Conductive layer and preparation method thereof

Abstract

The invention relates to the field of optics, in particular to a conductive layer and a preparation method thereof, and the preparation method of the conductive layer comprises the step of placing a substrate and a conductive material in an accommodating cavity of an electron beam coating device. Under set conditions, oxygen is continuously filled into the containing cavity according to the set oxygen filling amount, and the electron beams are hit on the conductive material for set time, so that the conductive material is thermally evaporated and formed on the to-be-coated surface of the substrate. The near-infrared transmittance of the conductive layer obtained by the preparation method is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the field of optics, and in particular relates to a conductive layer and a preparation method thereof. Background Art

[0002] Transparent conductive films are widely used in display, touch screen and solar cell fields. Among them, the material of the most commercialized transparent conductive film is indium tin oxide (ITO). Traditional ITO has high transmittance in the visible light band, but its transmittance in the near-infrared band of 780nm~2500nm will drop significantly, which cannot meet the needs of infrared devices. Other commonly used materials such as FTO (Fluorine-doped Tin Oxide) and AZO (Aluminum-doped Zinc Oxide) have transmittances in the near-infrared band that are basically lower than 40%, which greatly limits their applications. Although traditional ITO has excellent electrical properties, due to its high carrier concentration, the plasma resonance wavelength is close to the visible light region, which limits its near-infrared transmittance. Although materials such as CuAlO2 and CuCrO2 have good optical properties in the visible to infrared region, their electrical properties are poor. This is because the industry currently believes that there is a contradiction between the conductivity and infrared transmittance of transparent conductive films, that is, the improvement of conductivity often leads to a decrease in transmittance. Therefore, balancing high transmittance and high conductivity becomes the key to the technology.

[0003] With the development of aviation technology, higher requirements are placed on infrared optical materials. At present, most infrared transparent conductive films have a single function and are difficult to be multifunctional. Therefore, it is hoped that infrared transparent conductive films can also have a higher emissivity in the mid- and far-infrared bands, so that they have functions such as infrared stealth, infrared detection and countermeasures, infrared sensing and infrared radiation cooling, and can have broader applications in civilian and military fields.

[0004] At present, the preparation process of most infrared transparent conductive films is complicated and the cost is high. For example, the Chinese invention patent application entitled "A multi-layer infrared transparent conductive film and its preparation method" (publication number CN108193179A) discloses a method for preparing a multi-layer infrared transparent conductive film. The infrared transparent conductive film with a five-layer structure of substrate, IHfO transparent conductive layer, metal layer, IHfO transparent conductive layer and Al2O3 protective layer prepared by magnetron sputtering and ion beam assisted evaporation has improved optical performance, but the process is complicated, inefficient and easy to pollute.

[0005] In summary, how to develop a multifunctional infrared transparent conductive film with high transmittance, high conductivity and simple and controllable preparation method is a technical problem currently faced. Solving this technical problem can not only expand its application field, but also promote the further development of optoelectronic technology in the civilian field. Summary of the invention

[0006] In view of this, the present invention aims to provide a conductive layer and a preparation method thereof, wherein the near-infrared transmittance of the conductive layer obtained by the preparation method is significantly improved.

[0007] To achieve the above object, the technical solution created by the present invention is implemented as follows: A method for preparing a conductive layer, comprising: Placing the substrate and the conductive material in a receiving chamber of the electron beam coating device; Under set conditions, oxygen is continuously charged into the containing cavity at a set oxygen charge, and an electron beam is directed onto the conductive material for a set time, so that the conductive material is thermally evaporated and formed on the surface of the substrate to be coated.

[0008] Further, under set conditions, the process includes: evacuating the containing chamber until the pressure in the containing chamber reaches a set pressure; wherein the set pressure is 1×10 -3 Pa~5×10 -3 Pa.

[0009] Furthermore, under set conditions, it includes: heating the containing cavity until the temperature in the containing cavity reaches a set temperature; wherein the set temperature is 280°C~350°C.

[0010] Furthermore, the oxygen filling amount is set to 10 sccm~30 sccm. Further, the time is set to 2 minutes to 5 minutes; and / or The conductive material is indium tin oxide.

[0011] Furthermore, under set conditions, the electron beam is directed onto the conductive material, including: under set conditions, the electron beam is directed onto the conductive material to form a light spot, and the beam current of the electron beam is increased until it reaches a set value; wherein the set value is 7mA~15mA.

[0012] Furthermore, under set conditions, an electron beam is projected onto a conductive material to form a light spot, and the beam current of the electron beam is increased until it reaches a set value. The preparation method further comprises: The size and position of the light spot are adjusted to maintain the rate of evaporating the conductive material at a set rate; wherein the set rate is 1Å / s~4Å / s.

[0013] Furthermore, before placing the substrate and the conductive material in the accommodating chamber of the electron beam coating device, the preparation method further includes: wrapping a high-temperature tape on the outer surface of the substrate except the surface to be coated on the substrate.

[0014] A conductive layer is prepared by the preparation method as described above, and the conductive layer is a polycrystalline structure.

[0015] Furthermore, the thickness of the conductive layer is 50nm-100nm.

[0016] Compared with the prior art, the invention can achieve the following beneficial effects: the preparation method of the conductive layer described in the invention is simple, and the near-infrared transmittance of the prepared conductive layer is significantly improved, while having higher conductivity and emissivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 A schematic diagram of a conductive layer and a substrate according to an embodiment of the present invention; Figure 2 A flow chart of a method for preparing a conductive layer according to an embodiment of the present invention; Figure 3 A schematic diagram showing the comparison of transmittance between the conductive layer described in the embodiment of the present invention and a conventional conductive layer prepared by a conventional preparation method on the market; Figure 4 A schematic diagram showing a comparison of the far-infrared emissivity spectrum of the conductive layer described in the embodiment of the present invention and the conventional conductive layer prepared by conventional preparation methods on the market; Figure 5 A schematic diagram comparing the SEM surface images of the conductive layer described in the embodiment of the present invention and the conventional conductive layer prepared by the conventional preparation method on the market; Figure 6 A schematic diagram comparing the AFM surface images of the conductive layer described in the embodiment of the present invention and the traditional conductive layer prepared by the traditional preparation method on the market.

[0018] Description of reference numerals: Conductive layer 10; substrate 11; surface to be coated 12. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the invention clearer, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the invention and do not constitute a limitation to the invention. Similar components in different embodiments use associated similar component numbers. In the following embodiments, many detailed descriptions are to enable the invention to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other components, materials, and methods. In some cases, some operations related to the invention are not shown or described in the specification, in order to avoid the core part of the invention being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a necessary sequence, unless otherwise specified that a certain sequence must be followed.

[0021] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0022] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" 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 ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0023] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0024] The present invention provides a method for preparing a conductive layer. Figure 1 and Figure 2 As shown, the method for preparing the conductive layer 10 includes steps S101-S102.

[0025] In step S101, a substrate 11 and a conductive material are placed in a receiving chamber of an electron beam coating device, wherein the substrate 11 is made of glass and the conductive material is indium tin oxide (ITO).

[0026] In one embodiment, before step S101, the preparation method further includes: cleaning the substrate 11. Specifically, the substrate 11 is ultrasonically cleaned with anhydrous ethanol for 20 minutes. Then, the surface of the substrate 11 is wiped with a solution of anhydrous ethanol: ether (V1:V2=1:1).

[0027] In step S102, under set conditions, oxygen is continuously added to the containing cavity at a set oxygen filling amount, and an electron beam is directed to the conductive material for a set time, so that the conductive material is thermally evaporated and deposited on the surface 12 to be coated of the substrate 11. The set time is 2 min to 5 min. In this embodiment, the set time is 4 min. The oxygen filling amount is set to 10 sccm to 30 sccm. In this embodiment, the oxygen filling amount is set to 15 sccm (i.e., 15 cubic centimeters per minute). The conductive material can be deposited on the surface 12 to be coated of the substrate 11 by the electron beam thermal evaporation process to form a conductive layer 10.

[0028] In one embodiment, under the set conditions, the process includes: evacuating the containing chamber until the pressure in the containing chamber reaches the set pressure. That is, evacuating the environment in the containing chamber to the set pressure. The set pressure is 1×10 -3 Pa~5×10 -3 In this embodiment, the pressure is set to 3×10 -3 Pa.

[0029] In one embodiment, under set conditions, it includes: heating the accommodating chamber until the temperature in the accommodating chamber reaches the set temperature. That is, the environment in the accommodating chamber is heated to the set temperature. Among them, the set temperature is 280℃~350℃. In this embodiment, the set temperature is 310℃. The accommodating chamber can be evacuated first, and then the accommodating chamber is heated after the pressure in the accommodating chamber reaches 8Pa. After the temperature in the accommodating chamber reaches the set temperature, oxygen can be continuously added to the accommodating chamber at a set oxygen filling amount. In one embodiment, under set conditions, an electron beam is hit on a conductive material, including: under set conditions, an electron beam is hit on a conductive material to form a light spot, and the beam current of the electron beam is increased until it reaches a set value. Among them, the set value is 7mA~15mA. In this embodiment, the set value is 8mA.

[0030] In one embodiment, under set conditions, an electron beam is hit on a conductive material to form a light spot, and after the beam current of the electron beam is increased until it reaches a set value, the preparation method further includes: adjusting the size and position of the light spot to maintain the rate of evaporating the conductive material at a set rate. The set rate is 1Å / s~4Å / s. In this embodiment, the set rate is 3.5Å / s. The rate of evaporating the conductive material can be adjusted by adjusting the position and size of the light spot. Setting the oxygen filling amount in this way can match the rate of evaporating the conductive material, so that the mobility and carrier concentration of the conductive layer change, thereby improving the transmittance of infrared light.

[0031] In one embodiment, before placing the substrate 11 and the conductive material in the accommodating chamber of the electron beam coating device, the preparation method further includes: coating the outer surface of the substrate 11 except the surface 12 to be coated of the substrate 11 with a high temperature tape. That is, the high temperature tape is coated on the surface of the substrate 11 not to be coated, so that during the evaporation process, coating can be prevented on the surface of the substrate 11 not to be coated.

[0032] In this embodiment, the specific preparation steps are as follows: select a glass with a thickness of 1 mm as the substrate 11, use anhydrous ethanol to ultrasonically clean the substrate 11, and continue cleaning for 20 minutes. Then wipe the surface of the substrate 11 with a solution of anhydrous ethanol: ether (V1:V2=1:1). Place the indium tin oxide and the cleaned substrate 11 in the receiving chamber of the electron beam coating machine, and evacuate the receiving chamber to 3×10 -3Pa, and the containing cavity is heated to raise the temperature of the containing cavity to 310°C, and oxygen is continuously charged into the containing cavity at a temperature of 310°C at a rate of 15 sccm. An electron beam is directed onto indium tin oxide to form a light spot, and the beam current of the electron beam is increased until it reaches 8 mA, which is continued for 4 minutes. The size and position of the light spot are adjusted to maintain the rate of evaporating indium tin oxide at 3.5Å / s, so that indium tin oxide is evaporated and deposited on the surface to be coated of the substrate 11, thereby forming a conductive layer 10 with a thickness of 80nm.

[0033] The preparation method of the conductive layer 10 created by the present invention is simple, and the near-infrared transmittance of the conductive layer 10 prepared by the preparation method of this embodiment is significantly improved, and at the same time, it has higher conductivity and emissivity.

[0034] See again Figure 1 As shown, the present invention also provides a conductive layer 10, which is prepared according to the preparation method described in the above embodiment. The conductive layer 10 is a polycrystalline structure. The thickness of the conductive layer 10 is 50nm~100nm.

[0035] See also Figure 3 As shown, Figure 3 A schematic diagram showing a comparison of transmittances of a conductive layer 10 prepared by the preparation method of this embodiment and a conventional conductive layer prepared by a conventional preparation method on the market is shown. Figure 3 The horizontal axis of the coordinate system is wavelength, and the vertical axis is transmittance. It can be seen that by forming a conductive layer 10 on a substrate 11 using the preparation method of this embodiment, a visible-near infrared broadband transparent conductive layer can be prepared. The conductive layer 10 can have an average initial transmittance of 84.2% in the visible light region of 380nm~2500nm and the near-infrared light region, and the initial transmittance contrast (transmittance contrast is the difference in transmittance) with the traditional conductive layer can be as high as 66.5%@2330 nm. The near-infrared transmittance of the conductive layer 10 is significantly improved, and the prepared conductive layer 10 can maintain good conductivity while significantly improving the near-infrared light transmittance, and the measured surface resistance is 100Ω / □.

[0036] See also Figure 4 As shown, Figure 4 A schematic diagram showing a comparison of the far-infrared emissivity spectra of the conductive layer 10 prepared by the preparation method of this embodiment and the conventional conductive layer prepared by the conventional preparation method on the market is shown. Figure 4The horizontal axis of the coordinate system is wavelength, and the vertical axis is emissivity. It can be seen that the average emissivity of the conductive layer 10 prepared by the preparation method of this embodiment can reach 0.77 in the medium-wave infrared of 4μm~8μm, and the average emissivity in the long-wave infrared of 8μm~25μm can reach 0.52. The average emissivity of the traditional conductive layer in the medium and long-wave infrared is only 0.11. The emissivity of the conductive layer 10 prepared by the preparation method created by the present invention in the medium and long-wave infrared is significantly improved.

[0037] See also Figure 5 As shown, Figure 5 A schematic diagram showing a comparison of SEM (Scanning Electron Microscope) surface images of the conductive layer 10 prepared by the preparation method of this embodiment and a conventional conductive layer prepared by a conventional preparation method on the market is shown. Figure 5 The left middle picture is a SEM surface picture of a conductive layer 10 with a thickness of 80 nm prepared by the preparation method of this embodiment. The right picture is a SEM surface picture of a conventional conductive layer with a thickness of 180 nm prepared by a conventional preparation method on the market. It can be seen from the figure that the surface of the conductive layer 10 prepared by the preparation method of this embodiment forms a particle shape with a size of about 25 nm to 50 nm, while the surface of the conventional conductive layer is very smooth.

[0038] See also Figure 6 As shown, Figure 6 A schematic diagram showing a comparison of AFM (Atomic Force Microscopy) surface images of the conductive layer 10 prepared by the preparation method of this embodiment and a conventional conductive layer prepared by a conventional preparation method on the market is shown. Figure 6 The upper middle figure is an AFM surface image of the conductive layer 10 prepared by the preparation method of this embodiment. Its surface roughness (R q ) is 8.32nm. Figure 6 The lower middle figure is an AFM surface image of a conventional conductive layer prepared by a conventional preparation method on the market. Its surface roughness (R q ) is 5.49nm. Figure 5 and Figure 6 It can be seen that the conductive layer 10 prepared by the preparation method of this embodiment has a textured surface, that is, a higher surface roughness, compared with the traditional conductive layer. The textured surface can increase the specific surface area, provide sufficient interface contact, and improve the interface adhesion. This is conducive to coating the surface of the conductive layer 10, and can improve the performance of the film or device formed after coating, such as improving the cycle stability and electron transfer rate of the film or device.

[0039] In summary, the present invention provides a conductive layer and a preparation method thereof. The conductive layer prepared by the preparation method of the present invention integrates the functions of high transmittance, high conductivity and high emissivity, has a simple structure, and the preparation process is simple and controllable.

[0040] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0041] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a conductive layer, characterized in that: include: Placing the substrate and the conductive material in a receiving chamber of the electron beam coating device; Under set conditions, oxygen is continuously charged into the containing cavity at a set oxygen charging amount, and an electron beam is directed onto the conductive material for a set time, so that the conductive material is thermally evaporated and formed on the surface of the substrate to be coated.

2. The method for preparing a conductive layer according to claim 1, characterized in that: The step of: under set conditions, comprising: evacuating the containing chamber until the pressure in the containing chamber reaches a set pressure; wherein the set pressure is 1×10 -3 Pa~5×10 -3 Pa.

3. The method for preparing a conductive layer according to claim 1, characterized in that: The step of heating the containing chamber under the set conditions includes: heating the containing chamber until the temperature inside the containing chamber reaches a set temperature; wherein the set temperature is 280°C to 350°C.

4. The method for preparing a conductive layer according to claim 1, characterized in that: The set oxygen filling amount is 10 sccm~30 sccm.

5. The method for preparing a conductive layer according to claim 1, characterized in that: The set time is 2min~5min; and / or The conductive material is indium tin oxide.

6. The method for preparing a conductive layer according to claim 1, characterized in that: The step of striking the conductive material with an electron beam under set conditions comprises: striking the conductive material with an electron beam under set conditions to form a light spot, and increasing the beam current of the electron beam until it reaches a set value; wherein the set value is 7mA-15mA.

7. The method for preparing a conductive layer according to claim 6, characterized in that: Under the set conditions, the electron beam is projected onto the conductive material to form a light spot, and the beam current of the electron beam is increased until it reaches a set value. The preparation method further comprises: The size and position of the light spot are adjusted to maintain the rate of evaporating the conductive material at a set rate; wherein the set rate is 1Å / s~4Å / s.

8. The method for preparing a conductive layer according to claim 1, characterized in that: Before placing the substrate and the conductive material in the accommodating chamber of the electron beam coating device, the preparation method further comprises: wrapping a high temperature tape on the outer surface of the substrate except the surface to be coated on the substrate.

9. A conductive layer, characterized in that: The conductive layer is prepared by the preparation method according to any one of claims 1 to 8, and the conductive layer is a polycrystalline structure.

10. The conductive layer according to claim 9, characterized in that The thickness of the conductive layer is 50nm-100nm.

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