A monolithic integrated structure of a hybrid Micro-LED and QLED full-color display device and its fabrication method

Abstract

This invention proposes a monolithic integrated structure and fabrication method for a hybrid Micro-LED and QLED full-color display device. Blue μLEDs and a bank are epitaxially grown and etched on the same epitaxial substrate, with red and green QLEDs located inside the bank. The red and green QLED structure, from bottom to top, consists of an anode, a hole injection layer, a hole transport layer, a quantum dot emitting layer, an electron transport layer, and a cathode. The blue μLEDs and red and green QLEDs are horizontally distributed on the substrate, with the cathode of the blue μLED connected to the anode of the red and green QLEDs, and vice versa. Red and green QLED pixels are fabricated on the structured blue Micro-LED substrate using inkjet printing technology, integrating a hybrid Micro-LED (PM) full-color display device. This technology avoids the technical challenges of mass transfer, simplifies the fabrication process, and enables high-efficiency display of RGB colors, providing a novel full-color technology solution for the display field.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic technology and information display technology, and particularly relates to a monolithic integrated structure of a Micro-LED and QLED hybrid full-color display device and its fabrication method. Background Technology

[0002] Micro-light-emitting diodes (Micro-LEDs, μLEDs) are hailed as a next-generation display technology due to their superior performance in brightness, lifespan, resolution, and efficiency. They are considered a dynamic new display technology following TFT-LCD and OLED. Over the past decade, research and application of Micro-LED display technology have experienced rapid development.

[0003] Despite the rapid development of Micro-LED, full-color display technology remains a significant challenge and requires further in-depth research and development. For most display technologies, the displayed image requires three primary colors: red, green, and blue. Currently, there are two main types of colorization methods for Micro-LED full-color displays: the RGB method and the UV / blue LED color conversion method.

[0004] The three-color RGB method refers to the epitaxial growth and fabrication of red, green, and blue μLED chips on different substrates, followed by dicing and transfer to a target substrate. Currently, μLEDs are manufactured based on mature micro-solid-state technology, offering a more refined manufacturing process and higher resolution compared to conventional large-size LEDs. In μLEDs, blue and green LEDs are based on InGaN semiconductors, while AlGaInP semiconductors are used for red LEDs. To date, the most efficient purple and blue LEDs based on wide-bandgap GaN or InGaN alloys have several advantages, such as high efficiency, self-emissiveness, long lifetime, and ultra-high reliability in harsh environments. The external quantum efficiency (EQE) of InGaN-based blue LEDs has exceeded 80%, which is the most representative performance indicator for μLEDs. However, this method still has many drawbacks. The first problem is the lower efficiency of green μLEDs, known as the "green gap." For green μLEDs, a high proportion of In is required in the active region, which necessitates a relatively low growth temperature (approximately 700°C), resulting in poor crystal quality of the μLED epitaxial layer. Furthermore, a high proportion of In generates a strong polarization field in InGaN / GaN multiple quantum wells (MQWs), leading to a strong quantum confinement Stark effect and thus reducing recombination efficiency. Red μLEDs also present problems. Their active region is composed of AlGaInP material, exhibiting a large diffusion coefficient and surface recombination rate (approximately 10⁶ cm / s), making non-radiative surface recombination more significant. Therefore, as device size shrinks, the reduction in EQE in red μLEDs results in a more significant attenuation than in blue and green μLEDs, making it difficult to meet the high brightness requirements of AR / VR displays.

[0005] The three-color RGB method also faces another major challenge—mass transfer. The realization of μLED displays involves an ordered array of numerous RGB μLED chips, which are then transferred onto a receiving substrate and integrated into the optoelectronic system. The assembly process of μLED displays is based on two approaches. One technique involves dividing μLEDs into individual chips, which are picked up and transferred in groups from a parent wafer to a target substrate. This method allows for spatially free distribution of μLEDs and is used to manufacture large-size displays ranging from 2 inches to 70 inches. The other technique involves monolithically integrating μLEDs and then directly bonding the μLED chips to the backplane of the display assembly. This technique can achieve smaller μLED pixel pitches than mass transfer. However, due to the strict limitations of wafer size, monolithic integration is mainly used to manufacture small-size (<2 inches) displays. Because it can transfer more than 10,000 μLED chips at a time at high speed and low cost, mass transfer is considered the most important solution for large-scale, high-density, and full-color displays. Several μLED mass transfer technologies have emerged, including elastic imprinting, electrostatic transfer, electromagnetic transfer, laser-assisted transfer, and fluid self-assembly.

[0006] Typical flexible imprinting technology can operate μLEDs with a high transfer rate of 99.99%, and it typically offers a processing speed of 10,000 to 25,000 devices per hour. This means that assembling a 4K display composed of 25 million LEDs would take more than a month. Roller transfer may be a promising solution to the slow speed. However, imprint deformation issues impair flexible imprinting technology, leading to poor control and inaccurate pickup. Electrostatic and electromagnetic transfer technologies can achieve large-scale μLED transfer, but they can cause μLED breakdown due to the application of high voltage and require additional ferromagnetic layers respectively. Laser-assisted transfer technology can reach speeds of approximately 100 million times per hour with a placement error of 1.8 μm, but the transfer yield is as low as 90%. Fluid self-assembly achieves a high transfer rate of 56 million per hour at low cost, but it still requires further manufacturing improvements because modern displays are almost intolerant of defective pixels on the screen. To achieve perfect μLED image display, some schemes suggest replacing the defective pixel with a separate chip. Another approach is to transfer two μLEDs to each display pixel as a spare μLED chip. In summary, these mass transfer methods are either time-consuming or costly, making them difficult to implement for commercial purposes. Another problem with the three-color RGB method is the mismatch in driving voltages between the RGB pixels. The threshold voltage for blue LEDs is approximately 3.3 V, while the threshold voltages for red and green LEDs are 1.7 V and 2.2 V, respectively, which complicates the design of the driving circuit. Furthermore, the electro-optical conversion efficiency of the three-color RGB method varies with current density and device aging rates, which can easily cause visual color differences in displays.

[0007] The UV / blue LED + conversion material solution not only simplifies the driving circuitry but also reduces the assembly cycle. By overlaying a QD color conversion layer on the Micro-LED chip, higher color rendering and saturation can be achieved to meet the requirements of wide color gamut full-color displays. Furthermore, color compensation can be applied to individual color pixels (temperature, color shift, aging, etc.) to achieve a more comprehensive and intelligent high-quality display. Therefore, QD-based μLEDs for display applications have recently attracted increasing interest due to their potential advantages over LCD and OLED, namely high brightness, low power consumption, and low cost for large-size displays.

[0008] Quantum dots (QDs) are inorganic semiconductor nanocrystals with grain diameters between 2 and 10 nm, and are excellent materials for color conversion layers. Quantum dots possess unique photoelectric properties; when stimulated by light or electricity, they emit high-quality monochromatic light with extremely high color purity. The color of the light is determined by the constituent materials, size, and shape of the quantum dots. The most remarkable characteristic of these materials is the ability to tune the semiconductor bandgap by altering their size and discrete energy levels—the so-called quantum confinement effect. Currently, the main QD materials include CdSe, InP, and perovskite, offering high photoluminescence quantum yield (PLQY > 90%), high photostability, solution processability, and low manufacturing costs. QDs have a narrow full width at half maximum (FWHM) of approximately 20-30 nm, enabling the acquisition of intense and saturated colors, covering over 90% of the most stringent Rec. 2020 color gamut standard.

[0009] Currently, QD-based display technologies are developing primarily in two basic ways: one is based on photoluminescence QD-LED, where QD is a color conversion film in the LED backlight unit, in which quantum dots are physically embedded in a polymer matrix, sandwiched between two protective layers or on a blue light-emitting diode. The technological advantages of QD-LED displays include better color accuracy, higher color saturation, higher contrast, and higher peak brightness than traditional LCDs. Furthermore, compared to OLEDs, QD-LED technology offers better color purity (for OLEDs with an FWHM of approximately 100 nm), higher dynamic range, faster response time, and longer lifespan and durability due to improved thermal and atmospheric stability. These advantages make QD-LED technology ideal for producing ultra-high-definition displays. The superior performance of QD materials also makes them attractive for use in other display technologies to improve color conversion performance. Therefore, QD-based displays have received significant attention in the global market. Secondly, there's QLED, based on electroluminescence (EL). The QD layer is sandwiched between layers of organic materials used for electron and hole transport. An external electric field causes electrons and holes to recombine within the QD layer, emitting photons. Different colors can be displayed by controlling the inorganic composition and particle size, thus achieving screen display functionality. QLED has been a hot research topic for decades, receiving extensive study, although its full-size display commercialization has not yet arrived on the market. QLED performance is typically measured by EQE (Equivalent Value Expiration). CdSe quantum dot-based EL-LEDs have achieved an EQE of 19.8% for blue, 21% for green, and 20.5% for red, quickly catching up with QLEDs, which have an EQE of approximately 30%. QLED displays should surpass all competitors, including mainstream LED, OLED, and even QD-LED displays. However, QLED is still in the research stage, with many technical challenges yet to be overcome, and it remains far from commercial application. Once QLED technology achieves a breakthrough and mass production is possible, it will occupy a significant position in applications across micro-displays, small screens, medium screens, large screens, and ultra-large screens. Another major reason is that QLED has a much shorter lifespan than QD-LED. QD-LED displays have superior performance in terms of luminous efficiency, high electro-optical conversion efficiency, and long operating life, and are currently the mainstream in the market, represented by technology giants such as Samsung, Apple, BOE, and TCL.

[0010] Over nearly 40 years of research, QLED technology has made tremendous progress. In 2019, Shen et al. achieved a maximum external quantum efficiency of 22.9% and a maximum luminance of 614,000 cd / m² for their green QLED device. Also in 2019, Song et al. achieved a maximum external quantum efficiency of 30.9% and a maximum luminance of 334,000 cd / m² for their red QLED device. In 2020, Samsung of South Korea achieved a major breakthrough in blue QLEDs, fabricating a ZnTeSe / ZnSe / ZnS blue QLED with an external quantum efficiency of 20.2% and a maximum luminance of 88,900 cd / m². Summary of the Invention

[0011] In view of the challenges faced by Micro-LED full-colorization, including the low efficiency of red and green μLED chips and the immaturity of mass transfer, this invention introduces QLED display technology, combines red and green QLED with blue Micro-LED, and proposes a method for manufacturing a monolithically integrated Micro-LED and QLED hybrid full-color display device, which is also a novel Micro-LED full-colorization solution.

[0012] This invention proposes a monolithically integrated full-color display device combining Micro-LED and QLED. Its structural features include the epitaxial growth and etching of blue μLEDs and a bank on an epitaxial substrate, with red and green QLEDs located inside the bank. The red and green QLED structures, from bottom to top, are anode / hole injection layer / hole transport layer / quantum dot light-emitting layer / electron transport layer / cathode. The blue μLEDs and red and green QLEDs are horizontally distributed on the substrate, with the cathode of the blue μLED connected to the anode of the red and green QLEDs, and the anode of the blue μLED connected to the cathode of the red and green QLEDs.

[0013] The present invention specifically adopts the following technical solution:

[0014] A monolithic integrated structure for a hybrid Micro-LED and QLED full-color display device is characterized by: epitaxial growth and etching of a blue μLED and a bank on the same epitaxial substrate, wherein a red-green QLED is located inside the bank, and the red-green QLED structure from bottom to top consists of an anode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and a cathode; the blue μLED and the red-green QLED are horizontally distributed on the substrate, and the cathode of the blue μLED is connected to the anode of the red-green QLED, and the anode of the blue μLED is connected to the cathode of the red-green QLED.

[0015] Furthermore, each pixel unit includes 4 sub-pixels, namely red, green, blue, and green, arranged in RGGB;

[0016] Furthermore, the size of the sub-pixel does not exceed 100μm.

[0017] Furthermore, the blue sub-pixels and red-green sub-pixels are connected and driven in reverse parallel mode, that is, the cathode of the blue μLED is connected to the anode of the red-green QLED and shares a column electrode, and the anode of the blue μLED is connected to the cathode of the red-green QLED and shares a row electrode.

[0018] Furthermore, passive light emission is adopted, and the driver IC is externally mounted using TCP or COG connection; PWM driver dimming is adopted, and the brightness of the LED is controlled by changing the pulse width, thereby realizing the dimming control of the LED; and the blue and red-green light emission is precisely controlled separately by the forward and reverse pulse voltages.

[0019] Furthermore, red and green QLED pixels are fabricated on a structured blue Micro-LED substrate using inkjet printing technology to integrate a PM hybrid full-color display device.

[0020] Furthermore, the fabrication method of this integrated structure includes: growing a buffer layer, growing an n-type GaN layer, growing a quantum well layer, and growing a p-type GaN layer; then performing annealing and cleaning the LED epitaxial wafer to remove surface oxides and impurities;

[0021] The following steps are to be performed sequentially:

[0022] An ITO layer was deposited using an electron beam evaporation method, followed by rapid annealing and crystallization to form an ohmic contact layer;

[0023] A photolithography technique is used to create a mask, and the pattern on the mask is the shape and size of the required blue Micro-LED mesa and red and green QLED banks;

[0024] Using plasma etching technology, the material on the epitaxial wafer is etched onto the surface through a mask to expose the n-GaN layer, forming the desired shape and size of the bank for blue Micro-LEDs and red-green QLEDs;

[0025] Mask removal: The mask is removed using chemical or physical methods to expose the surface of p-type GaN and Bank.

[0026] A layer of ITO is deposited on the surface of n-type GaN on the bottom surface of p-type GaN and Bank;

[0027] Deep etching is performed to etch away the n-type GaN material on the epitaxial wafer through a mask, etching down to the sapphire, making each μLED and QLED independent, satisfying insulation, and forming the required complete blue Micro-LED and red-green QLED shape and size;

[0028] Bottom electrode fabrication: The bottom electrode is fabricated on the μLED epitaxial wafer;

[0029] Insulating layer preparation: A nanoscale patterned insulating layer material is deposited on the μLED epitaxial wafer, with the openings located above the p-type GaN of the μLED and inside the Bank of the QLED.

[0030] Inkjet-printed red-green QLEDs: Using full inkjet printing technology, the charge transport layer and quantum dot light-emitting layer of red-green QLEDs are sequentially deposited at different bank positions;

[0031] Top electrode fabrication: The top electrode is fabricated on the μLED epitaxial wafer.

[0032] Furthermore, the final step is encapsulation: the Micro-LED and QLED hybrid full-color display device is encapsulated using UV-resin.

[0033] Micro-LED and QLED are both future display technologies, theoretically possessing excellent display performance and application potential, and their fabrication processes are basically mature. However, traditional Micro-LED still faces core challenges in full-color technology, such as the low EQE efficiency of red-green μLED chips and the mass transfer technology of μLED chips. Regarding QLED technology, blue QLEDs are less efficient than red-green QLEDs. This invention and its preferred embodiment provide a method for monolithically integrating a hybrid full-color display device of blue Micro-LEDs and red-green QLEDs to achieve RGB three-color display. Red-green QLED pixels are fabricated on a structured blue Micro-LED substrate using inkjet printing technology, integrating a PM hybrid full-color display device. This technology avoids the technical difficulties of mass transfer, has a simple fabrication process, and can achieve high-efficiency display of RGB three colors, providing a novel full-color technology solution for the display field. Attached Figure Description

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0035] Figure 1 This is a front view of a monolithically integrated Micro-LED and QLED hybrid full-color display device structural unit in an embodiment of the present invention;

[0036] Figure 2 This is a process flow diagram of the blue μLED sub-pixel in an embodiment of the present invention;

[0037] Figure 3 This is a process flow diagram of the red and green QLED sub-pixels in an embodiment of the present invention;

[0038] Figure 4This is a planar structural diagram of a monolithically integrated Micro-LED and QLED hybrid full-color display device in an embodiment of the present invention;

[0039] Figure 5 (a) and (b) in the figure are planar structural diagrams of the blue μLED and red-green QLED sub-pixels in the embodiments of the present invention, respectively;

[0040] Figure 6 This is a schematic diagram of the pixel arrangement of a monolithically integrated Micro-LED and QLED hybrid full-color display device in an embodiment of the present invention. Detailed Implementation

[0041] To make the features and advantages of this patent more apparent and understandable, specific embodiments are provided below for detailed explanation:

[0042] It should be noted that the following detailed descriptions are exemplary 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.

[0043] 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.

[0044] like Figures 1-6 As shown in this embodiment, a monolithically integrated Micro-LED and QLED hybrid full-color display device is first proposed. Its structural feature is that a blue μLED and a bank are epitaxially grown and etched on an epitaxial substrate, wherein the red and green QLEDs are located inside the bank. The red and green QLED structure from bottom to top is anode / hole injection layer / hole transport layer / quantum dot light-emitting layer / electron transport layer / cathode. The blue μLED and the red and green QLED are horizontally distributed on the substrate. The cathode of the blue μLED is connected to the anode of the red and green QLED, and the anode of the blue μLED is connected to the cathode of the red and green QLED.

[0045] This method for monolithically integrating Micro-LED and QLED hybrid full-color display devices includes the following steps:

[0046] (1) Selecting a suitable substrate material: Sapphire, silicon, silicon carbide and other materials are usually selected as substrates;

[0047] (2) Prepare epitaxial growth equipment: Metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) equipment are usually used for epitaxial growth;

[0048] (3) Growth of buffer layer: A buffer layer is grown on the substrate to alleviate lattice mismatch and thermal stress between the substrate and the epitaxial layer;

[0049] (4) Growth of n-type GaN layer: In the epitaxial growth equipment, an n-type GaN layer is grown by controlling parameters such as temperature, pressure and gas flow rate;

[0050] (5) Growth of quantum well layers: In the epitaxial growth equipment, one or more quantum well layers are grown by controlling parameters such as temperature, pressure and gas flow rate. They are usually InGaN / GaN multi-quantum well structures.

[0051] (6) Growth of p-type GaN layer: In the epitaxial growth equipment, a p-type GaN layer is grown by controlling parameters such as temperature, pressure and gas flow rate;

[0052] (7) Annealing treatment: The epitaxial wafer is placed in an annealing furnace for annealing treatment to eliminate defects and stress generated during the epitaxial growth process;

[0053] (8) Clean the LED epitaxial wafer to remove oxides and dust impurities from its surface;

[0054] (9) An ITO layer is deposited by electron beam evaporation and then rapidly annealed and crystallized to form an ohmic contact layer;

[0055] (10) Mask fabrication: A mask is fabricated using photolithography. The pattern on the mask is the shape and size of the required blue Micro-LED mesa and red-green QLED bank.

[0056] (11) Etching the epitaxial wafer: Using plasma etching technology, the material on the epitaxial wafer is etched onto the surface through a mask to expose the n-GaN layer, forming the desired shape and size of the bank for the blue Micro-LED and red-green QLED;

[0057] (12) Mask removal: Remove the mask using chemical or physical methods to expose the p-type GaN and Bank surfaces;

[0058] (13) Deposit a layer of ITO on the surface of n-type GaN on the bottom surface of p-type GaN and Bank;

[0059] (14) Deep etching: Using photolithography and plasma etching technology, the n-type GaN material on the epitaxial wafer is etched away through a mask and etched into the sapphire, so that each μLED and QLED is independent, meets the insulation requirements, and forms the required complete blue Micro-LED and red-green QLED shape and size;

[0060] (15) Fabrication of bottom electrode: The bottom electrode is fabricated on the μLED epitaxial wafer. Photolithography, electron beam evaporation or sputtering are commonly used to fabricate the electrode.

[0061] (16) Insulating layer preparation: A nanoscale patterned insulating layer material is deposited on the μLED epitaxial wafer using photolithography, chemical vapor deposition and plasma etching. The openings are located above the p-type GaN of the μLED and inside the Bank of the QLED.

[0062] (17) Inkjet-printed red and green QLEDs: Using full inkjet printing technology, the charge transport layer and quantum dot light-emitting layer of red and green QLEDs are deposited sequentially at different Bank positions;

[0063] (18) Fabrication of the top electrode: The top electrode is fabricated on the μLED epitaxial wafer. Photolithography, electron beam evaporation or sputtering are commonly used to fabricate the electrode.

[0064] (19) Encapsulation: The Micro-LED and QLED hybrid full-color display device is encapsulated with UV-resin to protect the chip and improve light extraction efficiency.

[0065] Among them, as a preferred option, the substrate material includes, but is not limited to, sapphire, silicon, silicon carbide and other materials.

[0066] The epitaxial growth equipment used includes, but is not limited to, equipment such as metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE).

[0067] The thickness of the buffer layer, n-type GaN layer, multiple quantum well layer, and p-type GaN layer mentioned above will vary depending on the design and there is no fixed value; any reasonable value is acceptable.

[0068] The shapes of the blue Micro-LED platform and the red and green QLED bank include rectangles, rounded rectangles, circles, polygons, etc., and their sub-pixel sizes do not exceed 100 μm.

[0069] The banks used for printing QLEDs have the same inner diameter as those for blue μLEDs, and their width is not specifically limited.

[0070] The above uses inkjet printing to deposit the charge transport layer and the light-emitting layer. Its structure includes, but is not limited to, hole injection layer, hole transport layer, light-emitting layer, electron transport layer, charge blocking layer, and special isolation layer.

[0071] The annealing process for the inkjet-printed QLED sub-pixels described above includes, but is not limited to, nitrogen atmosphere and vacuum environment, with no limit on annealing temperature.

[0072] The QLED devices described above emit three colors: red, green, and blue, with sub-pixel sizes < 100 μm. Each pixel consists of four sub-pixels: red, green, blue, and green, arranged in an RGGB configuration. The blue sub-pixel is connected and driven in reverse parallel, meaning the cathode of the blue μLED is connected to the anode of the red-green QLED, sharing a column electrode; similarly, the anode of the blue μLED is connected to the cathode of the red-green QLED, sharing a row electrode. Passive matrix (PM) driving is used for light emission, and the driver IC needs to be externally mounted using TCP or COG connections. PMW (Pulse Width Modulation) dimming is employed, controlling the LED brightness by changing the pulse width, thus achieving dimming control. The blue and red-green light emission is precisely controlled separately by inverting the pulse voltage.

[0073] The following two specific application examples will further illustrate and explain the solution of this invention:

[0074] Example 1:

[0075] (1) Sapphire was selected as the substrate material;

[0076] (2) Prepare for epitaxial growth using a metal-organic chemical vapor deposition (MOCVD) apparatus;

[0077] (3) A u-GaN buffer layer is grown on the sapphire substrate to alleviate the lattice mismatch and thermal stress between the substrate and the epitaxial layer;

[0078] (4) In the MOCVD epitaxial growth equipment, by controlling parameters such as temperature, pressure and gas flow rate, an n-type GaN layer is grown on u-GaN;

[0079] (5) In the MOCVD epitaxial growth equipment, InGaN / GaN multi-quantum well layers are grown on the n-type GaN layer by controlling parameters such as temperature, pressure and gas flow rate;

[0080] (6) In the epitaxial growth equipment, a p-type GaN layer is grown on the MQWs layer by controlling parameters such as temperature, pressure and gas flow rate;

[0081] (7) The epitaxial wafer is placed in an annealing furnace for annealing treatment to eliminate defects and stress generated during the epitaxial growth process;

[0082] (8) Clean the GaN Micro-LED epitaxial wafer to remove surface oxides and dust impurities;

[0083] (9) An ITO layer is deposited by electron beam evaporation and then rapidly annealed and crystallized to form an ohmic contact layer;

[0084] (10) Use photolithography to make a mask with the pattern on the mask being the shape and size of the required blue Micro-LED mesa and red and green QLED banks;

[0085] (11) Using plasma etching technology, the material on the epitaxial wafer is etched onto the surface through a mask to expose the n-GaN layer, forming the desired shape and size of the bank for the blue Micro-LED and red-green QLED;

[0086] (12) Use a resist remover to remove the mask, exposing the surfaces of p-type GaN and Bank;

[0087] (13) Deposit a layer of ITO on the surface of n-type GaN on the bottom surface of p-type GaN and Bank;

[0088] (14) Using photolithography and plasma etching techniques, the n-type GaN material on the epitaxial wafer is deeply etched through a mask to the sapphire layer, so that each μLED and QLED is independent, meets the insulation requirements, and forms the required complete blue Micro-LED and red-green QLED shape and size;

[0089] (15) A bottom Ag electrode is fabricated on the μLED epitaxial wafer using photolithography and vapor deposition techniques, so that it is connected and conductive to n-GaN;

[0090] (16) Using photolithography, chemical vapor deposition and plasma etching, a layer of nanoscale SiO2 is deposited on the μLED epitaxial wafer and patterned as an insulating layer material, with the opening position above the p-type GaN of the μLED and inside the Bank of the QLED.

[0091] (17) Using full inkjet printing technology, the charge transport layer of red and green QLEDs and the quantum dot light-emitting layer are sequentially deposited at different Bank positions;

[0092] (18) A top Ag electrode is fabricated on a μLED epitaxial wafer using photolithography and vapor deposition techniques, and then connected to p-GaN via ITO;

[0093] (19) The Micro-LED and QLED hybrid full-color display device is encapsulated with UV-resin to protect the chip and improve light extraction efficiency.

[0094] Furthermore, the Micro-LED and QLED hybrid full-color device described in Embodiment 1 is composed of sub-pixels of three colors: blue LED and red-green QLED.

[0095] Furthermore, the thicknesses of the buffer layer, n-type GaN layer, multiple quantum well layer, and p-type GaN layer described in Example 1 may vary depending on the design.

[0096] Furthermore, in Embodiment 1, the blue Micro-LED's platform and the red-green QLED's bank are rounded rectangles with a sub-pixel size of 40 μm.

[0097] Furthermore, the bank used for printing QLEDs described in Embodiment 1 has the same inner diameter as the blue μLED, and the bank width is 5 μm;

[0098] Furthermore, in the QLED device described in Example 1, the hole injection layer, hole transport layer, light-emitting layer, and electron transport layer are completed using inkjet printing, and their materials are PEDOT:PSS, TFB, QDs (CdSe / ZnS), and ZnMgO, respectively.

[0099] Furthermore, the annealing treatment of the inkjet-printed QLED sub-pixels described in Example 1 is carried out under a nitrogen atmosphere, with annealing temperatures of 120°C, 120°C, 100°C, and 100°C, respectively.

[0100] Furthermore, the hybrid device described in Embodiment 1 has a pixel comprising four sub-pixels, namely red, green, blue, and green, arranged in RGGB.

[0101] Furthermore, in the hybrid device described in Embodiment 1, the blue sub-pixels and red-green sub-pixels are connected and driven in an anti-parallel manner, that is, the cathode of the blue μLED is connected to the anode of the red-green QLED and shares a column electrode. Similarly, the anode of the blue μLED is connected to the cathode of the red-green QLED and shares a row electrode.

[0102] Furthermore, the hybrid device described in Embodiment 1 employs passive matrix (PM) light emission, requiring the driver IC to be externally mounted via COG connection; it uses PMW (Pulse Width Modulation) for dimming, controlling the LED brightness by changing the pulse width, thereby achieving LED dimming control. Blue and red-green light emission are precisely controlled separately by inverting the pulse voltage.

[0103] Example 2:

[0104] (1) SiC was selected as the substrate material;

[0105] (2) Prepare for epitaxial growth using a molecular beam epitaxy (MBE) apparatus;

[0106] (3) A u-GaN buffer layer is grown on the sapphire substrate to alleviate the lattice mismatch and thermal stress between the substrate and the epitaxial layer;

[0107] (4) In the MBE epitaxial growth equipment, by controlling parameters such as temperature, pressure and gas flow rate, an n-type GaN layer is grown on u-GaN;

[0108] (5) In the MBE epitaxial growth equipment, InGaN / GaN multi-quantum well layers are grown on the n-type GaN layer by controlling parameters such as temperature, pressure and gas flow rate;

[0109] (6) In the epitaxial growth equipment, a p-type GaN layer is grown on the MQWs layer by controlling parameters such as temperature, pressure and gas flow rate;

[0110] (7) The epitaxial wafer is placed in an annealing furnace for annealing treatment to eliminate defects and stress generated during the epitaxial growth process;

[0111] (8) Clean the GaN Micro-LED epitaxial wafer to remove surface oxides and dust impurities;

[0112] (9) An ITO layer is deposited by electron beam evaporation and then rapidly annealed and crystallized to form an ohmic contact layer;

[0113] (10) Use photolithography to make a mask with the pattern on the mask being the shape and size of the required blue Micro-LED mesa and red and green QLED banks;

[0114] (11) Using plasma etching technology, the material on the epitaxial wafer is etched onto the surface through a mask to expose the n-GaN layer, forming the desired shape and size of the bank for the blue Micro-LED and red-green QLED;

[0115] (12) Use a resist remover to remove the mask, exposing the surfaces of p-type GaN and Bank;

[0116] (13) Deposit a layer of ITO on the surface of n-type GaN on the bottom surface of p-type GaN and Bank;

[0117] (14) Using photolithography and plasma etching techniques, the n-type GaN material on the epitaxial wafer is deeply etched through a mask to the sapphire layer, so that each μLED and QLED is independent, meets the insulation requirements, and forms the required complete blue Micro-LED and red-green QLED shape and size;

[0118] (15) A bottom Ag electrode is fabricated on the μLED epitaxial wafer using photolithography and vapor deposition techniques, so that it is connected and conductive to n-GaN;

[0119] (16) Using photolithography, chemical vapor deposition and plasma etching, a nanoscale Si3N4 layer is deposited on the μLED epitaxial wafer and patterned as an insulating layer material, with the opening position above the p-type GaN of the μLED and inside the Bank of the QLED.

[0120] (17) Using full inkjet printing technology, the charge transport layer of red and green QLEDs and the quantum dot light-emitting layer are sequentially deposited at different Bank positions;

[0121] (18) A top Al electrode is fabricated on a μLED epitaxial wafer using photolithography and vapor deposition techniques, and then connected to p-GaN via ITO;

[0122] (19) The Micro-LED and QLED hybrid full-color display device is encapsulated with UV-resin to protect the chip and improve light extraction efficiency.

[0123] Furthermore, the Micro-LED and QLED hybrid full-color device described in Embodiment 2 is composed of sub-pixels of three colors: blue LED and red-green QLED.

[0124] Furthermore, the thicknesses of the buffer layer, n-type GaN layer, multiple quantum well layer, and p-type GaN layer described in Example 21 may vary depending on the design.

[0125] Furthermore, in Embodiment 2, the blue Micro-LED's platform and the red-green QLED's bank are circular in shape, with a sub-pixel size of 50 μm.

[0126] Furthermore, the bank used for printing QLEDs described in Embodiment 2 has the same inner diameter as the blue μLED, and the bank width is 5 μm;

[0127] Furthermore, in the QLED device described in Example 2, the hole injection layer, hole transport layer, light-emitting layer, and electron transport layer are completed using inkjet printing, and the materials are PEDOT:PSS, CPB, QDs (InP / ZnSeS), and ZnMgO, respectively.

[0128] Furthermore, in the annealing process of the inkjet-printed QLED sub-pixels described in Example 2, the annealing conditions are a vacuum atmosphere, and the annealing temperatures are 110°C, 110°C, 90°C, and 90°C, respectively.

[0129] Furthermore, in the hybrid device described in Embodiment 2, the pixel includes four sub-pixels, namely red, green, blue, and green, arranged in RGGB.

[0130] Furthermore, in the hybrid device described in Embodiment 2, the blue sub-pixels and red-green sub-pixels are connected and driven in an anti-parallel manner, that is, the cathode of the blue μLED is connected to the anode of the red-green QLED and shares a column electrode. Similarly, the anode of the blue μLED is connected to the cathode of the red-green QLED and shares a row electrode.

[0131] Furthermore, the hybrid device described in Embodiment 2 employs passive matrix (PM) light emission, requiring the driver IC to be externally mounted via COG connection; it uses PMW (Pulse Width Modulation) for dimming, controlling the LED brightness by changing the pulse width, thereby achieving LED dimming control. Blue and red-green light emission are precisely controlled separately by inverting the pulse voltage.

[0132] This patent is not limited to the above-described preferred embodiments. Anyone can derive other forms of integrated structure and fabrication method of Micro-LED and QLED hybrid full-color display device based on the teachings of this patent. All equivalent changes and modifications made within the scope of the claims of this invention shall fall within the scope of this patent.

Claims

1. A monolithic integrated structure for a hybrid Micro-LED and QLED full-color display device, characterized in that: The blue μLED and the Bank are epitaxially grown on the same epitaxial substrate, wherein the red and green QLEDs are located inside the Bank, and the red and green QLED structure from bottom to top comprises an anode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and a cathode; the blue μLED and the red and green QLED are horizontally distributed on the substrate, the cathode of the blue μLED is connected with the anode of the red and green QLED, and the anode of the blue μLED is connected with the cathode of the red and green QLED; Each pixel unit comprises four sub-pixels, which are red, green, blue and green respectively, and the arrangement mode is RGGB; The blue sub-pixel and the red and green sub-pixel are connected and driven in a reverse parallel mode, that is, the cathode of the blue μLED is connected with the anode of the red and green QLED, and shares a column electrode, and the anode of the blue μLED is connected with the cathode of the red and green QLED, and shares a row electrode; Passive driving is adopted for light emission, and the IC is externally mounted by TCP or COG connection mode; PMW driving is adopted for dimming, the brightness of the LED is controlled by changing the pulse width, so as to realize the dimming control of the LED; and the blue and red and green light emission is accurately controlled by the positive and negative pulse voltage respectively; Photoetching and plasma etching technology are used to etch the n-type GaN material on the epitaxial wafer through a mask, and the sapphire substrate is etched, so that each μLED and QLED is independent and meets the insulation requirement. 2.The micro-LED and QLED hybrid full-color display device monolithic integrated structure of claim 1, wherein: The size of the sub-pixel is not more than 100 μm.

3. The method of claim 1, wherein the method further comprises: Red and green QLED pixels are prepared on a structured blue Micro-LED substrate by inkjet printing technology to integrate a PM mixed full-color display device.

4. The method of claim 1, comprising: A buffer layer is grown, an n-type GaN layer is grown, a quantum well layer is grown, and a p-type GaN layer is grown; Then, annealing treatment and cleaning of the LED epitaxial wafer are performed to remove the surface oxides and impurities; It is characterized in that: the following steps are sequentially performed: An ITO layer is deposited by an electron beam evaporation scheme, and is quickly annealed and crystallized to form an ohmic contact layer; A mask is made using photoetching technology, and the pattern on the mask is the shape and size of the required blue Micro-LED mesa and red and green QLED Bank; Using plasma etching technology, the material on the epitaxial wafer is etched out of the mesa through the mask to expose the n-GaN layer, and the shape and size of the required blue Micro-LED and red and green QLED Bank are formed; The mask is removed: the mask is removed by chemical or physical method, and the surface of the p-type GaN and the Bank is exposed; An ITO layer is deposited on the n-type GaN surface of the p-type GaN and the Bank inner bottom surface; Deep etching is performed: the n-type GaN material on the epitaxial wafer is etched away through the mask to the sapphire substrate, so that each μLED and QLED is independent and meets the insulation requirement, and the required complete blue Micro-LED and red and green QLED shape and size are formed; Bottom electrode preparation: a bottom electrode is prepared on the μLED epitaxial wafer; The insulating layer is prepared, a nanoscale patterned insulating layer material is deposited on the μLED epitaxial wafer, and the opening position is above the p-type GaN of the μLED and inside the Bank of the QLED; Inkjet printing red and green QLED: using full inkjet printing technology, the charge transport layer and quantum dot light emitting layer of red and green QLED are deposited in different Bank positions in turn; Top electrode preparation: top electrode is prepared on the μLED epitaxial wafer.

5. The method of claim 4, wherein the method further comprises: Finally, the packaging is carried out: the Micro-LED and QLED mixed full-color display device is packaged using UV-resin.

Images