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 devices and their fabrication methods, light-emitting substrates and display devices

[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] This disclosure relates to the field of display technology, and in particular to a light-emitting device, a method for fabricating the same, a light-emitting substrate, and a display device. Background Technology

[0003] With the development of light-emitting diode (LED) technology, display devices using LEDs at the sub-millimeter (Mini) or even micrometer (Micro) scale have been widely adopted. This allows display devices using Micro LEDs or Mini LEDs to achieve the same contrast ratio as Organic Light Emitting Diode (OLED) displays, while retaining the advantages of liquid crystal displays such as low cost, high brightness, and high reliability. Ultimately, this enhances the display effect and provides users with a superior visual experience. Summary of the Invention

[0004] On one hand, a light-emitting device is provided. The light-emitting device includes a plurality of light-emitting units, an adhesive layer, and a conductive pattern stacked sequentially. The light-emitting area of ​​the lower light-emitting unit is larger than the light-emitting area 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. Furthermore, 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.

[0005] The adhesive layer is disposed between two adjacent light-emitting units. The conductive pattern is connected to the two adjacent light-emitting units. A portion of the conductive pattern is in electrical contact 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 in electrical contact with the edge portion of the first semiconductor layer of the second light-emitting unit that extends beyond the light-emitting layer.

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

[0007] In some embodiments, the light-emitting device further includes a second barrier layer disposed between the conductive pattern and the light-emitting unit. The second barrier layer has a first connection hole and a second connection hole. The conductive pattern extends into the first connection hole and the second connection hole, respectively making electrical contact with the first semiconductor layer and the second semiconductor layer.

[0008] In some embodiments, the light-emitting device includes a first blocking layer, the first blocking layer including a first sub-section and a second sub-section. The first sub-section covers the exposed surface of the plurality of light-emitting units near the conductive pattern. The second sub-section covers the conductive pattern. The thickness of the first sub-section is greater than the thickness of the second sub-section.

[0009] In some embodiments, the conductive pattern includes a first overlap, a second overlap, and a first connection. The first overlap is disposed on the second semiconductor layer. The second overlap is disposed on the first semiconductor layer. The first connection is disposed between the first overlap and the second overlap, with one end connected to the first overlap and the other end connected to the second overlap.

[0010] In some embodiments, in a first cross-section, the length of the first overlapping portion and / or the second overlapping portion 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 overlapping portion. 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 0 μm to 5 μm.

[0011] In some embodiments, the length of the first connection portion along a first direction in a first cross-section is 2 μm to 4 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 portion; the first direction is parallel to the plane containing the first semiconductor layer. And / or, the angle between the first connection portion and the second semiconductor layer is 60° to 80°.

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

[0013] In some embodiments, the light-emitting device includes 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.

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

[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 includes a first electrode disposed on the upper surface of the uppermost second semiconductor layer.

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

[0018] In some embodiments, the orthographic projection of the first semiconductor layer onto a reference plane is rectangular, and the reference plane is the plane containing the lowermost first semiconductor layer. Furthermore, in the lowermost light-emitting unit, the light-emitting layer exposes a corner region of the first semiconductor layer, and the second electrode is disposed in the corner region.

[0019] In some embodiments, in an orthographic projection onto the reference plane, the second electrode is located on one side of the first semiconductor layer of the second light-emitting unit along the second direction. Furthermore, 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.

[0020] In some embodiments, in an 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. Furthermore, 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 includes a conductive substrate, a conductive bonding layer, a first electrode, and a second electrode. The conductive substrate is disposed above 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 furthest from the conductive substrate. The second electrode is disposed on the side of the conductive substrate furthest from the plurality of light-emitting units.

[0022] On the other hand, a light-emitting substrate is provided. The light-emitting substrate includes a driving backplate and a light-emitting device as described in any of the above embodiments, wherein the light-emitting device is connected to the driving backplate.

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

[0024] In another aspect, a method for fabricating 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 stacked sequentially, and the light-emitting area of ​​the lower light-emitting unit is larger than the light-emitting area 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. Furthermore, 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.

[0025] A conductive pattern is formed. The conductive pattern is connected to two adjacent light-emitting units. A portion of the conductive pattern is in electrical contact 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 in electrical contact with the edge portion of the first semiconductor layer of the second light-emitting unit that extends beyond the light-emitting layer. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in this disclosure, the accompanying drawings used in some embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not intended to limit the actual size of the product, the actual flow of the method, the actual timing of the signals, etc. involved in the embodiments of this disclosure.

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

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

[0029] Figure 3 is a cross-sectional view along section line AA in Figure 1;

[0030] Figure 4 is another sectional view along section line AA in Figure 1;

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

[0032] Figure 6 is a cross-sectional view along section line BB in Figure 5;

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

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

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

[0036] Figure 10 is a structural diagram of another light-emitting device according to some embodiments;

[0037] Figure 11 is a structural diagram of another light-emitting device according to some embodiments;

[0038] Figure 12 is a graph showing the relationship between the luminous efficiency and current of three light-emitting devices according to some embodiments;

[0039] Figure 13 is a graph showing the relationship between the luminous efficiency and current of two light-emitting units in the same light-emitting device according to some embodiments;

[0040] Figure 14 is a comparison of the peak current and peak luminous efficiency of the light-emitting device under different light-emitting areas according to some embodiments;

[0041] Figure 15 is a top view of another light-emitting device according to some embodiments;

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

[0043] Figure 17 is a top view of yet another light-emitting device according to some embodiments;

[0044] Figure 18 is a structural diagram of another light-emitting device according to some embodiments;

[0045] Figure 19 is a flowchart of a method for fabricating a light-emitting device according to some embodiments;

[0046] Figure 20 is a flowchart of a method for fabricating a light-emitting device according to some embodiments;

[0047] Figures 21 to 24 are step diagrams illustrating the fabrication process of a vertically mounted light-emitting device according to some embodiments;

[0048] Figures 25 to 29 are step diagrams illustrating the fabrication process of a flip-chip light-emitting device according to some embodiments;

[0049] Figure 30 is a flowchart of a method for fabricating a light-emitting device according to some embodiments;

[0050] Figure 31 is a flowchart illustrating the fabrication steps of a vertically mounted light-emitting device according to some embodiments;

[0051] Figure 32 is a flowchart illustrating the fabrication steps of a flip-chip light-emitting device according to some embodiments;

[0052] Figure 33 is a flowchart of a method for fabricating a light-emitting device according to some embodiments;

[0053] Figure 34 is a diagram showing the fabrication steps of a vertically mounted light-emitting device according to some embodiments;

[0054] Figure 35 is a flowchart illustrating the fabrication steps of a flip-chip light-emitting device according to some embodiments;

[0055] Figure 36 is a flowchart illustrating the fabrication steps of a vertically mounted light-emitting device according to some embodiments;

[0056] Figure 37 is a flowchart illustrating the fabrication steps of a flip-chip light-emitting device according to some embodiments;

[0057] Figure 38 is a flowchart illustrating the fabrication steps of a vertically mounted light-emitting device according to some embodiments;

[0058] Figure 39 is a flowchart of a method for fabricating a light-emitting device according to some embodiments;

[0059] Figure 40 is a flowchart illustrating the fabrication steps of a vertically mounted light-emitting device according to some embodiments;

[0060] Figure 41 is a diagram showing the fabrication steps of a vertically mounted light-emitting device according to some embodiments;

[0061] Figure 42 is a flowchart of a method for fabricating a light-emitting device according to some embodiments;

[0062] Figure 43 is a diagram illustrating the fabrication steps of a flip-chip structure light-emitting device according to some embodiments. Detailed Implementation

[0063] The technical solutions in some embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this disclosure are within the scope of protection of this disclosure.

[0064] Unless the context otherwise requires, throughout the specification and claims, the term "comprise" and its other forms, such as the third-person singular "comprises" and the present participle "comprising," are interpreted as open-ended and encompassing, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiments," "example," "specific example," or "some examples," etc., are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0065] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0066] In describing some embodiments, the terms "coupled" and "connected," and their derivative expressions, may be used. The term "connected" should be interpreted broadly; for example, a "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection via an intermediate medium. The term "coupled," for example, indicates that two or more components have direct physical or electrical contact. The term "coupled" or "communicatively coupled" may also refer to two or more components that 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 of this document.

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

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

[0069] The use of “applies to” or “configured to” in this article implies an open and inclusive language that does not preclude applicability to or configuration to devices that perform additional tasks or steps.

[0070] In addition, the use of “based on” implies openness and inclusivity, because processes, steps, calculations or other actions “based on” one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0071] As used herein, “about,” “approximately,” or “approximately” includes the stated value and the average value within an acceptable range of deviation from the given value, wherein the acceptable range of deviation is determined by a person skilled in the art taking into account the measurement under discussion and the error associated with the measurement of the given quantity (i.e., the limitations of the measurement system).

[0072] As used herein, “parallel,” “perpendicular,” and “equal” include the described situation and situations that are similar to the described situation, within an acceptable range of deviation, which is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “equal” includes absolute equality and approximate equality, where an acceptable range of deviation for approximate equality may be, for example, a difference between the two equal items less than or equal to 5% of either one.

[0073] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can mean that the layer or element is directly on the other layer or substrate, or that there is an intermediate layer between the layer or element and the other layer or substrate.

[0074] This document describes exemplary embodiments with reference to cross-sectional views and / or plan views, which are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as being limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes. For example, etched areas shown as rectangular would typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the areas of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0075] As shown in Figures 1 and 2, some embodiments of this disclosure provide a display device 1000, which can be any device that displays images, whether moving (e.g., video) or fixed (e.g., still images) and whether it is text or images.

[0076] For example, referring to Figures 1 and 2, the display device 1000 can be any product or component with display function, such as a television, laptop computer, tablet computer, in-vehicle display, in-flight display, portable display product (e.g., mobile phone), wearable device (e.g., watch), camera, camcorder, projector, calculator, wireless device, personal digital assistant (PDA), clock, Global Positioning System (GPS) receiver / navigator, virtual reality (VR) device, augmented reality (AR) device, electronic billboard or sign, etc.

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

[0078] It should be noted that, depending on the application scenario, the display device 1000 can be a flat display device, a curved display device, or a foldable display device, etc., and the shape of the display surface of the display device 1000 can be any of a circle, an ellipse, a polygon, or an irregular shape. The embodiments disclosed herein are not limited to these.

[0079] The following uses the mobile phone shown in FIG1 as an example to illustrate some embodiments of the present disclosure. However, the implementation of the present disclosure is not limited to this, and any other display device can be considered as long as the same technical concept is applied.

[0080] In some embodiments, referring to FIG3 and FIG4, the display device 1000 includes a light-emitting substrate 100, which has opposing light-emitting side and non-light-emitting side. The light-emitting side refers to the side of the light-emitting substrate 100 that can emit light (the upper side of the light-emitting substrate 100 in FIG3 and FIG4), and the non-light-emitting side refers to the other side opposite to the light-emitting side (the lower side of the light-emitting substrate 100 in FIG3 and FIG4).

[0081] For example, referring to Figures 3 and 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 disposed 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 to the light-emitting substrate 100 to provide light emission signals to the light-emitting substrate 100.

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

[0083] It should be understood that the above-mentioned display device 1000 may be a liquid crystal display (LCD) or a mini / micro light emitting display (MLED), and the embodiments disclosed herein do not specifically limit it.

[0084] In some embodiments, as shown in FIG3, the display device 1000 can be a liquid crystal display device. In this case, the light-emitting substrate 100 can serve as a backlight in the liquid crystal display device to provide backlight for the display panel 500. The display panel 500 can adjust the intensity (grayscale) of the light passing through the display panel 500, thereby realizing image display.

[0085] For example, referring to FIG3, the display device 1000 further includes a display panel 500, which is disposed on the light-emitting side of the light-emitting substrate 100. The display panel 500 may be, for example, a liquid crystal display panel.

[0086] The light-emitting substrate 100 can directly emit white light. After being homogenized, the white light is directed onto the display panel 500. The display panel 500 adjusts the intensity (grayscale) of the light passing through it and performs color conversion to achieve full-color display.

[0087] Alternatively, the light-emitting substrate 100 can emit light of other colors (such as blue), which is then converted and homogenized before being directed onto the display panel 500. The display panel 500 adjusts the intensity (grayscale) of the light passing through it to achieve full-color display.

[0088] Alternatively, the light-emitting substrate 100 can emit light of multiple colors (e.g., red, blue, and green), which is then homogenized and directed onto the display panel 500. The display panel 500 adjusts the intensity (grayscale) of the light passing through it to achieve full-color display.

[0089] In some other embodiments, referring to FIG4, the display device 1000 can be a miniature light-emitting display device. In this case, the light-emitting substrate 100 can serve as the display panel of the miniature light-emitting display device for direct display.

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

[0091] The following description uses the display device 1000 as an example of a miniature light-emitting display device to illustrate some embodiments of the present disclosure. However, the implementation of the present disclosure is not limited thereto, and any other display device can be considered as long as the same technical concept is applied.

[0092] In some embodiments, referring to FIG3 and FIG4, the light-emitting substrate 100 includes a driving back plate 10 and a light-emitting device 20. The light-emitting device 20 is disposed on the driving back plate 10 and connected to the driving back plate 10 to receive a first power signal and a second power signal, thereby driving 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 power voltage to the light-emitting device 20. For example, the first power signal is connected to the positive terminal of the power supply, and the second power signal is connected to the negative terminal of the power supply.

[0094] The orthographic projection of the light-emitting device 20 onto the driving backplate 10 can be any of a circle, an ellipse, and a polygon, and the embodiments disclosed herein are not limited thereto. Furthermore, the light-emitting device 20 may include a Micro LED and / or a Mini LED. For example, the radial length of the orthographic projection of a Micro LED onto the driving backplate 10 is less than 50 μm, such as 10 μm to 50 μm. As another example, the radial length of the orthographic projection of a Mini LED onto 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 an orthographic projection refers to the length of the line segment connecting two points on the orthographic projection boundary, with the connecting line segment passing through the geometric center of the orthographic projection. For example, when the orthographic projection is a quadrilateral, this radial length includes the side lengths and the lengths of the diagonals. For example, when the orthographic projection is a circle, this radial length is the diameter.

[0096] In some embodiments, referring to Figures 3 and 4, the light-emitting substrate 100 further includes an encapsulation layer 600, which covers the light-emitting device 20 to protect it. The encapsulation layer 600 is made of transparent silicone.

[0097] In some embodiments, referring to Figures 5 and 6, the light-emitting device 20 includes a plurality of light-emitting units 210 connected in series. Each light-emitting unit 210 includes a first semiconductor layer 21, a light-emitting layer 22, and a second semiconductor layer 23 stacked sequentially, i.e., the light-emitting layer 22 is disposed between the first semiconductor layer 21 and the second semiconductor layer 23. In this case, the overlapping area of ​​the first semiconductor layer 21, the light-emitting layer 22, and the second semiconductor layer 23 is the light-emitting area of ​​one light-emitting unit 210. In this situation, the light-emitting device 20 can use a high-voltage transmission drive signal to form a high-voltage driven light-emitting device 20, thereby reducing the drive 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 back plate 10 can be any of a circle, an ellipse, and a polygon, and the embodiments disclosed herein are not limited thereto.

[0099] In this structure, 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. When a voltage is applied to the light-emitting unit 210, electrons in the N-type semiconductor layer migrate to and enter the light-emitting layer 22. Holes in the P-type semiconductor layer also migrate to and enter the light-emitting layer 22. The electrons and holes entering the light-emitting layer 22 recombine, thereby generating spontaneous emission of light.

[0100] The following describes some embodiments of the present disclosure by taking the first semiconductor layer 21 as an N-type semiconductor layer and the second semiconductor layer 23 as a P-type semiconductor layer as an example. However, the implementation of the present disclosure is not limited to this, and it is also possible to consider the first semiconductor layer 21 as a P-type semiconductor layer and the second semiconductor layer 23 as an N-type semiconductor layer, as long as the same technical concept is applied.

[0101] In some embodiments, referring to Figures 4, 5 and 6, a plurality of light-emitting units 210 are stacked sequentially along a direction perpendicular to the driving back plate 10. In this way, the orthographic projections of the plurality of light-emitting units 210 on the driving back plate 10 at least partially overlap, and they can jointly occupy a portion of the area on the driving back plate 10, thereby compressing the area occupied by the light-emitting devices 20 on the driving back plate 10, which is beneficial to increasing the arrangement density of the light-emitting devices 20 on the driving back plate 10, and thus improving the resolution of the display device 1000.

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

[0103] In related technologies, multiple light-emitting units are connected using a transparent conductive layer (such as heavily doped N-type gallium nitride) formed by a growth process, or by a bonding process to connect multiple light-emitting units through a transparent conductive layer (indium tin oxide or indium gallium zinc oxide). However, this method suffers from low production efficiency and yield. The inventors' research revealed that both processes require balancing the reliability of the connection with the conductivity of the transparent conductive layer during formation. This makes the process uncontrollable and challenging, leading to decreased production efficiency and yield.

[0104] Based on this, referring to Figures 5 and 6, some embodiments of this disclosure provide a light-emitting device 20, which also includes an adhesive layer 24 and a conductive pattern 25.

[0105] The adhesive layer 24 may be made of transparent benzocyclobutene. The conductive pattern 25 may be made of a metallic material, for example, the conductive pattern 25 may be made of at least one of gold, silver, aluminum, tungsten, nickel, copper and iron.

[0106] The adhesive layer 24 is disposed between two adjacent light-emitting units 210 to bond and fix the two light-emitting units 210 together, and the conductive pattern 25 is connected to two adjacent light-emitting units 210 so that multiple light-emitting units 210 are connected in series.

[0107] For example, referring to Figures 6 and 10, among the multiple light-emitting units 210 stacked in sequence, the light-emitting area of ​​the light-emitting unit 210 located on the lower side is greater than the light-emitting area of ​​the light-emitting unit 210 located on the upper side, and at least a portion of the edge of the first semiconductor layer 21 extends beyond the light-emitting layer 22.

[0108] For ease of distinction, two adjacent light-emitting units 210 are designated as the first light-emitting unit 211 and the second light-emitting unit 212, respectively. The first semiconductor layers 21 of the first light-emitting unit 211 and the second light-emitting unit 212 are designated as 21-1 and 21-2, respectively. The light-emitting layers 22 of the first light-emitting unit 211 and the second light-emitting unit 212 are designated as 22-1 and 22-2, respectively. The second semiconductor layers 23 of the first light-emitting unit 211 and the second light-emitting unit 212 are designated as 23-1 and 23-2, respectively.

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

[0110] Based on this, as shown in Figures 5, 6, 9 and 10, a portion of the conductive pattern 25 is in electrical contact with the edge portion of the second semiconductor layer 23-1 of the first light-emitting unit 211 that extends beyond the edge portion of the first semiconductor layer 21-2 of the second light-emitting unit 212, and another portion is in electrical contact with the edge portion of the first semiconductor layer 21-2 of the second light-emitting unit 212 that extends beyond the edge portion of the light-emitting layer 22-2.

[0111] In this configuration, the multiple light-emitting units 210 stacked sequentially can be bonded together using an adhesive layer 24, and electrically connected via conductive patterns 25 using deposition and / or patterning processes. In this case, the formation of the adhesive layer 24 does not require consideration of conductivity; the bonding process alone ensures a reliable connection between the multiple light-emitting units 210, resulting in a low-difficulty process. Furthermore, the formation of the conductive patterns 25 does not require consideration of the reliability of the connection between the multiple light-emitting units 210; the deposition and / or patterning process alone ensures a good conductive connection, further reducing the difficulty of the process. As can be seen from the above, compared with related technologies, the fabrication process of the light-emitting device 20 provided in this embodiment is less complex, and the process controls a single property (connection reliability or conductivity), offering high controllability and improving production efficiency and yield.

[0112] The following example illustrates some embodiments of the present disclosure using a light-emitting device 20 comprising two stacked light-emitting units 210, wherein the two stacked light-emitting units 210 are a first light-emitting unit 211 and a second light-emitting unit 212, respectively. However, the implementation of the present disclosure is not limited thereto, and may also include 3, 4 or more light-emitting units 210, as long as the same technical concept is applied.

[0113] In some embodiments, as shown in Figures 7, 8, 10 and 11, the light-emitting device 20 further includes a first barrier layer 26, which covers the conductive pattern 25 and the exposed surfaces of the plurality of light-emitting units 210 near the conductive pattern 25, so as to provide insulation protection and 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 Figures 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 other embodiments, as shown in Figures 8 and 11, the light-emitting device 20 further includes a second barrier layer 27 disposed between the conductive pattern 25 and the light-emitting unit 210. The second barrier layer 27 has a first connection hole 271 and a second connection hole 272, and the conductive pattern 25 extends into the first connection hole 271 and the second connection hole 272, respectively making electrical contact with 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.

[0117] It should be noted that the shapes of the first connecting hole 271 and the second connecting hole 272 can be strip-shaped or frame-shaped, and the embodiments disclosed herein are not limited to these.

[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 there is a defect in the sidewall of the first semiconductor layer 21-2 of the second light-emitting unit 212, the conductive pattern 25 is formed on the second barrier layer 27, and the adhesion is good, which is conducive to the formation of the conductive pattern 25. In addition, the conductivity between 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] Based on this, as shown in Figures 8 and 11, the first blocking layer 26 may include, for example, a first sub-part 261 and a second sub-part 262. The first sub-part 261 covers the exposed surface of the plurality of light-emitting units 210 near the conductive pattern 25, and the second sub-part 262 covers the conductive pattern 25. Furthermore, the thickness of the first sub-part 261 is greater than the thickness of the second sub-part 262.

[0121] Here, as shown in Figure 8, the first sub-part 261 may 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 near 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. Furthermore, the first sub-layer 2611 may be made of 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 may be prepared in the same process step as the second sub-part 262, which simplifies the process flow and improves production efficiency.

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

[0123] The thickness of the second sub-part 262 can be 1 μm to 2 μm. For example, the thickness of the second sub-part 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 FIG6, the conductive pattern 25 includes a first overlapping portion 251, a second overlapping portion 252, and a first connecting portion 253. The first overlapping portion 251 is disposed on the second semiconductor layer 23-1 of the first light-emitting unit 211, the second overlapping portion 252 is disposed on the first semiconductor layer 21-2 of the second light-emitting unit 212, and the first connecting portion 253 is disposed between the first overlapping portion 251 and the second overlapping portion 252, with one end connected to the first overlapping portion 251 and the other end connected to the second overlapping portion 252.

[0125] Based on this, as shown in Figure 6, in the first cross-section, the length D1 of the first overlapping portion 251 and / or the second overlapping portion 252 is greater than or equal to 1 μm, so that the first overlapping portion 251 can form a good conductive contact with the corresponding second semiconductor layer 23-1, and the second overlapping portion 252 can form a good conductive contact with the corresponding first semiconductor layer 21-2. The first cross-section is perpendicular to the plane containing the first semiconductor layer 21-2 and also perpendicular to the boundary where the first semiconductor layer 21-2 contacts the second overlapping portion 252.

[0126] Here, during the fabrication of the first overlapping portion 251 and the second overlapping portion 252, the process precision of both the etching process and the bonding process can be considered comprehensively. The designed overlap length of the first overlapping portion 251 and the second overlapping portion 252 should have a difference greater than or equal to 1 μm from the sum of the process precisions of the etching process and 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. In this case, the designed overlap length of the first overlapping portion 251 and the second overlapping portion 252 can be greater than or equal to 4 μm.

[0127] The distance D2 between the boundary of the first overlapping portion 251 and the boundary of the second semiconductor layer 23 of the connected first light-emitting unit 211 is 0μm to 5μm, so as to avoid the problem of short circuit caused by the first overlapping portion 251 connecting to the first semiconductor layer 21 on the lower side of the corresponding second semiconductor layer 23.

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

[0129] In some embodiments, referring to FIG6, 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°. Exemplarily, 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 disclosed herein are not limited thereto.

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

[0131] Figure 12 is a graph showing the relationship between luminous efficiency and current for three light-emitting devices according to some embodiments. Figure 12 shows optimizations performed on light-emitting devices A, B, and C in different current ranges. Specifically, the light-emitting units 210 of the same light-emitting device 20 are of the same type, while the light-emitting units 210 of different light-emitting devices 20 are of different types; that is, the types of light-emitting units 210 included in light-emitting devices A, B, and C are different.

[0132] It should be noted that "same type" means that the peak current value corresponding to the luminous efficiency of the light-emitting unit 210 is approximately equal, while "different type" means the opposite.

[0133] As shown in Figure 12, the peak current values ​​corresponding to the luminous efficiency of light-emitting devices A, B and C are very different. It is impossible to make the luminous efficiency of light-emitting device 20 high across the entire grayscale by using any one of the light-emitting devices 20.

[0134] Figure 13 shows the relationship between luminous efficiency and current for two light-emitting units in the same light-emitting device according to some embodiments. Figure 13 optimizes the luminous efficiency of light-emitting units D and E in the same light-emitting device 20 across the entire operating current range in grayscale. Light-emitting units D and E are of different types.

[0135] As shown in Figure 13, the peak current values ​​corresponding to the luminous efficiency of light-emitting unit D and light-emitting unit E are different. The luminous efficiencies of light-emitting unit D and light-emitting unit E compensate for each other, which can make the light-emitting device 20 have higher luminous efficiency in a larger current range and the change in luminous efficiency is relatively gradual.

[0136] Based on this, referring to Figures 11 and 13, in some embodiments of the light-emitting device 20 provided in this disclosure, the peak current values ​​corresponding to the luminous efficiency of at least two light-emitting units 210 in the light-emitting device 20 are not equal. With this configuration, the two light-emitting units 210 with unequal peak current values ​​corresponding to the luminous efficiency can achieve higher luminous efficiency across the entire grayscale through differential compensation, resulting in a smoother change in luminous efficiency across the entire grayscale.

[0137] For example, two light-emitting units 210 with different peak current values ​​corresponding to the luminous efficiency may have different luminous efficiencies at low gray levels, with one having lower luminous efficiency and the other having higher luminous efficiency; at high gray levels, one having lower luminous efficiency and the other having higher luminous efficiency. This makes the luminous efficiency of the light-emitting device 20 more stable across the entire gray level, thereby reducing the difficulty of algorithm correction.

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

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

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

[0141] In some embodiments, as shown in Figures 6 and 13, the light-emitting device 20 includes two light-emitting units 210. The ratio of the current value corresponding to the peak luminous efficiency of one light-emitting unit 210 to the current value corresponding to the peak luminous efficiency of the other is 5 to 20. For example, the current value corresponding to the peak luminous efficiency of one unit is 0.03 mA, and the current value corresponding to the peak luminous efficiency of the other unit is 0.3 mA. In this case, by compensating for the luminous efficiency of different light-emitting units 210, the light-emitting device 20 can achieve a high luminous efficiency across the entire grayscale, with a relatively smooth change.

[0142] It should be understood that the current value corresponding to the peak luminous 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. The embodiments disclosed herein are not limited thereto.

[0143] Figure 14 is a comparison of the peak luminous efficiency current and peak luminous efficiency of the light-emitting device according to some embodiments under different luminous areas. As shown in Figure 14, the peak luminous efficiency current has a roughly linear relationship with the luminous area. When the luminous area decreases from 1600 μm² (e.g., 40 μm * 40 μm) to 225 μm² (e.g., 15 μm * 15 μm), the peak luminous efficiency current decreases by approximately 60%. Thus, the luminous area of ​​the multiple luminous units 210 in the light-emitting device 20 can be set based on the linear relationship between the peak luminous efficiency current and the luminous area, and the desired brightness.

[0144] Furthermore, as shown in Figure 14, the current value corresponding to the peak luminous efficiency of the light-emitting unit 210 can be shifted to the left (reduced) by reducing the light-emitting area of ​​the light-emitting unit 210. For example, when 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 luminous efficiency of the light-emitting unit 210.

[0145] It should be noted that, based on the relationship between peak luminous efficiency and luminous area, when the decrease in peak luminous efficiency is less than or equal to 10%, the luminous area of ​​luminous unit 210 can be reduced to adjust the current value corresponding to the peak luminous efficiency of luminous unit 210, so that the current value corresponding to the peak luminous efficiency can be adjusted even when the luminous efficiency decreases slightly.

[0146] In some embodiments, as shown in Figures 5 and 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 specifically adjusted by adjusting the overlap and overlap area of ​​the conductive pattern 40; however, this embodiment is not limited to this.

[0147] In some embodiments, referring to Figures 7 and 8, the light-emitting device 20 further includes a first electrode 281, which is disposed on the upper surface of the uppermost second semiconductor layer 23. The first electrode 281 may, for example, be bonded to a driving backplane 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. A transparent metal oxide is defined as a metal oxide with a light transmittance greater than or equal to 90%. For example, 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 vertically mounted structure. Furthermore, the light-emitting device 20 can be a Micro LED, and the radial length of the orthographic projection of the light-emitting device 20 onto the driving backplate 10 can be 30μm to 40μm. Based on this, after multiple light-emitting devices 20 are mass-transferred to the driving backplate 10, the first semiconductor layer 21 of the multiple light-emitting devices 20 furthest from the first electrode 281 can be connected to the driving backplate 10 through a second electrode layer and wiring to receive the second power signal. Simultaneously, in the vertically mounted light-emitting device 20, the lowermost light-emitting unit 210 does not require a second electrode; therefore, the light-emitting area of ​​its upper adjacent light-emitting unit 210 can reach 80% of the light-emitting area of ​​the lowermost light-emitting unit 210.

[0150] In other embodiments, referring to Figures 10 and 11, the light-emitting device 20 further includes 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 may be bonded to the driving backplate 10, for example, to receive a first power signal. The second electrode 282 is disposed on the upper surface of the lowermost first semiconductor layer 21 extending beyond the edge of the light-emitting layer 22, and the second electrode 282 may also be bonded to the driving backplate 10, for example, 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 together, with the second sub-electrode 2822 located above the first sub-electrode 2821. The first sub-electrode 2821 is used to reduce contact resistance, and the second sub-electrode 2822 is used to improve welding yield. Figures 10 and 11 illustrate the second electrode 282 as including the first sub-electrode 2821 and the second sub-electrode 2822, but the embodiments disclosed are not limited to this.

[0152] It should be noted that the materials of the first electrode 281 and the second electrode 282 include transparent metal oxides. A transparent metal oxide is defined as 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 has a flip-chip structure. Furthermore, 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 orthogonal projection of the light-emitting device 20 onto the driving backplate 10 can be 30μm to 50μm.

[0154] It should be noted that when the light-emitting device 20 is a flip-chip structure, the light-emitting device 20 may also include a first substrate 110, and a plurality of light-emitting units 210 are stacked sequentially on the first substrate 110.

[0155] In some examples, referring to Figures 9, 15, 16 and 17, the orthographic projection of the first semiconductor layer 21 onto the reference plane is rectangular, and the reference plane is the plane where the bottommost first semiconductor layer 21 is located.

[0156] Based on this, in the light-emitting unit 210 located at the bottom, the light-emitting layer 22 exposes a corner region S of the first semiconductor layer 21, and the second electrode 282 is disposed in the corner region S. This helps to reduce the clearance 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.

[0157] It should be noted that the boundary of the corner area S can be, for example, arc-shaped, to further reduce the clearance 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 FIG15, in the orthographic projection onto the reference plane, along the second direction Y, the second electrode 282 is located on one side of the first semiconductor layer 21-2 of the second light-emitting unit 212. Furthermore, the conductive pattern 25 covers the first boundary L1 of the corresponding first semiconductor layer 21-2 of the 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 region M shown in FIG15, with the effective light-emitting area being 1 / 4 of the light-emitting area.

[0159] In some examples, as shown in Figure 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. Furthermore, the conductive pattern 25 covers the second boundary L2 of the corresponding first semiconductor layer 21-2 of the second light-emitting unit 212. In this case, most of the current flows from the second boundary L2 to the second electrode 282, and the effective light-emitting region can be considered as region N shown in Figure 16, with the effective light-emitting area being 1 / 4 of the total light-emitting area.

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

[0161] In some examples, as shown in FIG17, in the orthographic projection onto the reference plane, along the second direction Y, the second electrode 282 is located on one side of the first semiconductor layer 21-2 of the second light-emitting unit 212. Furthermore, 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] Based on this, 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, a portion of the current flows from the first boundary L1 to the second electrode 282, and a portion of the current flows from the second boundary L2 to the second electrode 282. The effective light-emitting area can be considered as the T region shown in Figure 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 boundaries of the first semiconductor layer 21-2 of the corresponding second light-emitting unit 212, since the first boundary L1 and the second boundary L2 are close to the second electrode 282, most of the current will still flow from the first boundary L1 and the second boundary L2 to the second electrode 282. Therefore, by having the conductive pattern 25 cover only the first boundary L1 and / or the second boundary L2, the manufacturing cost can be reduced without significantly decreasing the effective light-emitting area.

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

[0165] In addition, when the light-emitting device 20 includes 3, 4 or more light-emitting units 210, the conductive pattern 25 may only cover the first boundary L1 and / or the second boundary L2, so as to reduce the light-blocking area of ​​the conductive pattern 25 and improve the light-emitting efficiency without significantly reducing the effective light-emitting area.

[0166] In some other embodiments, as shown in FIG18, 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 Figure 18, a conductive substrate 291 is disposed on the upper side (lower side in Figure 18) of the plurality of light-emitting units 210 to provide support. A conductive bonding layer 292 may be disposed between the conductive substrate 291 and the plurality of light-emitting units 210 to bond the conductive substrate 291 to the plurality of light-emitting units 210.

[0168] Furthermore, the first electrode 281 is disposed on the side of the first semiconductor layer 21 furthest from the conductive substrate 291, away from the conductive substrate 291; the first electrode 281 may be bonded to the driving backplate 10, for example, to receive a first power signal. The second electrode 282 is disposed on the side of the conductive substrate 291 furthest from the plurality of light-emitting units 210, and the second electrode 282 may cover the entire conductive substrate 291, for example; the second electrode 282 may be connected to the driving backplate 10 via a wire, for example, to receive a second power signal.

[0169] At this time, the light-emitting device 20 can be a vertically mounted structure. Furthermore, the light-emitting device 20 can be a Mini LED, and the radial length of the orthographic projection of the light-emitting device 20 onto the driving backplate 10 can be greater than or equal to 50 μm. Based on this, multiple light-emitting devices 20 can be individually transferred to the driving backplate 10 for die bonding.

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

[0171] Some embodiments of this disclosure also provide a method for fabricating a light-emitting device 20, as shown in FIG19, the method comprising steps S100 to S200.

[0172] S100: Forms multiple light-emitting units 210 and an adhesive layer 24.

[0173] In the above steps, multiple light-emitting units 210 are stacked sequentially, and an adhesive layer 24 is disposed between two adjacent light-emitting units 210 to bond and fix the two light-emitting units 210 together.

[0174] The light-emitting area of ​​the lower light-emitting unit 210 is larger than that of the upper light-emitting unit 210. Each light-emitting unit 210 includes a first semiconductor layer 21, a light-emitting layer 22, and a second semiconductor layer 23 stacked sequentially, with at least a portion of the edge of the first semiconductor layer 21 extending beyond the light-emitting layer 22. Furthermore, two adjacent light-emitting units 210 are respectively a first light-emitting unit 211 and a second light-emitting unit 212, with at least a portion of the edge of the second semiconductor layer 23-1 of the first light-emitting unit 211 extending beyond the first semiconductor layer 21-2 of the second light-emitting unit 212.

[0175] In some embodiments, as shown in FIG20, S100 includes S110 to S140.

[0176] Figures 21 to 24 are step diagrams illustrating the fabrication process of a vertically mounted light-emitting device according to some embodiments; Figures 25 to 29 are step diagrams illustrating the fabrication process of a flip-chip light-emitting device according to some embodiments.

[0177] S110: As shown in Figures 21 and 25, a first light-emitting unit 211 is formed on the first substrate 110.

[0178] In the above steps, a first semiconductor thin film 21', a light-emitting thin film 22', and a second semiconductor thin film 23' can be sequentially grown on the first substrate 110 using a growth process. 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 spaced-apart first light-emitting units 211 using an etching process, and the light-emitting layer 22 and the second semiconductor layer 23 are recessed relative to the first semiconductor layer 21, forming a step. It should be noted that the first substrate 110 can be any of a sapphire substrate, a silicon substrate, and a gallium arsenide substrate, and the embodiments disclosed herein are not limited to these.

[0179] S120: As shown in Figures 22 and 26, a second light-emitting unit 212 is formed on the second substrate 120.

[0180] In the above steps, a first semiconductor thin film 21', a light-emitting thin film 22', and a second semiconductor thin film 23' can be sequentially grown on the second substrate 120 using a growth process. Then, an etching process is used to divide the first semiconductor thin film 21', the light-emitting thin film 22', and the second semiconductor thin film 23' into a plurality of spaced-apart second light-emitting units 212, such that the light-emitting layer 22 and the second semiconductor layer 23 are recessed relative to the first semiconductor layer 21, forming 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 of a sapphire substrate, a silicon substrate, and a gallium arsenide substrate, and the embodiments disclosed herein are not limited to this. In addition, the order of S110 and S120 is not fixed. S110 can be performed first, followed by S120; or S120 can be performed first, followed by S110; or S110 and S120 can be performed simultaneously.

[0182] S130: As shown in Figures 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 means of temporary bonding adhesive 30, and the second substrate 120 is removed.

[0183] In the above steps, the second substrate 120 can be removed by any of the following processes: mechanical polishing, mechanical peeling, and etching. Furthermore, the temporary bonding adhesive 30 is made of resin and / or polydimethylsiloxane to facilitate subsequent processes in separating the third substrate 130 from the second light-emitting unit 212. It should be noted that the third substrate 130 can be any of a sapphire substrate, a silicon substrate, a glass substrate, and a gallium arsenide substrate; the embodiments disclosed herein are not limited to these.

[0184] S140: As shown in Figures 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 through 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 by coating or printing processes, or on the side of the first light-emitting unit 211 away from the first substrate 110. Furthermore, the third substrate 130 can be removed by any of the following processes: mechanical polishing, mechanical peeling, and etching. For example, the third substrate 130 can be removed by laser dissociation, thereby removing the temporary bonding adhesive 30 and the third substrate 130.

[0186] When the light-emitting device 20 is a flip-chip structure, between S110 and S130, referring to Figures 29 and 30, S100 also includes S150.

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

[0188] In the above steps, the first sub-electrode 2821 is disposed on the upper surface of the portion of the first semiconductor layer 21 that extends beyond the edge of the light-emitting layer 22, i.e., the first sub-electrode 2821 is disposed on the step to reduce contact resistance. The first sub-electrode 2821 can be formed using a mask and a vapor deposition process; however, this embodiment is not limited to this.

[0189] In this case, after the first light-emitting unit 211 is fabricated, the first sub-electrode 2821 directly contacts the first semiconductor layer 21. This can avoid over-etching or incomplete removal of other films (such as the second barrier layer 282) in the future, which would result in poor conductive connection between the first sub-electrode 2821 and the first semiconductor layer 21.

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

[0191] In the above steps, the conductive pattern 25 is connected to two adjacent light-emitting units 210. A portion of the conductive pattern 25 makes electrical contact with the edge of the second semiconductor layer 23-1 of the first light-emitting unit 211 extending beyond the first semiconductor layer 21-2 of the second light-emitting unit 212, and another portion makes electrical contact with the edge of the first semiconductor layer 21-2 of the second light-emitting unit 212 extending beyond the light-emitting layer 22-2. The conductive pattern 25 can be formed using a mask and a vapor deposition process; however, this embodiment is not limited to this method.

[0192] In some embodiments, as shown in FIG33, S300 is included before S200.

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

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

[0195] Based on this, referring to Figure 11, the conductive pattern 25 extends into the first connecting hole 271 and the second connecting hole 272, making electrical contact with the first semiconductor layer 21-2 and the second semiconductor layer 23-1, respectively. Furthermore, the second barrier layer 27 is the portion 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 FIG33, after S200, the above preparation method further includes S400.

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

[0198] In the above steps, the first barrier film 26' covers the conductive pattern 25 and the exposed surfaces of the first light-emitting unit 211 and the second light-emitting unit 212 near the conductive pattern 25. At this time, the first barrier layer 26 is the portion of the first barrier film 26' and the second barrier film 27' located outside the conductive pattern 25.

[0199] After forming the first barrier film 26', a first via (not shown in Figures 36 and 37) can be formed in the first barrier film 26'. The first via exposes the second semiconductor layer 23-2 of the second light-emitting unit 212 to facilitate the formation of the first electrode 281 in subsequent processes. Furthermore, if the light-emitting device 20 has a flip-chip structure, a second via (not shown in Figure 37) can be formed in the first barrier film 26'. The second via exposes the first sub-electrode 2821 to facilitate the formation of the second sub-electrode 2822 in subsequent processes (see Figure 43).

[0200] When the light-emitting device 20 is a vertically mounted structure, and the light-emitting device 20 can be transferred to the driving backplate 10 in large quantities, and then connected to the driving backplate 10 through the second electrode layer and wiring to receive the second power signal, such as when the light-emitting device 20 is a Micro LED, as shown in Figure 33, after S400, the above-mentioned preparation method also includes S500.

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

[0202] In the above steps, the first electrode 281 extends into the first via and makes electrical contact with the second semiconductor layer 23-2 to provide a first power signal. The first electrode 281 can be formed using a mask and a vapor deposition process; however, this embodiment is not limited to this.

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

[0204] When the light-emitting device 20 is a vertically mounted structure and the light-emitting device 20 can be transferred separately to the driving backplate 10 for die bonding, such as when the light-emitting device 20 is a Mini LED, after 400, as shown in FIG39, the above preparation method further includes S610 to S620.

[0205] S610: As shown in FIG40, the conductive substrate 291 is connected to the side of the second light-emitting unit 212 away from the first substrate 110 through 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 polishing, mechanical stripping, and etching processes. Furthermore, the conductive bonding layer 292 includes conductive adhesive, and the conductive substrate 291 can be a silicon substrate.

[0207] S620: As shown in Figure 41, a first electrode 281 and a 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 furthest from the conductive substrate 291, and the second electrode 282 is disposed on the side of the conductive substrate 291 furthest from the plurality of light-emitting units 210. The first electrode 281 and the second electrode 282 can be formed using a mask and a vapor deposition process; however, this embodiment is not limited to this.

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

[0210] When the light-emitting device 20 is a flip-chip structure, as shown in Figure 42, after S400, the above-mentioned preparation method also includes S700.

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

[0212] In the above steps, the first electrode 281 extends into the first via and makes electrical contact with 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 semiconductor layer 21-1 away from the first sub-electrode 2821 and is in electrical contact with 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 using a mask and a vapor deposition process, but the embodiments disclosed in this disclosure are not limited thereto.

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

[0214] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0215] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the 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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