LED display screen based on nano coating technology and preparation method thereof

Abstract

The invention belongs to the technical field of LED display screens, and particularly relates to an LED display screen based on a nano coating technology and a preparation method of the LED display screen. Compared with the prior art, according to the LED display screen based on the nanometer coating technology, the transmittance and reflectivity of the LED display screen in different wave bands are adjusted through alternate coating of the low-refractive-index coatings and the high-refractive-index coatings, so that spectrum selective regulation and control are achieved, meanwhile, the reflection effect is improved through the surface prismoid-shaped microarray structure, the radiation surface area is increased, and the light transmittance of the LED display screen is improved. The heat dissipation performance and the optical requirement are balanced, so that outdoor LED display product cooling is achieved, and the heat dissipation device is particularly suitable for heat dissipation of an LED screen in an outdoor strong solar radiation area.

Description

Technical Field

[0001] This invention belongs to the field of LED display technology, and particularly relates to an LED display based on nano-coating technology and its preparation method. Background Technology

[0002] LED displays have been widely used in outdoor commercial displays due to their advantages such as wide viewing angles, high brightness, high color saturation, and customizability. However, due to long-term outdoor operation, in addition to their own heat generation, the screen is also exposed to solar radiation heat (approximately 45% of solar heat comes from the 0.3~0.8 μm wavelength band, and approximately 52% from the 0.8~2.5 μm wavelength band). Under the combined effect of their own power consumption and solar radiation, the surface of outdoor displays typically reaches high temperatures (>80℃), leading to color shift and lifespan reduction.

[0003] Traditional heat dissipation solutions, such as adding heat sinks to the display screen or installing fans within the module, increase the product's size and weight. Other integrated heat dissipation solutions, such as adding fans or air conditioners to the screen and installation space, not only increase cost and noise but are also limited by the actual installation conditions of the project. In some projects, heat dissipation equipment cannot be installed, significantly compromising screen display quality and operational reliability. Therefore, there is an urgent need for a coating material that does not affect display quality while possessing excellent heat dissipation performance to address the high-temperature problem of outdoor displays. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide an LED display screen with good cooling effect based on nano-coating technology and its preparation method.

[0005] This invention provides an LED display screen based on nano-coating technology, comprising:

[0006] LED display screen body;

[0007] The light-emitting surface of the LED display screen body is provided with a coating layer;

[0008] The surface of the coating layer away from the LED display body is provided with a frustum-shaped microarray structure.

[0009] The coating layer includes alternating low-refractive-index coatings and high-refractive-index coatings; one alternating layer of the low-refractive-index coating and one alternating layer of the high-refractive-index coating constitutes one cycle; in each cycle, the high-refractive-index coating is disposed on the surface of the low-refractive-index coating that is away from the LED display body;

[0010] The low-refractive-index coating comprises low-refractive-index nanoparticles; the refractive index of the low-refractive-index nanoparticles is less than or equal to 2; the high-refractive-index coating comprises high-refractive-index nanoparticles; the refractive index of the high-refractive-index nanoparticles is greater than 2.

[0011] Preferably, the side length of the surface of a single frustum away from the LED display body of the frustum-shaped microarray structure is 10~30 μm; the side length of the bottom surface of a single frustum in contact with the LED display body is 30~70 μm.

[0012] The height of the frustum-shaped microarray structure is 10~50 μm;

[0013] The spacing between adjacent individual frustums in the frustum-shaped microarray structure is 30~70 μm;

[0014] The sidewall inclination angle of a single frustum in the frustum-shaped microarray structure is 60°~80°.

[0015] Preferably, the sidewall of each frustum of the frustum-shaped microarray structure is provided with a groove parallel to the LED display body; the depth of the groove is 1~8 μm;

[0016] The width of the groove is 1~10 μm.

[0017] Preferably, the thickness of the low-refractive-index coating in each cycle is independently 100~300 nm;

[0018] The thickness of the high-refractive-index coating in each cycle is independently 100~300 nm;

[0019] The number of alternating cycles is 2 to 6.

[0020] Preferably, the low refractive index coating comprises a first matrix resin, ZrO2 particles, a first black filler, and low refractive index nanoparticles;

[0021] The low-refractive-index nanoparticles have a particle size of 10~100 nm;

[0022] The mass of the low-refractive-index nanoparticles is 1% to 20% of the mass of the first matrix resin;

[0023] The low-refractive-index nanoparticles are selected from one or more of SiO2 particles, Si3N4 and Al2O3 particles;

[0024] The high refractive index coating comprises a second matrix resin, ZrO2 particles, a second black filler, and high refractive index nanoparticles.

[0025] The high-refractive-index nanoparticles have a particle size of 10~100 nm;

[0026] The mass of the high refractive index nanoparticles is 1% to 10% of the mass of the second matrix resin;

[0027] The high refractive index nanoparticles are selected from one or more of TiO2 particles, Si3N4 particles and ZnS particles.

[0028] Preferably, the mass of ZrO2 particles in the low-refractive-index coating is 0.1% to 2% of the mass of the first matrix resin;

[0029] The mass of the first black filler is 0.1% to 2% of the mass of the first matrix resin;

[0030] The mass of ZrO2 particles in the high refractive index coating is 0.1% to 2% of the mass of the second matrix resin;

[0031] The mass of the second black filler is 0.1% to 2% of the mass of the second matrix resin;

[0032] The frustum-shaped microarray structure includes a third matrix resin, ZrO2 particles, and a third black filler.

[0033] The mass of ZrO2 particles in the frustum-shaped microarray structure is 0.1% to 2% of the mass of the third matrix resin;

[0034] The mass of the third black filler is 0.1% to 2% of the mass of the third matrix resin.

[0035] Preferably, the first matrix resin, the second matrix resin, and the third matrix resin are each independently selected from one or more of epoxy resin, silicone resin, acrylic resin, and polyester resin;

[0036] The particle size of ZrO2 particles in the low-refractive-index coating, the high-refractive-index coating, and the frustum-shaped microarray structure is independently 10~100 nm.

[0037] The first black filler, the second black filler, and the third black filler are each independently selected from one or more of carbon black, iron oxide, and carbon nanotubes;

[0038] The particle sizes of the first, second, and third black fillers are each independently 10~100 nm.

[0039] Preferably, a thermally conductive interface layer is further provided between the LED display body and the coating layer; the thermally conductive interface layer includes a fourth matrix resin and aluminum nitride; the thickness of the thermally conductive interface layer is 10~100 μm.

[0040] Preferably, a silica microporous array layer is further provided between the LED display body and the thermal interface layer; the silica microporous array layer is formed by silica nanoparticles; the particle size of the silica nanoparticles is 10~100nm.

[0041] The present invention also provides a method for manufacturing the above-mentioned LED display screen based on nano-coating technology, comprising the following steps:

[0042] S1) Provides the LED display screen body;

[0043] S2) Alternately deposit low-refractive-index coatings and high-refractive-index coatings on the light-emitting surface of the LED display body to form a coating layer;

[0044] S3) Using photoresist process, exposure and development are performed to form a photoresist layer with a frustum-shaped microarray structure model. A frustum-shaped microarray structure is prepared in the photoresist layer with the frustum-shaped microarray structure model to obtain an LED display screen based on nano-coating technology.

[0045] Compared with existing technologies, the LED display screen based on nano-coating technology provided by this invention adjusts its transmittance and reflectance in different wavelength bands through alternating coatings of low-refractive-index and high-refractive-index coatings, thereby achieving spectral selectivity control. At the same time, the surface frustum-shaped microarray structure increases the reflection effect, increases the radiation surface area, and balances heat dissipation performance and optical requirements, thereby achieving cooling of outdoor LED display products, which is particularly suitable for heat dissipation of LED screens in areas with strong outdoor solar radiation.

[0046] Experimental results show that the LED display screen based on nano-coating technology provided by the present invention has high transmittance in 0.3~0.8 μm, high reflectivity in 0.8~2.5 μm, and high emissivity in 8~13 μm. It can reduce the lamp surface temperature by 4℃~9℃, and the cooling effect increases with the increase of solar irradiance. Attached Figure Description

[0047] Figure 1 A solar spectrum diagram;

[0048] Figure 2 A schematic diagram of the structure of an LED display screen based on nano-coating technology provided by the present invention;

[0049] Figure 3 A top view schematic diagram of an LED display screen based on nano-coating technology provided by the present invention;

[0050] Figure 4 A schematic diagram of a frustum-shaped microarray structure with grooves on the sidewalls;

[0051] Figure 5This is a schematic diagram of the process for preparing an LED display screen in Embodiment 1 of the present invention. Detailed Implementation

[0052] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0053] The atmosphere, the space between the Earth's surface and space, is a semi-transparent medium composed of numerous gases. From a radiation perspective, due to its low transmittance, the atmosphere weakens thermal radiation from the Earth's surface to space in most wavelength ranges. However, in the wavelength range of 8–13 μm (the atmospheric window), the atmosphere has high transparency for thermal radiation. Since the atmospheric window coincides with the peak wavelength of thermal radiation from Earth's objects at typical ambient temperatures, any upward-facing object with high emissivity in this wavelength range can radiate heat into space, such as… Figure 1 As shown. The transmittance of atmospheric windows is affected by many factors, such as geographical location, cloud cover, and humidity conditions. Generally, the clearer and drier the sky, the higher the transmittance of atmospheric windows. Radiative cooling materials are designed to have high reflectivity in the solar spectrum and high emissivity in the atmospheric window band, achieving powerless cooling and thus achieving environmental protection and energy conservation.

[0054] Based on this, the present invention provides an LED display screen based on nano-coating technology, comprising: an LED display screen body; a coating layer disposed on the light-emitting surface of the LED display screen body; a frustum-shaped micro-array structure disposed on the surface of the coating layer away from the LED display screen body; the coating layer comprising alternating low-refractive-index coating and high-refractive-index coating; one alternating layer of the low-refractive-index coating and one alternating layer of the high-refractive-index coating constitutes one cycle; in each cycle, the high-refractive-index coating is disposed on the surface of the low-refractive-index coating away from the LED display screen body; the low-refractive-index coating comprises low-refractive-index nanoparticles; the refractive index of the low-refractive-index nanoparticles is less than or equal to 2; the high-refractive-index coating comprises high-refractive-index nanoparticles; the refractive index of the high-refractive-index nanoparticles is greater than 2.

[0055] See Figure 2 , Figure 2 This is a schematic diagram of the structure of an LED display screen based on nano-coating technology provided by the present invention, wherein 1 is the LED display screen body, 2 is the coating layer, 2-1 is a low refractive index coating, 2-8 is a high refractive index coating, and 3 is a frustum-shaped microarray structure.

[0056] See Figure 3 , Figure 3This is a top view schematic diagram of an LED display screen based on nano-coating technology provided by the present invention.

[0057] In a specific embodiment of the present invention, to further improve the heat dissipation and thermal conductivity continuity of the LED display screen, a thermally conductive interface layer is further provided between the LED display screen body and the coating layer; the thickness of the thermally conductive interface layer is preferably 10~100 μm; optionally, the thickness of the thermally conductive interface layer is 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm or any two of the above values; the thermally conductive interface layer comprises a fourth matrix resin and aluminum nitride; the fourth matrix resin is preferably one or more of epoxy resin, silicone resin, acrylic resin and polyester resin; the adhesion between the coating and the matrix, in the present invention, the fourth matrix resin is preferably epoxy resin, including but not limited to two-component F-type epoxy resin and / or bisphenol A type epoxy resin; the molecular weight of the epoxy resin is preferably 300~700. The molecular weight of the epoxy resin is 300 g / mol, 350 g / mol, 400 g / mol, 450 g / mol, 500 g / mol, 550 g / mol, 600 g / mol, 650 g / mol, 700 g / mol, or any two of the above values. The epoxy equivalent of the epoxy resin is preferably 180-250 g / eq. A molecular weight below this value may result in excessively high crosslinking density and increased brittleness, while a molecular weight above this value may reduce heat resistance and chemical resistance. Optionally, the epoxy equivalent of the epoxy resin is 180 g / eq, 190 g / eq, 200 g / eq, 210 g / eq, 220 g / eq, 230 g / eq, 240 g / eq, 250 g / eq, or 180 g / eq. g / eq or any two of the above values; the particle size of the aluminum nitride is preferably 10~100 nm; optionally, the particle size of the aluminum nitride is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm or any two of the above values; the mass of the aluminum nitride is preferably 1%~20% of the mass of the fourth matrix resin; optionally, the mass of the aluminum nitride is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% of the mass of the fourth matrix resin or any two of the above values.

[0058] In one specific embodiment of the present invention, the fourth matrix resin is preferably derived from the epoxy two-component reactive ink of the YMD-HCP series screen printing design.

[0059] In a specific embodiment of the present invention, a silica microporous array layer is preferably further provided between the LED display body and the coating layer or between the LED display body and the thermally conductive interface layer; the silica microporous array layer can enhance the interfacial mechanical bonding force; the silica microporous array layer is formed of silica nanoparticles; the content of silica nanoparticles in the silica microporous array layer is preferably 0.1~1 mg / cm³. 2 Optionally, the content of silica nanoparticles in the silica microporous array layer is preferably 0.1 mg / cm³. 2 0.2 mg / cm 2 0.3 mg / cm 2 0.4 mg / cm 2 0.5 mg / cm 2 0.6 mg / cm 2 0.7 mg / cm 2 0.8 mg / cm 2 0.9 mg / cm 2 1 mg / cm 2 Or the range between any two of the above values; the particle size of the silica nanoparticles is preferably 10~100 nm; the particle size of the silica nanoparticles is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm or the range between any two of the above values.

[0060] Since the optical properties of a single homogeneous material are determined by its intrinsic complex refractive index, its spectral reflectance / emissivity curve is usually fixed and relatively simple. However, it is difficult to find a single material that simultaneously exhibits high transmittance in the visible light band (0.3–0.8 μm), high reflectance in the near-infrared band (0.8–2.5 μm), and high emissivity in a specific mid-infrared band (8–13 μm). Therefore, this invention employs a multilayer stacked structure to construct a spectrally selective coating layer. Multilayer stacking typically consists of alternating layers of two or more materials with different refractive indices and specific thicknesses. When light shines on this multilayer structure, reflection and transmission occur at the interfaces of each layer. There is an optical path difference (determined by layer thickness and refractive index) between the light waves reflected from different interfaces. When these reflected light waves meet at the front surface of the material, constructive or destructive interference occurs.

[0061] In one specific embodiment of the present invention, the coating layer includes alternating low-refractive-index coatings and high-refractive-index coatings; one alternating layer of the low-refractive-index coating and one alternating layer of the high-refractive-index coating constitutes one cycle; the thickness of the low-refractive-index coating in each cycle can be the same or different, without special limitations. Specifically, the thickness of the low-refractive-index coating in each cycle is preferably 100~300 nm; optionally, the thickness of the low-refractive-index coating in each cycle is 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, or a range between any two of the above values; the thickness of the high-refractive-index coating in each cycle can be the same or different, without special limitations. Specifically, the thickness of the high-refractive-index coating in each cycle is preferably 100~300 nm; optionally, the thickness of the high-refractive-index coating in each cycle is 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 19 ... nm, 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, or any two of the above values; by carefully designing the thickness of each layer (usually designed to be a quarter wavelength or half wavelength thickness) and refractive index, most of the reflected light can undergo constructive interference in the solar spectrum band (0.3~2.5 µm). This means that the light waves reflected back from different interfaces have the same phase, and the amplitude increases after superposition, thereby greatly enhancing the overall reflectivity of the material surface to sunlight.

[0062] In one specific embodiment of the present invention, the thickness of the low refractive index coating in each period is preferably 180~220 nm (quarter wavelength); optionally, the thickness of the low refractive index coating in each period is independently 180 nm, 190 nm, 200 nm, 210 nm, 220 nm or any two of the above values.

[0063] In each cycle of the coating layer, a high-refractive-index coating is disposed on the surface of the low-refractive-index coating away from the LED display body; the low-refractive-index coating at the bottom of each cycle contains a material that is transparent (low-absorption) in the solar spectrum and has a low refractive index, which acts as an emitting layer and can efficiently absorb infrared radiation transmitted through the atmospheric window of the top multi-layer structure; the refractive index of the low-refractive-index nanoparticles is less than or equal to 2; specifically, the refractive index of the low-refractive-index nanoparticles is 1.4~2, more specifically 1.4~1.8; optionally, the refractive index of the low-refractive-index nanoparticles is 1.4, 1.45, 1.5, 1.6, 1.7, 1.8 or any two of the above values; in a specific embodiment provided by the present invention, the low-refractive-index nanoparticles are preferably one or more of SiO2 particles, Si3N4 and Al2O3 particles; the particle size of the low-refractive-index nanoparticles is preferably 10~100 nm; optionally, the particle size of the low-refractive-index nanoparticles is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm. nm, 90 nm, 100 nm, or any range between two of the above values.

[0064] In one specific embodiment of the present invention, the low refractive index nanoparticles are preferably SiO2 particles; the particle size of the low refractive index nanoparticles is preferably 50 nm; at this time, the emissivity of the low refractive index nanoparticles can reach 94%.

[0065] The composition of the low-refractive-index coating in each cycle can be the same or different, without any special restrictions. In a specific embodiment provided by the present invention, the low-refractive-index coating includes a first matrix resin, ZrO2 particles, a first black filler, and low-refractive-index nanoparticles. The first matrix resin is preferably one or more of epoxy resin, silicone resin, acrylic resin, and polyester resin. To meet the requirements of high light transmittance and high temperature resistance of the LED display surface, the first matrix resin is preferably polymethyl methacrylate, more preferably polymethyl methacrylate with a light transmittance greater than or equal to 92%. The particle size of the ZrO2 particles is preferably 10~100 nm; optionally, the particle size of the ZrO2 particles is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm. The ZrO2 particles are preferably 0.1% to 2% of the mass of the first matrix resin; optionally, the ZrO2 particles are 0.1%, 0.5%, 1%, 1.5%, 2% of the mass of the first matrix resin, or any two of the above values; the first black filler can be any black filler known to those skilled in the art, and there are no special limitations, including but not limited to one or more of carbon black, iron oxide, and carbon nanotubes; the particle size of the first black filler is preferably 10 to 100 nm; optionally, the particle size of the first black filler is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm. nm or any two of the above values; the mass of the first black filler is preferably 0.1% to 2% of the mass of the first matrix resin; optionally, the mass of the first black filler is 0.1%, 0.5%, 1%, 1.5%, 2% of the mass of the first matrix resin or any two of the above values; the mass of the low refractive index nanoparticles is preferably 1% to 20% of the mass of the first matrix resin; optionally, the mass of the low refractive index nanoparticles is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% of the mass of the first matrix resin or any two of the above values.

[0066] The high refractive index layer is located at the top of each cycle. It contains a material that is transparent to the solar spectrum (low absorption) and has a high refractive index, which can reflect infrared radiation. At the same time, in order to improve the overall transmittance of the LED display, the thickness of the high refractive index coating that is far away from the LED display body can be appropriately reduced. In this invention, the refractive index of the high-refractive-index nanoparticles is greater than 2, specifically, the refractive index of the high-refractive-index nanoparticles is 2.1~2.7; optionally, the refractive index of the high-refractive-index nanoparticles is 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7 or any two of the above values; in a specific embodiment provided by this invention, the high-refractive-index nanoparticles are preferably one or more of TiO2 particles, Si3N4 particles and ZnS particles; the particle size of the high-refractive-index nanoparticles is preferably 10~100 nm; optionally, the particle size of the high-refractive-index nanoparticles is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm or any two of the above values.

[0067] In one specific embodiment of the present invention, the high refractive index nanoparticles are preferably TiO2 particles; the particle size of the high refractive index nanoparticles is preferably 50 nm; at this time, the solar reflectivity of the high refractive index nanoparticles can reach 95%.

[0068] The composition of the high-refractive-index coating in each cycle can be the same or different, without any special restrictions. In a specific embodiment provided by the present invention, the high-refractive-index coating includes a second matrix resin, ZrO2 particles, a second black filler, and high-refractive-index nanoparticles. The second matrix resin is preferably one or more of epoxy resin, silicone resin, acrylic resin, and polyester resin. To meet the requirements of high light transmittance and high temperature resistance of the LED display surface, the second matrix resin is preferably polymethyl methacrylate, more preferably polymethyl methacrylate with a light transmittance greater than or equal to 92%. The particle size of the ZrO2 particles is preferably 10~100 nm; optionally, the particle size of the ZrO2 particles is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm. The ZrO2 particles are preferably 0.1% to 2% of the mass of the second matrix resin; optionally, the ZrO2 particles are 0.1%, 0.5%, 1%, 1.5%, 2% of the mass of the second matrix resin, or any two of the above values; the second black filler can be any black filler known to those skilled in the art, and there are no special limitations, including but not limited to one or more of carbon black, iron oxide, and carbon nanotubes; the particle size of the second black filler is preferably 10 to 100 nm; optionally, the particle size of the second black filler is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm. nm or any two of the above values; the mass of the second black filler is preferably 0.1% to 2% of the mass of the second matrix resin; optionally, the mass of the second black filler is 0.1%, 0.5%, 1%, 1.5%, 2% of the mass of the second matrix resin or any two of the above values; the mass of the high refractive index nanoparticles is preferably 1% to 10% of the mass of the second matrix resin; optionally, the mass of the high refractive index nanoparticles is 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10% of the mass of the second matrix resin or any two of the above values.

[0069] In the infrared atmospheric window band (8~13 µm), the design goal of the multilayer structure of the coating layer is to cause destructive interference of reflected light, or at least not to enhance reflection. This means that most of the incident infrared radiation can pass through the top multilayer reflective structure, thereby achieving high emissivity. In a specific embodiment provided by the present invention, the number of alternating periods in the coating layer is preferably 2~6; optionally, the number of alternating periods in the coating layer is 2, 3, 4, 5 or 6.

[0070] The more layers in the coating, the stronger the interference effect and the more precise and steeper the spectral modulation capability. However, too many layers increase cost and process complexity. The greater the difference in refractive index between adjacent layers, the higher the reflectivity of the single-layer interface, the fewer layers are needed to achieve the same reflectivity, and the stronger the interference effect. Therefore, in a specific embodiment provided by this invention, the number of alternating periods in the coating is 4, that is, the total number of low-refractive-index coatings and high-refractive-index coatings in the coating is 8.

[0071] In this invention, a frustum-shaped microarray structure is disposed on the surface of the coating layer away from the LED display body; in a specific embodiment provided by this invention, the frustum-shaped microarray structure is preferably a quadrangular frustum-shaped microarray structure; the cross-section of a single frustum of the frustum-shaped microarray structure perpendicular to the LED display body is trapezoidal. The inclined surface of the trapezoid increases the number of reflections, greatly increasing the probability of sunlight being reflected back into the sky. This helps to improve the reflectivity of the material within the solar spectrum.

[0072] In one specific embodiment of the present invention, the side length of the surface of a single frustum of the frustum-shaped microarray structure that is furthest from the LED display body is preferably 10~30 μm; optionally, the side length of the surface of a single frustum of the frustum-shaped microarray structure that is furthest from the LED display body is 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm or any two of the above values.

[0073] In one specific embodiment of the present invention, the bottom side length of a single frustum contacting the LED display body is preferably 30~70 μm; optionally, the bottom side length of a single frustum contacting the LED display body is 30 μm, 32 μm, 34 μm, 36 μm, 38 μm, 40 μm, 42 μm, 44 μm, 46 μm, 48 μm, 50 μm, 52 μm, 54 μm, 56 μm, 58 μm, 60 μm, 62 μm, 64 μm, 66 μm, 68 μm, 70 μm or any two of the above values.

[0074] In one specific embodiment of the present invention, the height of the frustum-shaped microarray structure is preferably 10~50 μm; optionally, the height of the frustum-shaped microarray structure is 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, 32 μm, 34 μm, 36 μm, 38 μm, 40 μm, 42 μm, 44 μm, 46 μm, 48 μm, 50 μm or any two of the above values.

[0075] In one specific embodiment of the present invention, the spacing between adjacent individual frustums of the frustum-shaped microarray structure is preferably 30~70 μm; optionally, the spacing between adjacent individual frustums of the frustum-shaped microarray structure is 30 μm, 32 μm, 34 μm, 36 μm, 38 μm, 40 μm, 42 μm, 44 μm, 46 μm, 48 μm, 50 μm, 52 μm, 54 μm, 56 μm, 58 μm, 60 μm, 62 μm, 64 μm, 66 μm, 68 μm, 70 μm or any two of the above values.

[0076] In one specific embodiment of the present invention, the sidewall inclination angle of a single frustum of the frustum-shaped microarray structure is preferably 60°~80°; optionally, the sidewall inclination angle of a single frustum of the frustum-shaped microarray structure is 60°, 62°, 64°, 65°, 66°, 68°, 70°, 72°, 74°, 75°, 76°, 78°, 80° or any two of the above values.

[0077] In one specific embodiment of the present invention, the frustum-shaped microarray structure comprises a third matrix resin, ZrO2 particles, and a third black filler; the third matrix resin is preferably one or more of epoxy resin, silicone resin, acrylic resin, and polyester resin; to meet the requirements of high light transmittance and high temperature resistance of the LED display surface, the third matrix resin is preferably polymethyl methacrylate, more preferably polymethyl methacrylate with a light transmittance greater than or equal to 92%; the particle size of the ZrO2 particles is preferably 10~100 nm; optionally, the particle size of the ZrO2 particles is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm. The ZrO2 particles are preferably 0.1% to 2% of the mass of the third matrix resin; optionally, the ZrO2 particles are 0.1%, 0.5%, 1%, 1.5%, 2% of the mass of the third matrix resin, or any two of the above values; the third black filler can be any black filler known to those skilled in the art, and there are no special limitations, including but not limited to one or more of carbon black, iron oxide, and carbon nanotubes; the particle size of the third black filler is preferably 10 to 100 nm; optionally, the particle size of the third black filler is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, or any two of the above values; the mass of the third black filler is preferably 0.1% to 2% of the mass of the third matrix resin; optionally, the mass of the third black filler is 0.1%, 0.5%, 1%, 1.5%, 2% of the mass of the third matrix resin, or any two of the above values.

[0078] In one specific embodiment of the present invention, the sidewall of each frustum of the frustum-shaped microarray structure is provided with a groove parallel to the LED display body, which significantly increases the actual physical area of ​​the sidewall surface and improves the total radiation power of the material; see also Figure 4 , Figure 4This diagram illustrates a frustum-shaped microarray structure with grooves on its sidewalls, where 3-1 represents a single frustum of the frustum-shaped microarray structure, and 302 represents a groove. The depth of the groove is preferably 1–8 μm; optionally, the groove depth is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, or any two of the above values. The groove depth is slightly smaller than the wavelength of infrared radiation in the atmospheric window (8–13 μm), belonging to a subwavelength structure. This subwavelength structure can effectively excite local surface plasmon resonance, phonon polaritons, or form an equivalent medium, thereby significantly enhancing the emissivity of the material in the atmospheric window band. Simultaneously, the presence of the groove breaks the limitations of a smooth surface, providing more modes for infrared photon emission and enhancing infrared emissivity. The width of the groove is preferably 1 to 10 μm. Optionally, the width of the groove is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or any two of the above values.

[0079] This invention constructs a radiation-cooling microstructure by setting a frustum-shaped microarray and a groove dual-scale scattering mechanism on the surface of the coating layer. The frustum-shaped microarray structure at the macro / submacro scale mainly solves the problem of broadband sunlight reflection; the groove structure at the micro / subwavelength scale, as a radiation groove, mainly solves the problem of emission enhancement in specific infrared bands. The main structure ensures strong reflection, while the secondary structure specifically enhances the infrared emission capability of the side without sacrificing the reflection performance of the main structure.

[0080] The present invention also provides a method for fabricating the above-mentioned LED display screen based on nano-coating technology, comprising the following steps: S1) providing an LED display screen body; S2) alternately depositing a low refractive index coating and a high refractive index coating on the light-emitting surface of the LED display screen body to form a coating layer; S3) using a photoresist process to expose and develop to form a photoresist layer with a frustum-shaped microarray structure model, fabricating a frustum-shaped microarray structure in the photoresist layer with the frustum-shaped microarray structure model, removing residual photoresist, and obtaining an LED display screen based on nano-coating technology.

[0081] This invention does not impose any special restrictions on the source of any raw materials; they can be commercially available.

[0082] In a specific embodiment of the present invention, the step of providing the LED display body preferably includes surface pretreatment; surface pretreatment can enhance surface adhesion and cleanliness; the surface pretreatment method is preferably plasma activation treatment; the plasma activation treatment preferably uses an atmospheric pressure argon / oxygen mixed plasma spray gun; the number of plasma activation treatments is preferably 2 to 4 times, more preferably 3 times; plasma activation treatment can remove organic pollutants and effectively improve surface energy.

[0083] In a specific embodiment of the present invention, a silica microporous array layer is preferably prepared on the surface of the LED display body after surface pretreatment; nanoscale roughening is achieved by preparing the silica microporous array layer, thereby improving the mechanical interlocking force of the cross section; specifically, the silica microporous array layer is formed by spraying an ethanol suspension containing silica nanoparticles and then curing it; more specifically, ultrasonic atomization is used to spray the ethanol suspension containing silica nanoparticles and then curing it to form the silica microporous array layer; the particle size of the silica nanoparticles is as described above and will not be repeated here; the mass concentration of silica nanoparticles in the ethanol suspension containing silica nanoparticles is preferably 1% to 10%; optionally, the mass concentration of silica nanoparticles in the ethanol suspension containing silica nanoparticles is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any two of the above values; the spraying amount of the ethanol suspension containing silica nanoparticles is preferably 20 to 50 mL / m 2 Optionally, the spraying amount of the ethanol suspension containing silica nanoparticles is 20 mL / m. 2 30 mL / m 2 40 mL / m 2 50 mL / m 2 Or any two of the above values; the curing is preferably performed using hot air; the curing temperature is preferably 60℃~90℃; optionally, the curing temperature is 60℃, 70℃, 80℃, 90℃ or any two of the above values; the curing time is preferably 5~20min; optionally, the curing time is 5 min, 10 min, 15 min, 20 min or any two of the above values.

[0084] In a specific embodiment of the present invention, a thermally conductive interface layer is preferably prepared on the surface of the silica microporous array layer away from the LED display body; the thickness and composition of the thermally conductive interface layer are as described above and will not be repeated here; specifically, in the present invention, a thermally conductive interface slurry is transferred to the surface of the silica microporous array layer away from the LED display body and cured to form a thermally conductive interface layer; the thermally conductive interface slurry includes a fourth matrix resin and aluminum nitride, preferably includes epoxy-type two-component reactive ink and aluminum nitride, more preferably includes YMD-HCP series screen-printed epoxy-type two-component reactive ink; the transfer method can be any method known to those skilled in the art and is not particularly limited, specifically screen printing transfer; the curing temperature is preferably 100℃~150℃; optionally, the curing temperature is 100℃, 110℃, 120℃, 130℃, 140℃, 150℃ or any two of the above values; the curing time is preferably 10~60 min; optionally, the curing time is 10 min, 20 min, 30 min, 40 min, 50 min. min, 60 min, or any two of the above values.

[0085] Alternating deposition of low-refractive-index and high-refractive-index coatings on the surface of the thermally conductive interface layer away from the LED display body forms a coating layer, achieving spectral selectivity control (high transmittance of visible light, high reflectance of near-infrared light, and high emissivity of mid-infrared light). The deposition method can be any method known to those skilled in the art and is not particularly limited. In this invention, it is preferred to form the coating by vaporizing a liquid precursor containing low-refractive-index nanoparticles or high-refractive-index nanoparticles and then depositing it.

[0086] In a specific embodiment of the present invention, the precursor solution for low-refractive-index coating deposition preferably includes a first matrix resin, ZrO2 particles, a first black filler, and low-refractive-index nanoparticles; the types and amounts of the first matrix resin, ZrO2 particles, first black filler, and low-refractive-index nanoparticles are the same as described above and will not be repeated here; the deposition temperature of the low-refractive-index coating is preferably 300℃~400℃; optionally, the deposition temperature of the low-refractive-index coating is 300℃, 320℃, 340℃, 360℃, 380℃, 400℃, or any two of the above values; the vacuum degree of the low-refractive-index coating deposition is preferably 0.5~2 torr; optionally, the vacuum degree of the low-refractive-index coating deposition is 0.5 torr, 1 torr, 1.5 torr, 2 torr, or any two of the above values; the deposition rate of the low-refractive-index coating is preferably 0.05~0.5 nm / cycle; optionally, the deposition rate of the low-refractive-index coating is 0.05 nm / cycle. nm / cycle, 0.08 nm / cycle, 0.1 nm / cycle, 0.1 nm / cycle, 0.11 nm / cycle, 0.15 nm / cycle, 0.2 nm / cycle, 0.3 nm / cycle, 0.4 nm / cycle, 0.5 nm / cycle, or any range between two of the above values.

[0087] In a specific embodiment of the present invention, the precursor solution for high refractive index coating deposition preferably includes a second matrix resin, ZrO2 particles, a second black filler, and high refractive index nanoparticles; the types and proportions of the second matrix resin, ZrO2 particles, second black filler, and high refractive index nanoparticles are the same as described above and will not be repeated here; the deposition temperature of the high refractive index coating is preferably 100℃~300℃; optionally, the deposition temperature of the high refractive index coating is 100℃, 120℃, 140℃, 160℃, 180℃, 200℃, 220℃, 240℃, 260℃, 280℃, 300℃, or any two of the above values; the vacuum degree of the high refractive index coating deposition is preferably 0.1~10 torr; optionally, the vacuum degree of the high refractive index coating deposition is 0.1 torr, 0.5 torr, 1 torr, 2 torr, 3 torr, 4 torr, 5 torr, 6 torr, 7 torr, 8 torr, 9 torr, 10 torr. The high refractive index coating deposition rate is preferably 0.04~0.06 nm / cycle; optionally, the high refractive index coating deposition rate is 0.04 nm / cycle, 0.05 nm / cycle, 0.06 nm / cycle, or any two of the above values.

[0088] In a specific embodiment of the present invention, it is preferable to perform in-situ optical detection after each deposition cycle, i.e., after depositing a low-refractive-index coating and a high-refractive-index coating; the in-situ optical detection specifically involves measuring the transmission and reflection spectra in the 400~2500 nm band.

[0089] In a specific embodiment of the present invention, to reduce the interlayer stress of the coating layer and improve the bonding stability between the coating layer and the LED display body and the coating layer, argon ion physical bombardment is preferably performed after each coating layer is deposited, and then the next coating layer is deposited; the energy of the argon ion physical bombardment is preferably 200~400 eV; optionally, the energy of the argon ion physical bombardment is 200 eV, 220 eV, 240 eV, 250 eV, 260 eV, 280 eV, 300 eV, 320 eV, 340 eV, 350 eV, 360 eV, 380 eV, 400 eV or any two of the above values; the time of the argon ion physical bombardment is preferably 1~5 min; optionally, the time of the argon ion physical bombardment is 1 min, 2 min, 3 min, 4 min, 5 min or any two of the above values; by using argon ion physical bombardment, the total thickness deviation of the coating is controlled to <±3%.

[0090] A photoresist layer with a frustum-shaped microarray structure model is formed by exposure and development using a photoresist process. A frustum-shaped microarray structure is then fabricated within this photoresist layer, resulting in an LED display screen based on nano-coating technology. In one specific embodiment of this invention, the surface of the coating layer is preferably cleaned and ensured to be highly flat before applying photoresist to facilitate uniform photoresist coating and pattern transfer. The cleaning method includes, but is not limited to, RCA cleaning and ultrasonic cleaning. In one specific embodiment of this invention, MicroChem SU-8 3000 photoresist is used to form the photoresist layer.

[0091] In a specific embodiment of the present invention, the photoresist process exposure and development steps are as follows: spin-coating a first photoresist onto the surface of the coating layer away from the LED display body, then pre-baking, then exposure, development, and etching; the spin-coating thickness of the first photoresist is preferably greater than or equal to the height of the frustum-shaped microarray structure, and further, it needs to be greater than the height of the frustum-shaped microarray structure; the exposure method can be any method known to those skilled in the art. Since the present invention forms a discontinuous three-dimensional structure, and since grayscale lithography technology is used, including but not limited to laser grayscale lithography technology, by controlling the spatial distribution of the exposure dose, the photoresist, after development, forms a photoresist layer with a frustum-shaped microarray structure model.

[0092] A frustum-shaped microarray structure is prepared in a photoresist layer with a frustum-shaped microarray structure model. Specifically, a precursor solution for forming the frustum-shaped microarray structure is added to the photoresist layer with the frustum-shaped microarray structure model, cured, residual photoresist after development is removed, the surface is cleaned, and a frustum-shaped microarray structure is formed on the surface of the coating layer. The precursor solution for forming the frustum-shaped microarray structure includes a third matrix resin, ZrO2 particles, and a third black filler. The types and amounts of the third matrix resin, ZrO2 particles, and third black filler are the same as described above and will not be repeated here. The curing temperature is preferably 80℃~120℃. Optionally, the curing temperature is 80℃, 90℃, 100℃, 110℃, 120℃, or any two of the above values. The curing time is preferably 30~90 min. Optionally, the curing time is 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, or any two of the above values.

[0093] In one specific embodiment of the present invention, a groove is further prepared on the sidewall of a single frustum of the frustum-shaped microarray structure as a secondary radiation groove. The method for preparing the groove can be carried out according to methods well known to those skilled in the art. Specifically, the groove can be formed by exposing, developing, and etching the sidewall of a single frustum of the frustum-shaped microarray structure using a second photoresist to obtain an LED display screen based on nanofilm coating technology. More specifically, a second photoresist is coated on the frustum-shaped microarray structure, followed by exposure, development, and sidewall etching. Since the surface of the frustum-shaped microarray structure is uneven, the second photoresist is preferably a photoresist with good fluidity and strong gap-filling ability (such as a specially formulated thick photoresist or spin-coated glass material), or a sacrificial layer (such as amorphous carbon or SiO2) can be deposited conformally by chemical vapor deposition (CVD) as a planarization layer, and then the second photoresist can be coated on top. The etching process involves: During polishing, a high-precision overlay alignment system is preferred to accurately align the pattern of the radiation groove to the sidewall region of the trapezoidal structure; During exposure, the influence of the non-planar substrate needs to be considered; therefore, this invention preferably utilizes a combination of electron beam lithography (EBL), extreme ultraviolet lithography (EUV), or deep ultraviolet lithography (DUV) with optimized processes to achieve the required precision (groove width may range from submicron to several micrometers) and overlay accuracy selection; During development, precise control is required to ensure that windows are opened only in the sidewall region where the grooves need to be etched; The etching method used for testing can be any method well-known to those skilled in the art, specifically a highly anisotropic dry etching process, including but not limited to reactive ion etching (RIE), inductively coupled plasma-reactive ion etching (ICP-RIE), etc., to etch grooves on the sidewalls of individual frustums of the frustum-shaped microarray structure.

[0094] In one specific embodiment of the present invention, after etching to form a groove, the second photoresist is removed. If there is a planarization sacrificial layer, the planarization sacrificial layer also needs to be removed. After cleaning, an LED display screen based on nano-coating technology is obtained.

[0095] To further illustrate the present invention, the following describes in detail, with reference to embodiments, an LED display screen based on nano-coating technology and its preparation method.

[0096] All reagents used in the following examples are commercially available.

[0097] Example 1

[0098] 1.1 Provide LED display body: module size is 125×250 mm, and the power consumption of a single module is 38 W.

[0099] 1.2 Plasma activation: Using an atmospheric pressure argon / oxygen mixed plasma spray gun, the light-emitting surface of the LED display body is cyclically treated 3 times, which can remove organic pollutants and effectively improve surface energy.

[0100] 1.3 Nanoscale roughening: Ultrasonic atomization was used to spray an ethanol suspension containing 5 wt% SiO2 nanoparticles (50 nm in diameter), controlling the total spraying amount to 50 mL / m. 2 Curing is carried out at 80°C for 10 minutes to form a micro-pit array, which enhances the mechanical interlocking force at the interface.

[0101] 1.4 Thermal interface layer coating: screen-printed aluminum nitride (particle size 40 nm) / epoxy resin composite paste (YMD-HCP series screen-printed epoxy two-component reactive ink), the amount of aluminum nitride in the paste is 10% of the resin mass, the thickness is controlled at 50±5 μm, and cured at 120°C for 30 min.

[0102] 1.5 Deposited Coating Layer:

[0103] Materials: To meet the requirements of high light transmittance and high temperature resistance of LED lamp surface, PMMA (Taiwan Chi Mei CM211) with transmittance ≥92% is used as the base material. Based on the quality of the base material, 0.5wt% ZrO (particle size 30 nm) and 0.5wt% carbon nanotubes (particle size 30 nm) are added to it to prepare the base solution.

[0104] Take a portion of the base solution and add 2.5 wt% TiO2, a high refractive index material, to prepare a high refractive index solution.

[0105] Take another portion of the base solution and add 10 wt% SiO2, a low-refractive-index material, to prepare a low-refractive-index solution.

[0106] The material is composed of two materials stacked alternately, with the number of layers controlled at 8 and the thickness of each layer controlled in the range of 200±10% nm.

[0107] First layer deposition (low refractive index layer):

[0108] Material selection: Low refractive index solution (SiO2 particle size 50 nm);

[0109] Process parameters: Deposition temperature 300℃, vacuum degree 1 torr;

[0110] Deposition rate: 0.11 nm / cycle, thickness controlled at 200±20 nm;

[0111] Second deposition layer (high refractive index layer):

[0112] Material selection: High refractive index solution (TiO2 particle size 50 nm);

[0113] Process parameters: Deposition temperature 100℃, vacuum degree 1 torr;

[0114] Deposition rate: 0.06 nm / cycle, thickness controlled at 200±20 nm;

[0115] Cyclic deposition and monitoring:

[0116] Repeat the above process until there are 8 layers (4 low-refractive-index layers + 4 high-refractive-index layers alternately).

[0117] In-situ optical testing was performed on every two layers: the transmission / reflection spectra in the 400~2500nm band were measured, the transmittance in the 400~800nm ​​band was >75%, and the reflectance in the 800~2500nm band was >90%;

[0118] Interlayer stress control: After each layer is deposited, Ar⁺ bombardment (energy 300eV) is performed for 3 minutes to release film stress, and the total thickness deviation is controlled to <±3%.

[0119] 1.6 Surface treatment: The surface of the coating layer is cleaned by using radio frequency or microwave energy to generate plasma, which can effectively and thoroughly clean and activate the surface.

[0120] 1.7 Main Trapezoidal Array Photolithography and Forming:

[0121] Spin-coat a thick photoresist (MicroChem SU-8 3000, thickness >30μm, preferably slightly larger than the height of the trapezoid) and pre-bake.

[0122] A 3D structure with a trapezoidal cross-sectional profile is directly formed on photoresist using grayscale lithography or laser direct writing. Development is performed using 2.38% AZ 326 MIF: 1) Preparation and Fixation: Securely attach the exposed coated display module to the spin coater base; 2) Pouring Developer: Start the spin coater and rotate at a low speed (e.g., 500 rpm), smoothly pouring a sufficient amount of AZ® 326 MIF developer onto the center of the substrate until the liquid film covers the entire surface; 3) Static Immersion: Stop rotation and allow the developer to statically immerse the substrate surface. Simultaneously start the timer; 5) Dynamic Development: After static immersion, restart the spin coater and rotate at a low speed (e.g., 500 rpm). Simultaneously, gently spray a small amount of developer or deionized water using a wash bottle to rinse away the reaction products; 6) Rinse: Turn off the developer and immediately rinse the substrate surface with plenty of deionized water to completely stop the development reaction and remove all developer residue; 7) Dry: Use a nitrogen gun or compressed air to dry the substrate surface. A spin dryer can also be used for drying.

[0123] After development, the photoresist itself forms a trapezoidal array (trapezoidal base 50 μm, tilt angle 70°, spacing 50 μm) mold. Then, the substrate solution prepared in step 1.5 is added, with the addition height controlled at 30 μm. It is cured at 120℃ for 60 min to completely remove residual photoresist. The surface is cleaned to obtain a regular square frustum-shaped microarray structure (each frustum has a top edge of 20 μm, a bottom edge of 50 μm, a tilt angle of 70°, a height of 30 μm, and a spacing of 50 μm).

[0124] 1.8 Photolithography and etching of secondary radiation trenches:

[0125] Photoresist coating. Photoresist (MicroChem SU-83000) is spin-coated again onto the formed trapezoidal array structure. Centrifugal force is used to spread it into an ultra-thin, uniform film. Pre-baking is performed on a hot plate to evaporate most of the solvent in the photoresist, so that it can be cured and stabilized, while improving adhesion. Typical baking conditions are about 100°C for 1 minute.

[0126] Alignment and Exposure: A precision mechanical system aligns the pattern on the photomask with the existing markings on the substrate. Then, 193nm deep ultraviolet light passes through the photomask, through an immersion solution (water), and a projection lens to form a potential pattern on the photoresist.

[0127] Post-exposure baking: The exposed substrate is placed on a hot plate and precisely heated to 110°C for 1 minute. The heat causes the photoacid to act as a catalyst, significantly accelerating the changes in soluble groups in the photoresist, thereby greatly improving the sensitivity of the photoresist.

[0128] Development: 2.38% AZ 326 MIF was used as the developer. In positive photoresist, the exposed areas become soluble after PEB and are dissolved by the developer, thus accurately replicating the pattern on the mask onto the photoresist.

[0129] Hard baking: A second baking process is performed to completely remove residual solvents and moisture, and to further improve the hardness, adhesion and etching resistance of the photoresist, preparing it for subsequent ion implantation or etching processes.

[0130] Sidewall etching: A 5 μm deep groove was etched into the trapezoidal sidewall using highly anisotropic reactive ion etching (RIE).

[0131] Photoresist removal / sacrificial layer removal and final cleaning: Thoroughly remove all photoresist layers and perform a final thorough cleaning.

[0132] Example 2

[0133] The preparation method is the same as in Example 1, except that the thickness of the low refractive index layer and the high refractive index layer are different, both being 100 mm.

[0134] The test results are shown in Table 1.

[0135] Example 3

[0136] The preparation method is the same as in Example 1, except that the amount of SiO2 added in the low refractive index layer is 5% and the amount of TiO2 added in the high refractive index layer is 0.5%.

[0137] The test results are shown in Table 1.

[0138] Example 4

[0139] The preparation method is the same as in Example 1, and the number of stacked layers is 6 (3 low refractive index layers + 3 high refractive index layers alternately).

[0140] The test results are shown in Table 1.

[0141] Example 5

[0142] The preparation method is the same as in Example 1, except that there are no grooves on the sidewalls.

[0143] The test results are shown in Table 1.

[0144] Comparative Example 1

[0145] The preparation method is the same as in Example 1, except that steps 1.6 to 1.8 are omitted, and only the coating layer is formed.

[0146] The test results are shown in Table 1.

[0147] Comparative Example 2

[0148] The preparation method is the same as in Example 1. There is no coating on the surface of the LED display body. After coating the thermal interface layer, steps 1.6 to 1.8 are directly performed to prepare the main trapezoidal array and the secondary radiation groove.

[0149] The test results are shown in Table 1.

[0150] Comparative Example 3

[0151] The preparation method is the same as in Example 1, except that the number of stacked layers is 2 (1 low refractive index layer + 1 high refractive index layer alternately).

[0152] The test results are shown in Table 1.

[0153] The performance of the LED display screen itself and the LED display screen was tested:

[0154] Surface temperature test: The treated LED module was lit outdoors (module power 38W, LED heat flux density 0.0288 W / mm²). 2The brightness was adjusted to the maximum and the module was operated for 8 hours. Five test points (top left, bottom left, middle, top right, and bottom right) were taken on the surface of the LED module. The temperature data were measured with thermocouples and the average value was calculated. The results are shown in Table 1.

[0155] Transmission and reflection: Performed according to the general rules of ultraviolet and visible light absorption spectroscopy analysis method JY / T 0570-2020. Instrument: Perkins Elmer Lambda 950, USA. The results are shown in Table 1.

[0156] Emission: Using an FTIR spectrometer with an integrating sphere attachment, the hemispherical reflectance spectrum of the material in the infrared band (typically 4-40 μm, especially the 8-13 μm atmospheric window band) was measured, and the results are shown in Table 1.

[0157] Table 1 LED Module Performance Test

[0158]

[0159] As shown in Table 1, the LED display module etched using the coating structure and array structure provided by this invention has high transmittance in 0.3~0.8 μm, high reflectivity in 0.8~2.5 μm, and high emissivity in 8~13 μm; it can reduce the temperature of the lamp surface by 4℃~9℃, and the cooling effect increases with the increase of solar irradiance.

[0160] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An LED display screen based on nano-coating technology, characterized in that, include: LED display screen body; The light-emitting surface of the LED display screen body is provided with a coating layer; The surface of the coating layer away from the LED display body is provided with a frustum-shaped microarray structure. The coating layer includes alternating low-refractive-index coatings and high-refractive-index coatings; one alternating layer of the low-refractive-index coating and one alternating layer of the high-refractive-index coating constitutes one cycle; in each cycle, the high-refractive-index coating is disposed on the surface of the low-refractive-index coating that is away from the LED display body; The low-refractive-index coating comprises low-refractive-index nanoparticles; the refractive index of the low-refractive-index nanoparticles is less than or equal to 2; the high-refractive-index coating comprises high-refractive-index nanoparticles; the refractive index of the high-refractive-index nanoparticles is greater than 2.

2. The LED display screen according to claim 1, characterized in that, The side length of the surface of a single frustum away from the LED display body of the frustum-shaped microarray structure is 10~30 μm; the side length of the bottom surface of a single frustum in contact with the LED display body is 30~70 μm. The height of the frustum-shaped microarray structure is 10~50 μm; The spacing between adjacent individual frustums in the frustum-shaped microarray structure is 30~70 μm; The sidewall inclination angle of a single frustum in the frustum-shaped microarray structure is 60°~80°.

3. The LED display screen according to claim 2, characterized in that, The sidewall of each frustum of the frustum-shaped microarray structure is provided with a groove parallel to the LED display body; the depth of the groove is 1~8 μm. The width of the groove is 1~10 μm.

4. The LED display screen according to claim 1, characterized in that, The thickness of the low-refractive-index coating in each cycle is independently 100~300 nm; The thickness of the high-refractive-index coating in each cycle is independently 100~300 nm; The number of alternating cycles is 2 to 6.

5. The LED display screen according to claim 1, characterized in that, The low-refractive-index coating comprises a first matrix resin, ZrO2 particles, a first black filler, and low-refractive-index nanoparticles. The low-refractive-index nanoparticles have a particle size of 10~100 nm; The mass of the low-refractive-index nanoparticles is 1% to 20% of the mass of the first matrix resin; The low-refractive-index nanoparticles are selected from one or more of SiO2 particles, Si3N4 and Al2O3 particles; The high refractive index coating comprises a second matrix resin, ZrO2 particles, a second black filler, and high refractive index nanoparticles. The high-refractive-index nanoparticles have a particle size of 10~100 nm; The mass of the high refractive index nanoparticles is 1% to 10% of the mass of the second matrix resin; The high refractive index nanoparticles are selected from one or more of TiO2 particles, Si3N4 particles and ZnS particles.

6. The LED display screen according to claim 5, characterized in that, The mass of ZrO2 particles in the low-refractive-index coating is 0.1% to 2% of the mass of the first matrix resin; The mass of the first black filler is 0.1% to 2% of the mass of the first matrix resin; The mass of ZrO2 particles in the high refractive index coating is 0.1% to 2% of the mass of the second matrix resin; The mass of the second black filler is 0.1% to 2% of the mass of the second matrix resin; The frustum-shaped microarray structure includes a third matrix resin, ZrO2 particles, and a third black filler. The mass of ZrO2 particles in the frustum-shaped microarray structure is 0.1% to 2% of the mass of the third matrix resin; The mass of the third black filler is 0.1% to 2% of the mass of the third matrix resin.

7. The LED display screen according to claim 6, characterized in that, The first matrix resin, the second matrix resin, and the third matrix resin are each independently selected from one or more of epoxy resin, silicone resin, acrylic resin, and polyester resin; The particle size of ZrO2 particles in the low-refractive-index coating, the high-refractive-index coating, and the frustum-shaped microarray structure is independently 10~100 nm. The first black filler, the second black filler, and the third black filler are each independently selected from one or more of carbon black, iron oxide, and carbon nanotubes; The particle sizes of the first, second, and third black fillers are each independently 10~100 nm.

8. The LED display screen according to claim 1, characterized in that, A thermally conductive interface layer is also provided between the LED display body and the coating layer; the thermally conductive interface layer includes a fourth matrix resin and aluminum nitride; the thickness of the thermally conductive interface layer is 10~100 μm.

9. The LED display screen according to claim 8, characterized in that, A silica microporous array layer is also provided between the LED display body and the thermal interface layer; the silica microporous array layer is formed by silica nanoparticles; the particle size of the silica nanoparticles is 10~100 nm.

10. A method for preparing an LED display screen based on nano-coating technology as described in claim 1, characterized in that, Includes the following steps: S1) Provides the LED display screen body; S2) Alternately deposit low-refractive-index coatings and high-refractive-index coatings on the light-emitting surface of the LED display body to form a coating layer; S3) Using photoresist process, exposure and development are performed to form a photoresist layer with a frustum-shaped microarray structure model. A frustum-shaped microarray structure is prepared in the photoresist layer with the frustum-shaped microarray structure model to obtain an LED display screen based on nano-coating technology.

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