Quantum dot light-emitting diode with controllable light-emitting wavelength and preparation method thereof

Abstract

The invention relates to a quantum dot light-emitting diode with controllable light-emitting wavelength and a preparation method thereof. The quantum dot light-emitting diode comprises a substrate, a bottom reflector, a metal conductive channel, a current expansion layer, a current limiting layer, a hole injection layer, a quantum dot light-emitting layer, an electron injection layer, a top reflector and a top electrode. The current limiting layer is provided with a plurality of opening areas, each area corresponds to an independent bottom / top reflector, an independent quantum dot light-emitting unit is formed, the light-emitting process is limited in a micro-cavity resonant cavity, specific wavelength light emitting is enhanced, stray light is restrained, the opening areas are projected in the projection range of the reflectors, the light utilization efficiency is improved, independent control can be achieved, and the light-emitting efficiency is improved. And diversified requirements are met. The bottom reflecting mirror is a conductive reflecting mirror, has high-efficiency reflecting and conductive performance, and improves the light extraction efficiency and the light emitting uniformity. The invention further provides a preparation method, the injection layer and the light-emitting layer are prepared by adopting methods such as spraying and spin coating, the technological process of the quantum dot light-emitting diode can be greatly simplified, and therefore the cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of light-emitting diodes, and in particular to a quantum dot light-emitting diode with controllable emission wavelength and a preparation method thereof. Background Art

[0002] Since the breakthrough in quantum dot synthesis technology in the 1980s, quantum dot light-emitting diodes (QLEDs), representing a new generation of display technology, have gradually moved from the laboratory prototype stage to a new era of commercial application. This leap not only marks a major advancement in materials science and electronic engineering, but also brings unprecedented color expression and energy efficiency improvements to display technology.

[0003] In 2008, the successful development of multicolor QLED devices, specifically the achievement of high-brightness red, orange, yellow, and green emission through precise size control of CdSe / ZnS core-shell quantum dots, marked a milestone in the widespread application of quantum dots in display technology. Quantum dots, with their unique quantum confinement effect, exhibit significant advantages such as narrowband emission, high luminous efficiency, and wide color gamut coverage, making them an ideal candidate for next-generation display technology.

[0004] However, as QLED technology continues to evolve, issues such as wide spectral linewidth and unstable emission wavelengths have become key constraints hindering its further development. These issues directly impact the color purity, contrast, and long-term reliability of QLED displays, limiting their potential for application in high-end display markets such as ultra-high-definition televisions, virtual reality (VR), and augmented reality (AR) devices. Despite significant investment in technological breakthroughs by both the scientific research community and industry, achieving high color purity, long-wavelength stability, and streamlining fabrication processes remain challenging.

[0005] Specifically, current research on QLED wavelength regulation and stability enhancement focuses on modifying the quantum dot material itself, such as through surface modification, alloying, or constructing complex core-shell structures, in order to improve luminescence properties. However, these methods often involve complex synthesis processes, making large-scale, low-cost production difficult. Furthermore, their effectiveness in improving the stability of the emission wavelength center is limited, making it difficult to meet the stringent requirements for high consistency and long-term stability for commercial applications.

[0006] Therefore, developing QLED technology with controllable emission wavelength, stable fabrication process, and high color purity has become a key scientific issue and technical bottleneck that needs to be addressed in this field. This requires not only a deeper understanding of the luminescence mechanism of quantum dot materials, but also innovative breakthroughs in material design, synthesis process, and device structure optimization to push QLED technology to a higher level and meet the higher requirements of future display technologies for color expression, energy efficiency, and reliability. Summary of the Invention

[0007] The purpose of this application is to provide a quantum dot light-emitting diode with controllable emission wavelength, which has the characteristics of high color purity and stable wavelength center of the light, and can achieve high-density integration and meet the display needs of different fields.

[0008] The purpose of the present application is achieved through the following technical solutions: the quantum dot light-emitting diode with controllable emission wavelength of the present application includes a substrate, a bottom reflector, a metal conductive channel, a first current spreading layer, a current limiting layer, a hole injection layer, a quantum dot light-emitting layer, an electron injection layer, a second current spreading layer, a top reflector and a top electrode; The bottom reflector is formed on the substrate, the first current spreading layer is formed on the bottom reflector, and the current limiting layer is located between the first current spreading layer and the electron injection layer; The current limiting layer includes a plurality of opening areas, each opening area having an independent corresponding bottom reflector and top reflector; Each layer between the bottom reflector and the top reflector corresponding to each opening area forms an independent quantum dot light-emitting diode unit, and the metal conductive channel is filled between the bottom reflectors.

[0009] In one embodiment, the bottom reflector or the top reflector comprises a filter layer.

[0010] In one embodiment, the projection of the opening area in the vertical direction is within the projection range of the corresponding bottom reflector and the top reflector in the vertical direction.

[0011] In one embodiment, each independent quantum dot light emitting diode includes an independent second current spreading layer.

[0012] In one embodiment, the bottom reflector is a conductive reflector.

[0013] In one embodiment, centers of the bottom reflector, the opening area, and the top reflector overlap in a horizontal plane.

[0014] The present application further provides a method for preparing a quantum dot light-emitting diode with controllable emission wavelength, which specifically includes: Forming various layers of the bottom reflector on the substrate by combining a photolithography process and an epitaxial growth method; Filling metal between the plurality of bottom reflectors to form a metal conductive channel; depositing a first current spreading layer; forming a current limiting layer on the first current spreading layer, wherein the current limiting layer includes a plurality of opening areas; forming a hole injection layer, a quantum dot light-emitting layer, and an electron injection layer in sequence; forming a second current spreading layer on the electron injection layer; forming a top reflector on the second current spreading layer; forming a top electrode on the second current spreading layer; The projection of the opening area in the vertical direction is within the projection range of the corresponding bottom reflector and the top reflector in the vertical direction, and each layer between the bottom reflector and the top reflector corresponding to each opening area forms an independent quantum dot light-emitting diode unit.

[0015] In one embodiment, the electron injection layer and the hole injection layer are formed by spraying or spin coating, and the quantum dot light-emitting layer is prepared by inkjet printing, photolithography or spin coating.

[0016] In one embodiment, after forming the metal conductive channel, a surface planarization step is further included.

[0017] Compared with the prior art, this application has the following beneficial effects: This application improves the color purity of the light by integrating a bottom reflector or a top reflector in a quantum dot light-emitting diode, combined with an independent quantum dot light-emitting layer, and cooperates with a filter layer to selectively reflect light of a specific wavelength, effectively suppressing stray light and ensuring the stability of the center of the light-emitting wavelength.

[0018] This application utilizes metal conductive channels between the bottom reflectors, combined with an opening in the current-confining layer, to achieve an array layout of independent quantum dot light-emitting diode units. Each unit's bottom reflector, top reflector, and intermediate layer form an independent optical and electrical structure, supporting pixel-level drive and suitable for high-resolution display applications. Furthermore, the modular design allows for rapid adaptation to different application requirements by adjusting the quantum dot combination and device integration process, shortening the product development cycle.

[0019] This application can achieve flexible control of the light output direction and preparation process through the bottom reflector or the top reflector. A conductive reflector is used as the bottom reflector, which can serve as an electrode and enhance light reflection. By optimizing the preparation process of the quantum dot light-emitting layer, the needs of the lighting field can be met. In addition, the narrow linewidth characteristics effectively solve the screen window effect of AR / VR equipment, and show great potential in cutting-edge fields such as medical endoscopic imaging and quantum sensing. The design of independent quantum dot light-emitting diode units allows for dynamic adjustment of the emission wavelength through the combination of quantum dots and the regulation of current injection. During the patterning process of the top reflector, the light extraction efficiency can be further optimized by adjusting the periodic structural parameters of the reflector, so that the external quantum efficiency (EQE) of the device is increased by more than 20% compared with the traditional structure.

[0020] The preparation method provided by this application is compatible with a variety of mature processes such as epitaxial growth, photolithography, spray coating, and spin coating, and supports large-scale mass production. The surface flatness step is further used to ensure the interface flatness of the multilayer structure. The collaborative design of the conductive reflector and the filter layer proposed in this application breaks through the limitation of the traditional reflector as only a light reflecting element, gives it an electrode function, and simplifies the device structure. At the same time, the overlapping design of the opening area and the projection range of the reflector ensures the vertical coupling of the light field, reduces light loss, and provides key technical support for the development of ultra-thin, foldable display devices. In summary, this application has achieved breakthroughs in the color purity, integration, application compatibility, etc. of quantum dot light-emitting diodes through improvements in materials, structures and processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of a quantum dot light-emitting diode with controllable emission wavelength in one embodiment of the present application; Figure 2 This is a schematic flow chart of a method for preparing a quantum dot light-emitting diode with controllable emission wavelength according to an embodiment of the present application; Figure 3 This is a structural diagram of a method for preparing a quantum dot light-emitting diode with controllable emission wavelength according to an embodiment of the present application; Figure 4 This is a schematic structural diagram of a quantum dot light-emitting diode with controllable single emission wavelength in one embodiment of the present application; Figure 5 This is a schematic structural diagram of a quantum dot light-emitting diode with controllable single emission wavelength in another embodiment of the present application.

[0022] Explanation of the accompanying drawings: 100, substrate; 200, bottom reflector; 300, metal conductive channel; 400, first current spreading layer; 500, current limiting layer; 610, hole injection layer; 620, quantum dot light-emitting layer; 630, electron injection layer; 700, second current spreading layer; 800, top reflector; 900, top electrode. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It will be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some, rather than all, structures related to the present application are shown in the accompanying drawings. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0024] As used herein, the terms "comprise," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0025] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0026] With the rapid development of display technology, quantum sensing, optoelectronic integration and other fields, new requirements have been put forward for the color purity, wavelength stability and integration density of light source devices. Traditional luminescent materials are limited by wide-spectrum emission and wavelength drift problems, and it is difficult to meet the needs of high-end display devices for wide color gamut and high contrast. At the same time, in precision applications such as quantum sensing and medical imaging, the precise control of the emission wavelength has become a key bottleneck restricting performance improvement. The core challenge of quantum dot light-emitting diodes is how to achieve precise and stable emission wavelength while maintaining high color purity, while taking into account the process feasibility of large-scale integration. Existing technologies mostly focus on the modification of quantum dot materials, but problems such as complex preparation process and insufficient wavelength stability still restrict its industrialization process. In response to the above problems, this application proposes a QLED design based on an independent unit array and a filtered reflective structure. The structural design and preparation process of the QLED will be elaborated in detail below. Please refer to Figure 1In a preferred embodiment of the present application, a quantum dot light-emitting diode with controllable emission wavelength includes a substrate 100, a bottom reflector 200, a metal conductive channel 300, a first current spreading layer 400, a current confinement layer 500, a hole injection layer 610, a quantum dot light-emitting layer 620, an electron injection layer 630, a second current spreading layer 700, a top reflector 800 and a top electrode 900, wherein the bottom reflector 200 is formed on the substrate 100, the first current spreading layer 400 is formed on the bottom reflector 200, the current confinement layer 500 is located between the first current spreading layer 400 and the electron injection layer 630, the current confinement layer 500 includes a plurality of opening areas, each opening area has an independently corresponding bottom reflector 200 and top reflector 800, wherein each layer between the bottom reflector 200 and the top reflector 800 corresponding to each opening area forms an independent quantum dot light-emitting diode unit, and the metal conductive channel 300 is filled between the bottom reflectors 200.

[0027] Specifically: the bottom reflector 200 is directly deposited on the surface of the substrate 100 and can serve as the basic reflective structure layer for forming an optical resonant cavity. The first current expansion layer 400 covers the bottom reflector 200 and is used to evenly disperse the driving current. The current limiting layer 500 is embedded between the first current expansion layer 400 and the electron injection layer 630. It is designed with multiple independent opening areas inside. Each opening area corresponds to a complete quantum dot light-emitting unit. The bottom and top of the opening area are respectively configured with independent bottom reflectors 200 and top reflectors 800. The two can work together to form a microcavity resonant structure. The metal conductive channel 300 fills the gap area of the bottom reflector 200 to form an electrical interconnection path between independent units.

[0028] By providing multiple opening regions in the current confinement layer 500, each region forms an independent quantum dot light-emitting unit and is equipped with independent bottom / top reflectors 800, the light-emitting process of each unit can be confined to the microcavity resonator, enhancing the luminous intensity of specific wavelengths through optical interference effects while suppressing stray light of non-target wavelengths. Experimental data shows that this structure can improve the luminous efficiency of the target wavelength by more than 40% and achieve ultra-narrowband emission with a full width at half maximum (FWHM) of ≤1nm. The metal conductive channel 300 fills the gap between the bottom reflector 200, avoiding crosstalk between adjacent units through physical isolation. Combined with the opening design of the current confinement layer 500, the device can achieve pixel density at the micron or even sub-micron level, meeting the integration requirements of applications such as Micro-LED displays and high-resolution optical communications.

[0029] The bottom / top reflector 800 combination in each opening area allows for independent adjustment of the emission wavelength. Compared to traditional QLEDs, this structure controls wavelength center drift to within ±2nm, improving spectral stability. It is particularly suitable for fields such as quantum sensing and medical imaging, which require precise wavelength matching. The integrated design of the bottom reflector 200 and the top reflector 800 is compatible with existing semiconductor processes and can use processes such as spin coating, facilitating large-scale production. The synergistic effect of the top reflector 800 and the bottom reflector 200 not only enhances microcavity resonance but also further optimizes light extraction efficiency through light extraction structures (such as surface roughening and photonic crystals). Combined with the high quantum yield of the quantum dot light-emitting layer 620, the overall external quantum efficiency of the device is higher.

[0030] The bottom reflector 200 or the top reflector 800 is integrated with a filter layer structure. The filter layer can achieve light transmission within a specific wavelength range through material selection and structural design. For example, the bottom reflector 200 can be a high-reflectivity metal reflector, a distributed Bragg reflector (DBR) with a reflectivity greater than 99%, or a high-contrast grating reflector, capable of reflecting light. The filter layer of the top reflector 800 can be designed as a composite structure of a distributed Bragg reflector (DBR) and a filter dielectric. Its periodically stacked dielectric materials (such as SiO2 / TiO2) create bandpass filtering characteristics, allowing only light of a target wavelength (such as 520nm) to pass through. The filter layer can be embedded with metal nanoparticles or photonic crystal structures, further enhancing the light extraction efficiency of the target wavelength and suppressing stray light through surface plasmon resonance or the photonic bandgap effect.

[0031] Specifically, the vertical projection of the opening area is within the corresponding vertical projection range of the bottom reflector 200 and the top reflector 800. When the vertical projection of the opening area is within the vertical projection range of the bottom reflector 200 and the top reflector 800, photons are prevented from being unable to be reflected by the reflectors due to exceeding the reflector projection range, thereby improving the utilization efficiency of photons, allowing more photons to be transmitted and utilized along the intended path, and improving the overall performance of the optical system. For example, in some optical instruments, such as telescopes and microscopes, the clarity and brightness of the image can be improved. The opening area serves as a channel for photons to enter and exit. Its projection is within the reflector projection range, which can prevent photons from leaking out of the reflector during the reflection process, reduce photon scattering and loss, and enable photons to propagate more accurately along the designed path. If the opening area exceeds the reflector range, some photons may not be effectively reflected by the reflector. When the projection of the opening area is completely covered by the projection of the reflector, the photon propagation path in the optical system is predictable and controllable.

[0032] Each independently configured quantum dot LED structure employs an independent second current spreading layer 700, enabling independent control of the light-emitting units corresponding to a single opening region. Specifically, the independent second current spreading layer 700 can regulate the current flowing into the light-emitting units in that opening region, thereby controlling the luminous intensity and other characteristics of the LEDs in that region, meeting diverse display and lighting requirements. The independent second current spreading layer 700 provides an independent current path for each quantum dot LED. This independent second current spreading layer 700 confines the current to a specific light-emitting unit, allowing the current magnitude and distribution to be precisely adjusted based on the unit's needs, thereby improving the overall luminous efficiency of the quantum dot LED and reducing energy consumption. In conventional structures, multiple light-emitting units share a current path. A current anomaly in one unit can affect the normal operation of other units. The independent second current spreading layer 700 isolates the current flow of each unit, preventing any impact on other units. This allows for independent control of the light emission of each opening region, enabling the creation of display screens with high resolution, high contrast, and rich colors, as well as lighting devices capable of dynamic lighting and intelligent dimming.

[0033] In the quantum dot light-emitting diode structure of this application, the bottom reflector 200 further utilizes a conductive reflector. This not only possesses the high-efficiency photon reflection properties of a conventional reflector, reflecting as many photons upward as possible to improve light extraction efficiency, but also exhibits excellent electrical conductivity, enabling it to function as part of an electrode, providing a stable current input to the quantum dot light-emitting layer 620 without the need for an additional electrode channel. While a conventional bottom reflector 200 may simply reflect photons, a conductive reflector, while maintaining this reflective performance, optimizes its materials and structure to reflect more photons back to the quantum dot light-emitting layer 620, ultimately emitting from the device's top surface. The conductive reflector can be constructed from a composite structure of a high-reflectivity metal (such as silver or aluminum) and a transparent conductive oxide (such as indium tin oxide (ITO)). As part of the electrode, the conductive reflector provides uniform current input to the quantum dot light-emitting layer 620. This good current distribution ensures uniform recombination and emission of electron-hole pairs within the quantum dots, reducing local overheating and current crowding, and improving the device's light uniformity and stability.

[0034] Please see further Figure 4 , Figure 4 The figure in the figure is a schematic diagram of the result of a single quantum dot light-emitting diode, wherein the bottom reflector can be a single-layer reflector, such as a silver reflector. In this specific embodiment, it is not necessary to make a separate metal conductive channel. At this time, the single-layer silver reflector serves as both a bottom reflector and a metal conductive channel.

[0035] Specifically, the centers of the bottom reflector, the opening area, and the top reflector 800 overlap in the horizontal plane. When the centers of the bottom reflector, the opening area, and the top reflector 800 overlap in the horizontal plane, the photons emitted by the quantum dot light-emitting layer 620 can be more effectively reflected back by the top reflector 800. Combined with the bottom reflector, after multiple round-trip reflections inside the device, the photon wavelength can be made more concentrated. When the centers of the key components overlap, the propagation path of the photons inside the device is more orderly, reducing the lateral scattering and leakage of the photons, so that more photons can be effectively guided to the emission direction. In addition, the overlapping design reduces the uneven stress and electric field distribution inside the device. The uniform electric field distribution also helps to reduce the occurrence of electrical failure phenomena such as electromigration, thereby improving the reliability and stability of the device. The overlapping design can adopt simpler process steps and more precise alignment technology in the device preparation process, reducing the preparation cost and difficulty, optimizing the optical mode of the device, reducing the loss and scattering of light inside the device, and controlling the propagation path of light in the quantum dot light-emitting layer 620 by adjusting the size and shape of the opening area.

[0036] In addition, by selecting the substrate, top reflector and other materials, a quantum dot light-emitting diode with light emitting from the bottom can be realized. Figure 5 The substrate material is GaN, sapphire or glass substrate, the bottom reflector is GaN / AlInN material, the top reflector reflects all photons, and the photons are emitted from the bottom reflector to form a quantum dot light-emitting diode with bottom light emission.

[0037] As can be seen, this application first proposes a QLED design based on an independent unit array and a filter-reflector structure. Through the coordinated design of a high-reflectivity bottom reflector, a top reflector 800 integrated filter layer, an opening in the current-confining layer 500, and independent conductive channels, a high-density integrated, wavelength-controllable QLED architecture is constructed. Through modular unit layout, filter-reflector coupling, and optimized process compatibility, this technology achieves breakthrough performance with over 30% improvement in color purity and a wavelength center drift ≤±2nm. It is also compatible with cross-dimensional applications such as flexible electronic skin and Micro-LED backlighting. It enables quantum dot light-emitting diodes with narrow linewidth and controllable wavelength center. These narrowband emission characteristics make QLEDs suitable for high-speed optical communications and precision bioimaging. Ultra-high-resolution QLEDs can eliminate the "screen door effect" of VR / AR devices and meet the high pixel density (10,000 PPI) requirements of the metaverse. QLED's high color purity and narrow emission spectrum enable it to cover a wider color gamut, further promoting the development of the display industry. Through multidisciplinary cross-disciplinary approaches (such as nanosynthesis, device engineering, and AI-driven design), QLED is expected to have a more profound impact in the fields of display, energy, and biotechnology.

[0038] See also Figure 2 、 Figure 3 The present application further provides a method for preparing a quantum dot light-emitting diode with controllable emission wavelength, specifically comprising: depositing various layers of a bottom reflector 200 on a substrate 100 by epitaxial growth, filling metal between the multiple bottom reflectors 200 to form a metal conductive channel 300, depositing a first current spreading layer 400, forming a current limiting layer 500 on the first current spreading layer 400, wherein the current limiting layer 500 includes multiple opening areas, sequentially forming a hole injection layer 610, a quantum dot light-emitting layer 620, and an electron injection layer 630, forming a second current spreading layer 700 on the electron injection layer 630, forming a top reflector 800 on the second current spreading layer 700, and forming a top electrode 900 on the second current spreading layer 700, wherein the vertical projection of the opening area is within the vertical projection range of the corresponding bottom reflector 200 and the top reflector 800, and the layers between the bottom reflector 200 and the top reflector 800 corresponding to each opening area form an independent quantum dot light-emitting diode unit.

[0039] In the specific preparation method, first, on a selected substrate 100 (such as glass, sapphire, copper, etc.), a photolithography process is used, and epitaxial growth techniques such as molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD) are adopted to sequentially deposit the various layers of the bottom reflector 200 according to specific material sequences and thickness requirements, thereby forming multiple independent bottom reflector 200 structures.

[0040] The gaps between the multiple bottom reflectors 200 are filled with metal materials (e.g., copper, gold, etc.) using methods such as physical vapor deposition (PVD), chemical vapor deposition (CVD), or electroplating to form metal conductive channels 300. These channels not only connect the individual bottom reflectors 200 but also effectively reduce the device's resistance and improve current transmission efficiency. After the bottom reflectors 200 are patterned and the metal conductive channels 300 are filled, a first current spreading layer 400 is deposited on the surface using deposition techniques such as sputtering and evaporation. The first current spreading layer 400 is typically made of a transparent conductive material, such as ITO, to achieve uniform current spreading and injection. A current confining layer 500 is formed on the first current spreading layer 400 using photolithography and etching techniques. The current confining layer 500 is composed of an insulating material (e.g., silicon carbide, silicon oxide, aluminum nitride, etc.) and contains multiple openings whose size, shape, and position are calculated to achieve current confinement and lateral light field confinement.

[0041] A hole injection layer 610, a quantum dot light-emitting layer 620, and an electron injection layer 630 are formed on the current confinement layer 500 using sequential processes (such as evaporation, inkjet printing, doctor blade coating, and spin coating). The quantum dot light-emitting layer 620 can be made of different materials and sizes as needed. A second current spreading layer 700 is formed on the electron injection layer 630 using masking, photolithography, and other fabrication processes, and a top reflector 800 is formed thereon. The vertical projections of the top reflector 800 and the bottom reflector 200 must precisely correspond. Specifically, the vertical projections of the opening areas must fall within the vertical projections of the corresponding bottom reflector 200 and top reflector 800, ensuring that each layer between the bottom reflector 200 and top reflector 800 corresponding to each opening area forms an independent quantum dot light-emitting diode unit.

[0042] By optimizing the design of the bottom reflector 200 and top reflector 800, light extraction efficiency can be improved. The formation of the current confinement layer 500 reduces current leakage and light loss, improving luminous efficiency and stability. During the QLED fabrication process, precise control of the material and thickness of the filter layer in the top reflector enables precise control of the emission wavelength. Simultaneously, optimizing the design and fabrication process of each functional layer reduces interlayer interference and stress concentration, thereby improving device reliability and stability.

[0043] Specifically, the electron injection layer 630 and the hole injection layer 610 are formed by spraying or spin coating, and the quantum dot light-emitting layer 620 is prepared by inkjet printing or spin coating. The electron injection layer 630 and the hole injection layer 610 are prepared by spraying or spin coating. In the spraying method, the electron injection material (such as zinc oxide ZnO, molybdenum oxide MoO x A hole injection material (e.g., poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) PEDOT:PSS) is dissolved in a suitable solvent to form a uniform solution. The solution is then sprayed evenly onto the pre-treated surface of the substrate 100 in a mist form using a spray gun. Drying and annealing are performed under appropriate temperature and atmospheric conditions to evaporate the solvent, allowing the material to form a uniform, dense electron injection layer 630 or hole injection layer 610 on the substrate 100. Spin coating involves securing the substrate 100 on a spin coater and dropping the solution onto the center of the substrate 100. The centrifugal force generated by the high-speed rotation of the substrate 100 spreads the solution evenly across the surface. Drying and annealing are also performed to obtain the desired injection layer.

[0044] The quantum dot light-emitting layer 620 is prepared using inkjet printing, photolithography, or spin coating. In the inkjet printing method, a quantum dot solution (e.g., a quantum dot material such as cadmium sulfide (CdS) or cadmium selenide (CdSe) dispersed in a solvent to form an ink) is loaded into an inkjet printer cartridge. The ink is then printed onto the hole injection layer 610 using a nozzle according to a predetermined pattern and position, forming a quantum dot light-emitting layer 620 with a specific pattern. In the photolithography method, a layer of photoresist is first coated on the hole injection layer 610. A mask is then used to expose and develop the desired pattern, resulting in a quantum dot light-emitting layer 620 with a specific pattern. The spin coating method, similar to the spin coating method used to prepare the electron injection layer 630 and the hole injection layer 610, involves spin coating the quantum dot solution onto the substrate 100. By controlling parameters such as the spin speed and time, a uniform quantum dot film is obtained. Subsequently, drying and other processes are performed to form the quantum dot light-emitting layer 620. Spraying or spin coating is preferably used to form the quantum dot light-emitting layer 620.

[0045] The electron injection layer 630 and the hole injection layer 610 are formed by spraying or spin coating. Compared with traditional high vacuum deposition methods (such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), the spraying method has low equipment requirements and simple operation. The spraying method does not require a complex vacuum environment and only requires simple spraying equipment and a drying annealing device. The spin coating method only requires a spin coater and basic drying equipment, which can greatly simplify the process flow, reduce equipment investment and operating costs, and make large-scale preparation of QLED devices more feasible and economical. It can fully utilize materials and reduce material waste. During the spraying and spin coating process, the amount of solution and the coating range can be precisely controlled to reduce material waste.

[0046] The quantum dot light-emitting layer 620 is prepared by inkjet printing, photolithography, or spin coating, which can precisely control the position and volume of ink droplets and achieve high-resolution patterning. Photolithography can produce fine and complex patterns, and spin coating is suitable for uniform coating over large areas. By selecting the appropriate method according to the needs, a quantum dot light-emitting layer 620 that meets the requirements can be prepared. These methods can be flexibly adjusted according to different quantum dot materials and device structure requirements. For example, for quantum dots of different sizes and compositions, the optimal light-emitting performance can be achieved by adjusting the parameters of spraying, spin coating, or printing. At the same time, these methods are highly compatible with existing semiconductor manufacturing processes, facilitating multifunctional integration and large-scale production. Overall, the preparation method of the present application reduces complex equipment requirements and operating steps, improves production efficiency, reduces equipment investment, material waste, and energy consumption, making QLED preparation more economical.

[0047] In the fabrication process of electronic devices such as quantum dot light-emitting diodes (QLEDs), after successfully forming metal conductive pathways (e.g., electrodes or interconnects made of metal materials such as gold (Au), silver (Ag), and copper (Cu)) through deposition, photolithography, and etching, a surface planarization step is required to ensure uniform and stable deposition of subsequent functional layers (e.g., electron transport layer, quantum dot light-emitting layer, hole transport layer, etc.). This surface planarization process typically utilizes chemical mechanical polishing (CMP). First, the substrate, after forming the metal conductive pathways, is secured to the worktable of the CMP equipment. A polishing slurry containing an abrasive (such as aluminum oxide or silicon dioxide) and chemical additives is evenly applied to the substrate surface. The CMP equipment is then activated, with the polishing head in contact with the substrate surface at a specific pressure and speed. The rotating polishing pad drives the polishing slurry, mechanically abrading and chemically etching the substrate surface. The mechanical abrasion gradually removes surface protrusions. Simultaneously, the chemical additives react with the surface material, promoting its dissolution and removal, thereby achieving surface planarization. Using chemical mechanical polishing (CMP) technology for surface flattening can improve the quality of subsequent layer deposition. After flattening, the roughness and undulation of the metal conductive channel surface are reduced, allowing the subsequently deposited functional layers such as the electron transport layer and quantum dot light-emitting layer to be deposited evenly and flatly on the metal conductive channel surface, avoiding problems such as film cracking and uneven thickness caused by surface unevenness, and improving the performance and stability of the functional layer. Specific embodiments Some specific implementation methods will be further introduced below to further explain the technical solution of this application in detail.

[0049] First, a bottom reflector structure is deposited and fabricated on the substrate surface. Substrate materials include, but are not limited to, metals (e.g., copper), semiconductors (e.g., silicon, gallium nitride, GaN, gallium arsenide, GaAs), and insulators (e.g., glass, sapphire). Bottom reflector types include, but are not limited to, distributed Bragg reflectors (DBRs), dielectric film DBRs (e.g., TiO2 / SiO2, HfO2 / SiO2), nitride DBRs (e.g., AlInN / GaN), arsenide DBRs, grating structures, air-gap DBRs (e.g., air / GaN), photonic crystal structures, and metal reflectors (e.g., Ag, Al). Mirror parameters are determined according to design principles. Design criteria include: non-metallic reflectors must have a reflectivity greater than 99.0%, reflector parameters are determined by the characteristics of the light-emitting layer (central wavelength, reflectivity), and different reflector types must be matched to specific device structures. Parameters include: film thickness related to the central wavelength of the light-emitting layer, the number of periods that influence the reflection bandwidth, and the duty cycle that optimizes structural symmetry.

[0050] Advanced process technologies such as photolithography and magnetron sputtering are used to achieve precise deposition of metal conductive channels in the device structure. The selected material systems include but are not limited to: single metal gold (Au) and composite metal layer structures such as chromium (Cr) / Au, nickel (Ni) / Au, etc. The conductive performance and adhesion strength can be optimized through the combination of multiple metal layers. On this basis, a transparent conductive film is further prepared on the surface of the device as a current spreading layer. The material system of this layer includes transparent conductive oxide materials such as indium tin oxide (ITO), indium-doped zinc oxide (IZO), aluminum-doped zinc oxide (AZO) and fluorine-doped tin oxide (FTO). By matching the material properties, efficient current spreading and optical transmittance are achieved. Subsequently, based on micro-nano processing technologies such as photolithography and masking, thin film deposition processes such as thermal evaporation and magnetron sputtering are used to prepare a current confinement layer with a patterned structure. This functional layer material system encompasses insulating dielectric materials such as silicon dioxide (SiO2) and aluminum oxide (Al2O3), as well as wide-bandgap semiconductor materials such as silicon carbide (SiC) and aluminum nitride (AlN). Precise current spatial confinement is achieved through matching material properties. During the manufacturing process, mask design and photolithography pattern transfer techniques are combined to achieve nanometer-level precision current channel control, effectively improving device current uniformity and photoelectric conversion efficiency.

[0051] Hole injection layer (HTL): uses inkjet printing, spin coating or doctor blade coating to deposit material systems with excellent hole transport properties, including: metal oxide systems (such as zinc magnesium oxide ZnMgO, zinc oxide ZnO and its ligand-modified materials), organic small molecule systems (such as tris (4-carbazolyl-9-phenyl) amine TCTA), quantum dot light-emitting layer (QD-EML): prepared by solution coating process (inkjet / spin coating / doctor blade coating), material systems include: II-VI group quantum dots These include: Group I-III-VI quantum dots (e.g., CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS), Group III-VI quantum dots (e.g., CuInS, CuInSeS, AgInS, AgInSeS), Group III-V quantum dots (e.g., InP), alloy quantum dots (e.g., Cd-based, In-based, and Zn-based alloys), and perovskite quantum dots. This layer features size tunability (core-shell size 1-20nm), achieving full spectral coverage from 400-2000nm through quantum confinement. Electron injection layer (ETL): Composite electron transport systems are prepared using spin coating, doctor blade coating, or inkjet processes, including organic / inorganic composites (e.g., PEDOT:PSS / TFB, PEDOT:PSS / PF8Cz) and metal oxide composites (e.g., ZnO / ZnMgO).

[0052] Transparent conductive oxide thin films are deposited using photolithography and mask techniques combined with thermal evaporation / magnetron sputtering. Materials include indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), and fluorine tin oxide (FTO). This layer achieves uniform current spreading through its high transmittance and low resistivity. The filter top reflector (FTM) is fabricated using thermal evaporation / magnetron sputtering, based on mask design and photolithographic pattern transfer technology. Reflector types include distributed Bragg reflectors (DBRs), grating structures, and photonic crystals. The material system consists of a combination of high-refractive-index materials (TiO2) and low-refractive-index materials (SiO2). The TiO2 / SiO2 dielectric film DBR utilizes a three-film stack structure, achieving specific wavelength filtering through controllable layer thickness and periodicity. Magnetron sputtering technology is used to deposit a composite metal layer on the sample surface as a metal top electrode (MTE). The material system includes: elemental metals (Al, Ag, Au), composite metal layers (Cr / Au), and other metal combinations. Efficient charge injection is achieved through high conductivity and low contact resistance characteristics.

[0053] As can be seen from the foregoing, the present application provides a quantum dot light-emitting diode with high color purity and controllable emission wavelength. Its structure includes a supporting substrate (transparent conductive gallium nitride (GaN) / gallium arsenide (GaAs), conductive non-transparent copper / silicon (Si), non-conductive transparent glass / sapphire, etc.), a high-reflectivity bottom reflector prepared on the substrate, a metal conductive channel, a transparent conductive film, a dielectric film current limiting layer, a hole injection layer (ETL), a quantum dot layer (QDs), an electron injection layer (HTL), a transparent conductive film, a filter top reflector, and a top electrode. Among them, the bottom reflector and the top reflector constitute an optical resonant cavity, and the reflector is composed of a dielectric film DBR, a nitride DBR, an arsenide DBR, a grating, an air gap DBR, a photonic crystal, a metal reflector, etc. Quantum dots cover a wide range of luminescent materials, including but not limited to CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, CuInS, CuInSeS, AgInS, AgInSeS, InP, CuZnSe, ZnMnSe, PbS, PbSe, Cd alloys, In alloys, Zn alloys, or perovskite materials. The core-shell size can be adjusted depending on the material and luminescent wavelength. Metal electrodes include but are not limited to Al, Ag, Au, and metal combinations such as Cr / Au and Cr / Al / Cr. A transparent conductive film serves as a current spreading layer, and materials include but are not limited to indium tin oxide (ITO), indium-doped zinc oxide (IZO), aluminum-doped zinc oxide (AZO), and fluorine-doped tin oxide (FTO). The current confining layer includes but is not limited to SiO2 / AlN / SiC, which increases the hole injection current density and balances the electron and hole injection efficiencies. The device can emit light from the front or bottom. When the light is emitted from the front, taking the dielectric film DBR as an example, a patterned high-reflectivity DBR is deposited on the substrate, and then a metal electrode is deposited in the aisle using the patterning as the bottom conductive channel and heat dissipation channel. Combined with the top filter DBR of different structures, a quantum dot light-emitting diode with narrow linewidth and controllable wavelength center is formed. Among them, the bottom reflector can be replaced by a conductive reflector to simplify the process and achieve the same effect of quantum dot light-emitting diode; the device structure of the bottom light is based on a transparent substrate, such as GaN, sapphire, glass and other substrates. Its top reflector is a high-reflectivity reflector, and the bottom reflector is a filter reflector. It can be composed of a variety of different types of reflectors. When nitride DBR, air gap DBR, GaN grating, and arsenide DBR are used as filter reflectors, there is no need to prepare an additional bottom electrode. The substrate or reflector is directly used as the injection channel of the bottom electrode. Combined with the high-reflectivity top reflector, a quantum dot light-emitting diode with high color purity and controllable emission wavelength is prepared. The prepared high-performance device achieves a linewidth of less than 1 nm and a divergence angle of less than 40°; This application combines filter reflectors with different manufacturing processes to produce quantum dot light-emitting diodes with high color purity and stable wavelength center for both front and bottom emission. This structure can be used to prepare devices with different light emission directions depending on the substrate. A high-reflectivity bottom reflector can be prepared on a high-thermal-conductivity and high-conductivity substrate, a current-expanding layer and a conductive channel can be prepared thereon, and a current-limiting layer, a hole-injection layer, a quantum dot layer, an electron-injection layer, a transparent conductive film, a top reflector, and a top electrode can be prepared thereon in sequence. By adjusting the film thickness, duty cycle, and other conditions of the reflector in combination with the emission wavelength of the quantum dot layer, a quantum dot light-emitting diode with high color purity and a stable wavelength center emitting from the front can be obtained. A conductive reflector can be prepared on a conductive substrate as a conductive channel, and other thin films can be spin-coated in sequence, and then combined with a top filter reflector, to obtain a quantum dot light-emitting diode with a simpler process, vertical injection, and high color purity and a stable wavelength center emitting from the front. A conductive filter reflector can be prepared on a transparent conductive substrate, and other thin layers can be spin-coated thereon, and combined with a top reflector with high reflectivity, to obtain a quantum dot light-emitting diode with high color purity and a stable wavelength center emitting from the bottom.

[0054] The above is only a specific implementation of the present application. Any other improvements made based on the concept of the present application are considered to be within the scope of protection of the present application.

Claims

1. A quantum dot light-emitting diode with controllable emission wavelength, characterized in that: It includes a substrate, a bottom reflector, a metal conductive channel, a first current spreading layer, a current limiting layer, a hole injection layer, a quantum dot light-emitting layer, an electron injection layer, a second current spreading layer, a top reflector and a top electrode; The bottom reflector is formed on the substrate, the first current spreading layer is formed on the bottom reflector, and the current limiting layer is located between the first current spreading layer and the electron injection layer; The current limiting layer includes a plurality of opening areas, each opening area having an independent corresponding bottom reflector and top reflector; Each layer between the bottom reflector and the top reflector corresponding to each opening area forms an independent quantum dot light-emitting diode unit, and the metal conductive channel is filled between the bottom reflectors.

2. The quantum dot light-emitting diode with controllable emission wavelength according to claim 1, characterized in that: The bottom mirror or the top mirror includes a filter layer.

3. The quantum dot light-emitting diode with controllable emission wavelength according to claim 1, characterized in that: The projection of the opening area in the vertical direction is within the projection range of the corresponding bottom reflector and the top reflector in the vertical direction.

4. The quantum dot light-emitting diode with controllable emission wavelength according to claim 1, characterized in that: Each independent quantum dot light emitting diode includes an independent second current spreading layer.

5. The quantum dot light-emitting diode with controllable emission wavelength according to claim 1, characterized in that: The bottom reflector is a conductive reflector.

6. The quantum dot light-emitting diode with controllable emission wavelength according to claim 1, characterized in that: Centers of the bottom reflector, the opening area, and the top reflector overlap in a horizontal plane.

7. A method for preparing a quantum dot light-emitting diode with controllable emission wavelength, characterized in that: include: Forming various layers of the bottom reflector on the substrate by combining a photolithography process and an epitaxial growth method; Filling metal between the plurality of bottom reflectors to form a metal conductive channel; depositing a first current spreading layer; forming a current limiting layer on the first current spreading layer, wherein the current limiting layer includes a plurality of opening areas; forming a hole injection layer, a quantum dot light-emitting layer, and an electron injection layer in sequence; forming a second current spreading layer on the electron injection layer; forming a top reflector on the second current spreading layer; forming a top electrode on the second current spreading layer; The projection of the opening area in the vertical direction is within the projection range of the corresponding bottom reflector and the top reflector in the vertical direction, and each layer between the bottom reflector and the top reflector corresponding to each opening area forms an independent quantum dot light-emitting diode unit.

8. The method for preparing a quantum dot light-emitting diode with controllable emission wavelength according to claim 7, characterized in that: The electron injection layer and the hole injection layer are formed by spraying or spin coating, and the quantum dot light-emitting layer is prepared by inkjet printing, photolithography or spin coating.

9. The method for preparing a quantum dot light-emitting diode with controllable emission wavelength according to claim 7, characterized in that: After forming the metal conductive channel, a step of planarizing the surface is also included.

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