Adjustable light absorption piece based on vertical type micro-nano graphene sheet and preparation method of adjustable light absorption piece

Abstract

The invention belongs to the field of optical function nanometer materials, and particularly relates to an adjustable light absorption piece based on a vertical type micro-nano graphene sheet and a preparation method of the adjustable light absorption piece. According to the method, growth parameters such as temperature, time, gas flow and radio frequency power of radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) equipment are adjusted; the microstructure and the size of the upright micro-nano graphene sheet are changed, and the light absorption performance of the light absorption sheet is regulated and controlled. The adjustable light absorption piece is simple in preparation process and low in cost, does not need a catalyst and has the characteristic of low-temperature preparation, the light absorption rate of the adjustable light absorption piece reaches up to 99% or above, and the structure that the upright graphene film is clamped by the double-layer transparent base material also protects graphene, so that the adjustable light absorption piece has the characteristics of scratch resistance and repeated use.

Description

Technical Field

[0001] The invention belongs to the field of optical functional nano materials, and in particular relates to an adjustable light absorbing sheet based on upright micro-nano graphene sheets and a preparation method thereof. Background Art

[0002] With the rapid development of science and technology, the demand for high-performance light-absorbing materials is growing in the fields of optoelectronic devices, solar thermal conversion technology, and photoelectrocatalysis technology. The performance of light-absorbing materials directly affects the efficiency of photoelectric conversion and photothermal conversion. Therefore, the research and development of light-absorbing materials with high absorbance, tunability, and low cost has become a current research hotspot.

[0003] As a new type of two-dimensional material, graphene has attracted widespread attention due to its unique electronic, thermal and optical properties. In particular, vertical graphene (VG), due to its characteristic of growing vertically to the substrate, exhibits excellent optical properties, including high absorbance and wide-band light absorption ability. However, traditional vertical graphene preparation methods, such as chemical vapor deposition (CVD) and plasma enhanced chemical vapor deposition (PECVD), usually need to be carried out under high temperature conditions and rely on catalysts, which limits its application in large-scale production and cost-effectiveness. At the same time, the light absorption properties of vertical graphene prepared by these methods are often fixed, and it is difficult to flexibly adjust according to specific application requirements. In addition, as a thin film material, vertical graphene is easy to damage and scratch. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing an adjustable light absorbing sheet based on upright micro-nano graphene sheets, and to achieve the control of the light absorbing performance of the light absorbing sheet by changing the microscopic morphology and structure of the upright graphene.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] An adjustable light absorbing sheet based on upright micro-nano graphene sheets comprises a first transparent substrate, a second transparent substrate, and upright graphene formed between the first transparent substrate and the second transparent substrate; the microscopic morphology of the upright graphene is arranged upright, and the light absorbing performance is adjustable by adjusting the parameters of the upright graphene nanosheets, wherein the parameters include microscopic morphology, height, thickness, spacing, etc.

[0007] The method for preparing the above-mentioned adjustable light absorbing sheet based on upright graphene comprises the following steps:

[0008] Step 1, cleaning and drying the transparent substrate, wherein the transparent substrate includes a first transparent substrate and a second transparent substrate;

[0009] Step 2, placing the first transparent substrate into a vacuum chamber of a radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) device, and evacuating the chamber until the vacuum requirement is met; then heating and heat-insulating the first transparent substrate, with the heating temperature ranging from 25° C. to 550° C.;

[0010] Step 3, introducing a certain amount of buffer gas into the vacuum chamber and maintaining the gas pressure between 0.01Pa and 1000Pa; the gas flow rate of the buffer gas is between 1sccm and 1000sccm;

[0011] Step 4, turning on the radio frequency source of the RF-PECVD device, using plasma enhanced chemical vapor deposition technology, growing upright graphene with microscopic nanosheets in an upright arrangement structure on the surface of the first transparent substrate and then taking it out; during the growth process, the radio frequency power is 10W to 5000W, and the upright graphene growth time is 5min to 180min;

[0012] Step 5: Cover the second transparent substrate on the first transparent substrate on which the upright graphene is grown, and use a conductive adhesive to fix the edge of the substrate, thereby obtaining an adjustable light absorbing sheet based on the upright graphene.

[0013] Furthermore, the transparent substrate is electronic glass, quartz glass or conductive glass.

[0014] Furthermore, the buffer gas in step 3 is argon, methane, hydrogen or a mixture thereof.

[0015] Furthermore, the adhesive in step 5 includes graphite conductive glue, conductive silver paste, epoxy resin conductive glue or glass glue.

[0016] Furthermore, in step 5, when the conductive adhesive is used to fix the edge of the substrate, room temperature curing or heating curing is adopted.

[0017] The adjustable light absorbing sheet and preparation method thereof proposed by the present invention, the light absorbing material of the light absorbing sheet is an upright micro-nano graphene sheet structure, and the principle is as follows: the microstructure of the upright graphene is an irregularly distributed graphene nanosheet arranged upright, the top of the nanosheet is a single layer or a few layers of graphene, and the middle and bottom of the nanosheet are multilayer graphene. Due to the high light transmittance of the single layer or a few layers of graphene, light can enter the micro-nano structure through the top of the nanosheet. Multilayer graphene has an absorption effect on light. Since the graphene nanosheet is an irregularly distributed upright arrangement, light will be diffusely reflected multiple times inside the upright graphene, and then absorbed by the multilayer graphene in the middle and bottom of the upright graphene. Since the upright graphene is an upright arranged graphene nanosheet, its specific surface area is much larger than that of the multilayer graphene in the plane, so the absorption area and absorptivity can be greatly increased.

[0018] Based on the above principle, the present invention adjusts the growth parameters of the radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) equipment, such as temperature, time, gas flow rate and radio frequency power, to change the size of the microscopic morphology of the upright graphene, thereby achieving the regulation of the light absorption performance of the light absorbing sheet. Compared with the prior art, the adjustable light absorbing sheet of the present invention has a simple preparation process, low cost, and does not require a catalyst. It has the characteristics of low-temperature preparation, and its light absorption rate is as high as more than 99%. The structure of the double-layer transparent substrate sandwiching the upright graphene film also protects the graphene, making it scratch-resistant and reusable. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the principle of the present invention based on the upright graphene tunable light absorbing sheet;

[0020] Figure 2 The top view and cross-sectional view of the upright graphene prepared in Example 1 are shown in FIG. a. The top view is shown in FIG. b. The cross-sectional view is shown in FIG.

[0021] Figure 3 The top view and cross-sectional view of the upright graphene prepared in Example 2 are shown in FIG. a. The top view is shown in FIG. b. The cross-sectional view is shown in FIG.

[0022] Figure 4 The top view and cross-sectional view of the upright graphene prepared in Example 3 are obtained by scanning electron microscopy; a is the top view under scanning electron microscopy, and b is the cross-sectional view;

[0023] Figure 5 Schematic diagram of the three-dimensional structure of the light absorbing sheet of the present invention;

[0024] Figure 6 The absorbance diagram of the light absorbing sheets obtained in Examples 1, 2 and 3 is shown.

[0025] Reference numerals:

[0026] 1 is a transparent substrate, and 2 is an upright graphene film.

[0027] Specific embodiment

[0028] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0029] Embodiment 1

[0030] like Figure 1 As shown, the present embodiment provides a method for preparing an adjustable light absorbing sheet based on an upright micro-nano graphene sheet structure, comprising:

[0031] Step 1: Select two pieces of electronic glass with a size of 20 mm*20 mm*1 mm as substrates, clean and dry them for later use, and the two transparent substrates are respectively a first transparent substrate and a second transparent substrate.

[0032] Step 2: Place the first transparent substrate processed in step 1 into the vacuum chamber of the RF-PECVD device, and then heat the first transparent substrate to room temperature 25° C. and maintain the constant temperature.

[0033] Step 3: introduce 20 sccm of argon and methane mixed gas into the vacuum chamber containing the first transparent substrate, so that the pressure in the chamber is maintained at 50 Pa.

[0034] Step 4, turn on the RF source of the RF-PECVD equipment to perform plasma enhanced chemical vapor deposition, set the RF source power to 2000W, and the growth time of the upright graphene to 30min. The height of the formed upright graphene is about 2um, and the size of the graphene nanosheet is between 300-400nm. The top view of the upright graphene under the scanning electron microscope is as follows: Figure 2 The scanning electron microscope cross-section is shown in a. Figure 2 As shown in b.

[0035] Step 5: Cover the second transparent substrate on the electronic glass substrate with upright graphene, and sandwich the upright graphene between the two electronic glass substrates to form a Figure 5 The structure shown in the figure. Use graphite conductive glue to fix the two opposite edges of the substrate, place it in an environment with a temperature of 25-30°C for 12-24 hours, then heat it to 80°C and keep it at a constant temperature for 2 hours, then heat it to 120°C and keep it at a constant temperature for 2 hours, and then slowly cool it to obtain an adjustable light-absorbing sheet based on upright graphene.

[0036] Step 6: Use a spectrometer to measure the reflection and transmission of visible light on the prepared upright graphene, and obtain the absorbance of the sample between 400nm and 800nm, which is greater than 87.86%.

[0037] Embodiment 2

[0038] The preparation steps of this embodiment are the same as those of the first embodiment, except that:

[0039] Step 1: When growing upright graphene, the temperature of the first transparent substrate is first heated to 300° C. and kept for 15 minutes, then heated to 400° C. and kept for 5 minutes, and then upright graphene is grown at a substrate temperature of 400° C. The segmented heating and heat preservation makes the substrate heated more evenly, which is conducive to the uniform growth of upright graphene and improves the quality of the upright graphene layer.

[0040] The top view of the upright graphene sheet obtained in this example is shown in the scanning electron microscope. Figure 3 a, the cross-sectional view is shown in Figure 3 As shown in b; Figure 3 a and Figure 3b It can be seen that the upright graphene sheets obtained by adjusting the temperature of the first transparent substrate, the heat preservation time, and the staged heating are larger and taller than the upright graphene sheets of Example 1. The height of the upright graphene is about 1.2um, and the size of the graphene nanosheet is between 400-600nm. The light absorption rate of the light absorbing sheet at a wavelength of 400nm-800nm ​​is greater than 92.29%.

[0041] Embodiment 3

[0042] The preparation steps of this embodiment are the same as those of the first embodiment, except that:

[0043] Step 1: When growing upright graphene, the substrate temperature is first heated to 300°C and kept for 15 minutes, then heated to 540°C and kept for 5 minutes, and then upright graphene is grown at a substrate temperature of 540°C. The segmented heating and heat preservation makes the substrate heated more evenly, which is conducive to the uniform growth of upright graphene and improves the quality of the upright graphene layer.

[0044] Scanning electron microscope top view Figure 4 a, the cross-sectional view is shown in Figure 4 As shown in b; Figure 4 a and Figure 4 b It can be seen that after adjusting the temperature and holding time of the first transparent substrate, the upright graphene sheets obtained are larger and taller than the upright graphene sheets of Example 1. The height of the upright graphene is about 2.3um, and the size of the graphene nanosheets is between 600-800nm. The light absorption rate of the light absorption sheet at a wavelength of 400nm-800nm ​​is greater than 99.03%, and the maximum light absorption rate can reach 99.83%.

[0045] Figure 6 The absorbance diagram of the light absorbing sheet obtained in Examples 1, 2 and 3. Figure 6 It can be seen that the absorbance of the upright graphene light absorbing sheet gradually increases from Example 1 to Example 3. Figure 1-5 It can be seen that changing the preparation parameters can change the microstructure of upright graphene, thereby affecting the change of its absorbance.

[0046] In summary, the present invention achieves the change of the microscopic morphology and size of upright graphene by changing the preparation parameters in the preparation process, thereby achieving the purpose of regulating the light absorption performance of the light absorbing sheet. In addition, upright graphene, as a thin film material, has the characteristics of being easy to damage and scratch, and the upright graphene film is protected by the provision of the first transparent substrate and the second transparent substrate in the structure of the present invention, so that it has good environmental stability. The graphene film prepared under low temperature conditions has a highly uniform and orderly structure, which can maintain a consistent light absorption effect in multiple experiments and has repeatability. The light absorption rate of the light absorbing sheet can also be adjusted according to different application requirements, providing a high-performance light absorbing material solution for optoelectronic device equipment, solar thermal conversion, and photoelectric catalytic technology.

Claims

1. An adjustable light absorbing sheet based on upright micro-nano graphene sheets, comprising a first transparent substrate, a second transparent substrate, and upright graphene formed between the first transparent substrate and the second transparent substrate; characterized in that: The microscopic morphology of the upright graphene is arranged upright, and the light absorption performance can be adjusted by adjusting the parameters of the upright graphene nanosheets, wherein the parameters include the microscopic morphology, height, thickness and spacing.

2. A method for preparing an adjustable light-absorbing sheet based on upright micro-nano graphene sheets, characterized in that: The following steps are involved: Step 1, cleaning and drying the transparent substrate, wherein the transparent substrate includes a first transparent substrate and a second transparent substrate; Step 2, placing the first transparent substrate into a vacuum chamber of a radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) device, and evacuating the chamber until the vacuum requirement is met; then heating and heat-insulating the first transparent substrate, with the heating temperature ranging from 25° C. to 550° C.; Step 3, introducing a certain amount of buffer gas into the vacuum chamber and maintaining the gas pressure between 0.01Pa and 1000Pa; the gas flow rate of the buffer gas is between 1sccm and 1000sccm; Step 4, turning on the radio frequency source of the RF-PECVD device, using plasma enhanced chemical vapor deposition technology, growing upright graphene with microscopic nanosheets in an upright arrangement structure on the surface of the first transparent substrate and then taking it out; during the growth process, the radio frequency power is 10W to 5000W, and the upright graphene growth time is 5min to 180min; Step 5: Cover the second transparent substrate on the first transparent substrate on which the upright graphene is grown, and use a conductive adhesive to fix the edge of the substrate, thereby obtaining an adjustable light absorbing sheet based on the upright graphene.

3. The method for preparing an adjustable light absorbing sheet based on an upright micro-nano graphene sheet structure according to claim 2, characterized in that: The transparent substrate is electronic glass, quartz glass or conductive glass.

4. The method for preparing an adjustable light absorbing sheet based on an upright micro-nano graphene sheet structure according to claim 2, characterized in that: The buffer gas in step 3 is argon, methane, hydrogen or a mixture thereof.

5. The method for preparing an adjustable light absorbing sheet based on an upright micro-nano graphene sheet structure according to claim 2, characterized in that: The adhesive in step 5 includes graphite conductive glue, conductive silver paste, epoxy resin conductive glue or glass glue.

6. The method for preparing an adjustable light absorbing sheet based on an upright micro-nano graphene sheet structure according to claim 2, characterized in that: When the conductive adhesive is used to fix the edge of the substrate in step 5, room temperature curing or heating curing is adopted.

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