Micro LED light emitting structure for digital vehicle lamp and preparation method thereof

Abstract

This application relates to the field of micro-LED display technology, and more particularly to a micro-LED light-emitting structure and fabrication method for digital automotive lights, comprising: a p-GaN layer, a light-emitting layer, an n-GaN layer, a phosphor layer, and an encapsulation dielectric layer sequentially arranged along the light-emitting direction; the phosphor layer is disposed on the light-emitting side of the n-GaN layer, and the phosphor layer has a lens array in the light-emitting direction, the lens array comprising multiple lens units arranged in an array and protruding in the light-emitting direction; the refractive indices N1 of the phosphor layer, N2 of the n-GaN layer, and N3 of the encapsulation dielectric layer satisfy: N2>N1>N3. Since the phosphor layer is located between the n-GaN layer and the encapsulation dielectric layer, a gradual transition of refractive index is formed between the n-GaN layer and the encapsulation dielectric layer, reducing interface reflection loss and increasing light emission brightness; at the same time, the lens array on the surface of the phosphor layer can also regulate the refraction of off-axis rays within the effective aperture, thereby improving light extraction efficiency and light emission collimation.

Description

Technical Field

[0001] This application relates to the field of micro-LED display technology, and in particular to a micro-LED light-emitting structure and its fabrication method for digital vehicle lights. Background Technology

[0002] Currently, Micro-LED, as an important light-emitting device for next-generation displays and micro-lighting, has shown significant application potential in fields such as micro-displays, automotive displays, near-eye displays, and highly directional lighting due to its advantages such as high brightness, low power consumption, fast response speed, long lifespan, and ease of high-density integration.

[0003] The prior art relates to a micro-LED light-emitting display device and its fabrication method. In the fabrication method of the micro-LED light-emitting display device, zirconium oxide is used as a protective layer for the micro-LED unit. Due to the high density of zirconium oxide, it can more effectively protect the micro-LED unit. By setting each micro-LED unit to have an upper surface, a lower surface, and an inclined side surface, the angle between the side surface and the lower surface of the micro-LED unit is 50-60 degrees. By optimizing the angle between the side surface and the lower surface of the micro-LED unit, the fabrication of the zirconium oxide protective layer and the first metal layer is facilitated, and the reflectivity of the side surface of the micro-LED unit is effectively improved, thereby improving the light extraction efficiency of the micro-LED unit.

[0004] However, the aforementioned and existing Micro-LEDs typically exhibit near-Lambertian emission characteristics during actual light extraction. A large amount of light generated inside the chip propagates outward at a large angle, resulting in insufficient energy concentration per unit area. At the same time, there are multiple refractive index abrupt interfaces between the semiconductor layer, transparent electrode layer, phosphor layer, encapsulation resin layer, and air. Due to the combined effect of interface refractive index mismatch and total internal reflection, some light will be reflected, folded back, and locally trapped inside the device, making it difficult to effectively couple to the external space. This limits the light extraction efficiency and makes it difficult to meet the requirements of high brightness directional light output and light collimation of digital automotive lights. Summary of the Invention

[0005] This application provides a micro-LED light-emitting structure and its fabrication method for digital vehicle lights, which can solve the problem that existing micro-LED light-emitting structures used in digital vehicle lights cannot meet the requirements of high brightness directional light emission and light emission collimation.

[0006] The technical solution of this application is as follows: A micro-LED light-emitting structure for digital vehicle lights, comprising: a p-GaN layer, a light-emitting layer, an n-GaN layer, a phosphor layer and an encapsulation dielectric layer arranged sequentially along the light-emitting direction; The phosphor layer is disposed on the light-emitting side of the n-GaN layer. The phosphor layer is provided with a lens array in the light-emitting direction. The lens array includes multiple lens units arranged in an array and protruding in the light-emitting direction. The lens units are used to deflect part of the off-axis light rays within the effective aperture toward the optical axis of the lens unit (411). The refractive indices N1 of the phosphor layer, N2 of the n-GaN layer, and N3 of the encapsulation medium layer satisfy the following condition: N2>N1>N3.

[0007] By adopting the above scheme, when the light generated by the light-emitting layer passes through the n-GaN layer and strikes the phosphor layer, the phosphor layer is located between the n-GaN layer and the encapsulation dielectric layer, and the refractive index satisfies N2>N1>N3. This creates a gradual transition in refractive index between the n-GaN layer and the encapsulation dielectric layer. The refractive index difference at the interface between the n-GaN layer and the phosphor layer is smaller than the refractive index difference directly between the n-GaN layer and the encapsulation dielectric layer. Therefore, Fresnel reflection at this interface can be reduced, thereby reducing interface reflection loss caused by abrupt changes in refractive index and increasing the probability of large-angle light entering the encapsulation dielectric layer, thus increasing... The light output brightness is improved. At the same time, the lens array on the surface of the phosphor layer can also regulate the refraction of light after passing through the phosphor layer, causing some off-axis light rays within the effective aperture to deflect towards the optical axis of the lens unit or the preset center direction. This improves both light extraction efficiency and light output collimation. The phosphor layer can not only convert the wavelength of light, but also build a refractive index transition model, reducing light loss. Furthermore, the lens array on its surface can deflect the light, improving the collimation of the light. This allows refractive index matching and light output direction regulation to be coordinated in the same functional layer.

[0008] In one embodiment of this application, the sagittal height of the plurality of lens units gradually increases along the direction from the center to the edge of the phosphor layer; The aperture of the plurality of lens units gradually decreases from the center to the edge of the phosphor layer.

[0009] By adopting the above scheme, since the light rays in the edge region of the phosphor layer usually have a larger emission angle, gradually increasing the sag of the lens unit along the direction from the center to the edge of the phosphor layer and gradually decreasing the aperture of the lens unit can give the lens unit in the edge region a relatively stronger refraction and deflection capability, thereby compensating for the light rays that deviate significantly from the vertical direction at the edge. At the same time, the lens unit in the central region maintains a larger aperture and a smaller sag, which helps to reduce the excessive deflection of paraxial light rays. Therefore, the lens array can be zoned and controlled according to the difference in the emission angle at different positions, so that the light rays in the central region and the edge region tend to be emitted vertically, thereby further improving the overall emission uniformity and collimation.

[0010] In one embodiment of this application, a protrusion array is further included. The protrusion array is disposed on the side of the n-GaN layer near the phosphor layer. The protrusion array includes a plurality of transparent protrusions arranged in an array. A dot array is disposed on the side of the phosphor layer near the n-GaN layer. The dot array includes a plurality of dots that correspond one-to-one with the transparent protrusions and have matching shapes.

[0011] By adopting the above scheme, the protrusion array is set on the side of the n-GaN layer close to the phosphor layer, so that an optical interface with surface undulation is formed between the n-GaN layer and the phosphor layer. When light passes through this interface, the incident angle changes, thereby reducing the probability of total internal reflection of some large-angle light rays at the planar interface and increasing the chance of them entering the phosphor layer. At the same time, since the transparent protrusions in the protrusion array are embedded in the phosphor layer, they can limit and anchor the phosphor layer during the phosphor layer forming and curing process, reducing the impact of the lateral flow of the phosphor layer on the forming accuracy of the lens array.

[0012] In one embodiment of this application, the phosphor layer comprises: A first fluorescent layer is disposed on the light-emitting side of the n-GaN layer, and the lens array is disposed on the surface of the first fluorescent layer opposite to the n-GaN layer. A second fluorescent layer is disposed on the lens array surface of the first fluorescent layer. A recessed array is formed on the side of the second fluorescent layer close to the first fluorescent layer, and the shape of the recessed array matches that of the lens array. A flat light-emitting surface is provided on the other side.

[0013] By adopting the above scheme, the first fluorescent layer is disposed on the light-emitting side of the n-GaN layer and carries the lens array, so that the light can be directionally controlled by the lens array before entering the second fluorescent layer; the concave array of the second fluorescent layer matches the shape of the lens array, which can fill the undulating structure of the surface of the first fluorescent layer, so that the first fluorescent layer and the second fluorescent layer maintain continuous adhesion, reducing scattering and local light loss caused by gaps or interface discontinuities; at the same time, the side of the second fluorescent layer away from the first fluorescent layer forms a flat light-emitting surface, which is beneficial to the formation of the subsequent encapsulation dielectric layer and reduces the morphological fluctuation of the external encapsulation interface.

[0014] In one embodiment of this application, the first fluorescent layer includes a first transparent substrate, the second fluorescent layer includes a second transparent substrate, and the refractive index N11 of the first transparent substrate and the refractive index N12 of the second transparent substrate satisfy: N2>N11>N12>N3.

[0015] By adopting the above scheme, the refractive index N11 of the first transparent substrate is greater than the refractive index N12 of the second transparent substrate, forming an internal interface between the first and second fluorescent layers that transitions from a high refractive index to a low refractive index. This internal interface, combined with the lens array on the surface of the first fluorescent layer, can effectively refract light under the condition of refractive index difference, enabling the lens array to have actual beam deflection capability. At the same time, the refractive index of the second transparent substrate is lower than that of the first transparent substrate, which is beneficial to form a stepwise refractive index change as light travels from the n-GaN layer through the first fluorescent layer and the second fluorescent layer and then into the encapsulation medium layer. This reduces the reflection loss caused by the abrupt change in refractive index at a single interface, and also allows the refractive index of the first transparent substrate to be closer to that of the n-GaN layer, reducing light loss and thus improving the light extraction rate. Therefore, the refractive index difference is not only used to achieve refractive control of the lens array, but also allows the light to undergo a further refractive index transition in the light-emitting direction, thereby further improving the light extraction rate.

[0016] In one embodiment of this application, the first transparent substrate and the second transparent substrate are both filled with phosphor particles by mass fraction. The phosphor particle concentration K1 in the first transparent substrate and the phosphor particle concentration K2 in the second transparent substrate satisfy: K1>K2. The thickness of the second fluorescent layer is less than the thickness of the first fluorescent layer.

[0017] By adopting the above scheme, the phosphor particle concentration K1 in the first transparent substrate is greater than the phosphor particle concentration K2 in the second transparent substrate. This allows the first phosphor layer, which is closer to the n-GaN layer, to undertake the main wavelength conversion function, which helps to shorten the ineffective propagation path of the excitation light after entering the phosphor layer. At the same time, since the refractive index of the first phosphor layer is closer to that of the n-GaN layer, the first phosphor layer can improve the absorption and utilization of the excitation light by the phosphor particles while improving the light extraction rate. Meanwhile, the second phosphor layer uses a lower phosphor particle concentration and has a thickness smaller than that of the first phosphor layer, which can reduce the multiple scattering and reabsorption loss of light in the planarization capping layer, while maintaining its filling and planarization functions for the lens array. Therefore, the differentiated setting of phosphor particle concentration and thickness in the phosphor layer can take into account color conversion efficiency, light loss control, and encapsulation interface flatness.

[0018] In one embodiment of this application, a reflective layer is further included, disposed on the side of the p-GaN layer opposite to the light-emitting layer, the reflective layer being configured to reflect light incident on the p-GaN layer back to the light-emitting side where the n-GaN layer is located.

[0019] By adopting the above scheme, the light generated by the light-emitting layer and directed towards the p-GaN layer can be reflected by the reflective layer and redirected back to the light-emitting side where the light-emitting layer and n-GaN layer are located, reducing the loss caused by the absorption of back-propagating light by the electrodes, substrate or packaging structure, thereby further ensuring the light extraction rate.

[0020] The second objective of this application is to provide a method for fabricating a micro-LED light-emitting structure for digital vehicle lights.

[0021] The technical solution is as follows: A method for fabricating a micro-LED light-emitting structure for digital vehicle lights, comprising the following steps: S1. Provide an epitaxial wafer, the epitaxial wafer comprising a p-GaN layer, a light-emitting layer and an n-GaN layer sequentially disposed along the light-emitting direction; S2. The light-emitting side surface of the n-GaN layer is cleaned and surface-treated, and a phosphor layer is coated on it. S3. Set a metal template, the metal template having an inverted lens array structure inside, align the metal template with the phosphor layer and press them together; S4. Maintain the pressed state of the metal template and cure the phosphor layer. After curing, remove the metal template to form a lens array from the phosphor layer. S5. An encapsulation dielectric layer is formed on the side of the phosphor layer opposite to the n-GaN layer.

[0022] By adopting the above scheme, a phosphor layer is directly coated on the light-emitting side of the n-GaN layer, and the phosphor layer is pressed and molded using a metal template with a lens array inversion structure. At the same time, the phosphor layer can perform wavelength conversion while a lens array is formed on the surface of the phosphor layer. This allows the phosphor layer molding, lens array molding, and light-emitting side optical control to be integrated into the same process. It also enables the fabricated micro-LED light-emitting structure to collimate and adjust the off-axis light within the effective aperture.

[0023] In one embodiment of this application, when the micro-LED light-emitting structure includes a protrusion array (6), before step S2, the method further includes: forming a protrusion array with a refractive index higher than that of the phosphor layer on the light-emitting side of the n-GaN layer by imprinting and curing. In step S2, the phosphor layer is formed by dispensing, spin coating, scraping or spraying, and covers the protrusion array.

[0024] By adopting the above scheme, the protrusion array is formed on the light-emitting side of the n-GaN layer by imprinting and curing, without the need to etch the n-GaN layer itself, which helps to reduce the risk of surface defects and damage caused by plasma etching. At the same time, the refractive index of the protrusion array is higher than that of the phosphor layer, so when it is located between the n-GaN layer and the phosphor layer, it can participate in the interface refractive index regulation as an intermediate optical structure. It can also change the local normal direction of the light incident interface by array undulation, thereby increasing the probability of large-angle light entering the phosphor layer. After the phosphor layer covers the protrusion array by dispensing, spin coating, scraping or spraying, the protrusion array can also form a mechanical limit on the uncured phosphor layer, which helps to suppress the lateral flow of the phosphor layer during the subsequent imprinting of the lens array.

[0025] When the phosphor layer includes a first phosphor layer and a second phosphor layer, step S2 includes: coating the first phosphor layer on the light-emitting side of the n-GaN layer; Step S3 includes: aligning and pressing the metal template with the first fluorescent layer; Step S4 includes: curing the first fluorescent layer and removing the metal template to form a lens array, coating the second fluorescent layer onto the lens array and curing it to form a flat light-emitting surface.

[0026] By adopting the above scheme, a first fluorescent layer is first coated on the light-emitting side of the n-GaN layer, and a lens array is formed by pressing and curing with a metal template. This allows the lens array to be stably formed on the surface of the first fluorescent layer. Subsequently, a second fluorescent layer is coated on the lens array, filling the surface undulations of the lens array and curing to form a flat light-emitting surface. This can improve the flatness of the outermost light-emitting surface while retaining the refractive light-tuning effect of the interface between the first and second fluorescent layers. At the same time, this preparation sequence allows the optical control function of the lens array and the planarization function of the second fluorescent layer to be realized step by step, reducing the mutual disturbance between the two in the same uncured system. This is beneficial to improving the morphological stability of the lens array and the consistency of the encapsulation interface.

[0027] In summary, this application includes at least one of the following beneficial technical effects: The phosphor layer is disposed on the light-emitting side of the n-GaN layer, and the refractive indices N1 of the phosphor layer, N2 of the n-GaN layer, and N3 of the encapsulation medium layer satisfy N2>N1>N3, creating a gradual transition in refractive index between the n-GaN layer and the encapsulation medium layer. This reduces reflection loss at the light-emitting interface and increases the probability of large-angle light propagating outwards. Simultaneously, a lens array is disposed on the side of the phosphor layer facing away from the n-GaN layer, causing off-axis light rays passing through the effective aperture of the phosphor layer to deflect in a direction perpendicular to the phosphor layer surface, thereby improving light collimation. Thus, the phosphor layer simultaneously performs wavelength conversion, refractive index transition, and lens array support functions, thereby meeting the requirements of digital automotive lights for high-brightness directional light emission and collimation.

[0028] This application provides a protrusion array on the side of the n-GaN layer near the phosphor layer, and the phosphor layer covers the protrusion array, forming an undulating optical interface between the n-GaN layer and the phosphor layer. This undulating interface can change the local normal direction of the light incident interface, reducing the probability of total internal reflection of some large-angle light rays at the interface between the n-GaN layer and the phosphor layer. Furthermore, after the protrusion array is embedded in the phosphor layer, it can play a mechanical limiting and anchoring role during the phosphor layer imprinting process, which helps to suppress the lateral flow of the phosphor layer and maintain the forming accuracy of the lens array.

[0029] This application sets the phosphor layer as a first phosphor layer and a second phosphor layer. The first phosphor layer is close to the n-GaN layer and supports the lens array, while the second phosphor layer covers the lens array and forms a flat light-emitting surface. The first phosphor layer can undertake the main wavelength conversion and lens array shaping functions, while the second phosphor layer fills and flattens the surface undulations of the lens array, which facilitates the formation of a stable encapsulation medium layer. At the same time, since the refractive index N11 of the first transparent substrate is greater than the refractive index N12 of the second transparent substrate, the lens array interface between the first and second phosphor layers can generate effective refraction modulation, further improving the light extraction rate. In addition, the phosphor particle concentration K1 in the first phosphor layer is greater than the phosphor particle concentration K2 in the second phosphor layer, and the thickness of the second phosphor layer is less than the thickness of the first phosphor layer. This allows more light to undergo more scattering and conversion in the first phosphor layer with a higher phosphor particle concentration while ensuring a high light extraction rate. The converted light then enters the second phosphor layer with a lower phosphor particle concentration, thereby ensuring that the light after wavelength conversion and incident angle modulation is stably emitted in the second phosphor layer. This allows the first and second phosphor layers to work synergistically in wavelength conversion, beam modulation, scattering loss control, and flat encapsulation. Attached Figure Description

[0030] Figure 1 This is a cross-sectional view of a micro-LED light-emitting structure for digital vehicle lights provided in the first embodiment of this application; Figure 2 This is a schematic diagram of the optical path when the off-axis light rays are deflected within the effective aperture of a micro-LED light-emitting structure for digital vehicle lights, provided in the first embodiment of this application; Figure 3 This is a cross-sectional view of a micro-LED light-emitting structure for digital vehicle lights provided in the second embodiment of this application; Figure 4 This is a cross-sectional schematic diagram of the phosphor layer of a micro-LED light-emitting structure for digital vehicle lights provided in the second embodiment of this application; Figure 5This is a cross-sectional schematic diagram of an n-GaN layer of a micro-LED light-emitting structure for digital vehicle lights provided in the second embodiment of this application; Figure 6 This is a cross-sectional view of a micro-LED light-emitting structure for digital vehicle lights provided in the third embodiment of this application; Figure 7 This is a schematic flowchart of a method for fabricating a micro-LED light-emitting structure for digital vehicle lights, provided in the first embodiment of this application. Figure 8 This is a flowchart illustrating a method for fabricating a micro-LED light-emitting structure for digital vehicle lights, as provided in the first embodiment of this application.

[0031] Explanation of reference numerals in the attached figures: 1. p-GaN layer; 2. Light-emitting layer; 3. n-GaN layer; 4. Phosphor layer; 41. Lens array; 411. Lens unit; 42. First phosphor layer; 421. First transparent substrate; 43. Second phosphor layer; 431. Recessed array; 432. Flat light-emitting surface; 433. Second transparent substrate; 44. Dot array; 441. Dot; 5. Encapsulation dielectric layer; 6. Raised array; 61. Transparent raised area; 7. Reflective layer; 8. Metal template; 9. Transparent cover plate. Detailed Implementation

[0032] The following is in conjunction with the appendix Figures 1-8 This application provides a further detailed description of a microLED light-emitting structure and its fabrication method for digital vehicle lights.

[0033] The micro-LED light-emitting structure for digital vehicle lights provided in this application embodiment includes: a p-GaN layer 1, a light-emitting layer 2, an n-GaN layer 3, a phosphor layer 4, and an encapsulation dielectric layer 5 arranged sequentially along the light-emitting direction. Example 1

[0034] Please see Figure 1 and Figure 2 Phosphor layer 4 is disposed on the light-emitting side of n-GaN layer 3. Phosphor layer 4 is provided with lens array 41 in the light-emitting direction. Lens array 41 includes multiple lens units 411 arranged in an array and protruding in the light-emitting direction. The lens units 411 are used to deflect part of the off-axis light rays within the effective aperture toward the optical axis of the lens unit 411. The refractive index N1 of phosphor layer 4, the refractive index N2 of n-GaN layer 3 and the refractive index N3 of encapsulation dielectric layer 5 satisfy: N2>N1>N3.

[0035] In this embodiment, the light-emitting layer 2 can be a GaN-based multi-quantum-well light-emitting layer, the n-GaN layer 3 serves as the main light-emitting side, and the phosphor layer 4 is formed by mixing phosphor particles and a high-refractive-index transparent optical adhesive. The high-refractive-index transparent optical adhesive can be UV-cured or UV-Vis-cured, and its refractive index after curing can be 1.65 to 1.75, for example, 1.65, 1.70, or 1.75. The encapsulation medium layer 5 can be made of transparent silicone, transparent epoxy resin or other transparent resins used for automotive lamp encapsulation, and its refractive index is usually lower than that of the phosphor layer 4, for example, it can be 1.40 to 1.55.

[0036] It should be noted that the refractive index of GaN material in the visible light band is usually higher than that of phosphor layer 4. Therefore, it can satisfy the refractive index relationship of N2>N1>N3. When light enters phosphor layer 4 from n-GaN layer 3 and then enters encapsulation medium layer 5, the refractive index gradually transitions from N2 to N1 and then to N3. Compared with the structure in which n-GaN layer 3 is in direct contact with low refractive index encapsulation medium layer 5, this can reduce the degree of refractive index change at a single interface, reduce Fresnel reflection loss, and increase the probability of some large-angle light entering encapsulation medium layer 5.

[0037] It should be noted that, for lens unit 411, the judgment of its control over light should not be based solely on whether the light is close to or far from the local normal at a single interface, but should be made in combination with the local normal direction of the curved interface and the overall optical axis direction.

[0038] like Figure 2 As shown, in this embodiment, the collimation of light by the lens unit is achieved based on the positive optical power generated by the overall curved surface morphology of the lens unit and the refractive index difference. Since the refractive index N1 of the phosphor layer 4 is greater than the refractive index N3 of the encapsulation medium layer 5, and the lens unit 411 bulges in the light-emitting direction, a convex curved refractive interface is formed between the phosphor layer 4 and the encapsulation medium layer 5. For off-axis rays located within the effective aperture of the lens unit 411, when they are incident on the curved refractive interface at the edge region of the lens unit 411, the local normal of the curved interface is tilted relative to the optical axis of the lens unit 411. When light enters the low-refractive-index encapsulation medium layer 5 from the high-refractive-index phosphor layer 4, although it is refracted away from the local normal, the tilt of the local normal itself reduces the angle between the refracted propagation direction and the optical axis of the lens unit 411, resulting in a deflection towards the optical axis or a predetermined center direction.

[0039] Therefore, the lens array 41 can compress the angular distribution of some of the effective emitted light rays and improve the concentration of the emitted light direction. Thus, the phosphor layer 4 is not only used for fluorescence conversion, but also serves as a refractive index transition layer and a carrier layer for the lens array 41, so that the improvement of light extraction efficiency and the improvement of light collimation can be achieved in the same optical path.

[0040] It should be noted that the optical axis of the lens unit 411 refers to the axis that passes through the geometric center or vertex of the lens unit 411 and extends along the light emission direction; when the lens unit 411 is a spherical, hemispherical or parabolic lens unit, the optical axis may be the axis that passes through the vertex of the lens unit 411 and is perpendicular to the reference plane of the phosphor layer 4.

[0041] The effective aperture refers to the light-transmitting area in the lens unit 411 that can participate in predetermined refraction control and deflect light towards the optical axis.

[0042] The effective aperture can be the light-transmitting area corresponding to the aperture D of the lens unit 411, or it can be the light-transmitting area after deducting the rounded corner area of ​​the lens unit 411, the transition area between adjacent lens units 411, the blocking area, or the area prone to total internal reflection.

[0043] The off-axis ray refers to the ray whose incident position deviates from the optical axis of the lens unit 411 and / or whose propagation direction has an angle with respect to the optical axis of the lens unit 411. After the off-axis ray is refracted by the lens unit 411, its angle with respect to the optical axis of the lens unit 411 decreases, which can be considered as its deflection toward the optical axis of the lens unit 411.

[0044] The lens unit 411 can be one of the following shapes: spherical, hemispherical, parabolic, cylindrical, or frustum-shaped, preferably a spherical lens unit 411.

[0045] The height of the lens unit 411 can be from 10μm to 20μm, for example, 10μm, 15μm or 20μm; the aperture of the lens unit 411 can be determined according to the size of the light-emitting area of ​​the microLED chip and the arrangement density of the lens array 41, preferably from 20μm to 80μm, for example, 20μm, 50μm or 80μm; the arrangement period of adjacent lens units 411 can be equal to or slightly larger than the aperture of the lens unit 411, for example, from 25μm to 100μm.

[0046] It should be noted that for the spherical lens unit 411, its radius of curvature R can be determined according to the formula R=(D² / 4+h²) / (2h), where D is the aperture of the lens unit 411 and h is the height of the lens unit 411. The lens unit 411 forms a positive optical power curved refractive interface between the phosphor layer 4 and the encapsulation medium layer 5. In specific design, the aperture D, height h and radius of curvature R of the lens unit 411 can be determined according to the size of the Micro-LED light-emitting area, the thickness of the phosphor layer, the refractive index of the encapsulation medium and the standard angle of the target.

[0047] Under paraxial conditions, the equivalent focal length of the lens unit 411 can increase with the increase of the radius of curvature R and decrease with the increase of the refractive index difference N1-N3. Therefore, by increasing the sag of the lens unit 411 in the edge region, reducing its aperture or radius of curvature, the refraction and focusing ability of the edge region for large-angle light rays can be improved; by reducing the sag of the lens unit 411 in the center region or increasing its aperture, the excessive deflection of paraxial light rays can be reduced. Thus, the lens array 41 can perform zoned collimation control of light rays in different regions.

[0048] It also includes a reflective layer 7, which is disposed on the other side of the p-GaN layer 1 away from the light-emitting layer 2. The reflective layer 7 is configured to reflect the light incident on the p-GaN layer 1 to the light-emitting side where the n-GaN layer 3 is located.

[0049] In this embodiment, the reflective layer 7 can be a metal reflective layer, a dielectric distributed Bragg reflective layer, or a composite reflective layer formed by combining a metal reflective layer and a dielectric reflective layer. The metal reflective layer can be Ag, Al, Ni / Ag, Ti / Al, or other metal systems suitable for GaN-based LED electrodes and reflective structures. Among them, Ag has a high reflectivity in the visible light band and is suitable as a reflective metal for blue or white light micro-LEDs.

[0050] In addition, it should be noted that, in order to improve the stability and reliability of the electrical connection between the reflective layer 7 and the p-GaN layer 1, the reflective layer 7 may also include an ohmic contact layer, a diffusion barrier layer or a protective layer, such as Ni, Ti, Pt, Cr, ITO or a combination thereof. The specific layer system can be determined according to the contact resistance and packaging reliability requirements of the p-GaN layer 1.

[0051] In this embodiment, the light emitted by the light-emitting layer 2 does not only propagate along the direction of the n-GaN layer 3, but propagates in multiple directions. If the light rays that strike the p-GaN layer 1 are not utilized, they are easily absorbed by the metal electrode, substrate, or packaging structure. By setting a reflective layer 7 on the other side of the p-GaN layer 1 away from the light-emitting layer 2, the light rays that strike the p-GaN layer 1 can be reflected back to the direction where the light-emitting layer 2 and the n-GaN layer 3 are located, so that this part of the light rays can re-enter the phosphor layer 4 and the lens array 41 on the light-emitting side to control the path. Example 2

[0052] like Figure 3 , Figure 4 and Figure 5 As shown, the structure of Example 2 is basically the same as that of Example 1, except that: The sagittal height of the multiple lens units 411 gradually increases from the center to the edge of the phosphor layer 4; The aperture of the multiple lens units 411 gradually decreases from the center to the edge of the phosphor layer 4.

[0053] In this embodiment, the lens array 41 can be divided into multiple concentric regions or multiple partitioned regions from the center to the edge of the micro-LED light-emitting area. The lens units 411 in each partitioned region have the same or similar structural parameters, and the lens units 411 in different partitioned regions have different sagittal heights and apertures. The lens units 411 near the center of the phosphor layer 4 can be set to a smaller sagittal height and a larger aperture, for example, a sagittal height of 10μm to 13μm and an aperture of 60μm to 80μm; the lens units 411 in the middle region can be set to a medium sagittal height and a medium aperture, for example, a sagittal height of 13μm to 17μm and an aperture of 40μm to 60μm; the lens units 411 near the edge of the phosphor layer 4 can be set to a larger sagittal height and a smaller aperture, for example, a sagittal height of 17μm to 20μm and an aperture of 20μm to 40μm. The above endpoint values ​​and intermediate values ​​can be adjusted according to the chip size, pixel pitch, refractive index of the encapsulation medium, and target light-emitting angle.

[0054] Since the light rays at the edge of the light-emitting area of ​​a micro-LED typically have a larger lateral propagation component and a larger emission angle, when a lens unit 411 with a larger sag and a smaller aperture is set in the edge area, its curvature is usually larger, and its ability to refract and deflect light rays is stronger, which can concentrate light rays that deviate significantly from the normal direction at the edge. Meanwhile, the light rays in the central area are relatively close to the normal direction, and using a lens unit 411 with a smaller sag and a larger aperture can avoid excessive deflection of paraxial light rays.

[0055] Therefore, the lens array 41 performs zone compensation based on the difference in light output angle in different regions, so that the light from the central region and the edge region tends to be emitted perpendicularly.

[0056] It also includes a protrusion array 6, which is disposed on the side of the n-GaN layer 3 near the phosphor layer 4. The protrusion array 6 includes a plurality of transparent protrusions 61 arranged in an array. The phosphor layer 4 is provided with a dot array 44 on the side near the n-GaN layer 3. The dot array 44 includes a plurality of dots 441 that correspond one-to-one with the transparent protrusions 61 and have matching shapes.

[0057] In this embodiment, the protrusion array 6 can be formed of a transparent high refractive index material. The refractive index of the transparent high refractive index material is higher than that of the phosphor layer 4. Preferably, the refractive index can be 1.75 to 2.10, for example, 1.75, 1.90 or 2.10. The transparent high refractive index material can be a high refractive index optical resin, a transparent composite resin containing nano-zirconia or nano-titanium dioxide, a transparent inorganic oxide material or other transparent materials that can be imprinted and cured.

[0058] In order to avoid etching damage to the n-GaN layer 3, the bump array 6 is preferably formed on the light-emitting side of the n-GaN layer 3 by imprinting and curing, rather than by dry etching of the n-GaN layer 3 body.

[0059] The transparent protrusion 61 can be a conical protrusion, a cone-shaped protrusion, a pyramidal protrusion, a frustum-shaped protrusion, a hemispherical protrusion, or other transparent protrusions 61 capable of forming an undulating interface. Preferably, the transparent protrusion 61 is a conical or near-conical structure, with a height of 0.5 μm to 5 μm, for example, 0.5 μm, 2 μm, or 5 μm; a bottom width of 0.5 μm to 10 μm, for example, 0.5 μm, 5 μm, or 10 μm; and an arrangement period of 1 μm to 20 μm, for example, 1 μm, 10 μm, or 20 μm. The specific dimensions of the transparent protrusion 61 can be selected according to the allowable process window on the surface of the n-GaN layer 3, the thickness of the phosphor layer 4, and the scattering degree of the target interface, and therefore will not be elaborated here. Example 3

[0060] like Figure 6 As shown, the structure of Example 3 is basically the same as that of Example 2, except that: The phosphor layer 4 includes a first phosphor layer 42 and a second phosphor layer 43. The first phosphor layer 42 is disposed on the light-emitting side of the n-GaN layer 3, and the lens array 41 is disposed on the side surface of the first phosphor layer 42 away from the n-GaN layer 3. The second phosphor layer 43 is disposed on the surface of the lens array 41 of the first phosphor layer 42. A recessed array 431 is formed on the side of the second phosphor layer 43 close to the first phosphor layer 42. The shape of the recessed array 431 matches that of the lens array 41. A flat light-emitting surface 432 is provided on the other side.

[0061] In this embodiment, the first fluorescent layer 42 is disposed close to the n-GaN layer 3 and is used to undertake the main wavelength conversion function. A lens array 41 can be formed on the side of the first fluorescent layer 42 away from the n-GaN layer 3 by imprinting with a metal template 8. The second fluorescent layer 43 covers the surface of the lens array 41 of the first fluorescent layer 42. The side of the second fluorescent layer 43 close to the first fluorescent layer 42 forms a recessed array 431 due to the surface undulation of the lens array 41. The shape of the recessed array 431 matches that of the lens array 41.

[0062] It should be noted that when the phosphor layer 4 includes a first phosphor layer 42 and a second phosphor layer 43, the curved refractive interface is formed between the first phosphor layer 42 and the second phosphor layer 43, and the refraction of off-axis light is controlled by the refractive index difference between the first transparent substrate 421 and the second transparent substrate 433.

[0063] The thickness of the first fluorescent layer 42 can be determined according to the particle size of the phosphor, the target color coordinates, and the excitation light absorption requirements, and is preferably 20μm to 100μm, for example, 20μm, 60μm or 100μm; the second fluorescent layer 43 is mainly used to fill the undulations of the lens array 41 and form a flat light-emitting surface 432, and its thickness can be 5μm to 50μm, for example, 5μm, 25μm or 50μm, and its thickness is less than that of the first fluorescent layer 42. The flat light-emitting surface 432 of the second fluorescent layer 43 is convenient for subsequent coating or potting of the encapsulation medium layer 5, and can reduce the encapsulation thickness unevenness caused by the undulation of the outer surface.

[0064] The lens array 41 interface between the first fluorescent layer 42 and the second fluorescent layer 43 retains the curved surface morphology of the lens. Therefore, when light passes through this internal interface, it can be refracted and modulated by the lens array 41. At the same time, the second fluorescent layer 43 covers and flattens the lens array 41, which can reduce the air gap, local insufficiency, or interface discontinuity that may occur when the external encapsulation medium layer 5 is in direct contact with the lens array 41. Thus, the first fluorescent layer 42 undertakes the main light conversion and lens shaping functions, while the second fluorescent layer 43 undertakes the functions of filling, flattening, and auxiliary light conversion. The two form a division of labor in terms of structure and function.

[0065] The first fluorescent layer 42 includes a first transparent substrate 421, and the second fluorescent layer 43 includes a second transparent substrate 433. The refractive index N11 of the first transparent substrate 421 and the refractive index N12 of the second transparent substrate 433 satisfy: N2>N11>N12>N3.

[0066] In this embodiment, the first transparent substrate 421 can be made of high-refractive-index UV-curable or UV-Vis-curable optical adhesive, preferably a high-refractive-index optical adhesive or a transparent optical adhesive with a refractive index close to that of the substrate. Its refractive index N11 after curing can be 1.65 to 1.75, for example, 1.65, 1.70 or 1.75. The second transparent substrate 433 can be made of silicone, epoxy resin or low-refractive-index optical adhesive with relatively low refractive index and good light transmittance. Its refractive index N12 can be 1.45 to 1.63, for example, 1.45, 1.55 or 1.63, and satisfies N2>N11>N12>N3.

[0067] When there is a refractive index difference between the first transparent substrate 421 and the second transparent substrate 433, the lens array 41 disposed at the interface between the two can generate effective refraction control. If the refractive indices of the first transparent substrate 421 and the second transparent substrate 433 are exactly the same, the refraction effect of the lens array 41 interface will be significantly weakened. Therefore, making N2>N11>N12>N3 can ensure that the lens array 41 plays a beam deflection role as an internal refractive interface. At the same time, the first transparent substrate 421 is close to the n-GaN layer 3 and has a higher refractive index, which is beneficial to reduce the refractive index abrupt change between the n-GaN layer 3 and the phosphor layer 4. The second transparent substrate 433 is located between the first transparent substrate 421 and the encapsulation medium layer 5 and has a lower refractive index, which is beneficial to make the light form a high-to-low refractive index transition along the light output direction.

[0068] By mass fraction, both the first transparent substrate 421 and the second transparent substrate 433 are filled with phosphor particles. The phosphor particle concentration K1 in the first transparent substrate 421 and the phosphor particle concentration K2 in the second transparent substrate 433 satisfy: K1>K2. The thickness of the second fluorescent layer 43 is less than the thickness of the first fluorescent layer 42.

[0069] In this embodiment, the phosphor particles can be yellow phosphor, green phosphor, red phosphor, or combinations thereof suitable for blue light excitation of white light or specific color temperature automotive lamp light sources, such as YAG system phosphor, nitride red phosphor, silicate phosphor, or other automotive lamp phosphor systems.

[0070] In addition, the average particle size of phosphor particles can be determined according to the phosphor type and coating process, and can usually be selected from 1μm to 20μm, for example, 1μm, 10μm or 20μm. In order to balance the uniformity of dispersion and the ability to be printed, phosphor particles should be surface treated or reduced by dispersants, vacuum degassing or other methods to reduce agglomeration and bubbles.

[0071] The concentration of phosphor particles K1 in the first transparent substrate 421 is greater than the concentration of phosphor particles K2 in the second transparent substrate 433. Specifically, in terms of mass fraction, K1 can be 10wt% to 50wt%, for example, 10wt%, 30wt% or 50wt%; K2 can be 1wt% to 20wt%, for example, 1wt%, 10wt% or 20wt%. When there is an overlap between the ranges of K1 and K2, K1 should be greater than K2.

[0072] The specific concentrations of K1 and K2 should be determined based on the target color coordinates, the wavelength of the blue light chip, the phosphor conversion efficiency, the thickness of the phosphor layer 4, and the color temperature requirements of the white light of the vehicle headlight. The first phosphor layer 42 is close to the n-GaN layer 3 and has a higher phosphor particle concentration, which can allow the excitation light to be absorbed and converted earlier, reducing the ineffective propagation path of the excitation light in the phosphor layer 4. The second phosphor layer 43 uses a lower phosphor particle concentration and is thinner than the first phosphor layer 42, which can reduce the multiple scattering and reabsorption of light in the planarization capping layer, while still allowing for fine-tuning of the color coordinates.

[0073] When the thickness of the first fluorescent layer 42 is 20μm, 60μm or 100μm, the thickness of the second fluorescent layer 43 can be selected accordingly as 5μm, 20μm or 50μm. However, it should be ensured that the second fluorescent layer 43 can cover the highest point of the lens array 41 and form a continuous and flat light-emitting surface 432. If the second fluorescent layer 43 is too thin, it may not be able to completely fill the undulations of the lens array 41. If it is too thick, it may increase scattering and reabsorption losses. Therefore, it should be determined in combination with the sag of the lens unit 411, the particle size of the phosphor particles and the coating leveling performance.

[0074] The second objective of this application is to provide a method for fabricating a micro-LED light-emitting structure for digital vehicle lights.

[0075] like Figure 7 and Figure 8 As shown, the technical solution is as follows: A method for fabricating a micro-LED light-emitting structure for digital vehicle lights, comprising the following steps: S1. Provide an epitaxial wafer, the epitaxial wafer comprising a p-GaN layer 1, a light-emitting layer 2 and an n-GaN layer 3 arranged sequentially along the light-emitting direction; S2. The light-emitting side surface of the n-GaN layer 3 is cleaned and surface-treated, and then coated with phosphor layer 4. S3. Set up a metal template 8. The metal template 8 has a lens array inversion structure inside. Align the metal template 8 with the phosphor layer 4 and press them together. S4. Maintain the pressed state of the metal template 8 and cure the phosphor layer 4. After curing, remove the metal template 8 to form a lens array 41 from the phosphor layer 4. S5. An encapsulation dielectric layer 5 is formed on the side of the phosphor layer 4 opposite to the n-GaN layer 3.

[0076] In this embodiment, step S6 may be included after step S5; In step S6, the transparent cover plate 9 is placed on the side of the encapsulation medium layer 5 away from the phosphor layer 4, and the transparent cover plate 9 is bonded to the encapsulation medium layer 5; then the encapsulation medium layer 5 is cured so that the transparent cover plate 9, the encapsulation medium layer 5 and the phosphor layer 4 form an integrated encapsulation structure.

[0077] In this embodiment, the epitaxial wafer in step S1 can be a GaN-based Micro-LED epitaxial wafer. In step S2, the light-emitting side surface of the n-GaN layer 3 is cleaned and surface-treated, which may include one or more of the following: organic solvent cleaning, deionized water cleaning, nitrogen drying, oxygen plasma treatment, ultraviolet ozone treatment, or silane coupling agent treatment, to remove surface contaminants and improve the adhesion stability between the phosphor layer 4 and the n-GaN layer 3. The surface treatment intensity should be controlled within a range that does not damage the n-GaN layer 3 and does not affect the electrical performance of the chip.

[0078] Meanwhile, the phosphor layer 4 can be formed by dispensing, spin coating, blade coating, or spraying. For single or small numbers of chips, dispensing can be used; for arrayed chips or wafer-level processes, spin coating, blade coating, or spraying can be used. The coating thickness can be determined based on the phosphor particle concentration, target color coordinates, and the height of the lens array 41. Preferably, the thickness of the uncured phosphor layer 4 is greater than the height of the lens unit 411 to ensure that the lens array inversion structure of the metal template 8 can be fully filled during imprinting.

[0079] In step S3, the metal template 8 can be a nickel template, a stainless steel template, a copper template, or a composite template with a metal layer on the surface. The lens array inversion structure inside the metal template 8 can be made by precision machining, laser processing, electroforming, photolithography and electroforming combined, or other microstructure processing technology. To facilitate demolding, a fluorinated demolding layer, a silane demolding layer, or other low surface energy demolding layers can be provided on the surface of the metal template 8.

[0080] In step S4, the pressing pressure and pressing time should be such that the phosphor layer 4 fully fills the lens array inversion structure without damaging the Micro-LED chip; the curing method can be ultraviolet curing, ultraviolet-visible light curing, or a combination of ultraviolet curing and auxiliary heat treatment.

[0081] In step S5, the encapsulation medium layer 5 can be made of transparent silicone or transparent resin and formed by dispensing, molding, potting or coating.

[0082] In step S6, the transparent cover plate 9 can be a glass cover plate, a quartz cover plate, a sapphire cover plate, or a transparent resin cover plate. The transparent cover plate 9 can provide external protection for the phosphor layer 4 and the lens array 41 on its surface, and improve the flatness and mechanical stability of the light-emitting side encapsulation structure.

[0083] When the micro-LED light-emitting structure includes a protrusion array 6, that is, for embodiment 2, before step S2, the following is also included: on the light-emitting side of the n-GaN layer 3, a protrusion array 6 with a refractive index higher than that of the phosphor layer 4 is formed by imprinting and curing. In step S2, the phosphor layer 4 is formed by dispensing, spin coating, scraping or spraying, and covers the raised array 6.

[0084] In this embodiment, when forming the protrusion array 6 before step S2, a transparent high-refractive-index curable material can be coated on the light-emitting side of the n-GaN layer 3 first, and then pressed using an imprint template with an inverted structure of the protrusion array 6, so that the transparent high-refractive-index curable material forms a predetermined shape of transparent protrusions 61. Subsequently, the protrusion array 6 is shaped by ultraviolet curing, ultraviolet-visible light curing or thermal assisted curing, and finally the imprint template is removed. The above method does not require dry etching of the n-GaN layer 3, which can reduce the risk of lattice damage, defect increase or contamination residue on the surface of the n-GaN layer 3.

[0085] The refractive index of the transparent material used for the protrusion array 6 is higher than that of the phosphor layer 4, preferably 1.75 to 2.10, for example, 1.75, 1.90, or 2.10; the height of the transparent protrusions 61 can be 0.5 μm to 5 μm, the bottom width can be 0.5 μm to 10 μm, and the arrangement period can be 1 μm to 20 μm. If the height of the transparent protrusions 61 is too low, its effect on changing the local incident angle is limited; if the height is too high, it may increase the filling difficulty during the coating of the phosphor layer 4. Therefore, an intermediate value can be selected by combining the thickness of the phosphor layer 4 and the coating viscosity, for example, a height of 2 μm, a bottom width of 5 μm, and a period of 10 μm.

[0086] In step S2, when the phosphor layer 4 covers the protrusion array 6 by dispensing, spin coating, scraping, or spraying, the phosphor layer 4 should have the fluidity to fill the gaps between adjacent transparent protrusions 61 and remain in an uncured or semi-cured state before imprinting the lens array 41. After the transparent protrusions 61 are embedded in the phosphor layer 4, a dot array 44 that matches the shape of the transparent protrusions 61 is formed on the side of the phosphor layer 4 near the n-GaN layer 3, thereby achieving optical interface undulation and mechanical fitting. When the lens array 41 is subsequently imprinted, the protrusion array 6 can anchor the bottom of the phosphor layer 4, reducing the overall lateral displacement of the phosphor layer 4 caused by the extrusion of the metal template 8.

[0087] When the phosphor layer 4 includes a first phosphor layer 42 and a second phosphor layer 43, that is, for Example 3: step S2 includes: coating the first phosphor layer 42 on the light-emitting side of the n-GaN layer 3; Step S3 includes: aligning and pressing the metal template 8 with the first fluorescent layer 42; Step S4 includes: curing the first fluorescent layer 42 and removing the metal template 8 to form a lens array 41, coating the second fluorescent layer 43 onto the lens array 41 and curing it to form a flat light-emitting surface 432.

[0088] In this embodiment, when preparing the double-layer phosphor layer 4, a first phosphor layer 42 material can be coated on the light-emitting side of the n-GaN layer 3. The first phosphor layer 42 material includes a first transparent base layer 421 and phosphor particles with a high concentration. After the first phosphor layer 42 material is coated, the first phosphor layer 42 is aligned and pressed together using a metal template 8, so that the first phosphor layer 42 material fills the lens array inversion structure of the metal template 8. Then, the first phosphor layer 42 is cured while maintaining the pressed state, so that the lens array 41 is stably formed on the side surface of the first phosphor layer 42 facing away from the n-GaN layer 3.

[0089] After the metal template 8 is removed, the second fluorescent layer 43 material is coated onto the lens array 41 of the first fluorescent layer 42. The second fluorescent layer 43 material includes a second transparent base layer 433 and low-concentration phosphor particles, and has the fluidity to flow into the gaps between the concave and convex parts of the lens array 41. The second fluorescent layer 43 material fills the surface undulations of the lens array 41 under leveling or slight pressing conditions, and after curing, forms a concave array 431 on the side close to the first fluorescent layer 42 and a flat light-emitting surface 432 on the side away from the first fluorescent layer 42. The coating amount of the second fluorescent layer 43 should at least cover the highest point of the lens array 41 to avoid local concavity or exposed lens peaks on the flat light-emitting surface 432.

[0090] This fabrication sequence allows the formation of the lens array 41 and the planarization of the second fluorescent layer 43 to be completed in steps, which can avoid the morphology reflow problem caused by the simultaneous formation of the lens array 41 and the planar light-emitting surface 432 in the same uncured system. At the same time, since the lens array 41 is retained at the internal interface of the first fluorescent layer 42 and the second fluorescent layer 43, the lens array 41 can still deflect light by means of the refractive index difference between N11 and N12, while the outer planar light-emitting surface 432 facilitates the subsequent formation of the encapsulation medium layer 5.

[0091] In summary, this application provides a phosphor layer 4 on the light-emitting side of the n-GaN layer 3 and forms a lens array 41 on the surface of the phosphor layer 4 or its internal interface, enabling the phosphor layer 4 to simultaneously possess wavelength conversion, refractive index transition, and light emission direction control functions. The refractive index N1 of the phosphor layer 4 is located between the refractive index N2 of the n-GaN layer 3 and the refractive index N3 of the encapsulation dielectric layer 5, which can reduce the abrupt change in refractive index and reflection loss at the light-emitting side interface. The lens array 41 can refract and deflect the light passing through it, causing the light deviating from the normal direction to concentrate in a direction perpendicular to the surface of the phosphor layer 4. The reflective layer 7 can recover the backlight incident on the p-GaN layer 1 side and allow it to re-enter the dimming path on the light-emitting side of the n-GaN layer 3.

[0092] Furthermore, by setting lens units 411 with a height that gradually increases from the center to the edge of phosphor layer 4 and an aperture that gradually decreases from the center to the edge of phosphor layer 4, light from different light-emitting areas can be differentiated and focused. By setting a protrusion array 6 and a dot array 44 that matches its shape, the optical interface between n-GaN layer 3 and phosphor layer 4 can be improved without etching n-GaN layer 3, and the positional stability of phosphor layer 4 during the imprinting process can be improved. By setting a first phosphor layer 42 and a second phosphor layer 43, the main wavelength conversion, lens array 41 forming, internal refraction dimming, and planarization encapsulation can be layered and implemented.

[0093] Therefore, the micro-LED light-emitting structure of this application can improve the light utilization rate on the light-emitting side and improve the light emission direction concentration without relying on an additional independent collimating lens or directly etching the n-GaN layer 3. It is suitable for micro-LED light-emitting units or micro-LED arrays in digital automotive lights that require high brightness directional light emission and light emission collimation.

[0094] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A micro-LED light-emitting structure for digital vehicle lights, characterized in that, include: A p-GaN layer (1), a light-emitting layer (2), an n-GaN layer (3), a phosphor layer (4), and an encapsulation dielectric layer (5) are sequentially arranged along the light-emitting direction; The phosphor layer (4) is disposed on the light-emitting side of the n-GaN layer (3). The phosphor layer (4) is provided with a lens array (41) in the light-emitting direction. The lens array (41) includes a plurality of lens units (411) arranged in an array and protruding in the light-emitting direction. The lens units (411) are used to deflect part of the off-axis light rays within the effective aperture toward the optical axis side of the lens unit (411). The refractive indices N1 of the phosphor layer (4), N2 of the n-GaN layer (3), and N3 of the encapsulation medium layer (5) satisfy the following: N2>N1>N3.

2. The micro-LED light-emitting structure for digital vehicle lights according to claim 1, characterized in that: The sagittal height of the plurality of lens units (411) gradually increases from the center to the edge of the phosphor layer (4); The aperture of the plurality of lens units (411) gradually decreases from the center to the edge of the phosphor layer (4).

3. The micro-LED light-emitting structure for digital vehicle lights according to claim 1, characterized in that: It also includes a protrusion array (6), which is disposed on the side of the n-GaN layer (3) near the phosphor layer (4). The protrusion array (6) includes a plurality of transparent protrusions (61) arranged in an array. The phosphor layer (4) near the n-GaN layer (3) is provided with a dot array (44), which includes a plurality of dots (441) that correspond one-to-one with the transparent protrusions (61) and match their shapes.

4. The micro-LED light-emitting structure for digital vehicle lights according to claim 1, characterized in that, The phosphor layer (4) includes: The first fluorescent layer (42) is disposed on the light-emitting side of the n-GaN layer (3), and the lens array (41) is disposed on the surface of the first fluorescent layer (42) facing away from the n-GaN layer (3); The second fluorescent layer (43) is disposed on the surface of the lens array (41) of the first fluorescent layer (42). A recessed array (431) is formed on the side of the second fluorescent layer (43) close to the first fluorescent layer (42). The recessed array (431) matches the shape of the lens array (41). A flat light-emitting surface (432) is provided on the other side.

5. The micro-LED light-emitting structure for digital vehicle lights according to claim 4, characterized in that: The first fluorescent layer (42) includes a first transparent substrate (421), and the second fluorescent layer (43) includes a second transparent substrate (433). The refractive index N11 of the first transparent substrate (421) and the refractive index N12 of the second transparent substrate (433) satisfy: N2>N11>N12>N3.

6. The micro-LED light-emitting structure for digital vehicle lights according to claim 5, characterized in that: In terms of mass fraction, both the first transparent substrate (421) and the second transparent substrate (433) are filled with phosphor particles. The phosphor particle concentration K1 in the first transparent substrate (421) and the phosphor particle concentration K2 in the second transparent substrate (433) satisfy: K1>K2. The thickness of the second fluorescent layer (43) is less than the thickness of the first fluorescent layer (42).

7. The micro-LED light-emitting structure for digital vehicle lights according to claim 1, characterized in that: It also includes a reflective layer (7) disposed on the other side of the p-GaN layer (1) away from the light-emitting layer (2), and the reflective layer (7) is configured to reflect the light incident on the p-GaN layer (1) to the light-emitting side where the n-GaN layer (3) is located.

8. A method for fabricating a microLED light-emitting structure for digital vehicle lights, used to fabricate a microLED light-emitting structure as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Provide an epitaxial wafer, the epitaxial wafer comprising a p-GaN layer (1), a light-emitting layer (2) and an n-GaN layer (3) arranged sequentially along the light-emitting direction; S2. The light-emitting side surface of the n-GaN layer (3) is cleaned and surface-treated, and a phosphor layer (4) is coated on it. S3. Set a metal template, the metal template having a lens array inversion structure inside, align the metal template with the phosphor layer (4) and press them together; S4. Maintain the pressed state of the metal template and cure the phosphor layer (4). After curing, remove the metal template so that the phosphor layer (4) forms a lens array (41). S5. An encapsulation medium layer (5) is formed on the side of the phosphor layer (4) opposite to the n-GaN layer (3).

9. A method for fabricating a micro-LED light-emitting structure for digital vehicle lights according to claim 8, characterized in that, When the micro-LED light-emitting structure includes a protrusion array (6), before step S2, the method further includes: forming a protrusion array (6) with a refractive index higher than that of the phosphor layer (4) on the light-emitting side of the n-GaN layer (3) by imprinting and curing. In step S2, the phosphor layer (4) is formed by dispensing, spin coating, scraping or spraying, and covers the protrusion array (6).

10. A method for fabricating a microLED light-emitting structure for digital vehicle lights according to claim 8, characterized in that, When the phosphor layer (4) includes a first phosphor layer (42) and a second phosphor layer (43), step S2 includes: coating the first phosphor layer (42) on the light-emitting side of the n-GaN layer (3); Step S3 includes: aligning and pressing the metal template (8) with the first fluorescent layer (42); Step S4 includes: curing the first fluorescent layer (42) and removing the metal template (8) to form a lens array (41), coating the second fluorescent layer (43) onto the lens array (41) and curing it to form a flat light-emitting surface (432).

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