Quantum dot photoresist endogenous phase control structure and preparation method thereof

Abstract

The application discloses a quantum dot photoresist endogenous phase regulation structure and a preparation method thereof. The quantum dot photoresist color conversion layer is arranged above a MicroLED pixel structure, and the endogenous phase regulation structure with a height fluctuation structure and a refractive index difference is integrally formed in the quantum dot photoresist color conversion layer close to a light emitting side. The application solves the problem that the quantum dot photoresist in the prior art is only used for color conversion and needs to rely on additional optical elements to realize pixel-level optical shaping, especially solves the problem that it is difficult to high-density integrate the color conversion layer and the optical shaping layer in high-PPI MicroLED display, thereby integrating the color conversion and the pixel-level optical shaping functions in a single quantum dot photoresist layer, and the phase regulation structure and the quantum dot photoresist material are inseparable, independent diffraction optical elements can be avoided, the dependence on a microlens array or an external optical shaping layer is reduced, and the device structure is simplified.

Description

Technical Field

[0001] This invention belongs to the field of micro-light-emitting diode display and quantum dot color conversion technology, specifically relating to an intrinsic phase modulation structure in quantum dot photoresist. This invention also relates to a method for fabricating the intrinsic phase modulation structure in quantum dot photoresist. Background Technology

[0002] In MicroLED displays, quantum dot photoresist is typically used to convert the light emitted by blue MicroLEDs into red or green light to achieve full-color display. For example... Figure 1 As shown, existing quantum dot photoresists mainly perform the color conversion function of light absorption and re-emission, but they lack the ability to control the propagation direction, wavefront morphology, and spatial distribution of emitted light.

[0003] As the resolution and pixel density of MicroLED displays continue to improve, the demand for pixel-level optical shaping is gradually increasing. Traditional solutions typically introduce microlens arrays, diffractive optical elements, or other independent optical layers outside the quantum dot color conversion layer to control the direction or distribution of emitted light. However, such solutions require additional optical layers or fine microstructure fabrication, resulting in complex structures, high manufacturing costs, and significant integration challenges in high-PPI MicroLED displays.

[0004] On the other hand, during the exposure, development, and curing processes, the material distribution, surface morphology, and refractive index of quantum dot photoresists exhibit spatial differences depending on the process conditions. This material-process response characteristic provides a basis for forming phase modulation structures that are inseparable from the color conversion process within or on the surface of quantum dot photoresists.

[0005] Therefore, there is an urgent need for a solution that can integrate color conversion and pixel-level optical shaping within the quantum dot photoresist material without the introduction of independent diffraction optical elements. Summary of the Invention

[0006] The purpose of this invention is to provide an intrinsic phase modulation structure for quantum dot photoresists, which solves the problem that existing quantum dot photoresists cannot achieve color conversion and pixel-level optical shaping in an integrated manner.

[0007] Another objective of this invention is to provide a method for preparing an endogenous phase modulation structure in quantum dot photoresist.

[0008] The first technical solution adopted in this invention is: a quantum dot photoresist endogenous phase modulation structure, including a quantum dot photoresist color conversion layer disposed above the MicroLED pixel structure, wherein an endogenous phase modulation structure with a highly undulating structure and a refractive index difference is integrally formed in the quantum dot photoresist color conversion layer near the light-emitting side.

[0009] The first technical solution of this invention is further characterized by: The quantum dot photoresist color conversion layer has a quantum dot photoresist substrate on one side relative to the endogenous phase modulation structure, and the refractive index difference Δn between the endogenous phase modulation structure and the quantum dot photoresist substrate is 0.02 to 0.15.

[0010] The endogenous phase modulation structure uses quantum dot photoresist with the same matrix material as the quantum dot photoresist but with different crosslinking density or quantum dot concentration.

[0011] The height of the endogenous phase modulation structure is 0.2–2 μm.

[0012] The endogenous phase modulation structure is a periodic or quasi-periodic array with a transverse period of 0.5–3 μm.

[0013] Highly undulating structures include columnar, stepped, or lattice-like structures.

[0014] The MicroLED pixel structure includes a p-type semiconductor layer, a light-emitting layer, and an n-type semiconductor layer arranged sequentially from bottom to top. A transparent electrode layer is disposed between the n-type semiconductor layer and the quantum dot photoresist color conversion layer. The p-type semiconductor layer is electrically connected to the anode electrode in the CMOS backplane through a p-type contact electrode layer.

[0015] The second technical solution adopted in this invention is: a method for preparing an intrinsic phase modulation structure in quantum dot photoresist, comprising the following steps: Step 1: Spin-coat quantum dot photoresist onto the light-emitting side of the MicroLED pixel structure to form a quantum dot photoresist color conversion layer; Step 2: Spatially non-uniformly expose the quantum dot photoresist color conversion layer using a grayscale mask or dose modulation method to create differences in the degree of crosslinking in different regions; Step 3: The quantum dot photoresist color conversion layer that has undergone spatial non-uniform exposure is developed to dissolve the low-exposure areas and retain the high-exposure areas, forming a solid microstructure with high undulations on the surface of the quantum dot photoresist color conversion layer. Step 4: Post-bake and cure the developed quantum dot photoresist color conversion layer.

[0016] The third technical solution adopted in this invention is: a method for preparing an intrinsic phase modulation structure in quantum dot photoresist, comprising the following steps: Step 1: Spin-coat quantum dot photoresist on the light-emitting side of the MicroLED pixel structure to form a quantum dot photoresist color conversion layer and pre-bake; Step 2: Perform two separate exposures or grayscale exposures with different dosages on the pre-baked quantum dot photoresist color conversion layer to form a spatial cross-linking gradient within the quantum dot photoresist color conversion layer; Step 3: Perform differential heat treatment on the quantum dot photoresist color conversion layer that forms a spatial cross-linking gradient, so that a temperature difference is formed in a local area of ​​the quantum dot photoresist color conversion layer, and the cross-linking density inside the quantum dot photoresist color conversion layer forms a gradient distribution.

[0017] The fourth technical solution adopted in this invention is: a method for preparing an intrinsic phase modulation structure in quantum dot photoresist, comprising the following steps: Step 1: Spin-coat quantum dot photoresist on the light-emitting side of the MicroLED pixel structure to form a quantum dot photoresist color conversion layer and pre-bake; Step 2: Perform the first exposure of the pre-baked quantum dot photoresist color conversion layer using a grayscale mask to define the degree of crosslinking in different regions; Step 3: Control the solvent diffusion time of the quantum dot photoresist color conversion layer after the first exposure to create a concentration gradient distribution of quantum dots in a local area; Step 4: Perform overall exposure and development on the quantum dot photoresist color conversion layer that generates a concentration gradient distribution to form a spatial composition difference structure and then bake and cure it.

[0018] The beneficial effects of this invention are as follows: The quantum dot photoresist intrinsic phase modulation structure and its preparation method of this invention, by intrinsically forming a phase modulation structure during the quantum dot photoresist forming process, enable the quantum dot photoresist to perform pixel-level shaping of its own emitted light wavefront after color conversion, thereby improving the effectiveness of wavefront control. This solves the problem in the prior art where quantum dot photoresist is only used for color conversion and requires additional optical components to achieve pixel-level optical shaping. In particular, it solves the problem of difficulty in high-density integration of the color conversion layer and the optical shaping layer in high-PPI MicroLED displays. Thus, color conversion and pixel-level optical shaping functions are integrated into a single quantum dot photoresist layer. Moreover, the phase modulation structure is inseparable from the quantum dot photoresist material, avoiding the introduction of independent diffraction optical elements, reducing dependence on microlens arrays or external optical shaping layers, and simplifying the device structure. This invention is applicable to the pixel-level optical control requirements of high-PPI MicroLED displays and can improve the optical consistency and long-term reliability of the display system. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a traditional quantum dot photoresist; Figure 2 This is a schematic diagram of the intrinsic phase modulation structure of the quantum dot photoresist of the present invention; Figure 3 This is a schematic diagram of another quantum dot photoresist endogenous phase modulation structure of the present invention; Figure 4 This is a top view schematic diagram of another quantum dot photoresist endogenous phase modulation structure of the present invention.

[0020] In the image, 1. CMOS backplane, 2. MicroLED pixel structure, 3. transparent electrode layer, 4. quantum dot photoresist color conversion layer; 11. Anode electrode; 12. Cathode electrode; 21. n-type semiconductor layer; 22. light-emitting layer; 23. p-type semiconductor layer; 24. p-type contact electrode layer; 41. Endogenous phase modulation structure. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0022] Example 1 This invention provides an endogenous phase modulation structure for quantum dot photoresist, which is directly formed during the formation of quantum dot photoresist (QDPR) and is intrinsically solidified inside the QDPR or its near-light-emitting surface region, constituting a solid microstructure with a defined geometric morphology and optical modulation capability.

[0023] The phase modulation structure is a three-dimensional micro / nano structure unit composed of highly cross-linked quantum dot photoresist material. It differs from the surrounding low-cross-linked regions in refractive index and morphology, thus spatially forming an optical structure with a defined phase delay capability. The structure is not simply limited by shape, but rather satisfies the following physical constraints: it has continuous or segmented height undulations in the light emission direction, and the combination of its height difference Δh and local refractive index difference Δn satisfies a preset optical path modulation condition Δ(n·h), used to achieve controllable modulation of the emitted light wavefront.

[0024] Example 2 This invention provides an intrinsic phase modulation structure for quantum dot photoresist, with the following characteristic dimensions and parameter ranges: the lateral period of the structure is 0.5–3 μm, preferably 0.8–2 μm; the structure height is 0.2–2 μm, preferably 0.5–1.5 μm; the structure duty cycle is 30%–70%; and the refractive index difference Δn between the structure region and the QDPR substrate is 0.02–0.15. Through the combination of these parameters, a single structural unit can provide a phase modulation capability of approximately 0.2π–1.5π, forming continuous or partitioned wavefront modulation effects at the pixel scale.

[0025] In terms of structural morphology, phase-modulated structures can manifest as periodic or quasi-periodic arrays, but their key limitation is that the structural units form a continuous or discrete phase distribution with a definite height distribution function in space, rather than a random scattering structure. Specifically, columnar, stepped, or lattice structures can be adopted, but their height along the planar direction must meet a preset gradient change or zonal change relationship, for example, there is a height difference of 10% to 50% between the central region and the edge region, in order to achieve wavefront redistribution.

[0026] The phase modulation structure is formed through a double exposure and development process using quantum dot photoresist. Specifically, a first exposure is performed with an exposure dose of 120–200 mJ / cm². 2 A partially cross-linked latent image structure is formed inside the QDPR; subsequently, grayscale exposure or double exposure (dose 200–350 mJ / cm²) is performed. 2 Differential energy input is applied to different regions to create a gradient distribution of cross-linking levels. During development, low-cross-linked regions dissolve preferentially, while high-cross-linked regions remain, thus forming solid microstructures with height differences inside or on the surface of the QDPR. The development time is 40–80 seconds, followed by curing at 100℃–130℃ to stabilize the structure.

[0027] At the material level, the structure is entirely composed of a quantum dot photoresist system. The refractive index difference comes from the difference in crosslinking density (typically ranging from about 0.02 to 0.08), or is further enhanced by local quantum dot concentration changes (5% to 20% concentration difference), thereby improving the phase modulation capability.

[0028] In optical applications, the phase modulation structure acts on the emitted light from the quantum dot, and its modulation mechanism is based on the phase delay difference Δφ caused by the local optical path difference Δ(n·h). By controlling the structure height and refractive index distribution, the emitted light at different spatial locations can have different phases upon exiting, thereby achieving wavefront shaping, intensity redistribution, or divergence angle optimization.

[0029] Simulation results show that, with a structure height of approximately 1 μm, a period of approximately 1.5 μm, and Δn ≈ 0.05, a phase modulation capability of approximately 0.8π to 1.2π can be achieved, improving the uniformity of the light intensity distribution of the pixel emitted light by approximately 20% to 35%, while reducing the divergence angle by approximately 10% to 25%. Experimental tests show that, under continuous operating conditions, this endogenous structure does not introduce additional interface failures, and its optical function remains consistent with that of the color conversion layer.

[0030] By using the aforementioned endogenous phase modulation structure with a clear material composition, geometric parameter range, and process implementation path, reproducible wavefront modulation function within the quantum dot photoresist is achieved, while avoiding the interface complexity and reliability issues caused by external optical components.

[0031] Example 3 This invention provides an intrinsic phase modulation structure for quantum dot photoresists, such as... Figures 2 to 4 As shown, it includes a CMOS backplane 1, a MicroLED pixel structure 2 disposed on the CMOS backplane 1, a transparent electrode layer 3 electrically connected to the MicroLED pixel structure 2, and a quantum dot photoresist color conversion layer 4 disposed on the light-emitting side of the MicroLED pixel structure 2.

[0032] The CMOS backplane 1 integrates a driving circuit and is electrically connected to the MicroLED pixel structure 2 through conductive vias and metal interconnect structures. The CMOS backplane 1 is connected to the MicroLED pixel through an anode electrode 11 and a cathode electrode 12. The MicroLED pixel structure 2 includes an epitaxially formed n-type semiconductor layer 21, a light-emitting layer 22, and a p-type semiconductor layer 23, and is connected to the anode electrode 11 of the CMOS backplane 1 through a bottom p-type contact electrode layer 24 to form a driving circuit.

[0033] The transparent electrode layer 3 is a transparent conductive layer disposed on the light-emitting side of the MicroLED, used for current spread and allowing light emission to pass through. The transparent conductive layer covers the light-emitting surface of the MicroLED pixel and is substantially aligned with the pixel area in the planar direction.

[0034] A quantum dot photoresist color conversion layer 4 is disposed on top of the transparent conductive layer and corresponds to the MicroLED pixel in a planar position. It is used to receive the excitation light emitted by the MicroLED and realize wavelength conversion. The quantum dot photoresist color conversion layer 4 covers the main light-emitting area of ​​the MicroLED pixel in the thickness direction and forms direct contact with the underlying transparent conductive layer or is connected through an interface layer.

[0035] An endogenous phase modulation structure 41 is formed inside the quantum dot photoresist color conversion layer 4 or in a region near the light-emitting side. The phase modulation structure 41 is formed by patterning the quantum dot photoresist material itself, and its material composition is an integral structure with the quantum dot photoresist color conversion layer 4, without any independent interface or additional layer.

[0036] In terms of spatial distribution, the endogenous phase modulation structure 41 is located in the upper region of the quantum dot photoresist color conversion layer 4. Its bottom is continuously connected to the unpatterned quantum dot photoresist substrate, and its top forms an undulating structural surface. The structure covers the light-emitting area of ​​the corresponding MicroLED pixel in the planar direction and can be arranged continuously or in a distributed manner within the pixel boundary.

[0037] The endogenous phase modulation structure 41 forms a height difference relative to the quantum dot photoresist substrate in the thickness direction. Its structural height is non-uniformly distributed along the planar direction and forms multiple local undulating structures at different positions. The undulating structures can be formed by local cross-linking differences, and their morphology is an irregular columnar or stepped continuous structure.

[0038] Structurally, the light emitted from the MicroLED pixel structure 2 enters the quantum dot photoresist color conversion layer 4 through the transparent electrode layer 3, where wavelength conversion is completed, and then propagates further to the endogenous phase modulation structure 41 region. The endogenous phase modulation structure 41 is located at the upstream end of the light propagation path, and its output surface constitutes the outermost interface of the entire pixel light-emitting structure.

[0039] Through the above structural arrangement, the quantum dot photoresist color conversion layer 4 can simultaneously undertake the functions of color conversion and wavefront modulation. The endogenous phase modulation structure 41, as the endogenous structural unit of this layer, is stacked sequentially with the MicroLED pixel structure 2 in the vertical direction and is set in the planar direction corresponding to the pixel area.

[0040] In this embodiment, the endogenous phase modulation structure 41 does not exist as an independent optical device, but is embedded inside the quantum dot photoresist color conversion layer 4 and forms an integral part thereto, thereby achieving pixel-level optical modulation function while maintaining structural continuity.

[0041] Example 4 This invention provides a method for fabricating an endogenous phase modulation structure using quantum dot photoresist. In this embodiment, a quantum dot photoresist layer is formed on the light-emitting side of a MicroLED pixel, and a phase modulation structure is endogenously formed on its surface through exposure response differences. The MicroLED pixel has a size of 8μm × 8μm and a pixel pitch of 4μm. A color conversion layer with a thickness of 5–7μm is formed by spin-coating quantum dot photoresist onto the pixel.

[0042] In photolithography, structure formation is achieved by introducing spatially non-uniform exposure conditions. Specifically, grayscale masks or dose-modulated exposure methods are used to adjust the exposure dose in different regions to range from 120 to 300 mJ / cm². 2 Variations occur within a certain range. After exposure, a development process of 50–70 seconds is performed, which preferentially dissolves the low-exposure areas and preserves the high-exposure areas, thereby forming a solid microstructure with high undulations on the surface of the quantum dot photoresist.

[0043] The formed surface structure has a height of 0.4–1.2 μm, a lateral feature size preferably of 0.3–0.8 μm, more preferably 0.4–0.7 μm, and a structural spacing of 0.5–1.5 μm. These lateral feature sizes match the red light emission band, making it suitable for phase modulation of red light emitted by quantum dots in the 620 nm–650 nm range. Due to differences in cross-linking degree, a refractive index difference of approximately 0.03–0.08 is formed between this structural region and the substrate, thereby creating effective optical path modulation at the light emission interface.

[0044] In terms of process implementation, an i-line lithography machine is used for exposure, with an exposure time of 3–8 seconds. Dosage distribution is controlled by adjusting the local transmittance (20%–80%) or by stacking multiple exposures. After development, the structure is post-baked at 110℃–130℃ for 3–5 minutes to stabilize and solidify it.

[0045] In terms of optical effects, the structure modulates the phase of the emitted light from the quantum dot through a local optical path difference Δ(n·h). Under typical parameter conditions, when the structure height is approximately 0.8 μm, the refractive index difference Δn≈0.05, and the lateral feature size is approximately 0.5–0.6 μm, a phase modulation capability of approximately 0.6π–1.0π can be achieved.

[0046] Based on optical simulation results, this structure can improve the uniformity of light intensity distribution of pixel emitted light by about 15% to 30% and reduce the divergence angle by about 10% to 20%. In experimental tests, compared with the unstructured sample, the brightness uniformity is improved by about 18%, the edge light intensity is reduced by about 20%, and no additional interface failure is introduced.

[0047] By utilizing the endogenous phase structure formed by the difference in exposure response, wavefront modulation within the quantum dot photoresist layer is achieved without additional processing steps, making it suitable for optical shaping applications of red quantum dot color conversion pixels.

[0048] Example 5 This invention provides a method for preparing an endogenous phase modulation structure of quantum dot photoresist. In this embodiment, a quantum dot photoresist (QDPR) color conversion layer is formed above a MicroLED pixel. By adjusting the temperature, time and exposure dose during the curing process, the QDPR forms a difference in the degree of crosslinking in the thickness direction and local areas, thereby forming a stable refractive index distribution structure inside the material to achieve phase modulation of emitted light.

[0049] The MicroLED pixel size is 8μm × 8μm, corresponding to a QDPR layer thickness of 5–7μm. During the curing process, the spin-coated QDPR is first pre-baked (90℃, 2 min), followed by zoned exposure or grayscale exposure processing, with the first exposure dose being 120–180 mJ / cm². 2 Used to form the basic cross-linked structure; the second exposure dose is 220–320 mJ / cm. 2 The degree of cross-linking is enhanced within a selected region, thereby forming a spatial cross-linking gradient.

[0050] In the post-curing stage, further control is achieved through differentiated heat treatment: staged post-baking is performed within the range of 100℃ to 130℃, with local areas using masks or local heating to create temperature differences (approximately 10℃ to 30℃), and the curing time is 3 to 8 minutes. Through the synergistic effect of the above exposure and heat treatment, a gradient distribution of crosslinking density is formed within the QDPR, with a corresponding refractive index variation range of approximately Δn≈0.02 to 0.06.

[0051] In terms of structural performance, the refractive index gradient is distributed along the thickness direction or in local lateral regions, corresponding to an equivalent optical path difference Δ(n·t) of approximately 0.05–0.3 μm, which can provide a phase modulation capability of approximately 0.2π–1.0π.

[0052] Based on optical simulation results, under the conditions of a QDPR thickness of 6 μm and Δn≈0.04, the wavefront error of the pixel emitted light can be reduced by approximately 30%–55%, and the uniformity of light intensity distribution can be improved by approximately 15%–25%. Experimental tests show that under continuous operating conditions (current density approximately 50 A / cm²), the effect is achieved. 2 This structure does not introduce additional interface defects and improves brightness uniformity by approximately 12% to 18%.

[0053] By using the internal refractive index modulation structure formed by the difference in curing conditions, the phase modulation function inside the quantum dot photoresist is realized without the need to introduce an additional structural layer. It features simple process, integrated structure and good reliability.

[0054] Example 6 This invention provides a method for fabricating an endogenous phase-modulation structure using quantum dot photoresist. In this embodiment, a quantum dot photoresist color conversion layer is formed on the light-emitting side of a MicroLED pixel. By introducing differences in material composition distribution within this layer, an endogenous phase-modulation structure is formed. By adjusting the quantum dot concentration and substrate material ratio, the quantum dot photoresist forms regions with different equivalent refractive indices in the planar direction, thereby achieving wavefront modulation of emitted light while maintaining a relatively smooth surface morphology (surface undulation <0.2μm).

[0055] MicroLED pixels have a size of 8μm × 8μm, and the quantum dot photoresist layer thickness is approximately 5–7μm. Through patterned exposure and material ratio control, the quantum dot photoresist creates a compositional difference between the central and edge regions within the pixel. Specifically, the quantum dot volume fraction in the central region is 20%–30%, corresponding to an equivalent refractive index of approximately 1.62–1.68; while the quantum dot volume fraction in the edge region is 10%–15%, corresponding to an equivalent refractive index of approximately 1.54–1.60, thus forming a refractive index difference of Δn≈0.05–0.10.

[0056] The material distribution structure was achieved through a double exposure and local diffusion control process. Specifically, firstly, a QDPR film with a thickness of approximately 6 μm was formed by spin coating (2500–3000 rpm, 30–40 s) and pre-baking (90°C, 2 min); then, the first exposure was performed using a grayscale mask (dose 120–180 mJ / cm²). 2 The degree of cross-linking in different regions is defined; before development, the concentration gradient distribution of quantum dots in local areas is created by controlling the solvent diffusion time (30-60 s); then, overall exposure (200-300 mJ / cm²) is performed. 2 The process involves developing the material (40–70 s) to form a structure with spatial compositional differences; finally, it undergoes post-baking (110°C–130°C, 5 min) to complete the curing process.

[0057] In this structure, the different concentrations of quantum dots and the different densities of the matrix in different regions lead to a controllable change in the local refractive index, thereby forming an equivalent optical path difference Δ(n·t) during light propagation and achieving modulation of the emitted light wavefront.

[0058] Based on optical simulation results, under the conditions of Δn≈0.06 and film thickness of about 6μm, a phase modulation capability of about 0.6π to 1.0π can be achieved, which improves the uniformity of light intensity distribution of pixel emitted light by about 15% to 30% and reduces the divergence angle by about 8% to 20%. In experimental testing, no obvious phase separation or optical performance degradation was observed after 100 hours of continuous operation, and the brightness uniformity was improved by about 18% compared with a homogeneous material structure.

[0059] By employing the aforementioned endogenous phase modulation method based on material composition distribution, controllable wavefront shaping within quantum dot photoresist is achieved without introducing additional interfaces or significant morphological structures. This method is suitable for MicroLED display applications with high requirements for surface flatness and process compatibility.

Claims

1. A quantum dot photoresist intrinsic phase modulation structure, characterized in that, The structure includes a quantum dot photoresist color conversion layer (4) disposed above the MicroLED pixel structure (2). An endogenous phase control structure (41) with a highly undulating structure and a refractive index difference is integrally formed in the quantum dot photoresist color conversion layer (4) near the light-emitting side. The side of the quantum dot photoresist color conversion layer (4) opposite to the endogenous phase control structure (41) is a quantum dot photoresist substrate. The refractive index difference Δn between the endogenous phase control structure (41) and the quantum dot photoresist substrate is 0.02 to 0.

15. The endogenous phase control structure (41) uses quantum dot photoresist with the same material as the quantum dot photoresist substrate but with different crosslinking density or quantum dot concentration. The MicroLED pixel structure (2) includes a p-type semiconductor layer (23), a light-emitting layer (22) and an n-type semiconductor layer (21) arranged sequentially from bottom to top. A transparent electrode layer (3) is provided between the n-type semiconductor layer (21) and the quantum dot photoresist color conversion layer (4). The p-type semiconductor layer (23) is electrically connected to the anode electrode (11) in the CMOS backplane (1) through the p-type contact electrode layer (24).

2. The quantum dot photoresist intrinsic phase modulation structure as described in claim 1, characterized in that, The height of the endogenous phase modulation structure (41) is 0.2–2 μm.

3. The quantum dot photoresist intrinsic phase modulation structure as described in claim 1, characterized in that, The endogenous phase modulation structure (41) is a periodic or quasi-periodic array with a transverse period of 0.5 to 3 μm.

4. The quantum dot photoresist intrinsic phase modulation structure as described in claim 1 or 3, characterized in that, The height undulation structure includes columnar, stepped, or lattice structures.

5. The method for fabricating an intrinsic phase modulation structure in quantum dot photoresist as described in claim 1, characterized in that, Includes the following steps: Step 1: Spin-coat quantum dot photoresist onto the light-emitting side of the MicroLED pixel structure to form a quantum dot photoresist color conversion layer; Step 2: Spatially non-uniformly expose the quantum dot photoresist color conversion layer using a grayscale mask or dose modulation method to create differences in the degree of crosslinking in different regions; Step 3: The quantum dot photoresist color conversion layer that has undergone spatial non-uniform exposure is developed to dissolve the low-exposure areas and retain the high-exposure areas, forming a solid microstructure with high undulations on the surface of the quantum dot photoresist color conversion layer. Step 4: Post-bake and cure the developed quantum dot photoresist color conversion layer.

6. The method for preparing the intrinsic phase modulation structure of quantum dot photoresist as described in claim 1, characterized in that, Includes the following steps: Step 1: Spin-coat quantum dot photoresist on the light-emitting side of the MicroLED pixel structure to form a quantum dot photoresist color conversion layer and pre-bake; Step 2: Perform two separate exposures or grayscale exposures with different dosages on the pre-baked quantum dot photoresist color conversion layer to form a spatial cross-linking gradient within the quantum dot photoresist color conversion layer; Step 3: Perform differential heat treatment on the quantum dot photoresist color conversion layer that forms a spatial cross-linking gradient, so that a temperature difference is formed in a local area of ​​the quantum dot photoresist color conversion layer, and the cross-linking density inside the quantum dot photoresist color conversion layer forms a gradient distribution.

7. The method for fabricating an intrinsic phase modulation structure in quantum dot photoresist as described in claim 1, characterized in that, Includes the following steps: Step 1: Spin-coat quantum dot photoresist on the light-emitting side of the MicroLED pixel structure to form a quantum dot photoresist color conversion layer and pre-bake; Step 2: Perform the first exposure of the pre-baked quantum dot photoresist color conversion layer using a grayscale mask to define the degree of crosslinking in different regions; Step 3: Control the solvent diffusion time of the quantum dot photoresist color conversion layer after the first exposure to create a concentration gradient distribution of quantum dots in a local area; Step 4: Perform overall exposure and development on the quantum dot photoresist color conversion layer that generates a concentration gradient distribution to form a spatial composition difference structure and then bake and cure it.

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