyethanol is (1-2) g: (200-300) μ L: (10-25) mL.

Preferably, the mixing is carried out under stirring;

the relative humidity of the mixing is 15-30%, the temperature is 15-40 ℃, and the time is 8-12 h.

Preferably, the relative humidity of the formed film is 15-30%, and the temperature is 15-40 ℃.

Preferably, the temperature of the heat treatment is 240-360 ℃, and the time is 30-60 min.

Preferably, the ultraviolet light irradiation is performed in an anhydrous and oxygen-free environment.

Preferably, the effective power of the ultraviolet irradiation is 60W, the wavelength is 250-396 nm, and the time is 5-60 min.

Preferably, the method further comprises cleaning the transparent substrate before forming the film on the transparent substrate;

the cleaning is to place the transparent substrate in an ultra-clean space and blow air current with the relative humidity of 15-30%;

the air flow has an air volume of 500-3000 m³/h。

The invention also provides the conductive ZnO film prepared by the preparation method of the technical scheme, which is characterized in that the number of the conductive ZnO films is 1-6.

Preferably, the total thickness of the conductive ZnO film is 20-150 nm;

each layer is 15-35 nm thick independently;

the total thickness of the conductive ZnO film is larger than the thickness of each layer.

The invention provides a preparation method of a conductive ZnO film, which comprises the following steps: mixing zinc acetate, ethanolamine and dimethoxyl ethanol to obtain zinc acetate precursor sol; forming a film on the zinc acetate precursor sol on a transparent substrate to obtain a zinc acetate gel film; carrying out heat treatment on the zinc acetate gel film to obtain a first ZnO film; sequentially repeating the film forming and heat treatment processes for 1-5 times to obtain a multilayer stacked ZnO film; and carrying out ultraviolet irradiation on the multilayer stacked ZnO film to obtain the conductive ZnO film. According to the invention, a sol-gel process is adopted, a zinc acetate gel film obtained after film formation is controlled, the zinc acetate gel is subjected to heat treatment, multiple deposition film formation and annealing are carried out, a multilayer stacked ZnO film is obtained, more crystal boundaries are introduced, residual organic matters in the film are finally introduced into the film by ultraviolet induction decomposition, and decomposed matters enter the crystal boundaries to realize the self-doping of ZnO, so that the ZnO semiconductor film is converted into the ZnO conductive film. According to the description of the embodiment, the resistivity of the conductive ZnO thin film prepared by the preparation method disclosed by the invention is quite close to that of AZO, and meanwhile, the conductive ZnO thin film has better transmissivity in infrared and near-infrared regions, is better than that of ITO and AZO conductive thin films, and can be used as transparent electrode materials of infrared and near-infrared detectors and solar cell devices.

Drawings

FIG. 1 shows the absorption coefficients of ZnO films obtained in comparative example 1 and comparative example 2 at different energies;

FIG. 2 is a graph showing the change of the film refractive index and extinction coefficient with wavelength of the ZnO thin films obtained in comparative example 1 and comparative example 2;

FIG. 3 is an atomic force microscope topography of the ZnO film obtained in comparative example 1;

FIG. 4 is a graph showing transmittance spectra at wavelengths of 400 to 1200nm of the conductive ZnO thin films prepared in examples 3 to 7 and the ZnO thin film of example 3, which is a four-layer stack and is not irradiated with ultraviolet light;

FIG. 5 is a graph showing the resistivity of the conductive ZnO films prepared in examples 8 to 15;

fig. 6 is a graph showing the change in resistivity delay time of the conductive ZnO thin film prepared in example 12.

Detailed Description

The invention provides a preparation method of a conductive ZnO film, which comprises the following steps:

mixing zinc acetate, ethanolamine and dimethoxyl ethanol to obtain zinc acetate precursor sol;

forming a film on the zinc acetate precursor sol on a transparent substrate to obtain a zinc acetate gel film;

carrying out heat treatment on the zinc acetate gel film to obtain a first ZnO film;

sequentially repeating the film forming and heat treatment processes for 1-5 times to obtain a multilayer stacked ZnO film;

and carrying out ultraviolet irradiation on the multilayer stacked ZnO film to obtain the conductive ZnO film.

In the present invention, all the starting materials for the preparation are commercially available products known to those skilled in the art unless otherwise specified.

The invention mixes zinc acetate, ethanolamine and dimethoxy ethanol to obtain zinc acetate precursor sol. In the invention, the zinc acetate is preferably zinc acetate dihydrate, and the zinc acetate is a zinc source for preparing ZnO; the ethanolamine is a stabilizer and simultaneously serves as alkali and a complexing agent, so that the zinc acetate precursor sol is stable, clear and transparent at normal temperature; the dimethoxy ethanol is used as a solvent.

In the invention, the dosage ratio of the zinc acetate, the ethanolamine and the dimethoxyethanol is preferably (1-2) g: (200-300) μ L: (10-25) mL, more preferably (1.2-1.8) g (220-280) μ L: (13-21) mL, most preferably (1.3-1.5) g (240-255) μ L: (16-19) mL.

In the invention, the mixing is preferably carried out under stirring, and the relative humidity of the mixing is preferably 15-30%, more preferably 18-26%, and most preferably 20-23%; the temperature is preferably 15-40 ℃, more preferably 20-35 ℃, and most preferably 25-30 ℃; the time is preferably 8 to 12 hours, and more preferably 9 to 11 hours. The stirring rate is not particularly limited in the present invention, and may be carried out at a rate known to those skilled in the art.

After the mixing is completed, the invention also preferably adopts a 0.045 μm filter for filtration so as to obtain clear and transparent zinc acetate precursor sol.

After obtaining the zinc acetate precursor sol, the invention forms a film on the transparent substrate by using the zinc acetate precursor sol to obtain the zinc acetate gel film.

In the present invention, the material of the transparent substrate is not limited in any way, and a transparent substrate known to those skilled in the art may be used. In the present invention, it is preferable that the method further comprises cleaning the transparent substrate before forming a film on the transparent substrate;

the cleaning is preferably carried out by placing the transparent substrate in an ultra-clean space and blowing air flow with the relative humidity of 15-30%; the relative humidity of the air flow is preferably 18-25%.

In the invention, the air flow is preferably 500-3000 m³More preferably 600 to 2800m³A/h, most preferably 700 to 2000m³/h。

In the invention, the relative humidity of the formed film is preferably 15-30%, and more preferably 18-25%; the temperature is preferably 15 to 40 ℃, and more preferably 20 to 30 ℃.

In the invention, the film forming mode is preferably spin coating or blade coating; the spin coating or doctor-blading process is not particularly limited in the present invention, and may be performed by a process well known to those skilled in the art.

In the invention, the temperature of the heat treatment is preferably 240-360 ℃, more preferably 280-350 ℃, and most preferably 300-310 ℃; the time is preferably 30 to 60min, and more preferably 35 to 40 min. In the present invention, the relative humidity of the heat treatment is preferably 15 to 30%, and more preferably 18 to 25%.

In the present invention, the heat treatment is preferably performed in a heating stage.

After the first layer of ZnO film is obtained, the film forming and heat treatment processes are sequentially repeated for 1-5 times, and the multilayer stacked ZnO film is obtained. In the present invention, the number of repetitions is preferably 2 to 4.

After the multilayer stacked ZnO thin film is obtained, the invention carries out ultraviolet irradiation on the multilayer stacked ZnO thin film to obtain the conductive ZnO thin film.

In the present invention, the ultraviolet light irradiation is preferably performed in an anhydrous and oxygen-free environment; the effective power of the ultraviolet irradiation is preferably 60W, the wavelength is preferably 250-396 nm, and more preferably 300-360 nm; the time is preferably 5 to 60min, and more preferably 20 to 50 min.

In the invention, the ultraviolet light irradiation can induce atoms such as carbon, hydrogen and the like which are generated after decomposition of carbonyl-containing organic matters such as acetate and the like remained in the multilayer stacked ZnO film to diffuse to a grain boundary, and the atoms act as a shallow donor level in the ZnO film and are heavily doped, so that trapped electrons are easy to jump to a conduction band, the electron concentration of the conduction band is increased, and the resistivity of the ZnO film is reduced.

The invention also provides the conductive ZnO film prepared by the preparation method of the technical scheme, which is characterized in that the number of the conductive ZnO films is 1-6.

In the invention, the total thickness of the conductive ZnO film is preferably 20-150 nm, and more preferably 40-136 nm;

the thickness of each layer is preferably 15-35 nm independently, and more preferably 18-33 nm;

the total thickness of the conductive ZnO film is preferably greater than the thickness of each layer.

The conductive ZnO thin film and the method for preparing the same according to the present invention will be described in detail with reference to the following examples, which should not be construed as limiting the scope of the present invention.

Example 1

Mixing and stirring 1.0g of zinc acetate dihydrate, 277 mu L of ethanolamine and 10mL of dimethoxy ethanol for 12h under the conditions that the relative humidity is 30% and the temperature is 20 ℃ to obtain zinc acetate precursor sol;

placing transparent glass with thickness of 1.0mm in ultra-clean space at 1500m³Blowing air flow with the relative humidity of 23% into the transparent glass, and cleaning the transparent glass to obtain cleaned transparent glass;

in the environment with the temperature of 30 ℃ and the relative humidity of 23%, spin-coating 100 mu L of the zinc acetate precursor sol on transparent glass to form a film, so as to obtain a zinc acetate gel film;

placing the zinc acetate gel film on a heating table for heat treatment in an environment with the relative humidity of 23%, wherein the temperature of the heat treatment is 320 ℃, and the time is 30min, so as to obtain a first ZnO film (23.19 nm);

repeating the above film formation and heat treatment process 1 time to obtain two-layer stacked ZnO thin film (total thickness of 42.05 nm);

carrying out ultraviolet irradiation on the two-layer stacked ZnO thin film in an anhydrous oxygen-free environment, wherein the effective power of the ultraviolet irradiation is 60W, the wavelength is 365nm, and the time is 5min, so as to obtain the conductive ZnO thin film, wherein the resistivity is 1.07 multiplied by 10^-2Ω·cm。

Example 2

Mixing and stirring 1.0g of zinc acetate dihydrate, 277 mu L of ethanolamine and 10mL of dimethoxy ethanol for 12h under the conditions that the relative humidity is 30% and the temperature is 20 ℃ to obtain zinc acetate precursor sol;

placing transparent glass with thickness of 1.0mm in ultra-clean space at 1500m³Blowing air flow with the relative humidity of 23% into the transparent glass, and cleaning the transparent glass to obtain cleaned transparent glass;

in the environment with the temperature of 30 ℃ and the relative humidity of 23%, spin-coating 100 mu L of the zinc acetate precursor sol on transparent glass to form a film, so as to obtain a zinc acetate gel film;

placing the zinc acetate gel film on a heating table for heat treatment in an environment with the relative humidity of 23%, wherein the temperature of the heat treatment is 320 ℃, and the time is 30min, so as to obtain a first ZnO film (23.19 nm);

repeating the above film formation and heat treatment process 2 times to obtain a three-layer stacked ZnO thin film (total thickness of 74.44nm, thicknesses of the second layer and the third layer of 18.14nm and 32.39nm, respectively);

carrying out ultraviolet irradiation on the two stacked ZnO films in an anhydrous and oxygen-free environment, wherein the effective power of the ultraviolet irradiation is 60W, the wavelength is 365nm, and the time is 10min to obtain the conductive ZnO film, and the resistivity of the conductive ZnO filmIs 7.82X 10^-3Ω·cm。

Example 3

Mixing and stirring 1.0g of zinc acetate dihydrate, 277 mu L of ethanolamine and 10mL of dimethoxy ethanol for 12h under the conditions that the relative humidity is 30% and the temperature is 20 ℃ to obtain zinc acetate precursor sol;

placing transparent glass with thickness of 1.0mm in ultra-clean space at 1500m³Blowing air flow with the relative humidity of 23% into the transparent glass, and cleaning the transparent glass to obtain cleaned transparent glass;

in the environment with the temperature of 30 ℃ and the relative humidity of 23%, spin-coating 100 mu L of the zinc acetate precursor sol on transparent glass to form a film, so as to obtain a zinc acetate gel film;

placing the zinc acetate gel film on a heating table for heat treatment in an environment with the relative humidity of 23%, wherein the temperature of the heat treatment is 320 ℃, and the time is 30min, so as to obtain a first ZnO film (23.19 nm);

repeating the above film formation and heat treatment 3 times to obtain a four-layer stacked ZnO film (total thickness of 94.97, thicknesses of the second, third and fourth layers of 18.14nm, 32.39nm and 20.35nm, respectively);

carrying out ultraviolet irradiation on the four-layer stacked ZnO film in an anhydrous oxygen-free environment, wherein the effective power of the ultraviolet irradiation is 60W, the wavelength is 365nm, and the time is 5min, so as to obtain the conductive ZnO film, wherein the resistivity is 1.06 multiplied by 10^-2Ω·cm。

Example 4

Referring to the preparation process of example 3 except that the ultraviolet irradiation time was 10min, the conductive ZnO thin film was obtained with a resistivity of 7.41 × 10^-3Ω·cm。

Example 5

Referring to the preparation process of example 3 except that the ultraviolet irradiation time was 20min, the conductive ZnO thin film was obtained with a resistivity of 6.27 × 10^-3Ω·cm。

Example 6

Reference example 3 preparation procedure, differing only by UV irradiationIrradiating for 30min to obtain the conductive ZnO film with resistivity of 6.30 × 10^-3Ω·cm。

Example 7

Referring to the preparation process of example 3 except that the ultraviolet irradiation time was 60min, the conductive ZnO thin film was obtained with a resistivity of 6.25 × 10^-3Ω·cm。

Example 8

Mixing and stirring 1.0g of zinc acetate dihydrate, 277 mu L of ethanolamine and 10000 mu L of dimethoxy ethanol for 12 hours under the conditions of relative humidity of 30% and temperature of 20 ℃ to obtain zinc acetate precursor sol;

placing transparent glass with thickness of 1.0mm in ultra-clean space at 1500m³Blowing air flow with the relative humidity of 23% into the transparent glass, and cleaning the transparent glass to obtain cleaned transparent glass;

in the environment with the temperature of 30 ℃ and the relative humidity of 23%, spin-coating 100 mu L of the zinc acetate precursor sol on transparent glass to form a film, so as to obtain a zinc acetate gel film;

placing the zinc acetate gel film on a heating table for heat treatment in an environment with the relative humidity of 23%, wherein the temperature of the heat treatment is 320 ℃, and the time is 30min, so as to obtain a first ZnO film (23.19 nm);

repeating the above film formation and heat treatment processes 5 times to obtain six-layered stacked ZnO films (total thickness of 135.27, thicknesses of the second, third, fourth, fifth, and sixth layers of 18.41nm, 32.39nm, 20.35nm, 19.51nm, and 20.79nm, respectively);

carrying out ultraviolet irradiation on the six-layer stacked ZnO film in an anhydrous oxygen-free environment, wherein the effective power of the ultraviolet irradiation is 60W, the wavelength is 365nm, and the time is 5min, so as to obtain the conductive ZnO film, wherein the resistivity is 5.52 multiplied by 10^-3Ω·cm。

Example 9

Referring to the preparation process of example 8 except that the ultraviolet irradiation time was 10min, the conductive ZnO thin film was obtained, which had a resistivity of 3.92 × 10^-3Ω·cm。

Example 10

Referring to the preparation process of example 8 except that the ultraviolet irradiation time was 15min, the conductive ZnO thin film was obtained, which had a resistivity of 3.14 × 10^-3Ω·cm。

Example 11

Referring to the preparation process of example 8 except that the ultraviolet irradiation time was 20min, the conductive ZnO thin film was obtained with a resistivity of 2.80 × 10^-3Ω·cm。

Example 12

Referring to the preparation process of example 8 except that the ultraviolet irradiation time was 25min, the conductive ZnO thin film was obtained, which had a resistivity of 2.26 × 10^-3Ω·cm。

Example 13

Referring to the preparation process of example 8 except that the ultraviolet irradiation time was 30min, the conductive ZnO thin film was obtained, which had a resistivity of 2.22 × 10^-3Ω·cm。

Example 14

Referring to the preparation process of example 8 except that the ultraviolet irradiation time was 35min, the conductive ZnO thin film was obtained with a resistivity of 2.22 × 10^-3Ω·cm。

Example 15

Referring to the preparation process of example 8 except that the ultraviolet irradiation time was 40min, the conductive ZnO thin film was obtained with a resistivity of 2.23 × 10^-3Ω·cm。

Comparative example 1

Mixing and stirring 1.0g of zinc acetate dihydrate, 277 mu L of ethanolamine and 10000 mu L of dimethoxy ethanol for 12 hours under the conditions that the relative humidity is 30% and the temperature is 20 ℃ to obtain zinc acetate precursor sol;

placing transparent glass with thickness of 1.0mm in ultra-clean space at 1500m³Blowing air flow with the relative humidity of 23% into the transparent glass, and cleaning the transparent glass to obtain cleaned transparent glass;

in the environment with the temperature of 30 ℃ and the relative humidity of 23%, spin-coating 100 mu L of the zinc acetate precursor sol on transparent glass to form a film, so as to obtain a zinc acetate gel film;

placing the zinc acetate gel film on a heating table for heat treatment in an environment with the relative humidity of 23%, wherein the temperature of the heat treatment is 320 ℃, and the time is 30min, so as to obtain a layer of ZnO thin film (23.91 nm);

carrying out ultraviolet irradiation on the ZnO film in an anhydrous oxygen-free environment, wherein the effective power of the ultraviolet irradiation is 60W, the wavelength is 368nm, and the time is 5min, so as to obtain the conductive ZnO film, wherein the resistivity is 2.40 multiplied by 10^-2Ω·cm。

Comparative example 2

Mixing and stirring 1.0g of zinc acetate dihydrate, 277 mu L of ethanolamine and 10000 mu L of dimethoxy ethanol for 12 hours under the conditions that the relative humidity is 30% and the temperature is 20 ℃ to obtain zinc acetate precursor sol;

placing transparent glass with thickness of 1.0mm in ultra-clean space at 1500m³Blowing air flow with the relative humidity of 23% into the transparent glass, and cleaning the transparent glass to obtain cleaned transparent glass;

in the environment with the temperature of 30 ℃ and the relative humidity of 23%, spin-coating 100 mu L of the zinc acetate precursor sol on transparent glass to form a film, so as to obtain a zinc acetate gel film;

placing the zinc acetate gel film on a heating table for heat treatment at 320 deg.C for 30min in an environment with a relative humidity of 23%, to obtain a ZnO film (23.90nm) with a resistivity of 3.73 × 10²Ω·cm。

Test example

FIG. 1 shows the absorption coefficients of ZnO thin films obtained in comparative example 1 and comparative example 2 under different energies, and as can be seen from the resistivity of FIG. 1 and comparative examples 1-2, in the ultraviolet visible light region, the ultraviolet light irradiation only changes the conductivity without changing the absorption coefficients;

FIG. 2 is a graph showing the change of the film refractive index and extinction coefficient with wavelength of the ZnO thin films obtained in comparative example 1 and comparative example 2; wherein the content of the first and second substances,andthe refractive indices of the ZnO films obtained in comparative example 2 and comparative example 1, respectively;andthe extinction coefficients of the ZnO films obtained in comparative example 2 and comparative example 1 are represented respectively; as can be seen from FIG. 2, within 400-1700 nm, the extinction coefficients of the comparative example 1 and the comparative example 2 are both 0, and the wave-absorbing section has no absorption, i.e. the ultraviolet irradiation treatment has no influence on the extinction coefficient of the film; the refractive index of each wave band is slightly reduced after the ultraviolet irradiation treatment;

FIG. 3 is an atomic force microscope topography of the ZnO film obtained in comparative example 1, and it can be seen from FIG. 3 that the surface roughness of the ZnO film obtained in comparative example 1 is 0.86nm, which illustrates that the surface of the ZnO film prepared by the sol-gel method is flat and smooth;

fig. 4 is a transmittance spectrum of the conductive ZnO films prepared in examples 3 to 7 and the ZnO film of example 3, which is not subjected to ultraviolet irradiation, stacked in four layers at wavelengths of 400 to 1200nm, and it can be seen from fig. 3 that the transmittance of the conductive ZnO films prepared in examples 3 to 7 and the ZnO film of example 3, which is not subjected to ultraviolet irradiation, stacked in four layers is 85% or more at wavelengths of 400 to 1200nm, indicating that the transmittance of the film without ultraviolet irradiation treatment is also 85% or more, i.e., the transmittance is not changed by the ultraviolet irradiation treatment.

FIG. 5 shows the resistivity of the conductive ZnO thin films prepared in examples 8 to 15, and it can be seen from FIG. 5 that when the UV irradiation time reaches 25min, the resistivity is at a minimum and the conductivity reaches a maximum saturation value.

Fig. 6 is a variation curve of the resistivity delay time of the conductive ZnO thin film prepared in example 12, and it can be seen from fig. 6 that the resistivity is increased with the increase of the storage time, but the variation trend is small, and after 450min, the conductivity can be maintained at the same order of magnitude, which indicates that the conductivity stability is better.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.