LED device, preparation method and LED display screen

Abstract

The invention provides an LED device, a preparation method and an LED display screen, the LED device comprises a light-emitting assembly, and the light-emitting assembly comprises a substrate, and a red light-emitting chip, a green light-emitting chip and a blue light-emitting chip which are arranged on the substrate at intervals. A first graphene heat radiation layer is arranged on the outer layers of the light-emitting chips, a packaging adhesive layer covers the first graphene heat radiation layer and the substrate, and a second graphene heat radiation layer is further arranged on the outer layer of the packaging adhesive layer, so that a double-layer graphene heat radiation structure is formed. According to the double-layer graphene heat radiation structure, the heat exchange capacity of the LED device and the external environment can be remarkably enhanced, generated heat can be quickly and efficiently dissipated, the working temperature of a light-emitting chip is effectively reduced, and performance degradation or damage caused by high temperature is avoided.

Description

Technical Field

[0001] The present application belongs to the technical field of display devices, and more specifically, relates to an LED device and a preparation method thereof, and an LED display screen. Background Art

[0002] As the core of modern display technology, LED display screens are widely used in outdoor advertising, interior decoration, stage performances and other fields with their significant advantages such as high brightness, high contrast and long life. However, after long-term working, LED display screens often face the problem of blue screen, which is mainly caused by the brightness attenuation of red light LEDs based on aluminum gallium indium phosphide (AlGaInP) materials.

[0003] Although AlGaInP material is one of the most mature semiconductor materials for making red light LEDs, it has the characteristics of low cost, high brightness and good reliability. However, during the long-term lighting process, the brightness decays rapidly due to changes in the internal structure of the material and the electron migration characteristics. This instability is one of the important reasons for the brightness decay of red light LED chips. In addition, although the LED chip is encapsulated in epoxy resin, it plays a role in protection and insulation, but it also leads to a decrease in heat dissipation efficiency. Especially under high brightness and long-term working conditions, the heat generated by the LED chip cannot be dissipated in time, resulting in excessive chip temperature. High temperature not only accelerates the aging and structural changes of the material, but also reduces the efficiency of electron-hole recombination, thereby further exacerbating the brightness decay.

[0004] With the development of micro-pitch LED display panels, higher requirements are placed on the luminous efficiency of chip size at the micron scale. However, AlGaInP materials are severely affected by the "size effect" at the micron scale, and the luminous efficiency drops significantly, which has become a recognized problem in the industry. This is mainly because as the chip size decreases, the carrier diffusion length and surface recombination velocity of the material change, resulting in a significant decrease in luminous efficiency. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide an LED device and a preparation method, and an LED display screen, so as to solve the technical problem in the prior art that the heat dissipation effect of the LED chip is poor, resulting in the attenuation of the LED brightness.

[0006] To achieve the above purpose, the technical solution adopted in this application is:

[0007] Provided is an LED device, comprising:

[0008] A light-emitting component, comprising a substrate and a red light-emitting chip, a green light-emitting chip and a blue light-emitting chip arranged on the substrate at intervals;

[0009] A first graphene heat radiation layer is disposed on the outer layer of the red light emitting chip, the green light emitting chip and the blue light emitting chip;

[0010] A packaging adhesive layer, disposed on the first graphene heat radiation layer and the substrate;

[0011] The second graphene heat radiation layer is arranged on the top surface of the packaging glue layer.

[0012] This double-layer graphene thermal radiation structure can significantly enhance the heat exchange capacity between LED devices and the external environment, allowing the generated heat to be dissipated quickly and efficiently, effectively reducing the operating temperature of the light-emitting chip and avoiding performance degradation or damage caused by high temperature.

[0013] As a further improvement of the above technical solution:

[0014] Optionally, the thickness of the first graphene heat radiation layer is in the range of 2 μm-5 μm, which can achieve both good light transmittance and efficient heat conduction to prevent local overheating of the light-emitting chip.

[0015] Optionally, the second graphene heat radiation layer has a thickness ranging from 2 μm to 5 μm, which can achieve both good light transmittance and efficient heat conduction to prevent local overheating of the light-emitting chip.

[0016] Optionally, the red light emitting chip includes a blue light emitting source core, a red light color conversion layer disposed on the surface of the blue light emitting source core, and a red light filter layer disposed on the surface of the red light color conversion layer.

[0017] Optionally, the green light emitting chip includes a blue light source core, a green light color conversion layer disposed on the surface of the blue light source core, and a green light filter layer disposed on the surface of the green light color conversion layer.

[0018] Optionally, the blue light emitting chip includes a blue light emitting source core and a blue light filter layer disposed on the surface of the blue light emitting source core.

[0019] The present application also provides a method for preparing an LED device, comprising the following steps:

[0020] S0: providing a plurality of blue light emitting chips, wherein the blue light emitting chips include a blue light emitting source core and a sapphire substrate disposed on the blue light emitting source core;

[0021] S1: Obtain a blue light emitting source core, and use a laser lift-off device to remove the sapphire substrate of the blue light emitting chip to obtain the blue light emitting source core;

[0022] S2: Add a red / green conversion layer, and add a red light color conversion layer / green light color conversion layer on the side and top surface of the blue light source core;

[0023] S3: Add red / green / blue filter layers, add red filter layers and green filter layers on the surfaces of the red light color conversion layer and the green light color conversion layer respectively, take the blue light emitting source core described in S1, and add a blue light filter layer on the surface of the blue light emitting source core;

[0024] S4: adding a first graphene heat radiation layer, and adding a first graphene heat radiation layer on the surface of the red light filter layer / the green light filter layer / the blue light filter layer;

[0025] S5: preparing RGB sub-pixels, combining the chips with the first graphene heat radiation layer added in S4 into a light-emitting combination including a red light-emitting chip, a green light-emitting chip and a blue light-emitting chip, transferring and installing them on a substrate, and then adding a packaging glue layer on the surface;

[0026] S6: adding a second graphene heat radiation layer, and adding a second graphene heat radiation layer on the surface of the packaging glue layer.

[0027] As a further improvement of the above technical solution:

[0028] Optionally, when adding a red / green conversion layer, an inkjet printer or photolithography equipment is used to coat the sides and top surface of the blue light source core with red light quantum dot photoluminescent material to form a red light color conversion layer; and green light quantum dot photoluminescent material is coated on the sides and top surface of the blue light source core to form a green light color conversion layer.

[0029] Optionally, the thickness of the red light color conversion layer and the green light color conversion layer are both in the range of 100 nm to 2000 nm.

[0030] Optionally, the red light filter layer allows red light with a wavelength range of 620nm-640nm to pass through, the green light filter layer allows green light with a wavelength range of 520nm-540nm to pass through, and the blue light filter layer allows blue light with a wavelength range of 450nm-460nm to pass through.

[0031] The present application also provides an LED display screen, comprising the above-mentioned LED device.

[0032] The beneficial effects of an LED device, a preparation method, and an LED display provided by the present application are:

[0033] The LED device provided in the present application includes a light-emitting component, a first graphene heat radiation layer 4, an encapsulation glue layer 5 and a second graphene heat radiation layer. Among them, the light-emitting component includes a substrate and a red light-emitting chip, a green light-emitting chip and a blue light-emitting chip arranged on the substrate. In order to effectively solve the problem of heat accumulation generated by the red, green and blue light-emitting chips during operation, a first graphene heat radiation layer is arranged on the outer layer of the red light-emitting chip, the green light-emitting chip and the blue light-emitting chip. In order to consolidate the structural stability of the LED device, a layer of encapsulation glue layer is also covered on the first graphene heat radiation layer and the substrate. The encapsulation glue layer is not only used to solidify the position of the red, green and blue light-emitting chips relative to the substrate, but also protects the red, green and blue light-emitting chips and the substrate, thereby extending the service life of the LED. In order to further enhance the heat dissipation efficiency of the LED device of the present application, a second graphene heat radiation layer is also arranged on the outer layer of the encapsulation glue layer, thereby forming a double-layer graphene heat radiation structure. This double-layer graphene thermal radiation structure can significantly enhance the heat exchange capacity between LED devices and the external environment, allowing the generated heat to be dissipated quickly and efficiently, effectively reducing the operating temperature of the light-emitting chip and avoiding performance degradation or damage caused by high temperature.

[0034] The LED display screen also provided in the present application includes the above-mentioned LED device and also has the advantages of the above-mentioned LED device. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 A schematic cross-sectional view of the LED device provided in this application;

[0037] Figure 2 A flow chart of a method for preparing an LED device provided in this application;

[0038] Figure 3 A schematic diagram of the process of step 1 of the LED device provided in this application;

[0039] Figure 4 A schematic diagram of the process of step 2 of the LED device provided in this application;

[0040] Figure 5 A schematic diagram of the process of step 3 of the LED device provided in this application;

[0041] Figure 6 A schematic diagram of the process of step 4 of the LED device provided in this application;

[0042] Figure 7 A schematic diagram of the process of step 5 of the LED device provided in this application;

[0043] Figure 8 A schematic diagram of the process of step 6 of the LED device provided in this application;

[0044] Figure 9a This is the front view of thermal imaging of a traditional LED device;

[0045] Figure 9b Thermal imaging left / right view of a conventional LED device;

[0046] Fig.9c Thermal imaging top / bottom view of a conventional LED device;

[0047] Fig.10a Thermal imaging front view of the LED device provided for this application;

[0048] Fig.10b Thermal imaging left / right view of the LED device provided for this application;

[0049] Fig.10c Thermal imaging top / bottom view of the LED device provided for this application.

[0050] Among them, the reference numerals in the figure are:

[0051] 1. Red light emitting chip; 11. Red light color conversion layer; 12. Red light filter layer;

[0052] 2. Green light emitting chip; 21. Green light color conversion layer; 22. Green light filter layer;

[0053] 3. Blue light emitting chip; 31. Blue light source core; 311. Upper conductive layer; 312. Photovoltaic material layer; 313. Lower conductive layer; 314. Bragg reflection layer; 315. Metal P-level electrode; 316. Metal N-level electrode; 32. Blue light filter layer;

[0054] 4. The first graphene heat radiation layer;

[0055] 5. Encapsulation adhesive layer;

[0056] 6. The second graphene heat radiation layer. DETAILED DESCRIPTION

[0057] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0058] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0059] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0060] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0061] like Figure 1 As shown, the present application provides an LED device with more efficient heat dissipation, and the LED device specifically refers to a flip-chip Micro-LED device packaged by Mip (Mini / Micro LED in Package) packaging technology. The LED device includes a light-emitting component, a first graphene heat radiation layer 4, a packaging glue layer 5, and a second graphene heat radiation layer. Among them, the light-emitting component includes a substrate (not shown) and a red light-emitting chip 1, a green light-emitting chip 2, and a blue light-emitting chip 3 arranged on the substrate.

[0062] In order to effectively solve the problem of heat accumulation generated by the red, green and blue light-emitting chips during operation, a first graphene heat radiation layer 4 is provided on the outer layer of the red light-emitting chip 1, the green light-emitting chip 2 and the blue light-emitting chip 3. The first graphene heat radiation layer 4 is a single-layer graphene, which is a two-dimensional carbon material composed of a layer of carbon atoms periodically and closely stacked in a benzene ring structure (i.e., a hexagonal honeycomb structure). It can be deposited on the surface of the light-emitting chip by process technologies such as magnetron sputtering technology and spraying technology. Graphene has very excellent thermal conductivity. The thermal radiation coefficient of pure and defect-free single-layer graphene is as high as 5300W / mK, which is higher than 3500W / mK of single-walled carbon nanotubes and 3000W / mK of multi-walled carbon nanotubes. When it is used as a carrier, the thermal radiation coefficient can also reach 600W / mK. In addition, graphene has good optical properties, with an absorption rate of about 2.3% in a wide wavelength range, and appears almost transparent. Therefore, it has little impact on the light emitted by the red, green and blue light-emitting chips, ensuring that the brightness of the light output is not lost.

[0063] In order to consolidate the structural stability of the LED device, a layer of encapsulation glue layer 5 is also covered on the first graphene thermal radiation layer 4 and the substrate. The encapsulation glue layer 5 is not only used to solidify the position of the red, green and blue light-emitting chip relative to the substrate, but also protects the red, green and blue light-emitting chip and the substrate, thereby extending the service life of the LED. The encapsulation glue layer 5 is selected because of its low absorption of light and its ability to protect the light-emitting chip from being damaged by external forces to a large extent. The material of the encapsulation glue layer 5 can be a thermoplastic film such as EVA, TPU, POM, or a pre-cured film of encapsulation glue such as epoxy resin and organic silicone. The thickness of the encapsulation glue layer 5 needs to be higher than the height of the above-mentioned red, green and blue light-emitting chip.

[0064] In order to further enhance the heat dissipation efficiency of the LED device of the present application, a second graphene heat radiation layer 6 is further provided on the outer layer of the encapsulation adhesive layer 5, thereby forming a double-layer graphene heat radiation structure. This double-layer graphene heat radiation structure can significantly enhance the heat exchange capacity between the LED device and the external environment, so that the generated heat can be dissipated quickly and efficiently, effectively reducing the operating temperature of the light-emitting chip and avoiding performance degradation or damage caused by high temperature.

[0065] like Figure 1 As shown, in one embodiment of the present application, the red light emitting chip 1, the green light emitting chip 2 and the blue light emitting chip 3 are arranged at intervals from each other, so that the first graphene thermal radiation layer 4 can be coated on the side and top surfaces of the red light emitting chip 1, the green light emitting chip 2 and the blue light emitting chip 3, so that the heat distribution on the light emitting chip is more balanced, the occurrence of local overheating is prevented, and the reliability and service life of the entire LED device are further improved.

[0066] In one embodiment of the present application, the thickness of the first graphene heat radiation layer 4 is in the range of 2 μm-5 μm. Considering the light transmittance and thermal conductivity of the first graphene heat radiation layer 4, the thickness of the first graphene heat radiation layer 4 is specifically selected to be 2 μm, which can achieve both good light transmittance and efficient heat conduction, thereby preventing local overheating of the light-emitting chip.

[0067] In one embodiment of the present application, the thickness of the second graphene heat radiation layer 6 is also in the range of 2 μm-5 μm. Taking into account the light transmittance and thermal conductivity of the second graphene heat radiation layer 6, the optimal thickness of the second graphene heat radiation layer 6 is 2 μm. When the thickness is too thin, the thermal conductivity of the second graphene heat radiation layer 6 is insufficient; when the thickness is too thick, the light transmittance of the second graphene heat radiation layer 6 is poor.

[0068] like Figure 1 As shown, in one embodiment of the present application, the blue light emitting chip 3 includes a blue light emitting source core 31. The blue light emitting source core 31 specifically includes an upper conductive layer 311, a photovoltaic material layer 312, a lower conductive layer 313, a Bragg reflection layer 314, a metal P-level electrode 315, and a metal N-level electrode 316. The upper conductive layer 311 and the lower conductive layer 313 are made of N-GaN material and P-GaN material, respectively, and their thicknesses are both 25μm; the photovoltaic material layer 312 is made of InGaN material, and its luminous wavelength is in the spectral range of 450nm-460nm, and the thickness of the photovoltaic material layer 312 is in the range of 5μm-10μm; the metal P-level electrode 315 and the metal N-level electrode 316 can be made of materials such as gold, nickel, titanium, copper, and aluminum, wherein the thickness of the metal P-level electrode 315 is 10μm, and the thickness of the metal N-level electrode 316 is 60μm.

[0069] Since the blue light source core 31 has an asymmetric light emission problem, in order to make the transmitted blue light emit more uniformly and increase the blue light viewing angle of the display screen, a blue light filter layer 32 is covered on the surface of the blue light source core 31. The blue light filter layer 32 only allows blue light with a wavelength range of 450nm-460nm to pass through. The thickness of the blue light filter layer 32 is specifically 2μm.

[0070] like Figure 1 As shown, in one embodiment of the present application, the red light emitting chip 1 includes a blue light source core 31 , a red light color conversion layer 11 disposed on the surface of the blue light source core 31 , and a red light filter layer 12 disposed on the surface of the red light color conversion layer 11 .

[0071] The quantum dot material of the red light color conversion layer 11 is cadmium quantum dots CdSe / ZnSQDs or indium phosphide InP / ZnSQDs. Specifically, red light quantum dots with a luminous wavelength in the spectral range of 620nm-640nm can be selected, with a photoluminescence quantum yield greater than 90% and a half-peak width of about 25nm. When preparing the red light color conversion layer 11, the quantum dot material is dissolved in a volatile solvent, isopropanol, with a concentration of 5mg / mL-10mg / mL and a density of 0.895g / cm 3 Then, the red light quantum dot color conversion layer 11 is deposited on the blue light source core 31 by inkjet printing technology, photolithography technology, nanoimprint technology, etc., with a deposition thickness of about 100nm-2000nm. The function of the red light color conversion layer 11 is to convert the blue light emitted by the blue light source core 31 into red light and increase the viewing angle of the red light.

[0072] The red light filter layer 12 only allows red light with a wavelength range of 620nm-640nm to pass through. The thickness of the red light filter layer 12 is specifically 2μm. The red light filter layer 12 is used to prevent the leakage of blue light in the red light color conversion layer 11 and isolate the blue light color crosstalk to obtain a purer red light.

[0073] like Figure 1 As shown, in one embodiment of the present application, the green light emitting chip 2 includes a blue light source core 31 , a green light color conversion layer 21 disposed on the surface of the blue light source core 31 , and a green light filter layer 22 disposed on the surface of the green light color conversion layer 21 .

[0074] The quantum dot material of the green light color conversion layer 21 is cadmium quantum dots CdSe / ZnSQDs or indium phosphide InP / ZnSQDs. Specifically, green light quantum dots with a luminous wavelength in the spectral range of 520nm-540nm can be selected, with a photoluminescence quantum yield greater than 90% and a half-peak width of about 22nm. When preparing the green light color conversion layer 21, the quantum dot material is dissolved in a volatile solvent, isopropanol, with a concentration of 5mg / mL-10mg / mL and a density of 0.895g / cm 3 Then, the green light color conversion layer 21 is deposited on the blue light source core 31 by inkjet printing technology, photolithography technology, nanoimprint technology, etc., with a deposition thickness of about 100nm-2000nm. The function of the green light color conversion layer 21 is to convert the blue light emitted by the blue light source core 31 into green light and increase the viewing angle of the green light.

[0075] The green filter layer 22 only allows green light with a wavelength range of 520nm-540nm to pass through. The thickness of the green filter layer 22 is specifically 2μm. The green filter layer 22 is used to prevent the blue light from leaking out of the green light color conversion layer 21 and isolate the blue light color crosstalk to obtain a purer green light.

[0076] like Figures 2 to 8 As shown, the present application provides a method for preparing an LED device, which specifically includes the following steps:

[0077] (0) A plurality of blue light emitting chips 3 are provided. The blue light emitting chips 3 include a blue light emitting source core 31 and a sapphire substrate disposed on the blue light emitting source core 31 .

[0078] (1) Obtaining the blue light source core

[0079] Existing red LED chips generally use standard-sized aluminum gallium indium phosphide (AlGaInP) as their core material. When these chips are reduced to micro-nano sizes, the chip surface recombination phenomenon becomes particularly prominent due to the high minority carrier diffusion length, which directly leads to a significant decrease in photoelectric conversion efficiency. If you try to integrate AlGaInP material with blue LED chips and green LED chips based on InGaN materials in a pixel unit, it is easy to cause the pixel to have poor mechanical properties and low thermal stability. In addition, the sapphire substrate material in the LED chip inevitably restricts the luminous efficiency of the LED due to its inherent low thermal conductivity and electrical conductivity. In addition, the brittle nature of the sapphire substrate has become a major obstacle for Micro LED chips in the pursuit of flexible applications, seriously hindering the maturity and development of smaller and more integrated Micro LED chip technology.

[0080] In order to overcome this bottleneck, the preparation method of the LED device provided in this application first peels off the sapphire substrate on the blue LED chip on the InGaN-based blue LED chip by laser stripping to obtain the blue light source core, in preparation for the subsequent preparation of red and green light emitting chips. Among them, the laser stripping technology can use an ultraviolet excimer laser, the model can be COMPex 205, the laser wavelength is set to 248nm, the pulse width is 25ns, and the maximum frequency is 50Hz. In order to ensure that the laser energy of a single spot is more uniform, the laser is equipped with an optical path beam homogenization system to achieve large-area lossless laser stripping of Micro LED chips with a size of 34μm×58μm.

[0081] (2) Adding a red / green conversion layer

[0082] By high-precision inkjet printing technology or photolithography technology, red light quantum dot photoluminescent material is coated on the side and top surface of the blue light source core 31 to form a red light color conversion layer 11 to convert the blue light emitted by the blue light source core 31 into red light; in this step, a high-precision inkjet printer (IJP, Dimatix DMP 2831) can be used to print the quantum dot film layer. In order to ensure the best printing effect, a 1pl inkjet port is used to control the thickness of the quantum dot color conversion film layer, so that the thickness of the quantum dot film layer is guaranteed to be around 100nm-2000nm. In order to quickly dry the quantum dot ink and fix it on the surface of the blue light source core, the sample needs to be placed in a water-free and oxygen-free environment, and then irradiated and cured under an ultraviolet lamp with a wavelength of 365nm for 15 minutes to form a red light color conversion layer 11.

[0083] The preparation steps of the green light color conversion layer 21 are the same as those of the above method, except that the green light quantum dot photoluminescent material is coated on the side and top surface of the blue light source core. Specifically, the green light quantum dot photoluminescent material is coated on the side and top surface of the blue light source core by high-precision inkjet printing technology or photolithography technology to form a green light color conversion layer 21 to convert the blue light emitted by the blue light source core into green light. In this step, a high-precision inkjet printer (IJP, Dimatix DMP 2831) can also be used to print the quantum dot film layer. To ensure the best printing effect, a 1pl inkjet port is used to control the thickness of the quantum dot color conversion film layer, so that the thickness of the quantum dot film layer is guaranteed to be about 100nm-2000nm. In order to quickly dry the quantum dot ink and fix it on the surface of the blue light source core, the sample needs to be placed in an anhydrous and oxygen-free environment, and then irradiated and cured for 15 minutes under an ultraviolet lamp with a wavelength of 365nm to form a green light color conversion layer 21.

[0084] (3) Add red / green / blue filter layers

[0085] A filter layer that allows light of a specific wavelength to pass is deposited on the red light color conversion layer 11 and the green light color conversion layer 21, and on the surface of the blue light LED chip from which the sapphire substrate has not been stripped, to form a red light filter layer 12, a green light filter layer 22, and a blue light filter layer 32 respectively; the deposition process of the filter layer includes coating, exposure, development, and baking. Specifically, first, a layer of red photosensitive glue is coated on the red light color conversion layer 11, a layer of green photosensitive glue is coated on the green light color conversion layer 21, and a layer of blue photosensitive glue is coated on the surface of the blue light LED chip; then, a red filter layer, a green filter layer, and a blue filter layer corresponding to the pixel are formed through exposure, development, and baking.

[0086] (4) Adding a first graphene heat radiation layer 4

[0087] A first graphene thermal radiation layer 4 is formed on the surface of each filter layer by magnetron sputtering equipment or spraying method to improve the heat dissipation performance of each light-emitting chip. Among them, magnetron sputtering coating equipment is an advanced thin film deposition technology tool, which is widely used in semiconductors, optics, decoration and functional coatings. It bombards the graphene target material with high-energy particles enhanced by a magnetic field in a vacuum environment, so that the atoms or molecules of the graphene target material are sputtered out and deposited on the surface of the red filter layer, the green filter layer and the blue filter layer to form a uniform and dense graphite film, that is, the first graphene thermal radiation layer 4. The thickness range of the first graphene thermal radiation layer 4 should be controlled to be 2μm-5μm.

[0088] (5) Preparation of RGB sub-pixels

[0089] The red LED chip, green LED chip and blue LED chip coated with the first graphene thermal radiation layer 4 are transferred and installed on the substrate through the Micro LED mass transfer equipment to form a single RGB sub-pixel, and then encapsulated with packaging glue. After the curing temperature is 80°C-120°C and the curing time is 30 minutes-60 minutes, a packaging glue layer 5 is formed.

[0090] Since the characteristic size of Micro LED is less than 100μm, it is difficult for traditional transfer technology to meet the requirements in terms of transfer efficiency and transfer accuracy. Traditional transfer technology has physical limits on the size requirements of a single chip. The chip is too small to be transferred, and the transfer accuracy is difficult to meet. The robotic arm also has time limits in the process of chip transfer, and it is difficult to improve the transfer efficiency, which means that traditional transfer technology and equipment are no longer suitable for the Micro LED transfer process. In the face of the above technical challenges, in order to achieve fast and accurate transfer and reduce the pressure of subsequent maintenance, mass transfer technology came into being. Micro LED mass transfer technology has been proven to be an effective solution that can overcome the extreme requirements of assembling Micro LED chips. Micro LED mass transfer equipment uses laser transfer technology, using a specially shaped square spot, combined with high-speed galvanometer scanning, to achieve high-speed processing, transferring micron-level Micro LED chips one by one to the underlying substrate.

[0091] (6) Adding a second graphene heat radiation layer 6

[0092] A second graphene thermal radiation layer 6 is plated on the surface of the packaging glue layer 5 by magnetron sputtering equipment or spraying method, and the second graphene thermal radiation layer 6 forms a double-layer graphene thermal radiation structure with the first graphene thermal radiation layer 4. Among them, the magnetron sputtering coating equipment can adopt the same equipment in step (4). In a vacuum environment, high-energy particles enhanced by a magnetic field are used to bombard the graphene target material, so that the atoms or molecules of the graphene target material are sputtered out and deposited on the surface of the packaging glue layer 5 to form a uniform and dense graphite film, that is, the second graphene thermal radiation layer 6. The thickness range of the second graphene thermal radiation layer 6 should be controlled to be 2μm-5μm.

[0093] like Figures 9a to 9c As shown in the figure, it is a thermal imaging view of a traditional LED device. It can be seen that the heat distribution of a traditional LED device is centered on the light source core and radiates to the surrounding areas. The closer to the light source core, the higher the temperature, and the farther away from the light source core, the lower the temperature. Figures 10a to 10c As shown in the figure, it is a thermal imaging view of the LED device of the present application. It can be seen that under the action of the double-layer graphene thermal radiation structure, the heat distribution on the LED device is relatively uniform, and there is no obvious radiation distribution around the light source core, and the overall temperature of the LED device is lower than that of the traditional LED device. The following table shows the measured values ​​of the center temperature of each viewing angle of the traditional LED device and the LED device of the present application. It can be seen that the center temperature of the LED device of the present application at each viewing angle is about 2°C lower than the center temperature of each viewing angle of the traditional LED device.

[0094] Main viewing center temperature Side view center temperature Looking down at the center temperature Traditional LED devices 28.6℃ 29.3℃ 30.4℃ This application LED device 26.3℃ 27.5℃ 28.5℃

[0095] The present application also provides an LED display screen, including the LED device in the above embodiment, and also including components such as a display screen box and a control box. Specifically, the display screen box serves as a supporting frame for the LED display screen. The control box, as the intelligent center of the LED display screen, integrates functions such as image processing, color correction, brightness adjustment, and fault self-detection. It is responsible for receiving and processing high-definition video and image data from an external signal source. Since the LED display screen has the LED device in the above embodiment, it also has the advantages of the LED device in the above embodiment.

[0096] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. An LED device, characterized in that: include: A light-emitting component comprises a substrate, and a red light-emitting chip (1), a green light-emitting chip (2), and a blue light-emitting chip (3) arranged at intervals on the substrate; A first graphene heat radiation layer (4) is arranged on the outer layer of the red light emitting chip (1), the green light emitting chip (2) and the blue light emitting chip (3); A packaging adhesive layer (5) is arranged on the first graphene heat radiation layer (4) and the substrate; The second graphene heat radiation layer (6) is arranged on the packaging glue layer (5).

2. The LED device according to claim 1, characterized in that The thickness of the first graphene heat radiation layer (4) is in the range of 2 μm to 5 μm.

3. The LED device according to claim 1 or 2, characterized in that: The red light emitting chip (1) comprises a blue light emitting source core (31), a red light color conversion layer (11) arranged on the surface of the blue light emitting source core (31), and a red light filter layer (12) arranged on the surface of the red light color conversion layer (11).

4. The LED device according to claim 1 or 2, characterized in that: The green light emitting chip (2) comprises a blue light emitting source core (31), a green light color conversion layer (21) arranged on the surface of the blue light emitting source core (31), and a green light filter layer (22) arranged on the surface of the green light color conversion layer (21).

5. The LED device according to claim 1 or 2, characterized in that: The blue light emitting chip (3) comprises a blue light emitting source core (31) and a blue light filter layer (32) arranged on the surface of the blue light emitting source core (31).

6. A method for preparing an LED device, characterized in that: The steps include: S0: providing a plurality of blue light emitting chips (3), wherein the blue light emitting chips (3) comprise a blue light emitting source core (31) and a sapphire substrate arranged on the blue light emitting source core (31); S1: obtaining a blue light emitting source core (31), and removing the sapphire substrate of the blue light emitting chip (3) using a laser lift-off device to obtain the blue light emitting source core (31); S2: adding a red / green color conversion layer, and adding a red light color conversion layer (11) / a green light color conversion layer (21) on the side and top surface of the blue light source core (31); S3: adding red / green / blue filter layers, adding a red light filter layer (12) and a green light filter layer (22) on the surface of the red light color conversion layer (11) and the green light color conversion layer (21) respectively, taking the blue light emitting source core (31) described in S1, and adding a blue light filter layer (32) on the surface of the blue light emitting source core (31); S4: adding a first graphene heat radiation layer (4), and adding a first graphene heat radiation layer (4) on the surface of the red light filter layer (12) / the green light filter layer (22) / the blue light filter layer (32); S5: preparing RGB sub-pixels, combining the chips with the first graphene heat radiation layer (4) added in S4 into a light-emitting combination including a red light-emitting chip (1), a green light-emitting chip (2) and a blue light-emitting chip (3), transferring and installing the chips to a substrate, and then adding a packaging glue layer (5) on the surface; S6: Adding a second graphene heat radiation layer (6), adding a second graphene heat radiation layer (6) on the surface of the packaging glue layer (5).

7. The method for preparing an LED device according to claim 6, wherein: When adding a red / green conversion layer, an inkjet printer or photolithography equipment is used to coat the side and top surfaces of the blue light source core (31) with a red light quantum dot photoluminescent material to form a red light color conversion layer (11); and a green light quantum dot photoluminescent material is coated on the side and top surfaces of the blue light source core (31) to form a green light color conversion layer (21).

8. The method for preparing an LED device according to claim 7, characterized in that: The thickness of the red light color conversion layer (11) and the green light color conversion layer (21) are both in the range of 100 nm to 2000 nm.

9. The method for preparing an LED device according to claim 6, wherein: The red light filter layer (12) allows red light with a wavelength range of 620nm-640nm to pass through, the green light filter layer (22) allows green light with a wavelength range of 520nm-540nm to pass through, and the blue light filter layer (32) allows blue light with a wavelength range of 450nm-460nm to pass through.

10. An LED display screen, characterized in that: The LED device comprises the LED device as claimed in any one of claims 1 to 5.

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