WO2022012351A1

WO2022012351A1 - Transparent conductive electrode, preparation method therefor, and electronic device

Info

Publication number: WO2022012351A1
Application number: PCT/CN2021/104086
Authority: WO
Inventors: 王硕; 辛凯; 刘云峰
Original assignee: 华为技术有限公司
Priority date: 2020-07-13
Filing date: 2021-07-01
Publication date: 2022-01-20
Also published as: CN113936844B; CN113936844A

Abstract

Provided are a transparent conductive electrode, a preparation method therefor, and an electronic device, relating to the technical field of transparent electrical conductors, and capable of reducing the sheet resistance of transparent conductive electrodes. The transparent conductive electrode comprises a transparent substrate, and a metal mesh (2) and a metal nanowire network (3) disposed inside the transparent substrate. The metal nanowire network (3) is located in a mesh hole region of the metal mesh (2). The transparent substrate (1) comprises a first surface disposed in a thickness direction. The metal mesh (2) and the metal nanowire network (3) are exposed at the first surface, and are flush with the first surface. The transparent conductive electrode further comprises a transparent conductive modification layer (4). The transparent conductive modification layer (4) covers the first surface and the metal mesh (2) and the metal nanowire network (3) exposed at the first surface.

Description

Transparent conductive electrode and preparation method thereof, electronic device

This application claims the priority of the Chinese patent application with the application number 202010670908.9 and the invention title "Transparent Conductive Electrode and its Preparation Method, Electronic Device" submitted to the State Intellectual Property Office on July 13, 2020, the entire contents of which are incorporated by reference in this application.

technical field

The present application relates to the technical field of transparent conduction, and in particular, to a transparent conductive electrode, a preparation method thereof, and an electronic device.

Background technique

Transparent conductive electrodes (also referred to as transparent electrodes) are widely used in photoelectric conversion, information display, solid-state lighting and other fields based on their own light transmittance. Transparent conductive oxides are mostly used in existing transparent electrodes. , TCO), due to the relatively high resistivity of TCO, the square resistance of the formed transparent electrode is large, especially for the flexible substrate scenario, the square resistance of the transparent electrode can generally reach tens of ohms or even hundreds of ohms , resulting in a large increase in the resistance of the large-area transparent electrode, which in turn causes the problem that the application of the transparent electrode is limited.

Taking the application of transparent electrodes in solar cells (also known as photovoltaic cells) as an example, transparent electrodes are an important part of solar cells. Due to the high square resistance of transparent electrodes, the photoelectric conversion efficiency of solar cells is seriously affected. Solar cells are usually set up in series with multiple narrow strip sub-cells, resulting in visible lines in the solar cell itself, which greatly limits its application scenarios; for example, for the current smart wearable fields, consumer electronics, etc. Electronic products have high requirements on visibility and aesthetics, and the current solar cells that use multiple narrow strip sub-cells in series cannot meet their needs; therefore, it is necessary to design a transparent electrode with low square resistance to expand Application scenarios of solar cells.

SUMMARY OF THE INVENTION

The present application provides a transparent conductive electrode, a preparation method thereof, and an electronic device, which can reduce the square resistance of the transparent conductive electrode.

The application provides a transparent conductive electrode, including a transparent substrate, a metal grid and a metal nanowire network embedded in the transparent substrate; the metal nanowire network is located in the mesh area of the metal grid; The metal grid and the metal nanowire network are exposed on the first surface and are flush with the first surface; the transparent conductive electrode further includes: a transparent conductive modification layer; the transparent conductive modification layer covers the first surface and is exposed on the first surface. A metal mesh, metal nanowire network on a surface.

In the transparent conductive electrode provided by this application, the transparent conductive modification layer is arranged on the surface of the transparent substrate embedded with the metal grid and the metal nanowire network. On the one hand, the metal grid and the metal nanowire network are exposed on the transparent The surface of the substrate is in direct contact with the transparent conductive modification layer, so that the metal nanowire network can provide the transparent conductive modification layer with an auxiliary high-conductivity path for the lateral migration of carriers, and the metal grid can efficiently collect the carriers (with the transparent conductive electrode). For example, the application in photovoltaic cells), thereby effectively reducing the square resistance of the transparent conductive electrode; It is flush, which avoids the defects of the transparent conductive decoration layer being stepped or pierced due to the unevenness below, which may lead to failure or generate a large leakage current.

In some possible implementations, the transparent substrate further includes a second surface on the opposite side of the first surface; neither the metal grid nor the metal nanowire network is exposed on the second surface; to avoid the process of using the transparent conductive electrode, the transparent The conductive electrodes cause unnecessary electrical connections (eg, short circuits, etc.) with other lines or devices on the side of the second surface.

In some possible implementations, the metal nanowire network is embedded in the transparent substrate and the surface is covered with oxide nanoparticles; so that the metal nanowires are more compact at the overlapping position, that is, the metal nanowires at the overlapping position are reduced. The contact resistance also improves the electrical conductivity of the metal nanowire network, thereby reducing the square resistance of the transparent conductive electrode and improving the electrical conductivity of the transparent conductive electrode.

In some possible implementations, the metal nanowire network is a silver nanowire network.

In some possible implementations, the transparent conductive modification layer includes one or more of transparent conductive oxides, transparent conductive polymers, carbon nanotubes, and graphene.

In some possible implementations, the transparent substrate is a flexible substrate.

The embodiments of the present application also provide electronic devices, including the transparent conductive electrodes provided in any of the foregoing possible implementation manners.

In some possible implementations, the electronic device includes a photovoltaic cell; at least one electrode in the photovoltaic cell adopts a transparent conductive electrode.

The embodiment of the present application also provides a method for preparing a transparent conductive electrode, which includes: forming a colloidal layer on a substrate; forming a hollow grid groove on the colloidal layer to obtain a colloidal pattern layer; forming a metal mesh on the substrate in the mesh groove of the quality pattern layer, and removing the colloidal pattern layer; forming a metal nanowire network on the substrate located in the mesh area of the metal mesh; forming a metal mesh and metal mesh on the substrate; A polymer transparent film layer is formed on the substrate of the nanowire network to embed the metal grid and the metal nanowire network in the polymer transparent film layer; the polymer transparent film layer and the metal mesh embedded in the polymer transparent film layer are The whole grid and the metal nanowire network are peeled off from the substrate to obtain a transparent conductive substrate; a transparent conductive modification layer is formed on the surface of the peeled side of the transparent conductive substrate.

Using the production method of the present application, by first fabricating metal grids and metal nanowire networks on the substrate, and then forming a polymer transparent film layer (that is, a transparent substrate serving as a transparent conductive electrode), that is, using "reverse embedding" "Process" embeds the metal grid and the metal nanowire network into the transparent substrate. The wire network can provide an auxiliary high-conductivity path for the lateral migration of carriers to the transparent conductive modification layer, and the metal grid can efficiently collect the carriers (taking the application of transparent conductive electrodes in photovoltaic cells as an example), which effectively reduces the transparent square resistance of conductive electrodes; on the other hand, without the need for additional complex planarization processes (such as chemical or mechanical polishing), the metal grid, metal nanowire network, transparent substrate The side in contact with the transparent conductive modification layer is coplanar (that is, the interface with zero steps and ultra-low roughness), thereby ensuring the flatness of the transparent conductive modification layer and avoiding the appearance of steps due to unevenness below the transparent conductive modification layer. Or be punctured, resulting in failure or large leakage current and other drawbacks.

In some possible implementation manners, forming hollow grid grooves on the colloidal layer to obtain the colloidal pattern layer includes: using photolithography or nanoimprinting to form hollow grid grooves on the colloidal layer groove.

In some possible implementations, forming the metal mesh on the substrate located in the mesh grooves of the colloidal pattern layer includes: using a selective electroplating process to form metal meshes on the substrate in the mesh grooves of the colloidal pattern layer grid; wherein, the substrate is a conductive substrate.

In some possible implementation manners, forming the metal nanowire network on the substrate located in the mesh area of the metal grid includes: using a coating process to fill the solution containing nano-metal wires into the mesh area of the metal grid, to A metal nanowire network is formed on the substrate in the mesh area of the metal mesh.

In some possible implementation manners, forming the metal nanowire network on the substrate located in the mesh area of the metal mesh includes: filling the mesh of the metal mesh with a solution containing nano-metal wires and oxide nanoparticles using a coating process A hole region is formed to form a metal nanowire network whose surface is covered with oxide nanoparticles on the substrate in the mesh region of the metal grid.

The solution containing oxide nanoparticles and metal nanowires can provide capillary force in the process of solvent evaporation. The oxide nanoparticles randomly aggregate on the surface of metal nanowires, especially on the surface of the overlapping position of metal nanowires. The metal nanowires are made closer at the overlapping position, the contact resistance of the metal nanowires at the overlapping position is reduced, and the electrical conductivity of the metal nanowire network is improved.

In some possible implementation manners, forming the metal nanowire network on the substrate located in the mesh area of the metal mesh includes: firstly using a coating process to fill the mesh area of the metal mesh with a solution containing nano metal wires to form a metal mesh The nanowire network, and then the solution containing oxide nanoparticles is filled into the mesh area of the metal mesh by a coating process to form a metal surface covered with oxide nanoparticles on the substrate in the mesh area of the metal mesh. Nanowire network.

In the process of solvent evaporation, it can provide capillary force, and the oxide nanoparticles are randomly aggregated on the surface of the metal nanowire network, especially on the surface of the overlapping position of the metal nanowires, which can make the metal nanowires more closely at the overlapping position. The contact resistance of the metal nanowires at the overlapping position is reduced, that is, the electrical conductivity of the metal nanowire network is improved.

Description of drawings

1 is an exploded schematic structural diagram of a transparent conductive electrode provided by an embodiment of the present application;

2 is a schematic cross-sectional structure diagram of the transparent conductive electrode of FIG. 1;

3 is a schematic structural diagram of a partial film layer of a transparent conductive electrode provided by an embodiment of the present application;

4 is a flow chart of a method for preparing a transparent conductive electrode provided by an embodiment of the present application;

5 is a schematic structural diagram of a preparation process of a transparent conductive electrode provided by an embodiment of the present application;

FIG. 6 is a schematic structural diagram of a photovoltaic cell according to an embodiment of the present application.

detailed description

In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly described below with reference to the accompanying drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, and Not all examples. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

The terms "first", "second", etc. in the description, embodiments and claims of the present application and the drawings are only used for the purpose of distinguishing and describing, and should not be construed as indicating or implying relative importance, nor should they be construed as indicating or implied order. Furthermore, the terms "comprising" and "having" and any variations thereof, are intended to cover non-exclusive inclusion, eg, comprising a series of steps or elements. A method, system, product or device is not necessarily limited to those steps or units expressly listed, but may include other steps or units not expressly listed or inherent to the process, method, product or device. "Upper", "lower", etc. are only used relative to the orientation of components in the drawings, these directional terms are relative concepts, and they are used for relative description and clarification, which may be The orientation in which the component is placed changes accordingly.

An embodiment of the present application provides a transparent conductive electrode, as shown in FIG. 1 (an exploded schematic view) and FIG. 2 (a schematic cross-sectional view of FIG. 1 ), the transparent conductive electrode includes a transparent substrate 1 (with non-conductivity) and is embedded in a transparent The metal mesh 2 and the metal nanowire network 3 in the substrate 1 ; wherein, the metal nanowire network 3 is located in the mesh area C of the metal mesh 2 .

Referring to FIG. 3 (some film layers are omitted), the transparent substrate 1 includes a first surface A1 (also referred to as an upper surface) on the first side in the thickness direction DD' and a second surface A2 ( It can also be referred to as the lower surface); wherein, on the first side where the transparent conductive electrode is located in the thickness direction DD', the metal mesh 2 and the metal nanowire network 3 expose the first surface A1 and are flush with the first surface A1; That is, the metal mesh 2, the metal nanowire network 3 and the transparent substrate 1 are coplanar on the first side.

In addition, as shown in FIG. 2 , the transparent conductive electrode further includes: a first surface A1 covering the transparent substrate 1 and a transparent conductive modification layer 4 exposed on the first surface A1 of the metal mesh 2 and the metal nanowire network 3 . That is to say, the transparent conductive modification layer 4 will be in direct contact with the metal mesh 2 and the metal nanowire network 3 exposed on the transparent substrate 1; in this way, taking the use of transparent conductive electrodes in photovoltaic cells as an example, the metal nanowire The network can provide an auxiliary high-conductivity path for the lateral migration of carriers in the transparent conductive modification layer, and the metal grid can efficiently collect the carriers, that is to say, the metal grid and the metal nanowire network promote the lateral transfer of carriers. migration and efficient collection; thus, the square resistance of the transparent conductive electrode can be greatly reduced.

In addition, it can also be understood that, in the transparent conductive electrode provided by the present application, the metal mesh 2 , the metal nanowire network 3 and the transparent substrate 1 are coplanar on the first side, so as to ensure that they are located on the upper side of the transparent substrate 1 The transparent conductive decoration layer has good flatness, thereby avoiding the defects of the transparent conductive decoration layer being stepped or being pierced due to the unevenness below, resulting in failure or generating a large leakage current.

To sum up, in the transparent conductive electrode provided by this application, the transparent conductive modification layer is arranged on the surface of the transparent substrate embedded with the metal grid and the metal nanowire network. The wire network exposed on the surface of the transparent substrate is in direct contact with the transparent conductive modification layer, so that the metal nanowire network can provide an auxiliary high conductive path for the lateral migration of carriers to the transparent conductive modification layer, and the carriers can be transferred through the metal grid. Efficient collection (taking the application of transparent conductive electrodes in photovoltaic cells as an example), thereby effectively reducing the square resistance of transparent conductive electrodes; on the other hand, by setting metal grids, metal nanowire networks, and transparent substrates The surface of the side contacted by the decoration layer is flush, which avoids the occurrence of steps or punctures of the transparent conductive decoration layer due to the unevenness below, resulting in failure or generation of large leakage current and other drawbacks.

It can be understood here that, compared with the related art, the square resistance of the transparent conductive electrode is too large, and the thickness of the transparent conductive electrode needs to be increased to reduce its square resistance, resulting in a decrease in the transmittance of the transparent conductive electrode. The transparent conductive electrode effectively reduces the square resistance, thereby ensuring the light transmittance of the transparent conductive electrode.

On this basis, referring to FIG. 2 , in order to avoid the process of using the transparent conductive electrode, the transparent conductive electrode causes unnecessary electrical connection (such as short circuit, etc.) with other circuits or devices on the side of the second surface A2. In some possible implementation manners, neither the metal grid 2 nor the metal nanowire network 3 may be set to expose the second surface A2 of the transparent substrate 1 .

Of course, according to actual needs, if the transparent conductive electrode needs to conduct electricity on the second surface A2, the metal grid 2 can also be set to expose the second surface A2, which is not specifically limited in this application, and the following embodiments are all based on the metal grid 2 And the metal nanowire network 3 is not exposed to the second surface A2 of the transparent substrate 1 as an example to illustrate.

The specific arrangement of the transparent substrate 1 , the metal grid 2 , the metal nanowire network 3 , and the transparent conductive modification layer 4 will be further described below.

The transparent substrate 1 in the present application may be a flexible substrate, but is not limited thereto. The embodiments of the present application are all described by taking the transparent substrate 1 as the flexible substrate as an example.

The present application does not limit the material used for the transparent substrate 1 . For example, the transparent substrate 1 can be made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), cyclic olefin copolymer (COC), polyimide (PI), Blue optical adhesive (NOA 63) or one or more high molecular polymers in polyvinyl alcohol (PVA), polydimethylsiloxane (PDMS) or polymethyl methacrylate (PMMA).

The application does not specifically limit the metal material used for the metal grid 2 . For example, the metal material used for the metal grid 2 may include one or more of copper (Cu), silver (Ag), gold (Au), aluminum (Al), nickel (Ni), and zinc (Zn). There are no restrictions on the application.

In addition, the present application does not limit the shape of the mesh area of the metal mesh 2, for example, it may be a mixture of one or more of regular hexagons, rectangles, squares, diamonds, triangles or other random interconnection patterns.

In some possible implementations, the thickness of the metal grid 2 is 0.5 μm to 15 μm, that is, the thickness of the grid of the metal grid 2 is 0.5 μm to 15 μm; of course, it is not limited to this, and can be implemented according to actual needs. set up.

In some possible implementation manners, the width of the metal grid 2 is 0.5 μm to 10 μm, that is, the width of the grid forming the metal grid 2 is 0.5 μm to 10 μm; of course, it is not limited to this, and can be implemented according to actual needs. set up.

In some possible implementation manners, the ratio of the thickness to the width of the grid of the metal grid 2 is greater than 1:1, so as to ensure the electrical conductivity requirement of the metal grid 2 .

In some possible implementations, the total area of the metal grid 2 accounts for less than 20% of the total area of the transparent substrate 1; that is, the sum of the projected areas of the metal grid 2 on the transparent substrate 1 accounts for the total area of the transparent substrate 1. 20% or less of the area; of course, it is not limited to this, and can be set as required in practice.

The application does not specifically limit the metal material used in the metal nanowire network 3. For example, the metal material used in the metal nanowire network 3 may be gold or silver (ie, gold nanowire network, silver nanowire network).

Schematically, taking the metal nanowire network 3 as a silver nanowires (AgNWs) network as an example, in the process of forming the AgNWs network, a solution containing silver nanowires (AgNWs) can be obtained by evaporation and drying. For details, please refer to Method examples provided later.

In some possible implementations, the aspect ratio of the AgNWs is greater than or equal to 1000; schematically, the wire length of the AgNWs can be 1 μm-200 μm, and the wire diameter can range from 5 nm to 100 nm; the thickness of the AgNWs network can be in the range of 10 nm to 100 nm.

The present application does not limit the material used for the transparent conductive modification layer 4 . For example, the transparent conductive modification layer 4 may adopt one or more combinations of transparent conductive oxides, transparent conductive polymers, carbon nanotubes (CNTs, CNTs), and graphene.

Illustratively, the transparent conductive oxide may be indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), antimony-doped tin oxide (ATO), gallium-doped zinc oxide (GZO), One or more combinations of boron-doped zinc oxide (BZO); the transparent conductive polymer may be PEDOT:PSS.

In some possible implementations, the thickness of the transparent conductive modification layer 4 may be 10 nm to 150 nm; of course, it is not limited to this, and can be set as required in practice.

In addition, in some possible implementations, in the transparent conductive electrode, the surface of the metal nanowire network 3 embedded in the transparent substrate 1 is covered with oxide nanoparticles.

Illustratively, in some embodiments, the oxide nanoparticles covering the surface of the metal nanowire network 3 may be treated with a solution having oxide nanoparticles on the surface of the metal nanowire network 3, and the oxide nanoparticles in the solution In the process of solvent evaporation, capillary force can be provided, so as to continuously gather on the surface of the metal nanowire network 3 and its overlapping position, so that the metal nanowires can be located at the overlapping position (that is, the node of the metal nanowire network 3 ). position) is closer, that is, the contact resistance of the metal nanowires at the overlapping position is reduced, and the electrical conductivity of the metal nanowire network is improved, which in turn reduces the square resistance of the transparent conductive electrode and improves the conductivity of the transparent conductive electrode. .

Of course, for the specific fabrication method of the oxide nanoparticles covering the surface of the metal nanowire network 3, reference may be made to the fabrication method provided in the subsequent embodiments, and details are not described herein again.

The present application does not limit the specific materials of the oxide nanoparticles covering the surface of the metal nanowire network 3, which can be selected and set according to actual needs.

Illustratively, in some possible implementations, the aforementioned metal oxide nanoparticles can be titanium dioxide (TiO ₂ ), zirconium dioxide (ZrO ₂ ), silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), One or more of zinc oxide (ZnO) and tin oxide (SnO _{2 ).}

In some possible implementations, a conductive polymer coating (eg PEDOT:PSS) can be coated on the surface of the oxide nanoparticles covering the surface of the metal nanowire network 3, thereby enhancing the mechanical stability of the metal nanowire network, Provide stronger bonding force to the metal nanowire network, improve the adhesion between the metal nanowire network and the substrate, and also play an isolation and protection role for the metal nanowire.

The embodiment of the present application also provides a method for preparing a transparent conductive electrode, as shown in FIG. 4 , the preparation method includes:

Step 01 , as shown in FIG. 5( a ), a colloidal layer 11 is formed on the substrate 10 .

Of course, before the colloidal layer 11 is formed on the substrate 10 , the substrate 10 generally needs to be cleaned and dried.

The type of the substrate 10 is not limited in this application, and it can be a conductive substrate or a non-conductive substrate. In practice, it can be selected according to the manufacturing process (for details, please refer to the subsequent steps of manufacturing the metal mesh 2 ); the following embodiments of the present application All are illustrated schematically by taking the substrate 10 as an example of a conductive substrate.

Illustratively, the substrate 10 can be made of conductive glass such as ITO glass or FTO glass, but is not limited thereto.

Illustratively, the glue layer 11 may use photoresist, liquid photocurable material, thermal curing material, etc., but is not limited thereto.

In some possible implementation manners, the above step 01 may include: forming a colloidal layer 11 on the substrate 10 using ITO glass by spin-coating photoresist.

Specifically, FTO conductive glass (ie, substrate 10) is selected, ultrasonically cleaned and dried in detergent, deionized water, ethanol or isopropanol solution, and photoresist is spin-coated on the surface of the FTO conductive glass. The thickness of the photoresist after curing is at least equal to the required thickness of the metal grid (eg, 8 μm), and then heated, cured, and cooled to form the glue layer 11 .

Step 02. Referring to Fig. 5(b), a hollow grid groove S is formed on the glue layer 11 to obtain a glue pattern layer 11'.

In the present application, there is no limitation on the manner of forming the hollow grid trench S on the colloidal layer 10 , and in practice, it can be selected and set as required.

Illustratively, in some possible implementation manners, step 02 may include: using a photolithography method or a nanoimprint method to form a hollow grid groove S on the glue layer 11, so that the conductive glass (ie, the substrate 10 ) are exposed in the region located in the grid trench S.

The shape of the mesh area of the hollow mesh groove S formed on the glue layer 11 can be set according to the requirements of the mask pattern of the photolithography mask or the imprint pattern of the imprint template, which is not limited in this application. Schematically, the mesh area of the mesh groove S can be reused in one or more forms such as regular hexagon, rectangle, square, diamond, triangle or other random interconnected mesh patterns; of course, according to the actual selected manufacturing process , the cross section of the grid groove S may be trapezoidal, rectangular, rivet-shaped and other shapes, which are not specifically limited in the present application, and (b) in FIG.

Illustratively, in some possible implementation manners, step 02 may include exposing, developing, cleaning, drying, etc. to the photoresist layer (ie, the colloidal layer 11 ) to form hollow grid grooves in the photoresist layer groove S, and make the top surface of the FTO conductive glass (ie, the substrate 10 ) exposed at the bottom of the grid groove S; wherein, the mesh area of the grid groove S is square, and the square line spacing is 80 μm (that is, the mesh width), the cross section of the photoresist in the mesh area is a trapezoid, the narrow side of the trapezoid is 3 μm, the wide side is 4 μm, and the depth is 8 μm.

Step 03. Referring to FIG. 5(c), a metal mesh 2 is formed on the substrate located in the mesh groove S of the colloidal pattern layer 11', and the colloidal pattern layer 11' is removed (refer to FIG. 5). (d)). The plan view of the metal grid 2 may refer to FIG. 1 .

In the present application, the manner of forming the metal mesh 2 on the substrate 10 located in the mesh groove S of the colloidal pattern layer 11' in step 03 is not limited.

In some possible implementations, a selective electroplating process can be used to form the metal grid 2 on the substrate 10 (using a conductive substrate) in the grid groove S of the colloidal pattern layer 11'.

Illustratively, a selective copper electroplating process may be used to fill the upper surface of the mesh trench S with metal copper to form a dense copper metal mesh, which is cleaned and dried with deionized water or distilled water.

It should be understood that the groove width and width of the grid grooves S in the colloidal pattern layer 11 ′ directly determine the grid thickness and width of the metal grid 2 formed in step 03. Therefore, in actual production , should be designed according to the requirements, the thickness of the glue layer 11 should be controlled in step 01 , and the width, depth and spacing of the grid trenches S should be controlled in step 02 to meet the requirements of the metal grid 2 . For example, in order to meet the electrical conduction requirement of the metal grid 2, the ratio of the thickness to the width of the grid of the metal grid 2 may be set to be greater than 1:1.

In addition, for the removal of the colloidal pattern layer 11 ′ in step 03 , the colloidal pattern layer 11 ′ located outside the metal grid 2 can be removed by using a photolithography method or an etching method, so that the surface of the substrate 10 can be removed. Only metal mesh 2 remains. For example, acetone can be used to clean the remaining photoresist pattern (ie, the colloidal pattern layer 11 ′), so that the copper metal grid is completely exposed on the surface of the FTO conductive glass, and the processing such as cleaning and drying is performed; at this time, the substrate 10 is on the metal Part of the mesh area C of the mesh 2 is exposed (refer to (d) in FIG. 5 ).

Step 04 , as shown in (e) of FIG. 5 , a metal nanowire network 3 is formed on the substrate 10 located in the mesh area C of the metal mesh 2 . The plan view of the metal nanowire network 3 may refer to FIG. 1 .

This application does not limit the specific method of forming the metal nanowire network 3. Taking the formation of a silver nanowire network as an example, in some possible implementation methods, a coating process can be used to fill the solution containing nano metal wires (AgNWs). To the mesh area C of the metal mesh 2 , the solvent is volatilized through air drying, heating and other processes to form a silver nanowire network 3 on the substrate 10 of the mesh area C of the metal mesh 2 .

The above-mentioned coating technology used for forming the silver nanowire network can be processes such as spray printing, blade coating method, spin coating method, inkjet printing, etc., which is not limited in this application. Of course, in the process of filling the solution containing nano metal wires (AgNWs) into the mesh area C of the metal mesh 2, it may also include one or more processes of treating the solution remaining on the surface of the metal mesh 2 to remove The residual solution is filled as much as possible into the mesh area C of the metal mesh 2 .

Schematically, the mesh area of the copper metal grid can be uniformly filled with an AgNWs solution with an average aspect ratio of about 1000 (such as AgNWs with a diameter of ~30 nm and a length of 20 ~ 50 μm, and the solvent can be ethanol, isopropanol, etc. ), the AgNWs network was formed after air-drying.

Step 05. Referring to Fig. 5(f), a polymer transparent film layer 1' (ie, the aforementioned transparent substrate 1) is formed on the substrate 10 on which the metal mesh 2 and the metal nanowire network 3 are formed, so as to The metal mesh 2 and the metal nanowire network 3 are embedded in the polymer transparent film layer 1'.

In some possible implementations, a thermoplastic transparent polymer material can be used to form a completely covered metal mesh 2 and a metal nanowire network 3 by heating to a temperature above the glass transition temperature, through hot pressing and subsequent cooling treatment, etc. The transparent film layer (ie the polymer transparent film layer 1').

In some possible implementation manners, the polymer transparent film layer 1 ′ can also be formed by curing a polymer precursor liquid that can be dissolved in a solvent and cured after the solvent is volatilized, or is formed by heating the uncrosslinked polymer precursor liquid Curing and photocuring.

Illustratively, the transparent PI film (ie the polymer transparent film layer 1') covering the copper metal grid and the silver nanowire network can be obtained by coating a transparent polyimide (PI) precursor solution and heating and curing, The film thickness was controlled to be about 50 μm.

In this case, it can be understood that the lower surfaces of the polymer transparent film layer 1', the metal mesh 2, and the metal nanowire network 3 are in direct contact with the substrate 10, and the polymer transparent film layer 1', the metal mesh 2. The lower surfaces of the metal nanowire network 3 are in the same plane.

Step 06: Referring to FIG. 5(g), peel off the polymer transparent film layer 1', the metal mesh 2 and the metal nanowire network 3 embedded in the polymer transparent film layer 1' from the substrate 10 as a whole, A transparent conductive substrate M was obtained.

It can be understood that, in the transparent conductive substrate M obtained after peeling, the metal mesh 2 and the metal nanowire network 3 are embedded in the polymer transparent film layer 1 ′, and on the surface A of the peeling side of the transparent conductive substrate M, the metal mesh 2 and the metal nanowire network 3 are embedded in the polymer transparent film layer 1 ′. The mesh 2 and the metal nanowire network 3 expose the transparent polymer film layer 1 ′, and the surfaces of the transparent polymer film layer 1 ′, the metal mesh 2 , and the metal nanowire network 3 on the peeling side are coplanar.

Step 07 , as shown in (h) of FIG. 5 , a transparent conductive modification layer 4 is formed on the surface A of the peeling side of the transparent conductive substrate M. As shown in FIG.

Illustratively, ITO, FTO, AZO, ATO, GZO, BZO, conductive polymers (such as PEDOT:PSS, etc.), carbon nanotubes (CNTs), One or more of graphene and the like are used to form a transparent conductive modification layer 4 to obtain a composite transparent conductive electrode. Among them, ITO, FTO, AZO, ATO, GZO, BZO, etc. can be deposited by magnetron sputtering, electron beam evaporation, etc., and conductive polymers (such as PEDOT:PSS, etc.), carbon nanotubes (CNT), and graphene can be used. Other deposition processes are not specifically limited in this application. In practice, a suitable deposition process can be selected according to specific materials.

In some possible implementations, a 50-nm ITO film (ie, the transparent conductive modification layer 4 ) can be deposited on the peeled-off surface A of the transparent conductive substrate M by magnetron sputtering, thereby obtaining a composite transparent conductive electrode.

To sum up, using the manufacturing method of the present application, by first fabricating metal grids and metal nanowire networks on the substrate, and then forming a polymer transparent film layer (that is, a transparent substrate serving as a transparent conductive electrode), that is, The "reverse embedding process" is used to embed the metal grid and the metal nanowire network into the transparent substrate. On the one hand, the metal grid and the metal nanowire network can be exposed on the surface of the transparent substrate directly and directly with the transparent conductive modification layer. contact, so that the metal nanowire network can provide an auxiliary high-conductivity path for the lateral migration of carriers to the transparent conductive modification layer, and the metal grid can efficiently collect the carriers (taking the application of transparent conductive electrodes in photovoltaic cells as an example), and then The square resistance of the transparent conductive electrode is effectively reduced; on the other hand, the metal mesh and metal nanowire network are guaranteed without the need for additional complex planarization processes (such as chemical or mechanical polishing) to be planarized. , The transparent substrate is coplanar on the side in contact with the transparent conductive modification layer (that is, the interface with zero steps and ultra-low roughness), thereby ensuring the flatness of the transparent conductive modification layer and avoiding the transparent conductive modification layer. If it is uneven, it will appear steps or be punctured, resulting in failure or large leakage current.

In addition, in order to ensure that the metal nanowire network 3 formed in step 04 is closer at the overlapping position of the nanowires, that is, to reduce the contact resistance of the metal nanowires at the overlapping position, and improve the electrical conductivity of the metal nanowire network; Through step 04, a metal nanowire network 3 whose surface is covered with oxide nanoparticles is formed.

For example, in some possible implementations, a solution containing nano metal wires and oxide nanoparticles can be filled into the mesh area of the metal mesh 2 by a coating process, so that the substrate in the mesh area of the metal mesh 2 can be A metal nanowire network 3 whose surface is covered with oxide nanoparticles is formed on 10 .

Illustrated, may contain TiO ₂ nanoparticles and AgNWs dispersion solution or sol - gel solution to form coated with TiO2 nanoparticles AgNWs network by evaporation, drying process.

It can be understood here that since the AgNWs and TiO2 nanoparticles are dried to form a film by mixing the solution, there may be a very small amount of TiO2 nanoparticles on the surface of the AgNWs network in contact with the substrate 10; After the lift-off process in 06, the TiO2 nanoparticles located on the surface of the AgNWs network on the lift-off side were removed; of course, removal may not be performed.

For another example, in some possible implementation manners, a solution containing metal nanowires may be filled into the mesh area of the metal grid to form a metal nanowire network first by using a coating process, and then the metal nanowire network may be formed by using a coating process. The solution of oxide nanoparticles is filled into the mesh area of the metal mesh to form a metal nanowire network 3 whose surface is covered with oxide nanoparticles on the substrate 10 in the mesh area of the metal mesh 2 .

Illustrated, may be a dispersion containing AgNWs solution by evaporation, drying, etc., to form a network AgNWs; Then, further using a solution or dispersion containing TiO ₂ nanoparticles sol - gel solution, a low temperature (80 deg.] C), drying process , forming a network of AgNWs coated with TiO2 nanoparticles.

For both production methods forming surface covered with AgNWs network TiO ₂ nanoparticles, it will be appreciated that the TiO ₂ dispersion solution containing nanoparticles during the solvent evaporation in capillary forces can be provided, so that the aggregate metal The nanowires and the surface of the overlapped metal nanowires can make the metal nanowires at the overlapped position (that is, the node position of the metal nanowire network 3) more compact, reduce the contact resistance of the metal nanowires at the overlapped position, and That is, the electrical conductivity of the metal nanowire network is improved.

Of course, in some possible implementations, after the AgNWs network is formed, the AgNWs can be fused at the overlapping position by heating, thereby reducing the contact resistance of the metal nanowires at the overlapping position and improving the metal nanowires. Conductivity of the network.

The present application also provides an electronic device comprising any of the aforementioned transparent conductive electrodes.

There is no limitation on the setting form of the electronic device in this application, and the electronic device can be a photovoltaic cell (also called a solar cell), an organic light-emitting diode, a touch screen, a liquid crystal display panel, a transparent electromagnetic shield, a transparent 5G (5th generation mobile networks) , the fifth generation of mobile communication technology) antenna and other devices, it can also be other electronic products or equipment containing this part of the device.

This application does not limit the application scenarios of the electronic device. For illustration, taking the electronic device as a photovoltaic cell as an example, the photovoltaic cell can be applied in the field of smart wearable devices, as well as other fields such as consumer electronic devices, so as to realize photoelectric energy collection. In order to prolong battery life, etc.; wherein, smart wearable devices may include but are not limited to smart glasses, goggles, watches, bracelets, headsets, AR (augmented reality, augmented reality)/VR (virtual reality, virtual reality) Devices, etc., smart consumer electronic devices may include but are not limited to mobile phones, tablets, notebooks, smart speakers, portable smart routers, and the like.

The transparent conductive electrodes provided in the embodiments of the present application will be further described below in conjunction with photovoltaic cells.

As shown in FIG. 6 , in some possible implementations, the photovoltaic cell may include a bottom electrode E1, a first buffer layer B1, an active layer L, a second buffer layer B2, and a top electrode E2 that are stacked in sequence; of course, the photovoltaic cell may also Other components or film layers are included, which are not limited in this application. Among them, among the first buffer layer B1 and the second buffer layer B2, one is an electron transport layer and the other is a hole transport layer; the active layer L is a light absorbing material, such as a perovskite material or an organic material, and the active layer absorbs photons Excited to generate electron-hole pairs.

Taking the first buffer layer B1 as an electron transport layer and the second buffer layer B2 as a hole transport layer as an example, the active layer L absorbs photons and is excited to generate electron-hole pairs after receiving light irradiation, and the electrons pass through the first buffer layer B1 The holes are transferred to the bottom electrode E1, and the holes are transferred to the top electrode E2 through the second buffer layer B2, and the bottom electrode E1 and the top electrode E2 collect the charges to supply power to the external circuit.

In order to ensure that the active layer L can effectively receive the incident light, at least one of the bottom electrode E1 and the top electrode E2 may use the transparent conductive electrode provided in the embodiment of the present application.

For example, in some possible implementations, the bottom electrode E1 may use any one of the transparent conductive electrodes provided in the foregoing embodiments, and the top electrode E2 may use a silver thin film as the conductive electrode. For another example, in some possible implementations, the top electrode E2 adopts any one of the transparent conductive electrodes provided in the foregoing embodiments, and the bottom electrode E1 can use a silver thin film as the conductive electrode. For another example, in some possible implementation manners, both the bottom electrode E1 and the top electrode E2 may use any one of the transparent conductive electrodes provided in the foregoing embodiments. Of course, for the materials used for each film layer (eg, B1, L, B2) between the bottom electrode E1 and the top electrode E2 in the photovoltaic cell and the setting of related parameters, reference can be made to related technologies, which will not be repeated here.

Taking the arrangement of the photocell in the smart glasses as an example, the photocell can be attached to the inner side of the lens. In this case, the external light enters the photocell after passing through the lens; for another example, the photocell can also be attached to the outer side of the lens. In this case, the light from the outside is first incident on the photocell; for example, a double-layer lens can be provided, and the photocell is sandwiched between the double-layer lenses, and the lens can protect the photocell to a certain extent; this application does not specifically limit this. .

Through the actual testing of the application of the transparent conductive electrode of the present application in photovoltaic cells, the square resistance of the transparent conductive electrode of some embodiments of the present application can be reduced to about 0.1Ω, and its conductivity is improved by nearly a thousand times compared with the conventional ITO transparent electrode . Based on its high conductivity, the efficiency of photovoltaic cells is greatly improved, so that it can meet the large area demand of a single photovoltaic cell, which in turn can meet the aesthetic needs of wearable devices or consumer electronic devices, while greatly improving the battery life.

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited to this. should be covered within the scope of protection of this application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

A transparent conductive electrode, characterized by comprising a transparent substrate and a metal grid and a metal nanowire network embedded in the transparent substrate;

the metal nanowire network is located in the mesh area of the metal grid;

the transparent substrate includes a first surface in the thickness direction;

The metal mesh and the metal nanowire network are exposed on the first surface and are flush with the first surface;

The transparent conductive electrode further includes: a transparent conductive decoration layer; the transparent conductive decoration layer covers the first surface and the metal mesh and the metal nanowire network exposed on the first surface.
The transparent conductive electrode according to claim 1, wherein,

The transparent substrate further includes a second surface opposite the first surface;

Neither the metal mesh nor the metal nanowire network is exposed to the second surface.
The transparent conductive electrode according to claim 1 or 2, characterized in that,

The metal nanowire network is embedded in the transparent substrate and the surface is covered with oxide nanoparticles.
The transparent conductive electrode according to any one of claims 1-3, characterized in that,

The metal nanowire network is a silver nanowire network.
The transparent conductive electrode according to any one of claims 1-4, wherein,

The transparent conductive modification layer includes one or more of transparent conductive oxide, transparent conductive polymer, carbon nanotube, and graphene.
The transparent conductive electrode according to any one of claims 1-5, wherein the transparent substrate is a flexible substrate.
An electronic device, characterized by comprising the transparent conductive electrode according to any one of claims 1-6.
The electronic device according to claim 7, wherein,

the electronic device includes a photovoltaic cell;

At least one electrode in the photovoltaic cell adopts the transparent conductive electrode.
A method for preparing a transparent conductive electrode, comprising:

forming a colloidal layer on the substrate;

forming hollow grid grooves on the colloidal layer to obtain a colloidal pattern layer;

forming metal grids on the substrate located in the grid grooves of the colloidal pattern layer, and removing the colloidal pattern layer;

forming a network of metal nanowires on the substrate located in the mesh area of the metal mesh;

forming a polymer transparent film layer on the substrate formed with the metal grid and the metal nanowire network, so as to embed the metal grid and the metal nanowire network in the polymer transparent film layer;

peeling off the polymer transparent film layer, the metal grid and the metal nanowire network embedded in the polymer transparent film layer as a whole from the substrate to obtain a transparent conductive substrate;

A transparent conductive modification layer is formed on the surface of the peeling side of the transparent conductive substrate.
The method for preparing a transparent conductive electrode according to claim 9, wherein,

The forming of hollow grid grooves on the colloidal layer to obtain the colloidal pattern layer includes:

A photolithography method or a nano-imprint method is used to form hollow grid grooves on the colloidal layer.
The method for preparing a transparent conductive electrode according to claim 9 or 10, wherein,

The forming a metal grid on the substrate located in the grid groove of the colloidal pattern layer includes:

A metal grid is formed on the substrate in the grid groove of the colloidal pattern layer by a selective electroplating process; wherein, the substrate is a conductive substrate.
The method for preparing a transparent conductive electrode according to any one of claims 9-11, wherein,

The forming a metal nanowire network on the substrate located in the mesh area of the metal grid includes:

A solution containing metal nanowires is filled into the mesh area of the metal grid by a coating process, so as to form a metal nanowire network on the substrate in the mesh area of the metal grid.
The method for preparing a transparent conductive electrode according to any one of claims 9-11, wherein,

The forming a metal nanowire network on the substrate located in the mesh area of the metal grid includes:

A solution containing nano metal wires and oxide nanoparticles is filled into the mesh area of the metal grid by a coating process, so as to form a surface covered with oxide nanoparticles on the substrate in the mesh area of the metal grid metal nanowire network;

Alternatively, the solution containing nano metal wires is first filled into the mesh area of the metal mesh by a coating process to form a metal nanowire network, and then the solution containing oxide nanoparticles is filled into the metal mesh by a coating process. The mesh area of the mesh is used to form a metal nanowire network covered with oxide nanoparticles on the substrate in the mesh area of the metal mesh.