Capillary self-assembly high-resolution quantum dot light-emitting device based on sacrifice layer and nano-imprinting and preparation method thereof
By employing a capillary self-assembly process based on sacrificial layers and nanoimprinting, non-destructive, high-precision, and high-resolution quantum dot pixel patterning was achieved. This solves the damage and cross-contamination problems in the quantum dot transfer process of existing technologies, improves the resolution and contrast of the device, and is suitable for full-color displays.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUZHOU UNIV
- Filing Date
- 2026-04-10
- Publication Date
- 2026-07-10
AI Technical Summary
Existing technologies struggle to achieve non-destructive, high-precision, and high-resolution quantum dot pixel patterning, especially since cross-contamination and damage can easily occur during the transfer of quantum dots from the donor substrate to the acceptor substrate, affecting device efficiency.
Employing a capillary self-assembly process based on sacrificial layers and nanoimprinting, this method achieves photolithography-free, non-contact, and high-fidelity patterning of quantum dot pixels through stamp preforming, capillary self-assembly, and sacrificial layer-assisted transfer. The pixel pattern is defined using micro-nano imprinting, and the transfer is completed by selectively dissolving the sacrificial layer.
It achieves high-resolution and high-precision quantum dot pixel patterning, maintains the luminescent properties of quantum dots, avoids the use of harmful substances such as photoresist, improves the contrast of the device, and makes it suitable for full-color displays.
Smart Images
Figure CN122373608A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of optoelectronic device manufacturing technology, and in particular to a high-resolution quantum dot light-emitting device based on capillary self-assembly using a sacrificial layer and nanoimprinting, and its fabrication method. Background Technology
[0002] Quantum dot light-emitting diodes (QLEDs) are considered a core candidate for next-generation display technology due to their advantages such as high color purity, wide color gamut, and solution-processability. The key to achieving high-resolution QLED displays lies in fabricating a quantum dot pixel array that is tiny in size, precisely arranged, and has high fidelity.
[0003] Currently, the mainstream quantum dot patterning technologies mainly include inkjet printing and photolithography. Inkjet printing technology is limited by the coffee ring effect, nozzle clogging, and positioning accuracy, making it difficult to achieve high uniformity and high resolution (typically >50 PPI) pixel arrays. Although traditional photolithography technology offers high precision, the photoresist, developer, and etching processes it uses can easily cause irreversible chemical damage to the luminescent properties of quantum dots, leading to a decrease in device efficiency. In addition, photolithography processes are complex and costly.
[0004] In recent years, transfer printing technology has been introduced into microdisplay manufacturing. However, how to transfer nanomaterials, especially quantum dots that are sensitive to surfaces and the environment, from the donor substrate to the acceptor substrate with high fidelity and precision, while avoiding cross-contamination and damage, remains a significant challenge. Existing transfer printing technologies often have shortcomings in terms of transfer rate, pixel integrity, or resolution.
[0005] Therefore, there is an urgent need to develop a new method that can achieve non-destructive, high-precision, and high-resolution quantum dot pixel patterning to promote the application of QLED in fields such as micro-displays and augmented reality. Summary of the Invention
[0006] In view of this, the purpose of this invention is to provide a high-resolution quantum dot light-emitting device based on a sacrificial layer and nanoimprinting, and a method for its fabrication. This method achieves photolithography-free, non-contact, and high-fidelity patterning of quantum dot pixels through an ingenious process route of "stamp preforming - capillary self-assembly - sacrificial layer assisted transfer".
[0007] To achieve the above objectives, the present invention adopts the following technical solution: a high-resolution quantum dot light-emitting device based on a sacrificial layer and nanoimprinting, comprising, from bottom to top: a substrate with an etched indium tin oxide electrode pattern, a hole injection layer, a hole transport layer, a charge blocking layer, a quantum dot light-emitting pixel array, an electron transport layer, and an upper electrode.
[0008] This invention also provides a method for fabricating a high-resolution quantum dot light-emitting device based on a sacrificial layer and nanoimprinting, comprising the following steps: Step S1: Provide a substrate with an indium tin oxide electrode, and sequentially fabricate a hole injection layer and a hole transport layer on the substrate to form the device substrate; Step S2: Provide a smooth polydimethylsiloxane soft stamp, and spin-coat a sacrificial layer and a charge blocking layer sequentially on its surface; Step S3: Provide a silicon template with a cylindrical array on its surface, and press it onto the charge blocking layer to press through the charge blocking layer to form a honeycomb-shaped through-hole array. The upper part of the silicon pillars is pressed into a sacrificial layer, and the bottom of the through-hole exposes the sacrificial layer below. Step S4: Spin-coat the surface of the structure obtained in step S3 with quantum dot solution, and use capillary action to make the quantum dots self-assemble and fill the honeycomb-shaped through holes to form a periodically arranged array of quantum dot light-emitting pixels; Step S5: Flip the PDMS stamp carrying the quantum dot pixel array obtained in step S4 so that its quantum dot pixel surface is aligned and in contact with the hole transport layer surface of the device substrate obtained in step S1, and perform hot pressing transfer. Step S6: Remove the PDMS stamp to transfer the charge blocking layer, sacrificial layer, and quantum dot pixel array onto the hole transport layer; Step S7: Soak the structure obtained in step S6 in a solvent to selectively dissolve and completely remove the sacrificial layer, leaving only the honeycomb charge barrier layer and the quantum dot pixel array embedded in its pores; Step S8: On the surface of the structure obtained in step S7, an electron transport layer and an upper electrode are sequentially prepared to complete the fabrication of the quantum dot light-emitting diode device.
[0009] In a preferred embodiment, in step S1, the hole injection layer material is poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid), and the hole transport layer material is poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4′-(N-(4-sec-butylphenyl))diphenylamine)].
[0010] In a preferred embodiment, in step S2, the sacrificial layer comprises PVB, PS, or PMMA material; the charge blocking layer comprises PVA, PE, PS, or PCL.
[0011] In a preferred embodiment, in step S3, the period of the cylindrical array of the silicon template is 1-10 μm, the cylinder diameter is 50%-90% of the period value; the imprinting pressure is 0.1-1 MPa, the imprinting temperature is 80-130℃, and the imprinting time is 1-5 minutes.
[0012] In a preferred embodiment, the quantum dots in step S4 include core-shell quantum dots of cadmium selenide, indium phosphide, and zinc selenide.
[0013] In a preferred embodiment, in step S5, the pressure of the hot pressing transfer is 0.5-2 MPa, the temperature is 80-120°C, and the time is 2-10 minutes.
[0014] In a preferred embodiment, in step S7, the solvent selectively dissolves and completely removes the sacrificial layer without damaging the honeycomb charge barrier layer and the quantum dot pixel array embedded in its pores.
[0015] In a preferred embodiment, in step S8, the electron transport layer comprises zinc oxide, tin oxide, or zinc-magnesium oxide nanoparticles; the upper electrode comprises silver or aluminum.
[0016] Compared with the prior art, the present invention has the following beneficial effects: High resolution and high precision: Utilizing micro-nano imprinting to define pixel patterns, resolution can reach micrometer or even sub-micrometer levels, far exceeding inkjet printing. Non-destructive quantum dot design: The entire process avoids the use of photoresists, ultraviolet light, and high-energy plasmas that are harmful to quantum dots, maximizing the preservation of the quantum dot's luminescent properties.
[0017] Good pixel isolation: The formed PVA honeycomb insulating barrier can effectively isolate adjacent pixels, improve device contrast and prevent leakage.
[0018] Strong process compatibility: The method is compatible with solution-based processes, the process is relatively simplified, and it is suitable for large-area, batch manufacturing.
[0019] Suitable for full-color displays: Red, green, and blue pixels can be prepared in stages or in parallel by changing quantum dot solutions with different emission wavelengths, thus achieving full-color display. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the process flow for the preparation method of the present invention.
[0021] Figure 2 This is a demonstration of the final high-resolution luminous pattern effect. Detailed Implementation
[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0023] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0024] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.
[0025] A high-resolution quantum dot light-emitting device based on capillary self-assembly using a sacrificial layer and nanoimprinting, reference Figure 1-2 This is a composite structure of a "sacrificial layer-barrier layer" pre-constructed on a soft stamp. The preparation method is as follows: First, PVB is spin-coated onto a PDMS soft stamp as a sacrificial layer and transfer substrate, then PVA is spin-coated as a charge-barrier layer. A honeycomb-shaped array of through-holes (with PVB at the bottom of the holes) is imprinted onto the PVA layer using a hard silicon template. Capillary forces are then used to precisely fill each micropore with quantum dot solution, forming a self-assembled quantum dot pixel.
[0026] During the transfer stage, a PDMS stamp with a regular quantum dot pixel array is flipped over and hot-pressed onto an ITO substrate with a pre-prepared hole functional layer. Hot pressing ensures good contact between the quantum dots and the hole transport layer, while the PVB layer exhibits some adhesion at a certain temperature, aiding in adhesion and transfer. The PDMS stamp is then removed, and the PVB / PVA / quantum dot composite structure is completely transferred onto the substrate.
[0027] The most crucial step is sacrificial layer removal: by immersing the PVB layer in a selective solvent (such as ethanol), the PVB layer is completely dissolved, while the PVA layer and quantum dots remain unaffected. Ultimately, what remains on the substrate are individual quantum dot pixel "islands" physically isolated by PVA insulating barriers. This honeycomb-like PVA structure not only precisely defines the pixel position and shape, preventing charge and optical crosstalk between adjacent pixels, but also acts as a "dam" during subsequent solution processing of the electron transport layer, preventing material wetting that could lead to pixel color mixing.
[0028] The method for fabricating red high-resolution QLED devices is as follows: 1. Substrate Fabrication: A glass substrate with pre-etched strip-shaped ITO electrodes is provided. The substrate is ultrasonically cleaned sequentially with detergent, deionized water, acetone, and isopropanol, and then dried with nitrogen. A PEDOT:PSS aqueous solution is spin-coated at 4000 rpm for 40 seconds, followed by annealing at 150°C for 20 minutes to form a hole injection layer approximately 40 nm thick. Then, a chlorobenzene solution of TFB (concentration 8 mg / mL) is spin-coated at 3000 rpm for 40 seconds and annealed at 150°C for 20 minutes to form a hole transport layer approximately 30 nm thick.
[0029] 2. Seal preforming and quantum dot self-assembly: Take a PDMS stamp with a smooth surface. Spin-coat the surface with PVB solution at 2000 rpm for 30 seconds, then dry at 70°C.
[0030] PVA solution was spin-coated onto the PVB layer at 3000 rpm for 40 seconds, and then dried at 90°C.
[0031] 3. Prepare a silicon template with a cylindrical array (cylindrical period 5 μm, diameter 3 μm, height 1 μm). Align the silicon template with a PDMS stamp covered with PVB / PVA, apply a pressure of 0.5 MPa, and imprint at 80°C for 3 minutes. The PVA layer is perforated to form regular through-holes, while the bottom PVB layer remains intact.
[0032] 4. Remove the silicon template to obtain a structure with a honeycomb PVA through-hole array.
[0033] An octane solution of CdSe / ZnS core-shell structured red quantum dots was prepared. This solution was spin-coated onto the surface of the structure at 2000 rpm for 30 seconds. Utilizing capillary action, the quantum dot solution rapidly filled the PVA pores, forming a dense quantum dot film after solvent evaporation, with virtually no residue remaining on the top of the PVA insulating layer.
[0034] 5. Thermal transfer and sacrificial layer removal: Flip the PDMS stamp (with quantum dot pixel array) to align the quantum dot pixel surface with the prepared TFB layer surface. Hot press at 100℃ and 1 MPa pressure for 5 minutes.
[0035] After cooling, the PDMS stamp is slowly and uniformly peeled off. At this point, the PVB / PVA / quantum dot composite structure has been completely transferred onto the TFB layer of the ITO substrate.
[0036] Immerse the entire substrate in anhydrous ethanol and let it stand for 5 minutes. The PVB layer is completely dissolved, while the PVA layer, being insoluble in ethanol, retains its honeycomb structure. The quantum dot pixels are firmly confined within the PVA pores and adhere to the TFB layer. Remove the substrate and dry it with nitrogen gas.
[0037] 6. Fabrication of the upper functional layer and electrodes: A butanol solution of ZnO nanocrystals was spin-coated onto the obtained structure at 2500 rpm for 40 seconds, followed by annealing at 100°C for 10 minutes to form an electron transport layer approximately 30 nm thick. The PVA gate effectively prevented the flow of the ZnO precursor solution between pixels.
[0038] The substrate is placed in a vacuum evaporation chamber at a pressure below 5 × 10⁻ ...�. 4 At Pa, a silver (Ag) layer of approximately 100 nm thickness is deposited as the top electrode, and the electrode pattern is defined by a mask.
[0039] 7. Encapsulation: In a nitrogen glove box, the cover glass is bonded to the device substrate with UV-curing adhesive and then UV-cured to complete the device encapsulation.
[0040] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Those skilled in the art can make modifications or equivalent substitutions to the foregoing embodiments without departing from the spirit and scope of the present invention, and such modifications or equivalent substitutions should all be covered within the protection scope of the claims of the present invention.
Claims
1. A high-resolution quantum dot light-emitting device based on capillary self-assembly using a sacrificial layer and nanoimprinting, characterized in that, From bottom to top, it includes: a substrate with an etched indium tin oxide electrode pattern, a hole injection layer, a hole transport layer, a charge blocking layer, a quantum dot light-emitting pixel array, an electron transport layer, and a top electrode.
2. A method for fabricating a high-resolution quantum dot light-emitting device based on capillary self-assembly using a sacrificial layer and nanoimprinting, characterized in that, The fabrication of the high-resolution quantum dot light-emitting device based on capillary self-assembly using a sacrificial layer and nanoimprinting as described in claim 1 includes the following steps: Step S1: Provide a substrate with an indium tin oxide electrode, and sequentially fabricate a hole injection layer and a hole transport layer on the substrate to form the device substrate; Step S2: Provide a smooth polydimethylsiloxane soft stamp, and spin-coat a sacrificial layer and a charge blocking layer sequentially on its surface; Step S3: Provide a silicon template with a cylindrical array on its surface, and press it onto the charge blocking layer to press through the charge blocking layer to form a honeycomb-shaped through-hole array. The upper part of the silicon pillars is pressed into a sacrificial layer, and the bottom of the through-hole exposes the sacrificial layer below. Step S4: Spin-coat the surface of the structure obtained in step S3 with quantum dot solution, and use capillary action to make the quantum dots self-assemble and fill the honeycomb-shaped through holes to form a periodically arranged array of quantum dot light-emitting pixels; Step S5: Flip the PDMS stamp carrying the quantum dot pixel array obtained in step S4 so that its quantum dot pixel surface is aligned and in contact with the hole transport layer surface of the device substrate obtained in step S1, and perform hot pressing transfer. Step S6: Remove the PDMS stamp to transfer the charge blocking layer, sacrificial layer, and quantum dot pixel array onto the hole transport layer; Step S7: Soak the structure obtained in step S6 in a solvent to selectively dissolve and completely remove the sacrificial layer, leaving only the honeycomb charge barrier layer and the quantum dot pixel array embedded in its pores; Step S8: On the surface of the structure obtained in step S7, an electron transport layer and an upper electrode are sequentially prepared to complete the preparation of the quantum dot light-emitting diode device.
3. The method for fabricating a high-resolution quantum dot light-emitting device based on capillary self-assembly using a sacrificial layer and nanoimprinting, as described in claim 2, is characterized in that... In step S1, the hole injection layer material is poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid), and the hole transport layer material is poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4′-(N-(4-sec-butylphenyl))diphenylamine)].
4. The method for fabricating a high-resolution quantum dot light-emitting device based on a sacrificial layer and nanoimprinting capillary self-assembly according to claim 2, characterized in that, In step S2, the sacrificial layer includes PVB, PS, or PMMA materials; the charge blocking layer includes PVA, PE, PS, or PCL.
5. The method for fabricating a high-resolution quantum dot light-emitting device based on a sacrificial layer and nanoimprinting capillary self-assembly according to claim 2, characterized in that, In step S3, the period of the cylindrical array of the silicon template is 1-10 μm, the diameter of the cylinder is 50%-90% of the period value; the imprinting pressure is 0.1-1 MPa, the imprinting temperature is 80-130℃, and the imprinting time is 1-5 minutes.
6. The method for fabricating a high-resolution quantum dot light-emitting device based on capillary self-assembly using a sacrificial layer and nanoimprinting according to claim 2, characterized in that, In step S4, the quantum dots include core-shell quantum dots of cadmium selenide, indium phosphide, and zinc selenide.
7. The method for fabricating a high-resolution quantum dot light-emitting device based on a sacrificial layer and nanoimprinting capillary self-assembly according to claim 2, characterized in that, In step S5, the pressure of the hot pressing transfer is 0.5-2 MPa, the temperature is 80-120℃, and the time is 2-10 minutes.
8. The method for fabricating a high-resolution quantum dot light-emitting device based on capillary self-assembly using a sacrificial layer and nanoimprinting according to claim 2, characterized in that, In step S7, the solvent selectively dissolves and completely removes the sacrificial layer without damaging the honeycomb charge barrier layer and the quantum dot pixel array embedded in its pores.
9. The method for fabricating a high-resolution quantum dot light-emitting device based on a sacrificial layer and nanoimprinting capillary self-assembly according to claim 2, characterized in that, In step S8, the electron transport layer comprises zinc oxide, tin oxide, or zinc-magnesium oxide nanoparticles; the upper electrode comprises silver or aluminum.