Display panel and preparation method thereof

Abstract

Embodiments of the present application provide a display panel and a preparation method thereof, wherein the display panel comprises: a substrate layer; a driving circuit layer arranged on one side of the substrate layer; excitation light sources arranged in an array on a side of the driving circuit layer away from the substrate layer; a flat layer arranged on a side of the driving circuit layer away from the substrate layer, and the excitation light sources are embedded in the flat layer; a pixel layer located on a side of the flat layer away from the substrate layer, the pixel layer comprises a plurality of sub-pixels arranged in an array, and each sub-pixel is arranged correspondingly to each excitation light source; and a protective layer located on a side of the pixel layer away from the substrate layer; wherein the preparation material of the sub-pixels comprises up-conversion nanocrystals, and the excitation light sources are near-infrared micro-LEDs. The display panel and the preparation method thereof provided by the embodiments of the present application use up-conversion nanocrystals as light-emitting pixels, generate visible light by exciting near-infrared light, completely abandon traditional structures such as polarizing plates, color filters, liquid crystal layers, and the like, and obtain a display panel with a highly simplified structure and excellent performance.

Description

Technical Field

[0001] This application belongs to the field of display technology, and in particular relates to a display panel and its manufacturing method. Background Technology

[0002] LCD (Liquid Crystal Display) is a technology that uses liquid crystals to control light to display images. Liquid crystals themselves do not emit light and require a backlight. When a voltage is applied to the liquid crystal, its molecules change their alignment, thus controlling whether light can pass through. In the field of display technology, LCD is the mainstream flat-panel display solution. Its traditional architecture includes key components such as polarizers, color filters, and liquid crystal layers. This technology achieves image display by modulating polarized light through liquid crystal molecules. Its physical mechanism leads to multiple light energy losses: the unidirectional transmission characteristic of the polarizer causes energy loss from the backlight; the absorption-based color separation of the color filter further reduces light efficiency; and the electronically controlled phase modulation of the liquid crystal layer results in low overall system light utilization efficiency. This multi-layered composite structure not only significantly increases the thickness and weight of the display module but also causes viewing angle distortion due to multiple refractions of light, resulting in contrast limited by the backlight brightness level and making it difficult to adapt to the needs of flexible displays.

[0003] Existing research indicates that, to overcome the aforementioned technological bottlenecks, the industry has explored polarization alternatives based on microstructured optical films and novel display architectures such as liquid crystal photonic crystals. However, these technological approaches are still limited by the photoelectric response characteristics of liquid crystal materials, exhibiting the following common drawbacks: 1) Microstructured optical films require precise nanoscale processing, resulting in low yield rates; 2) Photonic crystal structures lead to a decrease in the effective display area ratio, limiting resolution; 3) Wide viewing angle compensation technology relies on complex multilayer film stacking, increasing system costs. Existing polarizer-free technologies have not yet overcome the fundamental physical mechanisms constraining liquid crystal modulation of light, and significant technical obstacles remain in terms of mass production feasibility, cost control, and performance indicators. Summary of the Invention

[0004] In view of this, embodiments of this application provide a display panel and a method for manufacturing the same, in order to solve the technical problem of the existing display industry's long-term reliance on polarizers / liquid crystal layers, which leads to complex structures.

[0005] In a first aspect, embodiments of this application provide a display panel, including: Substrate layer; A driving circuit layer is disposed on one side of the substrate layer; An excitation light source is arrayed on the side of the driving circuit layer away from the substrate layer; A planarization layer is disposed on the side of the driving circuit layer away from the substrate layer, and the excitation light source is embedded in the planarization layer; A pixel layer is located on the side of the planarization layer away from the substrate layer. The pixel layer includes a plurality of sub-pixels arranged in an array, and each sub-pixel is correspondingly arranged with a single excitation light source. A protective layer is located on the side of the pixel layer away from the substrate layer; The sub-pixel is made of upconversion nanocrystals, and the excitation light source is a near-infrared micro-LED.

[0006] In some embodiments, the protective layer is a single-layer or multi-layer encapsulation structure, and the protective layer includes at least one of a silicon dioxide layer, a flexible substrate layer, an aluminum oxide layer, and an optically transparent adhesive layer.

[0007] In some embodiments, an adhesive layer is further provided between the planarization layer and the pixel layer. Preferably, the adhesive layer is an optically transparent adhesive layer.

[0008] In some embodiments, a BM frame is further provided between adjacent sub-pixels.

[0009] In some embodiments, the driving circuit layer includes driving electrodes and pads required for the excitation light source, the excitation light source is disposed on the pads, and the driving electrodes are used to connect the excitation light source to an external circuit.

[0010] In some embodiments, the sub-pixel includes at least one of a red sub-pixel, a blue sub-pixel, and a green sub-pixel.

[0011] In some embodiments, the protective layer is made of the same material as the substrate layer, and both the protective layer and the substrate layer are one of the following: glass substrate, polyimide substrate, polyethylene terephthalate substrate, polyethylene naphthalate substrate, transparent polyimide substrate, cyclic olefin polymer substrate, and polycarbonate substrate.

[0012] Secondly, embodiments of this application provide a method for manufacturing a display panel, comprising the following steps: Provide substrate layer; A driving circuit layer is deposited on one side of the substrate layer; An excitation light source is arrayed on the side of the driving circuit layer away from the substrate layer; A planarization layer is formed on the driving circuit layer away from the substrate layer, and the excitation light source is embedded in the planarization layer; A pixel layer is formed on the side of the excitation light source away from the substrate layer. The pixel layer includes a plurality of sub-pixels arranged in an array, wherein each sub-pixel is disposed corresponding to a single excitation light source. A protective layer is formed on the side of the pixel layer away from the excitation light source.

[0013] In some embodiments, an adhesive layer is provided between the planarization layer and the pixel layer, wherein the preparation of the adhesive layer includes: A transparent optical adhesive with a preset refractive index is filled between the pixel layer and the planarization layer; A roll forming process is used to connect the planarization layer and the pixel layer to the adhesive layer under preset conditions.

[0014] In some embodiments, the excitation light source is a near-infrared micro-light-emitting diode, and the excitation light source is arrayed on the side of the driving circuit layer away from the substrate layer, including: Using laser peeling and flexible stamp transfer technology, a large number of near-infrared micro light-emitting diodes are transferred to pre-designed pads on the first driving circuit layer; Electrical and mechanical connections are made using anisotropic conductive adhesive or micro solder bumps; Each near-infrared micro-light-emitting diode is directly connected to one of the sub-pixels and is independently driven by the corresponding driving electrode.

[0015] In some embodiments, a pixel layer is formed on the side of the excitation light source away from the substrate layer. The pixel layer includes a plurality of sub-pixels arranged in an array, wherein each sub-pixel corresponds to a single excitation light source, including: Preparation of core-shell structured upconversion nanocrystalline materials; The upconversion nanocrystalline material is mixed with a solvent and a dispersant, and after ball milling and centrifugation, a viscosity-stable printing ink is formed, wherein the printing ink includes at least one of red, blue, and green. A sub-pixel array is printed on the side of the excitation light source away from the substrate layer; The pixel layer is obtained after heat treatment and curing.

[0016] The display panel and its fabrication method provided in this application propose a novel self-emissive display panel based on upconversion nanocrystals and near-infrared micro-LEDs, completely eliminating the liquid crystal layer, color filter, and polarizer found in traditional LCDs. The pixel layer achieves efficient, narrow-band, and high-color-purity visible light emission under near-infrared light excitation. This architecture requires no electrical injection, relying solely on light-to-light conversion, and possesses ultra-high contrast, wide color gamut, low power consumption, and excellent environmental stability. The process employs additive manufacturing, resulting in high material utilization, compatibility with flexible substrates and low-temperature processes, and combines the self-emissive advantages of OLEDs with the long-life characteristics of inorganic materials, providing a new technological path for high-reliability, high-definition displays. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, 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 of the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the display panel provided in the embodiments of this application. Figure 1 ; Figure 2 This is a schematic diagram of the light source of the display panel provided in the embodiments of this application. Figure 1 ; Figure 3 This is a schematic diagram of the structure of the display panel provided in the embodiments of this application. Figure 2 ; Figure 4 This is a schematic diagram of the light source of the display panel provided in the embodiments of this application. Figure 2 ; Figure 5 This is a schematic flowchart of the method for manufacturing a display panel provided in an embodiment of this application.

[0019] The attached icon numbers are as follows: 10. Substrate layer; 20. Driving circuit layer; 30. Excitation light source; 40. Planarization layer; 50. Pixel layer; 500. Subpixel; 501. BM frame; 60. Protective layer; 70. Adhesive layer. Detailed Implementation

[0020] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that the embodiments of this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the embodiments of this application with unnecessary detail.

[0021] It should also be understood that the term "and / or" as used in the specification of embodiments of this application and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0022] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0023] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application 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 the embodiments of this application.

[0024] Furthermore, in the description of the embodiments and the appended claims of this application, the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0025] In the description of embodiments in this application, references to "some embodiments" or "some embodiments" mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in some embodiments," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiments, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. "A plurality" refers to two or more.

[0026] The first aspect of this application provides a display panel, such as... Figure 1 and Figure 2 As shown, the display panel includes a substrate layer 10, a driving circuit layer 20, an excitation light source 30, a planarization layer 40, a pixel layer 50, and a protective layer 60. The driving circuit layer 20 is disposed on one side of the substrate layer 10; The excitation light source 30 is a near-infrared micro LED (μLED, micro light-emitting diode), and the array of excitation light sources 30 is disposed on the side of the driving circuit layer 20 away from the substrate layer 10; The planarization layer 40 is disposed on the side of the driving circuit layer 20 away from the substrate layer 10, and the excitation light source 30 is embedded in the planarization layer 40. The pixel layer 50 is located on the side of the planarization layer 40 away from the substrate layer 10. The pixel layer 50 includes a plurality of sub-pixels 500 arranged in an array, and each sub-pixel 500 is correspondingly arranged with a single excitation light source 30. The protective layer 60 is located on the side of the pixel layer 50 away from the substrate layer 10; The material used to fabricate sub-pixels 500 includes upconversion nanocrystals.

[0027] The display panel provided in this application innovatively uses upconversion nanocrystalline materials as direct-emitting pixels, generating visible light through near-infrared light excitation. This completely eliminates traditional structures such as polarizers, color filters, and liquid crystal layers, and thoroughly abandons the physical principle of liquid crystal modulation of polarized light, achieving a technological breakthrough at the fundamental level. The display panel of this application achieves efficient, narrow-band, and high-color-purity visible light emission through the combination of upconversion nanocrystalline materials and near-infrared micro-LEDs (NIR μLEDs). This architecture requires no electrical injection, relying solely on light-to-light conversion, and possesses ultra-high contrast, wide color gamut, low power consumption, and excellent environmental stability.

[0028] It should be noted that the basic principle of upconversion nanocrystal luminescence is as follows: Upconversion nanocrystals (UCNPs) are a type of photoluminescent material whose working mechanism is based on a multiphoton absorption process (usually two or more low-energy photons are absorbed successively, eventually emitting a high-energy photon). A typical process is as follows: the excitation light source 30 is near-infrared light (e.g., 980nm or 808nm). In this application embodiment, a near-infrared micro-LED is used, emitting visible light (e.g., red ~650nm, green ~540nm, blue ~475nm). Through the entire process, rare earth ions (e.g., Yb) are emitted. 3+ / Er 3+ Yb 3+ / Tm 3+ The energy level transition is achieved through a purely optical process, without charge injection or current involvement.

[0029] In some embodiments, the substrate layer 10 serves as the mechanical support foundation for the entire display panel, bearing all subsequent functional layers. Specifically, the substrate layer 10 can be a rigid or flexible substrate. Further, the rigid substrate can be one of alkali-free glass, quartz glass, or silicon wafer. The flexible substrate includes one of polyimide substrate, polyethylene terephthalate substrate, polyethylene naphthalate substrate, transparent polyimide substrate, cyclic olefin polymer substrate, or polycarbonate substrate. When a flexible substrate is used, the protective layer 60 uses the same material as the substrate layer 10, thus enabling a flexible display screen.

[0030] In some embodiments, the protective layer 60 is a single-layer or multi-layer encapsulation structure, and the protective layer 60 includes at least one of a silicon dioxide layer, a flexible substrate layer 10, an aluminum oxide layer, and an optically transparent adhesive layer. This protects the pixel layer 50 (upconversion nanocrystalline material layer), preventing water and oxygen from entering the panel and thus protecting the device. Preferably, the protective layer 60 is a silicon dioxide layer.

[0031] In some embodiments, such as Figure 1 and Figure 2As shown, an adhesive layer 70 is also provided between the planarization layer 40 and the pixel layer 50. Preferably, the adhesive layer 70 is an optically transparent adhesive layer (OCA adhesive). Providing an optically transparent adhesive layer 70 between the planarization layer 40 and the pixel layer 50 is not merely a simple bonding requirement, but a key technical means to achieve efficient optical coupling, precise pixel alignment, flexibility, reliability, and environmental stability.

[0032] In applications, the planarization layer 40, typically made of silicone or acrylic resin, has a refractive index difference with the UCNP pixel layer 50 (containing organic ligands / solvent residues). Direct contact can lead to air gaps or interface scattering. The refractive index of the OCA adhesive can be designed to be around n=1.5 (1.48~1.52) to achieve refractive index matching, effectively reducing Fresnel reflection loss of near-infrared excitation light at the interface. This improves the transmission efficiency of NIR light to UCNPs and enhances the upconversion luminescence intensity. The UCNP pixel layer 50 is usually prepared by inkjet printing or transfer. If it is only attached to the planarization layer 40 by van der Waals forces, it is prone to displacement or peeling during subsequent processes (such as bonding and bending).

[0033] OCA provides strong adhesion, firmly binding the pixel layer 50 to the planarization layer 40, maintaining a one-to-one correspondence between a UCNP sub-pixel 500 and a NIR μLED. This avoids color shift, crosstalk, or uneven brightness caused by pixel misalignment, ensuring display quality. Furthermore, in flexible display applications, repeated bending can generate thermal expansion coefficient mismatch stress between different material layers. As an elastic interlayer, OCA can absorb local strain, preventing UCNP pixel cracking or μLED solder joint fatigue. This significantly improves the device's lifespan under dynamic bending.

[0034] It is worth mentioning that an adhesive layer 70 is provided between the pixel layer 50 and the planarization layer 40. This is because the pixel layer 50 and the excitation light source 30 are fabricated separately and then bonded together by the adhesive layer 70. In other embodiments, the pixel layer 50 can be formed directly on the excitation light source 30 (planarization layer 40), thus eliminating the need for the adhesive layer 70, further reducing the thickness of the display panel, which is beneficial for thinner and lighter applications.

[0035] In some embodiments, subpixel 500 includes at least one of red, blue, and green subpixels. In some embodiments, pixel layer 50 contains only green subpixels, suitable for high-brightness monochrome display scenarios; in other embodiments, it includes red and blue subpixels for basic color indication; in a preferred embodiment, it includes red, green, and blue subpixels to achieve full-color display. Not all applications require full-color display. Monochrome displays, such as electronic price tags, industrial instruments, and medical monitoring screens, only require green (most sensitive to the human eye) or red (high transmittance). Dual-color displays, such as traffic signal simulations and status indicators, may only require red + green or blue + white. Special color gamut applications, such as bio-imaging and anti-counterfeiting labels, may use non-standard colors (such as yellow and orange) UCNPs, but are still based on the Yb sensitization system.

[0036] In some embodiments, such as Figure 1 and Figure 2 As shown, a BM frame 501 (black matrix) is also provided between adjacent sub-pixels 500. This helps to block the lateral diffusion of excitation light. The near-infrared light emitted by NIR μLEDs has a certain divergence angle. Without BM isolation, some NIR light will obliquely illuminate the UCNPs of neighboring sub-pixels 500. Areas that should display red are mistakenly excited by green / blue UCNPs, resulting in color aliasing and decreased color purity. The BM frame 501 acts as a light barrier, absorbing or reflecting stray NIR light to ensure accurate excitation of one pixel per LED. When displaying a black screen, all NIR μLEDs are turned off, and ideally there should be no light output. However, ambient light may enter from the front and undergo multiple reflections at the pixel layer 50 / planar layer 40 interface, forming a gray background. The BM frame 501 acts as a light-absorbing network, capturing these stray reflected lights and making the black state purer.

[0037] In applications, BM patterns can integrate alignment marks for real-time positioning during UCNP inkjet printing and high-precision alignment when bonding with NIR μLED backplanes. The surface energy difference between BM materials (such as black photoresist) and UCNP inks guides ink droplets to be confined within the opening area, preventing spreading. On flexible substrates, the mesh structure formed by BMs can suppress localized stress concentrations, reducing the risk of UCNP layer cracking during bending.

[0038] In some embodiments, the driving circuit layer 20 includes driving electrodes and pads (not shown) required for the excitation light source 30. The excitation light source 30 is disposed on the pads, and the driving electrodes are used to connect the excitation light source 30 to external circuitry. The pads serve as the physical mounting platform and electrical interface for the NIR μLED chips. They provide a precise placement reference during mass transfer of μLEDs; low-resistance, reliable electrical connections are achieved through ACF (anisotropic conductive adhesive) or microbumps. In applications, they are typically made of highly conductive metals (such as Au, Cu, Al, or ITO); the surface is exposed through a passivation layer, and the size is slightly larger than the μLED electrodes, with the position strictly corresponding to the sub-pixels 500 of the UCNPs above. The pads are electrically connected to external driving ICs (such as source / gate driving chips on COF). Furthermore, they also include scan lines (Gate Lines) and data lines (Source Lines); TFT switches (simplified type, used only for current switching) can be integrated. Pixel-level independent addressing is achieved: each NIR μLED can be individually turned on / off; high refresh rate image data writing is supported, reducing line resistance, power consumption, and heat generation. In practical applications, the pads are made of transparent conductive material or metal material with a surface roughness Ra < 5nm to adapt to the mass transfer process of μLED chips. The driving electrode and the pads are formed in the same process and are located on the same plane. The pads are formed by sputtering ITO and photolithography etching, and the driving electrode is a Mo / Al / Mo sandwich structure. The two are aligned through the same mask to ensure a positional deviation of < ±1μm.

[0039] In applications, the driving electrodes and pads are integrated into the driving circuit layer 20. This avoids additional wiring layers and simplifies the stacking structure. If the pads and driving electrodes belong to different layers, they need to be connected through vias, increasing process complexity and failure risk. Integrating them into the same layer, the driving circuit layer 20 (usually the first metal layer), allows for: defining the electrode and pad pattern in a single photolithography step; and direct surface mounting of μLEDs without vertical interconnects.

[0040] Laser stripping and flexible stamp transfer require a flat pad surface with no steps covering it; if the driving electrode is located on the same plane below the pad, global coplanarity can be achieved through a planarization layer to meet the transfer accuracy requirements.

[0041] like Figures 1 to 5 As shown in the embodiments of this application, a method for manufacturing a display panel is also provided, comprising the following steps: S10, Provide substrate layer 10; S20. Deposit a driving circuit layer 20 on one side of the substrate layer 10; S30, An excitation light source 30 is arranged in an array on the side of the driving circuit layer 20 away from the substrate layer 10; S40. A planarization layer 40 is formed in the driving circuit layer 20 away from the substrate layer 10, and the excitation light source 30 is embedded in the planarization layer 40. S50, A pixel layer 50 is formed on the side of the excitation light source 30 away from the substrate layer 10. The pixel layer 50 includes a plurality of sub-pixels 500 arranged in an array, wherein each sub-pixel 500 is arranged corresponding to a single excitation light source 30. S60, a protective layer 60 is formed on the side of the pixel layer 50 away from the excitation light source 30.

[0042] The display panel manufacturing method provided in this application adopts additive manufacturing process, which has high material utilization rate, is compatible with flexible substrate and low temperature process, and combines the self-emissive advantages of OLED and the long lifespan characteristics of inorganic materials, providing a new technical path for high reliability and high image quality display.

[0043] In step S10, a substrate layer 10 is provided. The substrate layer 10 can be an alkali-free glass substrate or other flexible substrates. The substrate layer 10 is ultrasonically cleaned and dried with nitrogen gas for subsequent use.

[0044] In step S20, a driving circuit layer 20 is deposited on one side of the substrate layer 10. An ITO (indium tin oxide) transparent conductive layer is deposited on the substrate layer 10 to form the driving circuit layer 20. The driving circuit layer 20 includes drive electrodes for scan lines, data lines, and the excitation light source 30. Additionally, pads for mounting the excitation light source 30 are provided on the side of the driving circuit layer 20 away from the substrate layer 10. This is a key difference from conventional LCD TFTs: the driving circuit layer 20 of this invention does not need to generate a uniform electric field; it is only used as a high-current switch. Therefore, a simplified design is adopted: the driving circuit layer 20 is deposited on the substrate by depositing a gate metal layer.

[0045] In step S30, an excitation light source 30 is arrayed on the side of the driving circuit layer 20 away from the substrate layer 10. The excitation light source 30 is a near-infrared micro-light-emitting diode (NIR μLED). In application, laser lift-off and flexible stamp transfer technology are used to massively transfer μLED chips onto pre-set pads on the driving circuit layer 20, and electrical and mechanical connections are made through anisotropic conductive adhesive or micro solder bumps. Each μLED is directly connected to a pixel unit of the driving electrode and is driven independently by it. In other embodiments, anisotropic conductive adhesive can also be used for lamination at a lamination temperature of 180°C, a pressure of 5 MPa, and a time of 10 s to achieve electrical connection between the TFT circuit and the NIR μLED.

[0046] In step S40, a planarization layer 40 is formed on the driving circuit layer 20 away from the substrate layer 10, and the excitation light source 30 is embedded in the planarization layer 40. A layer of transparent silicon-based encapsulant is coated on the transferred μLED array for protection, and the planarization layer 40 is obtained by chemical mechanical polishing, providing a flat surface for subsequent bonding.

[0047] In step S50, a pixel layer 50 is formed on the side of the excitation light source 30 away from the substrate layer 10. The pixel layer 50 includes a plurality of sub-pixels 500 arranged in an array, wherein each sub-pixel 500 is correspondingly arranged with respect to a single excitation light source 30. Specifically, this includes: S51. Prepare core-shell structured upconversion nanocrystalline materials; wherein, core-shell structured NaYF4:Yb,Er (green light: emission peak 540nm; red light: emission peak 650nm) and NaYF4:Yb,Tm (blue light: emission peak 450nm) are used as luminescent materials.

[0048] S52. Upconversion nanocrystalline materials are mixed with solvents and dispersants, and after ball milling and centrifugation, a viscosity-stable printing ink is formed. The printing ink includes at least one of red, blue, and green. The dispersibility is improved through surface ligand engineering (using oleic acid-PEG5000 modification) to prepare the printing ink, thereby achieving R / G / B (red, green, blue) three-color display without the need for color filters. Specifically, UCNPs are mixed with solvents (such as dodecane, decane) and dispersants (such as HSD-Y104, modified hydrogenated styrene-butadiene block copolymer), and after ball milling and centrifugation, a viscosity-stable printing ink is formed.

[0049] S53. Print a sub-pixel array of 500 on the side of the excitation light source 30 away from the substrate layer 10; completely replacing the photolithography process in the color filter substrate, using a piezoelectric on-demand inkjet printer, directly prints the R / G / B three-color UCNPs pixel array on a substrate treated with UV-O zone to improve wettability, according to a digital pattern file. This process eliminates the need for masks, exposure, and development, greatly simplifying the fabrication process.

[0050] S54. After heat treatment and curing, pixel layer 50 is obtained. Specifically, heat treatment is performed at 90°C for 20 minutes to evaporate the solvent and enhance the adhesion between UCNPs pixels and the substrate, thus forming pixel layer 50.

[0051] In application, the pixel layer 50 fabrication method, through four innovations—core-shell UCNPs material design, dedicated ink engineering, digital inkjet printing, and low-temperature curing—successfully achieved the replacement of absorptive color filters with luminescent pixels and subtractive lithography with additive manufacturing; thus realizing the fabrication of display panels with high color gamut, high efficiency, and high reliability. This is not only an optimization of the manufacturing process but also a paradigm shift in display technology, providing a solid technical path for building next-generation high-efficiency, flexible, and environmentally friendly self-emissive display panels.

[0052] In some embodiments, a black matrix is ​​obtained by repeating step S53 to pattern print between sub-pixels 500.

[0053] In step S60, a protective layer 60 is formed on the side of the pixel layer 50 away from the excitation light source 30. This is applicable to cases where only one glass substrate is used, i.e., after the NIR μLED backplane and driving circuit are prepared, red UCNPs ink, green UCNPs ink, and blue UCNPs ink are sequentially sprayed onto the NIR μLED in R / G / B pixel pattern, and then cured after printing. Finally, a silicon dioxide protective layer 60 is spin-coated onto the surface of the pixel layer 50 to prevent UCNPs from oxidation and mechanical damage.

[0054] In other embodiments, such as Figure 3 and Figure 4 As shown, a double-layer substrate can also be used, in which case the pixel layer 50 and the excitation light source 30 can be fabricated separately. Specifically: A substrate (protective layer 60) is provided, and at least one pixel among R / G / B is patterned on the glass substrate using the printing ink obtained by the above method, resulting in a glass substrate with pixel layer 50. Additionally, steps S10 to S40 are repeated on another substrate to obtain a glass substrate with excitation light source 30, which is then aligned and bonded. The alignment step includes: placing the substrate with the UCNPs pixel layer 50 and the substrate with the NIR μLED array driving circuit layer 20 on a precision alignment platform. Alignment marks are identified using a high-precision CCD camera, precisely aligning each UCNPs pixel with its corresponding NIR μLED chip. The bonding step includes: filling the space between the two substrates with a transparent optical adhesive with a refractive index matching (n≈1.5). A roll forming process is used to fully bond and cure the substrate under slight pressure and heat. This process involves only physical bonding and avoids complex issues such as liquid crystal injection, sealing, and cell thickness control. Finally, a novel display panel based on upconversion nanocrystals was obtained.

[0055] In some embodiments, when a single substrate is used, an adhesive layer 70 may be provided between the planarization layer 40 and the pixel layer 50, wherein the preparation of the adhesive layer 70 includes: A transparent optical adhesive with a preset refractive index is filled between the pixel layer 50 and the planarization layer 40; Using a roll forming process, the flattening layer 40 and the pixel layer 50 are connected to the adhesive layer 70 under preset conditions.

[0056] In some embodiments, the method further includes a step of bonding peripheral circuitry. By bonding a COF (Chip on Film) driver chip to support pixel-level current regulation, connecting a flexible circuit board, and realizing external signal (driving control of NIR μLEDs), a complete novel display panel based on upconversion nanocrystals without polarizers or color filters is finally formed.

[0057] The display panel and its manufacturing method provided in this application have the following advantages: 1. The cost is significantly lower than that of traditional LCD display devices. This is primarily due to the elimination of the need for vapor deposition machines and polarizer bonding machines; the core equipment consists of inkjet printers and low-temperature bonding machines. In terms of materials, UCNPs materials are only one-third the price of OLED organic materials, with a material utilization rate of 95% (compared to <30% for traditional OLED vapor deposition). Furthermore, it eliminates the need for polarizers, color filters, and liquid crystal cells. In addition, the process is simplified and more environmentally friendly.

[0058] 2. Extremely simplified structure. Compared with traditional LCDs, the structural layers such as color filter substrate, polarizer, and liquid crystal layer are reduced, and the module thickness is reduced to 1.2mm (traditional LCD thickness is 2.5mm).

[0059] 3. Excellent display performance. The self-emissive characteristic brings high contrast (self-emissive, almost no light in black) and wide color gamut, with no polarizer loss, and the light extraction efficiency is effectively improved; moreover, it has the advantage of low power consumption, with the power consumption of the NIR μLED excitation source being much lower than that of traditional LCD backlight.

[0060] 4. Enhanced compatibility. Suitable for all application scenarios, including flexible and large-size displays.

[0061] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0062] The above-described embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them. Although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of the embodiments of this application.

Claims

1. A display panel, characterized in that, include: Substrate layer; A driving circuit layer is disposed on one side of the substrate layer; An excitation light source is arrayed on the side of the driving circuit layer away from the substrate layer; A planarization layer is disposed on the side of the driving circuit layer away from the substrate layer, and the excitation light source is embedded in the planarization layer; A pixel layer is located on the side of the planarization layer away from the substrate layer. The pixel layer includes a plurality of sub-pixels arranged in an array, and each sub-pixel is correspondingly arranged with a single excitation light source. A protective layer is located on the side of the pixel layer away from the substrate layer; The sub-pixel is made of upconversion nanocrystals, and the excitation light source is a near-infrared micro-LED.

2. The display panel as described in claim 1, characterized in that, The protective layer is a single-layer or multi-layer encapsulation structure, and the protective layer includes at least one of a silicon dioxide layer, a PET layer, an aluminum oxide layer, and an OCA layer.

3. The display panel as described in claim 1, characterized in that, An adhesive layer is further provided between the planarization layer and the pixel layer; and / or, A BM frame is also provided between adjacent sub-pixels.

4. The display panel as described in claim 1, characterized in that, The driving circuit layer includes driving electrodes and pads required for the excitation light source. The excitation light source is disposed on the pads, and the driving electrodes are used to connect the excitation light source to an external circuit.

5. The display panel as described in claim 1, characterized in that, The sub-pixel includes at least one of red sub-pixels, blue sub-pixels, and green sub-pixels.

6. The display panel as described in claim 1, characterized in that, The protective layer is made of the same material as the substrate layer, and both the protective layer and the substrate layer are one of the following: glass substrate, polyimide substrate, polyethylene terephthalate substrate, polyethylene naphthalate substrate, transparent polyimide substrate, cyclic olefin polymer substrate, and polycarbonate substrate.

7. A method for preparing a display panel according to any one of claims 1 to 6, characterized in that, Includes the following steps: Provide substrate layer; A driving circuit layer is deposited on one side of the substrate layer; An excitation light source is arrayed on the side of the driving circuit layer away from the substrate layer; A planarization layer is formed on the driving circuit layer away from the substrate layer, and the excitation light source is embedded in the planarization layer; A pixel layer is formed on the side of the excitation light source away from the substrate layer. The pixel layer includes a plurality of sub-pixels arranged in an array, wherein each sub-pixel is disposed corresponding to a single excitation light source. A protective layer is formed on the side of the pixel layer away from the excitation light source.

8. The preparation method according to claim 7, characterized in that, An adhesive layer is provided between the planarization layer and the pixel layer, wherein the preparation of the adhesive layer includes: A transparent optical adhesive with a preset refractive index is filled between the pixel layer and the planarization layer; A roll forming process is used to connect the planarization layer and the pixel layer to the adhesive layer under preset conditions.

9. The preparation method according to claim 7, characterized in that, The excitation source is a near-infrared micro-light-emitting diode, and the excitation source is arrayed on the side of the driving circuit layer away from the substrate layer, including: Using laser peeling and flexible stamp transfer technology, a large number of near-infrared micro light-emitting diodes are transferred to pre-designed pads on the first driving circuit layer; Electrical and mechanical connections are made using anisotropic conductive adhesive or micro solder bumps; Each near-infrared micro-light-emitting diode is directly connected to one of the sub-pixels and is independently driven by the corresponding driving electrode.

10. The preparation method according to claim 7, characterized in that, A pixel layer is formed on the side of the excitation light source away from the substrate layer. The pixel layer includes a plurality of sub-pixels arranged in an array, wherein each sub-pixel corresponds to a single excitation light source, including: Preparation of core-shell structured upconversion nanocrystalline materials; The upconversion nanocrystalline material is mixed with a solvent and a dispersant, and after ball milling and centrifugation, a viscosity-stable printing ink is formed, wherein the printing ink includes at least one of red, blue, and green. A sub-pixel array is printed on the side of the excitation light source away from the substrate layer; The pixel layer is obtained after heat treatment and curing.

Images