Display substrate, manufacturing method therefor, and display apparatus

Abstract

A display substrate. The display substrate has a light-emitting side and a non-light-emitting side. The display substrate further comprises a first substrate and a plurality of light-emitting devices arranged thereon. Each of the plurality of light-emitting devices comprises, stacked in the direction away from the first substrate, a first electrode, a first functional layer, a quantum dot light-emitting layer, a second functional layer, and a second electrode. The plurality of light-emitting devices comprise at least two types of light-emitting devices, each type of light-emitting devices being configured to emit light of one color, and thicknesses of the first electrodes included in the at least two types of light-emitting devices not being equal to each other.

Description

Display substrate, preparation method thereof and display device

[0001] This application claims priority to the Chinese patent application No. 202410831758.3, filed on June 25, 2024, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

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

[0003] Quantum dots (QDs) are nanoparticles with a radius less than or close to the Bohr exciton radius, which have the advantages of narrow emission spectrum, adjustable emission wavelength, high spectral purity, high luminous efficiency, etc. and have great application prospects in the fields of display and lighting, and are expected to become the core part of the next generation of light-emitting devices. Among them, Quantum Dot Light-emitting Diode (QLED) is an important way for quantum dot light-emitting devices to be applied in the field of display. SUMMARY

[0004] In one aspect, a display substrate is provided. The display substrate has a light-out side and a non-light-out side. The display substrate further includes a first substrate and a plurality of light-emitting devices disposed on the first substrate. Each of the plurality of light-emitting devices includes a first electrode, a first functional layer, a quantum dot light-emitting layer, a second functional layer, and a second electrode stacked in a direction away from the first substrate. The plurality of light-emitting devices includes at least two types of light-emitting devices, one type of light-emitting device is configured to emit light of one color, and the thicknesses of the first electrodes of the at least two types of light-emitting devices are not equal.

[0005] In some embodiments, the first electrode is farther away from the light-out side than the second electrode. The plurality of light-emitting devices includes red light-emitting devices, green light-emitting devices, and blue light-emitting devices. The thickness of the first electrode of the red light-emitting devices is less than the thickness of the first electrode of the blue light-emitting devices. The thickness of the first electrode of the blue light-emitting devices is less than the thickness of the first electrode of the green light-emitting devices.

[0006] In some embodiments, the thickness of the first electrode of the red light-emitting devices is 10-20 nm; and / or, the thickness of the first electrode of the blue light-emitting devices is 65-75 nm; and / or, the thickness of the first electrode of the green light-emitting devices is 120-130 nm.

[0007] In some embodiments, the light emitting device further comprises a reflective layer on the first electrode close to the first substrate; the thickness of the reflective layer belonging to the red light emitting device, the green light emitting device and the blue light emitting device respectively is equal.

[0008] In some embodiments, the first electrode is closer to the light emitting side than the second electrode. The plurality of light emitting devices comprises a red light emitting device, a green light emitting device and a blue light emitting device; the thickness of the first electrode of the red light emitting device is greater than the thickness of the first electrode of the green light emitting device; the thickness of the first electrode of the green light emitting device is greater than the thickness of the first electrode of the blue light emitting device.

[0009] In some embodiments, the thickness of the first electrode of the red light emitting device is 130nm-150nm; and / or, the thickness of the first electrode of the blue light emitting device is 60nm-70nm; and / or, the thickness of the first electrode of the green light emitting device is 90nm-110nm.

[0010] In some embodiments, the thickness of the first functional layer, the second functional layer and the second electrode belonging to the red light emitting device, the green light emitting device and the blue light emitting device respectively is equal.

[0011] In some embodiments, the material of the first electrode comprises a transparent conductive material.

[0012] In another aspect, a display device is provided, comprising a driving circuit board and the display substrate in any of the above embodiments. The driving circuit board is electrically connected with the display substrate and is configured to transmit a control signal to the display substrate.

[0013] In yet another aspect, a preparation method of a display substrate is provided. The preparation method comprises: forming a conductive layer on a first substrate, the conductive layer covering the first substrate; forming a mask layer on the conductive layer, the mask layer covering part of the conductive layer; patterning the conductive layer according to the mask layer to form a plurality of first electrodes; repeating the above steps to form at least two patterned conductive layers, the thickness of the at least two patterned conductive layers being unequal.

[0014] In some embodiments, the display substrate includes a red light emitting device, a green light emitting device, and a blue light emitting device, each of which includes a first electrode. The preparation method includes: forming a first conductive layer on a first substrate; the first conductive layer covers the first substrate. Forming a first mask layer on the first conductive layer; the first mask layer covers part of the first conductive layer. The first conductive layer is patterned according to the first mask layer to form a plurality of first sub-electrodes. Forming a second conductive layer on the first substrate; the second conductive layer covers the first mask layer and the area of the first substrate not covered by the first sub-electrode. Forming a second mask layer on the second conductive layer; the second mask layer covers part of the second conductive layer and at least exposes the area of the second conductive layer covering the first mask layer. The second conductive layer is patterned according to the second mask layer to form a plurality of second sub-electrodes. Forming a third conductive layer on the first substrate; the third conductive layer covers the first mask layer, the second mask layer, and the area of the first substrate not covered by the first mask layer and the second mask layer. Forming a third mask layer on the third conductive layer; the third mask layer covers part of the third conductive layer and at least exposes the part of the third conductive layer covering the first mask layer and the second mask layer. The third conductive layer is patterned according to the third mask layer to form a plurality of third sub-electrodes. The first mask layer, the second mask layer, and the third mask layer are removed. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the present disclosure, the following will briefly introduce the drawings needed to be used in some embodiments of the present disclosure. Obviously, the drawings described in the following description are only the drawings of some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art according to these drawings. In addition, the drawings in the following description can be regarded as schematic diagrams, and are not limited to the actual size, actual process, actual timing of signals, etc. of the products involved in the embodiments of the present disclosure.

[0016] FIG. 1 is a plan view of a display device according to some embodiments;

[0017] FIG. 2A is a structural view of a display device according to some embodiments;

[0018] FIG. 2B is another structural view of a display device according to some embodiments;

[0019] FIG. 3 is a structural view of a top emission display substrate according to some embodiments;

[0020] FIG. 4 is a structural view of a bottom emission display substrate according to some embodiments;

[0021] FIG. 5 is a graph of first electrode thickness versus luminous intensity of a light emitting device, according to some embodiments;

[0022] FIG. 6 is a graph of first electrode thickness versus light extraction efficiency of a light emitting device, according to some embodiments;

[0023] FIG. 7 is a graph of first electrode thickness versus current density of a light emitting device, according to some embodiments;

[0024] FIG. 8 is a graph of first electrode thickness versus luminous intensity of a light emitting device, according to some embodiments;

[0025] FIG. 9 is a graph of first electrode thickness versus external quantum efficiency of a light emitting device, according to some embodiments;

[0026] FIGS. 10A-10G are process diagrams of a display substrate, according to some embodiments. DETAILED DESCRIPTION

[0027] The technical solutions in some embodiments of the present disclosure will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided in the present disclosure, all other embodiments obtained by a person of ordinary skill in the art belong to the scope of protection of the present disclosure.

[0028] Unless otherwise required by context, the term “comprise” and its other forms such as “comprises” and “comprising” are to be construed as open, inclusive, meaning, i.e., “including, but not limited to.” In the description of the specification, the terms “one embodiment,” “some embodiments,” “exemplary embodiments,” “example,” “specific example” or “some examples” are intended to mean that a particular feature, structure, material, or characteristic included in at least one embodiment or example of the present disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials, or characteristics described can be included in any appropriate manner in any one or more embodiments or examples.

[0029] The terms "first", "second", etc. are used herein only to describe an order or sequence and are not used to denote or imply relative importance or a specific number of the indicated technical features. Thus, features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, the meaning of "a plurality" is two or more, unless otherwise specified.

[0030] In describing some embodiments, "coupled" and "connected", and variations thereof, can be used. The term "connected" is used broadly and encompass both direct and indirect connections, such as fixed or detachable connections, or integrally formed; and can be direct connections or indirect connections through an intermediate medium. The term "coupled" indicates, for example, that two or more components are in direct physical or electrical contact. The term "coupled" or "communicatively coupled" can also mean that two or more components do not have direct contact with each other, but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited by the content herein.

[0031] "A, B, and C at least one of" has the same meaning as "at least one of A, B, or C", both of which include the following combinations: only A, only B, only C, a combination of A and B, a combination of A and C, a combination of B and C, and a combination of A, B, and C.

[0032] "A and / or B" includes the following three combinations: only A, only B, and a combination of A and B.

[0033] The use of "adapted to" or "configured to" herein means open and inclusive language that does not exclude devices adapted to or configured to perform additional tasks or steps.

[0034] In addition, the use of "based on" means open and inclusive, as a process, step, calculation, or other action that is "based on" one or more recited conditions or values can be based on additional conditions or values beyond those recited.

[0035] As used herein, "about", "approximately", or "around" includes the recited value and the average value within an acceptable range of deviation from the particular value, as determined by a person of ordinary skill in the art taking into account the measurement being discussed and the error associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0036] As used herein, "parallel," "perpendicular," "equal" include the recited condition and conditions that are approximately the recited condition, the range of which is within an acceptable deviation range, as determined by one of ordinary skill in the art taking into account the measurement being discussed and the error associated with the measurement of the particular quantity (i.e., limitations of the measurement system). For example, "parallel" includes absolute parallel and approximately parallel, where the acceptable deviation range for approximately parallel can be, for example, within 5°; "perpendicular" includes absolute perpendicular and approximately perpendicular, where the acceptable deviation range for approximately perpendicular can also be, for example, within 5°. "Equal" includes absolute equality and approximate equality, where the acceptable deviation range for approximately equal can be, for example, a difference between the two that is less than or equal to 5% of either.

[0037] It will be understood that when a layer or element is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening layers can also be present.

[0038] Exemplary embodiments are described herein with reference to cross-sectional and / or plan view illustrations that are idealized examples of exemplary embodiments. In the interest of clarity, not all of the circular features can be shown in the drawings. It will be understood that in the drawings, the thickness of layers and regions are exaggerated for clarity, and that the dimensions of the layers and regions shown in the drawings can not be to scale. Accordingly, exemplary embodiments should not be construed as limited to the shapes of regions illustrated in the drawings, which are schematically represented. For example, the etched regions illustrated in the drawings typically have curved features that are not illustrated. Thus, the regions illustrated in the drawings are schematic and not intended to be limiting of the scope of exemplary embodiments.

[0039] Referring to FIG. 1, an embodiment of the present disclosure provides a display device 1000, which is a product having an image display function. Exemplarily, the display device 1000 can be any device that displays whether moving (e.g., a video) or fixed (e.g., a still image) and whether a character or an image.

[0040] The display device 1000 described above can be applied to various electronic devices, such as a mobile phone, a wireless device, a personal data assistant (PDA), a wearable device, an augmented reality (AR) device, a virtual reality (VR) device, a handheld or portable computer, a GPS receiver / navigator, a camera, an MP4 video player, a camcorder, a game console, a watch, a clock, a calculator, a television monitor, a flat panel display, a computer monitor, an automobile display (e.g., a speedometer display, etc.), a cockpit controller and / or display, a display of a camera view (e.g., a display of a rear view camera in a vehicle), an electronic photograph, an electronic billboard or sign, a projector, a packaging and aesthetic structure (e.g., a display of an image for a piece of jewelry), etc. For example, as shown in FIG. 1, the display device 1000 can be a mobile phone.

[0041] In some embodiments, the display device 1000 includes a display substrate 1100 and a driving circuit board (not shown in the figures), which is electrically connected to the display substrate 1100 and configured to transmit a control signal to the display substrate 1100 to drive the display substrate to emit light.

[0042] Exemplarily, the display device 1000 described above can be a liquid crystal display (LCD). In the case where the display device 1000 is a liquid crystal display, referring to FIG. 2A, the display device 1000 can include, but is not limited to, a display substrate 1100, a liquid crystal display panel 1200, and an upper polarizer 1300, which are arranged in a stack. At this time, the display substrate 1100 can be part of a backlight module constituting the display device, and the display substrate 1100 is arranged on a non-light-emitting side of the liquid crystal display panel 1200 and configured to provide a light source for the liquid crystal display panel 1200. The liquid crystal display panel 1200 includes a plurality of sub-pixels, each of which is configured to modulate linearly polarized light rays entering the sub-pixel to adjust the polarization direction of light rays emitted by the sub-pixel. The upper polarizer 1300 is arranged on a light-emitting side of the liquid crystal display panel 1200 and configured to filter linearly polarized light emitted by each sub-pixel, so that light rays with the same polarization direction as the polarizer optical axis direction of the upper polarizer are emitted, and light rays with a polarization direction perpendicular to the polarizer optical axis direction of the upper polarizer are blocked, to realize display of different gray scales and thus realize image display.

[0043] Exemplarily, the display device 1000 can also be a direct display device (such as a Micro-LED display device or a mini-LED display device). At this time, the display device 1000 can include a display substrate 1100, which can be directly used for picture display, that is, the display substrate 1100 directly displays images.

[0044] In some other embodiments, the display device 1000 can also be a 3D display device. As shown in FIG. 2B, the display device 1000 can include the display substrate 1100 and an optical module 1600 sequentially stacked on the light-emitting side of the display substrate 1100. The optical module can include, for example, a first polarizer 610, a half-transmission half-reflection film 620, a first lens 630, a second polarizer 640, a reflective polarizer 650, and a second lens 660 sequentially arranged along the light-emitting direction of the display substrate 1100. The first polarizer 610 and the second polarizer 640 can each be a 1 / 4 wave plate, and the first lens 630 and the second lens 660 can increase the optical path of the light emitted by the display substrate 1100 and can magnify the image displayed by the display substrate 1100.

[0045] The light path of the light emitted by the display device 1000 and incident into the human eye E is briefly introduced below. As shown in FIG. 2B, the light emitted by the display substrate 1100 can be linearly polarized light (for example, TM light). The polarized light is incident into the first polarizer 610, converted into circularly polarized light, and then emitted. The circularly polarized light is incident into the half-transmission half-reflection film 620, and part of the circularly polarized light is transmitted and then emitted to the second polarizer 640 through the first lens 630. The part of the circularly polarized light is converted into linearly polarized light (for example, TE light) by the second polarizer 640 and then emitted to the reflective polarizer 650. The linearly polarized light is reflected by the reflective polarizer 650 and then incident into the second polarizer 640 again, converted into circularly polarized light by the second polarizer 640, and then transmitted through the first lens 630 and incident into the half-transmission half-reflection film 620. Part of the circularly polarized light is reflected by the half-transmission half-reflection film 620 to the second polarizer 640, converted into linearly polarized light (for example, TM light) by the second polarizer 640, and then incident into the reflective polarizer 650. The linearly polarized light is transmitted through the reflective polarizer 650 and the second lens 660 and then incident into the human eye E. In this way, the human eye E can see a picture composed of polarized light (in FIG. 2B, the dashed line with an arrow represents the propagation path of the light emitted by the display substrate 1100).

[0046] It should be understood that the type of the display device 1000 provided by the embodiments of the present disclosure is not limited to liquid crystal display devices, direct display devices, and 3D display devices, and any other suitable type of display device can be considered, as long as the same technical idea is adopted, and the embodiments of the present disclosure will not be listed one by one.

[0047] In some embodiments, referring to FIG. 3 and FIG. 4, a display substrate 1100 is provided in embodiments of the present disclosure. The display substrate 1100 has a light-outgoing side and a non-light-outgoing side. The display substrate 1100 further includes a first substrate 100 and a plurality of light-emitting devices 200 disposed on the first substrate 100.

[0048] Exemplarily, the first substrate 100 can include a driving circuit layer (not shown in the figures), and the first substrate 100 can also be referred to as an array substrate. The light-emitting devices 200 can be mounted on the first substrate 100 in a normal way. Alternatively, the light-emitting devices 200 can also be mounted on the first substrate 100 in a flip-chip way. The light-emitting devices 200 are connected with the driving circuit layer of the first substrate 100 and emit light under the control of the driving circuit layer.

[0049] Exemplarily, the driving circuit layer can include, but is not limited to, a thin film transistor (TFT) and a power voltage signal line. The thin film transistor is used to form a driving circuit to drive the light-emitting devices 200 to emit light. The driving circuit layer can include a plurality of conductive layers and an insulating layer between adjacent conductive layers, and the conductive layers can be connected through a via hole penetrating the insulating layer to transmit signals between different conductive layers. Of course, the structure of the first substrate 100 is not limited to this, and can also include other structures such as data lines and gate lines, etc., and embodiments of the present disclosure will not be enumerated one by one as long as the same technical idea is adopted.

[0050] The plurality of light-emitting devices 200 each include a first electrode 21, a first functional layer 22, a quantum dot light-emitting layer 23, a second functional layer 24 and a second electrode 25 stacked in a direction away from the first substrate 100 (from bottom to top in FIG. 3 and FIG. 4).

[0051] Exemplarily, the material of the first electrode 21 is a transparent conductive material, which refers to a material with a light transmittance greater than a preset value (such as 80%, 90% or 95%, etc.). Exemplarily, the material of the first electrode layer 24 can be indium tin oxide (ITO).

[0052] The first functional layer 22 can be a hole transport layer (HTL), and the second functional layer 24 can be an electron transport layer (ETL). The first functional layer 22 and the second functional layer 24 can be formed of the same or similar materials, for example, including but not limited to: PEDOT [poly(ethylene dioxythiophene)], PEDOT:PSS [poly(ethylene dioxythiophene)-poly(styrenesulfonate)], TFB [poly{9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine}], zinc oxide or magnesium zinc oxide, and a composite material of each of the above materials. The quantum dot light-emitting layer 23 can include a quantum dot (QD) material.

[0053] The plurality of light-emitting devices 200 includes at least two types of light-emitting devices 200, one type of light-emitting device is configured to emit light of one color, and the thicknesses of the first electrodes 21 of the at least two types of light-emitting devices 200 are different. Taking a light-emitting device 200 that emits light of the same color as one type of light-emitting device, the inventors have found that for the same type of light-emitting device, the thickness of the first electrode 21 affects the light-emitting efficiency thereof, that is, the light-emitting efficiency of the light-emitting device 200 is different for different thicknesses of the first electrode 21. Moreover, for different types of light-emitting devices, the light-emitting efficiency of the same thickness of the first electrode 21 is also different, and the thickness of the first electrode 21 corresponding to the optimal light-emitting efficiency of different types of light-emitting devices is different. In the basic application, the thicknesses of the first electrodes 21 of the at least two types of light-emitting devices 200 are different, and based thereon, the thickness of the first electrode 21 can be adjusted to make each type of light-emitting device 200 achieve a higher light-emitting efficiency, thereby improving the overall light-emitting efficiency of the display substrate.

[0054] In some embodiments, referring to FIG. 3, the first electrode 21 is farther away from the light-emitting side than the second electrode 25, that is, the display substrate 1100 is a top-emission display substrate, and the light-emitting device 200 emits light in a direction away from the first substrate 100.

[0055] As shown in FIG. 3, in the case where the display substrate 1100 is a top-emission display substrate, the light-emitting device 200 further includes a reflective layer 26 located on the side of the first electrode 21 close to the first substrate 100, and the reflective layer 26 is configured to reflect light emitted by the light-emitting device 200 toward the side of the first substrate 100, so as to improve the brightness of the light-emitting side of the light-emitting device 200. The second electrode 25 can include a transparent conductive material, for example, the material of the second electrode 25 includes magnesium-silver alloy, and the thickness of the magnesium-silver alloy can be about 10 nm.

[0056] In some embodiments, referring to FIG. 3, the plurality of light emitting devices 200 can include a red light emitting device 210, a green light emitting device 220, and a blue light emitting device 230. Among them, the red light emitting device 210 refers to a light emitting device configured to emit red light, and similarly, the green light emitting device 220 refers to a light emitting device configured to emit green light, and the blue light emitting device 230 refers to a light emitting device configured to emit blue light. In order to facilitate the description of the first electrode 21 of the red light emitting device 210, the green light emitting device 220, and the blue light emitting device 230, the first electrode 21 included in the red light emitting device 210, the green light emitting device 220, and the blue light emitting device 230 is respectively marked as 211, 212, and 213, that is, the first electrode 211 of the red light emitting device 210, the first electrode 212 of the green light emitting device 220, and the first electrode 213 of the blue light emitting device 230. In addition, in order to facilitate the differentiation of the red light emitting device 210, the green light emitting device 220, and the blue light emitting device 230, the quantum dot light emitting layer of the red light emitting device 210, the green light emitting device 220, and the blue light emitting device 230 is respectively marked as R-QD, G-QD, and B-QD in the drawings.

[0057] In some embodiments, the thickness of the reflective layer 26 belonging to the red light emitting device 210, the green light emitting device 220, and the blue light emitting device 230, respectively, can be equal. Exemplarily, the reflective layer 26 belonging to the red light emitting device 210, the green light emitting device 220, and the blue light emitting device 230, respectively, can include the same material and be arranged in the same layer.

[0058] FIG. 5 is a curve diagram of the luminous brightness of a light emitting device under different thicknesses of the first electrode, in which the abscissa is the thickness of the first electrode 21, in units of nm; the ordinate is the light intensity (normalized) of the light emitting device relative to the front surface, which can also be referred to as the luminance, in units of relative units a.u.. Among them, the curve diagram shown in FIG. 5 is obtained by Setfos software simulation based on the structure of the light emitting device as follows: the first substrate 100 adopts a glass substrate with a thickness of 0.5 mm, the reflective layer 26 adopts silver (Ag) with a thickness of 200 nm, the material of the first electrode 21 is ITO, the hole transport layer 22 adopts a 30 nm PEDOT and 25 nm TFB stacked structure, the thickness of the quantum dot light emitting layer 23 is 20 nm, the electron transport layer 24 adopts zinc magnesium oxide (ZnmgO) with a thickness of 50 nm, and the second electrode 25 adopts a magnesium-silver alloy (Mg:Ag) with a thickness of 10 nm.

[0059] Referring to FIG. 3 and FIG. 5, the thickness of the first electrode 211 of the red light emitting device 210 is less than the thickness of the first electrode 213 of the blue light emitting device 230, and the thickness of the first electrode 213 of the blue light emitting device 230 is less than the thickness of the first electrode 212 of the green light emitting device 220. In other words, the thickness of the first electrode 21 of the red light emitting device 210, the blue light emitting device 230 and the green light emitting device 220 increases. Referring to FIG. 5, the inventor finds that the thickness of the first electrode 21 of the red light emitting device 210, the blue light emitting device 230 and the green light emitting device 220 increases when the red light emitting device 210, the blue light emitting device 230 and the green light emitting device 220 have higher light emitting brightness, and the above design is beneficial to the red light emitting device 210, the blue light emitting device 230 and the green light emitting device 220 having higher light emitting efficiency, thereby improving the light emitting efficiency of the display substrate.

[0060] In some embodiments, as shown in FIG. 3 and FIG. 5, the thickness of the first electrode 211 of the red light emitting device 210 can be 10nm-20nm, or the thickness of the first electrode 211 of the red light emitting device 210 can be 170nm-180nm. In this case, the brightness of the red light emitting device 210 can reach a higher level. However, the inventor finds that although the thickness of the first electrode 211 of the red light emitting device 210 is less than 10nm, the light emitting brightness of the red light emitting device 210 will not be significantly reduced, but the thickness of the first electrode 211 is too small (such as less than 10nm), which can cause the problem of yield reduction. In addition, when the thickness of the first electrode 211 is greater than 150nm, the first electrode 211 may cause etching residue during the preparation process of the first electrode 211, thereby affecting the yield of the red light emitting device 210. Therefore, in the embodiments of the present disclosure, the thickness of the first electrode 211 of the red light emitting device 210 can be 10nm-20nm, so that the light emitting brightness of the red light emitting device 210 can reach a higher level, and the yield of the red light emitting device 210 can be guaranteed, thereby improving the product yield of the display substrate.

[0061] For example, when the thickness of the first electrode 211 of the red light emitting device 210 is 10nm-20nm, the light emitting brightness of the red light emitting device 210 can reach 0.8 or more. The thickness of the first electrode 211 of the red light emitting device 210 can be 10nm-15nm, or the thickness of the first electrode 211 of the red light emitting device 210 can be 15nm-20nm. For example, the thickness of the first electrode 211 of the red light emitting device 210 can be 10nm, 13nm, 15nm, 17nm or 20nm, and the embodiments of the present disclosure will not be listed one by one.

[0062] It should be noted that in some other cases, on the basis of the embodiments of the present disclosure, the thickness of the first electrode 211 of the red light emitting device 210 can also be greater than 20 nm, for example, the thickness of the first electrode 211 of the red light emitting device 210 can also be 20 nm to 25 nm, at the premise of sacrificing the luminous intensity of the red light emitting device 210.

[0063] In some embodiments, as shown in FIGS. 3 and 5, the thickness of the first electrode 213 of the blue light emitting device 230 can be 65 nm to 75 nm, or the thickness of the first electrode 213 of the blue light emitting device 230 can be 180 nm to 190 nm. In this case, the luminance of the blue light emitting device 230 can reach a high level. However, the inventors have found that when the thickness of the first electrode 211 is greater than 150 nm, etching residues may occur in the first electrode 211 during the preparation of the first electrode 211, thereby affecting the yield of the blue light emitting device 230. Therefore, in the embodiments of the present disclosure, the thickness of the first electrode 213 of the blue light emitting device 230 can be 65 nm to 75 nm, so that the luminous intensity of the blue light emitting device 230 can reach a high level, and the yield of the blue light emitting device 230 can be guaranteed, thereby being conducive to improving the product yield of the display substrate.

[0064] Exemplarily, when the thickness of the first electrode 213 of the blue light emitting device 230 is 65 nm to 75 nm, the luminous intensity of the blue light emitting device 230 can reach 0.9 or more. For example, the thickness of the first electrode 213 of the blue light emitting device 230 can be 65 nm to 70 nm, or the thickness of the first electrode 213 of the blue light emitting device 230 can be 70 nm to 75 nm. For example, the thickness of the first electrode 213 of the blue light emitting device 230 can be 65 nm, 67 nm, 70 nm, 73 nm, or 75 nm, and the like, and the embodiments of the present disclosure will not be enumerated one by one.

[0065] In some embodiments, as shown in FIG. 3 and FIG. 5, the thickness of the first electrode 212 of the green light emitting device 220 can be 0 nm to 10 nm. Alternatively, the thickness of the first electrode 212 of the green light emitting device 220 can be 120 nm to 130 nm. In this case, the luminance of the green light emitting device 220 can reach a high level. However, the inventors have found that when the thickness of the first electrode 212 is less than 10 nm, the first electrode 212 may

[0066] Exemplarily, when the thickness of the first electrode 212 of the green light emitting device 220 is 120 nm to 130 nm, the luminance of the green light emitting device 220 can reach 0.9 or more. For example, the thickness of the first electrode 212 of the green light emitting device 220 can be 120 nm to 125 nm, or the thickness of the first electrode 212 of the green light emitting device 220 can be 125 nm to 130 nm. For example, the thickness of the first electrode 212 of the green light emitting device 220 can be 120 nm, 123 nm, 125 nm, 129 nm, or 130 nm, and the like, which will not be enumerated one by one in the embodiments of the present disclosure.

[0067] In some embodiments, referring to FIG. 4, the first electrode 21 is closer to the light emitting side than the second electrode 25, that is, the display substrate 1100 is a bottom emission display substrate, and the light emitting device 200 emits light along the side close to the first substrate 100, and the light is emitted after passing through the first substrate 100.

[0068] In the case of the display substrate 1100 being a bottom emission display substrate, the material of the first electrode 21 can be a transparent conductive material, which refers to a material with a light transmittance greater than a preset value (such as 80%, 90%, or 95%, and the like). Exemplarily, the material of the first electrode layer 24 can be indium tin oxide (English: Indium Tin Oxide; abbreviated: ITO). The second electrode 25 can be a light reflecting material, for example, the material of the second electrode 25 can be aluminum. In one example, the second electrode 25 adopts aluminum with a thickness of about 100 nm.

[0069] In some embodiments, referring to FIG. 4, the plurality of light emitting devices 200 can include a red light emitting device 210, a green light emitting device 220, and a blue light emitting device 230. Among them, the red light emitting device 210 refers to a light emitting device configured to emit red light, and similarly, the green light emitting device 220 refers to a light emitting device configured to emit green light, and the blue light emitting device 230 refers to a light emitting device configured to emit blue light. In order to facilitate the description of the first electrode 21 of the red light emitting device 210, the green light emitting device 220, and the blue light emitting device 230, the first electrode 21 included in the red light emitting device 210, the green light emitting device 220, and the blue light emitting device 230 is respectively marked as 211, 212, and 213, that is, the first electrode 211 of the red light emitting device 210, the first electrode 212 of the green light emitting device 220, and the first electrode 213 of the blue light emitting device 230.

[0070] FIG. 6 is a curve diagram of the light emitting efficiency of the light emitting device under different thicknesses of the first electrode, in which the abscissa is the thickness of the first electrode 21, and the unit is nm; the ordinate is the light emitting efficiency of the light emitting device. Among them, the curve diagram shown in FIG. 5 is obtained by Setfos software simulation based on the structure of the light emitting device: the first substrate 100 adopts a glass substrate with a thickness of 0.5 mm, the material of the first electrode 21 is ITO, the hole transport layer 22 adopts a 25 nm PEDOT and a 23 nm TFB stacked structure, the thickness of the quantum dot light emitting layer 23 is 20 nm, the electron transport layer 24 adopts a 50 nm zinc magnesium oxide (ZnMgO), and the second electrode 25 adopts a 100 nm magnesium-silver alloy (Mg:Ag).

[0071] Referring to FIGS. 4 and 6, the thickness of the first electrode 211 of the red light emitting device 210 is greater than the thickness of the first electrode 212 of the green light emitting device 220, and the thickness of the first electrode 212 of the green light emitting device 220 is greater than the thickness of the first electrode 213 of the blue light emitting device 230. In other words, the thicknesses of the first electrodes 21 of the red light emitting device 210, the green light emitting device 220, and the blue light emitting device 230 decrease. Referring to FIG. 6, the inventors have found that the thicknesses of the first electrodes 21 of the red light emitting device 210, the blue light emitting device 230, and the green light emitting device 220 decrease when they have higher light emitting efficiency. The above design is beneficial to the red light emitting device 210, the green light emitting device 220, and the blue light emitting device 230 all having higher light emitting efficiency, thereby improving the light emitting efficiency of the display substrate.

[0072] In some embodiments, as shown in FIGS. 4 and 6, the thickness of the first electrode 211 of the red light emitting device 210 can be 130 nm to 150 nm. In this case, the luminance of the red light emitting device 210 can reach a high level. In the case that the thickness of the first electrode 211 is greater than 150 nm, the first electrode 211 can have etching residue in the preparation process of the first electrode 211, thereby affecting the yield of the red light emitting device 210. Therefore, in the embodiments of the present disclosure, the thickness of the first electrode 211 of the red light emitting device 210 can be 130 nm to 150 nm, so that the luminance of the red light emitting device 210 can reach a high level, and the yield of the red light emitting device 210 can be ensured, thereby facilitating the improvement of the product yield of the display substrate.

[0073] For example, in the case that the thickness of the first electrode 211 of the red light emitting device 210 is 120 nm to 150 nm, the light extraction efficiency of the red light emitting device 210 can reach more than 23%. The thickness of the first electrode 211 of the red light emitting device 210 can be 130 nm to 140 nm, or the thickness of the first electrode 211 of the red light emitting device 210 can be 140 nm to 150 nm. For example, the thickness of the first electrode 211 of the red light emitting device 210 can be 130 nm, 133 nm, 140 nm, 145 nm, 147 nm or 150 nm, and the like, and the embodiments of the present disclosure will not be enumerated one by one.

[0074] It should be noted that in other cases, on the basis of the embodiments of the present disclosure, the thickness of the first electrode 211 of the red light emitting device 210 can be greater than 20 nm on the premise of sacrificing a certain luminance of the red light emitting device 210, for example, the thickness of the first electrode 211 of the red light emitting device 210 can be 20 nm to 25 nm.

[0075] In some embodiments, as shown in FIGS. 4 and 6, the thickness of the first electrode 213 of the blue light emitting device 230 can be 60 nm to 70 nm. In this case, the luminance of the blue light emitting device 230 can reach a high level, and the yield of the blue light emitting device 230 can be ensured, thereby facilitating the improvement of the product yield of the display substrate.

[0076] For example, in the case that the thickness of the first electrode 213 of the blue light emitting device 230 is 60 nm to 70 nm, the light extraction efficiency of the blue light emitting device 230 can reach more than 25%.

[0077] For example, the thickness of the first electrode 213 of the blue light emitting device 230 can be 60nm-65nm, or the thickness of the first electrode 213 of the blue light emitting device 230 can be 65nm-70nm. For example, the thickness of the first electrode 213 of the blue light emitting device 230 can be 60nm, 62nm, 65nm, 68nm or 70nm, and the like, and the embodiments of the present disclosure will not be listed one by one.

[0078] In some embodiments, as shown in FIGS. 4 and 6, the thickness of the first electrode 212 of the green light emitting device 220 can be 90nm-110nm. In this case, the brightness of the green light emitting device 220 can reach a high level, and the yield of the green light emitting device 220 can also be ensured, thereby facilitating the improvement of the product yield of the display substrate.

[0079] For example, the thickness of the first electrode 212 of the green light emitting device 220 can be 90nm-100nm, or the thickness of the first electrode 212 of the green light emitting device 220 can be 100nm-110nm. For example, the thickness of the first electrode 212 of the green light emitting device 220 can be 90nm, 95nm, 100nm, 105nm or 110nm, and the like, and the embodiments of the present disclosure will not be listed one by one.

[0080] In some embodiments, referring to FIGS. 3 and 4, in the case that the display substrate 1100 is a top emission type display substrate or a bottom emission type display substrate, the thicknesses of the first functional layer 22, the second functional layer 24 and the second electrode 25 belonging to the red light emitting device 210, the green light emitting device 220 and the blue light emitting device 230, respectively, correspond to each other. In this way, the first functional layer 22, the second functional layer 24 and the second electrode 25 belonging to the red light emitting device 210, the green light emitting device 220 and the blue light emitting device 230, respectively, can be made of the same material and arranged in the same layer, which is beneficial to simplify the preparation process of the display substrate and thereby reduce the preparation cost of the display substrate.

[0081] In some embodiments, the inventors of the present application also experimentally verified the influence of the first electrode with different thicknesses in the above embodiments on the light emitting efficiency of the light emitting device. Referring to FIGS. 7-9, the embodiments of the present application are exemplarily tested by taking a bottom emission display substrate and a green light emitting device with multiple first electrodes with different thicknesses as an example. Among them, the green light emitting device is arranged on the first substrate in an upright structure. Of course, the green light emitting device can also be arranged on the first substrate in an inverted structure.

[0082] A green light emitting device can be formed by a preparation method as follows. The preparation method can include S11-S18.

[0083] S11, providing a substrate of a bottom emission structure, and cleaning the substrate of the bottom emission structure.

[0084] S12, forming a first electrode with different thicknesses on the substrate, and cleaning the substrate.

[0085] In an embodiment of the present disclosure, the first electrode is formed by ITO material, and the thickness of the first electrode is 60 nm, 100 nm, 135 nm and 185 nm respectively. The cleaning process of the substrate can include, for example, cleaning the substrate with deionized water for 10 min, cleaning the substrate with deionized water again for 10 min, cleaning the substrate with isopropyl alcohol for 10 min, drying the substrate with nitrogen, and baking the substrate on an oven or a heating platform at a temperature of 100-150°C for 5 min.

[0086] S13, forming a hole injection layer on the substrate.

[0087] The material of the hole injection layer can include, but is not limited to, PEDOT:PSS, NiO, MoO3, etc., and the preparation process of the hole injection layer can include, but is not limited to, spin coating, slot coating, blade coating, inkjet printing, and evaporation process. In the verification test conducted in the present disclosure, the hole injection layer is formed by spin coating process and PEDOT:PSS material, the thickness of PEDOT:PSS is about 15-40 nm, and the baking is performed at 150°C for 10-30 min.

[0088] S14, forming a hole transport layer on the hole injection layer.

[0089] The material of the hole transport layer can include, but is not limited to, TFB, PF8Cz, PVK, etc. The preparation process of the hole transport layer can include, but is not limited to, spin coating, slot coating, blade coating, and inkjet printing process. In the verification test conducted in the present disclosure, the hole transport layer is formed by spin coating process and TFB material, the thickness of TFB is about 15-40 nm, and the baking is performed at 130°C for 20-30 min.

[0090] S15, forming a quantum dot light emitting layer on the hole transport layer.

[0091] In the present embodiment, the quantum dot light emitting layer is formed by spin coating process, and the thickness of the quantum dot light emitting layer is about 10-30 nm. Of course, in the actual preparation process, the light emitting layer can also be patterned by inkjet printing or photolithography patterning process.

[0092] S16, forming an electron transport layer on the quantum dot.

[0093] Exemplarily, the material of the electron transport layer includes, but is not limited to, ZnO and ZnMgO. In the verification test conducted in the present disclosure, the electron transport layer is prepared by a spin coating process and is formed by using ZnMgO material, the thickness of the ZnMgO material is about 30 nm to 90 nm, and the baking is performed at 80-120°C for 10 min.

[0094] S17, preparing a second electrode on the electron transport layer.

[0095] In the verification test conducted in the present disclosure, the second electrode is prepared by a vapor deposition process (evaporation rate ) and is formed by using aluminum vapor deposition, the thickness of the second electrode layer is 100 nm.

[0096] S18, packaging the plurality of light emitting devices.

[0097] Exemplarily, the SiO / SiON / SiN thin film can be used to encapsulate the organic glue material, or a glass cover plate and ultraviolet curing glue can be used for encapsulation.

[0098] The experimental results shown in FIGS. 7-9 are based on the light emitting devices prepared by the above process. It should be noted that when the structure of the light emitting device is changed or the process for preparing the light emitting device is changed, it may have some influence on the experimental results; other equivalent condition changes that can be thought of by those skilled in the art under the above disclosed experimental conditions should be within the protection scope of the present application.

[0099] FIG. 7 is a curve diagram of the voltage and current density of the light emitting device, wherein the horizontal coordinate is the voltage applied to the first electrode, in units of volts (V); the vertical coordinate is the current density of the light emitting device, in units of milliampere per square centimeter (mA / cm 2 ). FIG. 8 is a curve diagram of the voltage and luminous intensity of the light emitting device, wherein the horizontal coordinate is the voltage applied to the first electrode, in units of volts (V); the vertical coordinate is the luminous intensity of the light emitting device, in units of candela per square meter (cd / m 2 ). FIG. 9 is a curve diagram of the voltage and external quantum efficiency (EQE) of the light emitting device, wherein the horizontal coordinate is the voltage applied to the first electrode, in units of volts (V); the vertical coordinate is the external quantum efficiency of the light emitting device.

[0100] Referring to FIG. 7, from the voltage and current density curves of the light-emitting device, it can be seen that the thickness of the first electrode directly affects the sheet resistance of the first electrode. For example, under the same preparation process, the greater the thickness of the first electrode, the smaller the sheet resistance of the first electrode, the greater the current density on the first electrode, and the stronger the conductive ability of the first electrode. In particular, under high voltage (for example, 5V-6V), the current density of the light-emitting device with different thicknesses of the first electrode is obviously different. For example, the current density of the light-emitting device with a thickness of 185 nm of the first electrode is obviously greater than the current density of the light-emitting device with a thickness of 60 nm of the first electrode.

[0101] Referring to FIG. 8, from the voltage and luminous intensity curves of the light-emitting device, it can be seen that the luminous intensity of the light-emitting device is not the greater the thickness of the first electrode, the better, nor the smaller the thickness of the first electrode, the better. For example, under the same other structure of the light-emitting device, the luminous intensity of the light-emitting device with a thickness of 100 nm of the first electrode is greater than the luminous intensity of the light-emitting device with a thickness of 60 nm of the first electrode, and greater than the luminous intensity of the light-emitting device with a thickness of 130 nm and 185 nm of the first electrode. Obviously, for the light-emitting device, the thickness of the first electrode can affect the luminous intensity of the light-emitting device.

[0102] Referring to FIG. 9, from the voltage and external quantum efficiency curves of the light-emitting device, it can be seen that, in combination with the current density and luminous intensity trends of the light-emitting device, when the thickness of the first electrode of the light-emitting device is 100, the current density of the green quantum dot light-emitting device is not the highest, but it can obtain the highest luminous intensity, so it shows the highest external quantum efficiency, and the change trend of the external quantum efficiency of the light-emitting device with different thicknesses of the first electrode is consistent with the result of the optical simulation.

[0103] By comprehensively comparing the data obtained by the above optical simulation and actual measurement, it can be seen that the performance of the light-emitting device under different thicknesses of the first electrode conforms to the result of the above optical simulation. Based on this, it can be considered that the difference in the light-emitting efficiency of the light-emitting device described in the above embodiments under different thicknesses of the first electrode is correct.

[0104] Some embodiments of the present disclosure also disclose a preparation method of a display substrate, and the preparation method comprises S20-S50.

[0105] S20, forming a conductive layer on a first substrate. The conductive layer covers the first substrate.

[0106] S30, forming a mask layer on the conductive layer. The mask layer covers part of the conductive layer.

[0107] S40, patterning the conductive layer according to the mask layer, wherein a plurality of first electrodes are formed.

[0108] The steps S20-S40 are repeated to form at least two patterned conductive layers, and thicknesses of the at least two patterned conductive layers are not equal. In this way, at least two first electrodes with different thicknesses can be formed.

[0109] S50, continue to prepare the light-emitting device on the at least two first electrodes with different thicknesses.

[0110] Exemplarily, the light-emitting device with the first electrode with different thicknesses is configured to emit light with different colors. That is, in the embodiment of the present disclosure, the first electrodes with different thicknesses of the plurality of light-emitting devices are prepared by the multi-film forming process and the patterning process, so that the thickness of the first electrode corresponding to each light-emitting device can be accurately controlled, so that the light-emitting efficiency of each light-emitting device is in a relatively high range.

[0111] In some embodiments, in the case where the display substrate 1100 includes a red light-emitting device 210, a green light-emitting device 220, and a blue light-emitting device 230. The red light-emitting device 210, the green light-emitting device 220, and the blue light-emitting device 230 each include a first electrode 21, and the thicknesses of the first electrodes belonging to the red light-emitting device 210, the green light-emitting device 220, and the blue light-emitting device 230 are not equal. At this time, the preparation method of the display substrate includes S201-S401, S202-S402, S203-S403, and S60.

[0112] S201, referring to FIG. 10A, a first conductive layer ITO1 is formed on a first substrate 100.

[0113] The first conductive layer ITO1 covers the first substrate 100, and the structure and function of the first substrate 100 are described above and will not be repeated here. Exemplarily, the first conductive layer ITO1 can be prepared by a sputtering process.

[0114] S301, referring to FIG. 10A, a first mask layer M1 is formed on the first conductive layer ITO1.

[0115] The first mask layer M1 covers part of the first conductive layer ITO1. Exemplarily, the first mask layer M1 can cover the region of the first conductive layer ITO1 used to form the first sub-electrode. The first mask layer M1 can include, but is not limited to, a photoresist formed by coating, exposure, and development processes.

[0116] S401, referring to FIG. 10B, the first conductive layer ITO is patterned according to the first mask layer M1 to form a plurality of first sub-electrodes 214.

[0117] Exemplarily, the first conductive layer ITO can be prepared by an etching process to remove the regions of the first conductive layer ITO not covered by the first mask layer M1, and the portions of the first conductive layer ITO not removed by the etching process form the first sub-electrode 214.

[0118] S202, referring to FIG. 10C, a second conductive layer ITO2 is formed on the first substrate 100.

[0119] Exemplarily, the second conductive layer ITO2 covers the first mask layer M1 and the regions of the first substrate 100 not covered by the first sub-electrode 214, that is, the second conductive layer ITO2 is a continuous whole layer structure. For example, the second conductive layer ITO2 can be prepared by a sputtering process.

[0120] S302, referring to FIG. 10C, a second mask layer M2 is formed on the second conductive layer ITO2.

[0121] The second mask layer M2 covers part of the second conductive layer ITO2. Exemplarily, the second mask layer M2 covers the regions of the second conductive layer ITO2 for forming the second sub-electrode 215. The second mask layer M2 also exposes at least the regions of the second conductive layer ITO2 covering the first mask layer M1, so that the second conductive layer ITO2 of the regions can be removed in a subsequent process of patterning the second mask layer M2. Exemplarily, the second mask layer M2 can include, but is not limited to, a photoresist formed by coating, exposure and development processes.

[0122] S402, referring to FIG. 10D, the second conductive layer ITO2 is patterned according to the second mask layer M2 to form a plurality of second sub-electrodes 215.

[0123] Exemplarily, the second conductive layer ITO2 can be prepared by an etching process to remove the regions of the second conductive layer ITO2 not covered by the second mask layer M2, and the portions of the second conductive layer ITO2 not removed by the etching process (the portions covered by the second mask layer M2) are retained and form the second sub-electrodes 215.

[0124] S203, referring to FIG. 10E, a third conductive layer ITO3 is formed on the first substrate 100.

[0125] The third conductive layer ITO3 covers the first mask layer M1, the second mask layer M2 and the regions of the first substrate 100 not covered by the first mask layer M1 and the second mask layer M2. That is, the third conductive layer ITO3 is a continuous whole layer structure. For example, the third conductive layer ITO3 can be prepared by a sputtering process.

[0126] S303, referring to FIG. 10E, a third mask layer M3 is formed on the third conductive layer ITO3.

[0127] The third mask layer M3 covers part of the third conductive layer ITO3. Illustratively, the third mask layer M3 covers the region of the third conductive layer ITO3 for forming the third sub-electrode 216. Moreover, the third mask layer M3 exposes at least the part of the third conductive layer ITO3 covering the first mask layer M1 and the second mask layer M2, so as to facilitate removal of the third conductive layer ITO3 on the first mask layer M1 and the second mask layer M2 in the subsequent patterning process of the third conductive layer ITO3. Illustratively, the second mask layer M2 can include, but is not limited to, photoresist formed by coating, exposure and development processes, etc.

[0128] S403, referring to FIG. 10F, the third conductive layer ITO3 is patterned according to the third mask layer M3 to form a plurality of third sub-electrodes 216.

[0129] Illustratively, the region of the third conductive layer ITO3 not covered by the third mask layer M3 can be removed by an etching process, and the part of the third conductive layer ITO3 not removed by etching (the part covered by the second mask layer M2) is retained and forms the third sub-electrode 216.

[0130] S60, referring to FIG. 10G, the first mask layer M1, the second mask layer M2 and the third mask layer M3 are removed.

[0131] In some embodiments, the thicknesses of the first conductive layer ITO1, the second conductive layer ITO2 and the third conductive layer ITO3 are different. The specific value range of the thicknesses of the first conductive layer ITO1, the second conductive layer ITO2 and the third conductive layer ITO3 can refer to the corresponding thickness range of the first electrode of the red sub-pixel, the green sub-pixel and the blue sub-pixel described above, which will not be described again in detail in the embodiments of the present disclosure. One of the first sub-electrode 214, the second sub-electrode 215 and the third sub-electrode 216 is configured to form the first electrode 211 of the red light emitting device 210, another is configured to form the first electrode 212 of the green light emitting device 220, and the other is configured to form the first electrode 213 of the blue light emitting device 230. The thicknesses of the first sub-electrode 214, the second sub-electrode 215 and the third sub-electrode 216 are different.

[0132] In one embodiment, the thicknesses of the first sub-electrode 214, the second sub-electrode 215 and the third sub-electrode 216 can decrease in turn, that is, the first electrode with a larger thickness is prepared first, which is beneficial to resist etching of the first electrode prepared first in the process of preparing the subsequent first electrode, and is beneficial to improve the yield of the light emitting device. Of course, the embodiments of the present disclosure are not necessarily limited thereto, and the first electrode 211 of the red light emitting device 210, the first electrode 212 of the green light emitting device 220 and the first electrode 213 of the blue light emitting device 230 can be prepared in any order, respectively.

[0133] The above description is merely that of a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who thinks of changes or replacements within the technical scope disclosed by the present disclosure should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A display substrate having a light-emitting side and a non-light-emitting side; the display substrate further comprising: A first substrate and a plurality of light-emitting devices disposed on the first substrate; Each of the plurality of light-emitting devices includes a first electrode, a first functional layer, a quantum dot light-emitting layer, a second functional layer, and a second electrode stacked along a direction away from the first substrate; The plurality of light-emitting devices include at least two types of light-emitting devices, one of which is configured to emit light of a certain color, and the thickness of the first electrode included in the at least two types of light-emitting devices is not equal.

2. The display substrate according to claim 1, wherein, The first electrode is farther away from the light-emitting side than the second electrode; The plurality of light-emitting devices include a red light-emitting device, a green light-emitting device, and a blue light-emitting device; the thickness of the first electrode of the red light-emitting device is less than the thickness of the first electrode of the blue light-emitting device; the thickness of the first electrode of the blue light-emitting device is less than the thickness of the first electrode of the green light-emitting device.

3. The display substrate according to claim 2, wherein, The thickness of the first electrode of the red light-emitting device is 10 nm to 20 nm; and / or, The thickness of the first electrode of the blue light-emitting device is 65nm to 75nm; and / or, The thickness of the first electrode of the green light-emitting device is 120nm to 130nm.

4. The display substrate according to claim 2 or 3, wherein, The light-emitting device further includes a reflective layer located on the side of the first electrode near the first substrate; the reflective layers belonging to the red light-emitting device, the green light-emitting device, and the blue light-emitting device have equal thicknesses.

5. The display substrate according to claim 1, wherein, The first electrode is closer to the light-emitting side than the second electrode; The plurality of light-emitting devices include a red light-emitting device, a green light-emitting device, and a blue light-emitting device; the thickness of the first electrode of the red light-emitting device is greater than the thickness of the first electrode of the green light-emitting device; the thickness of the first electrode of the green light-emitting device is greater than the thickness of the first electrode of the blue light-emitting device.

6. The display substrate according to claim 5, wherein, The thickness of the first electrode of the red light-emitting device is 130nm to 150nm; and / or, The thickness of the first electrode of the blue light-emitting device is 60 nm to 70 nm; and / or, The thickness of the first electrode of the green light-emitting device is 90nm to 110nm.

7. The display substrate according to any one of claims 2 to 6, wherein, The thicknesses of the first functional layer, the second functional layer, and the second electrode belonging to the red light-emitting device, the green light-emitting device, and the blue light-emitting device, respectively, are equal.

8. The display substrate according to any one of claims 1 to 7, wherein, The material of the first electrode includes a transparent conductive material.

9. A display device, comprising: The display substrate as described in any one of claims 1 to 8; A driver circuit board, electrically connected to the display substrate, is configured to transmit control signals to the display substrate.

10. A method for preparing a display substrate, comprising: A conductive layer is formed on a first substrate, the conductive layer covering the first substrate; A mask layer is formed on the conductive layer, and the mask layer covers a portion of the conductive layer; The conductive layer is patterned according to the mask layer to form a plurality of first electrodes; Repeat the above steps to form at least two patterned conductive layers, the thickness of which is not equal.

11. The method for preparing a display substrate according to claim 10, wherein, The display substrate includes a red light-emitting device, a green light-emitting device, and a blue light-emitting device, wherein the red light-emitting device, the green light-emitting device, and the blue light-emitting device include first electrodes of different thicknesses; The preparation method includes: A first conductive layer is formed on a first substrate, and the first conductive layer covers the first substrate; A first mask layer is formed on the first conductive layer, and the first mask layer covers a portion of the first conductive layer; The first conductive layer is patterned according to the first mask layer to form a plurality of first sub-electrodes; A second conductive layer is formed on the first substrate, the second conductive layer covering the first mask layer and the area on the first substrate not covered by the first sub-electrode; A second mask layer is formed on the second conductive layer, the second mask layer covering a portion of the second conductive layer and at least exposing the area in the second conductive layer that covers the first mask layer; The second conductive layer is patterned according to the second mask layer to form a plurality of second sub-electrodes; A third conductive layer is formed on the first substrate, the third conductive layer covering the first mask layer, the second mask layer, and the area in the first substrate not covered by the first mask layer and the second mask layer; A third mask layer is formed on the third conductive layer, the third mask layer covering a portion of the third conductive layer, and at least exposing the portions of the third conductive layer that cover the first mask layer and the second mask layer; The third conductive layer is patterned according to the third mask layer to form a plurality of third sub-electrodes; Remove the first mask layer, the second mask layer, and the third mask layer; In this configuration, one of the first sub-electrode, the second sub-electrode, and the third sub-electrode is configured to form the first electrode of the red light-emitting device, another is configured to form the first electrode of the green light-emitting device, and yet another is configured to form the first electrode of the blue light-emitting device. The thicknesses of the first sub-electrode, the second sub-electrode, and the third sub-electrode are not equal.

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