Display substrate, manufacturing method thereof, and display device

Abstract

This application discloses a display substrate, a method for preparing the same, and a display device, designed to improve light extraction efficiency and resolution while avoiding crosstalk. An embodiment of the application provides a display substrate comprising: a plurality of light-emitting devices arranged in an array; a photonic crystal layer located on the light-emitting side of the light-emitting devices; and a plurality of photoluminescent layers located on the side of the photonic crystal layer facing away from the light-emitting devices; the photonic crystal layer comprising: a microcavity group corresponding one-to-one to the light-emitting devices; the microcavity group comprising a plurality of point-defect microcavities; and an orthographic projection of the light-emitting devices on the photonic crystal layer covering the microcavity group.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a display substrate and a preparation method thereof, and a display device. Background Art

[0002] Micro-sized inorganic light-emitting diode (LED) displays are a new display technology that has developed rapidly in recent years. Their numerous advantages, including small chip size, controllable emission wavelength, high luminous efficiency, long lifespan, and environmentally friendly luminescent materials, have enabled the development of LED applications in displays. However, current limitations in device pads, device size, and the precision of die bonding technology make it difficult to achieve high pixel density (PPI) in micro-sized inorganic LED displays. Furthermore, to prevent crosstalk between sub-pixels, the spacing between adjacent light-emitting areas in micro-sized inorganic LED chips is large, resulting in low chip area utilization and impacting the resolution of display products. Summary of the Invention

[0003] Embodiments of the present application provide a display substrate and a method for manufacturing the same, as well as a display device, for improving light extraction efficiency and resolution while avoiding crosstalk.

[0004] An embodiment of the present application provides a display substrate, comprising: a plurality of light-emitting devices arranged in an array, a photonic crystal layer located on a light-emitting side of the light-emitting devices, and a plurality of photoluminescent layers located on a side of the photonic crystal layer facing away from the light-emitting devices;

[0005] The photonic crystal layer comprises: a microcavity group corresponding to the light emitting devices one by one; the microcavity group comprises a plurality of point defect microcavities; and the orthographic projection of the light emitting devices on the photonic crystal layer covers the microcavity group.

[0006] In some embodiments, each microcavity group includes: a first point defect microcavity, and a plurality of second point defect microcavities surrounding the first point defect microcavity;

[0007] The first point defect microcavity coincides with the center of the light-emitting device;

[0008] The distances between the plurality of second point defect microcavities and the first point defect microcavity are all equal.

[0009] In some embodiments, each microcavity group includes: four second point defect microcavities;

[0010] The four second point defect microcavities are sequentially connected to form a rectangle, and the four second point defect microcavities are respectively located at the vertices of the rectangle, and the center of the rectangle coincides with the first point defect microcavity.

[0011] In some embodiments, the photonic crystal layer further includes: a first semiconductor layer, and a plurality of first holes arranged in an array and extending through the thickness of the first semiconductor layer;

[0012] The point defect microcavity is a second hole that penetrates the thickness of the first semiconductor layer;

[0013] In a direction parallel to the plane where the photonic crystal layer is located, the maximum width of the first hole is greater than the maximum width of the second hole.

[0014] In some embodiments, in a direction parallel to the plane where the photonic crystal layer is located, a ratio of the maximum width of the second hole to the maximum width of the first hole is greater than or equal to 0.4 and less than or equal to 0.6.

[0015] In some embodiments, in the first direction, the distance h1 between the second point defect microcavity and the first point defect microcavity and the period n of the first hole satisfy the following conditions: h1 = 2n;

[0016] In the second direction, the distance h2 between the second point defect microcavity and the first point defect microcavity and the period n of the first hole satisfy the following condition: h2 = n;

[0017] The first direction is parallel to one pair of sides of the rectangle, and the second direction is parallel to the other pair of sides of the rectangle.

[0018] In some embodiments, the display substrate further includes a substrate positioned between the photonic crystal layer and the photoluminescent layer;

[0019] The substrate is lattice matched to the photonic crystal layer.

[0020] In some embodiments, the display substrate further comprises: a light shielding layer located on a side of the substrate facing away from the photonic crystal layer;

[0021] The light shielding layer has a first opening area corresponding to the light emitting devices one by one; the photoluminescent layer is located in the first opening area.

[0022] In some embodiments, the light emitting device includes: an N-type doped semiconductor layer, a multiple quantum well semiconductor layer, and a P-type doped semiconductor layer stacked in sequence on a side of the photonic crystal layer facing away from the substrate;

[0023] The photonic crystal layer, the N-type doped semiconductor layer, the multiple quantum well semiconductor layer and the P-type doped semiconductor layer include the same semiconductor material.

[0024] In some embodiments, the substrate is a sapphire substrate;

[0025] The photonic crystal layer, the N-type doped semiconductor layer, the multiple quantum well semiconductor layer and the P-type doped semiconductor layer include gallium nitride.

[0026] In some embodiments, the plurality of light emitting devices arranged in an array emit blue light;

[0027] The multiple photoluminescent layers include a red photoluminescent layer that absorbs blue light and emits red light, and a green photoluminescent layer that absorbs blue light and emits green light.

[0028] In some embodiments, the N-type doped semiconductor layers included in the plurality of light-emitting devices are integrally connected.

[0029] In some embodiments, the display substrate further includes: a red color resist located on a side of the red photoluminescent layer facing away from the substrate, a green color resist located on a side of the green photoluminescent layer facing away from the substrate, and a blue color resist located on a side of the light shielding layer facing away from the substrate in the first opening area where the photoluminescent layer is not provided.

[0030] An embodiment of the present application provides a method for preparing a display substrate, comprising:

[0031] A plurality of light-emitting devices are formed in an array arrangement, and a photonic crystal layer is formed on the light-emitting side of the light-emitting devices; wherein the photonic crystal layer includes a microcavity group corresponding one to one with the light-emitting devices, the orthographic projection of the light-emitting devices on the photonic crystal layer covers the microcavity group, and the microcavity group includes a plurality of point defect microcavities;

[0032] A plurality of photoluminescent layers are formed on a side of the photonic crystal layer away from the light emitting device.

[0033] In some embodiments, forming a plurality of light-emitting devices arranged in an array and forming a photonic crystal layer on the light-emitting side of the light-emitting devices specifically includes:

[0034] Depositing a first semiconductor layer on one side of the substrate, patterning the first semiconductor layer to form a plurality of first holes extending through the thickness of the first semiconductor layer and arranged in an array, and patterning the first semiconductor layer to form a plurality of second holes extending through the thickness of the first semiconductor layer;

[0035] An N-type doped layer, a multiple quantum well semiconductor layer, and a P-type doped semiconductor layer are sequentially grown on the side of the first semiconductor layer away from the substrate, and the multiple quantum well semiconductor layer and the P-type doped semiconductor layer are patterned.

[0036] In some embodiments, before forming a plurality of photoluminescent layers on a side of the photonic crystal layer facing away from the light-emitting device, the method further comprises:

[0037] forming a light shielding layer on a side of the substrate facing away from the photonic crystal layer, and forming a plurality of first opening areas by a patterning process;

[0038] A plurality of photoluminescent layers are formed on a side of the photonic crystal layer away from the light-emitting device, specifically comprising:

[0039] forming a photoluminescent layer in the first opening region;

[0040] After forming the photoluminescent layer on the side of the substrate facing away from the photonic crystal layer, the method further comprises:

[0041] A color resist is formed on the side of the photoluminescent layer facing away from the substrate.

[0042] A display device provided in an embodiment of the present application includes the display substrate provided in an embodiment of the present application.

[0043] In the display substrate, preparation method thereof, and display device provided in the embodiments of the present application, after the light emitted by the light-emitting device passes through the photonic crystal layer having a point defect microcavity, the divergence angle of the light is reduced due to the beam collimation effect, thereby reducing the crosstalk distance between the display substrate and the light-emitting area corresponding to the light-emitting device. That is, the aperture ratio, light extraction efficiency, and resolution of the display substrate can be improved while avoiding crosstalk between the light-emitting areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0045] Figure 1 A schematic structural diagram of a display substrate provided in an embodiment of the present application;

[0046] Figure 2 A schematic structural diagram of another display substrate provided in an embodiment of the present application;

[0047] Figure 3 A schematic structural diagram of another display substrate provided in an embodiment of the present application;

[0048] Figure 4 A schematic diagram of the light divergence angle and light extraction rate provided in an embodiment of the present application;

[0049] Figure 5 A schematic structural diagram of another display substrate provided in an embodiment of the present application;

[0050] Figure 6 A schematic flow chart of a method for preparing a display substrate provided in an embodiment of the present application. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. And in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. Based on the described embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0052] Unless otherwise defined, the technical or scientific terms used in this application should have the usual meaning understood by people with ordinary skills in the field to which this application belongs. The words "first", "second" and similar terms used in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0053] It should be noted that the sizes and shapes of the figures in the accompanying drawings do not reflect the actual scale and are only for the purpose of illustrating the contents of this application. The same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions.

[0054] The embodiment of the present application provides a display substrate, such as Figure 1 As shown, the display substrate includes: a plurality of light-emitting devices 1 arranged in an array, a photonic crystal layer 2 located on the light-emitting side of the light-emitting device 1, and a plurality of photoluminescent layers 3 located on the side of the photonic crystal layer 2 away from the light-emitting device 1;

[0055] The photonic crystal layer 2 includes: a microcavity group 4 corresponding to each light emitting device 1 ; the microcavity group 4 includes a plurality of point defect microcavities 5 ; and the orthographic projection of the light emitting device 1 on the photonic crystal layer 2 covers the microcavity group 4 .

[0056] It should be noted that the display substrate provided in the embodiment of the present application includes a photonic crystal layer. By selecting appropriate photonic crystal parameters, such as period, duty cycle, thickness, etc., the center wavelength of the photonic band gap can be set at the wavelength of the light emitted by the light-emitting device. Due to the effect of the photonic band gap, the light emitted from the light-emitting device cannot propagate in the direction parallel to the plane where the display substrate is located, and the photonic crystal cannot restrict the propagation of light in the direction perpendicular to the plane where the display substrate is located, thereby improving the vertical extraction rate of light. At the same time, the photonic crystal structure is also a grating structure. The period of the grating is set to be equivalent to the wavelength of light. When the conductive light and the grating structure interact, the component in the plane of the light wave vector will be modulated, so that the conductive light falls within the output light cone and is coupled as output light. In addition, when a point defect microcavity is introduced into the photonic crystal structure, a higher state density will appear in the photonic crystal band gap. Photons that coincide with the resonant frequency of the point defect microcavity will be localized in the narrow microcavity space, and most of the energy of the spontaneous radiation will be coupled into the defect mode, while other modes in the photonic band gap will be suppressed. The coherent coupling between the light emitted from multiple point defect microcavities produces a beam collimation effect, which not only increases light extraction efficiency but also improves the spatial directivity of the emitted light. Specifically, the maximum divergence angle of the emitted light is narrowed from ±60° without a photonic crystal layer to approximately ±30°, significantly reducing the divergence angle of the light emitted through the photonic crystal layer.

[0057] In the display substrate provided in the embodiment of the present application, after the light emitted by the light-emitting device passes through the photonic crystal layer with the point defect microcavity, the divergence angle of the light is reduced due to the beam collimation effect, thereby reducing the crosstalk distance between the display substrate and the light-emitting area corresponding to the light-emitting device, that is, the aperture ratio, light extraction efficiency and resolution of the display substrate can be improved while avoiding crosstalk between the light-emitting areas.

[0058] In some embodiments, as Figure 2 As shown, each microcavity group 4 includes: a first point defect microcavity 6, and a plurality of second point defect microcavities 7 surrounding the first point defect microcavity;

[0059] The first point defect microcavity 6 coincides with the center of the light-emitting device 1;

[0060] The distances between the plurality of second point defect microcavities 7 and the first point defect microcavity 6 are all equal.

[0061] It should be noted that Figure 2 The dotted area corresponding to the reference numeral 1 is the orthographic projection area of ​​the light-emitting device on the photonic crystal layer, that is, corresponds to the light-emitting area of ​​the light-emitting device.

[0062] In the display substrate provided in the embodiment of the present application, the first point defect microcavity in the microcavity group coincides with the center of the light-emitting area of ​​the light-emitting device, so that the light emitted through the beam collimation effect of the photonic crystal layer has the highest brightness at the center of the light-emitting area of ​​the light-emitting device, and the highest brightness of the light emitted from the photonic crystal layer is at a positive viewing angle, avoiding viewing angle deviation.

[0063] In some embodiments, as Figure 2 As shown, each microcavity group 4 includes: four second point defect microcavities 7;

[0064] The four second point defect microcavities 7 are sequentially connected to form a rectangle 19 , and the four second point defect microcavities 7 are respectively located at the vertices of the rectangle 19 , and the center of the rectangle 19 coincides with the first point defect microcavity 6 .

[0065] In some embodiments, as Figure 1 、 Figure 2 As shown, the photonic crystal layer 2 further includes: a first semiconductor layer 9 , and a plurality of first holes 8 arranged in an array and penetrating the thickness of the first semiconductor layer 9 .

[0066] That is, in the display panel provided in the embodiments of the present application, the photonic crystal layer comprises a two-dimensional photonic crystal. It should be noted that a two-dimensional photonic crystal is a photonic crystal having a periodic structure in two different directions. The period of the periodic structure in the different directions is the same. In a specific implementation, the period of the two-dimensional photonic crystal needs to be set according to the desired lattice constant of the photonic crystal, with the period of the photonic crystal being equal to its lattice constant.

[0067] In a specific implementation, the two-dimensional photonic crystal array can be a hexagonal lattice or a tetragonal lattice.

[0068] In some embodiments, as Figure 1 、 Figure 2 As shown, the point defect microcavity 5 is a second hole 10 that penetrates the thickness of the first semiconductor layer 9;

[0069] In a direction parallel to the plane where the photonic crystal layer 2 is located, the maximum width of the first hole 8 is greater than the maximum width of the second hole 10 .

[0070] That is, the second hole is a point defect microcavity of the photonic crystal relative to the first hole.

[0071] In some embodiments, in a direction parallel to the plane where the photonic crystal layer is located, a ratio of the maximum width of the second hole to the maximum width of the first hole is greater than or equal to 0.4 and less than or equal to 0.6.

[0072] In some embodiments, as Figure 2 As shown, the orthographic projections of the first hole and the second hole on the substrate are circular, and the ratio of the diameter of the second hole to the diameter of the first hole is greater than or equal to 0.4 and less than or equal to 0.6.

[0073] Taking a hexagonal lattice photonic crystal as an example, the lattice constant of the two-dimensional photonic crystal is set to 600 nanometers (nm), that is, the period of the first hole array is 600nm, the diameter of the first hole is 300nm, and the diameter of the second hole is greater than or equal to 120nm and less than or equal to 180nm.

[0074] In some embodiments, as Figure 1 、 Figure 2 As shown, the diameters of the plurality of first holes are equal, and the diameters of the plurality of second holes are equal.

[0075] In some embodiments, as Figure 2 As shown, in the first direction X, the distance h1 between the second point defect microcavity 7 and the first point defect microcavity 6 and the period n of the first hole satisfy the following conditions: h1 = 2n;

[0076] In the second direction Y, the distance h2 between the second point defect microcavity 7 and the first point defect microcavity 6 and the period n of the first hole satisfy the following condition: h2 = n;

[0077] The first direction X is parallel to one pair of sides of the rectangle 19 , and the second direction Y is parallel to the other pair of sides of the rectangle 19 .

[0078] In some embodiments, the light emitting device is a micro-sized inorganic light emitting diode, which may be, for example, a mini light emitting diode (Mini Light Emitting Diode, Mini-LED) or a micro light emitting diode (Micro Light Emitting Diode, Micro-LED).

[0079] It should be noted that Mini-LED and Micro-LED are small in size and high in brightness, making them suitable for widespread use in display devices or their backlight modules. For example, the typical size (e.g., length) of a Micro-LED is less than 100 microns; the typical size (e.g., length) of a Mini-LED is 80 to 350 microns.

[0080] In some embodiments, as Figure 1 As shown, the display substrate further includes a substrate 14 located between the photonic crystal layer 2 and the photoluminescent layer 3;

[0081] The substrate 14 is lattice-matched to the photonic crystal layer 2 .

[0082] In some embodiments, as Figure 1 As shown, the light emitting device 1 includes: an N-type doped semiconductor layer 11 , a multiple quantum well semiconductor layer 12 , and a P-type doped semiconductor layer 13 , which are sequentially stacked on a side of a photonic crystal layer 2 facing away from a substrate 15 .

[0083] In a specific implementation, the N-type doped semiconductor layer serves as the cathode of the light-emitting device, the P-type doped semiconductor layer serves as the anode of the light-emitting device, and the multiple quantum well semiconductor layer serves as the light-emitting layer of the light-emitting device.

[0084] In some embodiments, the photonic crystal layer, the N-type doped semiconductor layer, the multiple quantum well semiconductor layer, and the P-type doped semiconductor layer include the same semiconductor material.

[0085] The material of the photonic crystal layer is lattice-matched with the substrate, and the first semiconductor layer, the N-type doped semiconductor layer, the multiple quantum well semiconductor layer and the P-type doped semiconductor layer include the same material, that is, the lattice matching between the materials of the substrate, the photonic crystal and the light-emitting device can avoid the growth of various film layers of the light-emitting device under the condition of lattice mismatch, which affects the light efficiency of the light-emitting device.

[0086] In some embodiments, the substrate is a sapphire substrate;

[0087] The first semiconductor layer, the N-type doped semiconductor layer, the multiple quantum well semiconductor layer and the P-type doped semiconductor layer included in the photonic crystal layer include gallium nitride.

[0088] In some embodiments, the plurality of light emitting devices arranged in an array emit blue light;

[0089] like Figure 1 As shown, the multiple photoluminescent layers 3 include: a red photoluminescent layer r that absorbs blue light and emits red light, and a green photoluminescent layer g that absorbs blue light and emits green light.

[0090] In some embodiments, the photoluminescent layer includes quantum dots.

[0091] In some embodiments, as Figure 1 As shown, the display substrate further includes: a light shielding layer 15 located on a side of the substrate 14 away from the photonic crystal layer 2;

[0092] The light shielding layer 15 has first opening regions 18 corresponding to the light emitting devices 1 ; the photoluminescent layer 3 is located in the first opening regions 18 .

[0093] In specific implementation, Figure 1 As shown, the first opening region 18 exposes the light emitting region of the light emitting device 1. In some embodiments, the orthographic projection of the first opening region on the substrate may coincide with the orthographic projection of the light emitting region of the light emitting device on the substrate.

[0094] When a plurality of light emitting devices arranged in an array emit blue light, in some embodiments, such as Figure 1As shown, the light shielding layer 15 includes a plurality of first opening regions 18, including a red sub-pixel opening region R', a blue sub-pixel opening region B', and a green sub-pixel opening region G'. A red photoluminescent layer r is located in the red sub-pixel opening region R', a green photoluminescent layer g is located in the green sub-pixel opening region G', and no photoluminescent layer is provided in the blue sub-pixel opening region B'.

[0095] It should be noted that the display substrate includes a plurality of pixels, and each pixel includes a plurality of sub-pixels. The sub-pixels include at least one light-emitting device. In some embodiments, each sub-pixel includes a light-emitting device. In a specific implementation, a pixel includes, for example, a red sub-pixel, a blue sub-pixel, and a green sub-pixel. For a micro-sized inorganic light-emitting diode display substrate, since the light-emitting devices all emit blue light, in a specific implementation, Figure 3 As shown, a blue light micro-size inorganic light emitting diode chip can be divided into sub-pixels. The area R corresponding to the red sub-pixel uses a red light photoluminescent layer that absorbs blue light and emits red light to emit red light. The area G corresponding to the green sub-pixel uses a green light photoluminescent layer that absorbs blue light and emits green light to emit green light. The light-emitting device in the blue sub-pixel area B emits blue light, so there is no need to set up a photoluminescent layer. That is, one pixel can correspond to one micro-size inorganic light emitting diode chip, so that the blue light micro-size inorganic light emitting diode chips can be bound to achieve full-color display.

[0096] It should be noted that the divergence angle of the light and the light extraction efficiency of the light emitting device are as follows: Figure 4 As shown, Figure 4 The dashed line represents the divergence angle of light that has not passed through the photonic crystal layer and the light extraction efficiency of the light emitting device, and the solid line represents the divergence angle of light that has passed through the photonic crystal layer and the light extraction efficiency of the light emitting device. Figure 4 It can be seen that under the coherent coupling of multiple point defect microcavities in the photonic crystal layer, the maximum angle of the light divergence angle can be reduced from plus or minus 60° to plus or minus 35° due to the beam collimation effect, and the light extraction rate of the light-emitting device is greatly improved. Accordingly, the crosstalk distance between the sub-pixels corresponding to the light-emitting device of the present application can be reduced to about one-third of the original crosstalk distance, that is, the distance between the sub-pixels can be greatly reduced to reduce the overall size of the blue light micro-size inorganic light-emitting diode chip. Accordingly, for a blue light micro-size inorganic light-emitting diode chip, compared with the case where the photonic crystal layer is not set, the utilization rate of the blue light micro-size inorganic light-emitting diode chip can be increased by about 2 times. The original crosstalk distance refers to the crosstalk distance between the light-emitting areas corresponding to the light-emitting device when the photonic crystal layer of the present application is not set.

[0097] In some embodiments, as Figure 1 As shown, the N-type doped semiconductor layers 11 included in the plurality of light emitting devices 1 are integrally connected.

[0098] In some embodiments, as Figure 5 As shown, the display substrate further includes: a color resist 20 located on the side of the photoluminescent layer and the light shielding layer facing away from the substrate.

[0099] In some embodiments, as Figure 5 As shown, the color resist 20 includes: a red color resist r' located on the side of the red photoluminescent layer r facing away from the substrate 14, a green color resist g' located on the side of the green photoluminescent layer g facing away from the substrate 14, and a blue color resist b' located on the side of the light shielding layer 15 facing away from the substrate 14 in the first opening area 18 where the photoluminescent layer 3 is not provided.

[0100] In some embodiments, as Figure 5 As shown, the display substrate also includes: a buffer layer 22 located between the photonic crystal layer 2 and the light-emitting device 1, an encapsulation layer 21 located on the side of the color resist 20 facing away from the substrate 14, and a flat layer 16 located on the side of the light-emitting device 1 facing away from the substrate 14, and a bonding pad 17 located on the side of the flat layer 16 facing away from the substrate and electrically connected to the light-emitting device 1 through a via hole penetrating the flat layer 16.

[0101] In a specific implementation, the buffer layer and the first semiconductor layer include the same material, for example, the buffer layer includes gallium nitride.

[0102] In some embodiments, the thickness of the first semiconductor layer is 300 nm, the thickness of the substrate is 60 microns, the thickness of the buffer layer and the thickness of the N-type doped semiconductor layer are both 2 microns, the thickness of the multiple quantum well semiconductor layer and the thickness of the P-type doped semiconductor layer are both 0.3 microns, and the thickness of the photoluminescent layer and the light-shielding layer is 10 microns.

[0103] In specific implementation, Figure 5 As shown, the bonding pads include: a first bonding pad 23 electrically connected to the P-type doped semiconductor layer 13, and a second bonding pad (not shown) electrically connected to the N-type doped semiconductor layer. In a specific implementation, the second bonding pad can be set, for example, at Figure 3 Middle D area.

[0104] In some embodiments, the display substrate further includes a driver backplane located on a side of the substrate facing away from the bonding pads. Specifically, the micro-sized inorganic light-emitting diode chip is bonded to the driver backplane. The driver backplane is used to provide signals to the light-emitting device. The driver backplane, for example, includes a transistor, a signal line, and a third bonding pad, which is bonded to the first and second bonding pads.

[0105] In a specific implementation, a plurality of blue light micro-sized inorganic light emitting diodes can be bound to a driving backplane to obtain a display substrate.

[0106] It should be noted that Figures 1 to 5The distance is described using a micro-sized inorganic light-emitting diode as an example. Of course, in some embodiments, the light-emitting device may also be an organic light-emitting diode. In a specific implementation, when the light-emitting device is an organic light-emitting diode, the display substrate further includes: a base substrate located on the side of the light-emitting device facing away from the photonic crystal layer, and a drive circuit layer located between the base substrate and the light-emitting device. The drive circuit layer, for example, includes pixel drive circuits arranged in an array and electrically connected to the light-emitting devices. The pixel drive circuits, for example, include transistors and capacitors.

[0107] Based on the same inventive concept, the present application also provides a method for preparing a display substrate, such as Figure 6 As shown, including:

[0108] S101, forming a plurality of light-emitting devices arranged in an array and forming a photonic crystal layer on the light-emitting side of the light-emitting devices; wherein the photonic crystal layer includes a microcavity group corresponding to each light-emitting device, the orthographic projection of the microcavity group on the substrate falls within the orthographic projection of the micro-sized inorganic light-emitting diode device, and the microcavity group includes a plurality of point defect microcavities;

[0109] S102 , forming a plurality of photoluminescent layers on a side of the photonic crystal layer away from the light-emitting device.

[0110] Next, the preparation method of the lower substrate provided in the embodiment of the present application is introduced by taking the light-emitting device as a micro inorganic light-emitting diode as an example.

[0111] In some embodiments, step S101 of forming a plurality of light-emitting devices arranged in an array and forming a photonic crystal layer on the light-emitting side of the light-emitting devices specifically includes:

[0112] Depositing a first semiconductor layer on one side of the substrate, patterning the first semiconductor layer to form a plurality of first holes extending through the thickness of the first semiconductor layer and arranged in an array, and patterning the first semiconductor layer to form a plurality of second holes extending through the thickness of the first semiconductor layer;

[0113] An N-type doped layer, a multiple quantum well semiconductor layer, and a P-type doped semiconductor layer are sequentially grown on the side of the first semiconductor layer away from the substrate, and the multiple quantum well semiconductor layer and the P-type doped semiconductor layer are patterned.

[0114] The display substrate fabrication method provided in the embodiments of the present application forms a first hole through the thickness of a first semiconductor layer to form a two-dimensional photonic crystal, and forms a second hole through the thickness of the first semiconductor layer to form a point defect microcavity. Both the two-dimensional photonic crystal and the point defect microcavity can be formed through a simple patterning process. After formation, the two-dimensional photonic crystal and the point defect microcavity are not easily deformed and have high stability, thus avoiding affecting the alignment performance of the photonic crystal layer. Furthermore, by first forming a photonic crystal layer on the substrate, and then growing the various light-emitting device film layers on one side of the photonic crystal layer, the photonic crystal layer is positioned within the light-emitting device chip. This eliminates the need for additional processes to fabricate the photonic crystal layer and bond it to the light-emitting device chip, simplifying the display substrate fabrication process and saving costs.

[0115] In some embodiments, a first semiconductor layer is deposited on one side of a substrate, a patterning process is performed on the first semiconductor layer to form a plurality of first holes extending through the thickness of the first semiconductor layer and arranged in an array, and a patterning process is performed on the first semiconductor layer to form a plurality of second holes extending through the thickness of the first semiconductor layer, specifically comprising:

[0116] A gallium nitride layer is deposited on one side of a sapphire substrate, and the gallium nitride layer is patterned to form a plurality of first holes penetrating the thickness of the gallium nitride layer and arranged in an array, and the gallium nitride layer is patterned to form a plurality of second holes penetrating the thickness of the gallium nitride layer.

[0117] During specific implementation, the patterning process may include, for example, steps such as coating, exposure, development, and etching.

[0118] In some embodiments, an N-type doped layer, a multiple quantum well semiconductor layer, and a P-type doped semiconductor layer are sequentially grown on a side of the first semiconductor layer facing away from the substrate, and a patterning process is performed on the multiple quantum well semiconductor layer and the P-type doped semiconductor layer, specifically including:

[0119] Growing a gallium nitride layer as a buffer layer on the side of the gallium nitride layer facing away from the substrate;

[0120] On the side of the buffer layer facing away from the sapphire substrate, an N-type doped GaN layer, a multi-quantum well GaN layer, and a P-type doped GaN layer are sequentially grown;

[0121] The multi-quantum well gallium nitride layer and the P-type doped gallium nitride layer are patterned.

[0122] In some embodiments, before forming a plurality of photoluminescent layers on a side of the photonic crystal layer facing away from the light-emitting device, the method further includes:

[0123] A light shielding layer is formed on a side of the substrate away from the photonic crystal layer, and a plurality of first opening areas are formed by adopting a patterning process.

[0124] In a specific implementation, for example, a printing or nano-imprinting process can be used to form a light-shielding layer on the side of the sapphire substrate away from the photonic crystal layer.

[0125] In some embodiments, a plurality of photoluminescent layers are formed on a side of the photonic crystal layer facing away from the light-emitting device, specifically comprising:

[0126] A photoluminescent layer is formed in the first opening region.

[0127] In a specific implementation, a red photoluminescent layer is formed in the red sub-pixel opening region, and a green photoluminescent layer is formed in the green sub-pixel opening region.

[0128] In some embodiments, after forming the photoluminescent layer on the side of the substrate facing away from the photonic crystal layer, the method further comprises:

[0129] A color resist is formed on the side of the photoluminescent layer facing away from the substrate.

[0130] In a specific implementation, a red color resist is formed on the side of the red photoluminescent layer facing away from the substrate, a green color resist is formed on the side of the green photoluminescent layer facing away from the substrate, and a blue color resist is formed on the side of the light shielding layer facing away from the substrate in the first opening area where no photoluminescent layer is provided.

[0131] In some embodiments, when the light-emitting device is an organic light-emitting diode, step S101 forms a plurality of light-emitting devices arranged in an array and forms a photonic crystal layer on the light-emitting side of the light-emitting device, specifically including:

[0132] A driving circuit layer and an organic light emitting diode are sequentially formed on one side of the base substrate.

[0133] A display device provided in an embodiment of the present application includes the display substrate provided in an embodiment of the present application.

[0134] In a specific implementation, the display substrate can serve as a display panel of a display device. Alternatively, the display substrate can serve as a backlight module of the display device. When the display substrate serves as a backlight module, the display device further includes a display panel located on the light-emitting side of the display substrate.

[0135] The display device provided in the embodiments of this application is any product or component with a display function, such as a mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, or navigation system. Other essential components of the display device are well understood by those skilled in the art and are not described here in detail, nor should they be construed as limitations of this application. The implementation of the display device can be referenced to the above-described embodiments of the display substrate, and any repetitive details will not be repeated.

[0136] In summary, in the display substrate, preparation method thereof, and display device provided in the embodiments of the present application, after the light emitted by the light-emitting device passes through the photonic crystal layer with a point defect microcavity, the divergence angle of the light is reduced due to the beam collimation effect, thereby reducing the crosstalk distance between the display substrate and the light-emitting area corresponding to the light-emitting device, that is, the aperture ratio, light extraction efficiency, and resolution of the display substrate can be improved while avoiding crosstalk between the light-emitting areas.

[0137] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A display substrate, characterized in that: The display substrate comprises: a plurality of light emitting devices arranged in an array, a photonic crystal layer located on the light emitting side of the light emitting device, and a plurality of photoluminescent layers located on the side of the photonic crystal layer away from the light emitting device; The photonic crystal layer comprises: a microcavity group corresponding to the light-emitting devices one by one; the microcavity group comprises a plurality of point defect microcavities; the orthographic projection of the light-emitting device on the photonic crystal layer covers the microcavity group; The light emitting device comprises: a buffer layer, an N-type doped semiconductor layer, a multiple quantum well semiconductor layer, and a P-type doped semiconductor layer stacked in sequence on a side of the photonic crystal layer away from the photoluminescent layer; The photonic crystal layer, the buffer layer, the N-type doped semiconductor layer, the multiple quantum well semiconductor layer, and the P-type doped semiconductor layer include gallium nitride; The photonic crystal layer further includes a connecting portion between the microcavity groups corresponding to the light-emitting devices one by one, and the connecting portion also includes a plurality of point defect microcavities; The plurality of light emitting devices arranged in an array emit blue light; The plurality of photoluminescent layers include: a red photoluminescent layer that absorbs blue light and emits red light, and a green photoluminescent layer that absorbs blue light and emits green light; The display substrate includes a plurality of pixels, each of which includes a red sub-pixel, a blue sub-pixel, and a green sub-pixel; the area corresponding to the red sub-pixel utilizes a red light photoluminescent layer that absorbs blue light and emits red light to emit red light, the area corresponding to the green sub-pixel utilizes a green light photoluminescent layer that absorbs blue light and emits green light to emit green light, and the area corresponding to the blue sub-pixel emits blue light.

2. The display substrate according to claim 1, wherein: Each of the microcavity groups includes: a first point defect microcavity, and a plurality of second point defect microcavities surrounding the first point defect microcavity; The first point defect microcavity coincides with the center of the light-emitting device; The distances between the plurality of second point defect microcavities and the first point defect microcavity are all equal.

3. The display substrate according to claim 2, wherein: Each of the microcavity groups includes: four of the second point defect microcavities; The four second point defect microcavities are sequentially connected to form a rectangle, and the four second point defect microcavities are respectively located at vertices of the rectangle, and the center of the rectangle coincides with the first point defect microcavity.

4. The display substrate according to claim 3, wherein: The photonic crystal layer further includes: a first semiconductor layer, and a plurality of first holes arranged in an array and penetrating the thickness of the first semiconductor layer; The point defect microcavity is a second hole that penetrates the thickness of the first semiconductor layer; In a direction parallel to the plane where the photonic crystal layer is located, the maximum width of the first hole is greater than the maximum width of the second hole.

5. The display substrate according to claim 4, wherein: In a direction parallel to the plane where the photonic crystal layer is located, a ratio of a maximum width of the second hole to a maximum width of the first hole is greater than or equal to 0.4 and less than or equal to 0.

6.

6. The display substrate according to claim 4, wherein: In the first direction, the distance h1 between the second point defect microcavity and the first point defect microcavity and the period n of the first hole satisfy the following condition: h1=2n; In the second direction, the distance h2 between the second point defect microcavity and the first point defect microcavity and the period n of the first hole satisfy the following condition: h2=n; The first direction is parallel to one pair of sides of the rectangle, and the second direction is parallel to the other pair of sides of the rectangle.

7. The display substrate according to any one of claims 1 to 6, wherein: The display substrate further includes a substrate located between the photonic crystal layer and the photoluminescent layer; The substrate is lattice-matched to the photonic crystal layer.

8. The display substrate according to claim 7, wherein: The display substrate further comprises: a light shielding layer located on a side of the substrate away from the photonic crystal layer; The light shielding layer has a first opening area corresponding to the light emitting devices one by one; the photoluminescent layer is located in the first opening area.

9. The display substrate according to claim 7, wherein: The substrate is a sapphire substrate.

10. The display substrate according to claim 1, wherein The N-type doped semiconductor layers included in the plurality of light-emitting devices are integrally connected.

11. The display substrate according to claim 8, wherein The display substrate further includes: a red color resist located on a side of the red photoluminescent layer facing away from the substrate, a green color resist located on a side of the green photoluminescent layer facing away from the substrate, and a blue color resist located on a side of the light shielding layer facing away from the substrate in the first opening area where the photoluminescent layer is not provided.

12. A method for preparing a display substrate, characterized in that: The method comprises: A plurality of light-emitting devices are formed in an array and a photonic crystal layer is formed on the light-emitting side of the light-emitting devices; wherein the photonic crystal layer includes a microcavity group corresponding to each of the light-emitting devices, the orthographic projection of the light-emitting device on the photonic crystal layer covers the microcavity group, and the microcavity group includes a plurality of point defect microcavities; A plurality of photoluminescent layers are formed on a side of the photonic crystal layer away from the light-emitting device; wherein the light-emitting device comprises: a buffer layer, an N-type doped semiconductor layer, a multiple quantum well semiconductor layer, and a P-type doped semiconductor layer stacked in sequence on a side of the photonic crystal layer away from the photoluminescent layer; The photonic crystal layer, the buffer layer, the N-type doped semiconductor layer, the multiple quantum well semiconductor layer, and the P-type doped semiconductor layer include gallium nitride; The photonic crystal layer further includes a connecting portion between the microcavity groups corresponding to the light-emitting devices one by one, and the connecting portion also includes a plurality of point defect microcavities; The plurality of light emitting devices arranged in an array emit blue light; The plurality of photoluminescent layers include: a red photoluminescent layer that absorbs blue light and emits red light, and a green photoluminescent layer that absorbs blue light and emits green light; The display substrate includes a plurality of pixels, each of which includes a red sub-pixel, a blue sub-pixel, and a green sub-pixel; the area corresponding to the red sub-pixel utilizes a red light photoluminescent layer that absorbs blue light and emits red light to emit red light, the area corresponding to the green sub-pixel utilizes a green light photoluminescent layer that absorbs blue light and emits green light to emit green light, and the area corresponding to the blue sub-pixel emits blue light.

13. The method according to claim 12, characterized in that Forming a plurality of light-emitting devices arranged in an array and forming a photonic crystal layer on the light-emitting side of the light-emitting devices specifically includes: Depositing a first semiconductor layer on one side of a substrate, patterning the first semiconductor layer to form a plurality of first holes extending through the thickness of the first semiconductor layer and arranged in an array, and patterning the first semiconductor layer to form a plurality of second holes extending through the thickness of the first semiconductor layer; An N-type doped layer, a multiple quantum well semiconductor layer, and a P-type doped semiconductor layer are sequentially grown on a side of the first semiconductor layer away from the substrate, and a patterning process is performed on the multiple quantum well semiconductor layer and the P-type doped semiconductor layer.

14. The method according to claim 12, characterized in that Before forming a plurality of photoluminescent layers on a side of the photonic crystal layer facing away from the light-emitting device, the method further comprises: forming a light shielding layer on a side of the substrate away from the photonic crystal layer, and forming a plurality of first opening areas by a patterning process; A plurality of photoluminescent layers are formed on a side of the photonic crystal layer away from the light-emitting device, specifically comprising: forming the photoluminescent layer in the first opening area; After forming a photoluminescent layer on a side of the substrate facing away from the photonic crystal layer, the method further comprises: A color resist is formed on a side of the photoluminescent layer facing away from the substrate.

15. A display device, characterized in that: The display substrate comprises the display substrate according to any one of claims 1 to 11.

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