阅读说明：本技术 一种柔性导电复合金属纳米线光栅材料及其制备方法 (Flexible conductive composite metal nanowire grating material and preparation method thereof ) 是由 彭茹雯 范仁浩 王京 王牧 于 2019-04-11 设计创作，主要内容包括：本发明公开一种柔性导电复合金属纳米线光栅材料,包括聚二甲基硅氧烷柔性衬底,位于所述柔性衬底上的金属纳米线光栅,以及介于金属纳米线光栅和所述柔性衬底之间的二氧化硅层。进一步还公开了该柔性导电复合金属纳米线光栅材料的制备方法。本发明克服了普通的太赫兹金属光栅结构通常缺乏柔性且光频透过率较低的缺点,对太赫兹、红外与可见光超宽带具有高光学透过率的同时还具有良好的导电性。(The invention discloses a flexible conductive composite metal nanowire grating material which comprises a polydimethylsiloxane flexible substrate, a metal nanowire grating positioned on the flexible substrate, and a silicon dioxide layer between the metal nanowire grating and the flexible substrate. Further discloses a preparation method of the flexible conductive composite metal nanowire grating material. The terahertz metal grating structure overcomes the defects that a common terahertz metal grating structure is usually lack of flexibility and low in optical frequency transmittance, and has high optical transmittance and good conductivity for terahertz, infrared and visible light ultra-broadband.)

1. The flexible conductive composite metal nanowire grating material is characterized by comprising a polydimethylsiloxane flexible substrate, a metal nanowire grating located on the flexible substrate, and a silicon dioxide layer located between the metal nanowire grating and the flexible substrate.

2. The flexible conductive composite metal nanowire grating material of claim 1, wherein the metal nanowire grating is a silver nanowire grating.

3. The flexible conductive composite metal nanowire grating material of claim 1, wherein the diameter of the silver nanowires in the silver nanowire grating is 100-300 nm.

4. The flexible conductive composite metal nanowire grating material of claim 1, wherein the period of the metal nanowire grating is 30-3000 microns, wherein the ratio of the groove width of the grating to the period is 5% -60%.

5. The flexible conductive composite metal nanowire grating material of claim 1, wherein the coverage of nanowires in the metal nanowire grating is between 18% and 63%.

6. The flexible conductive composite metal nanowire grating material of claim 1, wherein the thickness of the flexible substrate is 10-100 microns.

7. The flexible conductive composite metal nanowire grating material of claim 1, wherein the thickness of the silicon dioxide layer is 0.5-5 um.

8. A method for preparing a flexible conductive composite metal nanowire grating material according to any one of claims 1 to 7, comprising the steps of:

step 1, dropwise adding a metal nanowire ethanol dispersion liquid on a terahertz metal grating template, and performing spin coating and drying to form at least one layer of metal nanowire grating structure;

step 2, heating the terahertz metal grating template with the metal nanowire grating structure in a constant temperature box at 200-300 ℃ for 2-3 hours;

step 3, dropwise adding a silicon dioxide ethanol dispersion liquid on the metal nanowire grating structure, and forming a silicon dioxide layer on the metal nanowire grating structure after spin coating and drying;

step 4, mixing the materials in a mass ratio of 20: 1-5: 1, dripping the mixed liquid of polydimethylsiloxane and a curing agent on the surface of the silicon dioxide layer to obtain a polydimethylsiloxane/silicon dioxide aerogel/metal nanowire structure, and stripping the polydimethylsiloxane/silicon dioxide aerogel/metal nanowire structure from a terahertz metal grating template after the polydimethylsiloxane/silicon dioxide aerogel/metal nanowire structure is cured to obtain a metal nanowire-polydimethylsiloxane composite structure;

and 5, plating metal electrodes on the periphery of the grating of the composite structure to obtain the flexible conductive composite metal nanowire grating material.

9. The method according to claim 8, wherein in the step 3, the solute of the silica ethanol dispersion is fumed nano silica, and the content of the fumed nano silica is 2-10%.

10. The method according to claim 8, wherein in the steps 1 and 3, the drying temperature is 20-60 ℃ and the drying time is 5-30 minutes; in the step 4, the curing temperature is 60-100 ℃, and the curing time is 1-2 hours.

Technical Field

The invention belongs to the technical field of grating systems, and particularly relates to a flexible conductive composite metal nanowire grating material and a preparation method thereof.

Background

With the rising of research on micro-nano processing technology and artificial metamaterial, people can realize broadband transmission of a metal structure to electromagnetic waves, and research shows that the one-dimensional metal grating structure can realize high broadband transmission to transverse magnetic mode terahertz waves, and can ensure high broadband transmittance of the electromagnetic waves under the power-on condition because the metal material used by the one-dimensional metal grating structure can conduct electricity.

However, the one-dimensional terahertz grating structure uses a metal material at present, so that the one-dimensional terahertz grating structure has low visible light transmittance and poor flexibility, and in practical application, various requirements are imposed on grating optical devices, so that a flexible conductive grating material capable of realizing ultra-wideband transparency of a visible-infrared-terahertz waveband needs to be provided, and the material has a great potential application value.

Disclosure of Invention

In order to overcome the defects that a common terahertz metal grating structure is usually lack of flexibility and low in optical frequency transmittance, the invention provides a flexible conductive composite metal nanowire grating material which has high optical transmittance and good conductivity for terahertz, infrared and visible light ultra-broadband. Further discloses a preparation method of the flexible conductive composite metal nanowire grating material. The specific technical scheme is as follows:

the first scheme is as follows: the flexible conductive composite metal nanowire grating material is characterized by comprising a polydimethylsiloxane flexible substrate, a metal nanowire grating located on the flexible substrate, and a silicon dioxide layer located between the metal nanowire grating and the flexible substrate.

As a preferable scheme, the metal nanowire grating is a silver nanowire grating.

As a preferable scheme, the diameter of the silver nanowires in the silver nanowire grating is 100-300 nm.

As a preferable scheme, the period of the metal nanowire grating is 30-3000 microns, wherein the ratio of the groove width of the grating to the period is 5% -60%.

As a preferable scheme, the coverage rate of the nanowires in the metal nanowire grating is 18% to 63%.

Preferably, the thickness of the flexible substrate is 10-100 micrometers.

As a preferred scheme, the thickness of the silicon dioxide layer is 0.5-5 um.

Scheme II: a method for preparing a flexible conductive composite metal nanowire grating material is used for preparing the flexible conductive composite metal nanowire grating material in the first scheme and the preferred scheme thereof, and comprises the following steps:

step 1, dropwise adding a metal nanowire ethanol dispersion liquid on a terahertz metal grating template, and performing spin coating and drying to form at least one layer of metal nanowire grating structure;

step 2, heating the terahertz metal grating template with the metal nanowire grating structure in a constant temperature box at 200-300 ℃ for 2-3 hours;

step 3, dropwise adding a silicon dioxide ethanol dispersion liquid on the metal nanowire grating structure, and forming a silicon dioxide layer on the metal nanowire grating structure after spin coating and drying;

step 4, mixing the materials in a mass ratio of 20: 1-5: 1, dripping the mixed liquid of polydimethylsiloxane and a curing agent on the surface of the silicon dioxide layer to obtain a polydimethylsiloxane/silicon dioxide aerogel/metal nanowire structure, and stripping the polydimethylsiloxane/silicon dioxide aerogel/metal nanowire structure from a terahertz metal grating template after the polydimethylsiloxane/silicon dioxide aerogel/metal nanowire structure is cured to obtain a metal nanowire-polydimethylsiloxane composite structure;

and 5, plating metal electrodes on the periphery of the grating of the composite structure to obtain the flexible conductive composite metal nanowire grating material.

Preferably, in step 3, the solute of the silica ethanol dispersion liquid is fumed nano silica, and the content of the fumed nano silica is 2-10%.

As a preferable scheme, in the step 1 and the step 3, the drying temperature is 20-60 ℃, and the drying time is 5-30 minutes.

As a preferable scheme, in the step 4, the curing temperature is 60-100 ℃, and the curing time is 1-2 hours.

The invention has the following beneficial effects:

1) the flexible conductive composite metal nanowire grating material disclosed by the invention is a transparent flexible foldable material, has high transmittance in a visible-infrared-terahertz waveband ultra wide band, has good conductive performance, can still keep stable optical properties when electrified, and can be applied to more application fields.

2) The terahertz metal grating template is adopted to spin-coat the metal nanowires, so that a complete and uniform metal nanowire grating structure can be obtained, and the high transmittance in the terahertz waveband is ensured.

3) Dimethyl siloxane is used as a substrate material of the metal nanowire grating, so that the metal nanowire grating has good flexibility, and high transmittance of visible light and infrared bands can be guaranteed even if the metal nanowire grating is bent and electrified.

4) The silver nanowire is used as a grating preparation material, so that the photoelectric property is excellent, the room-temperature film forming condition and the low-melting-point flexible substrate have good compatibility, the preparation process is simple, and the cost is low.

5) The preparation method of the flexible conductive composite metal nanowire grating material provided by the invention uses an imprinting process, can be manufactured by adopting simple equipment (such as a glue throwing table and a dryer), is simple in process operation, safe and non-toxic, is low in realization cost, and has wide application prospect and popularization value.

Drawings

FIG. 1 is a schematic structural diagram of a flexible conductive composite metal nanowire grating material;

fig. 2 is a flow chart of a process for preparing a flexible conductive composite metal nanowire grating material, wherein: the upper row is a front view, and the lower row is a side view;

FIG. 3 is a diagram of a flexible conductive composite metal nanowire grating material;

fig. 4 is a schematic diagram of transmittance of the conductive composite metal nanowire grating material in visible-infrared-terahertz wave bands under different voltages, wherein: (a) the transmittances of visible band samples under the condition that currents of 0 milliampere, 20 milliampere and 50 milliampere are added respectively, (d) the transmittance of infrared band samples under the condition that currents of 0 milliampere, 20 milliampere and 50 milliampere are added respectively, and (g) the transmittance of terahertz band samples under the conditions that currents of 0 milliampere, 20 milliampere and 50 milliampere are added respectively;

the attached drawings are marked as follows: the device comprises a 1-silver nanowire grating, a 2-silicon dioxide thin film layer, a 3-polydimethylsiloxane flexible substrate and a 4-terahertz metal grating template.

Detailed Description

On the basis of the traditional one-dimensional terahertz metal grating, the invention adopts a flexible material Polydimethylsiloxane (PDMS) as a substrate and a metal nanowire as a grating preparation material, namely, the composite metal nanowire is adopted to replace a block metal raw material in the prior art. In the manufacturing process, firstly, a silver nanowire grating structure is prepared by utilizing a terahertz metal grating template, then polydimethylsiloxane is directly coated on the silver nanowire grating structure to prepare a metal nanowire-polydimethylsiloxane composite structure, and then the metal nanowire-polydimethylsiloxane composite structure is peeled off to obtain the flexible conductive composite metal nanowire grating material. Wherein, the polydimethylsiloxane is a high molecular organic silicon compound, has optical transparency and biocompatibility, and has a fast and simple manufacturing process, and the embodiment adopts the film-shaped polydimethylsiloxane as a substrate material and also has good flexibility. Considering that the silver nanowire has excellent photoelectric properties, high transmittance and conductivity, and relatively low cost of raw materials, the preparation process generally adopts a fast and low-cost liquid phase method, and the room temperature film forming condition has good compatibility with the low-melting point flexible substrate, the following embodiment prefers the silver nanowire as the preparation material of the grating.

Referring to fig. 1, embodiment 1 discloses a transparent flexible conductive composite metal nanowire grating material, which includes a polydimethylsiloxane flexible substrate 3, a silver nanowire grating 1 formed on the polydimethylsiloxane flexible substrate 3, and a silicon dioxide thin film layer 2 interposed between the silver nanowire grating 1 and the polydimethylsiloxane flexible substrate 3.

The period of the metal nanowire grating is 30-3000 micrometers, the optimal proportion of the width of the grating groove to the period of the grating is 5% -60%, and the metal nanowire grating can be designed according to a wave band required to respond.

Wherein, the coverage rate of the silver nanowires in the silver nanowire grating is preferably 18-63%.

Generally, the higher the coverage rate is, the higher the terahertz light transmittance is, the higher the conductivity is, but the visible light transmittance is reduced; on the contrary, the terahertz transmittance is reduced, the conductivity is reduced, and the transmittance near visible light is increased. Therefore, the coverage of the silver nanowires and the corresponding manufacturing process can be designed according to specific application requirements.

Wherein, the polydimethylsiloxane flexible substrate 3 can be 10-100 microns. The flexible substrate is too thin, so that the finally prepared grating material is easy to damage due to the too thin thickness, and the preparation process is relatively more difficult, so that a relatively proper substrate thickness needs to be selected.

Wherein, the thickness of the silicon dioxide film layer 2 is about micron order, for example 0.5-5 um. The silicon dioxide film layer 2 is covered on the substrate, and is mainly used for combining the silver nanowire grating 1 with the polydimethylsiloxane flexible substrate 3, because the silver nanowire grating is not easy to attach to the polydimethylsiloxane flexible substrate, the combination performance of the silver nanowire grating and the polydimethylsiloxane flexible substrate is not ideal, the combination performance of the silicon dioxide, the silver nanowire grating and the polydimethylsiloxane is good, and the silicon dioxide, the silver nanowire grating and the polydimethylsiloxane are used as buffer layers of the silicon dioxide and the polydimethylsiloxane, so that the combination of the silicon dioxide and the silver nanowire grating is realized, and the performance of the final grating material is not influenced. In addition, the covering silicon dioxide can be used for fixing and protecting the silver nanowires at the same time, and the silver nanowire layer is prevented from being damaged too much when the silver nanowires are transferred.

The flexible conductive composite metal nanowire grating material has the following characteristics: 1) flexibility; 2) the ultra-wideband high transmittance of the visible-infrared-terahertz wave band; 3) good conductive performance; 4) has stable optical properties when energized.

With reference to fig. 2, embodiment 2 discloses a method for preparing a flexible conductive composite metal nanowire grating material, which can be used to prepare the flexible conductive composite metal nanowire grating material described in embodiment 2, and specifically includes the following steps:

step 1, manufacturing a metal nanowire grating

Uniformly dropwise adding a silver nanowire absolute ethyl alcohol dispersion liquid on a clean terahertz metal grating template (hereinafter referred to as a grating template, as shown in fig. 2 (a)), carrying out spin coating on a spin coating table at a rotating speed of 600 plus 2000 revolutions per minute (for example, 1100 revolutions per minute) to form a layer of silver nanowire network substrate with uniform appearance, and then placing the grating template coated with the silver nanowire transparent grating in a constant temperature box at 60 ℃ for 10 minutes for drying to obtain a layer of silver nanowire transparent grating. Repeating the steps for six times to obtain the silver nanowire transparent grating formed by overlapping six layers.

The grating period in the grating template is 510 microns, the width of the slits for forming the grating is 300 microns, and the distance between adjacent slits is 210 microns. Of course, the grating period and the slit width of the grating template can be adjusted according to the frequency to which the grating needs to respond.

The drying temperature can be 20-60 ℃ in specific application, the drying time can be 5-30 minutes, and other drying temperatures can be adopted as long as the drying target can be realized and the performance of the final grating material is not affected.

The diameter of the silver nanowires in the silver nanowire grating is preferably 100-300 nm, and the specification of the silver nanowire ethanol dispersion liquid can be 5 mg/ml. The number of layers of the silver nanowires prepared by spin coating can be designed according to requirements, more than one layer can be the same, the number of layers of spin coating is more, the coverage rate of the silver nanowires is higher, and the light transmittance and the electric conductivity can be changed, which is described in embodiment 1, and the silver nanowires can be specifically designed according to light which needs to respond.

Step 2, carrying out heat treatment and electric conduction treatment on the metal nanowire grating

Putting the grating template (shown in fig. 2 (b)) with the silver nanowire transparent grating on the surface obtained in the step 1 into an incubator for heat treatment, and heating at 200 ℃ for 3 hours, wherein the heating is heat treatment and conductive treatment, and the purpose of the heating is mainly to enable the silver nanowires to be combined more tightly.

Wherein, the temperature of the heat treatment can be 200-300 ℃, and the time can be 2-3 hours.

Step 3, preparing the silicon dioxide/silver nanowire transparent grating

And dropwise adding the silicon dioxide ethanol dispersion liquid on the silver nanowire transparent grating subjected to the heat treatment till the whole grating is completely covered, then placing the grating on a glue homogenizing table, obtaining the silicon dioxide/silver nanowire transparent grating at the rotating speed of 600 plus 2000 revolutions per minute (for example, 1100 revolutions per minute), and placing the grating in a constant temperature box at 60 ℃ for heating for 10 minutes for drying.

The silicon dioxide film layer prepared by the gas phase covering process can increase the conductivity of the silicon dioxide film layer to a certain extent without influencing the grating transmittance, but the preparation process is not limited to this.

Wherein, the solute of the silicon dioxide ethanol dispersion liquid is gas-phase nano silicon dioxide, the solvent is mainly ethanol, the content of the gas-phase nano silicon dioxide is preferably 2-10%, and the content in the embodiment is 4%.

The drying temperature can be 20-60 ℃ in specific application, the drying time can be 5-30 minutes, and other drying temperatures can be adopted as long as the drying target can be realized and the performance of the final grating material is not affected.

Step 4, preparing the composite metal nanowire grating material

Using an american-do-coming 184 silicone rubber, a silicone rubber was prepared by mixing a prepolymer (dimethylsiloxane) and a curing agent (e.g., hydrogen-containing silicone oil) in a mass ratio of 10: 1, uniformly mixing to obtain polydimethylsiloxane, dripping the polydimethylsiloxane onto the surface of the grating template until the polydimethylsiloxane completely covers the whole template surface, spin-coating at the rotating speed of 600 plus 2000 rpm (for example, 600 rpm) to obtain a polydimethylsiloxane/silicon dioxide aerogel/silver nanowire structure (as shown in fig. 2 (c)), curing at 60 ℃ for 3 hours, and then stripping the structure from the metal grating template to obtain a flexible metal nanowire-polydimethylsiloxane composite structure (as shown in fig. 2 (d)).

Wherein, the curing temperature can be 60-100 ℃, the curing time is 1-2 hours, and certainly, the curing can be carried out at lower temperature, and the curing time is correspondingly prolonged.

Step 5, preparing the conductive composite metal nanowire grating material

And (4) plating metal electrodes on the periphery of the grating of the flexible metal nanowire-polydimethylsiloxane composite structure obtained in the step (4), and thus preparing the visible-infrared-terahertz waveband ultra-wideband transparent flexible conductive composite metal nanowire grating material required by the target.

The metal electrode can be made of metal materials such as copper, aluminum, gold and the like, and can be selected according to requirements.

Next, a sample of the flexible conductive composite metal nanowire grating material prepared in example 2 was tested, and its performance characteristics were as follows:

from the physical performance parameters, the silver nanowire transparent grating has good conductivity, and the resistivity of the silver nanowire transparent grating is measured to be about 1.64 multiplied by 10^-5Ohm-meter. The structure is flexible and can be bent greatly, and the area coverage ratio of the silver nanowires is not higher than 58.6%. From the optical performance test results, as shown in fig. 3, the structure has good optical frequency band macroscopic transmittance; as shown in fig. 4, the structure has high transmittance in the conductive state of terahertz, infrared and visible light ultra-broadband, and the measured spectra under the condition of adding currents of 0 milliampere, 20 milliampere and 50 milliampere show that the sample can obtain the same broadband high transmittance when not adding electricity. Therefore, the ultra-wideband transparent flexible conductive composite metal nanowire grating with the visible-infrared-terahertz waveband has excellent photoelectric performance.