Light-emitting device, preparation method thereof and display device

Abstract

The invention provides a light-emitting device and a preparation method thereof, and a display device, the light-emitting device comprises a plurality of first light-emitting units, each first light-emitting unit comprises a first quantum well layer and a second quantum well layer, and the second quantum well layer is located at one side, close to the light-emitting side of the light-emitting device, of the first quantum well layer; wherein the first quantum well layer is used for emitting light of a first color, the second quantum well layer is used for emitting light of a second color based on the light of the first color, and the wavelength of the light of the first color is smaller than that of the light of the second color.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of display, and in particular, to a light emitting device and a preparation method therefor, and a display device. BACKGROUND

[0002] The full-color technology of Micro Light Emitting Diode (Micro-LED) display mainly includes three-color RGB method, ultraviolet / blue light Micro-LED + light conversion material method, and lens synthesis method. The three-color RGB method realizes full-color display by transferring red, green and blue Micro-LED dies respectively. When used for large-pixel display structure, the number of chips to be transferred is large and the difficulty is high, and the red light LED efficiency is not high. The ultraviolet / blue light Micro-LED + light conversion material method has high requirements for the reliability and wavelength consistency of light conversion materials, and the light conversion materials mainly include quantum dots and fluorescent powder. The particle size of the fluorescent powder material is large, which easily causes uneven deposition; the size of the quantum dot material is small, but it has problems such as poor stability and short service life. The lens synthesis method needs to encapsulate red, green and blue Micro LED arrays respectively and use optical prism to synthesize full-color display. Although this method is simple, its application range is narrow, mainly limited to the construction of projection equipment.

[0003] The above information disclosed in this section is only for the understanding of the background of the inventive concept of the present disclosure, and therefore, the above information can contain information that does not constitute the prior art. SUMMARY

[0004] In one aspect, a light emitting device is provided, the light emitting device comprising a plurality of first light emitting units, the first light emitting units comprising a first quantum well layer and a second quantum well layer; the second quantum well layer being located on a side of the first quantum well layer close to an out-light side of the light emitting device; wherein the first quantum well layer is configured to emit light of a first color, and the second quantum well layer is configured to emit light of a second color based on the light of the first color, the light of the first color having a wavelength smaller than the light of the second color.

[0005] According to some exemplary embodiments, the light of the first color is blue light.

[0006] According to some exemplary embodiments, the light emitting device further comprises a plurality of second light emitting units, the second light emitting units comprising the first quantum well layer.

[0007] According to some exemplary embodiments, the light-emitting device further comprises a plurality of third light-emitting units, the third light-emitting unit comprising the first quantum well layer and a first quantum dot layer; the first quantum dot layer is located on a side of the first quantum well layer close to a light-emitting side of the light-emitting device; wherein the first quantum dot layer is configured to emit light of a third color based on the blue light, the light of the third color having a wavelength greater than that of the blue light.

[0008] According to some exemplary embodiments, the light-emitting device further comprises a black matrix layer and a first color resistance layer; the black matrix layer is located on a side of the second quantum well layer away from the first quantum well layer, the black matrix layer comprises a plurality of first openings, a normal projection of the third light-emitting unit on the black matrix layer at least partially overlaps with the first opening; the first color resistance layer is located in the first opening; wherein the first quantum dot layer is located in the first opening and between the first color resistance layer and the first quantum well layer.

[0009] According to some exemplary embodiments, in the light-emitting direction of the light-emitting device, the sum of the thickness of the first quantum dot layer and the thickness of the first color resistance layer is substantially equal to the thickness of the black matrix layer.

[0010] According to some exemplary embodiments, the light-emitting device further comprises a plurality of third light-emitting units, the third light-emitting unit comprising the first quantum well layer and a third quantum well layer; the third quantum well layer is located on a side of the first quantum well layer close to a light-emitting side of the light-emitting device; wherein the third quantum well layer is configured to emit light of a third color based on the blue light, the light of the third color having a wavelength greater than that of the blue light.

[0011] According to some exemplary embodiments, the light of the second color is green light, and the light of the third color is red light; or the light of the second color is red light, and the light of the third color is green light.

[0012] According to some exemplary embodiments, the light of the first color is ultraviolet light, and the light of the second color is any one of red light, green light, and blue light.

[0013] According to some exemplary embodiments, the light-emitting device further comprises a first electrode layer and a second electrode layer; the first electrode layer comprises a plurality of first electrodes, the first electrode is located on a side of the first quantum well layer away from the second quantum well layer; the second electrode layer is located on a side of the second quantum well layer away from the first quantum well layer.

[0014] According to some exemplary embodiments, the light-emitting device further comprises a separation layer, the separation layer is located between two adjacent quantum well layers in the light-emitting direction of the light-emitting device.

[0015] In another aspect, a display device is provided, which includes the light emitting device as described above and a driving backplane, the driving backplane being located on a side of the first quantum well layer away from the second quantum well layer.

[0016] In yet another aspect, a method for manufacturing a light emitting device is provided, which includes: forming a second quantum well material layer on a substrate; patterning the second quantum well material layer to form a second quantum well layer; forming a first quantum well material layer on a side of the second quantum well layer away from the substrate; patterning the first quantum well material layer to form a first quantum well layer, the side of the second quantum well layer away from the first quantum well layer being a light emitting side of the light emitting device, the first quantum well layer being configured to emit light of a first color, the second quantum well layer being configured to emit light of a second color based on the light of the first color, the light of the first color having a wavelength smaller than the light of the second color.

[0017] According to some example embodiments, the method for manufacturing a light emitting device further includes: forming a black matrix layer on the side of the second quantum well layer away from the first quantum well layer, the black matrix layer including a plurality of first openings, a projection of the second quantum well layer on the black matrix layer having no overlap with the first openings; forming a first quantum dot layer within the first openings, the first quantum dot layer being configured to emit light of a third color based on the light of the first color, the light of the third color having a wavelength larger than the light of the first color; and forming a first color resist layer on a side of the first quantum dot layer away from the first quantum well layer.

[0018] According to some example embodiments, before forming the second quantum well material layer on the substrate, the method for manufacturing a light emitting device further includes: forming a third quantum well material layer on the substrate; patterning the third quantum well material layer to form a third quantum well layer, the third quantum well layer being configured to emit light of a third color based on the light of the first color, the light of the third color having a wavelength larger than the light of the first color. BRIEF DESCRIPTION OF DRAWINGS

[0019] Other objects and advantages of the present disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0020] Figure 1 A structural schematic diagram of a display device according to some embodiments of the present disclosure is schematically shown.

[0021] Figure 2 A structural schematic diagram of a display device according to some other embodiments of the present disclosure is schematically shown.

[0022] Figure 3 A structural schematic of a display device according to yet other embodiments of the present disclosure is schematically illustrated.

[0023] Figure 4 A flowchart of a method of fabricating a light emitting device according to some embodiments of the present disclosure is schematically illustrated.

[0024] Figures 5a to 5g Structural schematics of components in a fabrication process flow of a display device according to some embodiments of the present disclosure are schematically illustrated.

[0025] Figure 6 A transmission electron microscope cross-sectional view of a second quantum well layer emitting green light based on blue light according to some embodiments of the present disclosure is schematically illustrated.

[0026] Figure 7 A spectrum plot of a second quantum well layer emitting green light based on blue light according to some embodiments of the present disclosure is schematically illustrated.

[0027] Figures 8a to 8i Structural schematics of components in a fabrication process flow of a display device according to other embodiments of the present disclosure are schematically illustrated. DETAILED DESCRIPTION

[0028] In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the various exemplary embodiments. It is apparent, however, that various exemplary embodiments can be practiced without using these specific details or with one or more equivalent arrangements. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the various exemplary embodiments. Additionally, various exemplary embodiments can be different from one another and still come within the scope of the inventive concepts.

[0029] In the drawings, the size and relative sizes of elements can be exaggerated for clarity and / or descriptive purposes. As such, the dimensions and relative sizes of various elements can not be to scale. When an example embodiment is described as comprising, including, or having an element or a plurality of elements, the element or elements can be and are also comprised, included, or housed in, as appropriate, one or more other example embodiments, where such other example embodiments are not also described as comprising, including, or having the one or more other elements. Unless otherwise noted, the same reference numerals are used throughout the drawings and the following description to refer to the same or like parts.

[0030] When an element is referred to as being "on" another element, "connected to" another element, or "coupled to" another element, it can be directly on, directly connected to, or directly coupled to the other element or intervening elements can be present. In contrast, when an element is referred to as being "directly on," "directly connected to," or "directly coupled to" another element, there are no intervening elements present. Other terms of relationship can be interpreted in a similar manner, such as "between" versus "directly between," "adjacent" versus "directly adjacent," or "on" versus "directly on," etc. In addition, the term "connected" can refer to physical or electrical connection, communication connection, and / or fluid connection.

[0031] It should be understood that, although the terms first, second, etc. can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the example embodiments.

[0032] In the related art, when the tricolor RGB method is used for a large-pixel display structure, the number of chips to be transferred is large and the difficulty is high, and the efficiency of red light LEDs is not high. The ultraviolet / blue light Micro-LED+light conversion material method has high requirements for the reliability and wavelength consistency of the light conversion material, and the light conversion material mainly includes quantum dots and fluorescent powder. Since the particle size of the fluorescent powder material is large, it is easy to cause uneven deposition; the size of the quantum dot material is small, but it has problems such as poor stability and short service life. Although the lens synthesis method is simple, its range of use is relatively narrow, and is mainly limited to the construction of projection equipment. Therefore, in order to solve at least one aspect of the above technical problems, the embodiments of the present disclosure provide a light emitting device and a preparation method thereof, and a display device, which can avoid mass transfer and be beneficial to reduce the cost.

[0033] Figure 1 FIG. 1 is a structural schematic diagram of a display device according to some embodiments of the present disclosure.

[0034] Reference Figure 1The display device includes a light emitting device and a driving backboard 900. The light emitting device includes a plurality of first light emitting units 100, and each of the first light emitting units 100 includes a first quantum well layer 101 and a second quantum well layer 102. The second quantum well layer 102 is located on a side of the first quantum well layer 101 close to a light emitting side of the light emitting device. The driving backboard 900 is located on a side of the first quantum well layer 101 away from the second quantum well layer 102. The first quantum well layer 101 is configured to emit light of a first color, and the second quantum well layer 102 is configured to emit light of a second color based on the light of the first color. The light of the first color has a shorter wavelength than the light of the second color. The driving backboard 900 includes a plurality of CMOS circuits, and a surface of the driving backboard 900 is provided with a plurality of conductive pads respectively connected to the CMOS circuits. The light emitting device can be electrically connected to the CMOS circuits through the conductive pads, so that the CMOS circuits provide driving signals for the light emitting device.

[0035] It should be noted that the first quantum well layer 101 and the second quantum well layer 102 are formed by an epitaxial growth process (for example, a metal-organic chemical vapor deposition (MOCVD) process). The epitaxial growth process has many advantages, such as high crystal quality and surface flatness, precise control of growth conditions and thickness, and the like, to improve the light emitting efficiency and performance of the light emitting device. Compared with the mass transfer process, the epitaxial growth process simplifies the process flow and can effectively reduce the production cost.

[0036] It can be understood that the second quantum well layer 102 can be excited by the light of the first color emitted by the first quantum well layer 101 to generate light of the second color. Specifically, the first quantum well layer 101 is electroluminescence, and the second quantum well layer 102 is photoluminescence. The principle of photoluminescence is that after a substance absorbs photons of a specific wavelength, the electrons jump from the ground state to the excited state, and then release energy by radiation or non-radiation and return to the ground state, and finally emit light in the form of photons. In this embodiment, the first quantum well layer 101 is epitaxially grown to emit light of a shorter wavelength, and the second quantum well layer 102 is epitaxially grown to emit light of a longer wavelength, so as to obtain pure light of the second color. This can reduce the preparation cost of the light emitting device, avoid the difficulty of mass transfer, and realize low-cost and high pixel density (PPI) display.

[0037] In some embodiments of the present disclosure, the light-emitting device further comprises a first electrode layer 600 and a second electrode layer 700. The first electrode layer 600 comprises a plurality of first electrodes 601, which are located on the side of the first quantum well layer 101 away from the second quantum well layer 102. The second electrode layer 700 is located on the side of the second quantum well layer 102 away from the first quantum well layer 101.

[0038] It should be noted that the first electrode layer 600 can be a P electrode layer, which is connected to a power supply voltage; and the second electrode layer 700 can be an N electrode layer, which is connected to a reference voltage. In the present embodiment, the first quantum well layer 101 is electroluminescent. In the process of electroluminescence, electrons and holes are injected into the first quantum well layer 101 by an external electric field (i.e., an electric field formed between the first electrode layer 600 and the second electrode layer 700), efficient carrier recombination is achieved in the first quantum well layer 101, and photons are emitted through the energy released in the recombination process, thereby obtaining light of the first color. The P electrode layer is, for example, a gallium nitride layer (GaN) doped with magnesium (Mg), the doping concentration of Mg is greater than or equal to 1.0E20 atoms per cubic centimeter, the thickness of the P electrode layer is greater than or equal to 50 nanometers and less than or equal to 200 nanometers, and the thickness of the P electrode layer is, for example, any one of 50 nanometers, 80 nanometers, 100 nanometers, 150 nanometers, and 200 nanometers. The N electrode layer is, for example, a transparent conductive layer such as indium tin oxide (Indium Tin Oxide, abbreviated as ITO), indium zinc oxide (Indium Zinc Oxide, abbreviated as IZO), and thin metal.

[0039] In some embodiments of the present disclosure, the light-emitting device further comprises a separation layer 800, which is located between two adjacent quantum well layers in the light-emitting direction of the light-emitting device.

[0040] It can be understood that, due to the high metal content in the second quantum well layer 102, the quality of the crystal grown epitaxially directly on the second quantum well layer 102 is poor and has many defects. In the present embodiment, by providing the separation layer 800 between the two adjacent quantum well layers (i.e., between the first quantum well layer 101 and the second quantum well layer 102), the interface is transitioned, and a good growth surface is provided for the subsequent growth of the first quantum well layer 101, thereby improving the crystal quality of the first quantum well layer 101. The separation layer 800 is, for example, an undoped gallium nitride layer, and the thickness of the separation layer 800 is greater than or equal to 2 nanometers and less than or equal to 8 nanometers. The thickness of the separation layer 800 is, for example, any one of 2 nanometers, 4 nanometers, 6 nanometers, 7 nanometers, and 8 nanometers.

[0041] In some embodiments of the present disclosure, the light of the first color is blue light. That is, the first quantum well layer 101 is a blue light quantum well layer, and the second quantum well layer 102 emits light of a second color based on the blue light, for example, red light or green light. The blue light quantum well layer is, for example, a multi-layer structure of alternating indium gallium nitride (InGaN) and gallium nitride (GaN). The indium gallium nitride is a quantum well, and the thickness of the indium gallium nitride is greater than or equal to 1 nanometer and less than or equal to 5 nanometers, for example, any one of 1 nanometer, 2 nanometers, 3 nanometers, 4 nanometers, or 5 nanometers. The gallium nitride is a quantum barrier, and the thickness of the gallium nitride is greater than or equal to 8 nanometers and less than or equal to 20 nanometers, for example, any one of 8 nanometers, 10 nanometers, 12 nanometers, 16 nanometers, or 20 nanometers. One quantum well and one quantum barrier form a pair, and the blue light quantum well layer includes greater than or equal to 3 pairs and less than or equal to 10 pairs of quantum wells and quantum barriers, for example, any one of 3 pairs, 5 pairs, 6 pairs, 8 pairs, or 10 pairs of quantum wells and quantum barriers. In the blue light quantum well layer, the ratio of the number of indium atoms (In) to the sum of the number of indium atoms and the number of gallium atoms (In+Ga) is greater than or equal to 5% and less than or equal to 15%, for example, any one of 5%, 8%, 10%, 12%, or 15% of In / (In+Ga).

[0042] In some embodiments of the present disclosure, the light-emitting device further includes a plurality of second light-emitting units 200, and each second light-emitting unit 200 includes the first quantum well layer 101. That is, in the present embodiment, a part of the blue light quantum well layer serves as a light-emitting layer of the second light-emitting unit 200, and the blue light quantum well layer of the second light-emitting unit 200 and the blue light quantum well layer of the first light-emitting unit 100 can be prepared by the same epitaxial process and separated by patterning, thereby simplifying the preparation process of the light-emitting device.

[0043] In some embodiments of the present disclosure, the light-emitting device further includes a plurality of third light-emitting units 300, and each third light-emitting unit 300 includes the first quantum well layer 101 and a first quantum dot layer 301. The first quantum dot layer 301 is located on the side of the first quantum well layer 101 close to the light-emitting side of the light-emitting device. The first quantum dot layer 301 is configured to emit light of a third color based on the blue light, and the wavelength of the light of the third color is greater than the wavelength of the blue light. That is, in the present embodiment, a part of the blue light quantum well layer serves as an excitation light source of the third light-emitting unit 300, and the first quantum dot layer 301 serves as a color conversion layer and emits light of the third color under the excitation of the blue light quantum well layer. The first quantum dot layer 301 can be prepared by printing, and compared with the epitaxial growth process, the first quantum dot layer 301 of the third light-emitting unit 300 prepared by printing is faster, thereby improving the preparation efficiency of the light-emitting device.

[0044] In some embodiments of the present disclosure, the second color of light is green light, and the third color of light is red light; or, the second color of light is red light, and the third color of light is green light. That is, the second quantum well layer 102 can be a green light quantum well layer, and the first quantum dot layer 301 can be a red light quantum dot layer; or, the second quantum well layer 102 is a red light quantum well layer, and the first quantum dot layer 301 is a green light quantum dot layer. Since the manufacturing difficulty of the red light quantum well layer is greater than that of the green light quantum well layer, it is preferred that the second quantum well layer 102 is a green light quantum well layer, and the first quantum dot layer 301 is a red light quantum dot layer, so as to further simplify the preparation process of the light emitting device.

[0045] It can be understood that, in the present embodiment, the first quantum well layer 101 is epitaxially grown as an excitation light source, and also as a blue light source; the second quantum well layer 102 is epitaxially grown as a second color color conversion layer, and the first quantum dot layer 301 manufactured by the printing process is a third color color conversion layer, which can be a red light source and a green light source, respectively, so that full-color display of the light emitting device can be realized.

[0046] It should be noted that the structure of the green light quantum well layer and the red light quantum well layer is similar to that of the blue light quantum well layer, except that the ratio of the number of indium atoms (In) to the sum of the number of indium atoms and the number of gallium atoms (In+Ga) is different. In some embodiments, in the green light quantum well layer, the ratio of the number of indium atoms (In) to the sum of the number of indium atoms and the number of gallium atoms (In+Ga) is greater than or equal to 15% and less than or equal to 25%, for example, In / (In+Ga) is any one of 15%, 18%, 20%, 22%, and 25%. In some embodiments, in the red light quantum well layer, the ratio of the number of indium atoms (In) to the sum of the number of indium atoms and the number of gallium atoms (In+Ga) is greater than or equal to 25% and less than or equal to 35%, for example, In / (In+Ga) is any one of 25%, 28%, 30%, 32%, and 35%.

[0047] In some embodiments of the present disclosure, the light emitting device further comprises a black matrix layer 400 and a first color resistance layer 501. The black matrix layer 400 is located on the side of the second quantum well layer 102 away from the first quantum well layer 101, and the black matrix layer 400 comprises a plurality of first openings 401, and the orthogonal projection of the third light emitting unit 300 on the black matrix layer 400 at least partially overlaps the first openings 401. The first color resistance layer 501 is located in the first openings 401. Among them, the first quantum dot layer 301 is located in the first openings 401, and between the first color resistance layer 501 and the first quantum well layer 101.

[0048] It can be understood that, in the embodiment, by arranging the black matrix layer 400 on the side of the second quantum well layer 102 away from the first quantum well layer 101 (i.e., the light-emitting side of the light-emitting device) and arranging the first color resistance layer 501 in the first opening 401 of the black matrix layer 400, the color purity of the light of the third color can be improved. By forming the first quantum dot layer 301 in the first opening 401 through a printing process, one process of patterning the first quantum dot layer 301 can be reduced. In other embodiments, the first quantum dot layer 301 can also be manufactured by a photolithography process, and the embodiments of the present disclosure are not limited thereto.

[0049] In some embodiments, the light-emitting device further comprises a second color resistance layer 502 and a third color resistance layer 503. The black matrix layer 400 comprises a plurality of second openings 402 and a plurality of third openings 403, and the orthographic projection of the first light-emitting unit 100 on the black matrix layer 400 at least partially overlaps the second opening 402, and the orthographic projection of the second light-emitting unit 200 on the black matrix layer 400 at least partially overlaps the third opening 403. The second color resistance layer 502 is located in the second opening 402 and is used to improve the color purity of the light of the second color; and the third color resistance layer 503 is located in the third opening 403 and is used to improve the color purity of the light of the first color.

[0050] Reference Figure 1 In some embodiments of the present disclosure, the sum of the thickness d1 of the first quantum dot layer 301 and the thickness d2 of the first color resistance layer 501 in the light-emitting direction of the light-emitting device is substantially equal to the thickness d3 of the black matrix layer 400. That is, within the range allowed by the process error, the sum (d1+d2) of the thickness d1 of the first quantum dot layer 301 and the thickness d2 of the first color resistance layer 501 is substantially equal to the thickness d3 of the black matrix layer 400, so that the surface of the color filter layer (composed of the first color resistance layer 501, the second color resistance layer 502, and the third color resistance layer 503) remains flat.

[0051] In some embodiments of the present disclosure, the light-emitting device further comprises an epitaxial layer 13 located between the second electrode layer 700 and the second quantum well layer 102. In the direction opposite to the light-emitting direction of the light-emitting device, the epitaxial layer 13 comprises a first N-type gallium nitride layer, an aluminum gallium nitride layer, a second N-type gallium nitride layer, and a superlattice layer arranged in sequence. Among them, silicon (Si) is doped in the first N-type gallium nitride layer and the second N-type gallium nitride layer, and the doping concentration is greater than or equal to 1.0*10 19 atoms / cm3 and less than or equal to 5*10 19 atoms / cm3, for example, 1.0*10 19 atoms / cm3, 2*10 19 atoms / cm3, 3*10 19 atoms / cm3, 4*10 19Number of atoms per cubic centimeter, 5*10 19 Any value in the number of atoms per cubic centimeter.

[0052] It is understood that, due to the different lattices of the aluminum gallium nitride (AGaN) layer and the gallium nitride (GaN) layer, by placing the AGaN layer between the first N-type GaN layer and the second N-type GaN layer, the interfacial stress can be adjusted and dislocations filtered. In some embodiments, in the first N-type GaN layer, the AGaN layer, and the second N-type GaN layer, the ratio of aluminum atoms (Al) to the sum of aluminum and gallium atoms (Al+Ga) is greater than or equal to 3% and less than or equal to 15%, for example, Al / (Al+Ga) is any value among 3%, 8%, 10%, 12%, and 15%. In some embodiments, along the light emission direction of the light-emitting device, the sum of the thicknesses of the first N-type GaN layer, the AGaN layer, and the second N-type GaN layer is greater than or equal to 10 nanometers and less than or equal to 50 nanometers, for example, any value among 10 nanometers, 20 nanometers, 30 nanometers, 40 nanometers, and 50 nanometers.

[0053] It is understood that, in this embodiment, by setting a superlattice layer as a stress relief layer and a growth interruption layer, the quality of the epitaxial layer 13 can be improved. The superlattice layer is, for example, a multi-layer structure with alternating indium gallium nitride (InGaN) and gallium nitride (GaN). The thickness of the indium gallium nitride is greater than or equal to 1 nm and less than or equal to 5 nm, for example, any value among 1 nm, 2 nm, 3 nm, 4 nm, and 5 nm; the thickness of the gallium nitride is greater than or equal to 15 nm and less than or equal to 30 nm, for example, any value among 15 nm, 18 nm, 20 nm, 25 nm, and 30 nm. One indium gallium nitride and one gallium nitride form a pair, and the superlattice layer includes, for example, 4 or 5 pairs of indium gallium nitride and gallium nitride. In the superlattice layer, the ratio of indium atoms (In) to the sum of indium and gallium atoms (In+Ga) is greater than or equal to 1% and less than or equal to 5%, for example, In / (In+Ga) is any value among 1%, 2%, 3%, 4%, and 5%.

[0054] In some embodiments of this disclosure, the light-emitting device further includes an electron-blocking layer (EBL) located between the first quantum well layer 101 and the first electrode 601. It is understood that, in this embodiment, by providing the electron-blocking layer, electrons within the first quantum well layer 101 can be prevented from leaking to the first electrode 601, thus confining more electrons within the first quantum well layer 101 to participate in radiative recombination, thereby improving the luminous efficiency of the first quantum well layer 101. The electron-blocking layer may be, for example, an aluminum gallium nitride layer (AlGaN).

[0055] In some embodiments of this disclosure, the light-emitting device further includes an insulating layer 14 located between two adjacent light-emitting units. It is understood that, since the driving backplate 900 needs to be bonded to the first electrode 601 of the light-emitting device to achieve electrical connection, the insulating layer 14 does not cover the first electrode 601. In some embodiments, the bonding type between the driving backplate 900 and the first electrode 601 is, for example, conductive bonding such as copper / tin, gold / tin, copper / indium, gold / indium, or anisotropic conductive film (ACF).

[0056] Figure 2 This is a schematic diagram of the structure of a display device according to some other embodiments of the present disclosure.

[0057] Reference Figure 2 The display device includes a light-emitting device and a driving backplate 900. The light-emitting device includes a plurality of first light-emitting units 100, each first light-emitting unit 100 including a first quantum well layer 101 and a second quantum well layer 102. The second quantum well layer 102 is located on the side of the first quantum well layer 101 closest to the light-emitting side of the light-emitting device. The driving backplate 900 is located on the side of the first quantum well layer 101 furthest from the second quantum well layer 102. The first quantum well layer 101 emits light of a first color, and the second quantum well layer 102 emits light of a second color based on the first color light, wherein the wavelength of the first color light is shorter than the wavelength of the second color light.

[0058] In some embodiments of this disclosure, the first color of light is blue light. That is, the first quantum well layer 101 is a blue light quantum well layer, and the second quantum well layer 102 emits a second color of light based on the blue light, such as red or green light. The structure and film composition of the blue light quantum well layer are as follows: Figure 1 The structure and film composition of the blue quantum well layer in the illustrated embodiment are the same, and will not be described again here.

[0059] In some embodiments of this disclosure, the light-emitting device further includes a plurality of second light-emitting units 200, each second light-emitting unit 200 including a first quantum well layer 101. That is, in this embodiment, a portion of the blue quantum well layer serves as the light-emitting layer of the second light-emitting unit 200.

[0060] In some embodiments of this disclosure, the light-emitting device further includes multiple third light-emitting units 300, each comprising a first quantum well layer 101 and a third quantum well layer 302. The third quantum well layer 302 is located on the side of the first quantum well layer 101 closest to the light-emitting side of the light-emitting device. The third quantum well layer 302 is used to emit light of a third color based on blue light, the wavelength of which is greater than the wavelength of blue light. That is, in this embodiment, a portion of the blue quantum well layer serves as the excitation source for the third light-emitting unit 300, and the third quantum well layer 302 serves as a color-conversion layer, emitting light of the third color under the excitation of the blue quantum well layer. Since the first quantum well layer 101, the second quantum well layer 102, and the third quantum well layer 302 are all fabricated using epitaxial growth technology and are all inorganic layers, their reliability is higher.

[0061] In some embodiments of this disclosure, the second color light is green light and the third color light is red light; or, the second color light is red light and the third color light is green light. That is, the second quantum well layer 102 can be a green quantum well layer and the third quantum well layer 302 can be a red quantum well layer; or, the second quantum well layer 102 is a red quantum well layer and the third quantum well layer 302 is a green quantum well layer. The structure and film composition of the green and red quantum well layers are similar to... Figure 1 The green quantum well layer and the red quantum well layer in the illustrated embodiments have the same structure and film composition, which will not be described again here.

[0062] It is understood that in this embodiment, the epitaxially grown first quantum well layer 101 serves as both an excitation light source and a blue light source; the epitaxially grown second quantum well layer 102 serves as a color transfer layer for the second color, and the epitaxially grown third quantum well layer 302 serves as a color transfer layer for the third color, which can respectively serve as a red light source and a green light source, thereby enabling full-color display of the light-emitting device.

[0063] Reference Figure 2 In some embodiments, the light-emitting device further includes a color filter layer, which comprises a first color resist layer 501, a second color resist layer 502, and a third color resist layer 503. The first color resist layer 501 corresponds to the third light-emitting unit 300, the second color resist layer 502 corresponds to the first light-emitting unit 100, and the third color resist layer 503 corresponds to the second light-emitting unit 200. In other embodiments, the color filter layer may be removed; the embodiments disclosed herein are not limited thereto.

[0064] Figure 3 This is a schematic diagram of the structure of a display device according to some other embodiments of the present disclosure.

[0065] Reference Figure 3The display device includes a light-emitting device and a driving backplate 900. The light-emitting device includes a plurality of first light-emitting units 100, each first light-emitting unit 100 including a first quantum well layer 101 and a second quantum well layer 102. The second quantum well layer 102 is located on the side of the first quantum well layer 101 closest to the light-emitting side of the light-emitting device. The driving backplate 900 is located on the side of the first quantum well layer 101 furthest from the second quantum well layer 102. The first quantum well layer 101 emits light of a first color, and the second quantum well layer 102 emits light of a second color based on the first color light, wherein the wavelength of the first color light is shorter than the wavelength of the second color light.

[0066] In some embodiments of this disclosure, the first color of light is ultraviolet light, and the second color of light is any one of red light, green light, and blue light. That is, in this embodiment, the first quantum well layer 101 is an ultraviolet quantum well layer, and the second quantum well layer 102 is any one of a red light quantum well layer, a green light quantum well layer, and a blue light quantum well layer.

[0067] It is understood that in this embodiment, an ultraviolet quantum well layer is epitaxially grown as an excitation light source; and a second quantum well layer 102 is epitaxially grown as a color conversion layer for the second color, which can be used as a red light source, a green light source, and a blue light source, respectively, thereby realizing full-color display of the light-emitting device.

[0068] Reference Figure 3 In some embodiments, the light-emitting device further includes a color filter layer, which comprises a first color resist layer 501, a second color resist layer 502, and a third color resist layer 503. The first color resist layer 501, for example, corresponds to the second quantum well layer 102 that emits red light, the second color resist layer 502, for example, corresponds to the second quantum well layer 102 that emits green light, and the third color resist layer 503, for example, corresponds to the second quantum well layer 102 that emits blue light. In other embodiments, the color filter layer may be removed, and the embodiments disclosed herein are not limited thereto.

[0069] Figure 4 This is a flowchart of a method for fabricating a light-emitting device according to some embodiments of the present disclosure.

[0070] Reference Figure 4 The fabrication method of the light-emitting device includes steps S1 to S4.

[0071] In step S1, a second quantum well material layer is formed on the substrate.

[0072] In step S2, the second quantum well material layer is patterned to form the second quantum well layer.

[0073] In step S3, a first quantum well material layer is formed on the side of the second quantum well layer away from the substrate.

[0074] In step S4, the first quantum well material layer is patterned to form a first quantum well layer. The side of the second quantum well layer away from the first quantum well layer is the light-emitting side of the light-emitting device. The first quantum well layer is used to emit light of a first color, and the second quantum well layer is used to emit light of a second color based on the first color light. The wavelength of the first color light is shorter than the wavelength of the second color light.

[0075] It should be noted that in this embodiment, both the first quantum well layer and the second quantum well layer are formed through epitaxial growth and patterning. Epitaxial growth of luminescent materials offers many advantages, such as high crystal quality and surface flatness, and precise control over growth conditions and thickness, thereby improving the luminous efficiency and performance of the light-emitting device. Compared to mass transfer processes, epitaxial growth simplifies the process flow and effectively reduces production costs.

[0076] It is understandable that the second quantum well layer can be excited by light of the first color emitted by the first quantum well layer to produce light of the second color. Specifically, the first quantum well layer is electroluminescent, and the second quantum well layer is photoluminescent. In this embodiment, by epitaxially growing a first quantum well layer luminescent material with a shorter wavelength, and then exciting an epitaxially growing second quantum well layer luminescent material with a longer wavelength, pure second-color light can be obtained. This reduces the fabrication cost of the light-emitting device, avoids the challenges of mass transfer, and achieves low-cost, high-pixel-density displays.

[0077] In some embodiments of this disclosure, the method for fabricating the light-emitting device further includes: forming a black matrix layer on the side of the second quantum well layer away from the first quantum well layer, the black matrix layer including a plurality of first openings, the orthogonal projection of the second quantum well layer on the black matrix layer not overlapping with the first openings; forming a first quantum dot layer within the first openings, the first quantum dot layer being used to emit light of a third color based on light of a first color, the wavelength of the third color light being greater than the wavelength of the first color light; and forming a first color resist layer within the first openings, the first color resist layer being located on the side of the first quantum dot layer away from the first quantum well layer.

[0078] It is understood that in this embodiment, the first quantum well layer serves as the excitation light source, and the first quantum dot layer acts as the color conversion layer, emitting light of a third color under the excitation of the first quantum well layer. The first quantum dot layer can be fabricated using a printing process, which is faster than epitaxial growth, thus improving the fabrication efficiency of the light-emitting device.

[0079] In some embodiments of this disclosure, before forming a second quantum well material layer on the substrate, the method for fabricating the light-emitting device further includes: forming a third quantum well material layer on the substrate; and patterning the third quantum well material layer to form a third quantum well layer, wherein the third quantum well layer is used to emit light of a third color based on light of a first color, the wavelength of the third color light being greater than the wavelength of the first color light.

[0080] Understandably, in this embodiment, the first quantum well layer serves as the excitation source, and the third quantum well layer acts as a color conversion layer, emitting light of a third color under the excitation of the first quantum well layer. Since the first, second, and third quantum well layers are all fabricated using epitaxial growth processes and are inorganic layers, their reliability is higher.

[0081] Figures 5a to 5g This is a schematic diagram of the structure of each component in the manufacturing process of a display device according to some embodiments of the present disclosure.

[0082] First refer to Figure 5a A buffer layer 12, an epitaxial layer 13, a second quantum well material layer 1021, and a separation material layer 801 are sequentially grown on a substrate 11. The substrate 11 is, for example, any one of sapphire, silicon carbide (SiC), silicon (Si), and gallium nitride (GaN). The buffer layer 12 is, for example, U-type gallium nitride (U-GaN), i.e., undoped gallium nitride. The structure and film composition of the epitaxial layer 13 are similar to those of the substrate 11. Figure 1 The structure and film composition of the epitaxial layer 13 in the illustrated embodiment are the same, and will not be described again here.

[0083] In some embodiments, in the light emission direction of the light-emitting device, the sum of the thickness of the buffer layer 12 and the thickness of the epitaxial layer 13 is greater than or equal to 1 micrometer and less than or equal to 4.5 micrometers, for example, any value among 1 micrometer, 2 micrometers, 3 micrometers, 4 micrometers, and 4.5 micrometers.

[0084] In some embodiments, a nucleation layer is deposited on the substrate 11 before the buffer layer 12 is formed to provide nucleation sites and improve film quality. The nucleation layer is, for example, a thin layer of low-temperature aluminum nitride.

[0085] Next, refer to Figure 5b ,Will Figure 5a The epitaxial wafer shown is patterned, and part of the separation material layer 801 and the second quantum well material layer 1021 are etched away to form the separation layer 800 and the second quantum well layer 102. The structure and film composition of the second quantum well layer 102 are similar to those of the second quantum well layer 102. Figure 1 The structure and film composition of the green quantum well layer in the illustrated embodiment are the same, and will not be described again here.

[0086] Next, refer to Figure 5c ,existFigure 5b A first quantum well material layer 1011 and a first electrode layer 600 are further grown on the epitaxial wafer shown. In some embodiments, an electron blocking layer is deposited on the first quantum well material layer 1011 before the first electrode layer 600 is grown. It is understood that the electron blocking layer is deposited to prevent electrons from escaping from the first quantum well material layer 1011, reduce electron overflow, and promote efficient recombination of electrons and holes, thereby improving the luminous efficiency and performance of the light-emitting device.

[0087] Next, refer to Figure 5d ,Will Figure 5c The epitaxial wafer shown is patterned by etching away portions of the first electrode layer 600 and the first quantum well material layer 1011 to form multiple first electrodes 601 and first quantum well layers 101. The structure and film composition of the first quantum well layer 101 are similar to those of the first electrode layer 601 and the first quantum well material layer 101. Figure 1 The structure and film composition of the blue quantum well layer in the illustrated embodiment are the same, and will not be described again here.

[0088] Next, refer to Figure 5e ,Will Figure 5d The epitaxial wafer shown is vertically interconnected with the driving backplane 900. Before interconnection with the driving backplane 900, an insulating layer 14 is formed between adjacent light-emitting units.

[0089] Next, refer to Figure 5f Remove the substrate 11 and buffer layer 12, and deposit a second electrode layer 700 on the side of the epitaxial layer 13 away from the second quantum well layer 102.

[0090] Next, refer to Figure 5g A color filter layer is fabricated on the side of the second electrode layer 700 away from the epitaxial layer 13. The black matrix layer 400 includes a plurality of first openings 401, and a first color resist layer 501 is located within the first openings 401. A first quantum dot layer 301 is located within the first openings 401 and between the first color resist layer 501 and the first quantum well layer 101. The first quantum dot layer 301 is, for example, a red quantum dot layer.

[0091] In this embodiment, the first quantum dot layer 301 is formed within the first opening 401 using a printing process, which reduces one patterning process for the first quantum dot layer 301. In other embodiments, the first quantum dot layer 301 can also be fabricated using a photolithography process, and the embodiments disclosed herein are not limited thereto.

[0092] Figure 6 This is a transmission electron microscope cross-sectional view of the second quantum well layer 102 emitting green light based on blue light according to some embodiments of the present disclosure. Figure 7 This is a spectrum of the second quantum well layer 102 emitting green light based on blue light, according to some embodiments of the present disclosure.

[0093] Reference Figure 6 Specifically Figure 5c The image shown is a cross-sectional view of the epitaxial wafer obtained by transmission electron microscopy (TEM). In TEM, HAADF stands for High Angle Annular Dark Field. HAADF utilizes high-angle scattered electrons to generate the image.

[0094] Reference Figure 7 Specifically Figure 5c The spectrum corresponding to the epitaxial wafer is shown below. The horizontal axis represents wavelength in nanometers; the vertical axis represents relative luminescence intensity, specifically using the maximum luminescence intensity of the blue quantum well layer as the standard value. The vertical axis represents the ratio of the quantum well layer's luminescence intensity to the standard value. Figure 7 As shown, in this embodiment, Figure 5c The epitaxial wafer shown can emit green light (the wavelength range of green light is between 500 nanometers and 560 nanometers) from the second quantum well layer 102 by excitation of the blue quantum well layer (the wavelength range of blue light is between 400 nanometers and 500 nanometers).

[0095] Figures 8a to 8i This is a schematic diagram of the structure of each component in the manufacturing process of a display device according to some other embodiments of the present disclosure.

[0096] First refer to Figure 8a A buffer layer 12, an epitaxial layer 13, a third quantum well material layer 3021, and a separation material layer 801 are sequentially grown on a substrate 11. The substrate 11 is, for example, a patterned sapphire substrate (PSS) structure, which enhances optical efficiency. The buffer layer 12 is, for example, U-type gallium nitride (U-GaN), i.e., undoped gallium nitride. The structure and film composition of the epitaxial layer 13 are similar to those of the substrate. Figure 1 The structure and film composition of the epitaxial layer 13 in the illustrated embodiment are the same, and will not be described again here.

[0097] Next, refer to Figure 8b ,Will Figure 8a The epitaxial wafer shown is patterned, and part of the separation material layer 801 and the third quantum well material layer 3021 are etched away to form the separation layer 800 and the third quantum well layer 302. The structure and film composition of the third quantum well layer 302 are similar to those of the previous layer. Figure 1 The structure and film composition of the red quantum well layer in the illustrated embodiment are the same, and will not be described again here.

[0098] Next, refer to Figure 8c ,existFigure 8b A second quantum well material layer 1021 and a separation material layer 801 are further grown on the epitaxial wafer shown.

[0099] Next, refer to Figure 8d ,Will Figure 8c The epitaxial wafer shown is patterned, and part of the separation material layer 801 and the second quantum well material layer 1021 are etched away to form the separation layer 800 and the second quantum well layer 102. The structure and film composition of the second quantum well layer 102 are similar to those of the second quantum well layer 102. Figure 1 The structure and film composition of the green quantum well layer in the illustrated embodiment are the same, and will not be described again here.

[0100] Next, refer to Figure 8e ,exist Figure 8d The first quantum well material layer 1011 and the first electrode layer 600 are further grown on the epitaxial wafer shown.

[0101] Next, refer to Figure 8f ,Will Figure 8e The epitaxial wafer shown is patterned by etching away portions of the first electrode layer 600 and the first quantum well material layer 1011 to form multiple first electrodes 601 and first quantum well layers 101. The structure and film composition of the first quantum well layer 101 are similar to those of the first electrode layer 601 and the first quantum well material layer 101. Figure 1 The structure and film composition of the blue quantum well layer in the illustrated embodiment are the same, and will not be described again here.

[0102] Next, refer to Figure 8g ,Will Figure 8f The epitaxial wafer shown is vertically interconnected with the driving backplane 900. Before interconnection with the driving backplane 900, an insulating layer 14 is formed between adjacent light-emitting units.

[0103] Next, refer to Figure 8h Remove the substrate 11 and buffer layer 12, and deposit a second electrode layer 700 on the side of the epitaxial layer 13 away from the second quantum well layer 102.

[0104] Next, refer to Figure 8i A color filter layer is prepared on the side of the second electrode layer 700 away from the epitaxial layer 13.

[0105] While some embodiments based on the general inventive concept of this disclosure have been illustrated and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the general inventive concept of this disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. A light-emitting device, characterized in that, The light-emitting device includes a plurality of first light-emitting units, wherein the first light-emitting unit includes: The first quantum well layer; and The second quantum well layer is located on the side of the first quantum well layer closest to the light-emitting side of the light-emitting device; The first quantum well layer is used to emit light of a first color, and the second quantum well layer is used to emit light of a second color based on the first color light, wherein the wavelength of the first color light is shorter than the wavelength of the second color light.

2. The light-emitting device according to claim 1, characterized in that, The first color of light is blue light.

3. The light-emitting device according to claim 2, characterized in that, The light-emitting device further includes a plurality of second light-emitting units, wherein the second light-emitting unit includes the first quantum well layer.

4. The light-emitting device according to claim 2, characterized in that, The light-emitting device further includes a plurality of third light-emitting units, the third light-emitting units including: The first quantum well layer; and The first quantum dot layer is located on the side of the first quantum well layer closest to the light-emitting side of the light-emitting device; The first quantum dot layer is used to emit a third color of light based on the blue light, the wavelength of which is greater than the wavelength of the blue light.

5. The light-emitting device according to claim 4, characterized in that, The light-emitting device further includes: A black matrix layer, located on the side of the second quantum well layer away from the first quantum well layer, the black matrix layer including a plurality of first openings, the orthogonal projection of the third light-emitting unit onto the black matrix layer at least partially overlapping the first openings; and The first color resist layer is located inside the first opening; The first quantum dot layer is located within the first opening and between the first color resist layer and the first quantum well layer.

6. The light-emitting device according to claim 5, characterized in that, Along the light emission direction of the light-emitting device, the sum of the thickness of the first quantum dot layer and the thickness of the first color resist layer is approximately equal to the thickness of the black matrix layer.

7. The light-emitting device according to claim 2, characterized in that, The light-emitting device further includes a plurality of third light-emitting units, the third light-emitting units including: The first quantum well layer; and The third quantum well layer is located on the side of the first quantum well layer closest to the light-emitting side of the light-emitting device; The third quantum well layer is used to emit light of a third color based on the blue light, the wavelength of which is greater than that of the blue light.

8. The light-emitting device according to claim 4 or 7, characterized in that, The second color of light is green, and the third color of light is red; or The second color of light is red light, and the third color of light is green light.

9. The light-emitting device according to claim 1, characterized in that, The first color of light is ultraviolet light, and the second color of light is any one of red, green, or blue light.

10. The light-emitting device according to any one of claims 1 to 9, characterized in that, The light-emitting device further includes: A first electrode layer includes a plurality of first electrodes, wherein the first electrodes are located on the side of the first quantum well layer away from the second quantum well layer; and The second electrode layer is located on the side of the second quantum well layer away from the first quantum well layer.

11. The light-emitting device according to any one of claims 1 to 9, characterized in that, The light-emitting device further includes a separation layer, which is located between two adjacent quantum well layers along the light emission direction of the light-emitting device.

12. A display device, characterized in that, The display device includes: The light-emitting device according to any one of claims 1 to 11; and The driving backplate is located on the side of the first quantum well layer away from the second quantum well layer.

13. A method for fabricating a light-emitting device, characterized in that, The method for preparing the light-emitting device includes: A second quantum well material layer is formed on the substrate; The second quantum well material layer is patterned to form the second quantum well layer; A first quantum well material layer is formed on the side of the second quantum well layer away from the substrate; The first quantum well material layer is patterned to form a first quantum well layer. The side of the second quantum well layer away from the first quantum well layer is the light-emitting side of the light-emitting device. The first quantum well layer is used to emit light of a first color, and the second quantum well layer is used to emit light of a second color based on the first color light. The wavelength of the first color light is shorter than the wavelength of the second color light.

14. The method for fabricating a light-emitting device according to claim 13, characterized in that, The method for preparing the light-emitting device further includes: A black matrix layer is formed on the side of the second quantum well layer away from the first quantum well layer. The black matrix layer includes a plurality of first openings. The orthogonal projection of the second quantum well layer onto the black matrix layer does not overlap with the first openings. A first quantum dot layer is formed within the first opening. The first quantum dot layer is used to emit a third color of light based on the first color of light, wherein the wavelength of the third color of light is greater than the wavelength of the first color of light. A first color resist layer is formed within the first opening, and the first color resist layer is located on the side of the first quantum dot layer away from the first quantum well layer.

15. The method for fabricating a light-emitting device according to claim 13, characterized in that, Before forming a second quantum well material layer on the substrate, the fabrication method of the light-emitting device further includes: A third quantum well material layer is formed on the substrate; The third quantum well material layer is patterned to form a third quantum well layer, which is used to emit light of a third color based on the first color light, the wavelength of the third color light being greater than the wavelength of the first color light.

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