A spontaneous light double circular polarization quantum dot display panel based on a semi-injection structure and a preparation method thereof

Abstract

This invention provides a self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure and its fabrication method, belonging to the field of display technology. The display panel, from bottom to top, comprises a substrate, a transparent bridge, a cholesteric liquid crystal polymer layer, a dielectric layer, a hole injection layer, a hole transport layer, an emissive layer, an electron transport layer, an electron injection layer, and electrodes. This invention enables the separation of dual-circularly polarized light output and 3D display channels, simultaneously providing left-handed and right-handed circularly polarized dual channels on the same panel. This invention achieves controllable output and pixel-level dynamic display of the left and right circularly polarized channels by integrating the cholesteric liquid crystal polymer layer and dielectric layer within the panel and employing coplanar electrodes in conjunction with high-frequency AC drive. This invention also utilizes a quantum dot emissive layer, which can meet the requirements of full-color display.

Description

Technical Field

[0001] This invention belongs to the field of display technology, and particularly relates to a self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure and its preparation method. Background Technology

[0002] With the continuous development of extended reality (XR), human-computer interaction, remote control, and immersive visualization technologies, display devices are evolving from traditional two-dimensional (2D) displays to spatial three-dimensional (3D) displays capable of carrying depth information. Existing research shows that circularly polarized light-based displays can utilize the difference in photon spin angular momentum to allow the observer's left and right eyes to receive different information, thereby creating a stereoscopic visual effect, and have potential advantages such as less viewing angle limitation and reduced dizziness.

[0003] Currently, the technical routes for realizing circularly polarized displays can be broadly divided into two categories: (1) External optical scheme: using polarizers, quarter-wave plates, phase delayers or complex micro-nano optical structures to generate / convert circular polarization outside the panel. However, this method has problems such as increased system thickness, loss of light efficiency, complex assembly and increased cost, and alignment and consistency are difficult under high-resolution arrays. (2) Material / device endogenous scheme: using chiral light-emitting materials or integrated structures of light-emitting layer and circular polarization conversion layer that can generate circularly polarized light emission (CPL) in order to make it easier to process and integrate with modern display electronics. Although this technology is considered to have greater integration potential, the literature clearly points out that current chiral light emission / circularly polarized displays still face problems such as insufficient electroluminescence asymmetry when powered on and difficulty in achieving pixel-level real-time dynamic control based on input digital signals. As a result, many schemes are still in the stage of static stereo imaging or prototype, and have not yet formed programmable, arrayable, adjustable CPL display panels.

[0004] On the other hand, cholesteric liquid crystal (CLC) systems, due to their inherent helical structure, can provide selective circular polarization response. Their combination with quantum dots (QDs) and other light-emitting units is considered an important direction for expanding optical states and increasing information capacity. Related research has proposed embedding quantum dots into cholesteric liquid crystal networks (CLCNs), which can simultaneously obtain wide-gamut fluorescent (PL) colors and Bragg reflective structural colors, further enabling full-color displays, high-resolution patterning, and good pattern compatibility. This aims to address the pain points of existing materials, such as narrow color gamuts and incompatibility with general patterning methods.

[0005] However, the aforementioned methods mostly focus on photoluminescence or reflective pattern design and material construction, and there is still a significant gap compared to achieving true electroluminescence panel-level integration. For example, key issues such as the design of the electric drive structure, pixel electrode arrangement, long-term device stability, crosstalk suppression of the left and right circular polarization channels, and programmable displays under high-frequency driving still need to be systematically addressed. Meanwhile, while existing research on circularly polarized (CPL) electroluminescent devices proposes using an AC electric field to drive the light-emitting unit, which can improve device stability and simplify the fabrication process to some extent, such methods merely combine the AC-driven light-emitting device with a liquid crystal circular polarization filter unit, failing to achieve integrated functional layer and driving structure.

[0006] In summary, developing a display panel that can simultaneously solve key technical problems in existing technologies, such as poor circular polarization asymmetry of electroluminescence, difficulty in precise control of dynamic pixels, high difficulty in array integration, and insufficient device stability, has become an important issue that urgently needs to be addressed in this field. Summary of the Invention

[0007] To address the aforementioned problems in the prior art, this invention provides a self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure and its fabrication method. The pixel / emitting unit employs a semi-injection stacked structure. Circular polarization selection and modulation are achieved by introducing a cholesteric liquid crystal polymer layer (CLCP) between the transparent electrode and the device functional layer. Combined with the dielectric layer and the semi-injection emitting stack, highly stable, low-crosstalk circularly polarized self-emissive output is obtained.

[0008] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of the present invention: This invention provides a self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure. The display panel includes a substrate, a transparent bridge, a cholesteric liquid crystal polymer layer (CLCP), a dielectric layer, a hole injection layer (HIL), a hole transport layer (HTL), an emissive layer (EML), an electron transport layer (ETL), an electron injection layer (EIL), and electrodes. The cholesteric liquid crystal polymer layer is formed by polymerization and curing of cholesteric liquid crystal monomers, polymerizable liquid crystal monomers, chiral dopants and initiators.

[0009] Furthermore, the substrate comprises any one of glass, quartz, flexible polyethylene terephthalate (PET), and flexible polyimide (PI), and the thickness of the substrate is 0.05-1.1 mm.

[0010] Furthermore, the thickness of the flexible substrate is preferably 25-200 μm, and the thickness is preferably 0.3-0.7 mm when glass or quartz is used as the substrate.

[0011] Furthermore, the transparent bridge comprises any one of indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), graphene, and silver nanowires. The thickness of the transparent bridge is 30-300 nm, the sheet resistance is 5-50 Ω, and the transmittance (visible light) is ≥80%.

[0012] Furthermore, the transparent bridge is preferably indium tin oxide or indium zinc oxide; The thickness of the transparent bridge is preferably 80-180 nm, the sheet resistance is preferably 5-20 Ω, and the transmittance is preferably ≥85%.

[0013] Furthermore, the thickness of the cholesteric liquid crystal polymer layer is 0.5-20 μm.

[0014] Furthermore, the cholesteric liquid crystal polymer layer is a circular polarization selection and modulation layer, and has a single pitch or multi-pitch / gradient pitch structure; The preferred thickness is 1-8 μm; Mean refractive index n av g is 1.45-1.75, preferably 1.50-1.65; The pitch p is 180-500 nm, preferably 220-420 nm, used to cover the visible light selective reflection band, and the center wavelength approximately satisfies λ0≈n. av g·p; The circular polarization selects either left-handed or right-handed chirality; a preferred implementation is to configure different chirities in different pixel areas / different sub-areas, or to use a switching / composite structure to achieve the dual circular polarization display requirement.

[0015] Furthermore, the cholesteric liquid crystal monomer (nematic phase LC) is used to provide a nematic phase matrix and an orientation basis, and the cholesteric liquid crystal monomer includes E7, E48, ZLI-4788, MLC-6815, BL series, 5CB or a mixed system, wherein E7 is preferred; The polymerizable liquid crystal monomer (reactive mesocrystalline, RM) is used to form a polymer network and lock the cholesteric structure; the main crosslinking agent is preferably RM257 (diacrylate), which is combined with monofunctional / bifunctional RMs such as RM82, RM105, RM23, RM32, and RM606 to adjust the crosslinking density and film toughness; the total RM content is 0-10 wt.%, preferably 2-8 wt.%, of which RM257 accounts for 30-100 wt.% of the total RM content; The chiral dopant is used to adjust the pitch and chiral direction, including R / S5011, R811 / S811, CB15, R1011, or highly optically active chiral agents with higher helical twisting force (HTP); the doping amount is 1-5 wt.%, preferably 2.28 wt.% (red), 2.79 wt.% (green), and 3.15 wt.% (blue). The pitch p is adjusted by the type and amount of chiral dopant, thereby setting the center wavelength and bandwidth of the circular polarization selection / reflection band. The initiator is a photoinitiator with a wavelength of 365 nm, 385 nm or 405 nm, including Irgacure 651, 184, 1173, 369, 2959 (water-soluble) or TPO / TPO-L, preferably Irgacure 651; the total initiator dosage is 0.2-1.5 wt.%, preferably 0.3-1.0 wt.%.

[0016] Further, the dielectric layer (insulating layer) comprises any one of PVDF, PVDF copolymers (PVDF-HFP, PVDF-TrFE, PVDF-TrFE-CFE), PI, PVA, Al2O3, SiO2, TiO2, and ZrO2, with a thickness of 30-300 nm, a dielectric constant of 2-60 kHz, and a leakage current density ≤10. -4 A / cm 2 (Defined by device area and driving conditions).

[0017] Furthermore, the dielectric layer is preferably PVDF, PVDF copolymer, or Al2O3, with a thickness preferably of 70-150 nm, a dielectric constant preferably of 8-30 kHz, and a leakage current density preferably ≤10. -5 A / cm 2 .

[0018] Furthermore, the hole injection layer comprises any one of molybdenum trioxide (MoO3), poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), HAT-CN, and nickel oxide, and the thickness of the hole injection layer is 1-30 nm; Furthermore, the hole injection layer is preferably molybdenum trioxide or poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate). If molybdenum trioxide is used, the thickness is preferably 5-30 nm. If poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) is used, the thickness is preferably 20-60 nm.

[0019] Furthermore, the hole transport layer includes any one of TFB, PVK, poly-TPD, NPB and TCTA, and the thickness of the hole transport layer is 10-120 nm.

[0020] Furthermore, the hole transport layer is preferably TFB or poly-TPD, with a thickness preferably of 20-60 nm, and the glass transition temperature and film formation properties preferably meet the requirements for array process stability (e.g., Tg ≥ 80 °C).

[0021] Furthermore, the light-emitting layer includes a quantum dot light-emitting layer or an organic / perovskite light-emitting layer, and the thickness of the light-emitting layer is 10-150 nm.

[0022] Furthermore, the light-emitting layer is preferably a quantum dot light-emitting layer, which is a red, green, or blue quantum dot light-emitting layer, including CdSe-based, InP-based, or perovskite quantum dots; The thickness of the light-emitting layer is preferably 20-80 nm; Emission peak positions: 450–470 nm (blue), 520–540 nm (green), 620–650 nm (red); External quantum efficiency and brightness indices are set according to the material system, with materials having high color purity and high stability being preferred (e.g., quantum dot systems with FWHM≤35 nm).

[0023] Furthermore, the electron transport layer comprises zinc oxide nanoparticles, ZnMgO, TPBi, BPhen, and C. 60 The electron transport layer of any of the / PCBM types has a thickness of 10-120 nm.

[0024] Furthermore, the electron transport layer is preferably zinc oxide nanoparticles or TPBi, and the thickness is preferably 20-60 nm.

[0025] Furthermore, the electron injection layer comprises any one of LiF, Cs2CO3, PEIE / PEI, a two-dimensional material composed of nitrides or carbonitrides (MXene), and Mg:Ag, and the thickness of the electron injection layer is 0.3-10 nm.

[0026] Furthermore, the electron injection layer is preferably LiF or MXene. If LiF is used, the thickness is preferably 0.5-2 nm, and if PEIE is used, the thickness is preferably 1-5 nm.

[0027] Furthermore, the electrode comprises any one of Al, Ag, Au, Cu and ITO / metal composite transparent electrode; The electrode is a coplanar electrode with a thickness of 30-200 nm.

[0028] Furthermore, the metal composite transparent electrode is MoO3 or Ag; If metal reflective electrodes Al, Ag, Au, or Cu are used, the thickness is preferably 50-150 nm. If ITO or metal composite transparent electrodes are used, a transparent oxide layer is added. The electrodes include metal coplanar finger electrodes and transparent coplanar electrodes, preferably metal coplanar finger electrodes; the electrodes can be patterned according to the array driving requirements.

[0029] The second technical solution of the present invention: The present invention also provides a method for fabricating the self-emissive dual-circularly polarized quantum dot display panel based on the semi-injection structure, comprising the following steps: (1) After ultrasonic cleaning and ozone treatment, the substrate with patterned transparent electrical bridge is oriented on the surface of the transparent electrical bridge. (2) Cholesteric liquid crystal monomer, polymerizable liquid crystal monomer, chiral dopant and initiator are mixed and dissolved, and after filtration, degassing, coating and drying, a cholesteric liquid crystal polymer layer is obtained; (3) A dielectric layer, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer and a coplanar electrode are sequentially prepared on the cholesteric liquid crystal polymer layer from bottom to top.

[0030] Further, the specific process of ultrasonic cleaning in step (1) is as follows: the substrate with patterned transparent electrical bridge is ultrasonically cleaned in water, ethanol and isopropanol for 15-30 min each in sequence. Ozone treatment involves UV ozone treatment for 15-30 minutes to increase the surface energy of the substrate with patterned transparent electrical bridges, which is beneficial for subsequent spin coating and spreading. The orientation agent for the orientation treatment is polyimide, and the orientation method is either rubbing orientation or photo-orientation.

[0031] Furthermore, the transparent bridge is a patterned transparent electrode interconnection; The volume concentration of ethanol is 95%, and the volume concentration of isopropanol is 99%. The specific process of the orientation treatment is as follows: an orientation agent (0.5 wt.%) is spin-coated onto the surface of the transparent bridge, and then cured at a temperature of 150-200 ℃ for 30-60 min, resulting in an orientation layer thickness of 20-100 nm; the orientation / isolation primer on the surface of the transparent bridge in this invention can make the CLCP film formation more stable.

[0032] Furthermore, the filtration described in step (2) is performed using a 0.22-0.45 µm PTFE membrane; The degassing process involves standing for 10-30 minutes. The coating process involves first drop coating and then spin coating, wherein the drop coating volume is 50-150 µL per 1×1 inch; the spin coating speed is 500-3000 rpm, and the time is 20-60 s.

[0033] The drying process involves first softening the material, then UV curing polymerization, and finally drying or curing. The softening temperature is 50-80℃, and the time is 2-10 minutes. UV curing polymerization is performed at a wavelength of 365 nm for 5-30 minutes, with a light intensity of 5-20 mW / cm². 2 Then dry or cure by drying at 80-120 ℃ for 5-30 min to improve crosslinking degree and solvent resistance, in preparation for the next step of dielectric layer spin coating.

[0034] Furthermore, the dielectric layer in step (3) is prepared by spin coating or vacuum deposition.

[0035] Furthermore, if PVDF or PVDF copolymer is selected as the dielectric layer material, the preparation method is as follows: PVDF material is mixed with a solvent (including but not limited to one or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), methyl ethyl ketone, or acetone) at a concentration of 50-150 mg / mL, and then stirred at 300-1500 rpm and 50-80 ℃ until completely dissolved to obtain a dielectric layer spin-coating solution. The dielectric layer spin-coating solution is then drop-coated (1×1 inch: 80-200 µL) onto the cholesteric liquid crystal polymer layer, followed by spin-coating at 500-2500 rpm for 10-60 s to form a film. Finally, the film is baked at 60-120 ℃ for 10-30 min to remove the solvent and stabilize the dielectric properties of the dielectric layer. If Al2O3, SiO2, TiO2 or ZrO2 is selected as the dielectric layer material, the dielectric layer is prepared by vacuum deposition (evaporation or sputtering), and the film is formed according to the equipment control rate. If PI is selected as the dielectric layer material, the preparation method is as follows: after the PI precursor solution or PI solution is stirred and mixed evenly, it is deposited on the surface of the cholesteric liquid crystal polymer layer by any one of spin coating, blade coating, slot coating, spraying or vacuum deposition, and then heated and dried or imidized to form the PI dielectric layer. After spin coating, it is pre-baked at 80-150 ℃ and then heat-treated / imidized at 150-300 ℃. If PVA is selected as the dielectric layer material, the preparation method is as follows: PVA is dissolved in deionized water to prepare a PVA solution. After heating and stirring until completely dissolved, the solution is deposited on the surface of the cholesteric liquid crystal polymer layer by any one of spin coating, blade coating, slot coating or spray coating. After heating and drying, a PVA dielectric layer is formed. The film is heated and stirred at 60-95 ℃ and then dried at 50-120 ℃.

[0036] Furthermore, the hole injection layer in step (3) is prepared by vacuum evaporation or spin coating.

[0037] Furthermore, if molybdenum trioxide is selected as the hole injection layer material, the preparation method is vacuum evaporation, specifically: the molybdenum trioxide target is placed in an evaporation boat, and a vacuum is drawn to 10... -5 Torr, with a vapor deposition rate controlled at 0.5 Å / s and a thickness of 5-30 nm, demonstrates good stability. If poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) is selected as the hole injection layer material, the preparation method is spin coating. Specifically, the blend of poly(3,4-ethylenedioxythiophene) and poly(styrene sulfonate) is filtered and then spin-coated onto the dielectric layer at a speed of 2000-5000 rpm for 30-60 s, and then baked at 120 ℃ for 10-30 min. This method is simple and can be regarded as the preferred solution.

[0038] Furthermore, the electron injection layer in step (3) is prepared by vacuum evaporation or spin coating.

[0039] Furthermore, if a two-dimensional material composed of nitrides or carbonitrides is selected as the electron injection layer, the preparation method is spin coating. Specifically, the two-dimensional material composed of nitrides or carbonitrides is dispersed in an ethanol solvent at a concentration of 20 mg / mL to obtain an MXene solution. Then, the MXene solution is spin-coated onto the electron transport layer at a rotation speed of 3000-6000 rpm for 30-60 s, and finally baked at 100 ℃ for 10 min. If LiF is selected as the electron injection layer material, the preparation method is vacuum evaporation, specifically: the evaporation rate is 0.1-0.5 Å / s.

[0040] Furthermore, the coplanar electrode described in step (3) is obtained by patterning after metal evaporation through a mask or spin coating of transparent conductive material.

[0041] Furthermore, when the electrode is a coplanar metal finger electrode (preferred), the fabrication method is as follows: A coplanar electrode pattern is formed on the electron injection layer using a metal mask or photolithography. The finger width or spacing is 5-200 µm, determined according to the pixel size. Then, the metal reflective electrode material target is placed inside an evaporation boat, and a vacuum is drawn to 10... -6 -10 -5 Torr, controlling the evaporation rate at 0.5-5 Å / s and the deposition thickness at 50-150 nm, forms a coplanar electrode. Finally, after cooling, it is filled with inert gas to atmospheric pressure to obtain the final product. When the electrode is a transparent coplanar electrode, the fabrication method is as follows: a transparent conductive film is prepared on the substrate surface using one of the following methods: magnetron sputtering, electron beam evaporation, pulsed laser deposition, or solution coating. When the transparent conductive film is an ITO film, magnetron sputtering is preferred. When the transparent conductive film is a metal composite transparent electrode, spin coating, spray coating, blade coating, or printing is preferred. Subsequently, the coplanar electrode pattern is obtained using laser etching, photolithography, or mask patterning.

[0042] The self-emissive dual-circularly polarized quantum dot display panel prepared by this invention is driven by AC or pulse drive. The frequency is 0.5-200 kHz, and the three-dimensional display is preferably ≥1 kHz, more preferably 1-20 kHz; The voltage is 20-300 V, which is related to the thickness of the dielectric layer and the pixel area, and is preferably 50-200 V. The display mode enables high-frequency alternating display of the left and right channels, and circular polarization selection and modulation are completed through the CLCP layer, thereby improving the stability and comfort of the 3D display.

[0043] The beneficial effects of this invention compared to the prior art are as follows: The display panel studied in this invention includes a cholesteric liquid crystal polymer (CLCP) layer with left and right chiral partitions and coplanar electrodes, enabling the separation of dual circularly polarized light output and 3D display channels. It simultaneously provides left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) channels on the same panel. This invention achieves controllable output and pixel-level dynamic display of the left and right circularly polarized channels by integrating the cholesteric liquid crystal polymer layer and dielectric layer within the panel and employing coplanar electrodes in conjunction with high-frequency AC drive. This invention also utilizes a quantum dot emitting layer to meet the requirements of full-color display.

[0044] This invention employs a semi-injection structure and introduces a dielectric layer, which reduces the device's dependence on DC carrier injection, achieves isolation and buffering of charge or electric field, effectively suppresses leakage and local breakdown risks, reduces the stringent requirements for fine charge balance, broadens the process window, and significantly improves the reliability, uniformity, and lifespan of quantum dot light-emitting devices. It also improves the problems of overcurrent, heat generation, lifetime decay, and pixel unevenness caused by carrier injection imbalance and interface defects in traditional quantum dot electroluminescence (injection-type QLED / OLED).

[0045] This invention achieves the selection and separation of the circular polarization channel through the coordinated design of liquid crystal polarization filtering and device output, decoupling the light-emitting layer and the polarization control layer. This avoids the material and process difficulties caused by introducing complex chiral structures within the light-emitting layer, facilitating separate optimization and parameter coordination, and improving the scalability and manufacturing compatibility of the structure. Simultaneously, since the circular polarization output path is achieved through device emission and liquid crystal selection, it can reduce the ineffective absorption loss of traditional polarizer links to a certain extent, improving the overall light extraction efficiency and system energy efficiency.

[0046] This invention integrates circularly polarized output with a self-emissive panel more tightly, which helps to reduce the number of additional components and assembly steps in the terminal form. This not only reduces the thickness and weight of the display panel, but also reduces system-level power consumption and BOM cost. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a structural diagram of the self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure in Embodiment 1 of the present invention; The components are: 1. Substrate; 2. Transparent electrical bridge; 3. Cholesteric liquid crystal polymer layer; 4. Dielectric layer; 5. Hole injection layer; 6. Hole transport layer; 7. Light-emitting layer; 8. Electron transport layer; 9. Electron injection layer; 10. Electron electrode. Figure 2 This is a circular dichroism (CD) signal image at 610 nm for a self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure in Embodiment 1 of the present invention. Figure 3 This is a graph showing the circularly polarized electroluminescence (CPEL) and asymmetry factor g value of the self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure in Embodiment 1 of the present invention at 610 nm. Figure 4 This is a physical image of the full-color circularly polarized self-emissive panel of the self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure in Embodiment 3 of the present invention. Detailed Implementation

[0049] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0050] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0051] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0052] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0053] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0054] This invention provides a method for fabricating a self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure, comprising the following steps: (1) After ultrasonic cleaning and ozone treatment, the substrate with patterned transparent electric bridge is oriented on the surface of the transparent electric bridge. (2) Cholesteric liquid crystal monomer, polymerizable liquid crystal monomer, chiral dopant and initiator are mixed and dissolved, and after filtration, degassing, coating and drying, a cholesteric liquid crystal polymer layer is obtained; (3) A dielectric layer, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a coplanar electrode are prepared sequentially from bottom to top on the cholesteric liquid crystal polymer layer.

[0055] In a further embodiment, the specific process of ultrasonic cleaning in step (1) is as follows: the substrate with patterned transparent electrical bridge is ultrasonically cleaned in deionized water, ethanol (95% v / v), and isopropanol (99% v / v) for 15-30 min each. Ozone treatment involves UV ozone treatment for 15-30 minutes to increase the surface energy of the substrate with patterned transparent electrical bridges, which is beneficial for subsequent spin coating and spreading. The specific process of orientation treatment is as follows: the orientation agent polyimide (0.5 wt.%) is spin-coated onto the surface of the transparent bridge, and then cured at a temperature of 150-200 ℃ for 30-60 min, resulting in an orientation layer thickness of 20-100 nm; the orientation method is triboelectric orientation or photo-orientation. The present invention oriented / isolated the base coat on the surface of the transparent bridge, which can make the CLCP film formation more stable.

[0056] In a further embodiment, the filtration in step (2) is performed using a 0.22-0.45 µm PTFE membrane. Degassing is performed by allowing the mixture to stand for 10-30 minutes. The coating process involves first drop coating and then spin coating. The drop coating volume is 50-150 µL per 1×1 inch; the spin coating speed is 500-3000 rpm; and the time is 20-60 s.

[0057] The drying process involves first softening and baking, then UV curing polymerization, and finally drying or curing. The softening and baking temperature is 50-80 ℃ for 2-10 min; the UV curing polymerization is performed at a wavelength of 365 nm for 5-30 min with a light intensity of 5-20 mW / cm². 2 Then dry or cure by drying at 80-120 ℃ for 5-30 min to improve crosslinking degree and solvent resistance, in preparation for the next step of dielectric layer spin coating.

[0058] In a further embodiment, the dielectric layer in step (3) is prepared by spin coating or vacuum deposition; If PVDF or PVDF copolymer is selected as the dielectric layer material, the preparation method is as follows: Mix PVDF material with solvent (solvents include, but are not limited to, one or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), methyl ethyl ketone or acetone) at a concentration of 50-150 mg / mL, and then stir at 300-1500 rpm and 50-80 ℃ until completely dissolved to obtain a dielectric layer spin-coating solution. Then, drop-coat (1×1 inch: 80-200 µL) onto the cholesteric liquid crystal polymer layer, spin-coat at 500-2500 rpm for 10-60 s to form a film, and finally bake at 60-120 ℃ for 10-30 min to remove the solvent and stabilize the dielectric properties of the dielectric layer. If Al2O3, SiO2, TiO2 or ZrO2 is selected as the dielectric layer material, the dielectric layer is prepared by vacuum deposition (evaporation or sputtering, preferably atomic layer deposition or sputtering), and the film is formed according to the equipment control rate. If PI is selected as the dielectric layer material, the preparation method is as follows: After the PI precursor solution or PI solution is stirred and mixed evenly, it is deposited on the surface of the cholesteric liquid crystal polymer layer by any one of the following methods: spin coating, blade coating, slot coating, spray coating or vacuum deposition. Then, it is heated and dried or imidized to form the PI dielectric layer. After spin coating, it is pre-baked at 80-150 ℃ and then heat-treated / imidized at 150-300 ℃. If PVA is selected as the dielectric layer material, the preparation method is as follows: PVA is dissolved in deionized water to prepare a PVA solution. After heating and stirring until completely dissolved, it is deposited on the surface of the cholesteric liquid crystal polymer layer by any one of spin coating, blade coating, slot coating or spray coating. After heating and drying, a PVA dielectric layer is formed. The film is heated and stirred at 60-95 ℃ and then dried at 50-120 ℃.

[0059] In a further embodiment, the hole injection layer in step (3) is prepared by vacuum evaporation or spin coating; If molybdenum trioxide is selected as the hole injection layer material, the preparation method is vacuum evaporation, specifically: the molybdenum trioxide target is placed in an evaporation boat, and a vacuum is drawn to 10... -5 Torr, with a vapor deposition rate controlled at 0.5 Å / s and a thickness of 5-30 nm, demonstrates good stability. If poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) is selected as the hole injection layer material, the preparation method is spin coating. Specifically, the blend of poly(3,4-ethylenedioxythiophene) and poly(styrene sulfonate) is filtered and then spin-coated onto the dielectric layer at a speed of 2000-5000 rpm for 30-60 s, and then baked at 120 ℃ for 10-30 min. This method is simple and can be regarded as the preferred solution.

[0060] In a further embodiment, when the material of the hole transport layer in step (3) is selected as TFB, the preparation method is as follows: TFB is dissolved in chlorobenzene at a concentration of 8 mg / mL, stirred at 90 °C and 1500 rpm until completely dissolved, then filtered through a 0.45 μm PTFE filter membrane, and then dropped onto the hole injection layer at a volume of 50-150 μL per 1×1 inch. Then, the hole transport layer film is obtained by spin coating at 3000 rpm for 30 s, and finally baked at 80-120 °C for 10-30 min.

[0061] In a further embodiment, when the light-emitting layer in step (3) is a quantum dot light-emitting layer, the preparation method is as follows: mix quantum dots with octane and sonicate for 20 min to obtain a uniform dispersion, then drop-coat it onto the hole transport layer at a volume of 50-120 μL per 1×1 inch, then spin-coat it at 2000 rpm for 30 s to form a film, and finally dry it at 90 ℃ for 10 min to remove the octane. Red, green, and blue quantum dot layers can be prepared in the same way; multi-color pixels can be achieved by partition printing, mask spin coating, or inkjet printing.

[0062] In a further embodiment, when the electron transport layer material in step (3) is zinc oxide nanoparticles, the preparation method is as follows: zinc oxide nanoparticles are dispersed in ethanol at 20 mg / mL, and then spin-coated onto the light-emitting layer at a speed of 3000 rpm for 40 s to obtain a uniform electron transport layer film. Finally, the film is baked at 60-100 ℃ for 5-20 min to improve the density and stability of the film.

[0063] In a further embodiment, the electron injection layer in step (3) is prepared by vacuum evaporation or spin coating; If a two-dimensional material composed of nitrides or carbonitrides is selected as the electron injection layer, the preparation method is spin coating. Specifically, the two-dimensional material composed of nitrides or carbonitrides is dispersed in an ethanol solvent at a concentration of 20 mg / mL to obtain an MXene solution. Then, it is spin-coated onto the electron transport layer at a rotation speed of 3000-6000 rpm for 30-60 s. Finally, it is baked at 100 °C for 10 min. If LiF is selected as the electron injection layer material, the preparation method is vacuum evaporation, specifically: the evaporation rate is 0.1-0.5 Å / s.

[0064] In a further embodiment, the planar electrode in step (3) is obtained by patterning after metal evaporation through a mask or spin coating of a transparent conductive material. When the electrode is a coplanar metal finger electrode (preferred), the fabrication method is as follows: A coplanar electrode pattern is formed on the electron injection layer using a metal mask or photolithography. The finger width or spacing is 5-200 µm, determined according to the pixel size. Then, the metal reflective electrode material target is placed inside an evaporation boat, and a vacuum is drawn to 10... -6 -10 -5 Torr, controlling the evaporation rate at 0.5-5 Å / s and the deposition thickness at 50-150 nm, forms a coplanar electrode. Finally, after cooling, it is filled with inert gas to atmospheric pressure to obtain the final product. When the electrode is a transparent coplanar electrode, the fabrication method is as follows: a transparent conductive film is prepared on the substrate surface using one of the following methods: magnetron sputtering, electron beam evaporation, pulsed laser deposition, or solution coating. When the transparent conductive film is an ITO film, magnetron sputtering is preferred. When the transparent conductive film is a metal composite transparent electrode, spin coating, spray coating, blade coating, or printing is preferred. Subsequently, the coplanar electrode pattern is obtained using laser etching, photolithography, or mask patterning.

[0065] Example 1 A self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure (structure as follows) Figure 1 As shown, from bottom to top, the layers are: substrate (1), transparent bridge (2), cholesteric liquid crystal polymer layer (3), dielectric layer (4), hole injection layer (5), hole transport layer (6), light-emitting layer (7), electron transport layer (8), electron injection layer (9), and coplanar electrode (10). The cholesteric liquid crystal polymer layer is represented by (3) and (3′), which means that the cholesteric liquid crystal polymer layer corresponds to two different chiral directions. These two directions do not necessarily have to appear at the same time. In specific implementation, only left-handed (3), only right-handed (3′), or both left and right directions can be set. Figure 1 The purpose of using this designation is to distinguish between implementations with different spin directions.

[0066] The above-mentioned method for fabricating a self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure includes the following steps: (1) Substrate and transparent bridge: The substrate with patterned transparent bridges was ultrasonically cleaned in deionized water, ethanol (95% v / v), and isopropanol (99% v / v) for 20 min each, and then treated with ultraviolet ozone for 20 min. 0.5 wt.% polyimide was spin-coated onto the surface of the transparent bridge at 3000 rpm for 30 s, and then cured at 180 ℃ for 45 min. Unidirectional triboelectric orientation was performed (pressure 100-300 g / cm). 2 (Speed ​​5-20 cm / s).

[0067] (2) CLCP partitioning patterning: Nematic liquid crystal E7, chiral dopant (R / S5011, doping concentration 2.3% (corresponding to the red light (610 nm) photonic bandgap), polymerizable liquid crystal monomer (RM257, addition amount 30 wt.%), and photoinitiator (Irgacure651, 0.5 wt.%) were mixed and stirred until completely dissolved. After filtration through a 0.45 µm PTFE filter membrane, the mixture was allowed to stand for 15 min to remove bubbles. Then, it was drop-coated onto a transparent bridge at a volume of 100 µL per 1×1 inch. After spin-coating at 1200 rpm for 40 s, it was soft-baked at 60 °C for 5 min and cured in a UV environment with a wavelength of 365 nm for 10 min at a light intensity of 10 mW / cm². 2 Finally, the mixture was baked at 100 °C for 10 min. After baking, a patterned circularly polarized liquid crystal layer was prepared by a mask-assisted secondary spin coating process. First, a left-handed cholesteric liquid crystal polymer was spin-coated and UV cured. Then, the cured area was blocked by a mask, and a right-handed cholesteric liquid crystal polymer was spin-coated and cured in the adjacent pixel area to obtain a circularly polarized liquid crystal layer with alternating left and right chirality.

[0068] (3) Dielectric layer: Mix PVDF and DMF at 100 mg / mL, and then stir at 1000 rpm and 60 °C until completely dissolved to obtain a dielectric layer spin-coating solution. Then drop-coat (1×1 inch: 80-200 µL) onto the CLCP layer, and then spin-coat at 1500 rpm for 30 s to form a film. Finally, bake at 100 °C for 20 min to remove DMF.

[0069] (4) HIL layer: Place the molybdenum trioxide target in the evaporation boat and evacuate to 10°C. -5 Torr was used to control the evaporation rate at 0.5 Å / s to obtain a HIL layer with a thickness of 10 nm.

[0070] (5) HTL layer: TFB was dissolved in chlorobenzene at 8 mg / mL and stirred at 90 °C and 1500 rpm until completely dissolved. After filtration through a 0.45 μm PTFE filter membrane, the solution was dropped onto the HIL layer at a volume of 100 μL per 1×1 inch. The solution was then spin-coated at 3000 rpm for 30 s to obtain the HTL layer film. Finally, the film was baked at 100 °C for 20 min.

[0071] (6) EML layer: Red light (610 nm) quantum dots were mixed with n-octane and sonicated for 20 min to obtain a uniform dispersion. Then, 100 μL per 1×1 inch was drop-coated onto the HTL layer. The film was then spin-coated at 2000 rpm for 30 s and finally dried at 90 °C for 10 min to remove the n-octane.

[0072] (7) ETL layer: Zinc oxide nanoparticles were dispersed in ethanol at 20 mg / mL, and then spin-coated onto the EML layer at 3000 rpm for 40 s to obtain a uniform ETL layer film. Finally, the film was baked at 80 ℃ for 10 min.

[0073] (8) EIL layer: LiF was deposited on the ETL layer by vacuum evaporation at a rate of 0.2 Å / s.

[0074] (9) Coplanar electrode fabrication: Two sets of finger electrodes were used to correspond to the left and right channel drives, respectively. The finger electrodes were formed using a metal mask with a finger width of 50 µm and a spacing of 50 µm. The Ag deposition thickness was 100 nm, and the vacuum temperature was 110 °C. -5 Torr, evaporation rate 1 Å / s.

[0075] The display panel prepared in Example 1 was characterized by testing the circular dichroism (CD) of the cholesteric liquid crystal polymer layer (CLCP) for left-handed and right-handed circularly polarized light, respectively. Figure 2 As shown, the results indicate that under AC driving conditions (peak voltage Vp = 200 V, frequency f = 10 kHz), the semi-injected display panel of Example 1 stably emits red light with a peak position of 610 nm. It exhibits highly symmetrical circular polarization selectivity within the wavelength of 610 nm, effectively realizing the precise separation and balanced response of the left and right chiral channels, and significantly improving the consistency and reliability of the device's polarization output.

[0076] The display panel prepared in Example 1 was further subjected to circularly polarized electroluminescence (CPEL) testing, and the results are as follows: Figure 3 As shown, left-handed and right-handed circularly polarized components can be obtained separately, with their asymmetry factors (g values) both reaching 1.8 (the theoretical upper limit is 2.0). Among them, the g value (also known as the circularly polarized luminescence asymmetry factor) is used to quantitatively characterize the circular polarization purity and chiral selectivity of the luminescence, reflecting the relative intensity difference between the left and right circularly polarized components; the closer the g value is to 2.0, the closer the circularly polarized output is to single chirality and the higher the polarization purity.

[0077] Example 2 A method for preparing a self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure differs from Example 1 in that: in step (3), the dielectric layer material is Al2O3, and the control rate is 1 Å / s; Step (8) The material used for the EIL layer is MXene. MXene is dispersed in ethanol at 20 mg / mL, and then spin-coated onto the ETL layer at 5000 rpm for 40 s. Finally, it is baked at 100 ℃ for 10 min. The materials and preparation methods for the remaining layers are the same as in Example 1.

[0078] The lifespan of the display panel prepared in Example 2 was tested. The results showed that under continuous illumination at 120 V and 5 kHz, the T50 increased by 10% and the maximum brightness decreased by 30%. The lifespan of the display panel prepared in this invention was significantly improved.

[0079] Example 3 A method for fabricating a self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure differs from Example 1 in that: in step (6), the EML layer is an RGB (red, green, blue) three-color quantum dot pixel array, and the RGB quantum dot array is spin-coated in a mask partition, as shown below. Figure 4 As shown, the specific preparation method is as follows: (1) Create three sets of alignment masks (corresponding to the red, green, and blue sub-pixel windows respectively); (2) Red quantum dots: Mask 1 covers the non-red area, drop-coat quantum dots (20 mg / mL), spin-coat at 2000 rpm for 30 s, and finally dry at 90 ℃ for 10 min.

[0080] (3) Green quantum dots: Replace mask 2, align and repeat spin coating and drying.

[0081] (4) Blue quantum dots: Replace mask 3, align and repeat spin coating and drying.

[0082] Comparative Example 1 A method for fabricating a self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure, differing from Example 1 in that the dielectric layer is removed; The remaining structure and manufacturing method of the display panel are the same as in Example 1.

[0083] The results showed that the leakage current of the display panel prepared in Comparative Example 1 increased sharply in the voltage range of 80-120 V, and local breakdown occurred. The brightness drift was obvious and the stable lighting time was significantly shortened, which proved the criticality of the dielectric layer in the present invention for the entire display panel.

[0084] Comparative Example 2 A method for fabricating a self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure, differing from Example 1 in that the CLCP layer is removed; The remaining structure and manufacturing method of the display panel are the same as in Example 1.

[0085] The results showed that the display panel g prepared in Comparative Example 2 was superior. EL ≈0 (no obvious LCP / RCP difference); effective circular polarization channel separation cannot be formed under high-frequency alternating drive, proving that the CLCP layer is the key to circular polarization output in this invention.

[0086] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure, characterized in that, The display panel includes a substrate, a transparent bridge, a cholesteric liquid crystal polymer layer, a dielectric layer, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and electrodes; The cholesteric liquid crystal polymer layer is formed by polymerization and curing of cholesteric liquid crystal monomers, polymerizable liquid crystal monomers, chiral dopants and initiators.

2. The self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure according to claim 1, characterized in that, The substrate comprises any one of glass, quartz, flexible polyethylene terephthalate, and flexible polyimide, and the thickness of the substrate is 0.05-1.1 mm. The transparent bridge includes any one of indium tin oxide, indium zinc oxide, aluminum-doped zinc oxide, graphene, and silver nanowires. The thickness of the transparent bridge is 30-300 nm, the sheet resistance is 5-50 Ω, and the transmittance is ≥80%.

3. The self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure according to claim 1, characterized in that, The thickness of the cholesteric liquid crystal polymer layer is 0.5-20 μm.

4. The self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure according to claim 1, characterized in that, The dielectric layer comprises any one of PVDF, PVDF copolymer, PI, PVA, Al2O3, SiO2, TiO2, and ZrO2, with a thickness of 30-300 nm, a dielectric constant of 2-60 kHz, and a leakage current density ≤10. -4 A / cm 2 ; The hole injection layer comprises any one of molybdenum trioxide, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), HAT-CN, and nickel oxide, and the thickness of the hole injection layer is 1-30 nm. The hole transport layer includes any one of TFB, PVK, poly-TPD, NPB and TCTA, and the thickness of the hole transport layer is 10-120 nm. The light-emitting layer includes a quantum dot light-emitting layer or an organic / perovskite light-emitting layer, and the thickness of the light-emitting layer is 10-150 nm. The electron transport layer comprises zinc oxide nanoparticles, ZnMgO, TPBi, BPhen, and C. 60 Any of the / PCBM types, wherein the thickness of the electron transport layer is 10-120 nm; The electron injection layer comprises any one of LiF, Cs2CO3, PEIE / PEI, two-dimensional materials composed of nitrides or carbonitrides, and Mg:Ag, and the thickness of the electron injection layer is 0.3-10 nm.

5. The self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure according to claim 1, characterized in that, The electrode includes any one of Al, Ag, Au, Cu and ITO / metal composite transparent electrode; The electrode is a coplanar electrode with a thickness of 30-200 nm.

6. A method for fabricating a self-emissive dual-circularly polarized quantum dot display panel based on a semi-injection structure as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) After ultrasonic cleaning and ozone treatment, the substrate with patterned transparent electrical bridge is oriented on the surface of the transparent electrical bridge. (2) Cholesteric liquid crystal monomer, polymerizable liquid crystal monomer, chiral dopant and initiator are mixed and dissolved, and after filtration, degassing, coating and drying, a cholesteric liquid crystal polymer layer is obtained; (3) A dielectric layer, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer and a coplanar electrode are sequentially prepared on the cholesteric liquid crystal polymer layer from bottom to top.

7. The preparation method according to claim 6, characterized in that, The specific process of ultrasonic cleaning in step (1) is as follows: the substrate with patterned transparent electrical bridge is ultrasonically cleaned in water, ethanol and isopropanol for 15-30 min each in sequence. The orientation agent for the orientation treatment is polyimide, and the orientation method is either rubbing orientation or photo-orientation.

8. The preparation method according to claim 6, characterized in that, The dielectric layer in step (3) is prepared by spin coating or vacuum deposition; Both the hole injection layer and the electron injection layer are prepared by vacuum evaporation or spin coating.

9. The preparation method according to claim 6, characterized in that, The coplanar electrode described in step (3) is obtained by patterning after metal evaporation through a mask or spin coating of transparent conductive material.

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