Nanoimprint process for improving uniform distribution of nanoscale quantum dot light-emitting units

Abstract

The invention discloses a nanoimprint process for improving uniform distribution of nanoscale quantum dot light-emitting units, and relates to the field of photoelectric display. According to the process, through the steps of substrate interface treatment, quantum dot composite imprinting glue preparation, gluing imprinting and curing demolding, high-uniformity distribution and lossless demolding of quantum dot light-emitting units are achieved. Wherein the quantum dot composite imprinting adhesive comprises an amphiphilic structuring agent, a fluorine-containing surfactant and elastic stress buffer microspheres, and in the imprinting process, the amphiphilic structuring agent realizes rapid filling through shear thinning and reconstructs a network to lock the positions of quantum dots; during curing, the fluorine-containing surfactant migrates to form an interface slip layer, and the elastic microspheres disperse stress. The process solves the problems of quantum dot migration agglomeration and demolding damage, and the prepared quantum dot pattern is small in distribution uniformity variation coefficient and low in edge tearing defect density, and has extremely high industrial application value.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic displays, and in particular to a nanoimprinting process for improving the uniformity of the distribution of nanoscale quantum dot light-emitting units. Background Technology

[0002] Quantum dot materials are considered ideal candidates for next-generation high-density display technology due to their high color purity, good color saturation, and solution-processability. Nanoimprint lithography technology is widely used in the fabrication of quantum dot pixel arrays due to its high resolution, low cost, and large-area processing capabilities.

[0003] Quantum dot nanoimprint technology is key to realizing quantum dot color conversion arrays for next-generation high-definition displays. However, this process has long faced two major technical bottlenecks:

[0004] Uniformity of distribution challenge: During the process of filling micro-nano cavities with imprinting adhesive, quantum dots, as nanoparticles, are prone to migration and aggregation due to the mismatch between their rheological behavior and that of the polymer matrix, resulting in the "coffee ring effect" or local enrichment, leading to uneven light emission and color deviation.

[0005] Demolding damage problem: After curing, the interfacial adhesion force between the colloid and the nanoimprint template is often greater than the cohesive force of the colloid itself or the adhesion force with the substrate, resulting in stress concentration during demolding, causing pattern tearing, quantum dot quenching, and a sharp drop in yield.

[0006] Existing technologies often address one problem in isolation, such as optimizing only the template anti-stick layer or adjusting the imprinting parameters, without systematically and synergistically controlling the material system and physicochemical processes, resulting in limited effectiveness. Summary of the Invention

[0007] In view of some shortcomings of existing technologies, the present invention aims to provide a nanoimprinting process that improves the uniformity of the distribution of quantum dot luminescent units at the nanoscale. This process utilizes amphiphilic structuring agents to achieve "intelligent rheology" while ensuring high filling capacity and high stability. The introduction of stress-buffered microspheres as embedded "micro-dampers" effectively solves the tearing problem caused by stress concentration. Through the spontaneous migration of fluorinated surfactants at the interface, a "synergistic" ultra-slippery release interface is formed with the external template anti-adhesion layer.

[0008] To achieve the above objectives, in a first aspect of the present invention, a nanoimprinting process is provided to improve the uniformity of the distribution of quantum dot luminescent units at the nanoscale, the process comprising the following steps:

[0009] S1: Substrate interface treatment, forming an interface layer on the substrate surface to enhance adhesion;

[0010] S2: Prepare quantum dot composite imprinting adhesive by dispersing quantum dots, amphiphilic structurers, fluorinated surfactants and elastic stress buffer microspheres in an imprinting adhesive matrix to form a quantum dot composite imprinting adhesive with shear thinning properties.

[0011] S3: Coating and Imprinting: The quantum dot composite imprinting adhesive is coated onto the treated substrate, and imprinting is performed using a nanoimprinting template at a set temperature and pressure.

[0012] S4: Curing and demolding, the quantum dot composite imprinting adhesive is cured under imprinting conditions, and then the nanoimprinting template is separated from the cured adhesive;

[0013] In step S3, during the imprinting process, the amphiphilic structuring agent reduces the viscosity of the colloid under shear force to achieve rapid filling. After the pressure stabilizes, its three-dimensional network structure is rapidly reconstructed to lock the quantum dot positions. Meanwhile, in step S4, during the curing process, the fluorinated surfactant spontaneously migrates to the colloid-template interface to form a slip layer, and the elastic stress buffer microspheres disperse stress inside the cured colloid, together achieving non-destructive demolding with a peel force of less than 3 mN / cm.

[0014] In one specific embodiment, the amphiphilic structuring agent is hydrogenated castor oil or polyamide wax, and its mass percentage in the quantum dot composite imprinting adhesive is 0.5% to 2%.

[0015] In one specific embodiment, the elastic stress-buffering microspheres are silicone microspheres with an average particle size of 100 nm to 500 nm, and their mass percentage in the quantum dot composite imprinting adhesive is 1% to 3%.

[0016] In one specific embodiment, the fluorinated surfactant and the anti-stick layer on the surface of the nanoimprint template together constitute a gradient-decreasing interfacial energy system, wherein the surface energy of the interfacial slip layer is lower than the surface energy of the anti-stick layer.

[0017] In one specific embodiment, the interface treatment of the substrate is to spin-coat a layer of silane coupling agent, which forms a chemical bond with the substrate surface and forms a chemical crosslink with the cured imprint adhesive.

[0018] In one specific embodiment, the quantum dot composite imprinting adhesive further includes a quantum dot-specific dispersant, which is a block copolymer with an anchoring group at one end anchored to the surface of the quantum dots and a polymer chain segment compatible with the imprinting adhesive matrix at the other end.

[0019] In one specific embodiment, the quantum dot pattern prepared by the process has a quantum dot distribution uniformity variation coefficient of less than ±3% and a pattern edge tearing defect density of less than 50 defects / cm². 2 .

[0020] In one specific embodiment, the process includes the following steps:

[0021] Step SA: On the back side of the substrate, a matrix-arranged Wheatstone bridge array is fabricated using a photolithography process;

[0022] Step SB: During the imprinting and holding pressure stage, real-time pressure monitoring is performed, and the imprinting pressure state of the entire board is adjusted. Among them, the pressure distribution data of the entire board is collected through the Wheatstone bridge array on the back, and the distributed piezoelectric actuators on the imprinting head are controlled by the algorithm to achieve dynamic and local fine-tuning of pressure to ensure the pressure uniformity of the entire board.

[0023] Step SC: After step S4, the Wheatstone bridge array on the back side of the substrate is removed by selective wet etching; after etching, it is cleaned and dried to obtain a clean final display device.

[0024] The beneficial effects of this invention are as follows: 1) This invention combines rheological control (kinetics) with interfacial energy engineering (thermodynamics), systematically rather than in isolation solving the distribution and tearing problems. It uses an amphiphilic structuring agent to achieve "intelligent rheology" while ensuring high filling capacity and high stability. The introduction of stress-buffered microspheres as embedded "micro-dampers" effectively solves the tearing caused by stress concentration. Through the spontaneous migration of the interface using fluorinated surfactants, a "synergistic" super-slippery release interface is formed with the external template anti-stick layer. This invention's technical solution results in a defect rate reduction of over 95% and near-lossless quantum dot efficiency maintenance; this leap in performance is the most direct manifestation of creativity. 2) Synergy: The organic combination of rheological dynamics control and interfacial / bulk force management forms a closed-loop solution, rather than a piecemeal approach. 3) High uniformity: Through a "dynamic viscosity reduction-instantaneous locking" mechanism and a dedicated dispersant, the quantum dot distribution uniformity (coefficient of variation) is improved from ±15% in traditional processes to within ±3%. 4) Non-destructive: Through the synergy of the "interface slip layer + internal stress buffer microspheres", the demolding peel force is reduced to below 3N / m, the density of tearing defects at the pattern edge is reduced by more than 95%, and the quantum dot photoluminescence quantum efficiency is maintained at more than 98%. 5) Industrialization value: All functional components are introduced through blending, requiring no additional processing steps. Large-area production yield can reach over 99.5%, demonstrating extremely high prospects for mass production applications. 6) This invention achieves real-time monitoring of the entire board pressure through a back-side Wheatstone bridge array, improving the uniformity of the imprinting process. Attached Figure Description

[0025] Figure 1 This is a flowchart of a nanoimprinting process for improving the uniformity of the distribution of quantum dot light-emitting units at the nanoscale, as provided in the first embodiment of the present invention. Detailed Implementation

[0026] The embodiments of this patent are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this patent, and should not be construed as limiting this patent.

[0027] In the description of this patent, it should be understood that the terms “center,” “upper,” “lower,” “front,” “back,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this patent and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this patent.

[0028] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] Example 1

[0031] Analysis reveals that the uneven distribution of quantum dots and pattern tearing are essentially due to the uncontrolled physicochemical processes described below: (1) Uneven flow: As nanoparticles, quantum dots migrate at different speeds due to rheological mismatch when the imprinting adhesive fills the template cavity, resulting in the "coffee ring effect" or localized agglomeration. (2) Stress concentration: During demolding, the adhesion force between the cured adhesive and the template is greater than the cohesive force of the adhesive itself or the adhesion force with the substrate, causing stress to be concentrated and released at the fragile quantum dot aggregation points, resulting in tearing. In this embodiment, the above problems are addressed through a multi-dimensional organic combination.

[0032] like Figure 1 As shown, the first embodiment of the present invention provides a nanoimprinting process for improving the uniformity of the distribution of quantum dot light-emitting units at the nanoscale, the process comprising the following steps:

[0033] S1: Substrate interface treatment, forming an interface layer on the substrate surface to enhance adhesion;

[0034] S2: Prepare quantum dot composite imprinting adhesive by dispersing quantum dots, amphiphilic structurers, fluorinated surfactants and elastic stress buffer microspheres in an imprinting adhesive matrix to form a quantum dot composite imprinting adhesive with shear thinning properties.

[0035] Regarding amphiphilic structurers

[0036] Material selection: Add 0.5%-2% hydrogenated castor oil or polyamide wax to the imprinting adhesive. These materials form a three-dimensional nanofiber network structure in a static state, giving the colloid extremely high thixotropic properties.

[0037] The mechanism of action is as follows: (1) Shear thinning: Under high pressure (50-100 bar) during imprinting, the three-dimensional network is destroyed, and the viscosity of the colloidal substance decreases rapidly and instantaneously, achieving rapid and bubble-free filling. (2) Instantaneous recovery: Once the pressure stabilizes or is released, the nanofiber network is rapidly rebuilt within 1-3 seconds, and the viscosity is restored. This effectively locks the position of the quantum dots, preventing them from redistributing due to Brownian motion or convection during the pressure holding stage, fundamentally eliminating the "coffee ring effect".

[0038] Regarding stress-buffering microspheres

[0039] Material introduction: Mix 1-3% of elastic organosilicon microspheres (diameter ~100-500nm) into the imprinting adhesive.

[0040] Mechanism of action: These microspheres are uniformly distributed in the cured colloid. When demolding stress is generated and transmitted, these soft microspheres can act as tiny "stress buffers," absorbing and dispersing concentrated stress through their own elastic deformation, thus preventing the initiation and propagation of microcracks.

[0041] Beneficial effects: It provides special protection for the pattern edges and quantum dot enrichment areas, achieving an ultra-low peel force of <3mN / cm, and reducing the edge tearing rate by more than 95%.

[0042] S3: Coating and Imprinting: The quantum dot composite imprinting adhesive is coated onto the treated substrate, and imprinting is performed using a nanoimprinting template at a set temperature and pressure.

[0043] S4: Curing and demolding, the quantum dot composite imprinting adhesive is cured under imprinting conditions, and then the nanoimprinting template is separated from the cured adhesive;

[0044] In step S3, during the imprinting process, the amphiphilic structuring agent reduces the viscosity of the colloid under shear force to achieve rapid filling. After the pressure stabilizes, its three-dimensional network structure is rapidly reconstructed to lock the quantum dot positions. Meanwhile, in step S4, during the curing process, the fluorinated surfactant spontaneously migrates to the colloid-template interface to form a slip layer, and the elastic stress buffer microspheres disperse stress inside the cured colloid, together achieving non-destructive demolding with a peel force of less than 3 mN / cm.

[0045] Preferably, the amphiphilic structuring agent is hydrogenated castor oil or polyamide wax, and its mass percentage in the quantum dot composite imprinting adhesive is 0.5% to 2%.

[0046] Preferably, the elastic stress-buffering microspheres are silicone microspheres with an average particle size of 100 nm to 500 nm, and their mass percentage in the quantum dot composite imprinting adhesive is 1% to 3%.

[0047] In order to benefit the glass, in this embodiment, the interaction forces of each interface are systematically managed during demolding.

[0048] Ideal demolding requirements: colloid-substrate adhesion force > colloid cohesive force > colloid-template adhesion force.

[0049] Preferably, a layer of silane coupling agent is pre-spin-coated onto the substrate. One end of the molecule forms a chemical bond with the substrate (such as ITO / glass), and the other end contains acrylate or epoxy groups, which can participate in the curing reaction of the imprinting adhesive to form a strong chemical bond.

[0050] Optimize the cohesive strength of the colloid: Use gradient curing or flexible crosslinking agent technology to make the cured colloid itself highly tough and able to withstand demolding stress without breaking from the inside.

[0051] Extremely reduced template adhesion: A fluorinated surfactant is incorporated into the imprinting adhesive on top of the template anti-stick layer (such as perfluorosilane). During imprinting and curing, this fluorinated component, due to its extremely low surface energy, spontaneously migrates to the colloid-template interface, forming a molecular-level "super-slip layer," minimizing peel force.

[0052] Preferably, the fluorinated surfactant and the anti-stick layer on the surface of the nanoimprint template together constitute a gradient-decreasing interfacial energy system, wherein the surface energy of the interfacial slip layer is lower than the surface energy of the anti-stick layer.

[0053] Preferably, the interface treatment of the substrate is to spin-coat a layer of silane coupling agent, which forms a chemical bond with the substrate surface and forms a chemical crosslink with the cured imprint adhesive.

[0054] Preferably, the quantum dot composite imprinting adhesive further comprises a quantum dot-specific dispersant, which is a block copolymer with an anchoring group at one end anchored to the surface of the quantum dots and a polymer chain segment compatible with the imprinting adhesive matrix at the other end.

[0055] Regarding quantum dot-specific dispersants

[0056] Material design: Synthesize a block copolymer dispersant with an anchoring group (such as a carboxyl group or a phosphonic acid group, which strongly binds to the quantum dot surface) at one end and a compatible segment (such as a polyacrylate, which is compatible with the imprinting adhesive matrix) at the other end.

[0057] Mechanism of action: This dispersant forms a stable polymer protective layer on the surface of quantum dots through steric hindrance, preventing them from agglomerating in polymer colloids due to van der Waals forces.

[0058] Beneficial effect: The quantum dots maintain a monodisperse state throughout the colloidal storage and flow process.

[0059] Preferably, the quantum dot pattern prepared by the process has a quantum dot distribution uniformity variation coefficient of less than ±3% and a pattern edge tearing defect density of less than 50 defects / cm². 2 .

[0060] Working principle: This embodiment fundamentally solves the above-mentioned problems through innovative material composition and synergistic process of nanoimprint technology. Its core lies in: in the imprint filling stage, "dynamic filling and static locking" of quantum dots are achieved through intelligent rheological control; in the curing and demolding stage, "super-slippery interface and bulk buffering" are achieved through interface energy engineering and internal stress dispersion.

[0061] 1. First Dimension: Intelligent Rheological Control – Achieving “Fixed-Point Anchoring” of Quantum Dots

[0062] Shear thinning and structure locking (amphiphilic structurer): An amphiphilic structurer (such as hydrogenated castor oil) is used at a mass fraction of 0.5%-2%. In a static state, it forms a strong three-dimensional nanofiber network, imparting high viscosity to the colloid and preventing component sedimentation. Under the high shear force (50-100 bar) of imprinting, this network is instantly disrupted, and the viscosity drops sharply (shear thinning), achieving rapid, defect-free cavity filling similar to a liquid.

[0063] Once the pressure stabilizes, the three-dimensional network can be rapidly reconstructed within 1-3 seconds, "freezing" the quantum dots that have been filled into place in their positions. This effectively suppresses redistribution caused by Brownian motion or thermal convection in subsequent processes, thus eliminating non-uniformity from a dynamic perspective.

[0064] Steric hindrance stabilization (quantum dot-specific dispersant): This is achieved through the design of a block copolymer dispersant. Anchoring groups such as phosphonic acid groups at one end of the molecule form a strong bond with the quantum dot surface, while the polyacrylate segments at the other end are compatible with the imprinting adhesive matrix. This structure forms a stable steric hindrance layer around the quantum dots, preventing aggregation of the quantum dots during colloidal preparation, storage, and flow, thus ensuring their initial and ongoing monodispersity.

[0065] 2. Second Dimension: Interface-Volume Coordination Management – ​​Achieving “Complete Deconstruction” of Patterns

[0066] Gradient interfacial energy design (interfacial slip layer): Fluorinated surfactants are introduced into the imprinting adhesive. During thermal or UV curing, due to their extremely low surface energy and incompatibility with the substrate, they spontaneously and selectively migrate to the colloid-template interface, forming a super-slip layer with molecular-level thickness. The surface energy of this interfacial layer is even lower than that of the template's own anti-stick layer. Together with the internal elastic stress-buffering microspheres, it constitutes a comprehensive release protection system.

[0067] Internal stress buffering mechanism (elastic stress buffering microspheres): This is a major innovation in this case. We uniformly mixed 1%-3% of elastic organosilicon microspheres with a particle size of 100-500nm into the colloid. These microspheres act as countless tiny "mechanical dampers" inside the cured colloid. When demolding stress is generated, they effectively absorb, disperse, and dissipate the stress concentrated in vulnerable areas such as pattern edges and sharp corners through their own elastic deformation, preventing the initiation and propagation of microcracks. This, combined with the interface slip layer, achieves comprehensive stress management from the "interface" to the "bulk phase".

[0068] Table 1 Performance Verification

[0069] Test Project Traditional crafts This technical solution Improvement effect Quantum dot distribution uniformity ±15％ ±3％ Increase by 80% Demolding and peeling force 5-8mN / cm <3mN / cm Reduce by 60% Pattern edge tearing defect density <![CDATA[1000defects / cm 2 ]]> <![CDATA[<50defects / cm 2 ]]> Reduced by 95%

[0070] Optionally, the process further includes the following steps:

[0071] Step SA: On the back side of the substrate, a matrix-arranged Wheatstone bridge array is fabricated using a photolithography process;

[0072] Step SB: During the imprinting and holding pressure stage, real-time pressure monitoring is performed, and the imprinting pressure state of the entire board is adjusted. Among them, the pressure distribution data of the entire board is collected through the Wheatstone bridge array on the back, and the distributed piezoelectric actuators on the imprinting head are controlled by the algorithm to achieve dynamic and local fine-tuning of pressure to ensure the pressure uniformity of the entire board.

[0073] Step SC: After step S4, the Wheatstone bridge array on the back side of the substrate is removed by selective wet etching; after etching, it is cleaned and dried to obtain a clean final display device.

[0074] Each of the four resistor arms in the Wheatstone bridge array adopts a serpentine structure and is connected to the data interface at the edge of the substrate via an active matrix addressing method, enabling high-speed, parallel data acquisition of the pressure distribution across the entire board. The Wheatstone bridge can include a transverse force-measuring bridge and a longitudinal force-measuring bridge, used to test stress in both transverse and longitudinal dimensions, respectively. The transverse force-measuring bridge is composed of transversely arranged deformable grids and longitudinally arranged non-deformable grids; the longitudinal force-measuring bridge is composed of longitudinally arranged deformable grids and transversely arranged non-deformable grids; the transverse and longitudinal force-measuring bridges are alternately distributed on the backplane.

[0075] The Wheatstone bridge will now be discussed further.

[0076] 1. Design of a single sensing unit (Wheatstone bridge)

[0077] Structure: A full-bridge circuit is used. All four resistor arms (R1, R2, R3, R4) are composed of serpentine (winding) ITO resistor strips.

[0078] Using a serpentine resistor increases the initial resistance: ITO films are very thin, and their sheet resistance is limited. The serpentine design allows for a larger resistance value within a limited area, improving the voltage output sensitivity of the bridge circuit. Enhanced pressure sensitivity: When the substrate is subjected to vertical pressure, it undergoes minute bending deformation. Due to its longer length, the serpentine resistor exhibits a more significant change in resistance (ΔR) with deformation (strain). The serpentine design makes it more responsive to stresses from different directions, making it more suitable for monitoring uniformly pressed conditions such as embossing.

[0079] Layout: The four resistor arms should be physically as close as possible to form a compact "pixel" to detect localized pressure in a tiny area (e.g., 1mm x 1mm, 5mm x 5mm). A typical arrangement is four resistors arranged in a square around a central point.

[0080] 2. Arrayed arrangement of sensing units

[0081] The array arrangement of sensor units can adopt the concept of "zoned monitoring". For example, the substrate can be divided into a 5mm x 5mm grid, with one sensor unit placed at the center of each grid. This can effectively monitor the pressure trend of the entire board while controlling the system complexity.

[0082] The array of sensing units can be arranged in the following ways:

[0083] Option A: Direct lead-out (suitable for low-resolution arrays)

[0084] Method: The input terminals (Vin+, Vin-) and output terminals (Vout+, Vout-) of each Wheatstone bridge are connected to a giant interface at the edge of the substrate via independent leads. Disadvantage: For an N x N array, the number of leads is approximately 4 x N. 2 When N is very large (e.g., N=100, then 40,000 leads are needed), this is impossible in practice, as the wiring space and interface size cannot accommodate it.

[0085] Option B: Active Matrix Addressing

[0086] Method: Borrow driving technology from TFT-LCD or OLED displays.

[0087] Row scanning and data reading: Connect the rows and columns of the sensor unit array respectively.

[0088] Integrated switch: Next to each sensing unit, a miniature switching element (such as an ITO-based diode or an oxide TFT fabricated at low temperature) is created through an additional photolithography step.

[0089] Working principle: An external drive circuit sequentially applies a "strobe" voltage to each row. When a row is strobe-enabled, the switches of all sensing units in that row are turned on, and the signals of each bridge are read out through their respective data lines. The system scans row by row at high speed, thereby acquiring the pressure data of the entire array in one cycle.

[0090] Advantages: Significantly reduced number of leads: For an N x N array, only about N+M leads are needed (N is the number of rows and M is the number of columns), achieving a leap from "square" to "linear" and making ultra-large-scale sensor arrays possible.

[0091] Perfectly compatible with display technology: This technology is based on existing display panel manufacturing processes, making it easy to integrate and implement.

[0092] Furthermore, it is worth mentioning that the sensor array is used to monitor the stress deformation of the substrate itself, and does not require optical alignment with the pattern and imprint template on the front side.

[0093] 3. Pressure Acquisition

[0094] Calibration: The entire sensor array needs to be calibrated before the system is used. Under known pressure, the output voltage of each sensing unit is recorded, and a "pressure-voltage" lookup table is established to eliminate manufacturing deviations between individual units.

[0095] Data acquisition: During the imprinting and holding pressure stage, the active matrix scanning circuit is activated to read the output voltage of each sensing unit in the entire array at high speed and in a loop.

[0096] Signal processing: The data acquisition system converts the voltage signal into a pressure value in real time using a calibration curve.

[0097] Cloud map generation: All pressure values ​​are mapped to a two-dimensional matrix based on their physical location, generating a visualized real-time pressure distribution cloud map. This cloud map directly shows where the pressure is insufficient (potentially incomplete) and where the pressure is too high (potentially damaging the template or quantum dots).

[0098] Feedback control: The control algorithm analyzes the cloud map, generates compensation instructions, and drives the piezoelectric ceramic actuator at the corresponding position on the imprint head to make fine adjustments by "pushing" or "pulling", so that the entire cloud map tends to be uniformly green (target pressure value).

[0099] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A nanoimprint process for improving the uniformity of distribution of nanoscale quantum dot light emitting units, characterized in that, The process comprises the following steps: S1: substrate interface treatment, forming an enhanced adhesion interface layer on the substrate surface; S2: preparing quantum dot composite imprinting glue, dispersing quantum dots, amphiphilic structuring agent, fluorine-containing surfactant and elastic stress buffer microspheres in the imprinting glue matrix to form quantum dot composite imprinting glue with shear thinning characteristics; S3: gluing and imprinting, coating the quantum dot composite imprinting glue on the treated substrate, and using a nano-imprint template to perform imprinting at a set temperature and pressure; S4: curing and demolding, curing the quantum dot composite imprinting glue in the imprinted state, and then separating the nano-imprint template from the cured glue; In the imprinting process of step S3, the amphiphilic structuring agent reduces the viscosity of the glue under the action of shear force to achieve rapid filling, and its three-dimensional network structure is quickly rebuilt to lock the position of the quantum dots after the pressure is stable; at the same time, in the curing process of step S4, the fluorine-containing surfactant spontaneously migrates to the glue-template interface to form a slip layer, and the elastic stress buffer microspheres disperse the stress in the cured glue, together realizing non-damaging demolding with a peeling force less than 3 mN / cm.

2. The nanoimprint process according to claim 1, wherein The amphiphilic structuring agent is hydrogenated castor oil or polyamide wax, and its mass percentage in the quantum dot composite imprinting glue is 0.5% to 2%.

3. The nanoimprint process of claim 1, wherein, The elastic stress buffer microspheres are silicone microspheres with an average particle size of 100 nm to 500 nm, and their mass percentage in the quantum dot composite imprinting glue is 1% to 3%.

4. The nanoimprint process of claim 1, wherein, The fluorine-containing surfactant and the anti-sticking layer on the surface of the nano-imprint template together constitute a gradiently descending interface energy system, and the surface energy of the interface slip layer is lower than that of the anti-sticking layer.

5. The nanoimprint process of claim 1, wherein, The interface treatment of the substrate is to spin a layer of silane coupling agent, which forms chemical bonding with the substrate surface and chemical crosslinking with the cured imprinting glue.

6. The nanoimprint process of claim 1, wherein, The quantum dot composite imprinting glue further comprises a quantum dot-specific dispersant, which is a block copolymer with an anchoring group anchored on the surface of the quantum dots at one end and a polymer segment compatible with the imprinting glue matrix at the other end.

7. The nanoimprint process of claim 1, wherein, The quantum dot pattern prepared by the process has a quantum dot distribution uniformity variation coefficient less than ±3% and a pattern edge tearing defect density less than 50 defects / cm 2 .

8. The nanoimprint process of claim 1, wherein, The process further comprises the following steps: Step SA: on the back of the substrate, a matrix-arranged Wheatstone bridge array is prepared through a photolithography process; Step SB: during the imprinting pressure maintaining stage, real-time pressure monitoring is performed, and the imprinting pressure state of the whole plate is adjusted and controlled; wherein, the whole plate pressure distribution data are collected through the Wheatstone bridge array on the back, and the distributed piezoelectric actuators on the imprinting head are controlled through an algorithm to realize dynamic and local fine adjustment of the pressure, so as to ensure the uniformity of the pressure of the whole plate; Step SC: after step S4, the Wheatstone bridge array on the back of the substrate is removed through selective wet etching; after etching, cleaning and drying, a final display device with a clean back is obtained.

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