Enhanced Micro LED display chip and preparation method thereof

Abstract

The invention discloses an enhanced Micro LED (Light Emitting Diode) display chip and a preparation method thereof. The enhanced Micro LED display chip comprises a first substrate, an LED epitaxial layer and at least one photonic crystal microstructure layer, the first substrate, the LED epitaxial layer and the at least one photonic crystal microstructure layer are stacked in the thickness direction, the photonic crystal microstructure layer comprises a plurality of photonic crystal microstructure units, and each photonic crystal microstructure unit comprises periodically arranged micro-nano structures. A Mie scattering microstructure formed by Mie ball scattering particles is further arranged in the micro-nano structure, and the Mie scattering microstructure and the micro-nano structure form a local resonance structure, so that light emitted by the Micro LED unit is locally enhanced. A local resonance structure can be formed by introducing Mie ball scattering particles into the micro-nano structure, and a photonic band gap can be formed by overlapping the Mie ball scattering particles with the photonic crystal microstructure layer to form a dual enhancement mechanism, so that light emitted by the Micro LED unit is locally enhanced, angle divergence of emergent light can be inhibited, and light emitting efficiency and intensity are improved.

Description

Technical Field

[0001] This invention relates to a Micro LED display chip, specifically to an enhanced Micro LED display chip and its fabrication method, belonging to the field of Micro LED technology. Background Technology

[0002] Micro LED (micro-light-emitting diode) displays, as a next-generation display technology, have significant advantages in brightness, contrast, power consumption, and response speed. However, to achieve full-color display, red, green, and blue light sources are required. Currently, blue LED chips combined with red / green quantum dot color conversion films (QDCF) or printed patterns (QDPR) are widely used to achieve red and green light emission.

[0003] However, the current quantum dot conversion efficiency is still limited by two key issues: 1. Low excitation light utilization: Blue light is not effectively used to excite QDs, resulting in energy waste; 2. Limited light extraction efficiency: The light emitted by QDs suffers from severe total reflection, scattering and loss in the waveguide layer, interface and colloid, which reduces the light extraction efficiency. Summary of the Invention

[0004] The main objective of this invention is to provide an enhanced Micro LED display chip and its fabrication method to overcome the shortcomings of the prior art.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: This invention provides an enhanced Micro LED display chip, comprising: [amount of components stacked in the thickness direction]. First substrate; An LED epitaxial layer is located on the first substrate; the LED epitaxial layer includes a plurality of Micro LED units arranged in an array, the Micro LED units are electrically connected to the first substrate and can be driven independently, and the light-emitting surface of the Micro LED units faces away from the first substrate. At least one photonic crystal microstructure layer is disposed on the light-emitting surface of the Micro LED unit; the photonic crystal microstructure layer includes multiple photonic crystal microstructure units, one photonic crystal microstructure unit corresponds to one Micro LED unit, the photonic crystal microstructure unit includes periodically arranged micro / nano structures, the micro / nano structures are used to adjust the emission angle and emission area of ​​the light emitted by the Micro LED unit, the micro / nano structures also include Mie scattering microstructures composed of Mie sphere scattering particles, the micro / nano structures and Mie sphere scattering particles form a local resonance structure, which can at least form a photonic bandgap, thereby locally enhancing the light emitted by the Micro LED unit.

[0006] This invention also provides a method for fabricating the enhanced Micro LED display chip, comprising: An LED epitaxial layer is formed on a first substrate. The LED epitaxial layer includes a plurality of Micro LED units arranged in an array. The Micro LED units are electrically connected to the first substrate and can be driven independently. The light-emitting surface of the Micro LED units faces away from the first substrate. A photonic crystal microstructure layer is formed on the light-emitting surface of the Micro LED unit. The photonic crystal microstructure layer includes multiple photonic crystal microstructure units, with one photonic crystal microstructure unit corresponding to one Micro LED unit. The photonic crystal microstructure unit contains periodically arranged micro-nano structures, allowing Mie sphere scattering particles to be deposited within the micro-nano structures to form a localized Mie resonance structure, thereby obtaining the photonic crystal microstructure layer and fabricating the enhanced Micro LED display chip.

[0007] This invention also provides the application of the enhanced Micro LED display chip in Micro LED display devices.

[0008] Accordingly, embodiments of the present invention also provide a Micro LED display device, which includes: a plurality of the enhanced Micro LED display chips.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) The enhanced Micro LED display chip provided by this invention constructs a periodic photonic crystal microstructure on the surface of the Micro LED and sets Mie sphere scattering particles therein. The combination of the photonic crystal microstructure and the Mie sphere scattering particles forms a local resonant structure, which can form a photonic bandgap of a specific frequency. This allows the incident light to be locally reflected or scattered in the structure, thereby controlling the incident light distribution and the coupling direction of the emitted light and generating a local light field enhancement, thereby improving the quantum dot excitation efficiency (about 20-30%). Under the same driving conditions, the light emission intensity is increased by more than 2 times (compared to the structure without the introduction of photonic crystal microstructure and Mie sphere scattering particles), solving the problem of energy loss and efficiency bottleneck in the existing QDs-Micro LED structure. 2) The RGB color saturation of the Micro LED display chip of the present invention is improved, especially the color deviation is significantly reduced in high brightness environment, and the overall device lifespan is increased by more than 30%. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 A simplified structural diagram of an enhanced Micro LED display chip provided in a typical embodiment of the present invention; Figure 2 This is a top view of the photonic crystal microstructure layer of an enhanced Micro LED display chip provided in a typical embodiment of the present invention; Figure 3 This is a partial enlarged cross-sectional view of an enhanced Micro LED display chip provided in a typical embodiment of the present invention; Figure 4 A simplified structural diagram of an enhanced Micro LED display chip provided for another typical embodiment of the present invention; Figure 5 A simplified structural diagram of an enhanced Micro LED display chip provided for another typical embodiment of the present invention; Figure 6 A simplified structural diagram of an enhanced Micro LED display chip provided for another typical embodiment of the present invention; Figure 7 A flowchart illustrating a method for fabricating an enhanced Micro LED display chip, as provided in a typical embodiment of the present invention; Figure 8 This is a flowchart illustrating a method for fabricating an enhanced Micro LED display chip, as provided in another typical embodiment of the present invention.

[0012] Reference numerals: 100-first substrate, 200-LED epitaxial layer, 210-Micro LED unit, 300-photonic crystal microstructure layer, 310-photonic crystal microstructure unit, 311-micro / nano structure, 312-Mie sphere scattering particles. Detailed Implementation

[0013] Given the shortcomings of current technologies, photonic crystal structures are considered an effective means of controlling light field distribution and enhancing excitation efficiency and luminescence coupling efficiency. Through long-term research and extensive practice, the inventors of this invention have proposed the technical solution of this invention, which mainly provides an enhanced Micro LED display chip. By constructing a periodic photonic crystal microstructure on the surface of the Micro LED unit and placing Mie sphere scattering particles within it, a local resonance structure is formed by combining the photonic crystal microstructure and the Mie sphere scattering particles. This creates a photonic bandgap of a specific frequency, allowing incident light to be locally reflected or scattered within the structure. By controlling the incident light distribution and the coupling direction of emitted light, a local light field enhancement is generated, thereby improving the quantum dot excitation efficiency and photon extraction efficiency, and solving the energy loss and efficiency bottleneck problems in existing QDs-Micro LED structures.

[0014] The following will further explain the technical solution, its implementation process, and its principles. However, it should be understood that within the scope of this invention, the above-mentioned technical features of this invention and the technical features specifically described below (in embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here.

[0015] As one aspect of the technical solution of the present invention, an enhanced Micro LED display chip includes components stacked in the thickness direction: First substrate; An LED epitaxial layer is located on the first substrate; the LED epitaxial layer includes a plurality of Micro LED units arranged in an array, the Micro LED units are electrically connected to the first substrate and can be driven independently, and the light-emitting surface of the Micro LED units faces away from the first substrate. At least one photonic crystal microstructure layer is disposed on the light-emitting surface of the Micro LED unit; the photonic crystal microstructure layer includes multiple photonic crystal microstructure units, one photonic crystal microstructure unit corresponds to one Micro LED unit, the photonic crystal microstructure unit includes periodically arranged micro / nano structures, the micro / nano structures are used to adjust the emission angle and emission area of ​​the light emitted by the Micro LED unit, the micro / nano structures also include Mie scattering microstructures composed of Mie sphere scattering particles, the micro / nano structures and Mie sphere scattering particles form a local resonance structure, which can at least form a photonic bandgap, thereby locally enhancing the light emitted by the Micro LED unit.

[0016] The principle of photonic bandgap formation based on local enhancement in this invention lies in the fact that two-dimensional or three-dimensional periodically arranged micro / nano structures can form photonic bandgap of specific frequencies. This allows light emitted from the Micro LED unit to be locally reflected or scattered within the structure, resulting in localized optical field enhancement and improved excitation efficiency. When the wavelength of the light matches the period of the photonic crystal structure, Bragg diffraction conditions are generated, trapping the light in a local region and increasing the chance of coupling with the quantum dot.

[0017] Simultaneously, the combination of photonic crystal microstructure and Mie sphere scattering particles forms a localized resonance structure. The principle is that the particle size of the Mie sphere scattering particles matches the wavelength of the light emitted by the Micro LED unit, generating a Mie resonance effect and creating a localized electromagnetic field enhancement. This, combined with the photonic crystal microstructure, forms a dual enhancement mechanism. The Mie sphere scattering particles can also scatter light into the quantum dot conversion layer, making the quantum dots more uniformly excited and suppressing the angular divergence of the light emitted from the quantum dot conversion layer. Technically, this improves light utilization, increases the light intensity of red and green quantum dots by more than two times, and enhances color saturation; it is particularly beneficial for Micro LED full-color display devices, reducing color shift at high brightness.

[0018] Figure 1 This is a simplified structural diagram of an enhanced Micro LED display chip provided in one embodiment of the present invention. Figure 2 This is a top view of the photonic crystal microstructure layer of an enhanced Micro LED display chip. The enhanced Micro LED display chip includes a first substrate 100, an LED epitaxial layer 200, and a photonic crystal microstructure layer 300.

[0019] The LED epitaxial layer 200 is located on the first substrate 100. The LED epitaxial layer 200 includes a plurality of Micro LED units 210 arranged in an array. The Micro LED units 210 are electrically connected to the first substrate 100 and can be driven independently. The light-emitting surface of the Micro LED unit 210 faces away from the first substrate 100. The Micro LED unit 110 can refer to a miniature light-emitting diode with an effective light-emitting area of ​​less than 100μm, less than 50μm, less than 10μm, or even less than 5μm.

[0020] A photonic crystal microstructure layer 300 is disposed on the light-emitting surface of the Micro LED unit 200. The photonic crystal microstructure layer 300 includes multiple arrayed photonic crystal microstructure units 310, with one photonic crystal microstructure unit 310 corresponding to one Micro LED unit 210. The photonic crystal microstructure unit 310 contains periodically arranged micro / nano structures 311, which are used to adjust the emission angle and emission area of ​​the light emitted by the Micro LED unit 210. The micro / nano structure 311 also contains a Mie scattering microstructure composed of Mie sphere scattering particles 312. The micro / nano structure 311 and the Mie sphere scattering particles 312 form a local resonance structure, which can at least form a photonic bandgap, thereby locally enhancing the light emitted by the Micro LED unit 210.

[0021] In embodiments of the present invention, such as Figure 3 As shown, the light-emitting surface of the Micro LED unit 210 is the side surface of the Micro LED unit 210 facing away from the first substrate 100, that is, the Micro LED unit 210 emits light towards the top of the first substrate 100. Therefore, the photonic crystal microstructure layer 300 is disposed on the side surface of the LED epitaxial layer 200 facing away from the first substrate 100. In this embodiment of the invention, the first substrate 100 may include a substrate and a film layer formed on the substrate. The film layer may include a buffer layer or a circuit layer containing CMOS devices and TFT devices, etc. These CMOS devices and TFT devices can constitute a driving circuit, which is used to drive the Micro LED unit 210 in the LED epitaxial layer 200 to emit light. The substrate material can be a semiconductor material such as silicon, silicon carbide, gallium nitride, germanium, gallium arsenide, or indium phosphide, or a non-conductive material such as glass, plastic, or sapphire wafer.

[0022] Furthermore, the material of the Micro LED unit 210 has an emission wavelength of 450~460 nm.

[0023] In some preferred embodiments, the Micro LED unit 210 includes an InGaN / GaN multiple quantum well structure, but is not limited thereto.

[0024] In this embodiment of the invention, multiple photonic crystal microstructure units 310 are respectively arranged correspondingly to multiple Micro LED units 210. That is, the projection of each photonic crystal microstructure unit 310 on the first substrate 100 at least covers the projection of the light-emitting area of ​​one Micro LED unit 210 on the first substrate 100, so as to adjust the emission angle of the light emitted by the multiple Micro LED units 210 by the multiple photonic crystal microstructure units 310 respectively.

[0025] In embodiments of the present invention, such as Figure 3 As shown, the light-emitting surface of the enhanced Micro LED display chip is the surface above the first substrate 100. Since the photonic crystal microstructure layer 300 is located on the light-emitting surface of the Micro LED unit 210, the light emitted by the Micro LED unit 210 will be reflected, refracted, scattered, or diffracted by the photonic crystal microstructure layer 310 before exiting. The photonic crystal microstructure layer 310 allows light emitted from the Micro LED unit 210 that is directed towards the left and right sides of the first substrate 100 to exit upwards onto the first substrate 100. This ensures that as much light as possible is emitted upwards from the first substrate 100, maximizing the amount of light emitted from the light-emitting surface of the enhanced Micro LED display chip. This, in turn, increases the light output and light extraction efficiency of the enhanced Micro LED display chip, thereby improving its brightness and contrast, and ultimately enhancing its display performance.

[0026] In some embodiments of the present invention, such as Figure 2 and Figure 3 As shown, the micro / nano structures 311 are arranged periodically, with a spacing of 200–500 nm between adjacent structures, satisfying the photonic bandgap modulation conditions. In actual fabrication, a process deviation of ±10% in the period of the micro / nano structures is permissible, yet the optical field modulation effect can still be achieved.

[0027] In some preferred embodiments of the present invention, the micro / nano structure may include one or more combinations of periodically arranged groove arrays, columnar arrays, and hole arrays, but is not limited thereto. For example, the photonic crystal structure parameters can be optimized using electromagnetic simulation methods (such as FDTD) to design two-dimensional square lattice hole array structures or hexagonal columnar array structures.

[0028] Furthermore, the aperture of the aperture array is 100~300nm.

[0029] Furthermore, the depth of the groove array or hole array is 150~400nm.

[0030] Furthermore, the height of the columnar array is 150~350nm.

[0031] In some embodiments of the present invention, the photonic crystal microstructure layer 300 is made of a high-refractive-index material or a medium-refractive-index material, with an equivalent refractive index of 1.4 to 2.5, including one or more combinations of TiO2, Si3N4, SU-8, SiO2, etc., but not limited to these. Alternatively, the photonic crystal microstructure layer can be formed directly on the surface of the LED epitaxial layer 200 by an etching process.

[0032] Furthermore, the photonic crystal microstructure layer 300 is preferably made of a material with a refractive index of 1.8 to 2.5.

[0033] Furthermore, the thickness of the photonic crystal microstructure layer 300 is 100~500 nm.

[0034] In some embodiments of the present invention, the particle size of the Mie sphere scattering particles 312 is 50~300 nm, preferably 80~200 nm.

[0035] In some embodiments of the present invention, the Mie sphere scattering particles 312 may be one or a combination of TiO2 nanospheres, SiO2 nanospheres, Al2O3 nanospheres, ZrO2 nanospheres, etc., but are not limited thereto.

[0036] In other embodiments, the LED epitaxial layer 200 may also have other film layers between it and the first substrate 100, such as a bonding layer. The LED epitaxial layer 200 can be adhered to or bonded to the surface of the first substrate 100 through the bonding layer.

[0037] Furthermore, the Micro LED unit 210 includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer sequentially stacked on the first substrate 100; the first semiconductor layers of multiple Micro LED units 210 are continuously disposed; the first substrate 100 has a driving circuit and multiple driving contacts electrically connected to the driving circuit, with one driving contact corresponding to one Micro LED unit 210; the Micro LED unit 210 also includes a first electrode layer located on the second semiconductor layer; the bonding layer and the LED epitaxial layer 200 have openings exposing the driving contacts; the first electrode layer is electrically connected to the driving contacts through the openings.

[0038] The driving circuit may include multiple circuit units, each of which provides a driving signal to a Micro LED unit 210 to individually control the brightness of that Micro LED unit 210. The signal output terminal of each circuit unit is electrically connected to a contact to apply a driving voltage to the second semiconductor layer through the contact and the first electrode layer.

[0039] In a preferred embodiment, the second semiconductor layer is an n-type semiconductor layer, and correspondingly, the first semiconductor layer is a p-type semiconductor layer. The bonding layer is made of conductive metal. The bonding layer is electrically connected to the first semiconductor layer. An anode voltage is applied to the bonding layer and the first semiconductor layer, and a cathode voltage is applied to the second semiconductor layer. Therefore, the light-emitting layer of the Micro LED unit 210 can be driven to emit light.

[0040] It should be noted that the first semiconductor layer can be a p-type semiconductor layer, which can be formed by doping or ion implantation, such as a p-type GaN or InGaN layer. The first semiconductor layer can be a multilayer structure. The second semiconductor layer is an n-type semiconductor layer, which can also be formed by doping or ion implantation, such as an n-type GaN or InGaN layer. The second semiconductor layer can be a multilayer structure. The light-emitting layer is a layer in which holes provided from the first semiconductor layer and electrons provided from the second semiconductor layer recombine and output light of a specific wavelength. The light-emitting layer can have a single quantum well structure or a multiple quantum well (MQW) structure, and can have well layers and barrier layers stacked alternately. In another embodiment of the present invention, the first semiconductor layer can be an n-type semiconductor layer and the second semiconductor layer can be a p-type semiconductor layer.

[0041] The bonding layer can be made of conductive materials, such as metals or metal alloys, specifically including Au, Sn, In, Cu, or Ti. Alternatively, the bonding layer can be made of non-conductive materials, such as polyimide, polydimethylsiloxane, or Su. 8. Photoresist, etc. It is understood that if the bonding layer is made of a non-conductive material, the bonding layer cannot function as an anode together with the first semiconductor layer; in this case, the anode only includes the first semiconductor layer. Of course, in some embodiments, the bonding layer and the first semiconductor layer may also have a second electrode layer, which can serve as the anode of the Micro LED unit 210.

[0042] Based on any of the above embodiments, in some embodiments of the present invention, such as Figure 4 As shown, Figure 4 This is a simplified structural diagram of an enhanced Micro LED display chip provided in another embodiment of the present invention. The enhanced Micro LED display chip further includes a quantum dot conversion layer, which is disposed on the surface of the photonic crystal microstructure layer (i.e., the side of the photonic crystal microstructure layer facing away from the first substrate) and / or embedded in the photonic crystal microstructure layer, for wavelength conversion of the light emitted by the Micro-LED unit.

[0043] In some preferred embodiments, the quantum dot conversion layer comprises a composite material formed of quantum dots and a polymer. The quantum dots include red or green quantum dots.

[0044] In some preferred embodiments, the emission peak of the red quantum dot is 600~630 nm, and the emission peak of the green quantum dot is 510~530 nm.

[0045] In some preferred embodiments, the thickness of the quantum dot conversion layer is 1~10 µm.

[0046] In some preferred embodiments, the quantum dots may include one or more combinations of group IV quantum dots, group II-VI quantum dots, group IV-VI quantum dots, group III-V quantum dots, etc., for example, any one of red and green luminescent quantum dots such as CdSe / ZnS, CdS / ZnS, CdZnSe / ZnS, CdZnSeS / ZnS, CdSe / CdS, InP / ZnS, AgInGaS / ZnS, etc., embedded in a polymer.

[0047] Furthermore, the polymer in the quantum dot conversion layer is polymerized from acrylate monomers, but is not limited to this.

[0048] Furthermore, the surface of the quantum dots can be further coated with short-chain organic ligands or inorganic shells to improve their stability under UV curing and long-term working conditions; wherein, the short-chain organic ligands include, but are not limited to, thiol ligands, carboxylic acid ligands, phosphonic acid ligands or combinations thereof, such as 3-mercaptopropionic acid, mercaptoacetic acid, oleic acid, decanoic acid, octylphosphonic acid, etc.; the inorganic shells include, but are not limited to, one or more combinations of ZnS, ZnSe, SiO2, Al2O3, etc.

[0049] In some embodiments of the present invention, such as Figure 5 As shown, Figure 5 This is a simplified structural diagram of an enhanced Micro LED display chip provided in another embodiment of the present invention. The enhanced Micro LED display chip may further include a light-transmitting encapsulation layer, which is disposed on the surface of the quantum dot conversion layer away from the first substrate.

[0050] Furthermore, the light-transmitting encapsulation layer is used to protect the quantum dot conversion layer and improve device durability. Specifically, the material of the light-transmitting encapsulation layer may include transparent polymers or inorganic materials.

[0051] Furthermore, the material of the light-transmitting encapsulation layer includes, but is not limited to, organosilicon polymers, Si3N4, or SiO2.

[0052] In some preferred embodiments, the thickness of the light-transmitting encapsulation layer is 2 to 10 µm.

[0053] In other preferred embodiments, the enhanced Micro LED display chip of the present invention can be a multi-level coupled enhanced light-emitting structure integrating a photonic crystal microstructure layer and a quantum dot conversion layer. That is, two photonic crystal microstructure layers with different periods are introduced on the light-emitting surface of the LED epitaxial layer to respectively control the light emitted by the Micro-LED unit and the light emitted by the quantum dot conversion layer, maximizing the light coupling efficiency. Specifically, the enhanced Micro LED display chip includes multiple photonic crystal microstructure layers, and the photonic crystal microstructure unit structures in adjacent photonic crystal microstructure layers are different, as are the spacing distances between adjacent micro / nano structures.

[0054] Specifically, such as Figure 6 As shown, Figure 6 A simplified structural diagram of an enhanced Micro LED display chip provided in another embodiment of the present invention is shown, which includes: a first substrate, an LED epitaxial layer, a first photonic crystal microstructure layer, a quantum dot conversion layer, and a second photonic crystal microstructure layer stacked sequentially in the thickness direction. The spacing between adjacent micro- and nanostructures in the first and second photonic crystal microstructure layers is different. The first photonic crystal microstructure layer is used to control the light emitted by the Micro-LED unit, and the second photonic crystal microstructure layer is used to control the light emitted by the quantum dot conversion layer.

[0055] As another aspect of the technical solution of this invention, it involves a method for fabricating an enhanced Micro LED display chip, such as... Figure 7 As shown, Figure 7 A flowchart illustrating a method for fabricating an enhanced Micro LED display chip according to an embodiment of the present invention includes: S1. An LED epitaxial layer is formed on a first substrate. The LED epitaxial layer includes a plurality of Micro LED units arranged in an array. The Micro LED units are electrically connected to the first substrate and can be driven independently. The light-emitting surface of the Micro-LED units faces away from the first substrate. S2. A photonic crystal microstructure layer is formed on the light-emitting surface of the Micro-LED unit. The photonic crystal microstructure layer includes multiple photonic crystal microstructure units, with one photonic crystal microstructure unit corresponding to one Micro-LED unit. The photonic crystal microstructure unit contains periodically arranged micro-nano structures, forming a local Mie resonance structure within the micro-nano structures, thereby obtaining a photonic crystal Mie sphere scattering particle deposition microstructure layer and fabricating an enhanced Micro LED display chip.

[0056] In some embodiments of the present invention, the fabrication method includes: constructing a periodically arranged micro-nano structure on the light-emitting surface of the Micro-LED unit by at least one of the following methods: nanoimprinting, dry etching, focused ion beam, electron beam exposure, optical interference exposure, etc.

[0057] In some embodiments of the present invention, the preparation method includes: at least using a capillary-assisted self-assembly method to deposit Mie sphere scattering particles into a micro / nano structure.

[0058] In some embodiments of the present invention, the preparation method includes: setting multiple photonic crystal microstructure layers, wherein the photonic crystal microstructure unit structures in adjacent photonic crystal microstructure layers are different and the spacing between adjacent micro / nano structures is different.

[0059] In some preferred embodiments of the present invention, the preparation method includes: A periodically arranged micro-nano structure with a first interval is constructed on the light-emitting surface of the Micro-LED unit, so that Mie sphere scattering particles are deposited in the micro-nano structure to form a first photonic crystal microstructure layer. A quantum dot conversion layer is disposed on the surface and / or inside the first photonic crystal microstructure layer; A periodically arranged micro / nano structure with a second spacing is constructed on the surface of the quantum dot conversion layer, so that Mie sphere scattering particles are deposited within the micro / nano structure to form a second photonic crystal microstructure layer. The first interval distance and the second interval distance are different.

[0060] In some embodiments of the present invention, such as Figure 8 As shown, the preparation method includes: coating a mixture of quantum dots and polymers and / or curable polymer precursors onto the surface of a photonic crystal microstructure layer and / or embedding it into the photonic crystal microstructure layer, and forming a quantum dot conversion layer on the surface and / or inside the photonic crystal microstructure layer by any one of ultraviolet curing, thermal curing, solvent evaporation film formation, etc.

[0061] In some preferred embodiments, the ultraviolet light wavelength used for ultraviolet curing is 365~405nm, and the curing time is 1~10min.

[0062] In some preferred embodiments, the thermosetting temperature is 60~150℃ and the time is 5~60min.

[0063] For some more preferred implementation schemes, please refer to Figure 8 As shown, the fabrication process of the enhanced Micro LED display chip includes the following steps: 1. Multiple Micro LED units are arranged in an array on a first substrate to obtain an LED epitaxial layer; 2. Construct a micro-nano structure photonic crystal microstructure unit containing a periodically arranged micro-nano structure in the Micro LED unit, and deposit Mie sphere scattering particles in the micro-nano structure; 3. Coating a mixture of quantum dots and polymer or curable polymer precursor to form a quantum dot conversion layer; 4. UV curing forms a quantum dot conversion layer with stable color; 5. Use a transparent polymer or inorganic coating as a light-transmitting encapsulation layer.

[0064] In some implementations, the encapsulation method includes, but is not limited to, spin coating, spraying or drop coating of a transparent polymer followed by UV curing or thermal curing to form a polymer light-transmitting encapsulation layer; or forming an inorganic light-transmitting encapsulation layer by atomic layer deposition, chemical vapor deposition or sputtering.

[0065] As another aspect of the technical solution of the present invention, it also relates to the application of the enhanced Micro LED display chip in Micro LED display devices.

[0066] Correspondingly, another aspect of the technical solution of the present invention also relates to a Micro LED display device, which includes: a plurality of the aforementioned enhanced Micro LED display chips.

[0067] The overall structure of the enhanced Micro LED display chip and Micro LED display device obtained by this invention can be patterned, enabling pixel-level red and green pattern control.

[0068] The specific embodiments of the present invention will be described in more detail below with reference to examples, but the examples do not constitute a limitation of the present invention. All modifications that are conceived or derived from the content disclosed in this invention are considered to be within the scope of protection of this invention.

[0069] All raw materials used in the embodiments of this invention were purchased from the market.

[0070] The instruments and equipment used in the following examples are all conventional equipment in the relevant fields, and the performance tests are all conducted in accordance with the requirements of conventional standards.

[0071] Example 1 This embodiment provides a Micro LED display chip that incorporates a Mie scattering microstructure to assist in localized blue light enhancement, combining a photonic crystal microstructure with Mie sphere scattering particles (TiO2 nanospheres) to form a localized resonant structure. The structure of this Micro LED display chip sequentially includes: a Micro LED blue light epitaxial structure, a SiO2 groove array + TiO2 nanosphere photonic crystal layer, a CdSe / ZnS red light quantum dot conversion layer, and a light-transmitting encapsulation layer.

[0072] The fabrication method of the Micro LED display chip enhanced by the Mie scattering microstructure includes the following steps: Step 1: Fabrication of SiO2 Groove Array A periodic SiO2 groove array with a period of approximately 400 nm and a groove depth of approximately 150 nm was constructed on the surface of a Micro LED blue light epitaxial structure with multiple arrayed Micro LED units using nanoimprint lithography.

[0073] Step 2: Self-assembly and deposition of TiO2 nanospheres TiO2 nanospheres with a particle size of 100 nm were dispersed in ethanol (concentration of approximately 5 mg / mL).

[0074] By using a capillary-assisted self-assembly method, a TiO2 nanosphere solution was dropped onto the surface of a groove array. The solvent was slowly evaporated at 40 °C, allowing the TiO2 nanospheres to preferentially deposit in the grooves and form a localized Mie resonance structure.

[0075] Step 3: Fabrication of the quantum dot conversion layer CdSe / ZnS red quantum dots are mixed with a polymer (PMMA or acrylic resin) at a mass ratio of approximately 1:8, and then spin-coated to form a quantum dot conversion layer with a thickness of approximately 2.0 μm.

[0076] Step 4: Annealing and Encapsulation After annealing at 80 °C for 15 min (to improve interfacial adhesion), fluorine-modified silicone encapsulation material is spin-coated and thermo-cured to form a hydrophobic and light-transmitting encapsulation layer to prevent moisture erosion.

[0077] After the enhanced Micro LED display chip was fabricated into a Micro LED display device, the test results showed that compared with the non-photonic crystal microstructure and TiO2 nanospheres, the blue light utilization rate of this Micro LED display device was increased by 25%, the quantum dot excitation efficiency was increased by 30%, the red and green light emission intensities were increased by 2.4 and 2.1 times respectively, and the color saturation was improved; and the luminous efficiency was still maintained at more than 90% when the operating temperature was increased to 105℃.

[0078] Example 2 This embodiment provides an enhanced red quantum dot Micro LED display chip constructed based on nanoimprint lithography. Its structure includes, in sequence: a Micro LED blue light epitaxial structure, a SiO2 hole array + TiO2 nanosphere photonic crystal layer, a CdSe / ZnS red light quantum dot conversion layer, and a light-transmitting encapsulation layer.

[0079] The fabrication method of this enhanced red quantum dot Micro LED display chip includes the following steps: Step 1: Photonic Crystal Template Preparation and Transfer UV nanoimprint photoresist was spin-coated onto the emitting surface of a Micro LED blue light epitaxial structure with multiple arrayed Micro LED units (3000 rpm for 30 s), and then pre-baked at 80 °C for 2 min.

[0080] Imprinting was performed using a quartz nanoimprint template, which has a two-dimensional periodic pore array structure with a period of approximately 300 nm and a pore size of approximately 150 nm. The imprinting pressure was 3 MPa, and the material was cured for 120 s under 365 nm ultraviolet light irradiation.

[0081] After demolding, the pattern is transferred to the SiO2 layer by reactive ion etching (CHF3 / O2, power 150 W) to form a two-dimensional SiO2 photonic crystal pore array structure with a pore depth of about 250 nm.

[0082] Step 2: Self-assembly and deposition of TiO2 nanospheres TiO2 nanospheres with a particle size of 50 nm were dispersed in ethanol (concentration of approximately 5 mg / mL).

[0083] By using a capillary-assisted self-assembly method, a TiO2 nanosphere solution was dropped onto the surface of a porous array structure. The solvent was slowly evaporated at 40 °C, allowing the TiO2 nanospheres to preferentially deposit within the porous array structure and form a localized Mie resonance structure.

[0084] Step 3: Preparation and Coating of Quantum Dot Mixture CdSe / ZnS core-shell structured red quantum dots were selected and dispersed in toluene at a concentration of 20 mg / mL to form a quantum dot solution.

[0085] The quantum dot solution was mixed with an acrylate UV-curable monomer (such as IBOA) and a photoinitiator (2% by mass), wherein the mass ratio of quantum dots to monomers was 1:6. The mixture was ultrasonically mixed for 10 min to obtain a homogeneous quantum dot mixture.

[0086] The quantum dot mixture was spin-coated onto the surface of a SiO2 photonic crystal array (2000 rpm for 30 s) to partially fill the array with quantum dots and form a continuous thin film on the surface.

[0087] Step 4: Curing of the quantum dot conversion layer Irradiation with 365 nm ultraviolet light for 3 min caused the acrylate monomers to crosslink and cure, forming a stable red quantum dot conversion layer with a thickness of approximately 1.5 μm.

[0088] Step 5: Preparation of the light-transmitting encapsulation layer Methyl vinyl siloxane-based silicone encapsulation material was spin-coated onto the surface of the quantum dot conversion layer (3000 rpm for 30 s), and then thermo-cured at 120 °C for 30 min to form a dense, transparent silicone encapsulation layer for isolating moisture and oxygen.

[0089] After the enhanced Micro LED display chip was fabricated into a Micro LED display device, the test results showed that its luminous intensity was increased by about 2.1 times compared with the non-photonic crystal microstructure and TiO2 nanospheres, the R9 color purity was increased to more than 96%, and the brightness decay was less than 10% after 500 h of 85 ℃ / damp heat aging.

[0090] Example 3 This embodiment provides an electro-green light-enhanced Micro LED display chip, the structure of which includes, in sequence: a MicroLED blue light epitaxial structure, a TiO2 columnar array + Al2O3 nanosphere photonic crystal layer, an InP / ZnS green quantum dot conversion layer, and an inorganic Si3N4 encapsulation layer.

[0091] The fabrication method of this green light-enhanced Micro LED display chip includes the following steps: Step 1: Construction of TiO2 pillar array photonic crystal A TiO2 thin film with a thickness of approximately 200 nm was deposited on the surface of a Micro LED blue light epitaxial structure with multiple arrayed Micro LED units by magnetron sputtering.

[0092] Spin-coating electron beam resist (PMMA, 950K, 3000 rpm, 60 s) writes a hexagonal periodic columnar array pattern in an electron beam lithography system. The period is about 240 nm and the column diameter is about 100 nm.

[0093] After development and reactive ion etching, a TiO2 columnar array photonic crystal structure is formed, with a column height of approximately 80 nm.

[0094] Step 2: Self-assembly and deposition of Al2O3 nanospheres Al2O3 nanospheres with a particle size of 150 nm were dispersed in ethanol (concentration of approximately 5 mg / mL).

[0095] By using a capillary-assisted self-assembly method, an Al2O3 nanosphere solution was dropped onto the surface of a TiO2 columnar array. The solvent was slowly evaporated at 40°C, allowing the Al2O3 nanospheres to preferentially deposit between the TiO2 columnar arrays, forming a localized Mie resonance structure.

[0096] Step 3: Fabrication of the quantum dot conversion layer InP / ZnS green quantum dots (toluene dispersion, concentration 15 mg / mL) were mixed with UV-curable resin at a mass ratio of 1:5, and 1.5 wt% of a photoinitiator (one of 2-hydroxy-2-methylphenylacetone (Darocur 1173), Irgacure 184, or Irgacure 2959) was added.

[0097] The mixture was coated onto the surface of the TiO2 columnar array using a dot coating method.

[0098] Step 4: UV curing A continuous quantum dot conversion layer with a thickness of approximately 1.2 μm was formed by irradiating with 365 nm ultraviolet light for 5 min.

[0099] Step 5: Inorganic Packaging A Si3N4 thin film was deposited on the surface of the quantum dot conversion layer using PECVD process at a deposition temperature of approximately 120 °C and a thickness of approximately 30 nm, serving as an inorganic barrier encapsulation layer.

[0100] Tests conducted after fabricating this enhanced Micro LED display chip into a Micro LED display device showed that, compared to non-photonic crystal microstructures and TiO2 nanospheres, the green light emission efficiency of this Micro LED display device was increased by 1.8 times; the emission angle directionality was enhanced, and the half-value angle was compressed to ±10°; color consistency was improved, making it suitable for wearable miniaturized displays.

[0101] Example 4 This embodiment provides a pixel-level patterned enhanced Micro LED display chip assisted by a photonic crystal template. It utilizes the photonic crystal structure as an optical trap to improve the orientation of the excitation region and achieve high-precision QDs pattern transfer.

[0102] The enhanced Micro LED display chip structure sequentially comprises: a Micro LED blue light epitaxial structure, a photonic crystal microstructure layer, a red / green quantum dot conversion layer, and a light-transmitting encapsulation layer. The photonic crystal microstructure layer is a two-dimensional periodic aperture array + ZrO2 nanosphere photonic crystal structure. The aperture array structure is either a square lattice aperture array or a hexagonal close-packed aperture array. The period of the two-dimensional aperture array photonic crystal is 280–320 nm, the aperture is 120–180 nm, and the aperture depth is 200–280 nm. The aperture array + ZrO2 nanosphere photonic crystal structure is used to spatially confine the quantum dot deposition area, suppressing the lateral diffusion of quantum dot material at pixel boundaries, thereby improving the boundary sharpness and color consistency of the pixel pattern.

[0103] The fabrication method of this enhanced Micro LED display chip includes the following steps: Step 1: Photonic Crystal Template Preparation On the light-emitting surface of a Micro LED blue light epitaxial structure with multiple arrayed Micro LED units, a two-dimensional periodic aperture array photonic crystal structure is constructed by nanoimprinting. The period of the aperture array is about 300 nm, which is used as a structural template for quantum dot patterning deposition.

[0104] Step 2: Self-assembly and deposition of ZrO2 nanospheres ZrO2 nanospheres with a particle size of 100 nm were dispersed in ethanol (concentration of approximately 5 mg / mL).

[0105] By using a capillary-assisted self-assembly method, a ZrO2 nanosphere solution was dropped onto the surface of a porous array. The solvent was slowly evaporated at 40 °C, allowing the ZrO2 nanospheres to preferentially deposit within the porous array and form a localized Mie resonance structure.

[0106] Step 3: Quantum Dot Patterning Deposition Using inkjet printing, red and green quantum dot inks are deposited on designated pixel areas, with the mass ratio of red and green quantum dots to UV-cured polymer in the ink being 1:4.

[0107] Step 4: Curing and Encapsulation After being irradiated with 365 nm ultraviolet light for 2 min, a patterned quantum dot conversion layer with a thickness of about 0.8 μm was formed. Subsequently, an organosilicon encapsulation layer was spin-coated and thermally cured to form a light-transmitting encapsulation layer.

[0108] After the enhanced Micro LED display chip was fabricated into a Micro LED display device, the test results showed that compared with the non-photonic crystal microstructure and ZrO2 nanospheres, the pixel positioning accuracy of the Micro LED display device is <±1 μm, the RGB pattern has no color crosstalk, and it is compatible with the Micro LED bare chip array transferred by micro transfer printing (μTP) technology.

[0109] Example 5 This embodiment provides a multi-level coupled enhanced Micro LED display chip that integrates a multi-layer photonic crystal microstructure layer and a quantum dot conversion layer. Two photonic crystal microstructure layers with different periods (i.e., the spacing between micro and nano structures) are introduced into the emitting surface of the Micro LED blue light epitaxial structure to respectively control the excitation light and the emission path of the light, thereby maximizing the light coupling efficiency.

[0110] The enhanced Micro LED display chip comprises, in sequence: a Micro LED blue light epitaxial structure, a first photonic crystal microstructure layer (excitation light modulation), a quantum dot conversion layer, a second photonic crystal microstructure layer (emission light orientation), and a light-transmitting encapsulation layer. The first photonic crystal microstructure layer is a two-dimensional columnar array + TiO2 nanosphere photonic crystal structure. The columnar array is a cylindrical array or a hexagonal columnar array structure with a period of approximately 220 nm, a column diameter of 80–120 nm, and a column height of 150–200 nm, used for localized enhancement and light field modulation of the Micro LED blue light excitation light. The second photonic crystal microstructure layer is a two-dimensional aperture array photonic crystal structure or a two-dimensional groove array structure + TiO2 nanospheres, with a period of approximately 400 nm and an aperture depth or groove depth of 200–250 nm, used to control the emission path and directionality of quantum dot light emission, improving light extraction efficiency and reducing the emission divergence angle. The two photonic crystal microstructure layers are decoupled from each other in terms of spatial position and periodic parameters, and act on different spectral ranges and propagation directions respectively, thereby avoiding optical interference cancellation between multilayer structures and improving the overall coupling efficiency and structural stability.

[0111] The fabrication method of this enhanced Micro LED display chip includes the following steps: Step 1: Construction of the first photonic crystal microstructure layer On the light-emitting surface of a blue light epitaxial structure of a Micro LED with multiple arrayed Micro LED units, a two-dimensional columnar array photonic crystal structure is constructed using a template imprinting process. The spacing between adjacent micro- and nanostructures is approximately 220 nm, which is used for local enhancement and modulation of blue light excitation. TiO2 nanospheres are then deposited according to the method in Example 1. Step 2: Fabrication of the quantum dot conversion layer Quantum dots CdSe / ZnS were mixed with UV-curable acrylic resin at a mass ratio of 1:6. The mixture was then spin-coated and UV-cured to form a quantum dot conversion layer with a thickness of approximately 1.0–2.0 μm.

[0112] Step 3: Construction of the second photonic crystal microstructure layer On the surface of the quantum dot conversion layer, a second photonic crystal microstructure layer is constructed by template imprinting. The micro-nano structure is a two-dimensional hole array structure or a groove array structure with a period of about 400 nm, which is used to enhance the emission efficiency and directionality of red or green light quantum dot emission. TiO2 nanospheres are deposited according to the method of Example 1.

[0113] Step 4: Packaging It features a multi-layer composite packaging structure, including an organosilicon buffer layer and a SiNx inorganic barrier layer.

[0114] After fabricating this enhanced Micro LED display chip into a Micro LED display device, tests showed that compared to non-photonic crystal microstructures and TiO2 nanospheres, the overall system luminous efficiency of this Micro LED display device was increased to 62% (compared to 34% for the traditional structure), the photoluminescence quantum yield of quantum dots remained above 95%, and the system color coordinates were stable. The NTSC color gamut coverage of this Micro LED display device reached 118%.

[0115] Example 6 This embodiment of the enhanced Micro LED display chip focuses on verifying the strong local enhancement effect of a 200 nm spacing between adjacent micro / nano structures on blue light excitation. The structure of this enhanced Micro LED display chip sequentially includes: a Micro LED blue light epitaxial structure, a Si3N4 photonic crystal microstructure layer, a quantum dot conversion layer, and a transparent encapsulation layer. The Si3N4 photonic crystal microstructure layer is a two-dimensional periodic columnar array + TiO2 nanosphere photonic crystal structure. The columnar array is a square or hexagonal Si3N4 nanopillar array with a period of approximately 200 nm, a column diameter of 70–110 nm, and a column height of 250–300 nm. The Si3N4 material has a high refractive index (n≈2.0), which is beneficial for forming a significant photonic bandgap and local electromagnetic field enhancement in the blue light excitation band.

[0116] The fabrication steps of this enhanced Micro LED display chip include: 1. On the light-emitting surface of the blue light epitaxial structure of Micro LED with multiple arrayed Micro LED units, a Si3N4 thin film with a thickness of approximately 120 nm is deposited by plasma-enhanced chemical vapor deposition (PECVD). 2. A two-dimensional periodic columnar array photonic crystal structure with an array period of approximately 200 nm was constructed in the Si3N4 thin film using an electron beam lithography combined with reactive ion etching process; and TiO2 nanospheres were deposited according to the method in Example 1. 3. Mix red or green quantum dots with UV-curable acrylate polymer monomers to form a quantum dot mixture, wherein the quantum dot content is 5-15 wt% of the polymer mass; 4. Spin-coat the quantum dot mixture onto the surface of the Si3N4 photonic crystal microstructure layer, and allow some of the material to penetrate into the inter-pillar array gaps; 5. Curing is performed using ultraviolet light with a wavelength of 365 nm for 2-5 minutes to form a quantum dot conversion layer with a thickness of approximately 2-5 μm; 6. Spin-coat the surface of the quantum dot conversion layer with an organosilicon encapsulation material and heat-cur it at 100°C for 30 min to form a light-transmitting encapsulation layer.

[0117] When the enhanced Micro LED display chip prepared in this embodiment is applied to a Micro LED display device, the test results show that, compared with the comparison of the non-photonic crystal microstructure and TiO2 nanospheres, the local enhancement effect of blue light is significant, the quantum dot excitation efficiency is improved by about 30%, and the device still maintains good color coordinate stability under high brightness driving conditions.

[0118] Example 7 This embodiment of the enhanced Micro LED display chip focuses on verifying the effect of a 500 nm spacing between adjacent micro / nano structures on the control of the emission path and directionality of quantum dot light. The structure of this enhanced Micro LED display chip sequentially includes: a Micro LED blue epitaxial structure, an SU-8 photonic crystal microstructure layer, a quantum dot conversion layer, and a transparent encapsulation layer. The SU-8 photonic crystal microstructure layer is a two-dimensional periodic aperture or groove array structure + TiO2 nanosphere photonic crystal structure. The aperture or groove array structure is directly constructed using the SU-8 photoresist material, with a period of approximately 500 nm, an aperture or groove width of 200-300 nm, and a structural depth of 150-200 nm. This SU-8 photonic crystal microstructure layer is mainly used to control the emission angle distribution of quantum dot light, improving photon extraction efficiency. Located above the quantum dot conversion layer, this SU-8 photonic crystal microstructure layer primarily controls the emission path and angle distribution of quantum dot light, rather than for localized enhancement of blue light excitation.

[0119] The fabrication steps of this enhanced Micro LED display chip include: 1. SU-8 photoresist is spin-coated onto the light-emitting surface of the Micro LED blue light epitaxial structure with multiple arrayed Micro LED units, with a spin-coating thickness of approximately 220 nm. 2. A two-dimensional periodic aperture array or groove array photonic crystal structure with a period of approximately 500 nm is formed in the SU-8 layer by exposure and development using ultraviolet lithography. 3. The formed SU-8 photonic crystal structure was post-baked at 95°C for 5-10 min to improve structural stability; and TiO2 nanospheres were deposited according to the method in Example 1. 4. Mix quantum dots with a UV-curable polymer, wherein the quantum dot content is 3~10 wt%, and coat the resulting quantum dot mixture onto the surface of the SU-8 photonic crystal microstructure layer; 5. Curing is performed using ultraviolet light with a wavelength of 385 nm for 3-6 minutes to form a quantum dot conversion layer with a thickness of approximately 3-6 μm; 6. Deposit a transparent inorganic encapsulation layer or spin-coat an organic silicon encapsulation layer on the surface of the quantum dot conversion layer to complete the encapsulation.

[0120] Tests showed that the enhanced Micro LED display chip prepared in this embodiment exhibited significantly improved emitted light directionality, reduced divergence angle, and an overall light extraction efficiency increase of approximately 1.5 times, making it suitable for high-brightness, wide-field-of-view Micro LED display applications.

[0121] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0122] Although this application has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of this application, and that elements of the described embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of this application to adapt particular situations or materials to the teachings of this application. Therefore, this application is not intended to be limited to the specific embodiments disclosed for carrying out this application, but rather is intended to include all embodiments falling within the scope of the appended claims.

Claims

1. An enhanced Micro LED display chip, characterized in that, Including those stacked in the thickness direction: First substrate; An LED epitaxial layer is located on the first substrate; the LED epitaxial layer includes a plurality of Micro LED units arranged in an array, the Micro LED units are electrically connected to the first substrate and can be driven independently, and the light-emitting surface of the Micro LED units faces away from the first substrate. At least one photonic crystal microstructure layer is disposed on the light-emitting surface of the Micro LED unit; the photonic crystal microstructure layer includes multiple photonic crystal microstructure units, one photonic crystal microstructure unit corresponds to one Micro LED unit, the photonic crystal microstructure unit includes periodically arranged micro / nano structures, the micro / nano structures are used to adjust the emission angle and emission area of ​​the light emitted by the Micro LED unit, the micro / nano structures also include Mie scattering microstructures composed of Mie sphere scattering particles, the micro / nano structures and Mie sphere scattering particles form a local resonance structure, which can at least form a photonic bandgap, thereby locally enhancing the light emitted by the Micro LED unit.

2. The enhanced Micro LED display chip according to claim 1, characterized in that: The micro / nano structure includes one or more combinations of groove arrays, column arrays, and hole arrays. The hole array has a pore diameter of 100-300 nm, the groove array or hole array has a depth of 150-400 nm, and the column array has a height of 150-350 nm. And / or, the thickness of the photonic crystal microstructure layer is 100~500 nm.

3. The enhanced Micro LED display chip according to claim 1, characterized in that: The micro-nano structures are arranged periodically, with a spacing of 200~500 nm between adjacent micro-nano structures.

4. The enhanced Micro LED display chip according to claim 1, characterized in that: The equivalent refractive index of the photonic crystal microstructure layer is 1.4~2.

5.

5. The enhanced Micro LED display chip according to claim 1, characterized in that: The material of the photonic crystal microstructure layer includes one or more combinations of TiO2, Si3N4, SU-8, and SiO2.

6. The enhanced Micro LED display chip according to claim 1, characterized in that: The Mie sphere scattering particles include one or more of TiO2 nanospheres, SiO2 nanospheres, Al2O3 nanospheres, and ZrO2 nanospheres; and / or, the particle size of the Mie sphere scattering particles is 50~300 nm.

7. The enhanced Micro LED display chip according to claim 1, characterized in that: A bonding layer is provided between the first substrate and the LED epitaxial layer; The Micro-LED unit includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer sequentially stacked on the first substrate; The first semiconductor layers of the plurality of Micro LED units are continuously disposed; The first substrate has a driving circuit and a plurality of driving contacts electrically connected to the driving circuit, with one driving contact corresponding to one Micro LED unit; The Micro LED unit further includes a first electrode layer located on the second semiconductor layer; The bonding layer and the LED epitaxial layer have openings that expose the driving contacts; The first electrode layer is electrically connected to the drive contact through the opening.

8. The enhanced Micro LED display chip according to claim 1, characterized in that... Also includes: A quantum dot conversion layer is disposed on the surface of the photonic crystal microstructure layer and / or embedded in the photonic crystal microstructure layer, for wavelength conversion of the light emitted by the Micro LED unit.

9. The enhanced Micro LED display chip according to claim 8, characterized in that, Also includes: A light-transparent encapsulation layer is disposed on the surface of the quantum dot conversion layer facing away from the first substrate, and the material of the light-transparent encapsulation layer includes a transparent polymer or an inorganic material. The thickness of the light-transmitting encapsulation layer is 1~50 µm.

10. The enhanced Micro LED display chip according to claim 1, characterized in that, include: Multiple photonic crystal microstructure layers, with different photonic crystal microstructure unit structures in adjacent photonic crystal microstructure layers and different spacing between adjacent micro / nano structures.

11. The enhanced Micro LED display chip according to claim 8, characterized in that, It includes: a first substrate, an LED epitaxial layer, a first photonic crystal microstructure layer, a quantum dot conversion layer, and a second photonic crystal microstructure layer, which are sequentially stacked in the thickness direction. The spacing between adjacent micro- and nanostructures in the first and second photonic crystal microstructure layers is different. The first photonic crystal microstructure layer is used to control the light emitted by the Micro LED unit, and the second photonic crystal microstructure layer is used to control the light emitted by the quantum dot conversion layer.

12. The method for fabricating the enhanced Micro LED display chip according to any one of claims 1 to 11, characterized in that, include: An LED epitaxial layer is formed on a first substrate. The LED epitaxial layer includes a plurality of Micro LED units arranged in an array. The Micro LED units are electrically connected to the first substrate and can be driven independently. The light-emitting surface of the Micro LED units faces away from the first substrate. A photonic crystal microstructure layer is formed on the light-emitting surface of the Micro LED unit. The photonic crystal microstructure layer includes multiple photonic crystal microstructure units, with one photonic crystal microstructure unit corresponding to one Micro LED unit. The photonic crystal microstructure unit contains periodically arranged micro-nano structures, allowing Mie sphere scattering particles to be deposited within the micro-nano structures to form a localized Mie resonance structure, thereby obtaining the photonic crystal microstructure layer and fabricating the enhanced Micro LED display chip.

13. The preparation method according to claim 12, characterized in that, include: At least one of the following methods is used to construct periodically arranged micro-nano structures on the light-emitting surface of the Micro LED unit: nanoimprinting, dry etching, focused ion beam, electron beam exposure, and optical interference exposure.

14. The preparation method according to claim 12, characterized in that, include: At least one capillary-assisted self-assembly method is used to deposit Mie sphere scattering particles into micro / nano structures.

15. The preparation method according to claim 12, characterized in that, include: Multiple photonic crystal microstructure layers are set up, and the photonic crystal microstructure unit structures in adjacent photonic crystal microstructure layers are different, and the spacing between adjacent micro-nano structures is different.

16. The preparation method according to claim 15, characterized in that, include: A periodically arranged micro / nano structure with a first interval is constructed on the light-emitting surface of the Micro LED unit, so that Mie sphere scattering particles are deposited in the micro / nano structure to form a first photonic crystal microstructure layer. A quantum dot conversion layer is disposed on the surface and / or inside the first photonic crystal microstructure layer; A periodically arranged micro / nano structure with a second spacing is constructed on the surface of the quantum dot conversion layer, so that Mie sphere scattering particles are deposited within the micro / nano structure to form a second photonic crystal microstructure layer. The first interval distance and the second interval distance are different.

17. The preparation method according to claim 12, characterized in that, include: A mixture of quantum dots and polymers and / or curable polymer precursors is coated onto the surface of a photonic crystal microstructure layer and / or embedded in the photonic crystal microstructure layer, and a quantum dot conversion layer is formed on the surface and / or inside the photonic crystal microstructure layer by any of the following methods: UV curing, thermal curing, or solvent evaporation film formation.

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