Selective light absorption material with three-dimensional grid structure and preparation method thereof

Abstract

The invention relates to the technical field of material preparation, and provides a selective light absorption material with a three-dimensional grid structure and a preparation method thereof, and the preparation method comprises the following steps: carrying out heavy ion irradiation on a polymer template to obtain a polymer template containing a latent track structure; carrying out ultraviolet etching on the polymer template containing the latent track structure; performing electrochemical metal deposition on the polymer template subjected to ultraviolet etching to obtain a three-dimensional grid-polymer composite structure filled with metal nanowires; and dissolving the three-dimensional grid-polymer composite structure filled with the metal nanowires to obtain the selective light absorption material with the three-dimensional grid structure. The selective light absorption material is endowed with excellent properties of high visible light absorption and low near-infrared emission, and has remarkable advantages in large-scale preparation and application suitability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material preparation, and particularly relates to a selective light-absorbing material with a three-dimensional grid structure and a preparation method thereof. BACKGROUND

[0002] A selective light-absorbing material is a kind of special functional material capable of realizing high-efficiency absorption of light of a specific waveband (such as visible light and infrared light) and having low transmittance or reflectivity for light of other wavebands, and has important application value in the fields of space exploration, infrared stealth, photoelectric conversion and the like. In the field of space exploration, strict requirements are put forward for the optical properties of the material: high absorption rate in the visible light waveband (about 400-760 nm) is required to suppress stray light interference and improve the imaging accuracy of a space optical detector; and low emissivity in the infrared waveband (about 760 nm-1 mm) is required to reduce thermal radiation loss and guarantee the stability and reliability of the detector in an extreme temperature difference environment.

[0003] In recent years, nanostructured materials have become a research hotspot in this field due to their unique optical modulation characteristics. The interaction between a nano-scale metal structure (such as a nanoparticle, a nanowire, a nanonetwork or the like) and incident light can excite a localized surface plasmon resonance (LSPR) effect, forming a localized enhanced electric field and significantly improving the light absorption efficiency. Compared with a single metal nanoparticle, a metal nanonetwork structure has more advantages in optical response modulation due to its three-dimensional network characteristics: on the one hand, the inherent LSPR effect retains the selective absorption ability of the metal nanostructure for light of a specific waveband; on the other hand, the resonance cavity formed by the intersection of nanowires of different sizes in the network can further enhance absorption through size matching effect, and the synergistic effect of the two is expected to realize high light absorption. In addition, for light in the infrared waveband, the characteristic size of the metal nanostructure is much smaller than the wavelength, which approximates the surface of the structure to the surface of a bulk metal and exhibits strong infrared reflection, i.e. low infrared absorption rate. Therefore, the metal nanonetwork structure with precise spectral modulation has important application potential in the field of selective light absorption.

[0004] However, the currently common selective light absorption materials mainly include intrinsic materials, multi-layer structures, metal ceramic composite structures, etc. The optical absorption characteristics of the intrinsic material are mainly determined by the energy band structure of the material itself, and the regulation of the energy band structure often needs complex chemical doping or lattice modification, and the regulation range is limited, which is difficult to meet the precise absorption demand of multi-band (especially visible light-infrared cross-band). The multi-layer structure and the metal ceramic composite structure can theoretically optimize the performance of the visible light absorption functional layer and the infrared reflection functional layer by physically separating them. However, the design of such structure depends on the stack architecture of the infrared reflection layer (usually a metal film) and the visible light absorption layer (such as a semiconductor or a metal oxide), and the realization of low infrared emissivity highly depends on the strong reflection of the underlying metal to infrared light. Moreover, the infrared reflectivity of the metal film is positively correlated with its thickness, while the thickness of the visible light absorption layer needs to be much smaller than the visible light wavelength (usually only tens of nanometers) to avoid additional reflection loss of infrared light. This contradiction limits the thickness of the visible light absorption layer, making it difficult to improve the absorption rate by increasing the thickness, and ultimately causing the problem of insufficient visible light absorption efficiency, which cannot meet the urgent demand for high-performance selective light absorption materials in the field of aerospace. SUMMARY

[0005] The present application provides a selective light absorption material with a three-dimensional grid structure and a preparation method thereof, which solves the above technical defects in the prior art, and endows the selective light absorption material with excellent performance of high visible light absorption and low near-infrared emission, and has significant advantages in large-scale preparation and application adaptability.

[0006] The first aspect of the present application provides a preparation method of a selective light absorption material with a three-dimensional grid structure, comprising the following steps: irradiating a polymer template with heavy ions to obtain a polymer template containing latent track structures; ultraviolet etching the polymer template containing latent track structures; electrochemically depositing metal on the ultraviolet etched polymer template to obtain a three-dimensional grid-polymer composite structure filled with metal nanowires; dissolving the three-dimensional grid-polymer composite structure filled with metal nanowires to obtain a selective light absorption material with a three-dimensional grid structure.

[0007] According to the preparation method of the selective light absorption material with a three-dimensional grid structure provided by the present application, the polymer template includes polyethylene terephthalate or polycarbonate, and the thickness of the polymer template is less than 30 µm.

[0008] According to the preparation method of the selective light absorption material with a three-dimensional grid structure provided by the present application, the power of the ultraviolet light source used for ultraviolet etching is 5 mW·cm −2up to 100 mW·cm −2 .

[0009] The preparation method of the selective light-absorbing material with the three-dimensional grid structure provided by the application has a time of 10 min to 10 h for the ultraviolet etching.

[0010] The preparation method of the selective light-absorbing material with the three-dimensional grid structure provided by the application has a time of 10 min to 10 h for the ultraviolet etching. The gold with a thickness of 10 nm to 50 nm is sprayed on one side of the polymer template to serve as an electrode; The polymer template is deposited with a substrate using a direct current voltage and then deposited with a three-dimensional grid structure using a pulse voltage.

[0011] The second aspect of the application provides a selective light-absorbing material with a three-dimensional grid structure, which is prepared by any one of the preparation methods, and the three-dimensional grid structure of the material is composed of a metal deposition phase and a void after etching of a polymer template, and the material has selective absorption characteristics for specific wavelengths of light.

[0012] The selective light-absorbing material with the three-dimensional grid structure provided by the application has an average absorption rate of greater than 98% in a wavelength range of 300 nm to 800 nm.

[0013] The selective light-absorbing material with the three-dimensional grid structure provided by the application has an average absorption rate of less than 30% in a near-infrared wavelength range of 5 μm to 20 μm.

[0014] The selective light-absorbing material with the three-dimensional grid structure provided by the application has a characteristic size of less than or equal to 10 nm.

[0015] The preparation method of the selective light-absorbing material with the three-dimensional grid structure provided by the application has a time of 10 min to 10 h for the ultraviolet etching.

[0016] The embodiment of the present application adopts a polymer film (such as PC) as a substrate, which has high flexibility and low-cost roll-to-roll processing characteristics, and is suitable for large-area continuous production requirements; meanwhile, the heavy ion irradiation and the ultraviolet etching process have strong compatibility with polymer types, and the metal deposition step can be adapted to gold, silver, copper and other metals by adjusting the electrolyte formula, thereby breaking through the strict limitation of the substrate material in the traditional technology (such as only applicable to radiation-resistant high polymers). The large-area production capacity reduces the unit area cost, and the material types can be expanded to different application scenarios (such as aerospace, optoelectronics and stealth).

[0017] The embodiment of the present application realizes that the feature size (pore, line width) of the three-dimensional grid structure is controllable to be less than 10 nm through the latent track guiding mechanism induced by heavy ion irradiation, combined with the directional dissolution of ultraviolet etching and the directional growth of nanowires by electrochemical deposition. This ultra-fine structure directly determines the breakthrough of the optical performance: The grid pore and the nanowire diameter form a strong coupling with the visible light wavelength, excite a significant localized surface plasmon resonance (LSPR) effect, form a dense local enhanced electric field, and greatly improve the light absorption efficiency, so that the visible light absorption rate is high, that is, the average absorption rate of 300 nm-800 nm is greater than 98%.

[0018] The continuous conductivity of the metal grid dominates the free electron gas oscillation in the infrared waveband, and reflects the infrared photons; meanwhile, the pore size of less than 10 nm is much smaller than the infrared wavelength (5-20 mu m), which avoids the scattering loss of infrared light, and finally realizes the infrared low absorption characteristic, so that the near-infrared absorption rate is low, and the absorption rate of 5-20 mu m is less than 30%.

[0019] Therefore, through the synergistic innovation of process simplification, material universality expansion and feature size precise control, the embodiment of the present application solves the core defects of the prior art in efficiency, cost and precision, finally endows the selective light absorption material with excellent performance of high visible light absorption and low near-infrared emission, and has a significant advantage in scalability and application adaptability. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0021] Figure 1 It is a flow chart of the preparation method of the selective light absorption material with a three-dimensional grid structure provided by the embodiment of the present application.

[0022] Figure 2is a scanning electron microscope (SEM) image of the selective light-absorbing material with a three-dimensional grid structure prepared in Example 1 of the present application; wherein (a) is an overall morphology image of the material at a magnification of 10 microns, for showing the macroscopic distribution characteristics of the three-dimensional grid structure; (b) is a local detail image of the material at a magnification of 1 micron, for presenting the microscopic morphology and size characteristics of the grid units.

[0023] Figure 3 is a transmission electron microscope (TEM) image of the selective light-absorbing material with a three-dimensional grid structure prepared in Example 1 of the present application, for directly showing the microscopic characteristics of the three-dimensional grid structure inside the material (such as the connectivity of the grid units, the pore distribution, or the interface morphology of the metal deposition phase and the polymer template, etc.).

[0024] Figure 4 is an optical photograph of the selective light-absorbing material with a three-dimensional grid structure prepared in Example 1 of the present application.

[0025] Figure 5 is the absorption spectrum of the selective light-absorbing material with a three-dimensional grid structure prepared in Example 1 of the present application in the visible-to-middle far infrared waveband.

[0026] Figure 6 is a scanning electron microscope (SEM) image of the selective light-absorbing material with a three-dimensional grid structure prepared in Example 2 of the present application at a magnification of 1 micron.

[0027] Figure 7 is a transmission electron microscope (TEM) image of the selective light-absorbing material with a three-dimensional grid structure prepared in Example 2 of the present application. DETAILED DESCRIPTION

[0028] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0029] In the description of the embodiments of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or detachably connected, or integrally connected; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0030] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0031] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0032] Figure 1 This is a flowchart of a method for preparing a selective light-absorbing material with a three-dimensional mesh structure, as provided in an embodiment of the present invention.

[0033] See Figure 1 This invention provides a method for preparing a selective light-absorbing material with a three-dimensional mesh structure, specifically including the following steps: Step S1: Irradiate the polymer template with heavy ions to obtain a polymer template containing a latent track structure.

[0034] Understandably, heavy ion irradiation of polymer templates is a key pretreatment step. The purpose is to induce controllable structural changes (such as molecular chain breakage, cross-linking, or latent track formation) within the polymer through the interaction between high-energy ions and polymer molecules. This provides a microstructural basis for subsequent steps such as UV etching, metal deposition, and template dissolution, ultimately achieving the precise construction of a three-dimensional mesh structure.

[0035] Wherein, the heavy ions as charged particles, when passing through the polymer, will deposit high-density energy along its trajectory to form a "track", causing the molecular chains in the track area to break sharply. These latent tracks will be selectively dissolved in subsequent ultraviolet etching, thereby forming a precursor structure of nanoscale to microscale channels or grid cells in the polymer template. And the heavy ion irradiation can introduce defects (such as vacancies, free radicals) on the surface or inside of the polymer, which will increase the absorption efficiency of the material to ultraviolet light or reduce the energy threshold required for photodecomposition, making the ultraviolet etching process more efficient and directional, such as anisotropic etching along the track direction, thereby precisely controlling the aperture, pitch and other parameters of the three-dimensional grid.

[0036] The material of the polymer template employed in the embodiments of the present application can be selected from, but not limited to, polyethylene terephthalate (PET) or polycarbonate (PC), etc. Polyethylene terephthalate (PET) has high strength and weather resistance, the molecular chain has a rigid aromatic structure, and the chains are tightly connected through ester bonds, which endows it with good creep resistance and tear resistance, and it is not easy to break due to repeated bending or stretching.

[0037] In some cases, the material of the polymer template can also be selected from polyimide, polymethyl methacrylate or polystyrene film.

[0038] The thickness of the polymer template is less than 30 µm, such as 15 µm, 6 µm or 5 µm, etc. If the polymer template is too thick, such as greater than 30 microns, the uniformity of the channels formed after ultraviolet etching of the track is reduced, and the subsequent electrochemical deposition may not be able to grow a uniform three-dimensional grid structure.

[0039] The heavy ions can be at least one of 86 Kr, 129 Xe, 183 Ta and 209 Bi. The irradiation fluence of the heavy ions is between 1×10 9 ions / cm 2 and 1×10 11 ions / cm 2 , preferably the irradiation fluence of the heavy ions is 1×10 10 ions / cm 2 .

[0040] The energy of the heavy ions is 2000 MeV to 2500 MeV, such as 2000 MeV, 2200 MeV, 2400 MeV or 2500 MeV, etc.

[0041] The angle between the irradiation direction of the heavy ions and the plane where the polymer template is located is greater than 0° and less than or equal to 90°, and preferably is 90°, 60° or 45°.

[0042] The number of times of heavy ion irradiation can be multiple, preferably 4 or 5 times, for example, 4 times at an angle of 45° or 4 times at an angle of 60°; or 4 times at an angle of 45°, followed by 1 time at an angle of 90°, or 4 times at an angle of 60°, followed by 1 time at an angle of 90°.

[0043] It should be noted that by performing heavy ion irradiation on the polymer template, a gradient structure of latent tracks, molecular chain breakage and chemical activation is constructed, so that during subsequent ultraviolet etching, the ion track area is preferentially etched (to form initial pores), and the unirradiated area remains relatively intact (as a support phase of the grid). Combined with electrochemical deposition of metal (to fill the pores) and template dissolution (to remove the polymer template), a three-dimensional selective light-absorbing material composed of a metal grid and a polymer void can be finally obtained.

[0044] Step S2: ultraviolet etching of the polymer template containing the latent track structure.

[0045] It can be understood that before ultraviolet etching, the polymer template containing the latent tracks needs to be pretreated to remove surface contaminants, optimize the activity of the latent tracks, and ensure the uniformity of the etching process.

[0046] The ultraviolet light source used in the ultraviolet etching can be, but is not limited to, a 365 nm high-pressure mercury lamp, and the power of the ultraviolet light source can be 5 mW·cm −2 to 100 mW·cm −2 , and the ultraviolet etching time is 10 min to 10 h. Specifically, the following steps are taken: The cleaned polymer template is fixed on a sample stage to ensure that the polymer template is flat and does not warp; the ultraviolet light source is turned on and preheated for 10 to 15 minutes until the power is stable; the etching program is started according to the set parameters (such as power, time, temperature), and the polymer template is placed in a position perpendicular to the direction of the ultraviolet light, and both sides of the polymer template are etched.

[0047] Step S3: electrochemical deposition of metal on the polymer template after ultraviolet etching to obtain a three-dimensional grid-polymer composite structure filled with metal nanowires.

[0048] It can be understood that the electrochemical deposition of metal on the polymer template after ultraviolet etching to prepare the metal nanowire filled three-dimensional grid-polymer composite structure is the core link of connecting the nanochannel template and the three-dimensional grid functional material. It forms a composite of metal grid and polymer template by electrochemical deposition of metal ions into the nanoscale channels of the polymer template, providing a key intermediate product for the subsequent selective light absorption material of the independent three-dimensional grid structure after dissolving the polymer template. The implementation process needs to combine the structural characteristics of the polymer template (such as channel size, depth) and the kinetics of electrochemical deposition, and realize the directional filling and continuous growth of metal nanowires by precise control of process parameters.

[0049] Since the polymer template itself is an insulator, it cannot be directly used as the cathode for electrochemical deposition. Therefore, a layer of gold with a thickness of 10 nm to 50 nm can be sprayed on one side of the polymer template to serve as an electrode.

[0050] Among them, the metal for electrochemical deposition is at least one of gold, silver, copper or platinum; the electrolyte is a salt solution containing corresponding metal ions; the deposition time is 1-180 minutes.

[0051] The metal deposition is carried out by applying a direct current voltage or a pulse voltage on both sides of the polymer template by an electrochemical workstation. Generally, a direct current voltage (0.5V to 2V) is used to deposit the substrate first, and then a pulse voltage (+1V to +2V, -0.2V) is used to deposit the three-dimensional grid structure.

[0052] Step S4: Dissolving the metal nanowire filled three-dimensional grid-polymer composite structure to obtain a selective light absorption material with a three-dimensional grid structure. The selective light absorption material with a three-dimensional grid structure is highly interconnected with billions of metal nanowires, and the structure porosity and nanowire feature size can be controlled.

[0053] It can be understood that dissolving the metal nanowire filled three-dimensional grid-polymer composite structure mainly removes the polymer template by a selective solvent to release an independent metal three-dimensional grid structure. This step eliminates the scattering and absorption of light by the polymer, activates the plasmonic resonance effect of the metal, and improves the mechanical and environmental adaptability of the material, ultimately realizing the breakthrough of the selective light absorption material in the core performance of high absorption in visible light and low emission in infrared light.

[0054] Dissolving the metal nanowire filled three-dimensional grid-polymer composite structure needs to be based on the chemical incompatibility of the polymer and the metal, and to select an organic solvent or etching liquid that can selectively dissolve the polymer without damaging the metal nanowires.

[0055] Take PET / Au composite structure as an example: PET is a polar polyester, which is easy to dissolve in polar organic solvents (such as acetone, DMF). Gold (Au) is an inert metal, which is insoluble in conventional organic solvents or dilute acid and alkali solutions (only soluble in aqua regia and other strong oxidizing acids, but it will destroy the metal grid). Therefore, acetone is the most preferred solvent (fast dissolution rate for PET, no corrosion for Au).

[0056] The organic solvent provided by the embodiment of the application can be specifically dichloromethane, dichloroethane, phenol and the like.

[0057] It should be noted that dissolving the three-dimensional grid-polymer composite structure filled with metal nanowires is a key turning point to realize the selective light absorption function. In the composite structure filled with metal nanowires, the polymer template wraps the metal grid, which will hinder the direct interaction of the metal with the external light. After dissolution, the metal grid is completely exposed to the environment, and the three-dimensional interconnected nanowire structure and the periodic pore distribution are fully exhibited, thereby activating the following optical properties: Localized surface plasmon resonance (LSPR): The periodic arrangement of metal nanowires (such as Au) matches the wavelength of visible light, which can excite strong LSPR effect in the visible light band, form localized enhanced electric field, and significantly improve the light absorption efficiency.

[0058] Multi-scale resonant cavity: The pores of the grid unit and the nanowire diameter form a multi-level size structure, which can simultaneously regulate the resonance modes of different wave bands (such as blue light and green light), and expand the width of the absorption wave band.

[0059] Infrared low emissivity: For infrared light, the characteristic size of the metal nanostructure is much smaller than the wavelength, which approximates the structure surface to the bulk metal surface, showing strong infrared reflection, i.e. low infrared absorption rate.

[0060] To ensure the success of the dissolution step, the quality of the final material can be verified by the following means: using a scanning electron microscope (SEM) to observe the three-dimensional structure of the metal grid (such as pore diameter, nanowire diameter, connectivity). The spectral response of the material is detected by an ultraviolet-visible-infrared spectrophotometer (UV-Vis-IR), and it is verified that the average absorption rate in the visible light band is greater than 98%.

[0061] It should be noted that in the embodiments of the present application, the polymer template is a sacrificial mold. The role of the polymer template is to provide a three-dimensional spatial confinement framework for the growth of metal nanowires. The polymer template is eventually completely removed, and the three-dimensional grid structure formed by the metal nanowires is the target product. The purpose of ultraviolet etching the polymer template is to first construct the cavity structure of the three-dimensional grid (similar to the cavity of the mold), and then fill the metal into the cavities through electrochemical deposition. Finally, the metal is released by dissolving the template to form an independent three-dimensional grid. The essence is to indirectly construct the specific structure of the target material (metal) by using the spatial constraint of the polymer template.

[0062] The preparation of traditional three-dimensional metal structures (such as mechanical processing, laser engraving or ordinary photolithography) usually faces problems such as difficulty in processing complex structures and difficulty in controlling nanoscale precision. The preparation method of the selective light absorption material with a three-dimensional grid structure provided by the embodiments of the present application uses the three-dimensional spatial confinement effect of the polymer template to constrain the growth of metal nanowires in the cavities of the template by means of polymer template, metal deposition and template removal, thereby indirectly realizing the precise construction of complex three-dimensional metal grid. This preparation process breaks through the limitations of direct metal processing and provides a new path for the preparation of high-precision and complex three-dimensional metal structures.

[0063] The following illustrates the preparation method of the selective light absorption material with a three-dimensional grid structure: Figure 2 is a scanning electron microscope (SEM) image of the selective light absorption material with a three-dimensional grid structure prepared in Embodiment 1 of the present application; wherein (a) is an overall morphology image of the material at a magnification of 10 microns, which is used to show the macroscopic distribution characteristics of the three-dimensional grid structure; (b) is a local detail image of the material at a magnification of 1 micron, which is used to present the microscopic morphology and size characteristics of the grid unit. Figure 3 is a transmission electron microscope (TEM) image of the selective light absorption material with a three-dimensional grid structure prepared in Embodiment 1 of the present application, which is used to directly show the microscopic characteristics of the three-dimensional grid structure inside the material (such as the connectivity of the grid unit, the distribution of the pores or the interface morphology of the metal deposition phase and the polymer template, etc.). Figure 4 is an optical photograph of the selective light absorption material with a three-dimensional grid structure prepared in Embodiment 1 of the present application.

[0064] Embodiment 1: The polycarbonate (PC) with a thickness of 6 µm was irradiated by the TR5 irradiation terminal of the heavy ion research facility (HIRFL). The irradiation ion was Xe, the energy of the heavy ion was 2500 MeV, the irradiation fluence was 2×10 10 ions / cm 2 The angle between the irradiation direction (ion beam) of the heavy ion and the plane where the polymer template was located was 45°, and the irradiation was performed in four directions.

[0065] The PC polymer template after heavy ion irradiation is subjected to ultraviolet etching, and the power of the ultraviolet light is 5-100 mW / cm 2 Each side of the PC polymer template is etched for 4 hours.

[0066] A layer of gold with a thickness of about 20 nm is sputtered on one side of the etched PC polymer template, and the side of the gold-sprayed PC polymer template is subjected to electrochemical deposition of gold substrate, with a deposition voltage of 1 V and a deposition time of 6 hours. On the other side of the PC polymer template, pulse electrodeposition is performed with a deposition voltage of 1.1 V for 15 seconds, -0.2 V for 5 seconds, and a deposition time of 15 minutes.

[0067] The composition of the gold electrolyte is selected as 75 g / l of Na3Au(SO3)2. The sample after electrochemical deposition is placed in dichloromethane to dissolve the PC polymer template, and the dissolution time is greater than 12 hours. It is worth noting that due to the small size of the nanowires, local collapse may occur due to stress during the dissolution of the PC polymer template. Finally, a selective light-absorbing material with a three-dimensional grid structure with a feature size of about 10 nm is obtained.

[0068] The scanning electron microscope (SEM) image of the selective light-absorbing material with a three-dimensional grid structure is shown in Figure 2 , wherein (a) is the overall morphology of the material at a magnification of 10 microns, showing the macroscopic distribution characteristics of the three-dimensional grid structure; (b) is the local detail view of the material at a magnification of 1 micron, showing the microscopic morphology and size characteristics of the grid unit.

[0069] The transmission electron microscope (TEM) image of the selective light-absorbing material with a three-dimensional grid structure is shown in Figure 3 , which directly shows the microscopic characteristics of the three-dimensional grid structure inside the material (such as the connectivity of the grid unit, the distribution of the pores, or the interface morphology of the metal deposition phase and the polymer template, etc.).

[0070] The optical photograph of the selective light-absorbing material with a three-dimensional grid structure is shown in Figure 4 , which appears black due to its strong absorption of sunlight.

[0071] Figure 5 is the absorption spectrum of the selective light-absorbing material with a three-dimensional grid structure prepared in Example 1 in the visible to mid-infrared waveband. Specifically, the absorption spectrum of the radiation-cooled nuclear pore membrane prepared in Example 1 in the mid-infrared waveband is used, and the average absorption rate in the visible light waveband of 300 nm-800 nm is greater than 98%, and the absorption rate in the near-infrared waveband of 5 μm-20 μm is less than 30%.

[0072] Due to the strong coupling between the grid pores and the nanowire diameter and the visible light wavelength, a significant localized surface plasmon resonance (LSPR) effect is excited, forming a dense local enhanced electric field, which greatly improves the light absorption efficiency, so that the visible light absorption rate is high, that is, the average absorption rate of 300 nm-800 nm is greater than 98%.

[0073] The continuous conductivity of the metal grid dominates the free electron gas oscillation in the infrared band, reflecting the infrared photons; at the same time, the pore size of less than 10 nm is much smaller than the infrared wavelength (5-20 μm), avoiding the scattering loss of infrared light, and finally realizing the infrared low absorption characteristic, so that the near-infrared absorption rate is low, and the absorption rate of 5-20 μm is less than 30%.

[0074] Embodiment 2 The TR5 irradiation terminal of the heavy ion research device (HIRFL) was used to irradiate a polycarbonate (PC) with a thickness of 6 μm, the irradiation ion was Xe, the ion energy was 2500 MeV, and the irradiation fluence was 1×10 10 ions / cm 2 The angle between the irradiation direction (ion beam) of the heavy ion and the plane of the polymer template was 45°, and irradiation was performed in 4 directions.

[0075] The irradiated PC polymer template was subjected to ultraviolet etching, the ultraviolet light power was 5-100 mW / cm 2 , and each side was etched for 2h. A layer of gold with a thickness of about 20 nm was sputtered on one side of the etched PC polymer template, and gold substrate was electrochemically deposited on the side of the PC polymer template after gold spraying, the deposition voltage was 1V direct current voltage, and the deposition time was 6h; gold was electrochemically deposited on the other side of the PC polymer template, and the deposition voltage was 1.1V, 15s, -0.2V, 5s pulse electrodeposition, and the deposition time was 15min.

[0076] Among them, the gold electrolyte composition can be 75g / l of Na3Au(SO3)2. The sample after electrochemical deposition was placed in dichloromethane to dissolve the PC polymer template, and the dissolution time was greater than 12h, and finally a selective light absorption material with a three-dimensional grid structure with a feature size of about 8 nm was obtained, and the SEM image is shown in Figure 6 Due to the low density of the nanowires of the sample, the grid structure collapses. Due to the limitation of the SEM resolution, the sample was characterized by TEM, as shown in Figure 7 .

[0077] It can be understood that the embodiment of the present application realizes the whole process of synergistic technology of latent track induction by heavy ion irradiation, directional etching by ultraviolet etching, electrochemical deposition and template dissolution, couples the template preparation and metal deposition in the prior art, and does not need additional post-processing steps (such as cleaning and repairing). The process simplification directly reduces the process steps (from 4-5 steps in the traditional process to 2-3 steps), significantly improves the preparation efficiency, and reduces the risk of structure damage (such as metal layer falling off and channel blockage) caused by multi-step operation.

[0078] The embodiment of the present application adopts a polymer film (such as PET) as a substrate, which has high flexibility and low-cost roll-to-roll processing characteristics, and is suitable for large-area continuous preparation requirements. At the same time, the heavy ion irradiation and ultraviolet etching process have strong compatibility with polymer types (such as PET, PI, PC, etc.), and the metal deposition step can be adapted to gold, silver, copper and other metals by adjusting the electrolyte formula, which breaks through the strict limitation of the substrate material in the traditional technology (such as only suitable for radiation-resistant polymers). Large-area preparation capability reduces the cost per unit area, and the material types can be expanded to different application scenarios (such as aerospace, optoelectronics and stealth).

[0079] The embodiment of the present application realizes that the feature size (pore, line width) of the three-dimensional grid structure is controllable to be less than 10 nm through the latent track guiding mechanism induced by heavy ion irradiation, combined with the directional dissolution of ultraviolet etching and the directional growth of nanowires by electrochemical deposition. This ultra-fine structure directly determines the breakthrough of optical performance: The grid pore and nanowire diameter form a strong coupling with the visible light wavelength, excite a significant localized surface plasmon resonance (LSPR) effect, form a dense local enhanced electric field, and greatly improve the light absorption efficiency, so that the visible light absorption rate is high, that is, the average absorption rate of 300 nm-800 nm is greater than 98%.

[0080] The continuous conductivity of the metal grid dominates the free electron gas oscillation in the infrared waveband, and reflects the infrared photons. At the same time, the pore size of less than 10 nm is much smaller than the infrared wavelength (5-20 μm), which avoids the scattering loss of infrared light, and finally realizes the infrared low absorption characteristic, so that the near-infrared absorption rate is low, and the absorption rate of 5-20 μm is less than 30%.

[0081] Therefore, the embodiment of the present application solves the core defects of the prior art in efficiency, cost and precision through the synergistic innovation of process simplification, material universality expansion and feature size precise control, finally endows the selective light absorption material with excellent performance of high visible light absorption and low near-infrared emission, and has significant advantages in large-scale preparation and application adaptability.

[0082] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for producing a selective light-absorbing material having a three-dimensional network structure, characterized by, The method comprises the following steps: subjecting a polymer template to multiple heavy ion irradiation at different angles to obtain a polymer template containing a cross-linked latent track structure; subjecting the polymer template containing the latent track structure to ultraviolet etching; subjecting the polymer template after ultraviolet etching to electrochemical deposition of metal to obtain a metal nanowire-filled three-dimensional grid-polymer composite structure; subjecting the metal nanowire-filled three-dimensional grid-polymer composite structure to dissolution to obtain a selective light-absorbing material with a three-dimensional grid structure.

2. The method of claim 1, wherein the method further comprises the step of: The polymer template comprises polyethylene terephthalate or polycarbonate, and the thickness of the polymer template is less than 30 µm. ​ 3. The method of claim 1, wherein the method further comprises the step of: The power of the UV light source used for the UV etching is 5 mW-cm −2 up to 100 mW-cm −2 . ​ 4. The method of claim 3, wherein the method further comprises the step of: The ultraviolet etching time is 10 min to 10 h. ​ 5. The method of claim 1, wherein the method further comprises the step of: The electrochemical deposition of metal on the polymer template after ultraviolet etching to obtain a metal nanowire-filled three-dimensional grid-polymer composite structure comprises: ​ spraying gold with a thickness of 10 nm to 50 nm on one side of the polymer template as an electrode; depositing a substrate on both sides of the polymer template using a direct current voltage, and then depositing a three-dimensional grid structure using a pulse voltage.

6. A selective light absorbing material having a three-dimensional network structure, which is produced by the production method according to any one of claims 1 to 5, characterized in that, The three-dimensional grid structure of the material is composed of a metal deposition phase and a void after etching of the polymer template, and has selective absorption characteristics for specific wavelengths of light.

7. The selectively light-absorbing material having a three-dimensional mesh structure according to claim 6, wherein, In the wavelength range of 300 nm-800 nm, the average absorption rate of the selective light-absorbing material is greater than 98%.

8. The selective light absorbing material having a three-dimensional mesh structure according to claim 7, wherein, In the near-infrared wavelength range of 5 µm-20 µm, the average absorption rate of the selective light-absorbing material is less than 30%.

9. The selective light absorbing material having a three-dimensional mesh structure according to any one of claims 6 to 8, characterized in that, The characteristic size of the selective light-absorbing material is less than or equal to 10 nm.

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