Light-emitting device and manufacturing method therefor, light-emitting substrate, and display device

Abstract

A light-emitting device, comprising a plurality of light-emitting units that are sequentially stacked, an adhesive layer, and a conductive pattern. The light-emitting area of a lower light-emitting unit is greater than the light-emitting area of an upper light-emitting unit. Each light-emitting unit comprises a first semiconductor layer, a light-emitting layer, and a second semiconductor layer that are sequentially stacked, and at least a portion of an edge of the first semiconductor layer extends beyond the light-emitting layer. In addition, two adjacent light-emitting units are respectively a first light-emitting unit and a second light-emitting unit, and at least a portion of an edge of the second semiconductor layer of the first light-emitting unit extends beyond the first semiconductor layer of the second light-emitting unit. The adhesive layer is arranged between two adjacent light-emitting units. The conductive pattern is connected to two adjacent light-emitting units. One portion of the conductive pattern is in electrical contact with the edge portion of the second semiconductor layer of the first light-emitting unit extending beyond the first semiconductor layer of the second light-emitting unit, and another portion of the conductive pattern is in electrical contact with the edge portion of the first semiconductor layer of the second light-emitting unit extending beyond the light-emitting layer thereof.

Description

Light emitting device, preparation method thereof, light emitting substrate and display device

[0001] This application claims priority to Chinese Patent Application No. 202410832811.1, filed on June 25, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure relates to the technical field of display, and in particular to a light emitting device, a preparation method thereof, a light emitting substrate and a display device. BACKGROUND

[0003] With the development of light emitting diode technology, display devices using light emitting diodes (LEDs) of sub-millimeter (Mini) level or even micrometer (Micro) level have been widely applied. As a result, not only can the picture contrast of display devices using Micro LEDs or Mini LEDs reach the level of organic light emitting diode (OLED) display devices, but also the display devices can retain the technical advantages of liquid crystal display such as low cost, high brightness and high reliability, thereby improving the display effect of the picture and providing users with a better visual experience. SUMMARY

[0004] In one aspect, a light emitting device is provided. The light emitting device includes a plurality of light emitting units, an adhesive layer and a conductive pattern which are sequentially stacked. A light emitting area of the light emitting unit located at a lower side is greater than a light emitting area of the light emitting unit located at an upper side. The light emitting unit includes a first semiconductor layer, a light emitting layer and a second semiconductor layer which are sequentially stacked, and at least a part of an edge of the first semiconductor layer exceeds the light emitting layer. Moreover, the two adjacent light emitting units are a first light emitting unit and a second light emitting unit, and at least a part of an edge of the second semiconductor layer of the first light emitting unit exceeds the first semiconductor layer of the second light emitting unit.

[0005] The adhesive layer is arranged between the two adjacent light emitting units. The conductive pattern is connected with the two adjacent light emitting units. A part of the conductive pattern is electrically connected with the edge part of the second semiconductor layer of the first light emitting unit which exceeds the first semiconductor layer of the second light emitting unit, and another part of the conductive pattern is electrically connected with the edge part of the first semiconductor layer of the second light emitting unit which exceeds the light emitting layer.

[0006] In some embodiments, the light emitting device further includes a first barrier layer covering the conductive pattern, and a surface of the plurality of light emitting units exposed on a side close to the conductive pattern.

[0007] In some embodiments, the light emitting device further comprises a second barrier layer disposed between the conductive pattern and the light emitting unit. The second barrier layer is provided with a first connecting hole and a second connecting hole. The conductive pattern extends into the first connecting hole and the second connecting hole to electrically contact the first semiconductor layer and the second semiconductor layer, respectively.

[0008] In some embodiments, the light emitting device comprises a first barrier layer comprising a first sub-portion and a second sub-portion. The first sub-portion covers the surface of the plurality of light emitting units exposed on the side close to the conductive pattern. The second sub-portion covers the conductive pattern. The thickness of the first sub-portion is greater than the thickness of the second sub-portion.

[0009] In some embodiments, the conductive pattern comprises a first lap portion, a second lap portion and a first connecting portion. The first lap portion is disposed on the second semiconductor layer. The second lap portion is disposed on the first semiconductor layer. The first connecting portion is disposed between the first lap portion and the second lap portion, and one end of the first connecting portion is connected to the first lap portion and the other end of the first connecting portion is connected to the second lap portion.

[0010] In some embodiments, in a first cross section, the length of the first lap portion and / or the second lap portion is greater than or equal to 1 μm. The first cross section is perpendicular to the plane in which the first semiconductor layer is located and perpendicular to the boundary where the first semiconductor layer contacts the second lap portion. And / or, the distance between the boundary of the first lap portion and the boundary of the second semiconductor layer of the connected first light emitting unit is 0 μm to 5 μm. And / or, the distance between the boundary of the second lap portion and the boundary of the light emitting layer of the connected second light emitting unit is 0 μm to 5 μm.

[0011] In some embodiments, in a first cross section, the length of the first connecting portion in a first direction is 2 μm to 4 μm. The first cross section is perpendicular to the plane in which the first semiconductor layer is located and perpendicular to the boundary where the first semiconductor layer contacts the second lap portion. The first direction is parallel to the plane in which the first semiconductor layer is located. And / or, the included angle between the first connecting portion and the second semiconductor layer is 60° to 80°.

[0012] In some embodiments, the current values corresponding to the peak values of the light emitting efficiencies of at least two of the light emitting units are not equal.

[0013] In some embodiments, the light emitting device comprises two of the light emitting units, and the ratio of the current value corresponding to the peak value of the light emitting efficiency of one of the two light emitting units to the current value corresponding to the peak value of the light emitting efficiency of the other of the two light emitting units is 5 to 20.

[0014] In some embodiments, the peak of the light emitting efficiency of the light emitting unit corresponds to a current value less than or equal to 0.5 mA.

[0015] In some embodiments, the ratio of the light emitting area of the second light emitting unit to the light emitting area of the first light emitting unit is 10% to 80%.

[0016] In some embodiments, the light emitting device further comprises a first electrode disposed on the upper surface of the uppermost second semiconductor layer.

[0017] In some embodiments, the light emitting device further comprises a second electrode disposed on the upper surface of the edge portion of the lowermost first semiconductor layer beyond the light emitting layer.

[0018] In some embodiments, the shape of the orthographic projection of the first semiconductor layer on a reference plane is a rectangle, and the reference plane is the plane on which the lowermost first semiconductor layer is located. Among the lowermost light emitting units, the light emitting layer exposes a corner region of the first semiconductor layer, and the second electrode is disposed on the corner region.

[0019] In some embodiments, in the orthographic projection on the reference plane, the second electrode is located on one side of the first semiconductor layer of the second light emitting unit along a second direction. The conductive pattern covers the first boundary of the corresponding first semiconductor layer of the second light emitting unit, the first boundary is perpendicular to the second direction, and is located between the first electrode and the second electrode.

[0020] In some embodiments, in the orthographic projection on the reference plane, the second electrode is located on the extension line of the second boundary of the first semiconductor layer of the second light emitting unit. The conductive pattern covers the second boundary of the corresponding first semiconductor layer of the second light emitting unit.

[0021] In some embodiments, the light emitting device further comprises a conductive substrate, a conductive bonding layer, a first electrode and a second electrode. The conductive substrate is disposed on the upper side of the plurality of light emitting units. The conductive bonding layer is disposed between the conductive substrate and the plurality of light emitting units. The first electrode is disposed on the side of the first semiconductor layer farthest from the conductive substrate away from the conductive substrate. The second electrode is disposed on the side of the conductive substrate away from the plurality of light emitting units.

[0022] In another aspect, a light emitting substrate is provided. The light emitting substrate comprises a driving backplane and a light emitting device as described in any of the above embodiments, and the light emitting device is connected to the driving backplane.

[0023] In yet another aspect, a display device is provided. The display device comprises a light emitting substrate as described in the above embodiments.

[0024] In still another aspect, a method for manufacturing a light emitting device is provided. The method includes forming a plurality of light emitting units and an adhesive layer. The plurality of light emitting units are sequentially stacked, and a light emitting area of a lower light emitting unit is larger than a light emitting area of an upper light emitting unit. The light emitting units include sequentially stacked first, second, and light emitting layers, at least a portion of an edge of the first semiconductor layer extending beyond the light emitting layer. The light emitting units include a first light emitting unit and a second light emitting unit, at least a portion of an edge of the second semiconductor layer of the first light emitting unit extending beyond the first semiconductor layer of the second light emitting unit. The adhesive layer is disposed between the first and second light emitting units.

[0025] A conductive pattern is formed. The conductive pattern is connected to the first and second light emitting units. A portion of the conductive pattern is electrically connected to the edge of the second semiconductor layer of the first light emitting unit extending beyond the first semiconductor layer of the second light emitting unit, and another portion of the conductive pattern is electrically connected to the edge of the first semiconductor layer of the second light emitting unit extending beyond the light emitting layer. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the present disclosure, the following will briefly introduce the drawings needed to be used in some embodiments of the present disclosure. Obviously, the drawings described in the following description are only some drawings of the embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art according to these drawings. In addition, the drawings described in the following description can be regarded as schematic diagrams, and are not limited to the actual size, actual process, actual time sequence, etc. of the products involved in the embodiments of the present disclosure.

[0027] FIG. 1 is a structural diagram of a display device according to some embodiments;

[0028] FIG. 2 is a structural diagram of another display device according to some embodiments;

[0029] FIG. 3 is a sectional view along the section line A-A in FIG. 1;

[0030] FIG. 4 is another sectional view along the section line A-A in FIG. 1;

[0031] FIG. 5 is a top view of a light emitting device according to some embodiments;

[0032] FIG. 6 is a sectional view along the section line B-B in FIG. 5;

[0033] FIG. 7 is a structural diagram of a light emitting device according to some embodiments;

[0034] FIG. 8 is a structural diagram of another light emitting device according to some embodiments;

[0035] FIG. 9 is a top view of another light emitting device according to some embodiments;

[0036] FIG. 10 is a structural diagram of still another light emitting device according to some embodiments;

[0037] FIG. 11 is a structural diagram of yet another light emitting device according to some embodiments;

[0038] FIG. 12 is a graph of luminous efficiency versus current for three light emitting devices according to some embodiments;

[0039] FIG. 13 is a graph of luminous efficiency versus current for two light emitting units in the same light emitting device according to some embodiments;

[0040] FIG. 14 is a graph of current size of luminous efficiency peak versus luminous efficiency peak for a light emitting device according to some embodiments;

[0041] FIG. 15 is a top view of still another light emitting device according to some embodiments;

[0042] FIG. 16 is a top view of yet another light emitting device according to some embodiments;

[0043] FIG. 17 is a top view of still another light emitting device according to some embodiments;

[0044] FIG. 18 is a structural diagram of yet another light emitting device according to some embodiments;

[0045] FIG. 19 is a flowchart of a method of fabricating a light emitting device according to some embodiments;

[0046] FIG. 20 is a flowchart of a method of fabricating a light emitting device according to some embodiments;

[0047] FIGS. 21 to 24 are process diagrams of a method of fabricating a light emitting device of a vertical package structure according to some embodiments;

[0048] FIGS. 25 to 29 are process diagrams of a method of fabricating a light emitting device of a flip-chip package structure according to some embodiments;

[0049] FIG. 30 is a flowchart of a method of fabricating a light emitting device according to some embodiments;

[0050] FIG. 31 is a process diagram of a method of fabricating a light emitting device of a vertical package structure according to some embodiments;

[0051] FIG. 32 is a process diagram of a method of fabricating a light emitting device of a flip-chip package structure according to some embodiments;

[0052] FIG. 33 is a flowchart of a method of fabricating a light emitting device according to some embodiments;

[0053] FIG. 34 is a fabrication step diagram of a fabrication method of a light emitting device of a vertical mount structure, according to some embodiments;

[0054] FIG. 35 is a fabrication step diagram of a fabrication method of a light emitting device of a flip chip structure, according to some embodiments;

[0055] FIG. 36 is a fabrication step diagram of a fabrication method of a light emitting device of a vertical mount structure, according to some embodiments;

[0056] FIG. 37 is a fabrication step diagram of a fabrication method of a light emitting device of a flip chip structure, according to some embodiments;

[0057] FIG. 38 is a fabrication step diagram of a fabrication method of a light emitting device of a vertical mount structure, according to some embodiments;

[0058] FIG. 39 is a flowchart of a fabrication method of a light emitting device, according to some embodiments;

[0059] FIG. 40 is a fabrication step diagram of a fabrication method of a light emitting device of a vertical mount structure, according to some embodiments;

[0060] FIG. 41 is a fabrication step diagram of a fabrication method of a light emitting device of a vertical mount structure, according to some embodiments;

[0061] FIG. 42 is a flowchart of a fabrication method of a light emitting device, according to some embodiments;

[0062] FIG. 43 is a fabrication step diagram of a fabrication method of a light emitting device of a flip chip structure, according to some embodiments. DETAILED DESCRIPTION

[0063] The technical solutions in some embodiments of the present disclosure will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present disclosure.

[0064] Unless the context clearly requires otherwise, throughout the description and the claims, the term "comprise," and variations thereof (e.g., "comprises" and "comprising"), will be construed to be inclusive in a manner consistent with the term's plain meaning, namely, "including but not limited to." In describing the description, the terms "one embodiment," "some embodiments," "exemplary embodiments," "example," "specific example" or "some examples," and the like, mean that a particular feature, structure, material, or characteristic is included in at least one embodiment or example of the disclosure, but that it can not be included in other embodiments or examples. The illustrative appearance of the foregoing terms in various places in the description are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0065] Hereinafter, the terms "first", "second", etc. are used only for the purpose of description and should not be construed as indicating or implying relative importance or implying the number of the technical features indicated. Thus, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the disclosure, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0066] In describing some embodiments, "coupled" and "connected," and variations thereof, can be used. The term "connected" should be interpreted broadly, for example, "connected" can be fixedly connected, or detachably connected, or integrated; can be directly connected, or indirectly connected through an intermediate medium. The term "coupled" indicates, for example, that two or more components have direct physical contact or electrical contact. The term "coupled" or "communicatively coupled" can also mean that two or more components do not have direct contact with each other, but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the content herein.

[0067] "A, B, and C at least one of" has the same meaning as "at least one of A, B, or C", and includes the following combinations of A, B, and C: only A, only B, only C, a combination of A and B, a combination of A and C, a combination of B and C, and a combination of A, B, and C.

[0068] "A and / or B" includes the following three combinations: only A, only B, and a combination of A and B.

[0069] The use of "adapted to" or "configured to" herein is meant as open and inclusive language that does not foreclose devices adapted to or configured to perform additional tasks or steps. Conjunctive language such as the

[0070] Additionally, the use of "based on" is meant to be open and inclusive, in that a process, step, calculation, or other action "based on" one or more recited conditions or values may, in practice, be based on additional conditions or values beyond those recited.

[0071] As used herein, "about," "substantially," or "approximately" in reference to a given value typically includes within an acceptable range of variation for the given value, such as a range of variation that a person of ordinary skill in the art would consider acceptable when measuring the given value under similar circumstances.

[0072] As used herein, "parallel," "perpendicular," "equal" includes the recited condition and conditions that are approximately the recited condition, the approximation being within an acceptable range of variation, as determined by a person of ordinary skill in the art considering the measurement in question and the error associated with measuring a particular quantity (i.e., the limitations of the measurement system). For example, "equal" includes absolute equality and approximate equality, where the acceptable range of variation for approximate equality may be, for example, a difference between the two of less than or equal to 5% of either.

[0073] It will be understood that when a layer or element is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening layers can also be present.

[0074] Exemplary embodiments are described herein with reference to cross-sectional and / or plan view illustrations that are idealized examples. In the interest of clarity, not all of the circular features can be shown in the drawings. It will be understood that in the drawings, the thickness of layers and regions are exaggerated for clarity, and that the dimensions of the layers and regions shown in the drawings are intended to illustrate, but not limit, exemplary embodiments. As such, exemplary embodiments should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result from, for example, manufacturing. For example, an etched region illustrated as a rectangle will typically have rounded features. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region of a device and are not intended to limit the scope of exemplary embodiments.

[0075] As shown in FIGS. 1 and 2, some embodiments of the present disclosure provide a display device 1000, which can be any device that displays images whether in motion (e.g., video) or stationary (e.g., a still image), and whether textual or pictorial.

[0076] Exemplarily, referring to FIG. 1 and FIG. 2, the display device 1000 can be any product or component having a display function, such as a television, a notebook computer, a tablet computer, a vehicle display, a flight display, a portable display product (for example, a mobile phone), a wearable device (for example, a watch), a camera, a camcorder, a projector, a calculator, a wireless device, a personal digital assistant (PDA), a clock, a global positioning system (GPS) receiver / navigator, a virtual reality (VR) device, an augmented reality (AR) device, an electronic billboard or sign, and the like.

[0077] For example, as shown in FIG. 1, the display device 1000 can be a portable display product; for example, the display device 1000 can be a mobile phone as shown in FIG. 1. For another example, referring to FIG. 2, the display device 1000 can be a wearable device; for example, the display device 1000 can be a watch as shown in FIG. 2.

[0078] It should be noted that, according to different application scenarios, the display device 1000 can be a flat display device, a curved display device, a folding display device, and the like, and the shape of the display surface of the display device 1000 can be any one of a circle, an ellipse, a polygon, or an irregular figure, and the embodiments of the present disclosure are not limited thereto.

[0079] In the following, some embodiments of the present disclosure will be schematically described by taking the display device 1000 as the mobile phone shown in FIG. 1 as an example, but the embodiments of the present disclosure are not limited thereto, and any other display device can also be considered as long as the same technical idea is applied.

[0080] In some embodiments, referring to FIG. 3 and FIG. 4, the display device 1000 includes a light-emitting substrate 100, the light-emitting substrate 100 has opposite light-emitting sides and non-light-emitting sides, the light-emitting side refers to a side (the upper side of the light-emitting substrate 100 in FIG. 3 and FIG. 4) of the light-emitting substrate 100 capable of emitting light, and the non-light-emitting side refers to the other side (the lower side of the light-emitting substrate 100 in FIG. 3 and FIG. 4) opposite to the light-emitting side.

[0081] Exemplarily, referring to FIG. 3 and FIG. 4, the display device 1000 further includes a driving circuit board 200, a housing 300, and a cover plate 400, the cover plate 400 is arranged on the light-emitting side of the light-emitting substrate 100 to protect the light-emitting substrate 100; the driving circuit board 200 is connected with the light-emitting substrate 100 to provide a light-emitting signal to the light-emitting substrate 100.

[0082] The shell 300 can be a box-shaped structure with an opening, the light-emitting substrate 100 and the driving circuit board 200 can be arranged in the shell 300, the cover plate 400 is arranged on the light-emitting side of the light-emitting substrate 100 and located at the opening of the shell 300.

[0083] It should be understood that the display device 1000 described above can be a liquid crystal display (LCD) or a micro light emitting display (MLED), and the embodiments of the present disclosure do not make specific limitations thereon.

[0084] In some embodiments, as shown in FIG. 3, the display device 1000 can be a liquid crystal display device. At this time, the light-emitting substrate 100 described above can serve as a backlight source in the liquid crystal display device, for providing backlight for the display panel 500, and the display panel 500 can adjust the light intensity (gray scale) passing through the display panel 500, thereby realizing image display.

[0085] Exemplarily, referring to FIG. 3, the display device 1000 further includes a display panel 500 arranged on the light-emitting side of the light-emitting substrate 100. The display panel 500 can be, for example, a liquid crystal display panel.

[0086] The light-emitting substrate 100 can directly emit white light, the white light is emitted to the display panel 500 after uniform light processing, the display panel 500 adjusts the light intensity (gray scale) passing through the display panel 500 and performs color conversion, thereby realizing full-color display.

[0087] Alternatively, the light-emitting substrate 100 can emit light of other colors (for example, blue), and then emit to the display panel 500 after color conversion and uniform light processing, the display panel 500 adjusts the light intensity (gray scale) passing through the display panel 500, thereby realizing full-color display.

[0088] Alternatively, the light-emitting substrate 100 can emit light of multiple colors (for example, red, blue and green), and then emit to the display panel 500 after uniform light processing, the display panel 500 adjusts the light intensity (gray scale) passing through the display panel 500, thereby realizing full-color display.

[0089] In other embodiments, referring to FIG. 4, the display device 1000 can be a micro light emitting display device. At this time, the light-emitting substrate 100 described above can serve as a display panel of the micro light emitting display device, and directly perform display.

[0090] The light-emitting substrate 100 can directly emit white light or light of other colors (e.g., blue) and achieve full-color display through color conversion. Alternatively, the light-emitting substrate 100 can directly emit light of multiple colors (e.g., red, blue, and green) to achieve full-color display.

[0091] In the following, some embodiments of the present disclosure are exemplarily described by taking the display device 1000 as a micro light-emitting display device, but the embodiments of the present disclosure are not limited thereto, and any other display device can also be considered as long as the same technical idea is applied.

[0092] In some embodiments, referring to FIGS. 3 and 4, the light-emitting substrate 100 includes a driving backplate 10 and a light-emitting device 20 disposed on the driving backplate 10 and connected with the driving backplate 10 to receive a first power signal and a second power signal to drive the light-emitting device 20 to emit light.

[0093] It should be noted that the first power signal and the second power signal are used to provide a power voltage to the light-emitting device 20, for example, the first power signal is connected to the positive pole of a power supply, and the second power signal is connected to the negative pole of the power supply.

[0094] The orthographic projection of the light-emitting device 20 on the driving backplate 10 can be any one of a circle, an ellipse, and a polygon, and the embodiments of the present disclosure are not limited thereto. Moreover, the light-emitting device 20 can include a Micro LED and / or a Mini LED. For example, the radial length of the orthographic projection of the Micro LED on the driving backplate 10 is less than 50 μm, such as 10 μm to 50 μm. For another example, the radial length of the orthographic projection of the Mini LED on the driving backplate 10 is 50 μm to 150 μm, such as 80 μm to 120 μm.

[0095] It should be noted that the radial length of the orthographic projection refers to the length of a connecting line segment connecting two points on the boundary of the orthographic projection and passing through the geometric center of the orthographic projection. For example, when the orthographic projection is a quadrilateral, the radial length includes the lengths of the side and the diagonal. For example, when the orthographic projection is a circle, the radial length is the diameter.

[0096] In some embodiments, referring to FIGS. 3 and 4, the light-emitting substrate 100 further includes an encapsulation layer 600 covering the light-emitting device 20 to protect the light-emitting device 20. The material of the encapsulation layer 600 includes transparent silicone.

[0097] In some embodiments, referring to FIGS. 5 and 6, the light emitting device 20 includes a plurality of light emitting units 210 in series, and each light emitting unit 210 includes a first semiconductor layer 21, a light emitting layer 22, and a second semiconductor layer 23, which are sequentially stacked, i.e., the light emitting layer 22 is disposed between the first semiconductor layer 21 and the second semiconductor layer 23. At this time, the area of the first semiconductor layer 21, the light emitting layer 22, and the second semiconductor layer 23 that overlap with each other is the light emitting area of one light emitting unit 210. In this case, the light emitting device 20 can be driven by a high-voltage transmission driving signal, thereby forming a high-voltage driven light emitting device 20 to reduce the driving current and power consumption.

[0098] It should be noted that the shape of the orthographic projection of the light emitting unit 210 on the driving backplate 10 can be any one of a circle, an ellipse, and a polygon, and the embodiments of the present disclosure are not limited thereto.

[0099] In the light emitting unit 210, one of the first semiconductor layer 21 and the second semiconductor layer 23 is a P-type semiconductor layer, and the other is an N-type semiconductor layer. The light emitting layer 22 can be, for example, a multiple quantum well (MQW) layer. At this time, when a voltage is applied to the light emitting unit 210, the electrons in the N-type semiconductor layer migrate to the light emitting layer 22 and enter the light emitting layer 22. The holes in the P-type semiconductor layer also migrate to the light emitting layer 22 and enter the light emitting layer 22. The electrons and the holes that enter the light emitting layer 22 recombine to generate spontaneous emission light.

[0100] In the following, the first semiconductor layer 21 is taken as an N-type semiconductor layer, and the second semiconductor layer 23 is taken as a P-type semiconductor layer for example, but the embodiments of the present disclosure are not limited thereto, and the first semiconductor layer 21 can also be a P-type semiconductor layer and the second semiconductor layer 23 can also be an N-type semiconductor layer, as long as the same technical idea is applied.

[0101] In some embodiments, referring to FIGS. 4, 5, and 6, the plurality of light emitting units 210 are sequentially stacked in a direction perpendicular to the driving backplate 10, so that the orthographic projections of the plurality of light emitting units 210 on the driving backplate 10 at least partially overlap, and can jointly occupy a part of the area of the driving backplate 10, thereby compressing the area of the light emitting device 20 on the driving backplate 10, facilitating the arrangement density of the light emitting device 20 on the driving backplate 10, and further improving the resolution of the display device 1000.

[0102] Here, the shapes of the outer contours of the orthographic projections of the plurality of light emitting units 210 on the driving backplate 10 can be the same, which facilitates the size control between different light emitting units 210 and can reduce the process difficulty.

[0103] In the related art, multiple light emitting units are connected by a transparent conductive layer (such as heavily doped N-type gallium nitride) formed by a growth process, or are connected by a bonding process through a transparent conductive layer (indium tin oxide or indium gallium zinc oxide). The production efficiency and yield are low. The inventors have found that, in the process of forming the transparent conductive layer by the two processes, the reliability of the connection and the conductive performance of the transparent conductive layer need to be considered, the process is uncontrollable and difficult, and the production efficiency and yield are reduced.

[0104] Based on this, referring to FIGS. 5 and 6, some embodiments of the present disclosure provide a light emitting device 20 further comprising an adhesive layer 24 and a conductive pattern 25.

[0105] The material of the adhesive layer 24 described above can include transparent benzocyclobutene. The material of the conductive pattern 25 described above can include a metal material, for example, the material of the conductive pattern 25 includes at least one of gold, silver, aluminum, tungsten, nickel, copper, and iron.

[0106] The adhesive layer 24 is arranged between the two adjacent light emitting units 210 to adhere and fix the two light emitting units 210, and the conductive pattern 25 is connected with the two adjacent light emitting units 210 to make the multiple light emitting units 210 in series.

[0107] For example, referring to FIGS. 6 and 10, in the multiple light emitting units 210 arranged in sequence, the light emitting area of the light emitting unit 210 on the lower side is greater than the light emitting area of the light emitting unit 210 on the upper side, and at least part of the edge of the first semiconductor layer 21 exceeds the light emitting layer 22.

[0108] For the convenience of description, the two adjacent light emitting units 210 are respectively a first light emitting unit 211 and a second light emitting unit 212, the first semiconductor layer 21 of the first light emitting unit 211 and the second light emitting unit 212 are respectively marked as 21-1 and 21-2, the light emitting layer 22 of the first light emitting unit 211 and the second light emitting unit 212 are respectively marked as 22-1 and 22-2, and the second semiconductor layer 23 of the first light emitting unit 211 and the second light emitting unit 212 are respectively marked as 23-1 and 23-2.

[0109] At this time, at least part of the edge of the second semiconductor layer 23-1 of the first light emitting unit 211 exceeds the first semiconductor layer 21-2 of the second light emitting unit 212.

[0110] On this basis, as shown in FIGS. 5, 6, 9 and 10, part of the conductive pattern 25 is in electrical contact with the edge part of the second semiconductor layer 23-1 of the first light emitting unit 211 exceeding the first semiconductor layer 21-2 of the second light emitting unit 212, and the other part is in electrical contact with the edge part of the first semiconductor layer 21-2 of the second light emitting unit 212 exceeding the light emitting layer 22-2.

[0111] In this case, the plurality of light emitting units 210 arranged in sequence can be fixed by the adhesive layer 24 through the adhesive process, and electrically connected by the conductive pattern 25 through the deposition and / or patterning process. In this case, the formation of the adhesive layer 24 does not need to consider the conductive performance, and only needs to make the plurality of light emitting units 210 form a reliable connection through the adhesive process, which has low process difficulty. And the formation of the conductive pattern 25 does not need to consider the reliability of the connection of the plurality of light emitting units 210, and only needs to make the plurality of light emitting units 210 form a good conductive connection through the deposition and / or patterning process, which has low process difficulty. From the above, compared with the related art, the preparation process of the light emitting device 20 provided by the embodiments of the present disclosure has low process difficulty, and the process is controlled for a single property (connection reliability or conductive performance), which has high controllability and is beneficial to improve production efficiency and yield.

[0112] In the following, some embodiments of the present disclosure will be exemplarily described by taking the light emitting device 20 including two stacked light emitting units 210, and the two stacked light emitting units 210 being the first light emitting unit 211 and the second light emitting unit 212 as an example, but the embodiments of the present disclosure are not limited thereto, and can also consider including 3, 4 or more light emitting units 210 as long as the same technical idea is applied.

[0113] In some embodiments, as shown in FIGS. 7, 8, 10 and 11, the light emitting device 20 further includes a first barrier layer 26 covering the conductive pattern 25 and the surface of the plurality of light emitting units 210 exposed on the side close to the conductive pattern 25, so as to play an insulating protection role and be beneficial to improve the service life of the light emitting device 20.

[0114] It should be noted that the material of the first barrier layer 26 includes an inorganic insulating material. Exemplarily, the material of the first barrier layer 26 includes silicon oxide and / or silicon nitride. For example, the material of the first barrier layer 26 includes silicon dioxide.

[0115] In some embodiments, as shown in FIGS. 7 and 10, the conductive pattern 25 is in contact with the sidewall of the first semiconductor layer 21-2 of the second light emitting unit 212, that is, there is no other film layer between the conductive pattern 25 and the sidewall of the first semiconductor layer 21-2 of the second light emitting unit 212.

[0116] In some other embodiments, as shown in FIG. 8 and FIG. 11, the light emitting device 20 further comprises a second barrier layer 27, which is disposed between the conductive pattern 25 and the light emitting units 210. The second barrier layer 27 is provided with a first connecting hole 271 and a second connecting hole 272, and the conductive pattern 25 extends into the first connecting hole 271 and the second connecting hole 272 to electrically contact the first semiconductor layer 21-2 of the second light emitting unit 212 and the second semiconductor layer 23-1 of the first light emitting unit 211, respectively.

[0117] It should be noted that the first connecting hole 271 and the second connecting hole 272 can be in the shape of a strip or a frame, and the embodiments of the present disclosure are not limited thereto.

[0118] In this case, the conductive pattern 25 is not in contact with the sidewall of the first semiconductor layer 21-2 of the second light emitting unit 212, and is formed on the second barrier layer 27. Since the sidewall of the first semiconductor layer 21-2 of the second light emitting unit 212 has defects, the conductive pattern 25 is formed on the second barrier layer 27, and has good adhesion, which is conducive to the formation of the conductive pattern 25, and the conductivity of the conductive pattern 25 and the first semiconductor layer 21-2 of the second light emitting unit 212 is high.

[0119] It should be noted that the material of the second barrier layer 27 includes an inorganic insulating material. Exemplarily, the material of the second barrier layer 27 includes silicon oxide and / or silicon nitride. For example, the material of the second barrier layer 27 includes silicon dioxide.

[0120] On this basis, as shown in FIG. 8 and FIG. 11, the first barrier layer 26 can include a first sub-portion 261 and a second sub-portion 262, for example. The first sub-portion 261 covers the exposed surface of the plurality of light emitting units 210 on the side close to the conductive pattern 25, and the second sub-portion 262 covers the conductive pattern 25. Moreover, the thickness of the first sub-portion 261 is greater than the thickness of the second sub-portion 262.

[0121] Here, as shown in FIG. 8, the first sub-portion 261 can include a first sub-layer 2611 and a second sub-layer 2612. The first sub-layer 2611 covers the exposed surface of the plurality of light emitting units 210 on the side close to the conductive pattern 25, and the second sub-layer 2612 is disposed on the side of the first sub-layer 2611 away from the light emitting units 210. Moreover, the first sub-layer 2611 can be the same material as the second barrier layer 27, and the first sub-layer 2611 and the second barrier layer 27 are prepared in the same process step. The second sub-layer 2612 can be prepared in the same process step as the second sub-portion 262, which can simplify the process flow and improve production efficiency.

[0122] The thickness of the first sub-section 261 can be 2 μm to 4 μm. For example, the thickness of the first sub-section 261 can be any one of 2 μm, 2.2 μm, 2.4 μm, 2.5 μm, 2.7 μm, 3 μm, 3.3 μm, 3.5 μm, 3.6 μm, 3.8 μm and 4 μm.

[0123] The thickness of the second sub-section 262 can be 1 μm to 2 μm. For example, the thickness of the second sub-section 262 can be any one of 1 μm, 1.2 μm, 1.4 μm, 1.5 μm, 1.7 μm, 1.8 μm and 2 μm.

[0124] In some embodiments, referring to FIG. 6, the conductive pattern 25 includes a first bonding section 251, a second bonding section 252 and a first connecting section 253, the first bonding section 251 is disposed on the second semiconductor layer 23-1 of the first light emitting unit 211, the second bonding section 252 is disposed on the first semiconductor layer 21-2 of the second light emitting unit 212, the first connecting section 253 is disposed between the first bonding section 251 and the second bonding section 252, and one end of the first connecting section 253 is connected with the first bonding section 251 and the other end of the first connecting section 253 is connected with the second bonding section 252.

[0125] On this basis, as shown in FIG. 6, on the first cross section, the length D1 of the first bonding section 251 and / or the second bonding section 252 is greater than or equal to 1 μm, so that the first bonding section 251 and the corresponding second semiconductor layer 23-1 can form a good conductive contact, and the second bonding section 252 and the corresponding first semiconductor layer 21-2 can form a good conductive contact. The first cross section is perpendicular to the plane where the first semiconductor layer 21-2 is located, and is perpendicular to the boundary where the first semiconductor layer 21-2 and the second bonding section 252 are in contact.

[0126] Here, in the process of preparing the first bonding section 251 and the second bonding section 252, the design value of the length of the first bonding section 251 and the second bonding section 252 can be greater than or equal to 1 μm in combination with the process precision of the etching process and the process precision of the bonding process. For example, the process precision of the etching process is ±1 μm, and the process precision of the bonding process is ±2 μm. At this time, the design value of the length of the first bonding section 251 and the second bonding section 252 can be greater than or equal to 4 μm.

[0127] The distance D2 between the boundary of the first bonding section 251 and the boundary of the second semiconductor layer 23 of the connected first light emitting unit 211 is 0 μm to 5 μm, so as to avoid the problem that the first bonding section 251 is connected with the first semiconductor layer 21 under the corresponding second semiconductor layer 23.

[0128] The distance D3 between the boundary of the second connecting portion 252 and the boundary of the light-emitting layer 22 of the connected second light-emitting unit 212 is 0 μm to 5 μm, so as to avoid the problem of short circuit caused by the connection of the second connecting portion 252 and the second semiconductor layer 23 on the upper side of the corresponding first semiconductor layer 21.

[0129] In some embodiments, referring to FIG. 6, the included angle between the first connecting portion 253 and the second semiconductor layer 23-1 of the first light-emitting unit 211 is 60° to 80°. For example, the included angle between the first connecting portion 253 and the second semiconductor layer 23-1 of the first light-emitting unit 211 is any one of 60°, 62°, 65°, 67°, 70°, 73°, 75°, 78° and 80°, and the embodiments of the present disclosure are not limited thereto.

[0130] On this basis, as shown in FIG. 6, on the first cross section, the length D4 of the first connecting portion 253 can be 2 μm to 4 μm along the first direction X, and the first direction X is parallel to the plane where the first semiconductor layer 21-2 is located. For example, the length D4 of the first connecting portion 253 can be any one of 2 μm, 2.2 μm, 2.4 μm, 2.5 μm, 2.7 μm, 3 μm, 3.3 μm, 3.5 μm, 3.6 μm, 3.8 μm and 4 μm.

[0131] FIG. 12 is a diagram of the relationship between the luminous efficiency and the current of three light-emitting devices according to some embodiments. In FIG. 12, the luminous efficiency is optimized in different current intervals for the light-emitting device A, the light-emitting device B and the light-emitting device C. Among them, the types of the light-emitting units 210 of the same light-emitting device 20 are the same, and the types of the light-emitting units 210 of different light-emitting devices 20 are different, that is, the types of the light-emitting units 210 included in the light-emitting device A, the light-emitting device B and the light-emitting device C are different.

[0132] It should be noted that the same type means that the current values corresponding to the peak values of the luminous efficiency of the light-emitting units 210 are approximately equal, and the different type is the opposite.

[0133] As can be seen from FIG. 12, the current values corresponding to the peak values of the luminous efficiency of the light-emitting device A, the light-emitting device B and the light-emitting device C are very different, and any one of the light-emitting devices 20 cannot make the luminous efficiency of the light-emitting device 20 be high at the entire gray scale.

[0134] FIG. 13 is a diagram of the relationship between the luminous efficiency and the current of two light-emitting units in the same light-emitting device according to some embodiments. In FIG. 13, the luminous efficiency in the working current interval at the entire gray scale is optimized for the light-emitting unit D and the light-emitting unit E in the same light-emitting device 20. Among them, the types of the light-emitting unit D and the light-emitting unit E are different.

[0135] As shown in FIG. 13, the peak values of the luminous efficiencies of the light emitting units D and E correspond to different current values, the luminous efficiencies of the light emitting units D and E compensate for each other, and the luminous efficiency of the light emitting device 20 is relatively high in a relatively large current range, and the luminous efficiency changes relatively gently.

[0136] Based on this, referring to FIGS. 11 and 13, the light emitting device 20 provided by some embodiments of the present disclosure is configured such that the peak values of the luminous efficiencies of the at least two light emitting units 210 correspond to different current values. In this way, the two light emitting units 210 whose peak values of the luminous efficiencies correspond to different current values can be compensated by differentiation, so that the luminous efficiency of the light emitting device 20 is relatively high in the entire gray scale, and the luminous efficiency changes relatively gently in the entire gray scale.

[0137] For example, the two light emitting units 210 whose peak values of the luminous efficiencies correspond to different current values have relatively low luminous efficiency in low gray scale and relatively high luminous efficiency in high gray scale, so that the luminous efficiency of the light emitting device 20 is relatively stable in the entire gray scale, thereby reducing the difficulty of algorithm correction.

[0138] In addition, the current value corresponding to the peak value of the luminous efficiency of the light emitting unit 210 is less than or equal to 0.5 mA, so as to avoid that the luminous efficiency of the light emitting device 20 is very low when the current is relatively small.

[0139] In some embodiments, as shown in FIGS. 6 and 13, the light emitting device 20 includes two light emitting units 210, and the current value at the intersection of the curves of the luminous efficiency and the current of one of the two light emitting units 210 and the curves of the luminous efficiency and the current of the other of the two light emitting units 210 is a first target current value.

[0140] In addition, the minimum current value of the light emitting device 20 in the entire gray scale is a first preset current value, the maximum current value of the light emitting device 20 is a second preset current value, and the difference between the second preset current value and the first preset current value is a first difference value. The difference between the first target current value and the first preset current value is a second difference value, and the ratio of the second difference value to the first difference value is 1 / 2-2 / 3, so that the compensation effect of the two light emitting units 210 is relatively uniform in the entire gray scale, and the luminous efficiency changes relatively gently.

[0141] In some embodiments, as shown in FIG. 6 and FIG. 13, the light emitting device 20 includes two light emitting units 210, and the ratio of the current value corresponding to the peak of the light emitting efficiency of one of the two light emitting units 210 to the current value corresponding to the peak of the light emitting efficiency of the other one of the two light emitting units 210 is 5-20. For example, the current value corresponding to the peak of the light emitting efficiency of one of the two light emitting units 210 is 0.03 mA, and the current value corresponding to the peak of the light emitting efficiency of the other one of the two light emitting units 210 is 0.3 mA. In this case, through compensation of the light emitting efficiency of different light emitting units 210, the light emitting device 20 can have high light emitting efficiency and gentle change in the entire gray scale.

[0142] It should be understood that the current value corresponding to the peak of the light emitting efficiency of the light emitting unit 210 can be adjusted according to the doping concentration of the first semiconductor layer 21, the doping concentration of the second semiconductor layer 23, and the thickness of the light emitting layer 22, and can also be adjusted according to the light emitting area of the light emitting unit 210, and the embodiments of the present disclosure are not limited thereto.

[0143] FIG. 14 is a comparison diagram of the current value of the peak of the light emitting efficiency and the peak of the light emitting efficiency of the light emitting device under different light emitting areas according to some embodiments. As shown in FIG. 14, the current value of the peak of the light emitting efficiency and the light emitting area are approximately linearly related, and when the light emitting area decreases from 1600 μm2(e.g., 40 μm*40 μm) to 225 μm2(e.g., 15 μm*15 μm), the current value of the peak of the light emitting efficiency decreases by approximately 60%. In this way, the light emitting areas of the plurality of light emitting units 210 in the light emitting device 20 can be set based on the linear relationship between the current value of the peak of the light emitting efficiency and the light emitting area, and the required brightness.

[0144] In addition, as shown in FIG. 14, the current value corresponding to the peak of the light emitting efficiency of the light emitting unit 210 can be shifted to the left (decreased) by reducing the light emitting area of the light emitting unit 210. For example, in the case where the light emitting device 20 includes two light emitting units 210, the area of the upper light emitting unit 210 can be reduced to decrease the current value corresponding to the peak of the light emitting efficiency of the light emitting unit 210.

[0145] It should be noted that based on the relationship between the peak of the light emitting efficiency and the light emitting area, the current value corresponding to the peak of the light emitting efficiency of the light emitting unit 210 can be adjusted by reducing the light emitting area of the light emitting unit 210 in the case where the decrease of the peak of the light emitting efficiency is less than or equal to 10%, so as to adjust the current value corresponding to the peak of the light emitting efficiency in the case where the light emitting efficiency decreases slightly.

[0146] In some embodiments, as shown in FIG. 5 and FIG. 9, the ratio of the light emitting area of the second light emitting unit 212 to the light emitting area of the first light emitting unit 211 is 10% to 80%. Exemplarily, the ratio of the light emitting area of the second light emitting unit 212 to the light emitting area of the first light emitting unit 211 is 10%, 20%, 40%, 50%, 60%, 70% and 80%, which can be adjusted by adjusting the overlap and the overlap area of the conductive pattern 40, and the embodiments of the present disclosure are not limited thereto.

[0147] In some embodiments, referring to FIG. 7 and FIG. 8, the light emitting device 20 further comprises a first electrode 281 disposed on the upper surface of the uppermost second semiconductor layer 23. The first electrode 281 can be, for example, bonded to the driving backboard 10 to receive a first power signal.

[0148] It should be noted that the material of the first electrode 281 includes a transparent metal oxide. The transparent metal oxide refers to a metal oxide with a light transmittance greater than or equal to 90%. Exemplarily, the material of the first electrode 281 includes at least one of indium tin oxide, indium tin zinc oxide, indium gallium zinc oxide, indium tin zinc oxide and indium gallium tin oxide.

[0149] At this time, the light emitting device 20 can be a vertical package structure. The light emitting device 20 can be a Micro LED, and the radial length of the orthographic projection of the light emitting device 20 on the driving backboard 10 can be 30 μm to 40 μm. On this basis, after a plurality of light emitting devices 20 are massively transferred to the driving backboard 10, the first semiconductor layer 21 of the light emitting device 20 farthest from the first electrode 281 can be connected to the driving backboard 10 through the second electrode layer and the wiring to receive a second power signal. At the same time, in the light emitting device 20 of the vertical package structure, the light emitting unit 210 located at the lowermost side does not need to be prepared with a second electrode, so that the light emitting area of the light emitting unit 210 adjacent to the upper side thereof can be 80% of the light emitting area of the light emitting unit 210 at the lowermost side.

[0150] In other embodiments, referring to FIG. 10 and FIG. 11, the light emitting device 20 further comprises a first electrode 281 and a second electrode 282. The first electrode 281 is disposed on the upper surface of the uppermost second semiconductor layer 23, and the first electrode 281 can be, for example, bonded to the driving backboard 10 to receive a first power signal. The second electrode 282 is disposed on the upper surface of the edge portion of the first semiconductor layer 21 beyond the light emitting layer 22, and the second electrode 282 can also be, for example, bonded to the driving backboard 10 to receive a second power signal.

[0151] Here, the second electrode 282 can be a single-layer structure or a multi-layer structure. For example, the second electrode 282 includes a first sub-electrode 2821 and a second sub-electrode 2822 stacked, and the second sub-electrode 2822 is located on the upper side of the first sub-electrode 2821, the first sub-electrode 2821 is used to reduce the contact resistance, and the second sub-electrode 2822 is used to improve the welding yield. In FIGS. 10 and 11, the second electrode 282 is taken as an example including the first sub-electrode 2821 and the second sub-electrode 2822 for illustration, and the embodiments of the present disclosure are not limited thereto.

[0152] It should be noted that the materials of the first electrode 281 and the second electrode 282 include transparent metal oxides. The transparent metal oxide refers to a metal oxide with a light transmittance greater than or equal to 90%. For example, the materials of the first electrode 281 and the second electrode 282 include at least one of indium tin oxide, indium tin zinc oxide, indium gallium zinc oxide, indium tin zinc oxide, and indium gallium tin oxide.

[0153] At this time, the light emitting device 20 is in a flip-chip structure. Moreover, the light emitting device 20 can be a Micro LED or a Mini LED. For example, the light emitting device 20 can be a Micro LED, and the radial length of the orthographic projection of the light emitting device 20 on the driving backboard 10 can be 30 μm to 50 μm.

[0154] It should be noted that in the case of the light emitting device 20 in the flip-chip structure, the light emitting device 20 can further include the first substrate 110, and the plurality of light emitting units 210 are sequentially stacked on the first substrate 110.

[0155] In some examples, referring to FIGS. 9, 15, 16, and 17, the shape of the orthographic projection of the first semiconductor layer 21 on the reference surface is a rectangle, and the reference surface is the plane where the lowermost first semiconductor layer 21 is located.

[0156] On this basis, in the lowermost light emitting unit 210, the light emitting layer 22 exposes a corner region S of the first semiconductor layer 21, and the second electrode 282 is arranged in the corner region S, which is conducive to reducing the avoidance area of the light emitting layer 22, increasing the area of the light emitting layer 22, thereby increasing the light emitting area and improving the light emitting efficiency.

[0157] It should be noted that the boundary of the corner region S can be, for example, arc-shaped, so as to further reduce the avoidance area of the light emitting layer 22, increase the area of the light emitting layer 22, thereby increasing the light emitting area and improving the light emitting efficiency.

[0158] In some examples, as shown in FIG. 15, in the orthographic projection onto the reference plane, the second electrode 282 is located on one side of the first semiconductor layer 21-2 of the second light emitting unit 212 along the second direction Y. And, the conductive pattern 25 covers the first boundary L1 of the first semiconductor layer 21-2 of the corresponding second light emitting unit 212, the first boundary L1 is perpendicular to the second direction Y, and is located between the first electrode 281 and the second electrode 282. At this time, most of the current flows from the first boundary L1 to the second electrode 282, and the effective light emitting area can be considered as the M area shown in FIG. 15, and the effective light emitting area is 1 / 4 of the light emitting area.

[0159] In some examples, as shown in FIG. 16, in the orthographic projection onto the reference plane, the second electrode 282 is located on the extension line of the second boundary L2 of the first semiconductor layer 21-2 of the second light emitting unit 212. And, the conductive pattern 25 covers the second boundary L2 of the first semiconductor layer 21-2 of the corresponding second light emitting unit 212. At this time, most of the current flows from the second boundary L2 to the second electrode 282, and the effective light emitting area can be considered as the N area shown in FIG. 16, and the effective light emitting area is 1 / 4 of the light emitting area.

[0160] It should be noted that the first boundary L1 and the second boundary L2 can be two boundaries of the first semiconductor layer 21-2 of the second light emitting unit 212 close to the corner area S and intersecting.

[0161] In some examples, as shown in FIG. 17, in the orthographic projection onto the reference plane, the second electrode 282 is located on one side of the first semiconductor layer 21-2 of the second light emitting unit 212 along the second direction Y. And, the second electrode 282 is located on the extension line of the second boundary L2 of the first semiconductor layer 21-2 of the second light emitting unit 212.

[0162] On this basis, the conductive pattern 25 covers the first boundary L1 and the second boundary L2 of the first semiconductor layer 21-2 of the corresponding second light emitting unit 212. At this time, part of the current flows from the first boundary L1 to the second electrode 282, and part of the current flows from the second boundary L2 to the second electrode 282, and the effective light emitting area can be considered as the T area shown in FIG. 17, and the effective light emitting area is 1 / 2 of the light emitting area.

[0163] It should be understood that when the conductive pattern 25 covers all the boundaries of the first semiconductor layer 21-2 of the corresponding second light emitting unit 212, due to the close distance between the first boundary L1 and the second boundary L2 and the second electrode 282, most of the current still flows from the first boundary L1 and the second boundary L2 to the second electrode 282. Therefore, the conductive pattern 25 only covers the first boundary L1 and / or the second boundary L2, which can also reduce the preparation cost without a large decrease in the effective light emitting area.

[0164] Based on the above, the effective light-emitting area of the second light-emitting unit 212 can be adjusted by covering the first boundary of the first semiconductor layer 21-2 with the conductive pattern 25, so as to adjust the current value corresponding to the peak of the light-emitting efficiency.

[0165] In addition, when the light-emitting device 20 includes 3, 4 or more light-emitting units 210, the conductive pattern 25 can only cover the first boundary L1 and / or the second boundary L2, so as to reduce the light-shielding area of the conductive pattern 25 and improve the light extraction efficiency without a significant decrease in the effective light-emitting area.

[0166] In yet some embodiments, as shown in FIG. 18, the light-emitting device 20 further includes a first electrode 281, a second electrode 282, a conductive substrate 291 and a conductive bonding layer 292.

[0167] As shown in FIG. 18, the conductive substrate 291 is disposed on the upper side (lower side in FIG. 18) of the plurality of light-emitting units 210 to provide support. The conductive bonding layer 292 can be disposed between the conductive substrate 291 and the plurality of light-emitting units 210 to bond the conductive substrate 291 and the plurality of light-emitting units 210.

[0168] In addition, the first electrode 281 is disposed on the side of the first semiconductor layer 21 farthest from the conductive substrate 291, and the first electrode 281 can be, for example, bonded to the driving backboard 10 to receive a first power signal. The second electrode 282 is disposed on the side of the conductive substrate 291 farthest from the plurality of light-emitting units 210, and the second electrode 282 can, for example, cover the entire conductive substrate 291; the second electrode 282 can be, for example, connected to the driving backboard 10 by a wire to receive a second power signal.

[0169] At this time, the light-emitting device 20 can be a vertical structure. In addition, the light-emitting device 20 can be a Mini LED, and the radial length of the orthographic projection of the light-emitting device 20 on the driving backboard 10 can be greater than or equal to 50 μm. On this basis, the plurality of light-emitting devices 20 can be individually transferred to the driving backboard 10 for die bonding.

[0170] It should be understood that when the light-emitting color of the light-emitting device 20 is red, the first substrate 110 (see below for details) used in the process of forming the light-emitting device 20 by using the growth process can be a gallium arsenide substrate, and the first substrate 110 is opaque. In the flip-chip structure of the light-emitting device 20, the light-emitting device 20 also needs to be transferred again, resulting in a yield loss. Based on this, the light-emitting device 20 with a red light-emitting color can be a vertical structure to improve the production yield.

[0171] Some embodiments of the present disclosure also provide a preparation method of a light-emitting device 20, as shown in FIG. 19, which includes S100-S200.

[0172] S100: forming a plurality of light emitting units 210 and an adhesive layer 24.

[0173] In the above step, the plurality of light emitting units 210 are sequentially stacked, and the adhesive layer 24 is arranged between two adjacent light emitting units 210 to adhere and fix the two light emitting units 210.

[0174] The light emitting area of the light emitting unit 210 located at the lower side is greater than the light emitting area of the light emitting unit 210 located at the upper side. The light emitting unit 210 comprises a first semiconductor layer 21, a light emitting layer 22 and a second semiconductor layer 23 sequentially stacked, and at least part of the edge of the first semiconductor layer 21 exceeds the light emitting layer 22. The two adjacent light emitting units 210 are respectively a first light emitting unit 211 and a second light emitting unit 212, and at least part of the edge of the second semiconductor layer 23-1 of the first light emitting unit 211 exceeds the first semiconductor layer 21-2 of the second light emitting unit 212.

[0175] In some embodiments, as shown in FIG. 20, S100 comprises S110-S140.

[0176] FIGS. 21-24 are preparation step diagrams of a preparation method of a light emitting device with a vertical structure according to some embodiments; and FIGS. 25-29 are preparation step diagrams of a preparation method of a light emitting device with a flip-chip structure according to some embodiments.

[0177] S110: as shown in FIGS. 21 and 25, forming a first light emitting unit 211 on a first substrate 110.

[0178] In the above step, the first semiconductor film 21', the light emitting film 22' and the second semiconductor film 23' can be sequentially formed on the first substrate 110 by a growth process; then, the first semiconductor film 21', the light emitting film 22' and the second semiconductor film 23' are divided into a plurality of first light emitting units 211 arranged at intervals by an etching process, and the light emitting layer 22 and the second semiconductor layer 23 are recessed compared with the first semiconductor layer 21 to form a step. It should be noted that the first substrate 110 can be any one of a sapphire substrate, a silicon substrate and a gallium arsenide substrate, and the embodiments of the present disclosure are not limited thereto.

[0179] S120: as shown in FIGS. 22 and 26, forming a second light emitting unit 212 on a second substrate 120.

[0180] In the above steps, the first semiconductor thin film 21', the light-emitting thin film 22' and the second semiconductor thin film 23' can be sequentially formed on the second substrate 120 by a growth process; and then, the first semiconductor thin film 21', the light-emitting thin film 22' and the second semiconductor thin film 23' are divided into a plurality of second light-emitting units 212 arranged at intervals by an etching process, and the light-emitting layer 22 and the second semiconductor layer 23 are retracted into the first semiconductor layer 21 to form a step. The light-emitting area of the second light-emitting unit 212 is smaller than the light-emitting area of the first light-emitting unit 211.

[0181] It should be noted that the second substrate 120 can be any one of a sapphire substrate, a silicon substrate and a gallium arsenide substrate, and the embodiments of the present disclosure are not limited thereto. In addition, the order of S110 and S120 is not fixed, and S110 can be performed first, and then S120 can be performed; or S120 can be performed first, and then S110 can be performed; or S110 and S120 can be performed simultaneously.

[0182] S130: As shown in FIGS. 23 and 27, the third substrate 130 is connected to the side of the second light-emitting unit 212 away from the second substrate 120 by the temporary bonding glue 30, and the second substrate 120 is removed.

[0183] In the above steps, the second substrate 120 can be removed by any one of mechanical grinding, mechanical peeling and an etching process. In addition, the material of the temporary bonding glue 30 includes resin and / or polydimethylsiloxane, so that the third substrate 130 and the second light-emitting unit 212 are dissociated in subsequent processes. It should be noted that the third substrate 130 can be any one of a sapphire substrate, a silicon substrate, a glass substrate and a gallium arsenide substrate, and the embodiments of the present disclosure are not limited thereto.

[0184] S140: As shown in FIGS. 24 and 28, the side of the second light-emitting unit 212 away from the third substrate 130 is connected to the side of the first light-emitting unit 211 away from the first substrate 110 by the adhesive layer 24, and the third substrate 130 is removed.

[0185] In the above steps, the adhesive layer 24 can be formed on the side of the second light-emitting unit 212 away from the third substrate 130, or on the side of the first light-emitting unit 211 away from the first substrate 110 by a coating or printing process. In addition, the third substrate 130 can be removed by any one of mechanical grinding, mechanical peeling and an etching process. For example, the third substrate 130 can be dissociated by laser, so that the temporary bonding glue 30 and the third substrate 130 are removed.

[0186] In the case where the light-emitting device 20 is a flip structure, between S110 and S130, referring to FIGS. 29 and 30, S100 further includes S150.

[0187] S150: As shown in FIG. 29, the first sub-electrode 2821 is formed.

[0188] In the above step, the first sub-electrode 2821 is arranged on the upper surface of the edge portion of the first semiconductor layer 21 beyond the light-emitting layer 22, i.e., the first sub-electrode 2821 is arranged on the step to reduce the contact resistance. In this embodiment of the present disclosure, the first sub-electrode 2821 can be formed by using a mask and a vapor deposition process, but the present disclosure is not limited thereto.

[0189] In this case, after the first light-emitting unit 211 is prepared, the first sub-electrode 2821 is directly in contact with the first semiconductor layer 21, so that subsequent other film layers (such as the second barrier layer 282) can be prevented from being over-etched or incompletely removed, thereby causing poor conductive connection between the first sub-electrode 2821 and the first semiconductor layer 21.

[0190] S200: As shown in FIGS. 31 and 32, the conductive pattern 25 is formed.

[0191] In the above step, the conductive pattern 25 is connected with the two adjacent light-emitting units 210. Moreover, one part of the conductive pattern 25 is in electrical contact with the edge portion of the first semiconductor layer 21-2 of the second light-emitting unit 212 beyond the second semiconductor layer 23-1 of the first light-emitting unit 211, and the other part is in electrical contact with the edge portion of the first semiconductor layer 21-2 of the second light-emitting unit 212 beyond the light-emitting layer 22-2. In this embodiment of the present disclosure, the conductive pattern 25 can be formed by using a mask and a vapor deposition process, but the present disclosure is not limited thereto.

[0192] In some embodiments, as shown in FIG. 33, S300 is further included before S200.

[0193] S300: As shown in FIGS. 34 and 35, the second barrier film 27' is formed.

[0194] In the above step, the second barrier film 27' covers the first light-emitting unit 211, the second light-emitting unit 212, and the adhesive layer 24. Moreover, the second barrier film 27' is provided with a first connecting hole 271 and a second connecting hole 272, the first connecting hole 271 exposes the first semiconductor layer 21-2 of the second light-emitting unit 212, and the second connecting hole 272 exposes the second semiconductor layer 23-1 of the first light-emitting unit 211.

[0195] On this basis, in combination with FIG. 11, the conductive pattern 25 extends into the first connecting hole 271 and the second connecting hole 272 and is in electrical contact with the first semiconductor layer 21-2 and the second semiconductor layer 23-1, respectively. Moreover, the second barrier layer 27 is the part of the second barrier film 27' located between the conductive pattern 25 and the light-emitting unit 210.

[0196] In some embodiments, as shown in FIG. 33, after S200, the above preparation method further comprises S400.

[0197] S400: As shown in FIGS. 36 and 37, the first barrier film 26' is formed.

[0198] In the above step, the first barrier film 26' covers the conductive pattern 25, and the first light emitting unit 211 and the second light emitting unit 212 expose the surfaces close to the side of the conductive pattern 25. At this time, the first barrier layer 26 is the part of the first barrier film 26' and the second barrier film 27' located outside the conductive pattern 25.

[0199] In the above step, the first barrier film 26' covers the conductive pattern 25, and the first light emitting unit 211 and the second light emitting unit 212 expose the surfaces close to the side of the conductive pattern 25. At this time, the first barrier layer 26 is the part of the first barrier film 26' and the second barrier film 27' located outside the conductive pattern 25.

[0200] In the case that the light emitting device 20 is a vertical structure, and the light emitting device 20 can be transferred to the driving backboard 10 in large quantities, and then connected to the driving backboard 10 through the second electrode layer and the wire to receive the second power signal, such as the case that the light emitting device 20 is a Micro LED, as shown in FIG. 33, after S400, the above preparation method further comprises S500.

[0201] S500: As shown in FIG. 38, the first electrode 281 is formed.

[0202] In the above step, the first electrode 281 extends into the first via and electrically contacts the second semiconductor layer 23-2 to provide the first power signal. In the above step, the first electrode 281 can be formed by using a mask and a vapor deposition process, but the embodiments of the present disclosure are not limited thereto.

[0203] It should be understood that in the process of S200-S500, the first substrate 110 can still be used to provide support, and after S500, the first substrate 110 can be removed to form the light emitting device 20.

[0204] In the case that the light emitting device 20 is a vertical structure, and the light emitting device 20 can be individually transferred to the driving backboard 10 for die bonding, such as the case that the light emitting device 20 is a Mini LED, as shown in FIG. 39, after S400, the above preparation method further comprises S610-S620.

[0205] S610: As shown in FIG. 40, the conductive substrate 291 is connected to the second light emitting units 212 away from the first substrate 110 by the conductive bonding layer 292, and the first substrate 110 is removed.

[0206] In the above steps, the first substrate 110 can be removed by any one of mechanical grinding, mechanical peeling and etching process. In addition, the conductive bonding layer 292 includes conductive glue, and the conductive substrate 291 can be a silicon substrate.

[0207] S620: As shown in FIG. 41, the first electrode 281 and the second electrode 282 are formed.

[0208] In the above steps, the first electrode 281 is disposed on the side of the first semiconductor layer 21 farthest from the conductive substrate 291 away from the conductive substrate 291, and the second electrode 282 is disposed on the side of the conductive substrate 291 away from the plurality of light emitting units 210. The first electrode 281 and the second electrode 282 can be formed by using a mask and a vapor deposition process, but the present disclosure is not limited thereto.

[0209] It should be noted that in S610, the plurality of second light emitting units 212 can be connected to one conductive substrate 291 through the conductive bonding layer 292. At this time, after S620, the conductive substrate 291 and the conductive bonding layer 292 need to be cut to form a plurality of independent light emitting devices 20.

[0210] In the case of the flip-chip structure of the light emitting device 20, as shown in FIG. 42, after S400, the above preparation method further includes S700.

[0211] S700: As shown in FIG. 43, the first electrode 281 and the second sub-electrode 2822 are formed.

[0212] In the above steps, the first electrode 281 extends into the first via to electrically contact the second semiconductor layer 23-2 to provide a first power signal. The second sub-electrode 2822 is located on the side of the first sub-electrode 2821 away from the first semiconductor layer 21-1 of the first light emitting unit 211, and electrically contacts the first sub-electrode 2821. At this time, the first sub-electrode 2821 and the second sub-electrode 2822 form the second electrode 282. The first electrode 281 and the second sub-electrode 2822 can be formed by using a mask and a vapor deposition process, but the present disclosure is not limited thereto.

[0213] It should be understood that during S200-S400 and S700, the first substrate 110 can still provide support, and after S700, the first substrate 110 is removed to form the light emitting device 20.

[0214] In the description of the present specification, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in an appropriate manner.

[0215] The above description is merely a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who thinks of changes or replacements within the technical range disclosed by the present disclosure should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A light-emitting device, comprising: Multiple light-emitting units are stacked sequentially, and the light-emitting area of ​​the lower light-emitting unit is greater than the light-emitting area of ​​the upper light-emitting unit. The light-emitting unit includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer stacked sequentially, with at least a portion of the edge of the first semiconductor layer extending beyond the light-emitting layer; and two adjacent light-emitting units are a first light-emitting unit and a second light-emitting unit, with at least a portion of the edge of the second semiconductor layer of the first light-emitting unit extending beyond the first semiconductor layer of the second light-emitting unit; An adhesive layer is disposed between two adjacent light-emitting units; A conductive pattern is connected to two adjacent light-emitting units; a portion of the conductive pattern is electrically contacted with the edge portion of the second semiconductor layer of the first light-emitting unit that extends beyond the first semiconductor layer of the second light-emitting unit, and another portion is electrically contacted with the edge portion of the first semiconductor layer of the second light-emitting unit that extends beyond the light-emitting layer.

2. The light-emitting device according to claim 1, further comprising: A first barrier layer covers the conductive pattern and the exposed surface of the plurality of light-emitting units on the side closest to the conductive pattern.

3. The light-emitting device according to claim 1 or 2, further comprising: A second barrier layer is disposed between the conductive pattern and the light-emitting unit; The second barrier layer is provided with a first connection hole and a second connection hole; the conductive pattern extends into the first connection hole and the second connection hole, and makes electrical contact with the first semiconductor layer and the second semiconductor layer, respectively.

4. The light-emitting device according to claim 3, comprising a first blocking layer, the first blocking layer comprising: The first sub-section covers the exposed surface of the plurality of light-emitting units on the side closest to the conductive pattern; The second sub-part covers the conductive pattern; the thickness of the first sub-part is greater than the thickness of the second sub-part.

5. The light-emitting device according to any one of claims 1 to 4, wherein, The conductive pattern includes: The first overlapping portion is disposed on the second semiconductor layer; The second overlapping portion is disposed on the first semiconductor layer; A first connecting portion is disposed between the first overlapping portion and the second overlapping portion, with one end connected to the first overlapping portion and the other end connected to the second overlapping portion.

6. The light-emitting device according to claim 5, wherein, In the first cross-section, the length of the first overlap and / or the second overlap is greater than or equal to 1 μm; the first cross-section is perpendicular to the plane containing the first semiconductor layer and perpendicular to the boundary where the first semiconductor layer contacts the second overlap; and / or, The distance between the boundary of the first overlapping portion and the boundary of the second semiconductor layer of the connected first light-emitting unit is 0 μm to 5 μm; and / or, The distance between the boundary of the second overlapping portion and the boundary of the light-emitting layer of the connected second light-emitting unit is 0μm to 5μm.

7. The light-emitting device according to claim 5 or 6, wherein, On the first cross section, along the first direction, the length of the first connecting portion is 2μm to 4μm; the first cross section is perpendicular to the plane where the first semiconductor layer is located, and perpendicular to the boundary where the first semiconductor layer contacts the second overlapping portion; the first direction is parallel to the plane where the first semiconductor layer is located; and / or, the angle between the first connecting portion and the second semiconductor layer is 60° to 80°.

8. The light-emitting device according to any one of claims 1 to 7, wherein, The peak current values ​​corresponding to the luminous efficiency of at least two of the light-emitting units are not equal.

9. The light-emitting device according to claim 8, comprising two light-emitting units, wherein the ratio of the current value corresponding to the peak luminous efficiency of one light-emitting unit to the current value corresponding to the peak luminous efficiency of the other light-emitting unit is 5 to 20.

10. The light-emitting device according to claim 8 or 9, wherein, The peak current value corresponding to the luminous efficiency of the light-emitting unit is less than or equal to 0.5mA.

11. The light-emitting device according to any one of claims 1 to 10, wherein, The ratio of the light-emitting area of ​​the second light-emitting unit to the light-emitting area of ​​the first light-emitting unit is 10% to 80%.

12. The light-emitting device according to any one of claims 1 to 11, further comprising: The first electrode is disposed on the upper surface of the uppermost second semiconductor layer.

13. The light-emitting device according to claim 12, further comprising: The second electrode is disposed on the upper surface of the lowermost portion of the first semiconductor layer that extends beyond the edge of the light-emitting layer.

14. The light-emitting device according to claim 13, wherein, The shape of the orthographic projection of the first semiconductor layer onto the reference plane is rectangular, and the reference plane is the plane where the first semiconductor layer is located at the bottom. Furthermore, in the light-emitting unit located at the bottom, the light-emitting layer exposes a corner region of the first semiconductor layer, and the second electrode is disposed in the corner region.

15. The light-emitting device according to claim 14, wherein, In the orthographic projection onto the reference plane, along the second direction, the second electrode is located on one side of the first semiconductor layer of the second light-emitting unit; and the conductive pattern covers the first boundary of the first semiconductor layer of the corresponding second light-emitting unit, the first boundary being perpendicular to the second direction and located between the first electrode and the second electrode.

16. The light-emitting device according to claim 14 or 15, wherein, In the orthographic projection onto the reference plane, the second electrode is located on the extension line of the second boundary of the first semiconductor layer of the second light-emitting unit; and the conductive pattern covers the second boundary of the first semiconductor layer of the corresponding second light-emitting unit.

17. The light-emitting device according to any one of claims 1 to 11, further comprising: A conductive substrate is disposed on the upper side of the plurality of light-emitting units; A conductive bonding layer is disposed between the conductive substrate and the plurality of light-emitting units; The first electrode is disposed on the side of the first semiconductor layer furthest from the conductive substrate. The second electrode is disposed on the side of the conductive substrate away from the plurality of light-emitting units.

18. A light-emitting substrate, comprising: Drive backplane; The light-emitting device as described in any one of claims 1 to 17, wherein the light-emitting device is connected to the driving backplate.

19. A display device comprising a light-emitting substrate as described in claim 18.

20. A method for fabricating a light-emitting device, comprising: Multiple light-emitting units and an adhesive layer are formed; The plurality of light-emitting units are stacked sequentially, and the light-emitting area of ​​the lower light-emitting unit is larger than that of the upper light-emitting unit; each light-emitting unit includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer stacked sequentially, with at least a portion of the edge of the first semiconductor layer extending beyond the light-emitting layer; and two adjacent light-emitting units are respectively a first light-emitting unit and a second light-emitting unit, with at least a portion of the edge of the second semiconductor layer of the first light-emitting unit extending beyond the first semiconductor layer of the second light-emitting unit; the adhesive layer is disposed between two adjacent light-emitting units; A conductive pattern is formed; the conductive pattern is connected to two adjacent light-emitting units; and a portion of the conductive pattern is electrically contacted with the edge portion of the second semiconductor layer of the first light-emitting unit that extends beyond the first semiconductor layer of the second light-emitting unit, and another portion is electrically contacted with the edge portion of the first semiconductor layer of the second light-emitting unit that extends beyond the light-emitting layer.

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