Light-emitting substrate, preparation method thereof and display device

Abstract

The invention provides a light-emitting substrate and a preparation method thereof, and a display device, the light-emitting substrate comprises a first electrode layer and a second electrode layer which are oppositely arranged, and a light-emitting layer and an electron transport layer which are located between the first electrode layer and the second electrode layer, the light-emitting layer comprises a first light-emitting unit and a second light-emitting unit, the electron transmission layer comprises a first electron transmission unit located between the first light-emitting unit and the second electrode layer and a multiplexing unit located on the adjacent side of the first electron transmission unit, and the multiplexing unit is multiplexed into the second light-emitting unit, so that the performance of the OLED device is improved, and meanwhile, the structure of the OLED device is simplified.

Description

Technical Field

[0001] This application relates to the field of display technologies, and particularly to a light-emitting substrate, a preparation method thereof, and a display device. Background Art

[0002] Quantum-dot Light Emitting Diode (QLED) is a display technology based on quantum dot technology. Quantum dot materials can adjust the wavelength of the emitted light according to their size, thereby achieving more precise color control and wider color gamut coverage. QLED technology also has other advantages, such as longer lifespan, lower energy consumption, and faster response time. It can also achieve thinner and lighter display designs, as well as wider viewing angles. Through the application of quantum dots, it can provide more excellent image quality and richer color performance.

[0003] The Hole Blocking Layer (HBL) is a commonly used functional layer in electroluminescent devices such as Organic Light Emitting Diodes (OLEDs). Its main function is to prevent the diffusion and leakage of holes in the OLED device, thereby maintaining the balance of charges, which helps to improve the efficiency and stability of the organic light emitting diode. In addition, the organic light emitting diode device also includes multiple organic functional layers located between the light-emitting layer and the electrode layer, such as an electron transport layer, a hole transport layer, etc., resulting in a relatively complex structure of the OLED device. Summary of the Invention

[0004] This application provides a light-emitting substrate and a preparation method thereof to simplify the structure of the OLED device while improving its performance.

[0005] To solve the above problems, the technical solutions provided in this application are as follows:

[0006] An embodiment of this application provides a light-emitting substrate, which includes:

[0007] A first electrode layer;

[0008] A second electrode layer, disposed opposite to the first electrode layer;

[0009] A light-emitting layer, located between the first electrode layer and the second electrode layer, and the light-emitting layer includes a first light-emitting unit and a second light-emitting unit; and

[0010] An electron transport layer, including a first electron transport unit located between the first light-emitting unit and the second electrode layer;

[0011] Wherein, the electron transport layer further includes a multiplexing unit, and the multiplexing unit is multiplexed as the second light-emitting unit.

[0012] In the light-emitting substrate provided by the embodiments of the present application, the material of the electron transport layer includes a blue quantum dot electroluminescent material.

[0013] In the light-emitting substrate provided by the embodiments of the present application, the blue quantum dot electroluminescent material is an n-type semiconductor material, and the bandgap range of the blue quantum dot electroluminescent material is 2.6 eV to 3.0 eV.

[0014] In the light-emitting substrate provided by the embodiments of the present application, the light-emitting substrate further includes a hole blocking layer, the electron transport layer is multiplexed as the hole blocking layer, and the thickness range of the electron transport layer is 10 nanometers to 20 nanometers.

[0015] In the light-emitting substrate provided by the embodiments of the present application, the light-emitting layer further includes a third light-emitting unit, and the electron transport layer further includes a second electron transport unit located between the third light-emitting unit and the second electrode layer, and the second electron transport unit connects the first electron transport unit and the multiplexing unit;

[0016] Wherein, one of the first light-emitting unit and the third light-emitting unit is used to emit red light, the other is used to emit green light, and the second light-emitting unit is used to emit blue light.

[0017] In the light-emitting substrate provided by the embodiments of the present application, the light-emitting substrate further includes a hole transport layer, and the hole transport layer is located between the light-emitting layer and the first electrode layer;

[0018] Wherein, the hole transport layer includes a first hole transport unit, a second hole transport unit, and a third hole transport unit. The first hole transport unit is located between the first light-emitting unit and the first electrode layer, the second hole transport unit is located between the third light-emitting unit and the first electrode layer, and the third hole transport unit is located between the multiplexing unit and the first electrode layer.

[0019] In the light-emitting substrate provided by the embodiments of the present application, the material of the first light-emitting unit includes a red organic light-emitting material, and the material of the third light-emitting unit includes a green organic light-emitting material.

[0020] The embodiments of the present application further provide a method for manufacturing a light-emitting substrate, which includes:

[0021] Manufacture a first electrode layer;

[0022] Form a first light-emitting unit on the first electrode layer as a part of the light-emitting layer;

[0023] Prepare an electron transport layer, where the electron transport layer includes a first electron transport unit formed on the first light-emitting unit and a multiplexing unit formed on an adjacent side of the first electron transport unit, and the multiplexing unit is multiplexed as a second light-emitting unit of the light-emitting layer;

[0024] Form a second electrode layer on the electron transport layer.

[0025] In the method for preparing a light-emitting substrate provided in the embodiments of the present application, the step of preparing the electron transport layer includes:

[0026] Dope a blue quantum dot electroluminescent material in n-octane solvent to form printing ink;

[0027] Use inkjet printing to print the printing ink on the first light-emitting unit and the adjacent side of the first light-emitting unit;

[0028] Vacuum-dry the printing ink printed on the first light-emitting unit and the adjacent side of the first light-emitting unit to form the first electron transport unit and the multiplexing unit.

[0029] The embodiments of the present application also provide a display device, which includes the light-emitting substrate described in any one of the foregoing embodiments or the light-emitting substrate prepared by the method for preparing a light-emitting substrate described in any one of the foregoing embodiments.

[0030] The beneficial effects of the present application are as follows: In the light-emitting substrate, the method for preparing the same, and the display device provided by the present application, the light-emitting substrate includes a first electrode layer and a second electrode layer disposed opposite to each other, and a light-emitting layer and an electron transport layer located between the first electrode layer and the second electrode layer. The light-emitting layer includes a first light-emitting unit and a second light-emitting unit. The electron transport layer includes a first electron transport unit located between the first light-emitting unit and the second electrode layer, and a multiplexing unit located on an adjacent side of the first electron transport unit. The multiplexing unit is multiplexed as the second light-emitting unit, so as to improve the performance of the OLED device while simplifying the structure of the OLED device. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 It is a partial cross-sectional structure schematic diagram of the light-emitting substrate provided by the embodiments of the present application.

[0033] Figure 2Schematic flowchart of the method for preparing a light-emitting substrate provided in an embodiment of the present application.

[0034] Reference numerals:

[0035] 100, light-emitting substrate;

[0036] 10, first electrode layer; 11, first sub-electrode; 12, second sub-electrode; 13, third sub-electrode;

[0037] 20, second electrode layer;

[0038] 30, light-emitting layer; 31, first light-emitting unit; 32, third light-emitting unit; 33, second light-emitting unit;

[0039] 40, electron transport layer; 41, first electron transport unit; 42, multiplexing unit; 43, second electron transport unit;

[0040] 50, hole transport layer; 51, first hole transport unit; 52, second hole transport unit; 53, third hole transport unit. Detailed implementation manners

[0041] The descriptions of the following embodiments refer to the attached drawings, which are used to illustrate specific embodiments in which the present application can be implemented. The directional terms mentioned in the present application, such as [up], [down], [front], [back], [left], [right], [inside], [outside], [side], etc., only refer to the directions in the attached drawings. Therefore, the directional terms used are for explaining and understanding the present application, rather than for limiting the present application. In the drawings, units with similar structures are denoted by the same reference numerals. In the drawings, for the sake of clear understanding and easy description, the thicknesses of some layers and regions are exaggerated. That is, the dimensions and thicknesses of each component shown in the drawings are arbitrarily shown, but the present application is not limited thereto.

[0042] Referring to Figure 1 , Figure 1 , which is a partial cross-sectional structural schematic diagram of the light-emitting substrate provided in an embodiment of the present application. The light-emitting substrate 100 includes a first electrode layer 10 and a second electrode layer 20 arranged opposite to each other, and a light-emitting layer 30 and an electron transport layer 40 located between the first electrode layer 10 and the second electrode layer 20. The light-emitting layer 30 includes a first light-emitting unit 31 and a second light-emitting unit 33. The electron transport layer 40 includes a first electron transport unit 41 located between the first light-emitting unit 31 and the second electrode layer 20, and a multiplexing unit 42 located on the adjacent side of the first electron transport unit 41. The multiplexing unit 42 is multiplexed as the second light-emitting unit 33 to simplify the structure of the OLED device while improving the performance of the OLED device.

[0043] Specifically, the light-emitting substrate 100 further includes a substrate and a driving circuit layer disposed on the substrate. The first electrode layer 10 is located on the side of the driving circuit layer away from the substrate. The driving circuit layer includes a plurality of thin-film transistors. The first electrode layer 10 includes a plurality of sub-electrodes disposed at intervals, and the plurality of sub-electrodes include a first sub-electrode 11, a second sub-electrode 12, and a third sub-electrode 13. The first sub-electrode 11, the second sub-electrode 12, and the third sub-electrode 13 are respectively electrically connected to corresponding thin-film transistors. The first electrode layer 10 generally serves as an anode, and the material can be a transparent conductive material such as indium tin oxide (ITO) or zinc oxide (ZnO).

[0044] The second electrode layer 20 is disposed opposite to the first electrode layer 10 and is located on the side of the second electrode layer 20 away from the substrate. The second electrode layer 20 generally serves as a cathode, and the material can be a metal material such as aluminum (Al) or silver (Ag). Among them, the first electrode layer 10 is a patterned design, including a plurality of patterned sub-electrodes; the second electrode layer 20 is a planar electrode, which is a whole-surface design.

[0045] The light-emitting layer 30 is located between the first electrode layer 10 and the second electrode layer 20. The light-emitting layer 30 further includes a third light-emitting unit 32. The electron transport layer 40 further includes a second electron transport unit 43 located between the third light-emitting unit 32 and the second electrode layer 20. The second electron transport unit 43 connects the first electron transport unit 41 and the multiplexing unit 42.

[0046] Among them, the materials of the first light-emitting unit 31 and the third light-emitting unit 32 include organic polymer light-emitting materials. One of the first light-emitting unit 31 and the third light-emitting unit 32 is used to emit red light, and the other is used to emit green light. The second light-emitting unit 33 is used to emit blue light. For example, if the first light-emitting unit 31 is used to emit red light and the third light-emitting unit 32 is used to emit green light, then the first light-emitting unit 31 and the third light-emitting unit 32 are respectively made of a red organic light-emitting material and a green organic light-emitting material, and the second light-emitting unit 33 is formed by multiplexing of the multiplexing unit 42.

[0047] The first light-emitting unit 31, the third light-emitting unit 32, and the second light-emitting unit 33 are respectively disposed corresponding to the first sub-electrode 11, the second sub-electrode 12, and the third sub-electrode 13. The first light-emitting unit 31 emits red light under the drive of the first sub-electrode 11 and the second electrode layer 20. The third light-emitting unit 32 emits green light under the drive of the second sub-electrode 12 and the second electrode layer 20. The second light-emitting unit 33 emits blue light under the drive of the third sub-electrode 13 and the second electrode layer 20.

[0048] The electron transport layer 40 is located between the light-emitting layer 30 and the second electrode layer 20, and the material of the electron transport layer 40 is a blue quantum dot electroluminescent material, which is an n-type semiconductor material. The electron transport layer 40 can efficiently transport electrons, improve the overall efficiency of the OLED device, and thus improve the performance of the OLED device; at the same time, the multiplexing unit 42 of the electron transport layer 40 is also multiplexed as the second light-emitting unit 33, thereby simplifying the structure of the OLED device.

[0049] The blue quantum dot electroluminescent material has a high photoluminescence quantum yield (PLQY); the structure of the blue quantum dot electroluminescent material is usually a core-shell structure, wrapped with an insulating oleic acid ligand on the periphery, and its charge transport performance is worse than that of the organic transport layer, making its electron transport characteristics superior to its hole transport characteristics; and the thickness range of the electron transport layer formed by the blue quantum dot electroluminescent material is from 10 nanometers to 20 nanometers, such as 10 nanometers, 11 nanometers, 12 nanometers, 13 nanometers, 14 nanometers, 15 nanometers, 16 nanometers, 17 nanometers, 18 nanometers, 19 nanometers, 20 nanometers, etc. Optionally, the blue quantum dot electroluminescent material includes quantum dots of InP core-ZnSe shell, InP core-ZnSe shell-ZnS shell, CdSe core-ZnS shell, and ZnSeTe core-ZnSe shell-ZnS shell.

[0050] In some embodiments, the bandgap range of the blue quantum dot electroluminescent material is from 2.6 eV to 3.0 eV, such as 2.6 eV, 2.7 eV, 2.8 eV, 2.9 eV, 3.0 eV, etc. Optionally, the conduction band energy level of the blue quantum dot electroluminescent material is between the LUMO energy level of the organic polymer light-emitting material and the conduction band of zinc oxide. For example, the LUMO energy level range of the organic polymer light-emitting material is from -2.0 eV to -3.0 eV, and the conduction band range of zinc oxide is from -3.5 eV to -4.0 eV; the valence band energy level of the blue quantum dot electroluminescent material is between the HOMO energy level of the organic polymer light-emitting material and the valence band of zinc oxide. For example, the HOMO energy level range of the organic polymer light-emitting material is from -5.0 eV to -6.0 eV, and the valence band of zinc oxide is -7.0 eV.

[0051] Thus, by using the blue quantum dot electroluminescent material that meets the above conditions, the blue quantum dot electroluminescent material can be used as the electron transport layer 40 and the second light-emitting unit 33.

[0052] Specifically, the electron transport layer 40 can efficiently transport electrons at positions corresponding to the first light-emitting unit 31 and the third light-emitting unit 32, but is not used for light emission; the electron transport layer 40 forms the second light-emitting unit 33 at the position corresponding to the third sub-electrode 13. That is, the second light-emitting unit 33 is a part of the electron transport layer 40. The electron transport layer 40 forming the second light-emitting unit 33 can not only efficiently transport electrons but also be used for light emission.

[0053] In this embodiment, the material of the electron transport layer 40 is a blue quantum dot electroluminescent material, specifically an n-type semiconductor material. This material not only has good electron transport performance but also can emit blue light, thus being multiplexed as the second light-emitting unit 33. By selecting a suitable quantum dot material, the light emission efficiency and stability of the electron transport layer 40 can be further optimized.

[0054] In some embodiments, the light-emitting substrate 100 further includes a hole transport layer 50. The hole transport layer 50 is located between the light-emitting layer 30 and the first electrode layer 10. Optionally, the hole transport layer 50 includes a first hole transport unit 51, a second hole transport unit 52, and a third hole transport unit 53. The first hole transport unit 51, the second hole transport unit 52, and the third hole transport unit 53 are respectively arranged corresponding to the first sub-electrode 11, the second sub-electrode 12, and the third sub-electrode 13. The function of the hole transport layer 50 is to transport holes to ensure effective recombination of holes and electrons in the light-emitting layer 30.

[0055] In other words, the first hole transport unit 51, the second hole transport unit 52, and the third hole transport unit 53 are respectively arranged corresponding to the first light-emitting unit 31, the third light-emitting unit 32, and the multiplexing unit 42 to better adapt to the energy levels of the light-emitting layer. Specifically, the first hole transport unit 51 is located between the first light-emitting unit 31 and the first sub-electrode 11, the second hole transport unit 52 is located between the third light-emitting unit 32 and the second sub-electrode 12, and the third hole transport unit 53 is located between the multiplexing unit 42 and the third sub-electrode 13. That is, the multiplexing unit 42 covers the side of the third hole transport unit 53 away from the first electrode layer 10, and the multiplexing unit 42 is in direct contact with the third hole transport unit 53.

[0056] In other words, in some embodiments, the electron transport layer 40 not only covers the sides of the first light-emitting unit 31 and the third light-emitting unit 32 away from the first electrode layer 10 but also extends to the hole transport layer 50 corresponding to the second light-emitting unit 33 to form the second light-emitting unit 33.

[0057] In some embodiments, the light-emitting substrate 100 further includes a hole injection layer, and the hole injection layer is located between the hole transport layer 50 and the first electrode layer 10. The HOMO energy level of the hole transport layer is distributed between the work function of the hole injection layer and the valence band of the blue quantum dot electroluminescent material. If the HOMO energy level of the hole transport layer is too shallow, holes are not easily injected from the hole transport layer into the blue quantum dot electroluminescent material. If the energy level of the hole transport layer is too deep, there is a large injection barrier between the hole transport layer and the hole injection layer.

[0058] In some embodiments, the light-emitting substrate 100 further includes a hole blocking layer. In this embodiment, since the blue quantum dot electroluminescent material forming the electron transport layer 40 satisfies the characteristics of the blue quantum dot electroluminescent material described above, the electron transport layer 40 can also be reused as the hole blocking layer, thereby further simplifying the structure of the OLED device. Moreover, the hole blocking layer can also prevent holes from diffusing to the second electrode layer 20, thereby improving the efficiency and stability of the device. Specifically, the introduction of the hole blocking layer can reduce the loss of charges and the reduction of voltage. It can limit the flow of holes, so that more charges recombine and emit light in the organic light-emitting layer 30, thereby improving the light-emitting efficiency; the existence of the hole blocking layer can reduce the interaction between the electrode material and the organic light-emitting layer 30, thereby slowing down the aging process of the device and extending the life of the device. That is, by reusing the electron transport layer 40 as the hole blocking layer, it is possible to prevent hole diffusion, improve the light-emitting efficiency, and enhance the device life, thereby further improving the performance of the OLED device. Moreover, by reusing the electron transport layer 40 as the hole blocking layer, there is no need to separately provide the hole blocking layer, which can further simplify the structure of the OLED device.

[0059] In this embodiment, the electron transport layer 40 is reused as the hole blocking layer. Through this design, without adding an additional functional layer, it is possible to effectively prevent holes from diffusing to the second electrode layer 20, thereby improving the efficiency and life of the device. This reuse design simplifies the structure of the OLED device and reduces the manufacturing cost.

[0060] In some embodiments, the embodiments of the present application further provide a method for preparing a light-emitting substrate 100. Refer to Figure 2 , Figure 2 which is a schematic flow chart of the method for preparing a light-emitting substrate provided by the embodiments of the present application. The method for preparing the light-emitting substrate includes the following steps:

[0061] S201: Prepare the first electrode layer 10;

[0062] Specifically, a transparent conductive material (such as ITO) is deposited on a substrate, and a first sub-electrode 11, a second sub-electrode 12, and a third sub-electrode 13 are formed through a photolithography process. The substrate includes a substrate and a driving circuit layer disposed on the substrate.

[0063] S202: Form a first light-emitting unit 31 on the first electrode layer 10 as a part of the light-emitting layer 30;

[0064] Specifically, a first light-emitting unit 31 and a third light-emitting unit 32 are formed on the first electrode layer 10 through evaporation or inkjet printing processes as a part of the light-emitting layer 30. The material of the first light-emitting unit 31 includes a red organic light-emitting material, and the material of the third light-emitting unit 32 includes a green organic light-emitting material.

[0065] S203: Prepare an electron transport layer 40, where the electron transport layer 40 includes a first electron transport unit 41 formed on the first light-emitting unit 31 and a multiplexing unit 42 formed on an adjacent side of the first electron transport unit 41, and the multiplexing unit 42 is multiplexed as a second light-emitting unit 33 of the light-emitting layer 30;

[0066] Specifically, a blue quantum dot electroluminescent material is doped in a n-octane solvent to form printing ink; the printing ink is printed on the first light-emitting unit 31 and the adjacent side of the first light-emitting unit 31 by inkjet printing; the printing ink printed on the first light-emitting unit 31 and the adjacent side of the first light-emitting unit 31 is vacuum-dried to form the first electron transport unit 41 and the multiplexing unit 42. The printing ink uses an alkane such as n-octane as a solvent, and due to the orthogonal effect of the solvent, it will not dissolve the polymers of the first light-emitting unit 31 and the third light-emitting unit 32. In some other embodiments, the printing ink can also use n-heptane, n-nonane, n-decane, and their isomers as solvents.

[0067] In this embodiment, the electron transport layer 40 is formed by an inkjet printing process. This process has the advantages of high precision and low cost, and is particularly suitable for the manufacture of large-area displays. By doping a blue quantum dot electroluminescent material in a n-octane solvent to form printing ink, uniform deposition of the electron transport layer 40 can be achieved, ensuring the light-emitting performance of the second light-emitting unit 33, and due to the orthogonal effect of the solvent, it will not dissolve the polymers of the first light-emitting unit 31 and the third light-emitting unit 32. In addition, by adjusting the parameters of inkjet printing (such as ink concentration, printing speed, etc.), the uniformity and light-emitting performance of the electron transport layer 40 can be further improved. The optimized preparation process not only improves production efficiency but also reduces material waste, having high economic benefits.

[0068] S203: Form a second electrode layer 20 on the electron transport layer 40;

[0069] Specifically, form the second electrode layer 20 on the electron transport layer 40 through an evaporation process as the cathode. The material of the second electrode layer 20 can be a metal material such as aluminum (Al) or silver (Ag).

[0070] Based on the same inventive concept, an embodiment of the present application further provides a display device. The display device includes the light-emitting substrate 100 described in one of the foregoing embodiments or the light-emitting substrate prepared by the light-emitting substrate preparation method described in one of the foregoing embodiments. By using the light-emitting substrate 100 provided in the present application, the display device can achieve higher color performance, lower power consumption, and longer service life, thereby enhancing the user's visual experience. The display device can be applied to various electronic devices such as televisions, mobile phones, tablet computers, and wearable devices.

[0071] According to the above embodiments, it can be known that:

[0072] In a light-emitting substrate, a preparation method thereof, and a display device provided in the present application, the light-emitting substrate includes a first electrode layer and a second electrode layer disposed opposite to each other, a light-emitting layer and an electron transport layer located between the first electrode layer and the second electrode layer. The light-emitting layer includes a first light-emitting unit and a second light-emitting unit. The electron transport layer includes a first electron transport unit located between the first light-emitting unit and the second electrode layer, and a multiplexing unit located on the adjacent side of the first electron transport unit. The multiplexing unit is multiplexed as the second light-emitting unit to simplify the structure of the OLED device while improving the performance of the OLED device.

[0073] In the above embodiments, the descriptions of the respective embodiments have their own focuses. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0074] The above has introduced the embodiments of the present application in detail. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present application; those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A light-emitting substrate, characterized in that: include: a first electrode layer; a second electrode layer, arranged opposite to the first electrode layer; a light-emitting layer, located between the first electrode layer and the second electrode layer, the light-emitting layer comprising a first light-emitting unit and a second light-emitting unit; and an electron transport layer, comprising a first electron transport unit located between the first light-emitting unit and the second electrode layer; Wherein, the electron transport layer further includes a multiplexing unit, and the multiplexing unit is multiplexed into the second light-emitting unit.

2. The light-emitting substrate according to claim 1, characterized in that: The material of the electron transport layer includes blue quantum dot electroluminescent material.

3. The light-emitting substrate according to claim 2, characterized in that: The blue quantum dot electroluminescent material is an n-type semiconductor material, and the band gap range of the blue quantum dot electroluminescent material is 2.6 eV to 3.0 eV.

4. The light-emitting substrate according to claim 2, characterized in that: The light-emitting substrate further includes a hole blocking layer, the electron transport layer is reused as the hole blocking layer, and the thickness of the electron transport layer ranges from 10 nanometers to 20 nanometers.

5. The light-emitting substrate according to any one of claims 1 to 4, characterized in that: The light-emitting layer further includes a third light-emitting unit, the electron transport layer further includes a second electron transport unit located between the third light-emitting unit and the second electrode layer, and the second electron transport unit connects the first electron transport unit and the multiplexing unit; Among them, one of the first light-emitting unit and the third light-emitting unit is used to emit red light, the other is used to emit green light, and the second light-emitting unit is used to emit blue light.

6. The light-emitting substrate according to claim 5, characterized in that: The light-emitting substrate further comprises a hole transport layer, wherein the hole transport layer is located between the light-emitting layer and the first electrode layer; Among them, the hole transport layer includes a first hole transport unit, a second hole transport unit and a third hole transport unit, the first hole transport unit is located between the first light-emitting unit and the first electrode layer, the second hole transport unit is located between the third light-emitting unit and the first electrode layer, and the third hole transport unit is located between the multiplexing unit and the first electrode layer.

7. The light-emitting substrate according to claim 6, characterized in that: The material of the first light-emitting unit includes a red organic light-emitting material, and the material of the third light-emitting unit includes a green organic light-emitting material.

8. A method for preparing a light-emitting substrate, characterized in that: include: preparing a first electrode layer; forming a first light-emitting unit on the first electrode layer as a part of the light-emitting layer; preparing an electron transport layer, the electron transport layer comprising a first electron transport unit formed on the first light-emitting unit and a multiplexing unit formed on an adjacent side of the first electron transport unit, the multiplexing unit being multiplexed as a second light-emitting unit of the light-emitting layer; A second electrode layer is formed on the electron transport layer.

9. The method for preparing a light-emitting substrate according to claim 8, characterized in that: The step of preparing the electron transport layer comprises: Doping a blue quantum dot electroluminescent material in an n-octane solvent to form a printing ink; Printing ink on the first light-emitting unit and adjacent sides of the first light-emitting unit by inkjet printing; The printing ink printed on the first light-emitting unit and the adjacent side of the first light-emitting unit is vacuum dried to form the first electron transport unit and the multiplexing unit.

10. A display device, characterized in that: The invention comprises a light-emitting substrate as claimed in any one of claims 1 to 7 or a light-emitting substrate prepared by the method for preparing a light-emitting substrate as claimed in any one of claims 8 and 9.

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