Display unit, preparation method thereof and display device

Abstract

The invention discloses a display unit, a preparation method thereof and a display device. The display unit comprises at least two stacked light-emitting units, and the wavelengths of light emitted by the at least two light-emitting units are different; the display unit further comprises a periodic structure, and the periodic structure is arranged between every two adjacent light-emitting units. The periodic structure comprises a first bonding layer and a second bonding layer which are stacked and have different refractive indexes, and the periodic structure is used for bonding the corresponding light-emitting units, reflecting emergent light of the light-emitting units close to one side of the light-emitting surface and transmitting emergent light of the light-emitting units away from one side of the light-emitting surface. The structure of the display unit can be simplified.

Description

Technical Field

[0001] The present invention relates to the field of display technologies, and particularly to a display unit, a preparation method thereof, and a display device. Background Art

[0002] A display unit can emit lights of multiple colors, and a display device for emitting light or for display can be formed by arranging the display units on a substrate.

[0003] However, in related technologies, the structure of the display unit is complex, which makes the manufacturing process relatively complex, and further makes the cost of the display unit relatively high, restricting the further application of the display unit. Summary of the Invention

[0004] The present invention provides a display unit, a preparation method thereof, and a display device to simplify the structure of the display unit.

[0005] According to one aspect of the present invention, a display unit is provided, which includes at least two stacked light-emitting units that emit lights with different wavelengths;

[0006] The display unit further includes a periodic structure disposed between two adjacent light-emitting units; the periodic structure includes a first adhesive layer and a second adhesive layer that are stacked and have different refractive indices, and the periodic structure is used for bonding the corresponding light-emitting units, reflecting the outgoing light of the light-emitting unit closer to the light-emitting surface, and transmitting the outgoing light of the light-emitting unit farther from the light-emitting surface.

[0007] Optionally, one such periodic structure is disposed between any two adjacent light-emitting units.

[0008] Optionally, the at least two light-emitting units include a first light-emitting unit and a second light-emitting unit, and the periodic structure is disposed between the first light-emitting unit and the second light-emitting unit;

[0009] Alternatively, the at least two light-emitting units include a first light-emitting unit, a second light-emitting unit, and a third light-emitting unit, a first periodic structure is disposed between the first light-emitting unit and the second light-emitting unit, and a second periodic structure is disposed between the second light-emitting unit and the third light-emitting unit.

[0010] Optionally, the materials of the first adhesive layer and the second adhesive layer are different.

[0011] Optionally, at least one of the first adhesive layer and the second adhesive layer includes an adhesive material and a doping material.

[0012] Optionally, the adhesive material is an optical adhesive.

[0013] Optionally, the light-emitting unit includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer that are stacked, and the types of the first semiconductor layer and the second semiconductor layer are different.

[0014] According to another aspect of the present invention, there is provided a method for manufacturing a display unit, the display unit including the display unit as described above; the method for manufacturing the display unit includes:

[0015] Form at least two light-emitting units, and the light-emitting wavelengths of different types of light-emitting units are different;

[0016] Form the periodic structure to bond two light-emitting units to be bonded, wherein the periodic structure is further configured to reflect the light emitted by one of the light-emitting units and transmit the light emitted by the other light-emitting unit.

[0017] Optionally, the forming the periodic structure to bond different light-emitting units includes:

[0018] Form the periodic structure on one of the light-emitting units to be bonded;

[0019] Bond the other light-emitting unit to the periodic structure.

[0020] According to another aspect of the present invention, there is provided a display device, the display device including a substrate and a plurality of display units as described above; wherein, the display device is formed by transferring the display units to the substrate in a large quantity.

[0021] The technical solution of the embodiment of the present invention adopts a display unit including at least two stacked light-emitting units, and the light wavelengths emitted by the at least two light-emitting units are different; the display unit further includes a periodic structure, and the periodic structure is disposed between two adjacent light-emitting units; the periodic structure includes a first bonding layer and a second bonding layer that are stacked and have different refractive indexes, and the periodic structure is used to bond the corresponding light-emitting units, reflect the outgoing light of the light-emitting unit close to the light-emitting surface side, and transmit the outgoing light of the light-emitting unit far from the light-emitting surface side. By providing the periodic structure, the periodic structure not only has the function of a Bragg reflection layer but also has the bonding function, so that the structural complexity of the display unit is relatively low. At the same time, when manufacturing, the periodic structure can be directly combined with the light-emitting unit to form the display unit, without adding other bonding structures, thus greatly simplifying the manufacturing process of the display unit.

[0022] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0024] Figure 1 Schematic structural diagram of a display unit provided by an embodiment of the present invention;

[0025] Figure 2 Schematic structural diagram of another display unit provided by an embodiment of the present invention;

[0026] Figure 3 Schematic structural diagram of another display unit provided by an embodiment of the present invention;

[0027] Figure 4 Schematic structural diagram of another display unit provided by an embodiment of the present invention;

[0028] Figure 5 Flowchart of a preparation method of a display unit provided by an embodiment of the present invention;

[0029] Figure 6 Schematic structural diagram of a product formed corresponding to the main steps of a preparation method of a display unit provided by an embodiment of the present invention;

[0030] Figure 7 Schematic structural diagram of a product formed corresponding to the main steps of another preparation method of a display unit provided by an embodiment of the present invention;

[0031] Figure 8 Schematic structural diagram of a display device provided by an embodiment of the present invention. Detailed implementation manners

[0032] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily limit to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0034] An embodiment of the present invention provides a display unit. The display unit includes at least two stacked light-emitting units, and the wavelengths of the light emitted by the at least two light-emitting units are different, that is, the wavelengths of the light emitted by different light-emitting units in the same display unit are different; the display unit further includes a periodic structure, and the periodic structure is disposed between two adjacent light-emitting units; the periodic structure includes a first adhesive layer and a second adhesive layer which are stacked and have different refractive indexes, and the periodic structure is used to bond the corresponding light-emitting units, reflect the outgoing light of the light-emitting unit close to the light-emitting surface side, and transmit the outgoing light of the light-emitting unit far from the light-emitting surface side.

[0035] Specifically, the light-emitting unit can be a Micro-LED (Micro Light Emitting Diode). Each display unit contains at least two stacked light-emitting units, and the light-emitting wavelengths of each light-emitting unit are different, that is, the light-emitting colors of different light-emitting units are different, and the light emitted by different light-emitting units is mixed to form light of the corresponding color. That is, by stacking at least two light-emitting units with different light-emitting colors, the display unit can realize outgoing light of multiple colors. More typically, the display unit can stack three different light-emitting units, namely a red light-emitting unit, that is, a light-emitting unit with red outgoing light; a green light-emitting unit, that is, a light-emitting unit with green outgoing light; and a blue light-emitting unit, that is, a light-emitting unit with blue outgoing light. By stacking three different light-emitting units, the display unit can realize various color displays.

[0036] After the Micro-LEDs are fabricated, they need to be transferred to a substrate through a mass transfer process. Among them, a pixel driving circuit corresponding to the Micro-LEDs is provided on the substrate, and the display of each light-emitting unit in the display unit is realized through the pixel driving circuit. In related technologies, if each display unit only includes one light-emitting unit, in order to achieve full-color display, light-emitting units of various light-emitting colors need to be transferred to the substrate through multiple mass transfer processes. By setting the display unit to stack at least two light-emitting units, on the one hand, the number of mass transfer processes can be reduced, thereby reducing the workload and process time, and thus reducing costs. On the other hand, the pixels composed of the display units also occupy a smaller area of the substrate, which is also beneficial to increasing the pixel density.

[0037] In this embodiment, the display unit is further provided with a periodic structure. The periodic structure can reflect the outgoing light of the light-emitting unit close to the light-emitting surface side and transmit the outgoing light of the light-emitting unit far from the light-emitting surface side. One side of the periodic structure is the side close to the light-emitting surface of the display unit, and the other side is the side far from the light-emitting surface of the display unit. In other words, for the light-emitting unit located on the side of the periodic structure close to the light-emitting surface, the light emitted by this light-emitting unit along the direction away from the light-emitting surface of the display panel will be reflected by the periodic structure and then emitted through the light-emitting surface of the display unit, which can improve the light-emitting efficiency of this light-emitting unit. In addition, the periodic structure can transmit the outgoing light of the light-emitting unit located on the side far from the light-emitting surface of the display unit, so it will not reduce the light-emitting efficiency of other light-emitting units. The periodic structure includes a first adhesive layer and a second adhesive layer stacked. The periodic structure can include multiple layers of the first adhesive layer and multiple layers of the second adhesive layer, and a Bragg reflection layer is formed by alternately arranging them. The Bragg reflection layer can reflect light of its working wavelength and transmit light of other wavelengths. Typically, the working wavelength of the Bragg reflection layer can be adjusted by adjusting at least one of the thickness of the first adhesive layer, the refractive index of the first adhesive layer, the thickness of the second adhesive layer, and the refractive index of the second adhesive layer.

[0038] In addition, in this embodiment, the periodic structure can not only form a Bragg reflection layer, but also bond the corresponding light-emitting units due to its adhesive function. That is, the periodic structure has two functions. Compared with realizing the above two functions through two different functional layers, the structure of the display unit can be simplified and the thickness of the display unit can be reduced. When fabricating the display unit, it is necessary to first fabricate each light-emitting unit, and then combine the light-emitting units to form a display unit. In this embodiment, by setting the periodic structure to include a first adhesive layer and a second adhesive layer, each adhesive layer has an adhesive function. When combining the light-emitting units, by combining the periodic structure and the corresponding light-emitting units, a stable and reliable display unit can be formed. That is, a display unit with a periodic structure can be fabricated through fewer process steps, greatly simplifying the fabrication process of the display unit with a periodic structure, and thus reducing costs.

[0039] In the technical solution of this embodiment, the display unit adopted includes at least two stacked light-emitting units; the light wavelengths emitted by the at least two light-emitting units are different; the display unit further includes a periodic structure, and the periodic structure is arranged between two adjacent light-emitting units; the periodic structure includes a first adhesive layer and a second adhesive layer which are stacked and have different refractive indexes, and the periodic structure is used to bond the corresponding light-emitting units, reflect the outgoing light of the light-emitting unit close to the light-emitting surface side, and transmit the outgoing light of the light-emitting unit far from the light-emitting surface side. By arranging the periodic structure, the periodic structure not only has the function of a Bragg reflection layer but also has the function of bonding, so that the structural complexity of the display unit is relatively low. At the same time, during manufacturing, the periodic structure can be directly combined with the light-emitting units to form the display unit without adding other bonding structures, thus greatly simplifying the manufacturing process of the display unit with a periodic structure.

[0040] Certainly, when the reflection band of the periodic structure is short, or when a periodic structure is arranged between any two light-emitting units, it can be set that the periodic structure only reflects the outgoing light of the light-emitting unit adjacent to it and on the side close to the light-emitting surface of the display unit, and transmits the outgoing light of the light-emitting unit on the side far from the light-emitting surface of the display unit, so as to improve the reflection efficiency and further improve the light-emitting efficiency of the display unit.

[0041] The above is the core idea of the present invention. The following will further illustrate the present invention with reference to the drawings.

[0042] Optionally, Figure 1 is a schematic structural diagram of a display unit provided by an embodiment of the present invention, refer to Figure 1 . The display unit includes a first light-emitting unit 30 and a second light-emitting unit 50, and a periodic structure is arranged between the first light-emitting unit 30 and the second light-emitting unit 50.

[0043] Specifically, the display unit 20 of this embodiment only includes two light-emitting units, and the first light-emitting unit 30 and the second light-emitting unit 50 are stacked in sequence along the light-emitting direction X of the display unit. The first light-emitting unit 30 can be a red light-emitting unit, and at this time the second light-emitting unit 50 can be a green light-emitting unit or a blue light-emitting unit. The first light-emitting unit 30 can also be a green light-emitting unit, and at this time the second light-emitting unit 50 can be a blue light-emitting unit. The periodic structure between the first light-emitting unit 30 and the second light-emitting unit 50 is defined as the first periodic structure 40. The first adhesive layer 41 of the first periodic structure and the second adhesive layer 42 of the first periodic structure are arranged alternately. It should be noted that, Figure 1Taking the first periodic structure 40 including four first adhesive layers and four second adhesive layers as an example, but not limited thereto. The first periodic structure 40 is used to reflect the emitted light of the second light-emitting unit 50 and transmit the emitted light of the first light-emitting unit 30. At this time, the operating wavelength of the first periodic structure 40 can be set to include the wavelength of the emitted light of the second light-emitting unit 50. For example, the thicknesses of the first adhesive layer and the second adhesive layer can be set to 1 / 4 of the wavelength of the emitted light of the second light-emitting unit 50. And the reflectivity of the emitted light of the second light-emitting unit 50 can be adjusted by setting the difference value of the refractive indices of the first adhesive layer and the second adhesive layer. In addition, in some other embodiments, the stacking order of different light-emitting units in the same display unit can be arbitrary.

[0044] Optionally, Figure 2 is a schematic structural diagram of another display unit provided by an embodiment of the present invention. Refer to Figure 2 . The display unit includes a first light-emitting unit 30, a second light-emitting unit 50, and a third light-emitting unit 70 stacked in sequence along its light-emitting direction X. The first light-emitting unit 30 can be a red light-emitting unit, the second light-emitting unit 50 can be a green light-emitting unit, and the third light-emitting unit 70 can be a blue light-emitting unit. In the Figure 2 shown structure, a first periodic structure 40 is provided between the first light-emitting unit 30 and the second light-emitting unit 50. The first periodic structure 40 is used to reflect the emitted light of the second light-emitting unit 50 and transmit the emitted light of the first light-emitting unit 30. At this time, the operating wavelength of the first periodic structure 40 can be set to include the wavelength of the emitted light of the second light-emitting unit 50. For example, the thicknesses of the first adhesive layer and the second adhesive layer can be set to 1 / 4 of the wavelength of the emitted light of the second light-emitting unit 50. And the reflectivity of the emitted light of the second light-emitting unit 50 can be adjusted by setting the difference value of the refractive indices of the first adhesive layer and the second adhesive layer.

[0045] Of course, it should be noted that Figure 2 the second light-emitting unit 50 and the third light-emitting unit 70 in

[0046] Optionally, Figure 3 is a schematic structural diagram of another display unit provided by an embodiment of the present invention. Refer to Figure 3 . Compared with Figure 2In contrast to the above, in this embodiment, a second periodic structure 60 is provided between the second light-emitting unit 50 and the third light-emitting unit 70. The second periodic structure 60 is used to reflect the outgoing light of the third light-emitting unit 70 and transmit the outgoing lights of the second light-emitting unit 50 and the first light-emitting unit 30. At this time, the operating wavelength of the second periodic structure 60 can be set to include the wavelength of the outgoing light of the third light-emitting unit 70. For example, the thicknesses of the first adhesive layer 61 of the second periodic structure and the second adhesive layer 62 of the second periodic structure can be set to 1 / 4 of the wavelength of the outgoing light of the third light-emitting unit 70. And the reflectivity of the outgoing light of the third light-emitting unit 70 can be adjusted by setting the difference value of the refractive indices of the first adhesive layer and the second adhesive layer.

[0047] Optionally, a periodic structure is provided between any two adjacent light-emitting units. Figure 4 This is a schematic structural diagram of another display unit provided by an embodiment of the present invention. Refer to Figure 4 . Different from Figure 2 and Figure 3 in this embodiment, a first periodic structure 40 is provided between the first light-emitting unit 30 and the second light-emitting unit 50. The first periodic structure 40 is used to reflect the outgoing light of the second light-emitting unit 50 and transmit the outgoing light of the first light-emitting unit 30. At this time, the operating wavelength of the first periodic structure 40 can be set to include the wavelength of the outgoing light of the second light-emitting unit 50. For example, the thicknesses of the first adhesive layer and the second adhesive layer can be set to 1 / 4 of the wavelength of the outgoing light of the second light-emitting unit 50. And the reflectivity of the outgoing light of the second light-emitting unit 50 can be adjusted by setting the difference value of the refractive indices of the first adhesive layer and the second adhesive layer. A second periodic structure 60 is provided between the second light-emitting unit 50 and the third light-emitting unit 70. The second periodic structure 60 is used to reflect the outgoing light of the third light-emitting unit 70 and transmit the outgoing lights of the second light-emitting unit 50 and the first light-emitting unit 30. At this time, the operating wavelength of the second periodic structure 60 can be set to include the wavelength of the outgoing light of the third light-emitting unit 70. For example, the thicknesses of the first adhesive layer 61 of the second periodic structure and the second adhesive layer 62 of the second periodic structure can be set to 1 / 4 of the wavelength of the outgoing light of the third light-emitting unit 70. And the reflectivity of the outgoing light of the third light-emitting unit 70 can be adjusted by setting the difference value of the refractive indices of the first adhesive layer and the second adhesive layer. In this embodiment, by providing a periodic structure between any two adjacent light-emitting units, the light extraction efficiency of more light-emitting units can be improved, and thus the light extraction efficiency of the display unit can be improved to a greater extent.

[0048] Optionally, in the above embodiments, the materials of the first adhesive layer and the second adhesive layer are different. By setting different materials, the refractive indices of the adhesive layers are controlled to be different. For example, the material of the first adhesive layer is one type of optical adhesive, and the material of the second adhesive layer is another type of optical adhesive. Optical adhesives, such as OCA (Optically Clear Adhesive) optical adhesives, are special adhesives used for transparent optical elements. Mainly, optical acrylic adhesives are made into substrate-free, and then a release film is laminated on each of the upper and lower layers to form a substrate-free high-transparency double-sided adhesive film, which has advantages such as high cleanliness, high light transmittance, low haze, high adhesion, no crystal points, no bubbles, water resistance, high temperature resistance, and ultraviolet resistance. It will not cause problems such as yellowing, aging, fogging, detachment from the adhered surface, and generation of bubbles after long-term use. Optical adhesives are selected from, for example, epoxy resins, polyimides, SU8 photoresists, spin-coated glass, and benzocyclobutene BCB.

[0049] Optionally, in some other embodiments, at least one of the first adhesive layer and the second adhesive layer includes an adhesive material and a doping material. It can be set that the first adhesive layer and the second adhesive layer include the same adhesive material and different doping materials. By doping different doping materials in the adhesive material, the first adhesive layer and the second adhesive layer with different refractive indices are realized. The adhesive material can be one of the above optical adhesives, and the doping material is, for example, a metal or other impurities, etc.

[0050] Optionally, as Figures 1 to 4 shown, the light-emitting unit includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer stacked, and the types of the first semiconductor layer and the second semiconductor layer are different.

[0051] Specifically, in each light-emitting unit, one of the first semiconductor layer and the second semiconductor layer is an n-type semiconductor layer, and the other is a p-type semiconductor layer. When a forward voltage is applied to the light-emitting unit, the electrons generated in the n-type semiconductor layer and the holes generated in the p-type semiconductor layer recombine in the light-emitting layer to achieve light emission. The light-emitting layer is, for example, a quantum well layer, and different wavelengths of emitted light are realized through different light-emitting layers. In addition, the n-type semiconductor layer can be achieved by n-type doping. For example, silicon is doped in gallium nitride material, and tetravalent silicon replaces trivalent gallium to generate electrons; the p-type semiconductor layer can be achieved by p-type doping. For example, magnesium is doped in gallium nitride material, and divalent magnesium replaces trivalent gallium to generate holes.

[0052] Exemplarily, the first light-emitting unit 30 includes a first first semiconductor layer 31, a first light-emitting layer 33, and a first second semiconductor layer 32. The second light-emitting unit 50 includes a second first semiconductor layer 51, a second light-emitting layer 52, and a second second semiconductor layer 55. The third light-emitting unit 70 includes a third first semiconductor layer 71, a third light-emitting layer 73, and a third second semiconductor layer 75. Two semiconductor layers that are located in different light-emitting units and are adjacent to each other can be semiconductor layers of the same type or different types. For example, the first second semiconductor layer and the second first semiconductor layer can be semiconductor layers of the same type (such as both being n-type semiconductor layers or both being p-type semiconductor layers), or can be semiconductor layers of different types (such as one being an n-type semiconductor layer and the other being a p-type semiconductor layer). Of course, when both the first second semiconductor layer 35 and the second first semiconductor layer 51 are p-type semiconductor layers, an ohmic contact layer can be provided on the p-type semiconductor layer.

[0053] It can be understood that an electrode structure can also be provided between different light-emitting units. In addition, although in the figure, the transverse dimensions (widths from left to right in the figure) of each light-emitting unit are the same as an example, it is not limited thereto. For example, the transverse dimension of the first light-emitting unit can be greater than the transverse dimension of the second light-emitting unit, and the transverse dimension of the second light-emitting unit can be greater than the transverse dimension of the third light-emitting unit. When the transverse dimensions of different light-emitting units are different, the transverse dimension of the periodic structure is set to be greater than or equal to the transverse dimension of the light-emitting unit that is adjacent to it and is located on the side close to the light-emitting surface of the display unit. Preferably, the two dimensions are equal, so that the number of film layers that the partial emitted light of the light-emitting unit located on the side of the periodic structure away from the light-emitting surface of the display unit needs to penetrate is small, and the light-emitting efficiency of this light-emitting unit can be further improved.

[0054] The present invention also provides a method for manufacturing a display unit, as Figure 5 shown, Figure 5 is a flowchart of a method for manufacturing a display unit provided by an embodiment of the present invention. The display unit is the display unit provided by any embodiment of the present invention. The method for manufacturing the display unit includes:

[0055] Step S110, forming at least two light-emitting units, and the light-emitting wavelengths of different light-emitting units are different.

[0056] Specifically, in this embodiment, at least two types of light-emitting units can be separately fabricated, and multiple light-emitting units of each type can be formed simultaneously. The forming method is well-known to those skilled in the art. For example, it is by growing an epitaxial structure and lithographing the epitaxial structure to form multiple light-emitting units. When forming different types of light-emitting units, they can be formed simultaneously in different devices, or formed at different times in the same device, or formed at different times in different devices. The growth method is well-known to those skilled in the art and will not be elaborated here.

[0057] Step S120: Form a periodic structure to bond two light-emitting units to be bonded, where the periodic structure is further configured to reflect light emitted by one of the light-emitting units and transmit light emitted by the other light-emitting unit.

[0058] Specifically, the periodic structure includes a first bonding layer and a second bonding layer, and the bonding layer has adhesiveness. When combining the light-emitting units, by combining the periodic structure and the corresponding light-emitting units, a stable and reliable display unit can be formed, that is, a display unit with a periodic structure can be fabricated through fewer process steps, greatly simplifying the preparation process and thus reducing the cost.

[0059] Optionally, Figure 6 is a schematic diagram of the product structure corresponding to the main steps of a preparation method of the display unit provided by an embodiment of the present invention, as Figure 6 shown. In this embodiment, forming a periodic structure to bond different light-emitting units includes:

[0060] Form a periodic structure on one of the light-emitting units to be bonded, and bond the other light-emitting unit to the periodic structure.

[0061] Specifically, as Figure 6 shown, taking the display unit including a first light-emitting unit 30, a second light-emitting unit 50, and a first periodic structure 40 as an example. The periodic structure 40 can be first formed on the side of the second light-emitting unit 50 away from the light-emitting surface of the display unit (i.e., the side facing away from the light-emitting direction X), and specifically, each bonding layer can be formed periodically. Preferably, when forming the bonding layer that needs to contact the first light-emitting unit, the bonding layer can be not cured first to keep it in a certain fluid state; or it can be heated to keep it in a certain fluid state to increase adhesiveness. Subsequently, the first light-emitting unit is attached to the periodic structure, and at this time, the first light-emitting unit is bonded to the corresponding bonding layer. Of course, the firmness of the bonding can also be increased by squeezing the display unit.

[0062] Optionally, Figure 7 is a schematic diagram of the product structure corresponding to the main steps of another preparation method of the display unit provided by an embodiment of the present invention, as Figure 7 shown. In this embodiment,

[0063] Still taking the display unit including the first light-emitting unit 30, the second light-emitting unit 50, and the first periodic structure 40 as an example. The periodic structure 40 can be formed on the first light-emitting unit 30 close to the light-emitting surface of the display unit (i.e., the side in the light-emitting direction X). Specifically, each adhesive layer can be formed periodically. Preferably, when forming the adhesive layer that needs to contact the second light-emitting unit, the adhesive layer can be left uncured to keep it in a certain fluid state; or it can be heated to keep it in a certain fluid state to increase its viscosity. Subsequently, the second light-emitting unit is attached to the periodic structure, and at this time, the second light-emitting unit is adhered to the corresponding adhesive layer. Of course, the firmness of the adhesion can also be increased by squeezing the display unit.

[0064] An embodiment of the present invention also provides a display device, as Figure 8 shown Figure 8 is a schematic structural diagram of a display device provided by an embodiment of the present invention. The display device includes a substrate 10 and a plurality of display units as provided in any embodiment of the present invention. The display device is formed by transferring a large number of display units 20 to the substrate 10. The substrate 10 includes a plurality of pixel driving circuits for driving the corresponding light-emitting units. The display units 20 are arranged in an array on the substrate 10. The display device can be a mobile phone, a tablet computer, an MP3, an MP4, a smart watch, a smart helmet, a video phone, or a personal digital assistant, etc. The preparation method of the display unit in this embodiment is relatively simple, and the workload and difficulty of the large-scale transfer are relatively low. Therefore, the manufacturing difficulty and workload of the display device are also relatively low. In addition, the display unit is a Micro-LED, which has the characteristics of small size, high integration, and self-luminescence. Compared with LCD (Liquid Crystal Display) and OLED (Organic Light Emitting Diode) in terms of display, it has greater advantages in terms of brightness, resolution, contrast, energy consumption, service life, response speed, and thermal stability.

[0065] It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. No limitation is imposed herein.

[0066] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A display unit, characterized in that, The display unit includes at least two stacked light-emitting units that emit light with different wavelengths; The display unit further includes a periodic structure disposed between two adjacent light-emitting units; the periodic structure includes a first adhesive layer and a second adhesive layer that are stacked and have different refractive indexes, and the periodic structure is used to bond the corresponding light-emitting units, reflect the emitted light of the light-emitting unit closer to the light-emitting surface side, and transmit the emitted light of the light-emitting unit farther from the light-emitting surface side.

2. The display unit according to claim 1, wherein One such periodic structure is provided between any two adjacent light-emitting units.

3. The display unit according to claim 2, characterized in that, The at least two light-emitting units include a first light-emitting unit and a second light-emitting unit, and the periodic structure is disposed between the first light-emitting unit and the second light-emitting unit; Alternatively, the at least two light-emitting units include a first light-emitting unit, a second light-emitting unit, and a third light-emitting unit, a first periodic structure is provided between the first light-emitting unit and the second light-emitting unit, and a second periodic structure is provided between the second light-emitting unit and the third light-emitting unit.

4. The display unit according to claim 1, characterized in that, The materials of the first adhesive layer and the second adhesive layer are different.

5. The display unit according to claim 1, characterized in that At least one of the first adhesive layer and the second adhesive layer includes an adhesive material and a doping material.

6. The display unit according to claim 5, wherein The adhesive material is an optical adhesive.

7. The display unit according to claim 1, characterized in that, The light-emitting unit includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer that are stacked, and the types of the first semiconductor layer and the second semiconductor layer are different.

8. A method for preparing a display unit, characterized in that, The display unit includes the display unit according to any one of claims 1-7; the method for manufacturing the display unit includes: Forming at least two types of light-emitting units with different light-emitting wavelengths; Forming the periodic structure to bond two light-emitting units to be bonded, wherein the periodic structure is further used to reflect the light emitted by one of the light-emitting units and transmit the light emitted by the other light-emitting unit.

9. The manufacturing method of the display unit according to claim 8, characterized in that, The forming the periodic structure to bond different light-emitting units includes: Forming the periodic structure on one of the light-emitting units to be bonded; Bonding the other light-emitting unit to the periodic structure.

10. A display device, characterized in that, The display device includes a substrate and a plurality of display units according to any one of claims 1-7; wherein, the display device is formed by transferring the display units to the substrate in a large quantity.

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