High resolution quantum dot pixelated light emitting thin film and method of making the same

Abstract

This invention relates to a high-resolution quantum dot pixelated luminescent thin film and its preparation method, belonging to the field of quantum dot technology. The method includes: spin-coating photoresist onto a substrate; drying the substrate; exposing the substrate using photolithography equipment; applying a developer to a predetermined position on the substrate to obtain a photoresist pattern layer; depositing an insulating layer on the photoresist pattern layer using silane; removing the photoresist pattern from the insulating layer; spin-coating a PEI solution onto the insulating layer to obtain a PEI layer; and dropping a QD solution onto the PEI layer to deposit a QD layer. This invention utilizes the hydrophobicity of silane to achieve dewetting for quantum dot pixelation, and the hydrophobicity of the insulating layer to allow the PEI solution to spontaneously deposit at the photoresist pattern positions. Furthermore, based on the electrostatic interaction between the QD solution and the PEI solution, the QD solution is adsorbed into the PEI solution, resulting in a high-resolution quantum dot pixelated luminescent thin film, improving film quality and passivating surface defects in the QD layer.

Description

Technical Field

[0001] This invention relates to the field of quantum dot technology, and in particular to a high-resolution quantum dot pixelated light-emitting thin film and its preparation method, as well as a transparent quantum dot light-emitting diode and its preparation method. Background Technology

[0002] Resolution is a crucial parameter that enables displays to vividly present images. With the advent of head-mounted electronic devices for virtual reality (VR), augmented reality (AR), and mixed reality (MR), the demand for bright, high-resolution electroluminescent (EL) devices has become urgent. One such technology is AR, a subtle fusion of virtual information and the real world. It not only effectively reflects the content of the real world but also facilitates the display of virtual information in a subtle, superimposed manner. In visual AR, users need prompts based on the head-mounted display to allow the real world to overlap with computer graphics, after which they can fully see the surrounding real world. Therefore, near-eye displays with high-resolution pixels and the ability to present transparency are crucial for realizing augmented reality and artificial intelligence. Due to inherent limitations in cost and materials, liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs) face significant obstacles in achieving high resolution for near-eye displays. Quantum dots (QDs), with their narrow half-width and wide color gamut, are considered promising contenders for future luminescent reality materials. Pixelation is a crucial step in incorporating these technologies into display, anti-counterfeiting, and optical chip applications. Furthermore, red (R), green (G), and blue (B) micron / submicron pixels fabricated using QDs offer the advantage of providing bright, vivid, and immersive content images without visual discomfort at near-eye viewing distances, making them a significant frontier in the display field.

[0003] Currently, methods for patterning quantum dot (QD) luminescent films mainly include nanoimprint lithography, inkjet printing, and photolithography. However, the use of nanoimprint lithography for pattern transfer and alignment still faces technical obstacles, with insufficient scalability and maturity for large-scale production, limiting the technology to laboratory-scale demonstrations. Inkjet printing is a widely studied and promising method capable of fabricating patterned QD luminescent films with normal light-emitting structures. However, issues related to resolution and thickness uniformity persist due to unstable drying kinetics. In recent years, with the development of semiconductor technology and the development and application of national photolithography equipment, photolithography technology has become a research hotspot in the field of high-resolution displays due to its advantages in large-scale, rapid fabrication of QD patterns, attracting significant attention from research institutions both domestically and internationally. With the development of quantum dot patterning technology using photolithography, research shows that photolithography has significant advantages in achieving ultra-high resolution QDs, such as the ability to form micron to submicron scale patterns on large areas of the desired substrate, the ability to simultaneously define patterns on large areas of the panel, and the ability to prepare ultraviolet-irradiated patterns solely through optical diffraction at the edges of the pattern mask, thus providing extremely high pattern quality. It is worth noting that quantum dots (QDs) are composed of a finite number of atoms, possess high surface energy, and exhibit chemical, optical, or thermal instabilities. Therefore, the structural degradation and optical instability of QDs are major challenges for integrating them into high-resolution display and imaging sensor system arrays. QDs require solution processing, while the organic light-emitting diodes (OLEDs) used in OLEDs can be patterned through thermal evaporation. Traditional photolithography uses a photoresist layer, a photolithographic polymer layer, as a mask layer applied to the quantum dot film, followed by depatching via development. However, the solution processing used for photolithography deposition and development damages the underlying QD layer. Furthermore, obtaining a full-color RGB image requires at least three photolithography processes, inevitably damaging the already patterned QD layer. Damaged patterns affect the device's light-emitting performance and may even hinder the complete rendering of the displayed image. Therefore, patterning with traditional photoresist can destructively damage QDs.

[0004] In summary, existing methods for fabricating patterned quantum dot light-emitting thin films require the use of solutions for photolithography deposition and development on the QDs layer, which can damage the QDs layer, affect the light-emitting performance of the device, and result in the incomplete display of the pattern. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problem that the existing method for preparing patterned quantum dot light-emitting thin films requires the use of solutions for photolithography deposition and development on the QDs layer, which will damage the QDs layer.

[0006] To address the aforementioned technical problems, this invention provides a method for preparing a high-resolution quantum dot pixelated light-emitting thin film, comprising: Photoresist is spin-coated onto the substrate surface; The substrate with photoresist spin-coated is dried; The dried substrate is exposed using photolithography equipment; The developer is applied to a predetermined position on the substrate surface and developed to obtain a photoresist pattern layer; A PFTS insulating layer is deposited on the surface of the photoresist pattern layer using silane self-assembly technology; Remove the photoresist pattern from the PFTS insulating layer to obtain a PFTS insulating layer with a mesh pattern; The PEI solution is spin-coated onto the surface of the PFTS insulating layer with the mesh pattern to obtain the PEI layer; A QD solution is dropped onto the surface of the PEI layer to deposit a QD layer, thereby obtaining a high-resolution quantum dot pixelated light-emitting film.

[0007] In one embodiment of the present invention, the step of spin-coating the photoresist onto the substrate surface further includes: Clean the substrate with acetone and isoacetone in sequence; Place the cleaned substrate on a heating table to dry.

[0008] In one embodiment of the present invention, after dropping the QD solution onto the surface of the PEI layer to deposit the QD layer and obtain a high-resolution quantum dot pixelated light-emitting film, the method further includes using an energy dispersive spectroscopy spectrometer in a scanning electron microscope to detect the elemental distribution on the surface of the high-resolution quantum dot pixelated light-emitting film.

[0009] In one embodiment of the present invention, the substrate is a transparent conductive thin-film glass or a silicon wafer.

[0010] In one embodiment of the present invention, the shape of the photoresist pattern is circular, square, or hexagonal.

[0011] In one embodiment of the present invention, the PEI solution is an aqueous PEI solution.

[0012] The present invention also provides a high-resolution quantum dot pixelated light-emitting film, wherein the high-resolution quantum dot pixelated light-emitting film is prepared by the above-described high-resolution quantum dot pixelated light-emitting film preparation method.

[0013] This invention also provides a method for fabricating a transparent quantum dot light-emitting diode, comprising: Provides a PFTS insulating layer with a mesh pattern prepared using the above-described high-resolution quantum dot pixelated light-emitting thin film preparation method; A colloidal-doped oxide semiconductor solution is spin-coated onto the surface of the PFTS insulating layer with a mesh pattern to obtain an electron transport layer; The PEI solution was spin-coated onto the surface of the electron transport layer to obtain the PEI layer; QD solution is dropped onto the surface of the PEI layer to deposit the QD layer; A chlorobenzene solution was spin-coated onto the surface of the QD layer to obtain a hole transport layer; A Kapton tape with a preset pattern is placed as a mask at a first preset position on the surface of the hole transport layer, and silver nanowires are coated on the surface of the mask to obtain a cathode. A Kapton tape with a preset pattern is placed as a mask at a second preset position on the surface of the hole transport layer, and indium tin oxide is applied to the surface of the mask to obtain the anode.

[0014] In one embodiment of the present invention, the PEI solution is a PEI ethanol solution.

[0015] The present invention also provides a transparent quantum dot light-emitting diode, wherein the transparent quantum dot light-emitting diode is prepared by the above-described transparent quantum dot light-emitting diode preparation method.

[0016] The high-resolution quantum dot pixelated luminescent film preparation method provided by this invention includes: spin-coating photoresist onto a substrate surface and drying and exposing the substrate; applying a developer to a predetermined position on the substrate surface to obtain a photoresist pattern layer; depositing a PFTS insulating layer on the surface of the photoresist pattern layer using silane self-assembly technology; removing the photoresist pattern from the PFTS insulating layer; spin-coating a PEI solution onto the surface of the PFTS insulating layer to obtain a PEI layer; and finally, dropping a QD solution onto the surface of the PEI layer to deposit a QD layer. This invention utilizes the hydrophobicity of silane to achieve dewetting, thereby realizing quantum dot pixelation, and utilizes the hydrophobicity of PFTS to allow the PEI solution to spontaneously deposit at the photoresist pattern position. Finally, based on the electrostatic interaction between the QD solution and the PEI solution, the QD solution spontaneously adsorbs into the PEI solution, obtaining a high-resolution quantum dot pixelated luminescent film. This avoids direct photolithography on the QDs layer, preventing damage to the QDs layer, improving the film quality of the QDs layer, and passivating surface defects in the QDs layer. Attached Figure Description

[0017] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 This is a flowchart of the high-resolution quantum dot pixelated light-emitting thin film preparation method provided by the present invention; Figure 2This is a schematic diagram of the high-resolution quantum dot pixelated light-emitting thin film preparation process provided by the present invention; Figure 3 (a) in the figure is a schematic diagram of a verification result provided by the present invention; Figure 3 (b) in the diagram is a schematic diagram of the second type of verification result provided by the present invention; Figure 3 (c) in the figure is a schematic diagram of the third verification result provided by the present invention; Figure 3 (d) in the figure is a schematic diagram of the fourth verification result provided by the present invention; Figure 4 This is a fluorescence microscope image of a high-resolution quantum dot pixelated luminescent thin film provided by the present invention; Figure 5 (a) is a fluorescence microscope image of the second type of high-resolution quantum dot pixelated luminescent film provided by the present invention; Figure 5 (b) is a fluorescence microscope image of the third type of high-resolution quantum dot pixelated luminescent film provided by the present invention; Figure 6 This is a flowchart of a transparent quantum dot light-emitting diode fabrication method provided by the present invention. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0019] Example 1: Reference Figure 1 The diagram shows a flowchart of the high-resolution quantum dot pixelated light-emitting thin film preparation method provided by the invention, including: S10: Spin-coat the photoresist onto the substrate surface.

[0020] Alternatively, the substrate may be a transparent conductive thin-film glass or a silicon wafer.

[0021] In some embodiments, before step S10, the substrate is cleaned with acetone and isoacetone in sequence; the cleaned substrate is then placed on a heating table for drying.

[0022] For example, the substrate can be cleaned sequentially with acetone or isopropanol, and then placed on a heating stage at 110°C. o Dry at C for 10 minutes to prevent moisture on the substrate from affecting the subsequent spin-coating of photoresist. After the substrate has dried and cooled, apply photoresist AZ5214 to the entire substrate and spin-coat at 3500 rpm for 40 seconds.

[0023] In other embodiments, other temperatures and times may be set when drying the substrate to prevent the influence of moisture on the substrate surface on the photoresist; alternatively, other photoresists may be applied to the substrate surface, which is not limited in this application.

[0024] S20: Dry the substrate with photoresist spin-coated.

[0025] In some embodiments, step S20 is specifically implemented as follows: the substrate is placed at 105 o Dry at C for 5 minutes to increase the interaction between the photoresist and the substrate and prevent the photoresist from peeling off during the subsequent development process.

[0026] In other embodiments, other temperatures and times may be set when drying the substrate, which is not limited in this application.

[0027] S30: Expose the dried substrate using photolithography equipment.

[0028] In this embodiment, the lithography equipment used is ARM / 6 / 350 / NUV / DCCD / BSV / M,USA. Other models of lithography equipment may be used in other embodiments, and this application does not limit them.

[0029] S40: Apply the developer to a predetermined position on the substrate surface and develop to obtain a photoresist pattern layer, such as... Figure 2 As shown in (a) of the diagram.

[0030] Optionally, the pattern shape on the photoresist pattern layer can be circular, square, hexagonal, etc.

[0031] In this embodiment, the developer used is AZ400K. In other embodiments, other developers may be used, and this application does not limit them.

[0032] S50: A perfluorooctyltrichlorosilane (PFTS) insulating layer is deposited on the surface of the photoresist pattern layer using silane self-assembly technology, such as... Figure 2 As shown in (b) of the diagram.

[0033] Alternatively, the silane can be a fluorosilane or other hydrophobic functional silane. This is because the hydrophobicity of the silane allows for dewetting, thus enabling QD pixelation, and it can also be used as an insulating layer in subsequent PEI solution and photoresist patterning processes.

[0034] S60: Remove the photoresist pattern from the PFTS insulating layer to obtain a PFTS insulating layer with a mesh pattern, such as... Figure 2 As shown in (c) in the figure.

[0035] S70: A polyethylenimine (PEI) solution is spin-coated onto the surface of a PFTS insulating layer with a mesh pattern to obtain a PEI layer.

[0036] After the PEI solution is spin-coated onto the surface of the PFTS insulating layer, due to the hydrophobicity of PFTS, the PEI solution will spontaneously deposit into the hydrophilic regions, i.e., the initial photoresist pattern areas, such as... Figure 2 As shown in (d) in the figure.

[0037] Specifically, the PEI solution in this embodiment is an aqueous PEI solution.

[0038] S80: A quantum dot (QD) solution is dropped onto the surface of a PEI layer to deposit a QD layer, thereby obtaining a high-resolution quantum dot pixelated light-emitting film.

[0039] Due to the electrostatic interaction between the QD solution and the PEI solution, the QD solution will spontaneously adsorb into the PEI solution, i.e., the initial photoresist pattern area, such as... Figure 2 As shown in (e), a high-resolution quantum dot pixelated light-emitting film is finally obtained, as shown in Figure (e). Figure 2 As shown in (f) in the figure.

[0040] The high-resolution quantum dot pixelated light-emitting thin film fabrication method provided in this embodiment uses a hydrophobic silane deposition insulating layer to form a dewetting layer, and utilizes the electrostatic interaction between the PEI solution and the QD solution to form an electroadsorption layer. Due to the difference in their surface free energies, the QDs undergo dehumidification and are selectively deposited to construct patterns. This method eliminates the need for photolithography on the QDs layer, avoiding damage to the QDs layer caused by the deposition and development solutions used in this process, improving the film quality of the QDs layer, and passivating surface defects in the QDs layer.

[0041] To verify the above scheme, this embodiment, after obtaining the high-resolution quantum dot pixelated luminescent film, also used the energy-dispersive spectroscopy (EDS) instrument built into a scanning electron microscope (SEM) to detect the elemental distribution on the surface of the final high-resolution quantum dot pixelated luminescent film. The detection results are as follows: like Figure 3 As shown in (a) and (b), the N element signal is mainly concentrated in the initial photoresist pattern area, and there is almost no N element signal in other areas. It can be seen that the hydrophobicity of the PEI solution based on the PFTS insulating layer is mainly concentrated in the initial photoresist pattern area to form an electroadsorption layer.

[0042] like Figure 3As shown in (c) and (d), the Si element signal is in the outer region of the initial photoresist pattern, and the distribution of the F element signal indicates that the PFTS insulating layer is mainly distributed in the outer region of the photoresist pattern, forming a dewetting layer.

[0043] The staggered mesh arrangement of the dewetting layer and the electroadsorption layer can promote the adsorption of QD solution in the desired area to obtain a high-resolution quantum dot pixelated light-emitting film, thereby achieving the goal of pixelation.

[0044] For example, based on the above embodiments and detection results, this application also provides three types of high-resolution quantum dot pixelated light-emitting films prepared using this method, such as... Figure 4 The image shown is of line width 5 provided in this embodiment. High-resolution quantum dot pixelated light-emitting thin films with line patterns, such as Figure 5 Image (a) shows a high-resolution quantum dot pixelated light-emitting film with a rectangular pattern and a resolution of 1104 PPI provided in this embodiment. Figure 5 (b) shows a high-resolution quantum dot pixelated light-emitting film with a square pattern and a resolution of 2522 PPI provided in this embodiment.

[0045] In addition, in other embodiments, a minimum size of 5 was also manufactured based on the above-described preparation method. 5 The QD pattern of zinc sphalerite (CdSe) has a resolution exceeding 2522 PPI.

[0046] Based on the above embodiment 1, this application also provides a high-resolution quantum dot pixelated light-emitting film, which is obtained by the above-described high-resolution quantum dot pixelated light-emitting film preparation method.

[0047] Example 2: Based on Embodiment 1 above, this application also provides a method for fabricating a transparent quantum dot light-emitting diode, such as... Figure 6 The diagram shows a flowchart of a transparent quantum dot light-emitting diode fabrication method, including: S200: Provides a PFTS insulating layer with a mesh pattern prepared using the preparation method of Example 1 above.

[0048] S210: A colloidal doped oxide semiconductor solution is spin-coated onto the surface of a PFTS insulating layer with a mesh pattern to obtain an electron transport layer.

[0049] In this embodiment, step S210 is specifically implemented as follows: a colloidal doped oxide semiconductor solution is spin-coated onto the surface of a PFTS insulating layer with a mesh pattern at a speed of 2000 rpm for 40 seconds to obtain an electron transport layer, and the substrate is placed at 100°C. o Anneal on a hot plate for 20 minutes.

[0050] For example, in this embodiment, the colloidal doped oxide semiconductor solution is a colloidal Mg-doped ZnO nanocrystal solution. Optionally, in other embodiments, other solutions may also be used, and this application does not limit them.

[0051] S220: Spin-coating the PEI solution onto the surface of the electron transport layer to obtain the PEI layer.

[0052] Specifically, the PEI solution in this embodiment is a PEI ethanol solution.

[0053] Alternatively, in other embodiments, the PEI solution concentration can be adjusted as needed to obtain PEI layers of different thicknesses.

[0054] S230: Drop the QD solution onto the surface of the PEI layer to deposit the QD layer.

[0055] In this embodiment, step S230 is specifically implemented as follows: a QD solution is dropped onto the surface of the PEI layer to deposit the QD layer, and the substrate is heated to 60°C. o Dry at C for several minutes to dry the QD layer.

[0056] S240: Spin-coating a chlorobenzene solution onto the surface of the QD layer to obtain a hole transport layer.

[0057] In this embodiment, step S260 is specifically implemented as follows: a chlorobenzene solution with a concentration of 8 mg / ml is spin-coated onto the surface of the QD layer at a speed of 2000 rpm for 40 seconds to obtain a hole transport layer, and the substrate is then placed at 120°C. o Annealing at C for 15 minutes yields the light-emitting layer for a transparent quantum dot light-emitting diode.

[0058] S250: Place a Kapton tape with a preset pattern as a mask on the first preset position on the surface of the hole transport layer, and coat silver nanowires (AgNWs) on the surface of the mask to obtain a cathode.

[0059] Specifically, in this embodiment, the silver nanowires are prepared using an isopropanol solution with a concentration of 8 mg / ml.

[0060] Optionally, the preset patterns on the Kapton tape can be laser-engraved as needed.

[0061] S260: Place a Kapton tape with a preset pattern as a mask on the second preset position on the surface of the hole transport layer, and apply indium tin oxide (ITO) to the surface of the mask to obtain the anode.

[0062] The transparent electrode made of ITO and AgNWs in this embodiment has both high conductivity and high visible light transmittance, which can improve the transmittance of the transparent quantum dot light-emitting diode.

[0063] Based on the above embodiments, this application also provides a transparent quantum dot light-emitting diode, which is obtained by the above-described transparent quantum dot light-emitting diode fabrication method.

[0064] In this embodiment, the effective area of ​​a single transparent quantum dot light-emitting diode is defined as 1 mm² using the intersection of the anode and cathode. 1mm, to facilitate detection and measurement.

[0065] The transparent quantum dot light-emitting diode (LED) provided in this embodiment utilizes a PEI layer to precisely adjust the high-precision QD pattern, while the PFTS insulating layer acts as a barrier layer, suppressing the huge leakage current between the charge carrier transport layers. This improves the performance of the transparent quantum dot LED. Furthermore, transparent quantum dot LEDs fabricated using this method have resolutions ranging from 1104 PPI to 3031 PPI, with efficiencies as high as 15.6%, and their size can be significantly reduced to produce higher-density LED pixel arrays. In addition, this transparent quantum dot LED has a transmittance of up to 90.7%, exhibiting both high efficiency and high transmittance, and is expected to be used in augmented reality display technology and automotive head-up display devices in the future.

[0066] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a high-resolution quantum dot pixelated light-emitting thin film, characterized in that, include: Photoresist is spin-coated onto the substrate surface; The substrate with photoresist spin-coated is dried; The dried substrate is exposed using photolithography equipment; The developer is applied to a predetermined position on the substrate surface and developed to obtain a photoresist pattern layer; A PFTS insulating layer is deposited on the surface of the photoresist pattern layer using silane self-assembly technology; Remove the photoresist pattern from the PFTS insulating layer to obtain a PFTS insulating layer with a mesh pattern; The PEI solution is spin-coated onto the surface of the PFTS insulating layer with the mesh pattern to obtain the PEI layer; A QD solution is dropped onto the surface of the PEI layer to deposit a QD layer, thereby obtaining a high-resolution quantum dot pixelated light-emitting film.

2. The method for preparing a high-resolution quantum dot pixelated light-emitting thin film according to claim 1, characterized in that, Before spin-coating the photoresist onto the substrate surface, the following steps are also included: Clean the substrate with acetone and isoacetone in sequence; Place the cleaned substrate on a heating table to dry.

3. The method for preparing a high-resolution quantum dot pixelated light-emitting thin film according to claim 1, characterized in that, The step of dropping the QD solution onto the surface of the PEI layer to deposit the QD layer and obtain a high-resolution quantum dot pixelated luminescent film further includes using an energy-dispersive spectroscopy spectrometer in a scanning electron microscope to detect the elemental distribution on the surface of the high-resolution quantum dot pixelated luminescent film.

4. The method for preparing a high-resolution quantum dot pixelated light-emitting thin film according to claim 1, characterized in that, The substrate is a transparent conductive thin-film glass or silicon wafer.

5. The method for preparing a high-resolution quantum dot pixelated light-emitting thin film according to claim 1, characterized in that, The shape of the photoresist pattern is circular, square, or hexagonal.

6. The method for preparing a high-resolution quantum dot pixelated light-emitting thin film according to claim 1, characterized in that, The PEI solution is an aqueous solution of PEI.

7. A high-resolution quantum dot pixelated light-emitting thin film, characterized in that, The high-resolution quantum dot pixelated light-emitting film is prepared by the high-resolution quantum dot pixelated light-emitting film preparation method according to any one of claims 1-6.

8. A method for fabricating a transparent quantum dot light-emitting diode, characterized in that, include: Provides a PFTS insulating layer with a mesh pattern prepared using the high-resolution quantum dot pixelated light-emitting thin film preparation method according to any one of claims 1-6; A colloidal-doped oxide semiconductor solution is spin-coated onto the surface of the PFTS insulating layer with a mesh pattern to obtain an electron transport layer; The PEI solution was spin-coated onto the surface of the electron transport layer to obtain the PEI layer; QD solution is dropped onto the surface of the PEI layer to deposit the QD layer; A chlorobenzene solution was spin-coated onto the surface of the QD layer to obtain a hole transport layer; A Kapton tape with a preset pattern is placed as a mask at a first preset position on the surface of the hole transport layer, and silver nanowires are coated on the surface of the mask to obtain a cathode. A Kapton tape with a preset pattern is placed as a mask at a second preset position on the surface of the hole transport layer, and indium tin oxide is applied to the surface of the mask to obtain the anode.

9. The method for fabricating a transparent quantum dot light-emitting diode according to claim 8, characterized in that, The PEI solution is a PEI ethanol solution.

10. A transparent quantum dot light-emitting diode, characterized in that, The transparent quantum dot light-emitting diode is prepared by the transparent quantum dot light-emitting diode preparation method described in claim 8.

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