Display substrate and its preparation method, display device

Abstract

A display substrate and its fabrication method, and a display device, wherein the display substrate includes a substrate (10) and sub-pixels located on the substrate (10), the sub-pixels include light-emitting devices (20), the light-emitting devices (20) include an anode layer (21), a light-emitting material layer (24), an electron transport layer (25), an electron injection layer (26), and a cathode layer (28); the light-emitting devices (20) include at least one electron injection layer (26), and the light-emitting devices (20) further include at least one high-resistivity layer (27); the high-resistivity layer (27) includes a first high-resistivity film layer (271), and a layer located on the first high-resistivity film layer (271). At least one second high-impedance film layer (272) between the cathode layer (28) and the electron injection layer (26), and at least one third high-impedance film layer (273) between the first high-impedance film layer (271) and the electron injection layer (26); the resistivity of the first high-impedance film layer (271) is greater than the resistivity of the second high-impedance film layer (272) and the resistivity of the third high-impedance film layer (273); the resistivity of the first high-impedance film layer (271), the second high-impedance film layer (272) and the third high-impedance film layer (273) is greater than the resistivity of the cathode layer (28) and the resistivity of the electron injection layer (26).

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to a display substrate, its preparation method, and a display device. Background Technology

[0002] OLED (Organic Light Emitting Diode) is an electroluminescent device that features self-illumination, high luminous efficiency, low operating voltage, thinness, flexibility, and simple manufacturing process. It is widely used in display and lighting fields.

[0003] In related technologies, during the fabrication process of OLED display devices, the presence of microscopic particles within the device cavity can easily cause short circuits in the sub-pixels of the light-emitting area, leading to the generation of dark spots in the light-emitting area and affecting the display effect of the display device. Summary of the Invention

[0004] This application provides a display substrate, a method for fabricating the same, and a display device.

[0005] According to a first aspect of the present application, a display substrate is provided. The display substrate includes a substrate and sub-pixels located on the substrate, the sub-pixels including light-emitting devices;

[0006] The light-emitting device includes an anode layer, a light-emitting material layer, an electron transport layer, an electron injection layer, and a cathode layer arranged sequentially; the light-emitting device includes at least one electron injection layer, and the light-emitting device further includes at least one high-impedance layer, the high-impedance layer being located between the electron injection layer and the cathode layer;

[0007] The high-impedance layer includes a first high-impedance film layer, at least one second high-impedance film layer located between the first high-impedance film layer and the cathode layer, and at least one third high-impedance film layer located between the first high-impedance film layer and the electron injection layer; the resistivity of the first high-impedance film layer is greater than the resistivity of the second high-impedance film layer and the resistivity of the third high-impedance film layer; the resistivity of the first high-impedance film layer, the second high-impedance film layer and the third high-impedance film layer is greater than the resistivity of the cathode layer and the resistivity of the electron injection layer.

[0008] In one embodiment, the thickness of the first high-resistivity film layer is greater than the thickness of the second high-resistivity film layer and the thickness of the third high-resistivity film layer.

[0009] In one embodiment, the thickness of the first high-impedance film layer ranges from 50 nm to 200 nm, the thickness of the second high-impedance film layer ranges from 5 nm to 10 nm, and the thickness of the third high-impedance film layer ranges from 5 nm to 10 nm.

[0010] In one embodiment, when the high impedance layer includes two or more second high impedance film layers, the resistivity of the second high impedance film layer gradually increases in the direction from the cathode layer to the first high impedance film layer within the same high impedance layer.

[0011] In one embodiment, when the high impedance layer includes two or more third high impedance film layers, the resistivity of the third high impedance film layer gradually decreases in the direction from the cathode layer to the first high impedance film layer within the same high impedance layer.

[0012] In one embodiment, the first high-impedance film layer, the second high-impedance film layer, and the third high-impedance film layer are made of the same material.

[0013] In one embodiment, the materials of the first high-resistivity film, the second high-resistivity film, and the third high-resistivity film are selected from at least one of zinc oxide, titanium oxide, tin oxide, and indium oxide.

[0014] In one embodiment, when the number of the electron injection layer and the high impedance layer is greater than or equal to two, the electron injection layer and the high impedance layer are arranged alternately.

[0015] In one embodiment, the resistivity of the first high-impedance film layer is in the range of 10. 4 Ω*cm~10 6 Ω*cm, the resistivity of the second high-resistivity film layer and the third high-resistivity film layer ranges from 10 Ω*cm. 2 Ω*cm~10 3 Ω*cm.

[0016] In one embodiment, the absolute value of the work function of the cathode layer ranges from 3.6 eV to 4.2 eV, the absolute value of the work function of the first high-impedance film layer ranges from 5.2 eV to 6.0 eV, and the absolute value of the work function of the second high-impedance film layer and the third high-impedance film layer ranges from 4.5 eV to 5.2 eV.

[0017] According to a second aspect of the present application, a display substrate is provided. The display substrate includes a substrate, a pixel defining layer and a plurality of sub-pixels located on the substrate;

[0018] The pixel defining layer includes a plurality of first defining portions extending along a first direction and second defining portions extending along a second direction, the first direction intersecting the second direction; the distance from the surface of the first defining portion away from the substrate to the substrate is greater than the distance from the surface of the second defining portion away from the substrate to the substrate; the first defining portions and the second defining portions enclose and form a plurality of pixel openings defining the light-emitting areas of the sub-pixels;

[0019] The sub-pixel includes a light-emitting device, which includes an anode layer, a hole injection layer, a hole transport layer, a light-emitting material layer, an electron transport layer, an electron injection layer, and a cathode layer arranged sequentially. The hole injection layer, hole transport layer, and light-emitting material layer of the sub-pixel are located between two adjacent first limiting portions, and the hole injection layers of multiple sub-pixels located between two adjacent first limiting portions are connected, the hole transport layers of multiple sub-pixels located between two adjacent first limiting portions are connected, and the light-emitting material layers of multiple sub-pixels located between two adjacent first limiting portions are connected.

[0020] The light-emitting device includes at least one electron injection layer and at least one high-impedance layer located between the electron injection layer and the cathode layer. The high-impedance layer includes a first high-impedance film layer, at least one second high-impedance film layer located between the first high-impedance film layer and the cathode layer, and at least one third high-impedance film layer located between the first high-impedance film layer and the electron injection layer. The resistivity of the first high-impedance film layer is greater than the resistivity of the second high-impedance film layer and the resistivity of the third high-impedance film layer. The resistivity of the first high-impedance film layer, the second high-impedance film layer, and the third high-impedance film layer is greater than the resistivity of the cathode layer and the resistivity of the electron injection layer, respectively.

[0021] In one embodiment, the thickness of the first high-resistivity film layer is greater than the thickness of the second high-resistivity film layer and the thickness of the third high-resistivity film layer.

[0022] In one embodiment, when the high-resistivity layer comprises two or more second high-resistivity film layers, within the same high-resistivity layer, the resistivity of the second high-resistivity film layer gradually increases in the direction from the cathode layer to the first high-resistivity film layer; and / or,

[0023] When the high impedance layer includes two or more third high impedance film layers, the resistivity of the third high impedance film layer gradually decreases in the direction from the cathode layer to the first high impedance film layer within the same high impedance layer.

[0024] In one embodiment, the first high-impedance film layer, the second high-impedance film layer, and the third high-impedance film layer are made of the same material.

[0025] In one embodiment, when the number of the electron injection layer and the high impedance layer is greater than or equal to two, the electron injection layer and the high impedance layer are arranged alternately.

[0026] According to a third aspect of the embodiments of this application, a method for preparing a display substrate is provided, the method comprising:

[0027] Provide substrate;

[0028] Forming a light-emitting device located on the substrate;

[0029] The method of forming a light-emitting device on the substrate includes: sequentially forming an anode layer, a light-emitting material layer, an electron transport layer, an electron injection layer, a high-impedance layer, and a cathode layer; the light-emitting device includes at least one electron injection layer and at least one high-impedance layer, wherein the high-impedance layer is located between the electron injection layer and the cathode layer;

[0030] The step of forming the high-impedance layer includes: sequentially forming at least one third high-impedance film layer, a first high-impedance film layer located on the side of the at least one third high-impedance film layer opposite to the anode layer, and at least one second high-impedance film layer located on the side of the first high-impedance film layer opposite to the anode layer; the resistivity of the first high-impedance film layer is greater than the resistivity of the second high-impedance film layer and the resistivity of the third high-impedance film layer; the resistivity of the first high-impedance film layer, the second high-impedance film layer and the third high-impedance film layer is greater than the resistivity of the cathode layer and the resistivity of the electron injection layer, respectively.

[0031] In one embodiment, each layer of the high-resistivity layer is formed using a sputtering process.

[0032] In one embodiment, in the sputtering process for preparing the first high-impedance film, oxygen accounts for a first proportion in the sputtering gas; in the sputtering process for preparing the second high-impedance film, oxygen accounts for a second proportion in the sputtering gas; and in the sputtering process for preparing the third high-impedance film, oxygen accounts for a third proportion in the sputtering gas; the first proportion is greater than both the second and third proportions; and / or,

[0033] The power density used in the sputtering process for preparing the first high-impedance film is the first power density, the power density used in the sputtering process for preparing the second high-impedance film is the second power density, and the power density used in the sputtering process for preparing the third high-impedance film is the third power density; the first power density is less than the second power density and the third power density, respectively.

[0034] According to a fourth aspect of the embodiments of this application, a display device is provided, the display device including the display substrate described above.

[0035] The display substrate, its fabrication method, and display device provided in this invention include a light-emitting device comprising at least one high-impedance layer. The resistivity of each layer of the high-impedance layer is higher than that of its adjacent layers. The high-impedance layer can modify the area around particles in the light-emitting device, increasing the resistance between the anode and cathode layers at locations where short circuits are likely to occur due to the presence of particles. This significantly improves the short-circuit problem caused by the presence of particles, effectively reduces the number of dark spots on the display substrate, and improves the product yield of the display substrate. The resistivity of at least one second high-impedance layer located between the first high-impedance layer and the cathode layer is lower than that of the first high-impedance layer, and the resistivity of at least one third high-impedance layer located between the first high-impedance layer and the electron injection layer is lower than that of the first high-impedance layer. This makes the work function change between the electron injection layer and the cathode layer smoother, reduces the difficulty of electron injection from the cathode layer to the electron injection layer, increases the electron transport rate, and improves the problems of high driving voltage and low optical performance of the light-emitting substrate caused by low electron transport rate. Attached Figure Description

[0036] Figure 1 This is a schematic diagram illustrating the principle of short-circuit problem in sub-pixels caused by the presence of particulate matter in an OLED display device.

[0037] Figure 2 This is a schematic diagram illustrating the principle of short-circuit problem in sub-pixels caused by the presence of particulate matter in another type of OLED display device.

[0038] Figure 3 This is a cross-sectional view of a display substrate provided in an exemplary embodiment of this application;

[0039] Figure 4 This is a cross-sectional view of a display substrate provided in another exemplary embodiment of this application;

[0040] Figure 5 This is a cross-sectional view of a display substrate provided in another exemplary embodiment of this application;

[0041] Figure 6 This is a schematic diagram of electron transport from the cathode layer to the electron injection layer in a display substrate provided by an exemplary embodiment of this application;

[0042] Figure 7 This is a partial structural schematic diagram of a display substrate provided in another exemplary embodiment of this application;

[0043] Figure 8 yes Figure 7 The image shows a partial cross-sectional view obtained by cutting the display substrate along line AA. Detailed Implementation

[0044] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0045] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0046] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0047] Figure 1 The diagram illustrates the principle of a sub-pixel short circuit problem caused by particulate matter in an OLED display device. This OLED display device includes a substrate 10', an anode layer 20', an organic light-emitting layer 30', and a cathode layer 40', wherein the organic light-emitting layer 30' is fabricated using a vapor deposition process. Figure 1 As shown, there is no organic light-emitting layer at the bottom corner of particle 21', or the organic light-emitting layer 30' and cathode layer 40' at the bottom corner of particle 21' are thin. During the operation of the OLED display device, when there is no organic light-emitting layer at the bottom corner of particle 21', the anode layer and cathode layer at that location will directly contact each other and short-circuit. When the thickness of the organic light-emitting layer 30' at the bottom corner of the particle is thin, during the operation of the OLED display device, the organic light-emitting layer 30' at the bottom corner of the particle will be burned, causing the cathode layer and anode layer at that location to contact each other and short-circuit. When the cathode layer and anode layer short-circuit, dark spots will appear on the display substrate.

[0048] Figure 2The diagram illustrates the principle of sub-pixel short-circuiting caused by particulate matter in another type of OLED display device. This OLED display device includes a substrate 10', an anode layer 20', an organic light-emitting layer 30', and a cathode layer 40', wherein the organic light-emitting layer 30' is fabricated using an inkjet printing process. Figure 1 As shown, the organic light-emitting layer 30' at the top of the particle 21' is relatively thin. During the operation of the OLED display device, the organic light-emitting layer 30' at the top of the particle 21' is easily burned out, causing a short circuit between the cathode layer and the anode layer at that location, resulting in a dark spot.

[0049] This application provides a display substrate, a method for fabricating the same, and a display device, which can solve the above-mentioned technical problems. The display substrate, its fabrication method, and the display device according to the embodiments of this application will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the features in the following embodiments can complement or combine with each other.

[0050] Example 1

[0051] This application provides a display substrate. For example... Figures 3 to 5 As shown, the display substrate includes a substrate 10 and sub-pixels located on the substrate 10, and the sub-pixels include light-emitting devices 20.

[0052] The light-emitting device 20 includes an anode layer 21, a hole injection layer 22, a hole transport layer 23, a light-emitting material layer 24, an electron transport layer 25, an electron injection layer 26, and a cathode layer 28, which are sequentially disposed thereon. The light-emitting device 20 includes at least one electron injection layer 26, and the light-emitting device 20 also includes at least one high-impedance layer 27, which is located between the electron injection layer 26 and the cathode layer 28.

[0053] The high-impedance layer 27 includes a first high-impedance film layer 271, at least one second high-impedance film layer 272 located between the first high-impedance film layer 271 and the cathode layer 28, and at least one third high-impedance film layer 273 located between the first high-impedance film layer 271 and the electron injection layer 26. The resistivity of the first high-impedance film layer 271 is greater than the resistivity of the second high-impedance film layer 272 and the resistivity of the third high-impedance film layer 273, respectively; the resistivity of the first high-impedance film layer 271, the second high-impedance film layer 272, and the third high-impedance film layer 273 is greater than the resistivity of the cathode layer 28 and the resistivity of the electron injection layer 26, respectively.

[0054] The display substrate provided in this application embodiment includes a light-emitting device 20 comprising at least one high-resistivity layer 27. The resistivity of each layer of the high-resistivity layer 27 is higher than that of its adjacent layers. That is, the resistivity of each layer of the high-resistivity layer 27 is higher than that of the electron injection layer 26 and the cathode layer 28. The high-resistivity layer 27 can modify the area around particles in the light-emitting device, increasing the resistance between the anode layer 21 and the cathode layer 28 at locations where short circuits are likely to occur due to the presence of particles. This greatly improves the short circuit problem caused by the presence of particles, effectively reduces the number of dark spots on the display substrate, and improves the product yield of the display substrate. The resistivity of at least one second high-resistivity layer 272 located between the first high-resistivity layer 271 and the cathode layer 28 in the high-resistivity layer 27 is lower than that of the first high-resistivity layer 271. The resistivity of at least one third high-resistivity layer 272 located between the first high-resistivity layer 271 and the electron injection layer 26 is lower than that of the first high-resistivity layer 271. Since the resistivity of 73 is less than that of the first high-impedance film layer, the work function difference between the cathode layer 28 and the second high-impedance film layer 272, and the work function difference between the first high-impedance film layer 271 and the second high-impedance film layer 272 are all less than the work function difference between the cathode layer 28 and the first high-impedance film layer 271. Similarly, the work function difference between the first high-impedance film layer 271 and the third high-impedance film layer 273, and the work function difference between the third high-impedance film layer 273 and the electron injection layer 26 are all less than the work function difference between the first high-impedance film layer 271 and the electron injection layer 26. This means that the work function change between the electron injection layer 26 and the cathode layer 28 is smoother, which reduces the difficulty of injecting electrons from the cathode layer 28 to the first high-impedance film layer 271 and from the first high-impedance film layer 271 to the electron injection layer 26, thereby increasing the electron transport rate and improving the problems of high driving voltage and low optical performance of the light-emitting substrate caused by low electron transport rate.

[0055] In one embodiment, such as Figure 3 and Figure 4 As shown, the display substrate includes an electron injection layer 26 and a high impedance layer 27, which is located between the electron injection layer 26 and the cathode layer 28.

[0056] In another embodiment, when the number of electron injection layers 26 and high impedance layers 27 is greater than or equal to two, the electron injection layers 26 and high impedance layers 27 are arranged alternately. This arrangement allows the high impedance layers 27 to better modify particles within the sub-pixel, thus helping to improve the problem of sub-pixel short circuits caused by the presence of particles within the sub-pixel. Furthermore, this arrangement allows for a smaller film thickness for each electron injection layer 26 and high impedance layer 27, resulting in a smoother change in work function between the electron injection layer 26 and the cathode layer 28, which is more conducive to electron injection and transport. Figure 5In the illustrated embodiment, the light-emitting device 20 of the display substrate includes two electron injection layers 26 and two high-impedance layers 27, each high-impedance layer 27 being located on the side of the electron injection layer 26 facing the cathode layer 28. In other embodiments, the light-emitting device 20 of the display substrate may include three or more electron injection layers 26 and high-impedance layers 27.

[0057] In one embodiment, the thickness of the first high-impedance film layer 271 is greater than the thickness of the second high-impedance film layer 272 and the thickness of the third high-impedance film layer 273. Since the resistivity of the first high-impedance film layer 271 is greater than that of the second high-impedance film layer 272 and the third high-impedance film layer 273, the greater the thickness of the first high-impedance film layer 271, the greater the resistance, and the better the improvement effect on the short-circuit problem of the sub-pixel. By setting the thickness of the first high-impedance film layer 271 to be greater than that of the second high-impedance film layer 272 and the third high-impedance film layer 273, the resistance at the location in the sub-pixel where short circuits are likely to occur can be effectively increased, and the number of dark spots generated by the display substrate can be effectively reduced.

[0058] In some embodiments, the thickness of the first high-impedance film layer 271 ranges from 50 nm to 200 nm, the thickness of the second high-impedance film layer 272 ranges from 5 nm to 10 nm, and the thickness of the third high-impedance film layer 273 ranges from 5 nm to 10 nm. This configuration effectively increases the resistance of the high-impedance layer 27 between the cathode and anode layers at locations prone to short circuits within the sub-pixel, and makes the work function change between the electron injection layer 26 and the cathode layer 28 smoother. Simultaneously, it avoids excessively increasing the thickness of the display substrate due to the high-impedance layer 27, which would hinder the achievement of a thinner display substrate. In some exemplary embodiments, the thickness of the first high-impedance film layer 271 is, for example, 50 nm, 100 nm, 150 nm, 200 nm, etc.; the thickness of the second high-impedance film layer 272 is, for example, 5 nm, 7 nm, 8 nm, 10 nm, etc.; and the thickness of the third high-impedance film layer 273 is, for example, 5 nm, 7 nm, 8 nm, 10 nm, etc.

[0059] In one embodiment, such as Figure 3 As shown, the high-impedance film layer includes a second high-impedance film layer 272 and a third high-impedance film layer 273.

[0060] In another embodiment, such as Figure 4As shown, the high-impedance layer 27 includes two or more second high-impedance film layers 272. Within the same high-impedance layer 27, the resistivity of the second high-impedance film layer 272 gradually increases in the direction from the cathode layer 28 to the first high-impedance film layer 271. This arrangement, with two or more second high-impedance film layers 272, allows for a smoother transition in the work function between the cathode layer 28 and the first high-impedance film layer 271, which helps to reduce the difficulty of electron injection and transport, and improves the electron transport rate. Figure 4 In the illustrated embodiment, the high-resistivity layer 27 comprises two second high-resistivity film layers 272. In other embodiments, the high-resistivity layer 27 may comprise three or more second high-resistivity film layers 272.

[0061] like Figure 4 As shown, the high-impedance layer 27 includes two or more third high-impedance film layers 273. Within the same high-impedance layer 27, the resistivity of the third high-impedance film layer 273 gradually decreases in the direction from the cathode layer 28 to the first high-impedance film layer 271. This configuration, with two or more second high-impedance film layers 272, makes the work function change between the first high-impedance film layer 271 and the electron injection layer 26 more gradual, which helps to reduce the difficulty of electron injection and transport, and improves the electron transport rate. Figure 4 In the illustrated embodiment, the high-resistivity layer 27 comprises two third high-resistivity film layers 273. In other embodiments, the high-resistivity layer 27 may comprise three or more third high-resistivity film layers 273.

[0062] In one embodiment, the first high-resistivity film layer 271, the second high-resistivity film layer 272, and the third high-resistivity film layer 273 are made of the same material. With this configuration, when the first high-resistivity film layer 271, the second high-resistivity film layer 272, and the third high-resistivity film layer 273 are fabricated using a sputtering process, they can be fabricated using the same target material, which helps reduce the fabrication cost of the display substrate and simplifies the fabrication process.

[0063] In one embodiment, the materials of the first high-resistivity film 271, the second high-resistivity film 272, and the third high-resistivity film 273 are selected from at least one of zinc oxide, titanium oxide, tin oxide, and indium oxide. For example, the materials of the first high-resistivity film 271, the second high-resistivity film 272, and the third high-resistivity film 273 may all be zinc oxide, prepared from the same zinc oxide target using a sputtering process.

[0064] In one embodiment, the resistivity of the first high-impedance film layer 271 is in the range of 10. 4 Ω*cm~106 The resistivity of the second high-resistivity film layer 272 and the third high-resistivity film layer 273 is in the range of 10 Ω*cm. 2 Ω*cm~10 3 Ω*cm. With this configuration, the high-impedance layer 27 can effectively increase the resistance between the anode layer 21 and the cathode layer 28 at locations where short circuits are likely to occur around particles within the sub-pixel, while also achieving a smooth transition of the work function between the electron injection layer 26 and the cathode layer 28.

[0065] In one embodiment, the absolute value of the work function of the cathode layer 28 is in the range of 3.6 eV to 4.2 eV, the absolute value of the work function of the first high-impedance film layer 271 is in the range of 5.2 eV to 6.0 eV, and the absolute value of the work function of the second high-impedance film layer 272 and the third high-impedance film layer 273 is in the range of 4.5 eV to 5.2 eV.

[0066] like Figure 6 As shown, the work function difference between the cathode layer 28 and the second high-impedance film layer 272 is small, making electron transport from the cathode layer 28 to the second high-impedance film layer 272 easier; the work function difference between the second high-impedance film layer 272 and the first high-impedance film layer 271 is small, making electron transport from the second high-impedance film layer 272 to the first high-impedance film layer 271 easier; the work function difference between the first high-impedance film layer 271 and the third high-impedance film layer 273 is small, making electron transport from the first high-impedance film layer 271 to the third high-impedance film layer 273 easier; and the work function difference between the third high-impedance film layer 273 and the electron injection layer 26 is small, making electron transport from the third high-impedance film layer 273 to the electron injection layer 26 easier. In other words, the work function change between the cathode layer 28 and the electron injection layer 26 is more gradual, which reduces the difficulty of electron injection and transport, reduces electron loss, and increases the electron transport rate.

[0067] In one embodiment, the anode layer 21 may be a transparent film layer, and the material of the anode layer 21 may be a transparent conductive material, such as ITO (indium tin oxide). Alternatively, the anode layer 21 may include a reflective film layer and a transparent film layer, wherein the reflective film layer is located on the side of the transparent film layer away from the cathode layer 28, and the material of the transparent film layer may be ITO, and the material of the reflective film layer may be Ag.

[0068] In one embodiment, the cathode layer 28 may be made of metal, for example, the cathode layer 28 may be an Ag film or an Ag / Mg film.

[0069] In one embodiment, the display substrate further includes a driving circuit layer located between the substrate 10 and the light-emitting device 20. The driving circuit layer includes a plurality of pixel circuits, and each pixel circuit corresponds one-to-one with a sub-pixel, with each pixel circuit driving its corresponding sub-pixel.

[0070] Figures 3 to 5 In the illustrated embodiment, the anode layer 21 of the light-emitting device 20 is located between the cathode layer 28 and the substrate 10. In other embodiments, the cathode layer 28 of the light-emitting device 20 may be located between the anode layer 21 and the substrate 10.

[0071] Example 2

[0072] Embodiment 2 of this application provides a display substrate. For example... Figure 7 and Figure 8 As shown, the display substrate includes a substrate 10, a pixel defining layer 30, and a plurality of sub-pixels 201 located on the substrate 10. The pixel defining layer 30 includes a plurality of first defining portions 31 extending along a first direction Y and second defining portions 32 extending along a second direction X, wherein the first direction Y and the second direction X intersect. The distance from the surface of the first defining portion 31 away from the substrate 10 to the substrate 10 is greater than the distance from the surface of the second defining portion 32 away from the substrate 10 to the substrate 10. The first defining portions 31 and the second defining portions 32 enclose and form a plurality of pixel openings 301 defining the light-emitting areas of the sub-pixels 201. The second defining portion 32 includes a plurality of sub-defining portions 321 arranged along the second direction X, wherein the sub-defining portions 321 are located between two adjacent first defining portions 31, and a plurality of sub-defining portions 321 may be provided between two adjacent first defining portions 31, wherein the plurality of sub-defining portions 321 are spaced apart in the first direction Y.

[0073] The sub-pixel 201 includes a light-emitting device 20, which comprises an anode layer 21, a hole injection layer 22, a hole transport layer 23, a light-emitting material layer 24, an electron transport layer 25, an electron injection layer 26, and a cathode layer 28 arranged sequentially. The hole injection layer 22, the hole transport layer 23, and the light-emitting material layer 24 of the sub-pixel 201 are located between two adjacent first limiting portions 31. That is, the surfaces of the hole injection layer 22, the hole transport layer 23, and the light-emitting material layer 24 facing away from the substrate 10 are all lower than the surfaces of the first limiting portions 31 facing away from the substrate. The hole injection layers 22 of multiple sub-pixels 201 located between two adjacent first limiting portions 31 are connected, the hole transport layers 23 of multiple sub-pixels 201 located between two adjacent first limiting portions 31 are connected, and the light-emitting material layers 24 of multiple sub-pixels 201 located between two adjacent first limiting portions 31 are connected.

[0074] like Figures 3 to 5As shown, the light-emitting device 20 includes at least one electron injection layer 26 and at least one high-resistivity layer 27 located between the electron injection layer 26 and the cathode layer 28. The high-resistivity layer 27 includes a first high-resistivity film layer 271, at least one second high-resistivity film layer 272 located between the first high-resistivity film layer 271 and the cathode layer 28, and at least one third high-resistivity film layer 273 located between the first high-resistivity film layer 271 and the electron injection layer 26. The resistivity of the first high-resistivity film layer 271 is greater than the resistivity of the second high-resistivity film layer 272 and the resistivity of the third high-resistivity film layer 273, respectively. The resistivity of the first high-resistivity film layer 271, the second high-resistivity film layer 272, and the third high-resistivity film layer 273 is greater than the resistivity of the cathode layer 28 and the resistivity of the electron injection layer 26, respectively.

[0075] The display substrate provided in this application embodiment includes a light-emitting device 20 comprising at least one high-resistivity layer 27. The resistivity of each layer of the high-resistivity layer 27 is higher than that of its adjacent layers. That is, the resistivity of each layer of the high-resistivity layer 27 is higher than that of the electron injection layer 26 and the cathode layer 28. The high-resistivity layer 27 can modify the area around particles within the sub-pixel, increasing the resistance between the anode layer 21 and the cathode layer 28 at locations where short circuits are likely to occur due to the presence of particles within the sub-pixel. This greatly improves the problem of sub-pixel short circuits caused by the presence of particles, effectively reducing the number of dark spots on the display substrate and improving the product yield of the display substrate. The resistivity of at least one second high-resistivity layer 272 located between the first high-resistivity layer 271 and the cathode layer 28 in the high-resistivity layer 27 is lower than that of the first high-resistivity layer 271. The resistivity of at least one third high-resistivity layer 272 located between the first high-resistivity layer 271 and the electron injection layer 26 is also lower than that of the first high-resistivity layer 271. Since the resistivity of layer 273 is less than that of the first high-impedance film layer, the work function differences between the cathode layer 28 and the second high-impedance film layer 272, and between the first high-impedance film layer 271 and the second high-impedance film layer 272, are all less than the work function difference between the cathode layer 28 and the first high-impedance film layer 271. Similarly, the work function differences between the first high-impedance film layer 271 and the third high-impedance film layer 273, and between the third high-impedance film layer 273 and the electron injection layer 26, are all less than the work function difference between the first high-impedance film layer 271 and the electron injection layer 26. This means that the work function change between the electron injection layer 26 and the cathode layer 28 is smoother, which reduces the difficulty of injecting electrons from the cathode layer 28 to the first high-impedance film layer 271 and from the first high-impedance film layer 271 to the electron injection layer 26. This improves the electron transport rate and alleviates the problems of high driving voltage and low optical performance of the light-emitting substrate caused by low electron transport rate.

[0076] In one embodiment, the first direction Y and the second direction X may be perpendicular to each other. For example, the first direction Y is a row direction, and the second direction X is a row direction.

[0077] In one embodiment, the display substrate includes at least three sub-pixels 201 with different light-emitting colors. The sub-pixels with at least three different light-emitting colors include, for example, a first color sub-pixel, a second color sub-pixel, and a third color sub-pixel. The first color, the second color, and the third color are three primary colors, such as red, green, and blue.

[0078] In one embodiment, the hole injection layer 22, hole transport layer 23, and light-emitting material layer 24 of the display substrate are formed using an inkjet printing process. The plurality of sub-pixels 201 located between two adjacent first defining portions 31 emit the same color. For example... Figure 6 As shown, the three adjacent columns of sub-pixels can be red sub-pixel R, green sub-pixel G, and blue sub-pixel B, respectively.

[0079] When the hole injection layer 22 is formed using inkjet printing, ink flows between two adjacent first limiting portions 31. During the ink flow, the ink crosses the second limiting portion 32 between adjacent sub-pixels 201, thereby connecting the hole injection layers 22 of multiple sub-pixels 201 between two adjacent first limiting portions 31. Similarly, when the hole transport layer 23 is formed using inkjet printing, the hole transport layers 23 of multiple sub-pixels 201 between two adjacent first limiting portions 31 are connected; when the light-emitting material layer 24 is formed using inkjet printing, the light-emitting material layers 24 of multiple sub-pixels 201 between two adjacent first limiting portions 31 are connected. In the second direction X, the hole injection layer 22, hole transport layer 23, and light-emitting material layer 24 of adjacent sub-pixels are separated by the first limiting portion 31.

[0080] In one embodiment, at least one of the hole injection layer 22, hole transport layer 23, and luminescent material layer 24 of the sub-pixels 201 with different emission colors has a different thickness. This allows the luminous efficacy of the sub-pixels 201 with different emission colors to be improved respectively.

[0081] In some embodiments, the thickness of the hole injection layer 22 of the red sub-pixel R is greater than the thickness of the hole injection layer 22 of the green sub-pixel G and the thickness of the hole injection layer 22 of the blue sub-pixel B. When the hole injection layer 22 is fabricated using an inkjet printing process, the hole injection layer 22 of the red sub-pixel R can be formed alone in a single inkjet printing process, and the hole injection layers 22 of the green sub-pixel G and the blue sub-pixel B can be formed in a single inkjet printing process if they have the same thickness and are made of the same material. In an exemplary embodiment, the thickness of the hole injection layer 22 of the red sub-pixel R is 12 nm, and the thicknesses of the hole injection layers 22 of the green sub-pixel G and the blue sub-pixel B can be 6 nm.

[0082] In some embodiments, the thickness of the hole transport layer 23 of the red sub-pixel R is greater than the thickness of the hole transport layer 23 of the green sub-pixel G, and the thickness of the hole transport layer 23 of the green sub-pixel G is greater than the thickness of the hole transport layer 23 of the blue sub-pixel B. When the hole transport layer 23 is fabricated using an inkjet printing process, the hole transport layer 23 of the red sub-pixel R, the hole transport layer 23 of the green sub-pixel G, and the hole transport layer 23 of the blue sub-pixel B are formed in different inkjet printing processes. In an exemplary embodiment, the thickness of the hole transport layer 23 of the red sub-pixel R is 21 nm, the thickness of the hole transport layer 23 of the green sub-pixel G is 16 nm, and the thickness of the hole transport layer 23 of the blue sub-pixel B can be 11 nm.

[0083] In some embodiments, the thickness of the luminescent material layer 24 of the red sub-pixel R is greater than the thickness of the luminescent material layer 24 of the green sub-pixel G, and the thickness of the luminescent material layer 24 of the green sub-pixel G is greater than the thickness of the luminescent material layer 24 of the blue sub-pixel B. When the luminescent material layer 24 is fabricated using an inkjet printing process, the luminescent material layers 24 of the red sub-pixel R, the green sub-pixel G, and the blue sub-pixel B are formed in different inkjet printing processes. In one exemplary embodiment, the thickness of the luminescent material layer 24 of the red sub-pixel R is 87 nm, the thickness of the luminescent material layer 24 of the green sub-pixel G is 63 nm, and the thickness of the luminescent material layer 24 of the blue sub-pixel B may be 55 nm.

[0084] In one embodiment, the electron transport layer 25, the electron injection layer 26, and the cathode layer 28 may be a common layer, that is, a film layer covering the entire surface. The electron transport layer 25 and the electron injection layer 26 may be formed by a vapor deposition process.

[0085] In one embodiment, the thickness of the first high-resistivity film layer 271 is greater than the thickness of the second high-resistivity film layer 272 and the thickness of the third high-resistivity film layer 273.

[0086] In some embodiments, the thickness of the first high-resistivity film 271 ranges from 50 nm to 200 nm, the thickness of the second high-resistivity film 272 ranges from 5 nm to 10 nm, and the thickness of the third high-resistivity film 273 ranges from 5 nm to 10 nm.

[0087] In one embodiment, when the high impedance layer 27 includes two or more layers of the second high impedance film layer 272, the resistivity of the second high impedance film layer 272 gradually increases in the direction from the cathode layer 28 to the first high impedance film layer 271 within the same high impedance layer 27.

[0088] In one embodiment, when the high impedance layer 27 includes two or more third high impedance film layers 273, the resistivity of the third high impedance film layer 273 gradually decreases in the direction from the cathode layer 28 to the first high impedance film layer 271 within the same high impedance layer 27.

[0089] In one embodiment, the first high-resistivity film layer 271, the second high-resistivity film layer 272, and the third high-resistivity film layer 273 are made of the same material.

[0090] In one embodiment, when the number of cathode layer 28 and high impedance layer 27 is greater than or equal to two, the cathode layer 28 and high impedance layer 27 are arranged alternately.

[0091] In one embodiment, the resistivity of the first high-impedance film layer 271 is in the range of 10. 4 Ω*cm~10 6 The resistivity of the second high-resistivity film layer 272 and the third high-resistivity film layer 273 is in the range of 10 Ω*cm. 2 Ω*cm~10 3 Ω*cm.

[0092] In one embodiment, the absolute value of the work function of the cathode layer 28 is in the range of 3.6 eV to 4.2 eV, the absolute value of the work function of the first high-impedance film layer 271 is in the range of 5.2 eV to 6.0 eV, and the absolute value of the work function of the second high-impedance film layer 272 and the third high-impedance film layer 273 is in the range of 4.5 eV to 5.2 eV.

[0093] The display substrate provided in Embodiment 2 of this application and the display substrate provided in Embodiment 1 of this application belong to the same inventive concept. The relevant details and beneficial effects can be referred to each other and will not be repeated here.

[0094] Example 3

[0095] Embodiment 3 of this application provides a method for fabricating a display substrate. The method for fabricating the display substrate includes the following steps:

[0096] First, a substrate is provided.

[0097] Subsequently, a light-emitting device is formed on the substrate.

[0098] The step of forming a light-emitting device on the substrate includes: sequentially forming an anode layer, a hole injection layer, a hole transport layer, a light-emitting material layer, an electron transport layer, an electron injection layer, a high impedance layer, and a cathode layer; the light-emitting device includes at least one electron injection layer and at least one high impedance layer, wherein the high impedance layer is located between the electron injection layer and the cathode layer.

[0099] The step of forming the high-impedance layer includes: sequentially forming at least one third high-impedance film layer, a first high-impedance film layer located on the side of the at least one third high-impedance film layer opposite to the anode layer, and at least one second high-impedance film layer located on the side of the first high-impedance film layer opposite to the anode layer; the resistivity of the first high-impedance film layer is greater than the resistivity of the second high-impedance film layer and the resistivity of the third high-impedance film layer; the resistivity of the first high-impedance film layer, the second high-impedance film layer and the third high-impedance film layer is greater than the resistivity of the cathode layer and the resistivity of the electron injection layer, respectively.

[0100] In one embodiment, after forming the anode layer, the step of forming the light-emitting device located on the substrate further includes: forming a pixel defining layer. For example... Figure 7 As shown, the step of forming the pixel defining layer includes: forming a plurality of first defining portions 31 extending along a first direction Y and second defining portions 32 extending along a second direction X, wherein the first direction Y intersects the second direction X. The order in which the first defining portions 31 and the second defining portions 32 are formed is not limited; the first defining portions 31 may be formed first, followed by the second defining portions 32; or the second defining portions 32 may be formed first, followed by the first defining portions 31.

[0101] The distance from the surface of the first limiting portion 31 away from the substrate 10 to the substrate 10 is greater than the distance from the surface of the second limiting portion 32 away from the substrate 10 to the substrate 10. The first limiting portion 31 and the second limiting portion 32 enclose and form a plurality of pixel openings 301 defining the light-emitting area of ​​the sub-pixel 201. The second limiting portion 32 includes a plurality of sub-limiting portions 321 arranged along the second direction X, and the sub-limiting portions 321 are located between two adjacent first limiting portions 31.

[0102] In one embodiment, the light-emitting device includes at least three sub-pixels of different colors. For example, the light-emitting device includes sub-pixels of a first color, a second color, and a third color. The first color can be red, the second color can be green, and the third color can be blue. Multiple sub-pixels located between two adjacent first defining portions 31 and spaced apart along the first direction Y have the same color.

[0103] In one embodiment, the hole transport layer, the hole injection layer, and the light-emitting material layer can be formed using an inkjet printing process; the electron transport layer and the electron injection layer can be formed using a vapor deposition process.

[0104] In one embodiment, the hole injection layer can be fabricated as follows:

[0105] The hole injection layers of the first, second, and third color sub-pixels are printed sequentially using inkjet printing. These layers can be printed using the same or different inks. After inkjet printing, each color sub-pixel's hole injection layer undergoes vacuum drying and baking.

[0106] In one embodiment, the hole injection layers of the first, second, and third color sub-pixels can use the same ink, or different inks can be selected based on structural differences, with the same subsequent processing conditions (e.g., baking temperature) for each ink. After all three color sub-pixel hole injection layers have been inkjet printed, they can be uniformly vacuum dried using a VCD, followed by baking. The inkjet printing order of the three color sub-pixels' hole injection layers can be changed without strict limitations.

[0107] In one embodiment, when different inks are used for the hole injection layers of the first color sub-pixel, the second color sub-pixel, and the third color sub-pixel, depending on structural differences, and when the subsequent processing conditions (e.g., baking temperature) for using different inks are different, the specific manufacturing process can also be as follows:

[0108] The hole injection layer of the first color sub-pixel is printed using inkjet printing, and the hole injection layer of the first color sub-pixel is vacuum dried and baked at a first temperature.

[0109] The hole injection layer of the second color sub-pixel is printed using inkjet printing, and the hole injection layer of the second color sub-pixel is vacuum dried and baked at a second temperature.

[0110] The hole injection layer of the third color sub-pixel is printed using inkjet printing, and the hole injection layer of the second color sub-pixel is vacuum dried and baked at the third temperature.

[0111] The first, second, and third temperatures can all be different. For example, the first temperature is higher than the second temperature, and the second temperature is higher than the third temperature. That is to say, the hole injection layers of different color sub-pixels can be printed according to the baking temperature of the ink. First, the hole injection layer of the first color sub-pixel with the highest baking temperature is printed. After printing, VCD vacuum treatment and high-temperature baking are performed. Then, the hole injection layer of the second color sub-pixel with the next highest baking temperature is printed and VCD vacuum treatment and baking are performed. Finally, the hole injection layer of the third color sub-pixel with the lowest baking temperature is printed and VCD vacuum treatment and baking are performed accordingly.

[0112] In one embodiment, the fabrication process of the hole transport layer can be as follows:

[0113] The hole transport layer of the first color subpixel, the hole transport layer of the second color subpixel, and the hole transport layer of the third color subpixel are printed sequentially using inkjet printing. The hole transport layers of the first color subpixel, the second color subpixel, and the third color subpixel are printed using the same ink or different inks. The hole transport layers of the first color subpixel, the second color subpixel, and the third color subpixel are then subjected to vacuum drying and baking treatment after inkjet printing.

[0114] In the above scheme, the hole transport layers of the first, second, and third color sub-pixels can use the same ink, or different inks can be selected based on structural differences, with the same subsequent processing conditions (e.g., baking temperature) for each ink. After all three color sub-pixels' hole transport layers have been inkjet printed, they can be uniformly vacuum dried using a VCD, followed by baking. The inkjet printing order of the three color sub-pixels' hole transport layers can be changed without strict limitations.

[0115] In one embodiment, when the hole transport layers of the first color sub-pixel, the second color sub-pixel, and the third color sub-pixel use different inks due to structural differences, and when the subsequent processing conditions (e.g., baking temperature) for using different inks are different, the specific manufacturing process can also be as follows:

[0116] The hole transport layer of the first color sub-pixel is printed using inkjet printing, and the hole transport layer of the first color sub-pixel is vacuum dried and baked at a fourth temperature.

[0117] The hole transport layer of the second color sub-pixel is printed using inkjet printing, and the hole transport layer of the second color sub-pixel is vacuum dried and baked at the fifth temperature.

[0118] The hole transport layer of the third color subpixel is printed using inkjet printing, and then the hole transport layer of the third color subpixel is vacuum dried and baked at a temperature of the sixth temperature.

[0119] The fourth, fifth, and sixth temperatures can all be different. For example, the fourth temperature is higher than the fifth temperature, and the fifth temperature is higher than the sixth temperature. That is to say, the hole transport layers of the first, second, and third color sub-pixels can be printed according to the baking temperature of the ink. First, the hole transport layer of the first color sub-pixel with the highest baking temperature is printed, and after printing, VCD vacuum processing and high-temperature baking are performed. Then, the hole transport layer of the second color sub-pixel with the next highest baking temperature is printed, and VCD vacuum processing and baking are performed. Finally, the hole transport layer of the third color sub-pixel with the lowest baking temperature is printed, and corresponding VCD vacuum processing and baking are performed.

[0120] In one embodiment, the hole transport layer is a p-type organic semiconductor material. Specifically, the material can be an ink formulated from aromatic amine compounds, including one or a blend of the following materials and materials obtained by modifying and optimizing the substituents of the following materials:

[0121]

[0122] In one embodiment, the fabrication process of the luminescent material layer can be as follows:

[0123] The luminescent material layers of the first, second, and third color sub-pixels are printed sequentially using inkjet printing. The luminescent material layers of the first, second, and third color sub-pixels are printed using the same or different inks. After inkjet printing, the luminescent material layers of the first, second, and third color sub-pixels are vacuum dried and baked.

[0124] In the above scheme, the luminescent material layers of the first, second, and third color sub-pixels can use the same ink, or different inks can be selected based on structural differences, with the same subsequent processing conditions (e.g., baking temperature) for each ink. After all three color sub-pixel luminescent material layers have been inkjet printed, they can be uniformly vacuum dried using a VCD, followed by baking. The inkjet printing order of the three color sub-pixel luminescent material layers can be changed without strict limitations.

[0125] It is understandable that, based on structural differences, when different inks are used for the luminescent material layers of the first color sub-pixel, the second color sub-pixel, and the third color sub-pixel, and when the subsequent processing conditions (e.g., baking temperature) of the different inks used are different, the specific manufacturing process can also be as follows:

[0126] The luminescent material layer of the first color sub-pixel is printed using inkjet printing, and the luminescent material layer of the first color sub-pixel is then vacuum dried and baked at a temperature of the seventh temperature.

[0127] The luminescent material layer of the second color sub-pixel is printed using inkjet printing, and then the luminescent material layer of the second color sub-pixel is vacuum dried and baked at an eighth temperature.

[0128] The luminescent material layer of the third color sub-pixel is printed using inkjet printing, and then the luminescent material layer of the third color sub-pixel is vacuum dried and baked at the ninth temperature.

[0129] The seventh, eighth, and ninth temperatures can all be different. For example, the seventh temperature is higher than the eighth temperature, and the eighth temperature is higher than the ninth temperature. That is to say, the luminescent material layers of the first, second, and third color sub-pixels can be printed according to the baking temperature of the ink. First, the luminescent material layer of the first color sub-pixel with a high baking temperature is printed, and after printing, VCD vacuum treatment and high-temperature baking are performed. Then, the luminescent material layer of the second color sub-pixel with a slightly higher baking temperature is printed, and VCD vacuum treatment and baking are performed. Finally, the luminescent material layer of the third color sub-pixel with the lowest baking temperature is printed, and corresponding VCD vacuum treatment and baking are performed.

[0130] In one embodiment, the electron transport layer and the electron injection layer are a common layer, which can be formed by vapor deposition. The electron injection layer is an n-type organic semiconductor material, and the specific material can be one or a blend of two of the following materials and materials obtained by modifying and optimizing the following material substituents:

[0131]

[0132]

[0133] In one embodiment, the cathode layer can be formed by vapor deposition, and a metal thin film, such as Ag or Ag / Mg film, can be selected. In another embodiment, the cathode layer can be formed by sputtering, and a low-resistance transparent conductive oxide thin film, such as IZO (indium zinc oxide) or In2O3 (indium oxide), can be selected.

[0134] In one embodiment, each layer of the high-resistivity layer 27 is formed using a sputtering process. The high-resistivity layer 27 formed by sputtering has a better coating effect on particles within the sub-pixel, which helps to prevent short circuits between the anode layer 21 and the cathode layer 28 of the sub-pixel and reduces the number of dark spots on the display substrate.

[0135] In one embodiment, the sputtering gas used in the sputtering process is oxygen and argon, and the proportion of oxygen in the sputtering gas is less than or equal to 10%.

[0136] In one embodiment, in the sputtering process for preparing the first high-impedance film, oxygen accounts for a first proportion in the sputtering gas; in the sputtering process for preparing the second high-impedance film, oxygen accounts for a second proportion in the sputtering gas; and in the sputtering process for preparing the third high-impedance film, oxygen accounts for a third proportion in the sputtering gas. The first proportion is greater than the second proportion and the third proportion, respectively. This configuration ensures that the resistivity of the first high-impedance film is greater than the resistivity of both the second and third high-impedance films.

[0137] In one embodiment, the power density used in the sputtering process for preparing the first high-impedance film is a first power density, the power density used in the sputtering process for preparing the second high-impedance film is a second power density, and the power density used in the sputtering process for preparing the third high-impedance film is a third power density; the first power density is less than the second power density and the third power density, respectively. This configuration ensures that the resistivity of the first high-impedance film is greater than the resistivity of both the second and third high-impedance films.

[0138] In one embodiment, the materials of the first high-resistivity film layer 271, the second high-resistivity film layer 272, and the third high-resistivity film layer 273 are selected from at least one of zinc oxide, titanium oxide, tin oxide, and indium oxide.

[0139] When zinc oxide and titanium oxide are used as materials for high-resistivity films, different high-resistivity films are obtained by changing the film formation conditions in the sputtering process. The test results of different high-resistivity films are shown in Table 1.

[0140] Table 1

[0141]

[0142] In Table 1, the gas type refers to the proportion of oxygen in the sputtering gas, which is a mixture of oxygen and argon. As shown in Table 1, when the material of the high-resistivity film is the same, the resistivity and work function of the resulting high-resistivity film can be changed by altering the proportion of oxygen and the power density in the sputtering gas.

[0143] In one embodiment, the first high-impedance film layer, the second high-impedance film layer, and the third high-impedance film layer in the high-impedance layer are prepared using the same target material. This arrangement eliminates the need to change the target material during the preparation of the high-impedance layer, simplifying the preparation process and reducing costs. The method for preparing the display substrate provided in Embodiment 3 of this application belongs to the same inventive concept as the display substrates provided in the above two embodiments; related details and descriptions of beneficial effects can be found interchangeably.

[0144] This application also provides a display device, which includes the display substrate described above.

[0145] In one embodiment, the display device further includes a cover plate located on the side of the display substrate facing away from the substrate.

[0146] In one embodiment, the display device may further include a housing in which a display substrate is embedded.

[0147] The display device in this embodiment can be any product or component with display function, such as electronic paper, mobile phone, tablet computer, television, laptop computer, digital photo frame, or vehicle display device.

[0148] It should be noted that the dimensions of layers and regions may be exaggerated in the accompanying drawings for clarity. Furthermore, it is understood that when an element or layer is referred to as being "on" another element or layer, it can be directly on the other element, or there may be intermediate layers. Additionally, it is understood that when an element or layer is referred to as being "below" another element or layer, it can be directly below the other element, or there may be more than one intermediate layer or element. Furthermore, it is also understood that when a layer or element is referred to as being "between" two layers or two elements, it can be the only layer between the two layers or two elements, or there may be more than one intermediate layer or element. Similar reference numerals throughout indicate similar elements.

[0149] In this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0150] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. The invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0151] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A display substrate, characterized in that, The display substrate includes a substrate and sub-pixels located on the substrate, and the sub-pixels include light-emitting devices; The light-emitting device includes an anode layer, a light-emitting material layer, an electron transport layer, an electron injection layer, and a cathode layer arranged sequentially; the light-emitting device includes at least one electron injection layer, and the light-emitting device further includes at least one high-impedance layer, the high-impedance layer being located between the electron injection layer and the cathode layer; The high-impedance layer includes a first high-impedance film layer, at least one second high-impedance film layer located between the first high-impedance film layer and the cathode layer, and at least one third high-impedance film layer located between the first high-impedance film layer and the electron injection layer; the resistivity of the first high-impedance film layer is greater than the resistivity of the second high-impedance film layer and the resistivity of the third high-impedance film layer; the resistivity of the first high-impedance film layer, the second high-impedance film layer, and the third high-impedance film layer is greater than the resistivity of the cathode layer and the resistivity of the electron injection layer; The high impedance layer includes two or more second high impedance film layers. In the same high impedance layer, the resistivity of the second high impedance film layer gradually increases in the direction from the cathode layer to the first high impedance film layer. The high impedance layer includes two or more third high impedance film layers. In the same high impedance layer, the resistivity of the third high impedance film layer gradually decreases in the direction from the cathode layer to the first high impedance film layer.

2. The display substrate according to claim 1, characterized in that, The thickness of the first high-impedance film layer is greater than the thickness of the second high-impedance film layer and the thickness of the third high-impedance film layer.

3. The display substrate according to claim 2, characterized in that, The thickness of the first high-resistivity film layer ranges from 50 nm to 200 nm, the thickness of the second high-resistivity film layer ranges from 5 nm to 10 nm, and the thickness of the third high-resistivity film layer ranges from 5 nm to 10 nm.

4. The display substrate according to claim 1, characterized in that, The first high-impedance film layer, the second high-impedance film layer, and the third high-impedance film layer are made of the same material.

5. The display substrate according to claim 1, characterized in that, The materials of the first high-resistivity film layer, the second high-resistivity film layer, and the third high-resistivity film layer are selected from at least one of zinc oxide, titanium oxide, tin oxide, and indium oxide.

6. The display substrate according to claim 1, characterized in that, When the number of electron injection layers and high impedance layers is greater than or equal to two, the electron injection layers and high impedance layers are arranged alternately.

7. The display substrate according to claim 1, characterized in that, The resistivity range of the first high-impedance film layer is: The resistivity ranges of the second high-resistivity film layer and the third high-resistivity film layer are as follows: .

8. The display substrate according to claim 1, characterized in that, The absolute value of the work function of the cathode layer ranges from 3.6 eV to 4.2 eV, the absolute value of the work function of the first high-impedance film layer ranges from 5.2 eV to 6.0 eV, and the absolute value of the work function of the second high-impedance film layer and the third high-impedance film layer ranges from 4.5 eV to 5.2 eV.

9. A display substrate, characterized in that, The display substrate includes a substrate and a pixel defining layer and a plurality of sub-pixels located on the substrate; The pixel defining layer includes a plurality of first defining portions extending along a first direction and second defining portions extending along a second direction, wherein the first direction intersects the second direction; The distance from the surface of the first limiting portion away from the substrate to the substrate is greater than the distance from the surface of the second limiting portion away from the substrate to the substrate; the first limiting portion and the second limiting portion together form a plurality of pixel openings defining the light-emitting areas of the sub-pixels; The sub-pixel includes a light-emitting device, which includes an anode layer, a hole injection layer, a hole transport layer, a light-emitting material layer, an electron transport layer, an electron injection layer, and a cathode layer arranged sequentially. The hole injection layer, hole transport layer, and light-emitting material layer of the sub-pixel are located between two adjacent first limiting portions, and the hole injection layers of multiple sub-pixels located between two adjacent first limiting portions are connected, the hole transport layers of multiple sub-pixels located between two adjacent first limiting portions are connected, and the light-emitting material layers of multiple sub-pixels located between two adjacent first limiting portions are connected. The light-emitting device includes at least one electron injection layer and at least one high-resistivity layer located between the electron injection layer and the cathode layer. The high-resistivity layer includes a first high-resistivity film, at least one second high-resistivity film located between the first high-resistivity film and the cathode layer, and at least one third high-resistivity film located between the first high-resistivity film and the electron injection layer. The resistivity of the first high-resistivity film is greater than the resistivity of the second high-resistivity film and the resistivity of the third high-resistivity film. The resistivity of the first high-resistivity film, the second high-resistivity film, and the third high-resistivity film are all greater than the resistivity of the cathode layer and the resistivity of the electron injection layer. The high impedance layer includes two or more second high impedance film layers. In the same high impedance layer, the resistivity of the second high impedance film layer gradually increases in the direction from the cathode layer to the first high impedance film layer. The high-impedance layer includes two or more third high-impedance film layers. In the same high-impedance layer, the resistivity of the third high-impedance film layer gradually decreases in the direction from the cathode layer to the first high-impedance film layer.

10. The display substrate according to claim 9, characterized in that, The thickness of the first high-impedance film layer is greater than the thickness of the second high-impedance film layer and the thickness of the third high-impedance film layer.

11. The display substrate according to claim 9, characterized in that, The first high-impedance film layer, the second high-impedance film layer, and the third high-impedance film layer are made of the same material.

12. The display substrate according to claim 9, characterized in that, When the number of electron injection layers and high impedance layers is greater than or equal to two, the electron injection layers and high impedance layers are arranged alternately.

13. A method for preparing a display substrate, characterized in that, The method for preparing the display substrate includes: Provide substrate; Forming a light-emitting device located on the substrate; The method of forming a light-emitting device on the substrate includes: sequentially forming an anode layer, a light-emitting material layer, an electron transport layer, an electron injection layer, a high-impedance layer, and a cathode layer; the light-emitting device includes at least one electron injection layer and at least one high-impedance layer, wherein the high-impedance layer is located between the electron injection layer and the cathode layer; The step of forming the high-resistivity layer includes: sequentially forming at least one third high-resistivity film layer, a first high-resistivity film layer located on the side of the at least one third high-resistivity film layer opposite to the anode layer, and at least one second high-resistivity film layer located on the side of the first high-resistivity film layer opposite to the anode layer; the resistivity of the first high-resistivity film layer is greater than the resistivity of the second high-resistivity film layer and the resistivity of the third high-resistivity film layer; the resistivity of the first high-resistivity film layer, the second high-resistivity film layer, and the third high-resistivity film layer are all greater than the resistivity of the cathode layer and the resistivity of the electron injection layer; The high impedance layer includes two or more second high impedance film layers. In the same high impedance layer, the resistivity of the second high impedance film layer gradually increases in the direction from the cathode layer to the first high impedance film layer. The high-impedance layer includes two or more third high-impedance film layers. In the same high-impedance layer, the resistivity of the third high-impedance film layer gradually decreases in the direction from the cathode layer to the first high-impedance film layer.

14. The method for preparing a display substrate according to claim 13, characterized in that, Each layer of the high-resistivity layer is formed using a sputtering process.

15. The method for preparing a display substrate according to claim 14, characterized in that, In the sputtering process for preparing the first high-impedance film, oxygen accounts for a first proportion in the sputtering gas; in the sputtering process for preparing the second high-impedance film, oxygen accounts for a second proportion in the sputtering gas; in the sputtering process for preparing the third high-impedance film, oxygen accounts for a third proportion in the sputtering gas; the first proportion is greater than both the second and third proportions; and / or, The power density used in the sputtering process for preparing the first high-impedance film is the first power density, the power density used in the sputtering process for preparing the second high-impedance film is the second power density, and the power density used in the sputtering process for preparing the third high-impedance film is the third power density; the first power density is less than the second power density and the third power density, respectively.

16. A display device, characterized in that, The display device includes the display substrate according to any one of claims 1 to 12.

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