Micro-qled chip for projection optical engine, preparation method thereof, and projection optical engine

Abstract

This invention relates to the field of semiconductor technology, disclosing a Micro-QLED chip for a projection optical engine, its fabrication method, and a projection optical engine, aiming to replace expensive Micro-LED chips and solve the problem of lead-based quantum dot materials easily polluting the environment. The solution mainly includes: a Micro-QLED chip for a projection optical engine, its fabrication method, and a projection optical engine. The Micro-QLED chip, from bottom to top, includes: a substrate with transparent electrodes, a hole injection layer, a hole transport layer, a quantum dot emitting layer, an electron transport layer, and a TFT driving circuit board with metal electrodes; the quantum dot emitting layer is made of lead-free copper-based mixed halide perovskite quantum dot material; the projection optical engine includes a three-color Micro-QLED chip, a light-combining prism, and a projection lens. This invention reduces chip fabrication costs through improved processes, enhances chip luminous efficiency and color purity, and avoids environmental pollution caused by lead-containing materials, making it suitable for projection display products.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically to a Micro-QLED chip for a projection optical engine, its fabrication method, and the projection optical engine. Background Technology

[0002] Projection technology has undergone three generations of evolution. The first generation used cathode ray tubes (CRTs) as imaging devices. Phosphors within the CRTs were amplified and focused by a light-emitting system under high voltage to display a color image on a screen. The second generation used liquid crystal panels (LCDs) for image modulation, which was then transmitted and displayed via a projection system. With increasing demands for product comfort, projection technology has evolved beyond the second generation towards higher brightness, higher quality, and miniaturization. Micro-projectors represent the main development direction of the third generation, characterized by their small size, large display size, and high light efficiency. Currently, the most widely used projection systems are Liquid Crystal Display (LCD), Liquid Crystal on Silicon (LCoS), and Digital Light Processing (DLP). Because these three systems use passive light-emitting chips, their light utilization is very low. Furthermore, LCD screens are large, LCoS suffers from poor heat dissipation, and the production cost of the core component of DLP—the Digital Micromirror Device (DMD) chip—is high. In general, traditional projection optical engines, which use passive light-emitting chips as the image source, must include an additional light source and front-end illumination path, resulting in poor flexibility and large size. Moreover, some projector products use LEDs as the light source and color filters to achieve full color, but because the filter has a wide spectral bandwidth, the purity of the filtered primary colors is not high, leading to a relatively limited color gamut.

[0003] In recent years, Micro-LED, considered a next-generation display technology, has received widespread attention. Micro-LED displays are primarily based on inorganic gallium nitride (GaN)-based light-emitting diodes, possessing numerous advantages such as self-emission, fast response speed (on the order of nanoseconds), high contrast, high resolution, high reliability, long lifespan, low power consumption, high luminous efficiency, and excellent color purity. Utilizing the high resolution and brightness of Micro-LEDs, micro-display chips can be fabricated for projection, greatly facilitating daily entertainment and work. This makes Micro-LED projection a promising trend in projection display technology.

[0004] Currently, to achieve color in Micro-LED projection display technology, three Micro-LED microdisplays can be used to display red, green, and blue images individually, and then colorization can be achieved through a light-combining prism; alternatively, colorization can be achieved using a single stacked Micro-LED. However, the current Micro-LED chip manufacturing process is quite complex, resulting in high production costs. Moreover, the performance of red Micro-LEDs lags far behind that of green and blue Micro-LEDs. Therefore, both methods of achieving colorization using three Micro-LED microdisplays and single stacked Micro-LEDs suffer from drawbacks such as high cost and difficulty in color matching.

[0005] Micro-QLEDs, which have matured in recent years, use metal halide quantum dots as the light-emitting layer material. Through component modulation, the emission spectrum can be arbitrarily tuned across the entire visible spectrum. By selecting appropriate halogen ratios, high-purity red, green, and blue self-emissive devices can be fabricated, thus Micro-QLEDs have broad prospects in the future display field. However, many perovskite quantum dot materials currently used contain lead (Pb), an element harmful to the environment; furthermore, the current quantum dot synthesis process based on the hot-injection method is relatively complex and costly. Therefore, the commercial development of lead halide perovskite quantum dot-based LED devices is hindered by their inherent toxicity and the complexity of the synthesis process. Summary of the Invention

[0006] This invention aims to address the problems of high cost of existing Micro-LED chips and environmental pollution caused by lead-based halide perovskite quantum dot-based light-emitting diode devices. It proposes a Micro-QLED chip for projection optical engines, its fabrication method, and projection optical engine.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0008] In the first aspect, a Micro-QLED chip for projection optical engine is proposed, wherein the Micro-QLED chip comprises, from bottom to top: a substrate with transparent electrodes, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and a TFT driving circuit board with metal electrodes.

[0009] The quantum dot light-emitting layer is composed of a quantum dot color conversion film. The pixel arrangement on the quantum dot color conversion film corresponds one-to-one with the driving array of the TFT driving circuit board. The quantum dot color conversion film is made of lead-free copper-based mixed halide perovskite quantum dot material.

[0010] Furthermore, the quantum dot color conversion film has a conversion wavelength of 450-780nm, a full width at half maximum (FWHM) of ≤40nm, and a film thickness of ≤100nm.

[0011] Furthermore, the substrate is a flexible substrate made of glass, silicon wafer, metal, quartz, ITO-coated polyethylene terephthalate film, or polyetherimide flexible substrate.

[0012] Secondly, a method for fabricating a Micro-QLED chip for a projection optical engine is proposed, the method comprising:

[0013] Step 1: Fabricate a transparent electrode on the substrate to form a substrate with a transparent electrode attached;

[0014] Step 2: Spin-coat the hole injection layer material doped with polymer crosslinking agent onto the transparent electrode to form a hole injection layer, and sinter it in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius.

[0015] Step 3: Spin-coat the hole transport layer material onto the hole injection layer to form a hole transport layer, and sinter it in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius.

[0016] Step 4: Prepare a quantum dot solution with a concentration of 50-100 mg / mL, spin-coat it onto the hole transport layer to form a quantum dot light-emitting layer, and sinter it in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius.

[0017] Step 5: Prepare a solution of ZnO particles, TiO2 particles or ZnO:MgO particles at a concentration of 50-100 mg / mL, and spin-coat it onto the quantum dot light-emitting layer to form an electron transport layer. The spin-coating rate is 1000-5000 rpm / min, the time is 30-40 seconds, and the layer is sintered in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius.

[0018] Step 6: Deposit the metal target onto the TFT driving circuit board to form a TFT driving circuit board with metal electrodes.

[0019] Step 7: Mount the TFT driving circuit board with metal electrodes onto the electron transport layer and polish the back side of the substrate with transparent electrodes.

[0020] Further, in step 1, the fabrication of the transparent electrode on the substrate specifically includes:

[0021] A solution of gold, silver, or platinum nanowires is repeatedly sprayed and printed onto the substrate; or

[0022] Indium tin oxide, fluorine-doped tin oxide, or aluminum-doped zinc oxide are prepared on the substrate by sputtering.

[0023] Further, in step 4, the preparation of a quantum dot solution with a concentration of 50-100 mg / mL specifically includes:

[0024] Step 41: Dissolve one or more of the following solids (0.1-1.5 mmol cesium iodide, 0.1-1.5 mmol cuprous iodide, 0.1-1.5 mmol cesium bromide, 0.1-1.5 mmol cuprous bromide, 0.1-1.5 mmol cesium chloride, and 0.1-1.5 mmol cuprous chloride) in 1-10 mL of dimethyl sulfoxide solution and stir thoroughly to obtain a precursor solution;

[0025] Step 42: Rapidly add the antisolvent dropwise to the precursor solution under vigorous stirring;

[0026] Step 43: Centrifuge the obtained solution at 3000-10000 rpm for 5-10 minutes, discard the supernatant, and redissolve the precipitate in 1-10 mL of dimethyl sulfoxide solution to obtain a quantum dot solution with a concentration of 50-100 mg / mL.

[0027] Furthermore, the crosslinking agent is polyethylene glycol, polypropylene glycol, trimethylolpropane, or trimethylolethane, and the metal target is gold, silver, platinum, or aluminum.

[0028] Furthermore, the quantum dot solution is a blue quantum dot solution, a green quantum dot solution, or a red quantum dot solution.

[0029] Thirdly, a projection optical engine is proposed, which includes three Micro-QLED chips as described in the first aspect for the projection optical engine. The quantum dot light-emitting layers of the three Micro-QLED chips are blue quantum dot light-emitting layer, green quantum dot light-emitting layer and red quantum dot light-emitting layer, respectively. The projection optical engine also includes a light combining prism and a projection lens.

[0030] The three Micro-QLED chips combine the light beams from their respective display areas into a single optical path using a beam combining prism, and then project the image through a projection lens.

[0031] Furthermore, the three Micro-QLED chips are fabricated using the Micro-QLED chip fabrication method for projection optical engines as described in the second aspect.

[0032] The beneficial effects of this invention are as follows: The Micro-QLED chip and its fabrication method for projection optical engines described in this invention address the inherent toxicity of traditional lead-based perovskite quantum dots and the complexity of the hot-injection synthesis method. By employing non-lead-based copper-based mixed halide perovskite quantum dots prepared using a room-temperature synthesis method as the light-emitting layer material for QLEDs, this invention achieves coordinated emission of red, green, and blue colors while avoiding environmental pollution and solving the high cost problem caused by complex fabrication processes. Furthermore, addressing the low light utilization efficiency of projection optical engines, this invention uses actively emitting micro-quantum dot light-emitting diode devices (Micro-QLEDs) to replace traditional passive light-emitting devices such as LCDs, DMDs, LCoS, and the relatively expensive Micro-LEDs, improving luminous efficiency and color purity. This, in turn, enhances the flexibility of the projection optical engine and reduces its size and cost. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the Micro-QLED chip used for projection optical engine according to an embodiment of the present invention;

[0034] Figure 2 This is a schematic flowchart illustrating the fabrication method of the Micro-QLED chip for a projection optical engine according to an embodiment of the present invention.

[0035] Figure 3 This is a schematic diagram of the projection optical engine described in an embodiment of the present invention;

[0036] Explanation of reference numerals in the attached figures:

[0037] 1-Substrate; 2-Hole injection layer; 3-Hole transport layer; 4-Quantum dot light-emitting layer; 5-Electron transport layer; 6-TFT driver circuit board; 7-Monochrome Micro-QLED chip; 8-Color combining prism; 9-Projection lens; 10-Screen. Detailed Implementation

[0038] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0039] Firstly, this invention aims to avoid the environmental pollution caused by the inherent toxicity of traditional lead-based perovskite quantum dots by proposing a Micro-QLED chip for projection optical engines. The main technical solution includes: the Micro-QLED chip, from bottom to top, comprising: a substrate with transparent electrodes, a hole injection layer, a hole transport layer, a quantum dot emitting layer, an electron transport layer, and a TFT driving circuit board with metal electrodes; the quantum dot emitting layer is composed of a quantum dot color conversion film, and the pixel arrangement on the quantum dot color conversion film corresponds one-to-one with the driving array of the TFT driving circuit board; the quantum dot color conversion film is made of a lead-free copper-based mixed halide perovskite quantum dot material. Because this invention uses lead-free copper-based mixed halide perovskite quantum dots as the emitting layer material of the QLED, it avoids the environmental pollution caused by the inherent toxicity of traditional lead-based perovskite quantum dots.

[0040] Building upon the first aspect, this invention also proposes a method for fabricating a Micro-QLED chip for a projection optical engine. The main technical solution includes: fabricating a transparent electrode on a substrate to form a substrate with the transparent electrode; spin-coating a hole injection layer material doped with a polymer crosslinking agent onto the transparent electrode to form a hole injection layer, and sintering it in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius; spin-coating a hole transport layer material onto the hole injection layer to form a hole transport layer, and sintering it in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius; preparing a quantum dot solution with a concentration of 50-100 mg / mL, and spin-coating it onto the hole transport layer to form a quantum dot light-emitting layer. The process involves sintering under nitrogen atmosphere for 10-30 minutes at a temperature of 100-200 degrees Celsius. A solution of ZnO particles, TiO2 particles, or ZnO:MgO particles at a concentration of 50-100 mg / mL is prepared and spin-coated onto the quantum dot luminescent layer to form an electron transport layer. The spin-coating rate is 1000-5000 rpm / min for 30-40 seconds, followed by drying at 100-200 degrees Celsius. The solution is then sintered under nitrogen atmosphere for 10-30 minutes at a temperature of 100-200 degrees Celsius. A metal target is deposited onto a TFT driving circuit board to form a TFT driving circuit board with metal electrodes. The TFT driving circuit board with metal electrodes is then mounted on the electron transport layer, and the back side of the substrate with transparent electrodes is polished. This simple fabrication process solves the high cost problem caused by complex fabrication processes.

[0041] Building upon the first aspect, this invention also proposes a projection optical engine, the main technical solution of which includes: the projection optical engine comprising three Micro-QLED chips as described in the first aspect, wherein the quantum dot emitting layers of the three Micro-QLED chips are respectively a blue quantum dot emitting layer, a green quantum dot emitting layer, and a red quantum dot emitting layer; the projection optical engine further comprises: a color combining prism and a projection lens; the three Micro-QLED chips combine the light beams of their respective display areas into a single optical path through the color combining prism, and then project the display through the projection lens. This invention uses active-matrix Micro-QLEDs in the projection optical engine to replace LCD, LCoS, DMD, and Micro-LED, improving luminous efficiency and color purity, thereby increasing the flexibility of the projection optical engine and reducing its size and cost.

[0042] Example

[0043] Please see Figure 1 This invention provides a Micro-QLED chip for a projection optical engine. The Micro-QLED chip comprises, from bottom to top: a substrate 1 with a transparent electrode, a hole injection layer 2, a hole transport layer 3, a quantum dot light-emitting layer 4, an electron transport layer 5, and a TFT driving circuit board 6 with a metal electrode.

[0044] The quantum dot light-emitting layer 4 is composed of a quantum dot color conversion film. The pixel arrangement on the quantum dot color conversion film corresponds one-to-one with the driving array of the TFT driving circuit board 6. The quantum dot color conversion film is made of lead-free copper-based mixed halide perovskite quantum dot material.

[0045] In this embodiment, the hole injection layer 2 is 10nm thick, the hole transport layer 3 is 30nm thick, the electron transport layer 5 is 50nm thick, and the quantum dot light-emitting layer 4 is 30nm thick.

[0046] In a preferred embodiment, the substrate 1 may be made of glass, silicon wafer, metal, quartz, ITO-coated polyethylene terephthalate film (ITO-PET) flexible substrate, polyetherimide (PEI) flexible substrate, etc.

[0047] In a preferred embodiment, the quantum dot light-emitting layer 4 can be prepared by room temperature synthesis. The quantum dot color conversion film has a conversion wavelength of 450-780nm, a half-width at half-maximum of ≤40nm, and a film thickness of ≤100nm.

[0048] The Micro-QLED chip for projection optical engine provided in this embodiment emits light after electrons and holes recombine within the quantum dot light-emitting layer 4 under a certain voltage drive. This embodiment uses lead-free copper-based mixed halide perovskite quantum dots CsCu2I. xBr y Cl 1-x-y Quantum dot (QDs) are used as the material for the quantum dot emitting layer 4 of a QLED. By adjusting the ratio of x and y, red, green, and blue quantum dot emitting layers 4 can be prepared, thereby creating red, green, and blue Micro-QLED chips. Because this embodiment uses non-lead-copper-based mixed halide perovskite quantum dots as the material for the quantum dot emitting layer 4 of the QLED, the environmental pollution caused by the toxicity of traditional lead-based perovskite quantum dots can be avoided. Furthermore, the active light emission method improves the performance of the Micro-QLED chip.

[0049] Please see Figure 2 This invention also proposes a method for fabricating a Micro-QLED chip for a projection optical engine, comprising the following steps:

[0050] S1. Fabricating a transparent electrode on a substrate to form a substrate with a transparent electrode attached.

[0051] In a preferred embodiment, a solution of silver (Ag), gold (Au), or platinum (Pt) nanowires can be repeatedly spray-printed onto the substrate 1 to form a substrate 1 with a transparent electrode. Due to the coffee ring effect, these droplets form a metal ring with a diameter of approximately 150 nm and a width of less than 10 nm after drying. If enough droplets are printed, the silver, gold, and platinum rings will overlap, thereby forming a conductive coating on the plastic surface, creating a transparent conductive electrode. At this point, light can still pass smoothly through the center of the nanoring, with a light transmittance >70%. The drying temperature is 80-150 degrees Celsius, the time is 10-30 minutes, and the film thickness is 5-20 nm.

[0052] In another preferred embodiment, indium tin oxide (ITO) (In2O:Sn), fluorine-doped tin oxide (FTO) (SnO2:F), or aluminum-doped zinc oxide (AZO) (ZnO:Al) can be sputtered onto the substrate 1 to form a substrate 1 with a transparent electrode.

[0053] S2. Prepare a hole injection layer 2 on the substrate 1. Specifically, spin-coat a hole injection layer material doped with a polymer crosslinking agent onto the transparent electrode to form a hole injection layer 2, and sinter it in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius.

[0054] In a preferred embodiment, the crosslinking agent may be polyethylene glycol, polypropylene glycol, trimethylolpropane, trimethylolethane, etc.

[0055] S3. Prepare a hole transport layer 3 on the hole injection layer 2. Specifically, spin-coat the hole transport layer material onto the hole injection layer 2 to form the hole transport layer 3, and sinter it in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius.

[0056] S4. Prepare a quantum dot light-emitting layer 4 on the hole transport layer 3. Specifically, prepare a quantum dot solution with a concentration of 50-100 mg / mL, spin-coat it onto the hole transport layer 3 to form the quantum dot light-emitting layer 4, and sinter it in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius.

[0057] In a preferred embodiment, a quantum dot solution with a concentration of 50-100 mg / mL can be prepared by a room temperature synthesis method, specifically including the following steps:

[0058] S41. Dissolve one or more solids selected from 0.1-1.5 mmol cesium iodide (CsI), 0.1-1.5 mmol cuprous iodide (CuI), 0.1-1.5 mmol cesium bromide (CsBr), 0.1-1.5 mmol cuprous bromide (CuBr), 0.1-1.5 mmol cesium chloride (CsCl), and 0.1-1.5 mmol cuprous chloride (CuCl) in 1-10 mL of dimethyl sulfoxide (DMSO) solution and stir thoroughly to obtain a precursor solution.

[0059] S42. Rapidly add the antisolvent dropwise to the precursor solution under vigorous stirring.

[0060] In a preferred embodiment, the antisolvent can be one or more of toluene, ethyl acetate, methyl formate, chloroform, etc.

[0061] S43. Centrifuge the obtained solution at 3000-10000 rpm for 5-10 minutes, discard the supernatant, and redissolve the precipitate in 1-10 mL of dimethyl sulfoxide (DMSO) solution to obtain a quantum dot solution with a concentration of 50-100 mg / mL.

[0062] In practical applications, blue quantum dot solutions, green quantum dot solutions, or red quantum dot solutions can be prepared based on room temperature synthesis methods as needed.

[0063] S5. An electron transport layer 5 is prepared on the quantum dot light-emitting layer 4. Specifically, ZnO particles, TiO2 particles or ZnO:MgO particles are prepared into a solution of 50-100 mg / mL and spin-coated onto the quantum dot light-emitting layer to form the electron transport layer 5. The spin-coating rate is 1000-5000 rpm / min and the time is 30-40 seconds. The solution is then sintered in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius.

[0064] S6. Prepare a TFT driving circuit board 6 with metal electrodes, specifically by depositing a metal target onto the TFT driving circuit board to form a TFT driving circuit board 6 with metal electrodes.

[0065] In a preferred embodiment, the metal target material can be gold, silver, platinum, or aluminum.

[0066] S7. The TFT driving circuit board 6 with metal electrodes is mounted on the electron transport layer 5 and the back side of the substrate 1 with transparent electrodes is polished.

[0067] Polishing the back of the substrate can enhance the light output.

[0068] The method for fabricating a Micro-QLED chip for a projection optical engine provided in this embodiment has a simple fabrication process, solving the high cost problem caused by the complex process of the existing hot-injection synthesis method. Furthermore, it uses lead-free copper-based mixed halide perovskite quantum dots prepared by room temperature synthesis as the light-emitting layer material of the QLED, achieving coordinated red, green, and blue light emission while avoiding environmental pollution.

[0069] Please see Figure 3 This embodiment also proposes a projection optical engine, which includes three monochromatic Micro-QLED chips 7 as described above. The quantum dot emitting layers of the three Micro-QLED monochromatic chips 7 are blue quantum dot emitting layers, green quantum dot emitting layers, and red quantum dot emitting layers, respectively. The projection optical engine also includes a color combining prism 8 and a projection lens 9. The three Micro-QLED chips combine the light beams of their respective display areas into a single optical path through the color combining prism 7 and project the light onto the screen 10 through the projection lens 9. Obviously, because the projection optical engine uses self-emissive Micro-QLED chips, it completely eliminates the illumination optical path required when using passively emitting chips, thereby greatly simplifying the structure of the projection optical engine. Its size and weight are significantly lower than those of traditional projection optical engines.

[0070] In this embodiment, the three display areas formed by the three monochrome Micro-QLED chips 7 each have the same number and spacing of tri-color quantum dot (QD) pixels, and adjacent display areas can be folded at angles from 0 to 180°. The bending angle range between the three display areas formed by the three monochrome Micro-QLED chips 7 is α, and satisfies 0 ≤ α ≤ 90°; when α = 0°, the Micro-QLED chip is a flat screen; when α = 90°, the two adjacent display areas of the Micro-QLED chip are perpendicular to each other.

[0071] In this embodiment, the image arrays formed by each monochrome Micro-QLED chip 7 emit different colors. That is, a Micro-QLED pixel array emitting a certain color is prepared in each independent region, namely blue light, green light and red light. A color conversion scheme is adopted using quantum dots of different colors. That is, the quantum dots form an array of the same number and spacing. Under the TFT driving circuit, active light emission is adopted to directly emit different colored light, and the pixel arrangement on the quantum dot color conversion pixel film should correspond one-to-one with the TFT driving array arrangement.

[0072] The projection optical engine provided in this embodiment uses an active-matrix quantum dot light-emitting diode (Micro-QLED) device instead of a Micro-LED, achieving the goals of improving luminous efficiency, enhancing color purity, and reducing costs. The Micro-QLED chip in this embodiment has a turn-on voltage of 2-4V and a luminous intensity greater than 2000 cd / m². 2 .

[0073] In summary, the Micro-QLED chip and its fabrication method for projection optical engines provided in this embodiment address the inherent toxicity of traditional lead-based perovskite quantum dots and the complexity of the hot-injection synthesis method. By employing non-lead-based copper-based mixed halide perovskite quantum dots prepared using a room-temperature synthesis method as the light-emitting layer material for the QLED, this invention achieves coordinated red, green, and blue light emission while avoiding environmental pollution and resolving the high cost issue caused by complex fabrication processes. Furthermore, addressing the low light utilization efficiency of projection optical engines, this invention uses active-emitting Micro-QLEDs to replace passive-emitting LCDs, LCoS, DMDs, and expensive Micro-LEDs, improving luminous efficiency and color purity, thereby enhancing the flexibility of the projection optical engine and reducing its size and cost.

[0074] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications and substitutions can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for fabricating a Micro-QLED chip for a projection optical engine, characterized in that, The method includes: Step 1: Fabricate a transparent electrode on the substrate to form a substrate with a transparent electrode attached; Step 2: Spin-coat the hole injection layer material doped with polymer crosslinking agent onto the transparent electrode to form a hole injection layer, and sinter it in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius. Step 3: Spin-coat the hole transport layer material onto the hole injection layer to form a hole transport layer, and sinter it in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius. Step 4: Prepare a quantum dot solution with a concentration of 50-100 mg / mL, spin-coat it onto the hole transport layer to form a quantum dot light-emitting layer, and sinter it in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius. The preparation of a quantum dot solution with a concentration of 50-100 mg / mL specifically includes: Step 41: Dissolve one or more of the following solids (0.1-1.5 mmol cesium iodide, 0.1-1.5 mmol cuprous iodide, 0.1-1.5 mmol cesium bromide, 0.1-1.5 mmol cuprous bromide, 0.1-1.5 mmol cesium chloride, and 0.1-1.5 mmol cuprous chloride) in 1-10 mL of dimethyl sulfoxide solution and stir thoroughly to obtain a precursor solution; Step 42: Rapidly add the antisolvent dropwise to the precursor solution under vigorous stirring; Step 43: Centrifuge the obtained solution at 3000-10000 rpm for 5-10 minutes, discard the supernatant, and redissolve the precipitate in 1-10 mL of dimethyl sulfoxide solution to obtain a quantum dot solution with a concentration of 50-100 mg / mL. Step 5: Prepare a solution of ZnO particles, TiO2 particles or ZnO:MgO particles at a concentration of 50-100 mg / mL, and spin-coat it onto the quantum dot light-emitting layer to form an electron transport layer. The spin-coating rate is 1000-5000 rpm / min, the time is 30-40 seconds, and the layer is sintered in a nitrogen atmosphere for 10-30 minutes at a sintering temperature of 100-200 degrees Celsius. Step 6: Deposit the metal target onto the TFT driver circuit board to form a TFT driver circuit board with metal electrodes. Step 7: Mount the TFT driving circuit board with metal electrodes onto the electron transport layer and polish the back side of the substrate with transparent electrodes.

2. The method for fabricating a Micro-QLED chip for a projection optical engine as described in claim 1, characterized in that, Step 1, the fabrication of the transparent electrode on the substrate, specifically includes: A solution of gold, silver, or platinum nanowires is repeatedly sprayed and printed onto the substrate; or Indium tin oxide, fluorine-doped tin oxide, or aluminum-doped zinc oxide are prepared on the substrate by sputtering.

3. The method for fabricating a Micro-QLED chip for a projection optical engine as described in claim 1, characterized in that, The crosslinking agent is polyethylene glycol, polypropylene glycol, trimethylolpropane, or trimethylolpropane, and the metal target is gold, silver, platinum, or aluminum.

4. The method for fabricating a Micro-QLED chip for a projection optical engine as described in any one of claims 1 to 3, characterized in that, The quantum dot solution is a blue quantum dot solution, a green quantum dot solution, or a red quantum dot solution.

5. A Micro-QLED chip for a projection optical engine, characterized in that, The Micro-QLED chip, from bottom to top, includes: a substrate with transparent electrodes, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and a TFT driving circuit board with metal electrodes. The quantum dot light-emitting layer is composed of a quantum dot color conversion film. The pixel arrangement on the quantum dot color conversion film corresponds one-to-one with the driving array of the TFT driving circuit board. The quantum dot color conversion film is made of lead-free copper-based mixed halide perovskite quantum dot material.

6. The Micro-QLED chip for a projection optical engine as described in claim 5, characterized in that, The quantum dot color conversion film has a conversion wavelength of 450-780nm, a full width at half maximum (FWHM) of ≤40nm, and a film thickness of ≤100nm.

7. The Micro-QLED chip for a projection optical engine as described in claim 5, characterized in that, The substrate is a flexible substrate made of glass, silicon wafer, metal, quartz, ITO-coated polyethylene terephthalate film, or polyetherimide flexible substrate.

8. A projection optical engine, characterized in that, The projection optical engine includes three Micro-QLED chips as described in any one of claims 5 to 7, wherein the quantum dot light-emitting layers of the three Micro-QLED chips are a blue quantum dot light-emitting layer, a green quantum dot light-emitting layer, and a red quantum dot light-emitting layer, respectively; and the projection optical engine further includes a color combining prism and a projection lens. The three Micro-QLED chips combine the light beams from their respective display areas into a single optical path using a beam combining prism, and then project the image through a projection lens.

9. The projection optical engine as described in claim 8, characterized in that, The three Micro-QLED chips are fabricated using the method for fabricating Micro-QLED chips for projection optical engines as described in any one of claims 1 to 4.

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