High-transmittance flexible conductive ITO film and preparation method thereof

Abstract

This invention relates to the field of ITO thin film materials, specifically to a high-transmittance flexible conductive ITO thin film and its preparation method, comprising a first ITO thin film layer, a graphene microgrid layer, and a second ITO thin film layer. The first and second ITO thin film layers have the same thickness, both ranging from 50 to 250 nm. The ITO thin film prepared by this invention has extremely high visible light transmittance and extremely low resistance, as well as good conductivity, and can be widely used in electronic devices.

Description

Technical Field

[0001] This invention relates to the field of ITO thin film materials, specifically to a high-transmittance flexible conductive ITO thin film and its preparation method. Background Technology

[0002] Indium tin oxide (ITO) films, as transparent conductive oxide films, possess high visible light transmittance and good conductivity, thus being widely used in numerous fields such as flat panel displays, sensors, and solar cells. Currently, with the increasing demand for ultra-high-definition, ultra-large-size, and large-size touch display panels, higher requirements are being placed on ITO conductive films. How to adjust the properties of ITO films to achieve good visible light transmittance and conductivity has become a current research hotspot. Summary of the Invention

[0003] Purpose of the invention: To address the above-mentioned technical problems, this invention proposes a high-transmittance flexible conductive ITO thin film and its preparation method.

[0004] The technical solution adopted is as follows: A high-transmittance flexible conductive ITO film comprises, in sequence, a first ITO film layer, a graphene microgrid layer, and a second ITO film layer.

[0005] Furthermore, the first ITO thin film layer and the second ITO thin film layer have the same thickness, both ranging from 50 to 250 nm, and the thickness of the graphene microgrid layer is... .

[0006] Furthermore, the first ITO thin film layer and the second ITO thin film layer have the same composition, both being metal-doped ITO thin films.

[0007] Furthermore, the metal is a transition metal element and / or a rare earth element.

[0008] Furthermore, the transition metal element is Sc and / or Y; The rare earth element is Dy and / or Yb.

[0009] This invention also provides a method for preparing a high-transmittance flexible conductive ITO thin film: A first ITO thin film layer was prepared by magnetron co-sputtering. Then, a microsphere template was attached to the surface of the first ITO thin film layer. Graphene was grown on the surface of the microsphere template by magnetron sputtering using high-purity graphite as the target material. Another microsphere template was attached to the surface of the obtained graphene layer. A second ITO thin film layer was prepared by multi-target magnetron co-sputtering. Finally, the microsphere template was washed away with solvent, and the film was dried and heat-treated.

[0010] Furthermore, the microsphere template is a polystyrene nanosphere.

[0011] Furthermore, the microsphere template was attached using the dip-coating method.

[0012] Furthermore, the heat treatment temperature is 450-650℃, and the time is 1-3 hours.

[0013] Furthermore, the heat treatment is carried out under the protection of an inert gas.

[0014] The beneficial effects of this invention are: This invention provides a high-transmittance flexible conductive ITO thin film. Doping with transition metal elements and / or rare earth elements can increase the carrier concentration in the ITO thin film layer, reduce the length of the internal conductive channels, and improve electron mobility, which is beneficial for reducing resistance and improving its electrical performance. A graphene microgrid layer is located between two ITO thin film layers. Without the addition of the graphene microgrid layer, the sheet resistance of the ITO thin film is relatively high. With the addition of the graphene microgrid layer, the sheet resistance of the ITO thin film decreases significantly, possibly because the graphene microgrid layer has a high carrier concentration. The addition of the graphene microgrid layer improves the sheet resistance of the ITO thin film. The graphene microgrid layer provides a large number of charge carriers, and when some of the graphene microgrid layers come into contact with the ITO thin film layer, it causes band bending, allowing electrons from the graphene microgrid layer to be injected into the ITO thin film layer, thereby enhancing the conductivity of the ITO thin film layer. Therefore, with the addition of the graphene microgrid layer, the sheet resistance of the ITO thin film decreases significantly. Moreover, since the graphene microgrid layer has excellent light transmittance in the visible light range, its impact on the overall transmittance of the ITO thin film is negligible. The ITO thin film prepared by this invention has extremely high visible light transmittance and extremely low resistance, as well as good conductivity, and can be widely used in electronic devices. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the ITO thin film prepared in Example 1 of the present invention; The labels in the diagram represent: 1-First ITO thin film layer, 2-Graphene microgrid layer, 3-Second ITO thin film layer; Figure 2 This is a microscopic morphology diagram of the graphene microgrid layer prepared in Example 1 of the present invention. Detailed Implementation

[0016] Unless otherwise specified in the examples, the conditions were performed under standard conditions or as recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. Techniques not mentioned in this invention refer to existing technologies. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters. Example 1:

[0017] A high-transmittance flexible conductive ITO film has a "sandwich" structure, comprising a first ITO film layer 1, a graphene microgrid layer 2, and a second ITO film layer 3. Both the first ITO film layer 1 and the second ITO film layer 3 are Y / Yb co-doped ITO films with a thickness of 240±5 nm. The graphene microgrid layer 2 has a thickness of approximately [missing information]. .

[0018] The preparation method of the above-mentioned high-transmittance flexible conductive ITO thin film: S1: The first ITO thin film layer 1 was prepared using magnetron co-sputtering. An ITO target embedded with Y and Yb sheets and a sodium-calcium glass substrate were placed in a vacuum chamber. The Y and Yb doping levels were controlled by adjusting the areas of the Y, Yb, and ITO targets in the sputtering etching region. The sodium-calcium glass substrate was first cleaned with detergent powder, then sonicated in deionized water and anhydrous ethanol for 20 min each, and finally dried with nitrogen. The sodium-calcium glass substrate was 15 cm away from the ITO target, and the sputtering background vacuum was 1 × 10⁻⁶. -4 Pa, oxygen flow rate of 0.3 ml / min, total gas pressure maintained at 0.5 Pa by controlling Ar gas, sputtering power of 100 W, sputtering time of 15 min, film thickness of approximately 240 nm, substrate temperature of 400 °C, to obtain the first ITO thin film layer 1, wherein the atomic ratio of In, Sn, Y, Yb is 9:1:0.2:0.05; S2: Styrene was placed in a separatory funnel and washed four times with 0.1 mol / L NaOH solution and water to remove the polymerization inhibitor. 1.5 g polyvinylpyrrolidone, 0.23 g sodium persulfate and 250 ml deionized water were added to a flask and stirred until a homogeneous solution was obtained. 5 g styrene was added dropwise under high-speed stirring to form an emulsion. Argon gas was introduced for protection, and the reaction was carried out in a water bath at 80 °C for 15 h. After the water bath was removed, a polystyrene emulsion was obtained. Polystyrene nanosphere templates were attached to one side of the first ITO film layer by dip-coating method. The dip-coating rate was 4 cm / min, the dip-coating time was 5 min, and the dip-coating was dried at 30 °C for 20 min. The above operation was repeated to control the thickness of the microsphere template layer. S3: The first ITO thin film layer 1 with a polystyrene nanosphere template attached to its surface is placed in a vacuum chamber. Graphene is grown on the surface of the microsphere template layer by in-situ sputtering with a graphite target for 5 minutes. The spacing between the microsphere template layer and the graphite target is 10 mm, and the sputtering background vacuum is 1 × 10⁻⁶. -4During the sputtering process, argon gas is introduced as the working gas, and the total pressure is maintained at 2 Pa by controlling the Ar gas. The sputtering power is 100 W. After sputtering, the above-mentioned impregnation and pulling operation and magnetron co-sputtering operation are repeated to form a microsphere template layer and a second ITO thin film layer 3 in sequence. Finally, the obtained semi-finished product is immersed in xylene to wash away the polystyrene nanospheres and dried at 80°C for 10 h to form a graphene micro-mesh layer 2. Then, it is placed in a tube furnace and heated to 550°C at a rate of 10°C / min for 1 h under argon protection. After that, it is naturally cooled to room temperature. Example 2:

[0019] The process is basically the same as in Example 1, except that the sample is placed in a tube furnace and heated to 650°C for 3 hours under argon protection at a rate of 10°C / min, and then allowed to cool naturally to room temperature. Example 3:

[0020] The process is basically the same as in Example 1, except that the sample is placed in a tube furnace and heated to 450°C for 2 hours under argon protection at a rate of 10°C / min, and then allowed to cool naturally to room temperature.

[0021] Comparative Example 1: It is basically the same as Example 1, except that Y doping is not performed, that is, no metal Y sheet is embedded.

[0022] Comparative Example 2: It is basically the same as Example 1, except that Yb doping is not performed, that is, no metal Yb sheet is embedded.

[0023] Comparative Example 3: It is basically the same as Example 1, except that no heat treatment is performed.

[0024] Performance testing: The high transmittance flexible conductive ITO films prepared in Examples 1-3 and Comparative Examples 1-3 were used as samples for performance testing. The sheet resistance of the sample was measured using a four-point probe system, and the average transmittance of the sample in the visible light range (350-750 nm) was measured using a U-4100 UV-Vis spectrophotometer. As shown in Table 1 above, the ITO thin film prepared by this invention has extremely high visible light transmittance and extremely low resistance, and good conductivity, and can be widely used in electronic devices.

[0025] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high transmittance flexible conductive ITO film, characterized in that, The first ITO thin film layer, the graphene micro-lattice layer and the second ITO thin film layer are sequentially arranged.

2. The high-transmittance flexible conductive ITO film according to claim 1, wherein The thickness of the first ITO thin film layer and the second ITO thin film layer is the same, and is 50-250nm, and the thickness of the graphene micro-mesh layer is 50-250nm .

3. The high-transmittance flexible conductive ITO film according to claim 1, wherein The first ITO thin film layer and the second ITO thin film layer have the same composition, and are both metal-doped ITO thin films.

4. The high-transmittance flexible conductive ITO film according to claim 3, wherein, The metal is a transition metal element and / or a rare earth element.

5. The high-transmittance flexible conductive ITO film according to claim 4, wherein, The transition metal element is Sc and / or Y. The rare earth element is Dy and / or Yb.

6. A method of producing a high-transmittance flexible conductive ITO film according to any one of claims 1 to 5, characterized by, The first ITO thin film layer is prepared by a magnetron co-sputtering method, then a microsphere template is attached to the surface of the first ITO thin film layer, high-purity graphite is used as a target material, and a graphene layer is grown on the surface of the microsphere template by a magnetron sputtering method, then a microsphere template is attached to the surface of the graphene layer, a second ITO thin film layer is prepared by a multi-target magnetron co-sputtering method, and finally the microsphere template is washed away by a solvent, and then dried and heat-treated.

7. The method of claim 6, wherein the flexible conductive ITO film has a transmittance of 90% or more. The microsphere template is polystyrene nanometer microspheres.

8. The method of claim 6, wherein the flexible conductive ITO film has a transmittance of 90% or more. The microsphere template is attached by a dip-coating method.

9. The method of claim 6, wherein the flexible conductive ITO film has a transmittance of 90% or more. The heat treatment is performed at a temperature of 450-650 DEG C for 1-3 hours.

10. The method of claim 6, wherein the flexible conductive ITO film has a high light transmittance. The heat treatment is performed under the protection of an inert gas.

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