Light-emitting device and manufacturing method therefor, and display panel

Abstract

Embodiments of the present disclosure relate to the technical field of display, and provide a light-emitting device and a manufacturing method therefor, and a display panel, for use in solving the problem of positive aging present in light-emitting devices. The light-emitting device comprises an anode and a cathode which are arranged oppositely, a light-emitting layer, and a first functional layer. The light-emitting layer is located between the anode and the cathode. The first functional layer is located between the cathode and the light-emitting layer. The first functional layer has a first state and a second state, the first state is the state of the first functional layer before aging treatment, and the second state is the state of the first functional layer after aging treatment. Under the same preset condition, the ratio of the current efficiency of a light-emitting device that has a first functional layer in the first state to the current efficiency of a light-emitting device that has a first functional layer in the second state is greater than or equal to 0.83. The light-emitting device is used in a display apparatus.

Description

Light-emitting device, preparation method thereof and display panel TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of display, and in particular to a light-emitting device, a preparation method thereof and a display panel. BACKGROUND

[0002] As a new type of light-emitting material, quantum dots (QDs) have the advantages of high light color purity, high light-emitting quantum efficiency, adjustable light-emitting color, long service life, etc., and have become a research hotspot of new LED (Light Emitting Diode) light-emitting materials. Therefore, quantum dot light-emitting diodes (QLED) using quantum dot light-emitting materials as light-emitting layers have become the main direction of research on new display devices.

[0003] SUMMARY

[0004] In one aspect, a light-emitting device is provided. The light-emitting device includes an anode and a cathode disposed opposite to each other, a light-emitting layer, and a first functional layer. The light-emitting layer is located between the anode and the cathode. The first functional layer is located between the cathode and the light-emitting layer. The first functional layer has a first state and a second state, the first state being a state before an aging treatment, and the second state being a state after the aging treatment. A ratio between a current efficiency of the light-emitting device including the first functional layer in the first state and a current efficiency of the light-emitting device including the first functional layer in the second state is greater than or equal to 0.83 under the same predetermined conditions.

[0005] In some embodiments, the same predetermined conditions include the same current density and / or the same brightness.

[0006] In some embodiments, the material of the first functional layer includes first nanoparticles, and a particle size of the first nanoparticles is 4 nm to 6 nm.

[0007] In some embodiments, the material of the first functional layer further includes second nanoparticles, and a particle size of the second nanoparticles is smaller than the particle size of the first nanoparticles.

[0008] In some embodiments, the material of the first functional layer includes third nanoparticles, and the third nanoparticles include a first metal oxide material and a first ligand material coordinated to the first metal oxide material. A mass fraction of the first ligand material in the third nanoparticles is 16% to 25%.

[0009] In some embodiments, the material of the first functional layer further comprises fourth nanoparticles, the fourth nanoparticles comprising a second metal oxide material and a second ligand material ligated to the second metal oxide material; and the mass percentage of the second ligand material in the fourth nanoparticles is less than the mass percentage of the first ligand material in the third nanoparticles.

[0010] In some embodiments, the first ligand material comprises ethanolamine; and / or, in the case that the material of the first functional layer comprises fourth nanoparticles, the second ligand material comprises ethanolamine.

[0011] In some embodiments, the first functional layer comprises a first sub-layer, a second sub-layer and a third sub-layer stacked along a first direction. The second sub-layer is located between the first sub-layer and the third sub-layer; and the first direction is the arrangement direction of the anode and the cathode. The material of the second sub-layer has an electron mobility greater than or equal to the electron mobility of the material of the first sub-layer; and / or, the material of the second sub-layer has an electron mobility greater than or equal to the electron mobility of the material of the third sub-layer.

[0012] In some embodiments, in the case that the material of the first functional layer comprises first nanoparticles and second nanoparticles, the first nanoparticles are arranged in the first sub-layer and / or the third sub-layer; and the second nanoparticles are arranged in the second sub-layer.

[0013] In some embodiments, the particle size of the first nanoparticles is 5-6 nm, and the particle size of the second nanoparticles is 3-4 nm.

[0014] In some embodiments, the absolute value of the lowest unoccupied molecular orbital energy level of the material of the second sub-layer is greater than or equal to the absolute value of the lowest unoccupied molecular orbital energy level of the material of the first sub-layer; and / or, the absolute value of the lowest unoccupied molecular orbital energy level of the material of the second sub-layer is greater than or equal to the absolute value of the lowest unoccupied molecular orbital energy level of the material of the third sub-layer.

[0015] In some embodiments, in the case that the material of the first functional layer comprises third nanoparticles and fourth nanoparticles, the third nanoparticles are arranged in the first sub-layer and / or the third sub-layer; and the fourth nanoparticles are arranged in the second sub-layer.

[0016] In some embodiments, the mass percentage of the second ligand material in the fourth nanoparticles is 10-15%.

[0017] In some embodiments, the first nanoparticles comprise a combination of one or any multiple of zinc oxide and doped zinc oxide. In the case that the material of the first functional layer comprises the second nanoparticles, the second nanoparticles comprise a combination of one or any multiple of zinc oxide and doped zinc oxide. In the case that the material of the first functional layer comprises the third nanoparticles, the first metal oxide material comprises a combination of one or any multiple of zinc oxide and doped zinc oxide. In the case that the material of the first functional layer comprises the fourth nanoparticles, the second metal oxide material comprises a combination of one or any multiple of zinc oxide and doped zinc oxide. Herein, the doped zinc oxide is zinc oxide containing a doping element.

[0018] In some embodiments, the mass percentage of the doping element in the doped zinc oxide is 1% to 20%.

[0019] In some embodiments, in the case that the first nanoparticles are arranged in the first sub-layer and / or the third sub-layer and the first nanoparticles comprise zinc oxide, the highest occupied molecular orbital energy level of the first nanoparticles is -7.5 eV to -8.0 eV, and / or the lowest unoccupied molecular orbital energy level of the first nanoparticles is -3.8 eV to -4.0 eV.

[0020] In some embodiments, in the case that the material of the first functional layer further comprises the second nanoparticles arranged in the second sub-layer and the second nanoparticles comprise zinc oxide, the highest occupied molecular orbital energy level of the second nanoparticles is -7.5 eV to -8.0 eV, and / or the lowest unoccupied molecular orbital energy level of the second nanoparticles is -4.0 eV to -4.3 eV.

[0021] In some embodiments, the first functional layer comprises a first electron transport thin film.

[0022] In some embodiments, the light-emitting device is arranged on a substrate; the cathode is closer to the substrate relative to the anode.

[0023] In some embodiments, the first functional layer further comprises a second electron transport thin film. The first electron transport thin film is closer to the cathode relative to the second electron transport thin film. The absolute value of the lowest unoccupied molecular orbital energy level of the material of the second electron transport thin film is smaller than the absolute value of the lowest unoccupied molecular orbital energy level of the material of the first electron transport thin film, and is larger than the absolute value of the lowest unoccupied molecular orbital energy level of the material of the light-emitting layer.

[0024] In some embodiments, the lowest unoccupied molecular orbital energy level of the material of the first electron transport thin film is -4.7 eV to -4.2 eV; and / or the lowest unoccupied molecular orbital energy level of the material of the second electron transport thin film is -4.2 eV to -3.8 eV.

[0025] In some embodiments, a ratio between a size of the first electron transport thin film along the first direction and a size of the second electron transport thin film along the first direction ranges from 1:1 to 3:1, the first direction being a direction in which the anode and the cathode are arranged.

[0026] In some embodiments, the material of the first electron transport thin film comprises zinc oxide. The material of the second electron transport thin film comprises doped zinc oxide, the doped zinc oxide being zinc oxide containing a doping element.

[0027] In some embodiments, a mass percentage of the doping element in the doped zinc oxide is greater than 0% and less than or equal to 10%.

[0028] In some embodiments, in a case where one or more of the first nanoparticles, the second nanoparticles, the first metal oxide material, and the second metal oxide material comprises doped zinc oxide, or in a case where the material of the second electron transport thin film comprises doped zinc oxide, the doping element comprises one or a combination of any multiple of lithium, magnesium, aluminum, gallium, yttrium, and copper.

[0029] In some embodiments, the light emitting device further comprises a blocking layer. The blocking layer is located between the light emitting layer and the anode. The blocking layer is configured to prevent electrons from leaking to a side of the light emitting layer away from the first functional layer.

[0030] In another aspect, a method of manufacturing a light emitting device is provided. The method comprises forming an anode, a cathode, a light emitting layer, and a first functional layer. The anode and the cathode are arranged opposite to each other; the light emitting layer is located between the anode and the cathode; the first functional layer is located between the cathode and the light emitting layer; the first functional layer has a first state and a second state, the first state being a state before an aging treatment, and the second state being a state after the aging treatment; and a ratio between a current efficiency of the light emitting device containing the first functional layer in the first state and a current efficiency of the light emitting device containing the first functional layer in the second state under a same preset condition is greater than or equal to 0.83.

[0031] In some embodiments, forming the first functional layer comprises: spin-coating a first solution on the light emitting layer, the first solution being used to form a first sub-layer, the first sub-layer constituting a part of the first functional layer; spin-coating a second solution on a side of the first sub-layer away from the light emitting layer, the second solution being used to form a second sub-layer, the second sub-layer constituting another part of the first functional layer; and spin-coating a third solution on a side of the second sub-layer away from the first sub-layer, the third solution being used to form a third sub-layer, the third sub-layer constituting a further part of the first functional layer. A molecular chain length of a solvent contained in the first solution is less than a molecular chain length of a solvent contained in the second solution; a molecular chain length of a solvent contained in the second solution is less than or equal to a molecular chain length of a solvent contained in the third solution.

[0032] In some embodiments, forming the anode, the cathode, the light-emitting layer, and the first functional layer comprises: forming a patterned cathode on the substrate; forming a first electron transport thin film on a side of the cathode distal to the substrate, the first electron transport thin film constituting at least part of the first functional layer; forming the light-emitting layer on a side of the first electron transport thin film distal to the cathode; and forming the anode on a side of the light-emitting layer distal to the first functional layer. Forming the first electron transport thin film comprises forming the first electron transport thin film on the side of the cathode distal to the substrate by a sputtering process, or forming the first electron transport thin film on the side of the cathode distal to the substrate by a sol-gel process.

[0033] In some embodiments, forming the anode, the cathode, the light-emitting layer, and the first functional layer further comprises: forming a second electron transport thin film on a side of the first electron transport thin film distal to the cathode by a sputtering process, or forming the second electron transport thin film on a side of the first electron transport thin film distal to the cathode by a sol-gel process. The second electron transport thin film constitutes part of the first functional layer. An absolute value of a lowest unoccupied molecular orbital energy level of a material of the second electron transport thin film is smaller than an absolute value of a lowest unoccupied molecular orbital energy level of a material of the first electron transport thin film, and is larger than an absolute value of a lowest unoccupied molecular orbital energy level of a material of the light-emitting layer.

[0034] In another aspect, a display panel is provided. The display panel comprises: a plurality of pixel driving circuits and a plurality of light-emitting devices as described in any of the above embodiments. The pixel driving circuits are configured to drive the light-emitting devices to emit light.

[0035] In some embodiments, the display panel further comprises a substrate and an encapsulation layer. The plurality of light-emitting devices are disposed on a side of the substrate. The encapsulation layer is disposed on a side of the plurality of light-emitting devices distal to the substrate. A material of the encapsulation layer comprises a neutral organic material and / or a basic organic material. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the present disclosure, the following will briefly introduce the drawings needed to be used in some embodiments of the present disclosure. Obviously, the drawings described in the following description are only the drawings of some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art according to these drawings. In addition, the drawings described in the following description can be regarded as schematic diagrams, and are not limited to the actual size, actual process, actual timing of signals, etc. of the products involved in the embodiments of the present disclosure.

[0037] FIG. 1 is a structural diagram of a display panel according to some embodiments;

[0038] FIG. 2 is a structural diagram of a display panel according to some other embodiments;

[0039] FIG. 3 is a structural diagram of a display panel according to some other embodiments;

[0040] FIG. 4 is a structural diagram of a display panel according to still other embodiments;

[0041] FIG. 5 is a structural diagram of a display panel according to still other embodiments;

[0042] FIG. 6 is a step diagram of a method of manufacturing a display panel according to some embodiments;

[0043] FIG. 7 is a flow diagram of a method of manufacturing a light-emitting device according to some embodiments;

[0044] FIG. 8 is a step diagram of a light-emitting device of a display panel according to some embodiments;

[0045] FIG. 9 is a step diagram of a light-emitting device of a display panel according to still other embodiments;

[0046] FIG. 10 is a step diagram of a light-emitting device of a display panel according to still other embodiments;

[0047] FIG. 11 is a UV absorption spectrum of nanoparticles in a first functional layer according to some embodiments;

[0048] FIG. 12 is a transmission electron microscope image of nanoparticles in a first functional layer according to some embodiments;

[0049] FIG. 13 is a plot of current efficiency versus luminance for a light-emitting device according to some embodiments;

[0050] FIG. 14 is a plot of current efficiency versus luminance for a light-emitting device according to still other embodiments;

[0051] FIG. 15 is a plot of current efficiency versus luminance for a light-emitting device according to still other embodiments;

[0052] FIG. 16 is a plot of current efficiency versus luminance for a light-emitting device according to still other embodiments;

[0053] FIG. 17 is a plot of current efficiency versus luminance for a light-emitting device according to still other embodiments;

[0054] FIG. 18 is a plot of current efficiency versus luminance for a light-emitting device according to still other embodiments;

[0055] FIG. 19 is a plot of current efficiency versus luminance for a light-emitting device according to still other embodiments;

[0056] FIG. 20 is a structural diagram of a display panel according to still other embodiments;

[0057] FIG. 21 is a structural diagram of a display panel according to still other embodiments;

[0058] FIG. 22 is a graph of luminance versus voltage for a light-emitting device according to yet other embodiments;

[0059] FIG. 23 is a graph of current density versus voltage and luminance versus voltage for a light-emitting device according to yet other embodiments;

[0060] FIG. 24 is a graph of current efficiency versus current density for a light-emitting device according to yet other embodiments;

[0061] FIG. 25 is a structural diagram of a light-emitting device according to some embodiments;

[0062] FIG. 26 is a structural diagram of a light-emitting device according to yet other embodiments;

[0063] FIG. 27 is an electron transport schematic of a light-emitting device according to some embodiments;

[0064] FIG. 28 is an electron transport schematic of a light-emitting device according to yet other embodiments. DETAILED DESCRIPTION

[0065] The technical solutions in some embodiments of the present disclosure will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided in the present disclosure, all other embodiments obtained by a person of ordinary skill in the art fall within the scope of protection of the present disclosure.

[0066] Unless otherwise required by context, the term “comprise” and other forms of the term “comprise”, such as “comprises” and “comprising”, are to be construed as open, inclusive, meaning, i.e., “including, but not limited to”, in the entire specification and claims. In the description of the specification, the terms “one embodiment”, “some embodiments”, “exemplary embodiments”, “example”, “specific example” or “some examples” are intended to mean that the particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of the present disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. In addition, the particular features, structures, materials, or characteristics described can be included in any suitable manner in any one or more embodiments or examples.

[0067] Hereinafter, the terms "first", "second", "third", etc. are used only for the purpose of description, and are not to be construed as indicating or implying relative importance or a specific number of the technical features indicated. Thus, the features defined with "first", "second", "third" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0068] "A, B, and C at least one of" has the same meaning as "at least one of A, B, or C", and includes the following combinations of A, B, and C: only A, only B, only C, a combination of A and B, a combination of A and C, a combination of B and C, and a combination of A, B, and C.

[0069] "A and / or B" includes the following three combinations: only A, only B, and a combination of A and B.

[0070] As used herein, "about", "approximately", or "around" includes the stated value and the average value within an acceptable range of deviation from the stated value, as determined by one of ordinary skill in the art considering the measurement in question and the error in measuring the particular quantity (i.e., the limitations of the measurement system).

[0071] As used herein, "parallel", "perpendicular", "equal" includes the stated case and a case similar to the stated case, the similar case being within an acceptable range of deviation, wherein the acceptable range of deviation is determined by one of ordinary skill in the art considering the measurement in question and the error in measuring the particular quantity (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallel and approximately parallel, wherein the acceptable range of deviation for approximately parallel may, for example, be within 5°; "perpendicular" includes absolute perpendicular and approximately perpendicular, wherein the acceptable range of deviation for approximately perpendicular may, for example, also be within 5°. "Equal" includes absolute equality and approximate equality, wherein the acceptable range of deviation for approximate equality may, for example, be a difference between the two of less than or equal to 5% of either.

[0072] It should be understood that when a layer or element is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening layers can also be present.

[0073] Exemplary embodiments are described herein with reference to cross-sectional and / or plan view illustrations that are schematic and are not intended to be ascribed to planar or cross-sectional geometries of structures. In other words, the exemplary embodiments are not intended to be limited to the precise arrangements and relative geometries illustrated herein, but are intended to encompass variations that are apparent to persons of ordinary skill in the art given the benefit of this disclosure. For example, relative sizes of regions shown in the drawings can be exaggerated, for purposes of clarity and illustration. Thus, the exemplary embodiments should not be construed as limited to the precise structures illustrated herein, but rather, are to cover all modifications, equivalents, and alternatives falling within the scope of the exemplary embodiments. Like numbers refer to like elements throughout.

[0074] It should be noted that, in the drawings of the present disclosure, for example, 11-1 indicates that the component 11 belongs to the component 1, for example, 221-220 in FIG. 2 indicates that the pixel defining layer 221 belongs to the light emitting functional layer 220, and other similar notations appearing in the drawings also follow the above description. For example, 1 / 2 appearing in the drawings of the present disclosure indicates that both the structure 1 and the structure 2 can refer to the structure, for example, 101 / 100 in FIG. 2 indicates that both the first light emitting device 101 and the light emitting device 100 can be represented by the structure. Other similar notations appearing in the drawings also follow the above description.

[0075] As shown in FIG. 1, some embodiments of the present disclosure provide a display panel 200, which includes a plurality of light emitting devices 100 and a plurality of pixel driving circuits 231.

[0076] The display panel 200 described above may, for example, be a quantum dot light emitting diode (QLED) display panel, in which case the light emitting device 100 is a QLED light emitting device. Based on the quantum confinement effect, quantum dots (QDs) can be used as new light emitting materials for light emitting diodes (LEDs), and have the advantages of high light color purity, high light emitting quantum efficiency, adjustable light emitting color, long service life, and the like. Therefore, QLEDs using quantum dots as light emitting materials are considered to be the most potential next-generation self-emitting display technology, and are widely used in display lighting, solar cells, and photoelectric detection fields.

[0077] The display panel 200 described above can be applied to a display device. The display device can be any display device that displays both motion (e.g., video) and still (e.g., still images) and both text and images. More specifically, it is contemplated that the display panel of the embodiments described herein can be implemented in or associated with a variety of electronic devices such as, but not limited to, mobile telephones, wireless devices, personal data assistants (PDAs), handheld or portable computers, GPS receivers / navigators, cameras, MP3 players, camcorders, game consoles, watches, clocks, calculators, television monitors, flat-panel displays, computer monitors, auto displays (e.g., odometer display, etc.), cockpit controls and / or displays, camera view displays (e.g., display of a rear view camera in a vehicle), electronic photographs, electronic billboards or signs, projections, architectural structures, packaging, and aesthetic structures (e.g., display of images on a piece of jewelry), and the like.

[0078] In some embodiments, as shown in FIG. 1, the display panel 200 described above includes a substrate 210 and a light-emitting functional layer 220 disposed on one side of the substrate 210, the light-emitting functional layer 220 including a plurality of light-emitting devices 100. That is, the plurality of light-emitting devices 100 can be disposed on one side of the substrate 210.

[0079] Exemplarily, the plurality of light-emitting devices 100 can be arranged along a second direction Y, for example, a direction parallel to the plane on which the substrate 210 lies.

[0080] Exemplarily, the material of the substrate 210 can be a rigid material, for example, glass, to realize a rigid substrate display; or the material of the substrate 210 can also be a flexible material, for example, polyimide (PI) or polyethylene glycol terephthalate (PET), to realize a flexible substrate display.

[0081] In some examples, as shown in FIG. 1, the display panel 200 further includes a driving circuit layer 230 disposed between the substrate 210 and the light-emitting functional layer 220, the driving circuit layer 230 including a plurality of pixel driving circuits 231.

[0082] Exemplarily, in the display panel 200, the pixel driving circuit 231 can generate a driving current. Each light-emitting device 100 can emit light under the driving action of the driving current generated by the corresponding pixel driving circuit 231, and the light emitted by the plurality of light-emitting devices 100 cooperates with each other, so that the display panel 200 realizes a display function.

[0083] In some examples, the driving circuit layer 230 includes cathodes and anodes in a longitudinal and transverse crossbar, and the parts where the rows and columns cross can emit light. At this time, the pixel driving circuit 231 does not employ TFT technology, and the display panel 200 can be referred to as a passive driving display panel (for example, a passive driving QLED display panel, a PMQLED display panel).

[0084] In other examples, the driving circuit layer 230 includes a plurality of pixel driving circuits 231 arranged in an array, and the pixel driving circuit 231 includes a plurality of transistors TFT. The pixel driving circuit 231 is electrically connected to the light emitting device 100, and is used to drive the light emitting device 100 to emit light. At this time, the pixel driving circuit 231 employs TFT technology, and the display panel 200 can be referred to as an active driving display panel (for example, an active driving QLED display panel, an AMQLED display panel). Among them, the AMQLED display panel has attracted more and more attention due to its potential advantages in wide color gamut, long life, etc., and the quantum efficiency is constantly improving, basically reaching the level of industrialization.

[0085] In some examples, as shown in FIG. 1, the display panel 200 further includes an encapsulation layer 240, which can be arranged on the side of the plurality of light emitting devices 100 away from the substrate 210.

[0086] For example, the driving circuit layer 230, the light emitting functional layer 220, and the encapsulation layer 240 can be stacked on the substrate 210, and the driving circuit layer 230, the light emitting functional layer 220, and the encapsulation layer 240 are arranged in sequence away from the substrate 210.

[0087] For example, the display panel 200 can be a QLED display panel 200, and at this time, the encapsulation layer 240 covers the light emitting device 100, and encapsulates the light emitting device 100, so as to avoid water vapor and oxygen in the external environment from entering the display panel 200, damaging the material in the light emitting device 100, and causing the service life of the QLED display panel 200 to be shortened.

[0088] In some embodiments, as shown in FIGS. 1 and 2, the display panel 200 further includes a pixel defining layer 221, and the pixel defining layer 221 has a plurality of openings Q, and the plurality of light emitting devices 100 can be arranged one-to-one with the plurality of openings Q.

[0089] In some embodiments, as shown in FIG. 2, the plurality of light emitting devices 100 of the display panel 200 includes at least one first light emitting device 101, at least one second light emitting device 102, and at least one third light emitting device 103. Under the action of a driving voltage, the first light emitting device 101 is configured to emit light of a first color (e.g., blue light), the second light emitting device 102 is configured to emit light of a second color (e.g., green light), and the third light emitting device 103 is configured to emit light of a third color (e.g., red light). In this way, the brightness (gray scale) of the first light emitting device 101, the second light emitting device 102, and the third light emitting device 103 can be adjusted respectively, and a variety of colors can be displayed through color combination and superposition, thereby realizing full-color display of the display panel 200.

[0090] In some embodiments, as shown in FIGS. 1-3, the light emitting device 100 includes an anode 110 and a cathode 120 arranged opposite to each other, and a light emitting layer 130 arranged between the anode 110 and the cathode 120.

[0091] It should be understood that, as shown in FIGS. 2 and 3, in the case where the plurality of light emitting devices 100 of the display panel 200 includes at least one first light emitting device 101, at least one second light emitting device 102, and at least one third light emitting device 103, the materials of the light emitting layer 131 of the first light emitting device 101, the light emitting layer 132 of the second light emitting device 102, and the light emitting layer 133 of the third light emitting device 103 are not the same, in order to achieve the purpose of emitting light of different colors.

[0092] Exemplarily, the anode 110 and the cathode 120 can be arranged opposite to each other along a first direction X, and the first direction X intersects (e.g., is perpendicular to) the second direction Y.

[0093] In some examples, as shown in FIG. 2, the anode 110 can be located on the side of the light emitting layer 130 close to the substrate 210, and the cathode 120 can be located on the side of the light emitting layer 130 away from the substrate 210. At this time, the light emitting device 100 can be referred to as a normal light emitting device.

[0094] In other examples, as shown in FIG. 3, the anode 110 can be located on the side of the light emitting layer 130 close to the substrate 210, and the cathode 120 can be located on the side of the light emitting layer 130 away from the substrate 210. At this time, the light emitting device 100 can be referred to as an inverted light emitting device.

[0095] Exemplarily, the material of the anode 110 can be a conductive metal oxide material (e.g., a transparent conductive metal oxide material), such as Indium Tin Oxide (ITO), fluorine-doped tin oxide (FTO), or Indium Zinc Oxide (IZO), etc., where the IZO is formed by, for example, deposition by magnetron sputtering; or the material of the anode 110 can be a conductive polymer (e.g., a transparent conductive polymer); or the material of the anode 110 can be a metal material (e.g., a non-transparent metal material), such as aluminum (Al), silver (Ag), or magnesium-silver alloy (Mg:Ag), etc.

[0096] Exemplarily, the thickness of the anode 110 can be 10 nm to 100 nm, such as 10 nm, 30 nm, 42 nm, 50 nm, 70 nm, 90 nm, or 100 nm, etc.

[0097] Exemplarily, the material of the cathode 120 can be a conductive metal oxide material (e.g., a transparent conductive metal oxide material), such as Indium Tin Oxide (ITO), fluorine-doped tin oxide (FTO), or Indium Zinc Oxide (IZO), etc., where the IZO is formed by, for example, deposition by magnetron sputtering; or the material of the cathode 120 can be a conductive polymer (e.g., a transparent conductive polymer); or the material of the cathode 120 can be a metal material (e.g., a non-transparent metal material), such as aluminum (Al) or silver (Ag), etc.

[0098] Exemplarily, the thickness of the cathode 120 can be 10 nm to 100 nm, such as 10 nm, 30 nm, 50 nm, 61 nm, 70 nm, 90 nm, or 100 nm, etc.

[0099] In some embodiments, among the anode 110 and the cathode 120 in the light emitting device 100, the one closer to the substrate 210 can be referred to as a bottom electrode, and the bottom electrode is formed prior to the pixel defining layer 221, such that the edge portion of the pixel defining layer 221 covers the edge portion of the bottom electrode. For example, as shown in FIGS. 1, 2, and 4, the bottom electrode is the anode 110, and the edge portion of the pixel defining layer 221 covers the edge portion of the anode 110; or for example, as shown in FIGS. 3 and 5, the bottom electrode is the cathode 120, and the edge portion of the pixel defining layer 221 covers the edge portion of the cathode 120.

[0100] Exemplarily, when the edge portion of the pixel defining layer 221 covers the edge portion of the bottom electrode, the portion where the pixel defining layer 221 overlaps with the bottom electrode can have a size of 1 μm to 5 μm along the second direction Y, for example, 1 μm, 2 μm, 3 μm, 3.5 μm, 4 μm or 5 μm, etc.

[0101] In some embodiments, as shown in FIG. 2, in the case where the plurality of light emitting devices 100 include a first light emitting device 101, a second light emitting device 102 and a third light emitting device 103, the cathode 120 of the plurality of light emitting devices 100 is a structure of whole-layer communication, i.e., the cathode 120 can be a common electrode shared by the plurality of light emitting devices 100.

[0102] Exemplarily, as shown in FIG. 2, when the cathode 120 is a common electrode shared by the plurality of light emitting devices 100, the cathode 120 is formed on the side of the pixel defining layer 221 away from the substrate 210.

[0103] In some examples, the light emitting layer 130 is a quantum dot light emitting layer. In operation, a voltage is applied on the anode 110 and the cathode 120 respectively, so that an electric field is generated between the anode 110 and the cathode 120, and holes from the anode 110 and electrons from the cathode 120 can be driven to recombine in the quantum dot light emitting layer 130, thereby emitting light.

[0104] Exemplarily, the thickness (i.e., the size along the first direction X) of the light emitting layer 130 can be 20 nm to 50 nm, for example, 20 nm, 25 nm, 30 nm, 34 nm, 40 nm or 50 nm.

[0105] Exemplarily, the material forming the quantum dot light emitting layer includes quantum dot light emitting material and photosensitive material; wherein the quantum dot light emitting material includes quantum dot body and ligand material arranged on the quantum dot body. The photosensitive material is configured to: under the condition of light radiation, cross-linking reaction occurs with the ligand material to generate cross-linked quantum dot light emitting material. Through the above setting, the quantum dot light emitting layer can be formed by a photoetching process. Specifically, by using photochemical reactions such as decomposition or cross-linking of photosensitive groups, the colloidal stability of quantum dots changes before and after photochemical reactions, and through development, the purpose of selective patterning is achieved.

[0106] In some examples, the quantum dot body can include any one or more of II-VI quantum dots, III-V quantum dots, IV-VI quantum dots, IV quantum dots, I-III-VI quantum dots, I-II-IV-VI quantum dots, quantum dots with core-shell structure, and ABX3 type perovskite quantum dots in any combination.

[0107] Among them, the group II-VI quantum dots can be selected from one or more of binary compounds such as CdS, CdSe, CdTe, ZnS, ZnO, ZnSe, ZnTe, HgSe, HgTe and HgS; ternary compounds such as Hg x Cd 1-x Te, Hg x Cd 1-x S, Hg x Cd 1-x Se, Hg x Zn 1-x Te, Cd x Zn 1-x Se, Cd x Zn 1-x S and ZnTeSe, wherein 0

[0108] The group III-V quantum dots can be selected from InP, InAs, InSb, GaAs, GaP, GaN, GaSb, GaNk, InN, AlP, AlN, AlAs, InGaAs, InGaN, or a mixture thereof; but not limited thereto.

[0109] The group IV-VI quantum dots can be selected from PbS, PbSe, PbTe, or a mixture thereof; but not limited thereto.

[0110] The quantum dots with core-shell structure refer to one material as the core and the other material as the shell. For example, the quantum dots of CdS@ZnS refer to the material of the core of the quantum dots as CdS and the material of the shell as ZnS. The quantum dots with core-shell structure can be selected from one or more of CdS@ZnS, CdSe@CdS, InP@ZnS, CdTe@CdSe, CdSe@ZnTe, CdSe@ZnS, PdS@ZnS, ZnTe@CdSe, ZnSe@CdS and Cd 1-x Zn x S@ZnS, wherein 0

[0111] In the ABX3 type perovskite quantum dots, A can be one or more of CH3NH3 + (methylamine), NH2CH=NH2(formamidine) and Cs + , B can be one or two of Pb 2+ and Sn 2+ , and X can be Cl - , Br - and I -The ABX3 type perovskite quantum dots can include CH3NH3PbBr3, CH3NH3PbCl3, CH3NH3PbI3, CsPbBr3, CsPbCl3, and CsPbI3, but are not limited thereto.

[0112] When the plurality of quantum dots are combined, the quantum dot body can be one of CsPbCl3 / ZnS, CsPbBr3 / ZnS, CsPhI3 / ZnS, CdS / ZnSeS / ZnS, CdSe / ZnSeS / ZnS, ZnSe / ZnSeS / ZnS, and ZnSeTe / ZnSeS / ZnS.

[0113] In other examples, the quantum dot body can be other nanoscale materials, such as nanorods, nanosheets, etc. The composition of the other nanoscale materials can include at least one of CuInS2, CuInSe2, AgInS2, etc., but is not limited thereto.

[0114] Exemplarily, the shape of the quantum dot body can be any geometric shape such as a spherical shape, an ellipsoidal shape, a polyhedral shape, a rod shape, a cross shape, a ring shape, etc.

[0115] In some examples, the ligand material can be selected from any one or a combination of organic acids, organic amines, organic phosphorus, and organic thiols, for example, the ligand material can be oleic acid, oleylamine, or dodecanethiol, etc.

[0116] In some implementations, the QLED light-emitting device has a positive aging problem. Specifically, within a certain period of time after initial power-on, the efficiency (e.g., current efficiency) of the QLED light-emitting device shows a significant increase (e.g., 20% to 50% or even higher efficiency improvement), and there is no obvious regularity, sometimes accompanied by a significant decrease in turn-on voltage. This phenomenon makes it difficult for the pixel driving circuit 231 of each light-emitting device 100 in the display panel 200 to coordinate and unify, making it difficult for the driving circuit 231 to be designed to meet actual needs. Therefore, an accelerated positive aging process step needs to be added in the preparation method of the display panel 200, so that the light-emitting device 100 can reach the maximum efficiency in a shorter period of time.

[0117] However, in actual applications, due to the addition of the accelerated positive aging step in the preparation method of the display panel 200, there are problems of complicated process steps, poor process controllability, and poor process repeatability.

[0118] Based on this, some embodiments of the present disclosure provide a light emitting device 100, as shown in FIG. 2 and FIG. 3, which comprises a first functional layer 140. The first functional layer 140 is located between the cathode 120 and the light emitting layer 130. The first functional layer 140 has a first state and a second state, the first state being the state before aging treatment, and the second state being the state after aging treatment; wherein under the same preset conditions, the ratio between the current efficiency (hereinafter referred to as the first current efficiency) of the light emitting device 100 containing the first functional layer 140 in the first state and the current efficiency (hereinafter referred to as the second current efficiency) of the light emitting device 100 containing the first functional layer 140 in the second state is greater than or equal to 0.83.

[0119] In some examples, the first functional layer 140 can be configured to transport electrons. In this way, by setting the first functional layer 140, it is equivalent to setting a transition step between the cathode 120 and the light emitting layer 130, reducing the potential barrier height that the carrier (for example: electrons) needs to overcome, so that the light emitting efficiency is higher.

[0120] In some examples, in the display panel 200, the thickness of the first functional layer 140 of the first light emitting device 101 for emitting blue light, the thickness of the first functional layer 140 of the second light emitting device 102 for emitting green light, and the thickness of the first functional layer 140 of the third light emitting device 103 for emitting red light can be the same or different. Here, the thickness of the first functional layer 140 is the size of the first functional layer 140 along the first direction X.

[0121] Illustratively, the thickness of the first functional layer 140 of the first light emitting device 101 for emitting blue light can be less than the thickness of the first functional layer 140 of the second light emitting device 102 for emitting green light; the thickness of the first functional layer 140 of the second light emitting device 102 for emitting green light can be less than the thickness of the first functional layer 140 of the third light emitting device 103 for emitting red light. For example: the thickness of the first functional layer 140 of the first light emitting device 101 for emitting blue light can be 20 nm; the thickness of the first functional layer 140 of the second light emitting device 102 for emitting green light is 40 nm; the thickness of the first functional layer 140 of the third light emitting device 103 for emitting red light is 60 nm.

[0122] In some examples, the aging treatment method is a combination of one or more of electrical aging and acid treatment aging.

[0123] When the aging treatment method includes electrical aging, the light emitting device 100 can be treated by applying a voltage to accelerate the positive aging process.

[0124] When the aging treatment method includes acid treatment aging, as one possible implementation, a saturated or unsaturated carboxylic acid (e.g., acrylic acid) or the like active ingredient can be added to the material (e.g., encapsulation glue) of the encapsulation layer 240 of the light emitting device 100, and the encapsulated device can be treated (e.g., heat treatment) to accelerate the positive aging process. As another possible implementation, the light emitting device 100 or a portion of the film layer of the light emitting device 100 can be placed in a saturated or unsaturated carboxylic acid (e.g., acrylic acid) atmosphere during the preparation of the display panel 200 to accelerate the positive aging process.

[0125] In some embodiments, the same preset condition includes the same current density and / or the same brightness.

[0126] For example, when the same preset condition includes the same brightness, the range of brightness is greater than 0 and less than or equal to 15000 cd / m 2 For example, the brightness can be 10 cd / m 2 , 100 cd / m 2 , 1000 cd / m 2 , 5000 cd / m 2 , 10000 cd / m 2 , or 15000 cd / m 2 , etc.

[0127] For example, under the same preset condition, the ratio between the first current efficiency and the second current efficiency can be 0.83, 0.85, 0.90, 0.93, 0.95, 1.00, 1.10, or 1.25, etc.

[0128] Here, when the ratio between the first current efficiency and the second current efficiency is greater than 1.00, the light emitting device 100 containing the first functional layer 140 in the second state exhibits a negative aging phenomenon relative to the light emitting device 100 containing the first functional layer 140 in the first state. That is, the light emitting device 100 in some embodiments of the present disclosure can exhibit a negative aging phenomenon before and after the aging treatment, or can not exhibit a negative aging phenomenon before and after the aging treatment, which is not limited here.

[0129] It should be understood that when the ratio between the first current efficiency and the second current efficiency is greater than or equal to 0.83, the first current efficiency is less than the second current efficiency, and the second current efficiency has a growth rate of less than 20% relative to the first current efficiency, or the first current efficiency is greater than the second current efficiency.

[0130] It can be understood that, as described above, the aging process can accelerate the positive aging process, so that the light emitting device 100 can complete the positive aging in a shorter time. Therefore, by setting the ratio between the first current efficiency and the second current efficiency to be greater than or equal to 0.83, the positive aging trend caused by the first functional layer 140 can be relatively small, in other words, the problem of positive aging caused by the first functional layer 140 can be alleviated, so that the problem of positive aging of the light emitting device 100 can be alleviated. In this way, the display panel 200 can achieve a higher light emitting efficiency without the process step of accelerated positive aging, and the process step of accelerated positive aging in the preparation process of the display panel 200 can be omitted. In this way, the preparation process of the display panel 200 can be simplified, and the controllability and repeatability of the preparation process of the display panel 200 can be improved.

[0131] Based on the above setting, in some embodiments, as shown in FIG. 1, the material of the encapsulation layer 240 in the display panel 200 includes a neutral organic material and / or a basic organic material.

[0132] In some examples, the encapsulation layer 240 includes a first inorganic encapsulation layer, a first organic encapsulation layer, and a second inorganic encapsulation layer arranged in sequence in a direction away from the light emitting device 100. In this case, the material of the first organic encapsulation layer includes the neutral organic material and / or the basic organic material described above.

[0133] Here, the neutral organic material is, for example, a neutral resin material. The basic organic material is, for example, a basic resin material.

[0134] As described above, the accelerated positive aging of the light emitting device 100 can be achieved by adding active ingredients such as saturated or unsaturated carboxylic acids (for example, acrylic acid) to the material of the encapsulation layer 240. When the ratio between the first current efficiency and the second current efficiency is greater than or equal to 0.83, the process and measures of accelerated positive aging in the preparation process of the display panel 200 can be omitted, that is, it is not necessary to add saturated or unsaturated carboxylic acids (for example, acrylic acid) to the material of the encapsulation layer 240. Therefore, the neutral organic material and / or the basic organic material can be used to achieve the encapsulation of the display panel 200.

[0135] In some embodiments, as shown in FIG. 2 and FIG. 3, the material of the first functional layer 140 includes nanoparticles.

[0136] It should be understood that when the material of the first functional layer 140 includes nanoparticles, the first functional layer 140 has solution processability, and the formation process of the first functional layer 140 can be simplified. For example, the material (including nanoparticles) of the first functional layer 140 can be formed by spin coating to form the first functional layer 140.

[0137] In some embodiments, there are certain surface defects (e.g., -OH or oxygen vacancies) on the surface of the nanoparticles. When the nanoparticles have a large number of surface defects, they are easily affected by positive aging, that is, are easily subject to positive aging.

[0138] Here, as one possible way of affecting, when the nanoparticles have a large number of surface defects, the nanoparticles have a strong quenching effect on the excitons generated by the quantum dot light-emitting layer, resulting in a low efficiency of the light-emitting device 100, and after being treated by the above-mentioned accelerated positive aging process step, the surface defects of the nanoparticles can be reduced, the quenching effect of the nanoparticles on the excitons generated by the quantum dot light-emitting layer can be weakened, and the efficiency of the light-emitting device 100 can be improved.

[0139] As another possible way of affecting, the active hydrogen on the surface of the nanoparticles can play a role of a shallow donor in the first functional layer 140, can provide excess electrons, and can improve the conductivity of the nanoparticles, so as to increase the injection of electrons into the quantum dot light-emitting layer, and then through the coulomb effect, the holes accumulated at the interface between the quantum dot light-emitting layer and the film layer (e.g., the hole transport layer described in detail below) located on the side away from the first functional layer 140 are pulled into the quantum dot light-emitting layer, so that the brightness and efficiency of the light-emitting device 100 are improved.

[0140] In some embodiments, as shown in FIGS. 2 and 3, the material of the first functional layer 140 includes first nanoparticles, and the particle size of the first nanoparticles is 4 nm to 6 nm.

[0141] Exemplarily, the particle size of the first nanoparticles is 4 nm, 4.5 nm, 5 nm, 5.2 nm, 5.4 nm, 5.5 nm, 5.8 nm, or 6 nm, etc.

[0142] It can be understood that when the particle size of the first nanoparticles is small, the specific surface area of the first nanoparticles is large, the surface defect density of the first nanoparticles is high, and the first nanoparticles are easily affected by the positive aging effect, that is, the positive aging phenomenon is easily generated. When the particle size of the first nanoparticles is large, the electron mobility is relatively low, and the electron transport efficiency of the first functional layer 140 is low. In addition, when the particle size of the first nanoparticles is large, the film-forming property of the first nanoparticles is relatively poor. Therefore, by setting the particle size of the first nanoparticles to 4 nm to 6 nm, the electron transport efficiency of the first functional layer 140 and the light-emitting efficiency of the light-emitting device 100 can be high, the film-forming property of the first nanoparticles can be good, and a dense first functional layer 140 can be formed. In addition, the surface defect density of the first nanoparticles can be reduced, the first functional layer 140 is not easily affected by the positive aging effect, the positive aging problem of the light-emitting device 100 can be alleviated, and thus the process step of accelerating the positive aging in the preparation process of the display panel 200 can be omitted, the preparation process of the display panel 200 can be simplified, and the controllability and repeatability of the preparation process of the display panel 200 can be improved.

[0143] In some embodiments, as shown in FIGS. 2 and 3, the material of the first functional layer 140 further includes second nanoparticles; the particle size of the second nanoparticles is smaller than the particle size of the first nanoparticles.

[0144] Exemplarily, the particle size of the second nanoparticles can be 1.0 nm, 2.0 nm, 2.5 nm, 3.0 nm, 3.2 nm, 4.0 nm, 5.0 nm, or 5.5 nm, etc.

[0145] Exemplarily, the particle size of the first nanoparticles and / or the particle size of the second nanoparticles can be measured by a transmission electron microscope (TEM).

[0146] It can be understood that when the particle size of the second nanoparticles is smaller than the particle size of the first nanoparticles, the electron mobility of the second nanoparticles is greater than the electron mobility of the first nanoparticles, and the film-forming property of the second nanoparticles is better than the film-forming property of the first nanoparticles. Therefore, by setting that the material of the first functional layer 140 further includes the second nanoparticles, the electron transport efficiency of the first functional layer 140 can be improved, and the film-forming property of the material of the first functional layer 140 can be improved, and the density and uniformity of the first functional layer 140 can be improved.

[0147] In some embodiments, as shown in FIG. 2 and FIG. 3, the material of the first functional layer 140 includes third nanoparticles, the third nanoparticles including a first metal oxide material and a first ligand material ligated to the first metal oxide material; the mass ratio of the first ligand material in the third nanoparticles is 16% to 25%.

[0148] For example, the mass ratio of the first ligand material in the third nanoparticles can be 16%, 18%, 20%, 22%, 23% or 25%, etc.

[0149] For example, the mass ratio of the first ligand material in the third nanoparticles can be obtained by measuring the mass of the first ligand material and the mass of the third nanoparticles respectively, or it can also be obtained by measuring the content of the characteristic element or characteristic substituent in the first ligand material and the content of the characteristic element in the third nanoparticles; of course, other ways can also be used, which are not limited here.

[0150] In some examples, thermogravimetric analysis (TGA) can be used to measure the mass ratio of the first ligand material in the third nanoparticles.

[0151] It can be understood that the first ligand material can passivate the surface defects of the third nanoparticles, when the mass ratio of the first ligand material in the third nanoparticles is small, the passivation degree of the surface defects of the third nanoparticles is low, the surface defect density of the third nanoparticles is high, and the positive aging phenomenon is easy to occur. When the mass ratio of the first ligand material in the third nanoparticles is large, it may affect the electron transport efficiency of the first functional layer 140, and the conductivity is low. Therefore, by setting the mass ratio of the first ligand material in the third nanoparticles to be 16% to 25%, the passivation degree of the surface defects of the third nanoparticles can be high on the basis of high electron transport efficiency of the first functional layer 140 and high luminous efficiency of the light-emitting device 100, the surface defect density of the third nanoparticles can be reduced, the probability of the first functional layer 140 producing the positive aging phenomenon is low, the positive aging problem of the light-emitting device 100 can be alleviated, thus the accelerated positive aging process step in the preparation process of the display panel 200 can be omitted, the preparation process of the display panel 200 can be simplified, and the controllability and repeatability of the preparation process of the display panel 200 are improved.

[0152] In some embodiments, as shown in FIG. 2 and FIG. 3, the material of the first functional layer 140 further includes fourth nanoparticles, the fourth nanoparticles including a second metal oxide material and a second ligand material ligated to the second metal oxide material; the mass ratio of the second ligand material in the fourth nanoparticles is less than the mass ratio of the first ligand material in the third nanoparticles.

[0153] Exemplarily, the mass ratio of the second ligand material in the fourth nanoparticles can be 1%, 3%, 7%, 10%, 11%, 12%, 12.5%, 13%, 14%, or 15%, etc.

[0154] Here, the description about the calculation or measurement method of the mass ratio of the second ligand material in the fourth nanoparticles can refer to the foregoing exemplary description about the mass ratio of the first ligand material in the third nanoparticles, which will not be repeated here.

[0155] It can be understood that, in the case that the mass ratio of the second ligand material in the fourth nanoparticles is less than the mass ratio of the first ligand material in the third nanoparticles, the conductivity of the fourth nanoparticles is superior to the conductivity of the third nanoparticles, and the electron transport efficiency of the fourth nanoparticles is greater than the electron transport efficiency of the third nanoparticles. Therefore, by further including the fourth nanoparticles in the material of the first functional layer 140, the electron transport efficiency and the conductivity of the first functional layer 140 can be improved, and the efficiency of the light-emitting device 100 can be improved.

[0156] Here, the type of the first ligand material and / or the second ligand material is not limited here, as long as it can meet the requirement of passivating the surface defects of the third nanoparticles and / or the fourth nanoparticles.

[0157] In some embodiments, the first ligand material includes ethanolamine.

[0158] In some embodiments, in the case that the material of the first functional layer 140 includes the fourth nanoparticles, the second ligand material includes ethanolamine.

[0159] It can be understood that ethanolamine contains amine group substituents that can be arranged on the surface of the third nanoparticles and / or the fourth nanoparticles, and when the ethanolamine is arranged on the surface of the third nanoparticles and / or the fourth nanoparticles, the amine group substituents contained in the ethanolamine can be combined with the surface defects (such as -OH or oxygen vacancies) of the third nanoparticles and / or the fourth nanoparticles, so as to achieve the purpose of passivating the surface defects of the third nanoparticles and / or the fourth nanoparticles.

[0160] Here, as one possible existence mode, -OH can be a free hydroxyl group on the surface of the third nanoparticles and / or the fourth nanoparticles, and as another possible existence mode, -OH can also be obtained by occupying the vacancy of the oxygen atom with a hydrogen atom; as still another possible existence mode, the hydrogen atom can also be located between the oxygen atom and other atoms X (for example: zinc Zn) of the third nanoparticles and / or the fourth nanoparticles, forming the form of X-O-H (for example: Zn-O-H). That is, as to the form of the surface defect -OH that can exist in the third nanoparticles and / or the fourth nanoparticles, there is no limitation here.

[0161] In some embodiments, as shown in FIG. 4, the first functional layer 140 includes a first sub-layer 14a, a second sub-layer 14b, and a third sub-layer 14c stacked along a first direction X. The second sub-layer 14b is located between the first sub-layer 14a and the third sub-layer 14c; the first direction X is the arrangement direction of the anode 110 and the cathode 120.

[0162] In some examples, as shown in FIG. 4, the first sub-layer 14a, the second sub-layer 14b, and the third sub-layer 14c are arranged in sequence along a direction close to the cathode 120; at this time, the third sub-layer 14c can or can not be in contact with the cathode 120; the first sub-layer 14a can or can not be in contact with the light-emitting layer 130.

[0163] In other examples, the first sub-layer 14a, the second sub-layer 14b, and the third sub-layer 14c are arranged in sequence along a direction away from the cathode 120; at this time, the first sub-layer 14a can or can not be in contact with the cathode 120; the third sub-layer 14c can or can not be in contact with the light-emitting layer 130.

[0164] In some embodiments, as shown in FIG. 4, the electron mobility of the material of the second sub-layer 14b is greater than or equal to the electron mobility of the material of the first sub-layer 14a.

[0165] In some embodiments, the electron mobility of the material of the second sub-layer 14b is greater than or equal to the electron mobility of the material of the third sub-layer 14c.

[0166] It should be understood that when the electron mobility of the material of the second sub-layer 14b is greater than or equal to the electron mobility of the material of the first sub-layer 14a, the material property of the second sub-layer 14b is more active relative to the material property of the first sub-layer 14a, and is more likely to affect the material property (for example, the light-emitting efficiency of the light-emitting layer 130) of the material of the adjacent film layer (for example, the light-emitting layer 130 or the cathode 120).

[0167] As described above, when the electron mobility of the material of the second sub-layer 14b is greater than or equal to the electron mobility of the material of the third sub-layer 14c, the material of the second sub-layer 14b is more active than the material of the third sub-layer 14c, and is more likely to affect the properties (e.g., the light-emitting efficiency of the light-emitting layer 130) of the material of the adjacent film layer (e.g., the light-emitting layer 130 or the cathode 120).

[0168] It can be understood that, in the case where the first sub-layer 14a, the second sub-layer 14b, and the third sub-layer 14c are stacked along the first direction X, the second sub-layer 14b is arranged at the middle portion of the first functional layer 140, that is, the second sub-layer 14b does not contact the film layer (e.g., the light-emitting layer 130 or the cathode 120) adjacent to the first functional layer 140, so that the influence of the material of the second sub-layer 14b on the properties of the material of the adjacent film layer can be reduced, the properties of the material of the adjacent film layer can meet the set requirements, and the performance of the light-emitting device 100 can be improved.

[0169] In some embodiments, as shown in FIG. 4, in the case where the material of the first functional layer 140 includes first nanoparticles and second nanoparticles, the first nanoparticles are arranged in the first sub-layer 14a and / or the third sub-layer 14c; and the second nanoparticles are arranged in the second sub-layer 14b.

[0170] For example, the first nanoparticles are arranged in the first sub-layer 14a and the third sub-layer 14c.

[0171] It can be understood that the surface defect density of the first nanoparticles is lower than the surface defect density of the second nanoparticles, and when the first nanoparticles are arranged in the first sub-layer 14a and / or the third sub-layer 14c, the first nanoparticles can be arranged in the portion of the first functional layer 140 that contacts the adjacent film layer; and when the second nanoparticles are arranged in the second sub-layer 14b, the second nanoparticles can be arranged in the middle portion of the first functional layer 140, that is, in the portion of the first functional layer 140 that does not contact the adjacent film layer; in this way, the surface defect density of the nanoparticles in the portion of the first functional layer 140 that contacts the adjacent film layer can be reduced, and the surface defect density of the nanoparticles in the portion of the first functional layer 140 that does not contact the adjacent film layer can be increased, so that the influence of the material of the first functional layer 140 on the properties of the material of the adjacent film layer can be reduced on the basis of improving the high conductivity of the first functional layer 140, the properties of the material of the adjacent film layer can meet the set requirements, and the performance of the light-emitting device 100 can be improved.

[0172] In some embodiments, the particle size of the first nanoparticles is 5 nm to 6 nm, and the particle size of the second nanoparticles is 3 nm to 4 nm.

[0173] In some examples, as shown in FIG. 4, the first nanoparticles are arranged in the first sub-layer 14a and / or the third sub-layer 14c; and the second nanoparticles are arranged in the second sub-layer 14b. The first nanoparticles have a particle size of 5 nm to 6 nm, for example, 5.0 nm, 5.2 nm, 5.5 nm, 5.7 nm, 5.8 nm, or 6.0 nm; and the second nanoparticles have a particle size of 3 nm to 4 nm, for example, 3.0 nm, 3.2 nm, 3.4 nm, 3.7 nm, 3.9 nm, or 4.0 nm. It should be noted that, in this case, the particle size of the first nanoparticles arranged in the first sub-layer 14a and the particle size of the first nanoparticles arranged in the third sub-layer 14c can be the same or different, which is not limited herein.

[0174] It can be understood that, by the above arrangement, on the one hand, the particle size of the first nanoparticles can be large, and the surface defect density of the first nanoparticles can be low, so that the positive aging problem of the light-emitting device 100 can be alleviated; on the other hand, the particle size of the second nanoparticles can be small, and the effect of improving the conductivity of the first functional layer 140 by the second nanoparticles can be improved; in this way, the conductivity of the first functional layer 140 can be improved, and at the same time, the process step of accelerating positive aging in the preparation process of the display panel 200 can be omitted, so that the controllability and repeatability of the preparation process of the display panel 200 can be improved.

[0175] Furthermore, in the case that the first nanoparticles are arranged in the first sub-layer 14a and / or the third sub-layer 14c; and the second nanoparticles are arranged in the second sub-layer 14b, by the above arrangement, the particle size of the first nanoparticles can be large, and the surface defect density of the first nanoparticles can be low, so that the influence of the material of the first functional layer 140 on the properties of the material of the adjacent film layer can be reduced.

[0176] In some examples, as shown in FIG. 4, the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the material of the second sub-layer 14b is greater than or equal to the absolute value of the lowest unoccupied molecular orbital energy level of the material of the first sub-layer 14a.

[0177] For example, in the case that the first nanoparticles are arranged in the first sub-layer 14a; and the second nanoparticles are arranged in the second sub-layer 14b, the absolute value of the LUMO energy level of the second nanoparticles is greater than or equal to the absolute value of the LUMO energy level of the first nanoparticles.

[0178] In some examples, as shown in FIG. 4, the absolute value of the lowest unoccupied molecular orbital energy level of the material of the second sub-layer 14b is greater than or equal to the absolute value of the lowest unoccupied molecular orbital energy level of the material of the third sub-layer 14c.

[0179] Exemplarily, in the case that the first nanoparticles are arranged in the third sublayer 14c and the second nanoparticles are arranged in the second sublayer 14b, the absolute value of the LUMO energy level of the second nanoparticles is greater than or equal to the absolute value of the LUMO energy level of the first nanoparticles.

[0180] It should be understood that, when the absolute value of the LUMO energy level of the material of the second sublayer 14b is greater than or equal to the absolute value of the LUMO energy level of the material of the first sublayer 14a, the LUMO energy level of the material of the second sublayer 14b is shallower than the LUMO energy level of the material of the first sublayer 14a. When the absolute value of the LUMO energy level of the material of the second sublayer 14b is greater than or equal to the absolute value of the LUMO energy level of the material of the third sublayer 14c, the LUMO energy level of the material of the second sublayer 14b is shallower than the LUMO energy level of the material of the third sublayer 14c.

[0181] It can be understood that, by the above arrangement, a stepped energy level structure can be formed between the second sublayer 14b and the first sublayer 14a and / or between the second sublayer 14b and the third sublayer 14c, that is, a stepped energy level structure can be formed in the first functional layer 140, so that the electron transport effect can be improved and the efficiency of the light-emitting device can be improved.

[0182] In some embodiments, as shown in FIG. 4, in the case that the material of the first functional layer 140 includes third nanoparticles and fourth nanoparticles, the third nanoparticles are arranged in the first sublayer 14a and / or the third sublayer 14c, and the fourth nanoparticles are arranged in the second sublayer 14b.

[0183] Exemplarily, the third nanoparticles are arranged in the first sublayer 14a and the third sublayer 14c.

[0184] Similarly, the surface defect density of the third nanoparticles is lower than the surface defect density of the fourth nanoparticles. By such an arrangement, the surface defect density of the nanoparticles in the part of the first functional layer 140 that is in contact with the adjacent film layer can be low, and the surface defect density of the nanoparticles in the part of the first functional layer 140 that is not in contact with the adjacent film layer can be high. In this way, on the basis of improving the high conductivity of the first functional layer 140, the influence of the material of the first functional layer 140 on the properties of the material of the adjacent film layer can be reduced, so that the properties of the material of the adjacent film layer can meet the set requirements, and the performance of the light-emitting device 100 can be improved.

[0185] In some embodiments, as shown in FIG. 4, the mass fraction of the second ligand material in the fourth nanoparticles is 10% to 15%.

[0186] It can be understood that, through the above setting, firstly, the mass fraction of the first ligand material in the third nanoparticles can be high, so that the surface defect density of the third nanoparticles is low, and the positive aging problem of the light-emitting device 100 can be alleviated; secondly, the mass fraction of the second ligand material in the fourth nanoparticles can be low, so that the effect of improving the conductivity of the first functional layer 140 by the fourth nanoparticles can be improved; in this way, the conductivity of the first functional layer 140 can be improved, and at the same time, the process step of accelerating positive aging in the preparation process of the display panel 200 can be omitted, so that the controllability and repeatability of the preparation process of the display panel 200 are improved.

[0187] Furthermore, in the case that the third nanoparticles are arranged in the first sub-layer 14a and / or the third sub-layer 14c, and the fourth nanoparticles are arranged in the second sub-layer 14b, through the above setting, the influence of the material of the first functional layer 140 on the properties of the material of the adjacent film layer can be reduced.

[0188] In some embodiments, the first nanoparticles include one or any combination of zinc oxide (ZnO) and doped zinc oxide. The doped zinc oxide is zinc oxide containing a doping element.

[0189] In some embodiments, in the case that the material of the first functional layer includes the second nanoparticles, the second nanoparticles include one or any combination of zinc oxide (ZnO) and doped zinc oxide. The doped zinc oxide is zinc oxide containing a doping element.

[0190] In some embodiments, in the case that the material of the first functional layer includes the third nanoparticles, the first metal oxide material includes one or any combination of zinc oxide (ZnO) and doped zinc oxide. The doped zinc oxide is zinc oxide containing a doping element.

[0191] In some embodiments, in the case that the material of the first functional layer includes the fourth nanoparticles, the second metal oxide material includes one or any combination of zinc oxide (ZnO) and doped zinc oxide. The doped zinc oxide is zinc oxide containing a doping element.

[0192] Here, the doped zinc oxide is zinc oxide containing a doping element, which can be understood as a product obtained by adding a doping element in the preparation process of zinc oxide, for example, magnesium (Mg) doped (for example: magnesium ion doped) zinc oxide (ZnO) can be represented as ZnMgO.

[0193] In some embodiments, as shown in FIG. 2 and FIG. 3, in the case that one or more of the first nanoparticles, the second nanoparticles, the first metal oxide material, and the second metal oxide material comprises doped zinc oxide, the doping element comprises one or a combination of any number of lithium (Li), magnesium (Mg), aluminum (Al), gallium (Ga), yttrium (Y), and copper (Cu).

[0194] In some examples, the doping element contained in the doped zinc oxide is multiple, for example, magnesium (Mg) and aluminum (Al) co-doped zinc oxide (ZnO) can be represented as ZnMgAlO.

[0195] It should be understood that in the case that the doping element can be any one of the multiple doping elements, or a combination of any number of the multiple doping elements, the type of the doped zinc oxide can be multiple. Therefore, the first nanoparticles comprising one or a combination of any number of zinc oxide (ZnO) and doped zinc oxide means that the first nanoparticles can comprise one material, which can be zinc oxide or doped zinc oxide, or the first nanoparticles can comprise multiple materials, which can be zinc oxide and a combination of any one or any number of doped zinc oxide, or a combination of any number of doped zinc oxide. Here, the understanding of the second nanoparticles, the first metal oxide material, or the second metal oxide material comprising one or a combination of any number of zinc oxide and doped zinc oxide can be referred to the above description, which will not be repeated here.

[0196] It can be understood that the zinc oxide material has the advantages of large energy band gap and exciton binding energy, high transparency, and excellent room temperature electron transport performance, and the doped zinc oxide can take into account the above advantages of zinc oxide, and the doping element can be used to adjust the energy level, electron transport efficiency, and other properties of the doped zinc oxide; therefore, through the above setting, the electron transport performance of the first functional layer 140 can be improved, and the light transmittance of the first functional layer 140 is good, which is beneficial to improve the light emitting efficiency of the light emitting device 100.

[0197] Moreover, when the doping element comprises one or a combination of any number of lithium (Li), magnesium (Mg), aluminum (Al), gallium (Ga), yttrium (Y), and copper (Cu), the feasibility of the doping element adjusting the properties (for example: LUMO energy level) of the zinc oxide can be improved; and the above doping elements have the advantages of being easy to obtain and having good compatibility with zinc oxide.

[0198] In some embodiments, in the case that one or more of the first nanoparticles, the second nanoparticles, the first metal oxide material, and the second metal oxide material comprises doped zinc oxide, the mass percentage of the doping element in the doped zinc oxide is 1% to 20%.

[0199] It should be noted that, in the case of a plurality of doping elements, the mass percentage of the doping elements in the doped zinc oxide is equal to the sum of the mass percentages of each doping element in the doped zinc oxide. For example, in the case of magnesium-aluminum co-doped doped zinc oxide ZnMgAlO, the mass percentage of magnesium in the doped zinc oxide is 4%, and the mass percentage of aluminum in the doped zinc oxide is 5%, so the mass percentage of the doping elements in the doped zinc oxide is 9%.

[0200] Exemplarily, in the case where one or more of the first nanoparticles, the second nanoparticles, the first metal oxide material, and the second metal oxide material comprises doped zinc oxide, the mass percentage of the doping elements in the doped zinc oxide can be 1%, 3%, 5%, 7%, 9%, 12%, 15%, or 20%, etc.

[0201] It can be understood that, by the above setting, the mass percentage of the doping elements in the doped zinc oxide can be within a suitable range, which can make the doped zinc oxide have the advantages of a large energy band gap and exciton binding energy of zinc oxide, high transparency, and excellent room-temperature electron transport performance, and can utilize the doping elements to regulate the energy level and electron transport efficiency of the doped zinc oxide; in this way, the electron transport performance of the first functional layer 140 can be improved, and the first functional layer 140 has good light transmittance, which is beneficial to improving the light-emitting efficiency of the light-emitting device 100.

[0202] In some embodiments, as shown in FIG. 4, in the case where the first nanoparticles are arranged in the first sub-layer 14a and / or the third sub-layer 14c and the first nanoparticles comprise zinc oxide, the highest occupied molecular orbital energy level of the first nanoparticles is -7.5 eV to -8.0 eV.

[0203] Exemplarily, in the case where the first nanoparticles are arranged in the first sub-layer 14a and / or the third sub-layer 14c and the first nanoparticles comprise zinc oxide, the highest occupied molecular orbital energy level of the first nanoparticles can be -7.5 eV, -7.6 eV, -7.65 eV, -7.7 eV, -7.8 eV, -7.9 eV, or -8.0 eV, etc.

[0204] In some embodiments, as shown in FIG. 4, in the case where the first nanoparticles are arranged in the first sub-layer 14a and / or the third sub-layer 14c and the first nanoparticles comprise zinc oxide, the lowest unoccupied molecular orbital energy level of the first nanoparticles is -3.8 eV to -4.0 eV.

[0205] Exemplarily, in the case that the first nanoparticles are disposed in the first sub-layer 14a and / or the third sub-layer 14c and the first nanoparticles comprise zinc oxide, the lowest unoccupied molecular orbital energy level of the first nanoparticles can be -3.80 eV, -3.85 eV, -3.90 eV, -3.95 eV, -3.97 eV or -4.00 eV, etc.

[0206] It can be understood that, by the above arrangement, the height of the potential barrier that needs to be overcome by the carriers (e.g., electrons) when transitioning between the first functional layer 140 and the light-emitting layer 130 and / or between the first functional layer 140 and the cathode 120 can be reduced, and the light-emitting efficiency of the light-emitting device 100 can be improved.

[0207] In some embodiments, as shown in FIG. 4, in the case that the material of the first functional layer 140 further comprises second nanoparticles disposed in the second sub-layer 14b and the second nanoparticles comprise zinc oxide, the highest occupied molecular orbital energy level of the second nanoparticles is -7.5 eV to -8.0 eV.

[0208] Exemplarily, in the case that the material of the first functional layer 140 further comprises second nanoparticles disposed in the second sub-layer 14b and the second nanoparticles comprise zinc oxide, the highest occupied molecular orbital energy level of the second nanoparticles can be -7.5 eV, -7.6 eV, -7.70 eV, -7.76 eV, -7.8 eV, -7.9 eV or -8.0 eV, etc.

[0209] In some embodiments, as shown in FIG. 4, in the case that the material of the first functional layer 140 further comprises second nanoparticles disposed in the second sub-layer 14b and the second nanoparticles comprise zinc oxide, the lowest unoccupied molecular orbital energy level of the second nanoparticles is -4.0 eV to -4.3 eV.

[0210] Exemplarily, in the case that the material of the first functional layer 140 further comprises second nanoparticles disposed in the second sub-layer 14b and the second nanoparticles comprise zinc oxide, the lowest unoccupied molecular orbital energy level of the second nanoparticles can be -4.00 eV, -4.05 eV, -4.10 eV, -4.15 eV, -4.20 eV, -4.26 eV or -4.30 eV, etc.

[0211] It can be understood that, by the above arrangement, a stepped energy level structure can be formed between the second sub-layer 14b and the first sub-layer 14a and / or between the second sub-layer 14b and the third sub-layer 14c, that is, a stepped energy level structure can be formed in the first functional layer 140, and thus the electron transport effect can be improved and the efficiency of the light-emitting device 100 can be improved.

[0212] The above is an exemplary introduction to some embodiments of the first functional layer 140 including nanoparticles. The following will exemplarily introduce some embodiments of the first functional layer 140 including an electron transport thin film.

[0213] In some embodiments, as shown in FIG. 5, the first functional layer 140 includes a first electron transport thin film 14A.

[0214] Here, the first electron transport thin film 14A can be understood as a thin film formed by a certain process (for example, a sputtering process or a solution gel process). In some examples, the forming process of the first functional layer 140 including nanoparticles can be different from the forming process of the first functional layer 140 including the first electron transport thin film 14A. Moreover, the first electron transport thin film 14A does not include nanoparticles.

[0215] It can be understood that the first electron transport thin film 14A is in the form of a thin film, so that the specific surface area of the material of the first electron transport thin film 14A is relatively smaller than the specific surface area of the nanoparticles, and the surface defect density of the material of the first electron transport thin film 14A is relatively lower than the surface defect density of the nanoparticles. In this way, the surface defects of the material of the first functional layer 140 can be reduced, so that the first functional layer 140 is not easily affected by the positive aging effect, and the problem of positive aging of the light-emitting device 100 can be alleviated. Thus, the process step of accelerating positive aging in the preparation process of the display panel 200 can be omitted, and the controllability and repeatability of the preparation process of the display panel 200 can be improved.

[0216] In some embodiments, as shown in FIG. 2, FIG. 4, FIG. 25 and FIG. 26, the plurality of light-emitting devices 100 in the display panel 200 are upright light-emitting devices, and the light-emitting layer 130 of each of the plurality of light-emitting devices 100 is a quantum dot light-emitting layer. Moreover, each of the plurality of light-emitting devices 100 further includes a hole transport layer 160 located between the anode 110 and the light-emitting layer 130; in some examples, each of the plurality of light-emitting devices 100 further includes a hole injection layer 150 located between the hole transport layer 160 and the light-emitting layer 130.

[0217] As shown in FIG. 6, an exemplary preparation process of the plurality of light-emitting devices 100 in the display panel 200 is introduced. Please refer to the last diagram in FIG. 6 (i.e., the diagram corresponding to step M7), which shows that the display panel 200 includes a substrate 210, a pixel defining layer 221 disposed on the substrate 210, and a plurality of light-emitting devices 100 (for example, including a first light-emitting device 101, a second light-emitting device 102, and a third light-emitting device 103). The pixel defining layer 221 has a plurality of openings Q, and the plurality of light-emitting devices 100 can be disposed one-to-one corresponding to the plurality of openings Q.

[0218] M1: Forming a pixel defining layer 221 on one side of the substrate 210, the pixel defining layer 221 comprising a plurality of openings Q.

[0219] M2: Forming the anode 110 in the plurality of openings Q.

[0220] M3: Forming the hole injection layer 150 on the side of the anode 110 away from the substrate 210.

[0221] Exemplarily, the process of forming the hole injection layer 150 can be an inkjet printing process.

[0222] M4: Forming the hole transport layer 160 on the side of the hole injection layer 150 away from the anode 110.

[0223] Exemplarily, the process of forming the hole transport layer 160 can be an inkjet printing process.

[0224] M5: Forming the light emitting layer 131 of the first light emitting device 101 in the opening Q corresponding to the first light emitting device 101, forming the light emitting layer 132 of the second light emitting device 102 in the opening Q corresponding to the second light emitting device 102, and forming the light emitting layer 133 of the third light emitting device 103 in the opening Q corresponding to the third light emitting device 103, so that in each opening Q, the light emitting layer 130 is located on the side of the hole transport layer 160 away from the hole injection layer 150.

[0225] M6: Forming the first functional layer 140 on the side of the light emitting layer 130 of the plurality of first light emitting devices 101, the plurality of second light emitting devices 102, and the plurality of third light emitting devices 103 away from the hole transport layer 160.

[0226] M7: Forming the cathode 120 on the side of the first functional layer 140 away from the light emitting layer 130.

[0227] However, in the actual process of preparing the plurality of light emitting devices 100 in the display panel 200, as shown in FIG. 6, the material for forming part of the film layers (for example, the ink for forming the hole injection layer 150, and / or the ink for forming the hole transport layer 160) will climb on the pixel defining layer 221, and even climb to the top platform area of the pixel defining layer 221, which will cause unevenness of these film layers, and when both the ink for forming the hole injection layer 150 and the ink for forming the hole transport layer 160 have the problem of climbing, the unevenness of these film layers will increase layer by layer; secondly, it will affect the uniformity of the morphology and thickness of the subsequently formed film layers (for example: the light emitting layer 130 and / or the first functional layer 140), which will adversely affect the performance and uniformity of the final light emitting device 100, and is not conducive to the mass production of quantum dot light emitting devices. Moreover, when the above display panel 200 is a high-resolution panel, the above problems are more pronounced.

[0228] Based on this, in some embodiments, as shown in FIG. 5, the light-emitting device 100 is arranged on the substrate 210; the cathode 120 is closer to the substrate 210 than the anode 110.

[0229] It should be understood that when the cathode 120 is closer to the substrate 210 than the anode 110, the light-emitting device 100 is an inverted light-emitting device, in which case, the preparation method of the light-emitting device 100 can include the following steps arranged in sequence: forming the cathode 120, forming the first functional layer 140, forming the light-emitting layer 130, forming the hole transport layer 160, forming the hole injection layer 150, and forming the anode 110. In this way, the first functional layer 140 can be formed before the light-emitting layer 130.

[0230] It can be understood that when the first functional layer 140 is formed before the light-emitting layer 130, compared with the case where the light-emitting layer 130 is formed before the hole injection layer 150 and the hole transport layer 160, the uniformity of the light-emitting layer 130 and the light-emitting device 100 as a whole can be improved. Moreover, when the first functional layer 140 includes the first electron transport thin film 14A, the thickness uniformity of the first electron transport thin film 14A is high, the thickness uniformity of the first functional layer 140 is high, and thus, the uniformity of the light-emitting layer 130 and the light-emitting device 100 as a whole can also be improved, which is conducive to mass production of the QLED display panel and enables the light-emitting device 100 to be applied to high-resolution QLED display panels.

[0231] In some implementations, as shown in FIGS. 5 and 27, the first functional layer 140 including the first electron transport thin film 14A (the material of the first electron transport thin film 14A is, for example, zinc oxide) has a large electron mobility and a deep LUMO level, so that the LUMO level of the first functional layer 140 is close to the LUMO level of the cathode 120 (the material of the cathode 120 is, for example, ITO), but the LUMO level of the first functional layer 140 is quite different from the LUMO level of the light-emitting layer 130, which makes it difficult for electrons to be injected from the first electron transport thin film 14A to the light-emitting layer 130, and even causes the phenomenon of electron leakage, resulting in low light-emitting efficiency and low brightness of the light-emitting device 100.

[0232] Based on the above, in some embodiments, as shown in FIG. 5, the first functional layer 140 further includes a second electron transport thin film 14B. The first electron transport thin film 14A is closer to the cathode 120 than the second electron transport thin film 14B. The absolute value of the lowest unoccupied molecular orbital energy level of the material of the second electron transport thin film 14B is smaller than the absolute value of the lowest unoccupied molecular orbital energy level of the material of the first electron transport thin film 14A, and is larger than the absolute value of the lowest unoccupied molecular orbital energy level of the material of the light-emitting layer 130.

[0233] It should be understood that when the absolute value of the LUMO level of the material of the second electron transport thin film 14B is less than the absolute value of the LUMO level of the material of the first electron transport thin film 14A and greater than the absolute value of the LUMO level of the material of the light-emitting layer 130, the LUMO level of the material of the second electron transport thin film 14B is between the LUMO level of the material of the first electron transport thin film 14A and the LUMO level of the material of the light-emitting layer 130.

[0234] It can be understood that through the above arrangement, on the one hand, a stepped energy level structure (as shown in FIG. 28) can be formed between the first functional layer 140 and the light-emitting layer 130, which can alleviate the problem of mismatching of the energy level of the electron transport layer in the light-emitting device 100 (for example, an inverted QLED light-emitting device), improve the electron injection effect, and improve the electron transport efficiency of the light-emitting device 100; on the other hand, the electron utilization rate of the light-emitting device 100 can be improved, and the luminous efficiency of the light-emitting device 100 can be improved; and on the other hand, the turn-on voltage of the light-emitting device 100 can be reduced, and the brightness of the light-emitting device 100 can be improved.

[0235] In some embodiments, as shown in FIG. 5, the lowest unoccupied molecular orbital energy level of the material of the first electron transport thin film 14A is -4.7 eV to -4.2 eV.

[0236] For example, the lowest unoccupied molecular orbital energy level of the material of the first electron transport thin film 14A can be -4.7 eV, -4.6 eV, -4.5 eV, -4.56 eV, -4.4 eV, -4.3 eV, or -4.2 eV.

[0237] It can be understood that through such an arrangement, electrons can be more easily injected from the cathode 120 to the first electron transport thin film 14A, the electron injection effect of the light-emitting device 100 can be improved, the efficiency and brightness of the light-emitting device 100 can be improved, and the turn-on voltage of the light-emitting device 100 can be reduced.

[0238] In some embodiments, as shown in FIG. 5, the lowest unoccupied molecular orbital energy level of the material of the second electron transport thin film 14B is -4.2 eV to -3.8 eV.

[0239] For example, the lowest unoccupied molecular orbital energy level of the material of the second electron transport thin film 14B can be -4.2 eV, -4.1 eV, -4.04 eV, -4.0 eV, -3.9 eV, -3.85 eV, or -3.8 eV.

[0240] It can be understood that, by being arranged in this way, the electrons can be more easily injected from the first electron transport thin film 14A to the second electron transport thin film 14B, and the electrons can be more easily injected from the second electron transport thin film 14B to the light-emitting layer 130, so that the height of the potential barrier that the electrons need to overcome when being transported from the first functional layer 140 to the light-emitting layer 130 can be reduced, the electron transport effect of the light-emitting device 100 can be improved, the risk of electron leakage can be reduced, and the efficiency and brightness of the light-emitting device 100 can be improved, while the turn-on voltage of the light-emitting device 100 can be reduced.

[0241] In some embodiments, as shown in FIG. 5, the ratio D1 / D2 between the size D1 of the first electron transport thin film 14A along the first direction X and the size D2 of the second electron transport thin film 14B along the first direction X ranges from 1:1 to 3:1, and the first direction X is the arrangement direction of the anode 110 and the cathode 120. That is, 1:1≤D1 / D2≤3:1.

[0242] Exemplarily, the ratio D1 / D2 between the size D1 of the first electron transport thin film 14A along the first direction X and the size D2 of the second electron transport thin film 14B along the first direction X can be 1:1, 1.2:1, 1.5:1, 1.8:1, 2.0:1, 2.3:1, 2.5:1, 2.7:1 or 3:1.

[0243] It can be understood that when the ratio D1 / D2 between the size D1 of the first electron transport thin film 14A along the first direction X and the size D2 of the second electron transport thin film 14B along the first direction X is large (for example, greater than 3:1), the first electron transport thin film 14A is relatively thick relative to the second electron transport thin film 14B, and the thickness difference between the two is large, so that the thickness of the second electron transport thin film 14B is small, which can affect the electron transport effect when the electrons are transported from the first functional layer 140 to the light-emitting layer 130; when the ratio D1 / D2 between the size D1 of the first electron transport thin film 14A along the first direction X and the size D2 of the second electron transport thin film 14B along the first direction X is small (for example, less than 1:1), the first electron transport thin film 14A is relatively thin relative to the second electron transport thin film 14B, so that the thickness of the first electron transport thin film 14A is small, which can affect the electron injection effect when the electrons are injected from the cathode 120 to the first functional layer 140; therefore, by setting the ratio D1 / D2 between the size D1 of the first electron transport thin film 14A along the first direction X and the size D2 of the second electron transport thin film 14B along the first direction X in the range of 1:1 to 3:1, the electron transport effect when the electrons are transported from the first functional layer 140 to the light-emitting layer 130 can be improved, and at the same time, the electron injection effect when the electrons are injected from the cathode 120 to the first functional layer 140 can be improved, so that the electron transport effect of the light-emitting device 100 can be improved, the risk of leakage can be reduced, the efficiency and brightness of the light-emitting device 100 can be improved, and at the same time, the turn-on voltage of the light-emitting device 100 can be reduced.

[0244] In some embodiments, as shown in FIG. 5, the material of the first electron transport thin film 14A includes zinc oxide. The material of the second electron transport thin film 14B includes doped zinc oxide, and the doped zinc oxide is zinc oxide containing a doping element.

[0245] Here, for the understanding of the doped zinc oxide, reference can be made to the foregoing exemplary description of the doped zinc oxide, which will not be repeated here.

[0246] It can be understood that by such setting, the LUMO level of the material of the first electron transport thin film 14A can be within a suitable range (for example: -4.7 eV to -4.2 eV), so that the electrons can be more easily injected from the cathode 120 to the first electron transport thin film 14A, and at the same time, the LUMO level of the material of the second electron transport thin film 14B can be within a suitable range (for example: -4.2 eV to -3.8 eV), so that the height of the potential barrier that needs to be overcome when the electrons are transported from the first functional layer 140 to the light-emitting layer 130 can be reduced; in this way, the electron injection effect and the electron transport effect of the light-emitting device 100 can be improved, the risk of electron leakage can be reduced, the efficiency and brightness of the light-emitting device 100 can be improved, and at the same time, the turn-on voltage of the light-emitting device 100 can be reduced.

[0247] In some embodiments, as shown in FIG. 5, in the case where the material of the second electron transport thin film 14B comprises doped zinc oxide, the mass percentage of the doping element in the doped zinc oxide is greater than 0% and less than or equal to 10%.

[0248] For example, in the case where the material of the second electron transport thin film 14B comprises doped zinc oxide, the mass percentage of the doping element in the doped zinc oxide can be 0.5%, 2%, 4%, 4.5%, 5%, 5.5%, 6%, 7%, 8% or 10%, etc.

[0249] It can be understood that when the mass percentage of the doping element in the doped zinc oxide in the material of the second electron transport thin film 14B is relatively large (for example, greater than 10%), the LUMO energy level of the material of the second electron transport thin film 14B is relatively high (for example, greater than -3.8 eV), the potential barrier between the first electron transport thin film 14A and the second electron transport thin film 14B is increased, and the injection of electrons from the first electron transport thin film 14A to the second electron transport thin film 14B is difficult. Therefore, by the above arrangement, the LUMO energy level of the material of the second electron transport thin film 14B can be within a suitable range (for example, -4.2 eV to -3.8 eV), the potential barrier for the injection of electrons from the first electron transport thin film 14A to the second electron transport thin film 14B can be reduced, and thus the electron injection effect and the electron transport effect of the light-emitting device 100 can be improved, the risk of leakage can be reduced, the efficiency and brightness of the light-emitting device 100 can be improved, and the turn-on voltage of the light-emitting device 100 can be reduced.

[0250] In some embodiments, as shown in FIG. 5, in the case where the material of the second electron transport thin film 14B comprises doped zinc oxide, the doping element comprises one or a combination of any number of lithium (Li), magnesium (Mg), aluminum (Al), gallium (Ga), yttrium (Y) and copper (Cu).

[0251] For example, the material of the second electron transport thin film 14B comprises magnesium-doped zinc oxide (ZnMgO), i.e., zinc magnesium oxide.

[0252] It can be understood that when the doping element comprises one or a combination of any number of lithium (Li), magnesium (Mg), aluminum (Al), gallium (Ga), yttrium (Y) and copper (Cu), the feasibility of the doping element in regulating the performance (for example, the LUMO energy level) of the zinc oxide can be improved; and the above-mentioned doping elements have the advantages of being easy to obtain and having good compatibility with zinc oxide.

[0253] In some implementations, the first functional layer 140 includes the first electron transport thin film 14A, or, in the case of the first electron transport thin film 14A and the second electron transport thin film 14B, the first functional layer 140 can have a relatively strong conductivity and a relatively large electron mobility, which can easily cause the electrons to migrate to the side of the light-emitting layer 130 close to the anode 110. In addition, the quantum dot particles in the quantum dot light-emitting layer have a small contact area with the thin film, which can easily cause the phenomenon of electron leakage.

[0254] To this end, in some embodiments, as shown in FIG. 5, the light-emitting device 100 further includes a blocking layer 170. The blocking layer 170 is located between the light-emitting layer 130 and the anode 110. The blocking layer 170 is configured to prevent the electrons from leaking to the side of the light-emitting layer 130 away from the first functional layer 140.

[0255] In some examples, as shown in FIG. 5, the light-emitting device 100 further includes at least one hole transport functional layer between the light-emitting layer 130 and the anode 110. In this case, the blocking layer 170 can be arranged between the hole transport functional layer and the light-emitting layer 130. Here, the at least one hole transport functional layer includes, for example, one or both of the hole injection layer 150 and the hole transport layer 160.

[0256] Exemplarily, the material of the blocking layer 170 can be one or a combination of any number of ethoxylated polyethyleneimine (PEIE), 9,9-dioctylfluorene-9,9-bis(N,N-dimethylaminopropyl)fluorene (PFN), 2-methoxy-N-(3-methyl-2-oxo-1,2,3,4-tetrahydroquinazolin-6-yl)benzenesulfonamide (PFI), poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO), polymethyl methacrylate (PMMA), and aluminum trioxide (Al2O3).

[0257] As can be understood, by the above arrangement, the blocking layer 170 can achieve the effect of blocking the electrons, which can prevent the electrons transmitted by the first functional layer 140 from migrating or leaking to the side of the light-emitting layer 130 away from the first functional layer 140, and can inhibit the leakage current, thereby improving the performance of the light-emitting device 100.

[0258] As shown in FIG. 7, some embodiments of the present disclosure further provide a method for manufacturing a light-emitting device 100. The method for manufacturing the light-emitting device 100 includes S1.

[0259] S1: forming an anode 110, a cathode 120, a light-emitting layer 130, and a first functional layer 140. The anode 110 is arranged opposite to the cathode 120; the light-emitting layer 130 is located between the anode 110 and the cathode 120; the first functional layer 140 is located between the cathode 120 and the light-emitting layer 130; the first functional layer 140 has a first state and a second state, the first state being a state before an aging treatment, and the second state being a state after the aging treatment. Wherein, under the same preset conditions, a ratio between a current efficiency of the light-emitting device 100 containing the first functional layer 140 in the first state and a current efficiency of the light-emitting device 100 containing the first functional layer 140 in the second state is greater than or equal to 0.83.

[0260] Here, for the description of the first functional layer 140, the aging treatment, the same preset conditions, and the ratio between the first current efficiency and the second current efficiency, reference can be made to the aforementioned exemplary description of the first functional layer 140, the aging treatment, the preset conditions, and the ratio between the first current efficiency and the second current efficiency, which will not be repeated here.

[0261] The preparation method of the light-emitting device 100 has the same beneficial effects as those of the light-emitting device 100 described in some of the above embodiments, which will not be repeated here.

[0262] In some examples, the light-emitting device 100 is a normal light-emitting device, and the preparation method of the light-emitting device 100 can include R1-R4 as shown in FIG. 8. It should be noted that FIG. 8 shows the preparation process of one light-emitting device 100, and in actual application, other light-emitting devices 100 can also be formed in the process of preparing the light-emitting device 100, and the same applies to FIGS. 9 and 10 described in detail below.

[0263] R1: forming the anode 110 on the substrate 210.

[0264] Exemplarily, the process of forming the anode 110 can be a sputtering process or a photolithography process, etc.

[0265] R2: forming the light-emitting layer 130 on the side of the anode 110 away from the substrate 210.

[0266] Exemplarily, the process of forming the light-emitting layer 130 can be a printing process (e.g., an inkjet printing process) or a printing process.

[0267] Exemplarily, the material forming the light-emitting layer 130 comprises quantum dot light-emitting material and photosensitive material. In this case, the preparation method of the light-emitting layer 130 can comprise: coating the material forming the light-emitting layer 130, exposing the region where the target opening is located, and developing to remove the material of the light-emitting layer 130 in regions other than the exposed region. Here, the target opening refers to the opening in the plurality of openings corresponding to the prepared light-emitting device 100.

[0268] Through the above exposure process, the quantum dot light-emitting material and the photosensitive material can be cross-linked in the target opening (which can also be understood as the target pixel region), so as to achieve the purpose of selective patterning after development.

[0269] In some examples, after R1 and before R2, R1A-R1B are further included.

[0270] R1A: depositing a hole injection layer 150 on the side of the anode 110 away from the substrate 210.

[0271] Exemplarily, the process of forming the hole injection layer 150 is, for example, a spin coating process, a magnetron sputtering process or an evaporation process.

[0272] Exemplarily, the material of the hole injection layer 150 can be one or a combination of any number of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), molybdenum oxide (MoOx), nickel oxide (NiOx), tungsten oxide (WOx) and vanadium oxide (Vox).

[0273] Exemplarily, the thickness (i.e. the dimension along the first direction X) of the hole injection layer 150 can be 20-100 nm, for example 20 nm, 35 nm, 50 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0274] R1B: depositing a hole transport layer 160 on the side of the hole injection layer 150 away from the anode 110.

[0275] Exemplarily, the process of forming the hole transport layer 160 is, for example, a spin coating process, a magnetron sputtering process or an evaporation process.

[0276] Exemplarily, the material of the hole transport layer 160 can be 1,2,4,5-tetrakis(trifluoromethyl)benzene (TFB).

[0277] It should be understood that in the case where the preparation method of the light-emitting device 100 comprises R1A-R1B, in R2, the light-emitting layer 130 can be formed on the side of the hole transport layer 160 away from the hole injection layer 150.

[0278] R3: Forming the first functional layer 140 on the side of the light-emitting layer 130 away from the anode 110.

[0279] In some example embodiments, forming the first functional layer 140 includes R3.1-R3.3.

[0280] R3.1: Spin-coating a first solution on the light-emitting layer 130, the first solution being used to form a first sub-layer 14a, the first sub-layer 14a constituting a part of the first functional layer 140.

[0281] Exemplarily, the first solution can be spin-coated in a dynamic spin-coating manner; in some examples, after the dynamic spin-coating of the first solution, a film-forming annealing process can be performed on the material forming the first sub-layer 14a.

[0282] Exemplarily, the solvent contained in the first solution can be ethanol.

[0283] R3.2: Spin-coating a second solution on the side of the first sub-layer 14a away from the light-emitting layer 130, the second solution being used to form a second sub-layer 14b, the second sub-layer 14b constituting another part of the first functional layer 140. Herein, the molecular chain length of the solvent contained in the first solution (hereinafter referred to as the first solvent) is smaller than the molecular chain length of the solvent contained in the second solution (hereinafter referred to as the second solvent).

[0284] Exemplarily, the second solution can be spin-coated in a dynamic spin-coating manner; in some examples, after the dynamic spin-coating of the second solution, a film-forming annealing process can be performed on the material forming the second sub-layer 14b.

[0285] Exemplarily, the second solvent can be a long-chain alcohol or a long-chain ether with a molecular chain length greater than or equal to that of the first solvent, for example, butanol.

[0286] R3.3: Spin-coating a third solution on the side of the second sub-layer 14b away from the first sub-layer 14a, the third solution being used to form a third sub-layer 14c, the third sub-layer 14c constituting a further part of the first functional layer 140. Herein, the molecular chain length of the solvent contained in the second solution is smaller than or equal to the molecular chain length of the solvent contained in the third solution (hereinafter referred to as the third solvent).

[0287] Exemplarily, the third solution can be spin-coated in a dynamic spin-coating manner; in some examples, after the dynamic spin-coating of the third solution, a film-forming annealing process can be performed on the material forming the third sub-layer 14c.

[0288] Exemplarily, the third solvent can be a long-chain alcohol or a long-chain ether with a molecular chain length greater than or equal to that of the second solvent, for example, hexanol.

[0289] It can be understood that, in the above method of forming the first functional layer 140, on one hand, the film forming and annealing treatment can be performed on the material forming the first sub-layer 14a, the material forming the second sub-layer 14b, and the material forming the third sub-layer 14c, so that the material forming the subsequent film layer has less influence on the first sub-layer 14a, the second sub-layer 14b, and the third sub-layer 14c when the subsequent film layer is formed. For example, the film forming and annealing treatment can be performed on the material forming the first sub-layer 14a to increase the stability of the first sub-layer 14a, so that the second solution has a slower dissolution rate on the first sub-layer 14a, and the influence of the second solution on the first sub-layer 14a can be avoided.

[0290] On the other hand, by setting the molecular chain length of the first solvent to be less than the molecular chain length of the second solvent, and the molecular chain length of the second solvent to be less than or equal to the molecular chain length of the third solvent, the molecular chain length of the solvent used for spin coating can be gradually increased in the order of the formed film layers, so that the solubility of the previous film layer in the material of the subsequent film layer can be reduced, and the material forming the subsequent film layer has less influence on the first sub-layer 14a, the second sub-layer 14b, and the third sub-layer 14c when the subsequent film layer is formed. For example, by setting the molecular chain length of the first solvent to be less than the molecular chain length of the second solvent, the molecular chain length of the second solvent can be made longer, and the solubility of the second solvent on the material of the first sub-layer 14a can be reduced, so that the influence of the second solution on the first sub-layer 14a can be avoided.

[0291] R4: Forming a cathode 120 on the side of the first functional layer 140 away from the light-emitting layer 130.

[0292] Exemplarily, the material of the cathode 120 can be deposited by a magnetron sputtering method or an evaporation method to form the cathode 120.

[0293] In some other examples, the light-emitting device 100 is an inverted light-emitting device, and the preparation method of the light-emitting device 100 can include N1-N4 as shown in FIG. 9.

[0294] N1: Forming a cathode 120 on the substrate 210.

[0295] Exemplarily, the process of forming the cathode 120 can be a sputtering process or a photolithography process, etc.

[0296] N2: Forming a first functional layer 140 on the side of the cathode 120 away from the substrate 210.

[0297] Here, for the description of forming the first functional layer 140, reference can be made to the foregoing exemplary description of R3, which will not be repeated here.

[0298] N3: Forming a light-emitting layer 130 on the side of the first functional layer 140 away from the cathode 120.

[0299] Here, for the description of forming the light-emitting layer 130, reference can be made to the foregoing exemplary description of R2, which will not be repeated here.

[0300] N4: Forming the anode 110 on the side of the light-emitting layer 130 away from the first functional layer 140.

[0301] Exemplarily, the material of the anode 110 can be deposited in a magnetron sputtering manner to form the anode 110.

[0302] In some examples, after N3 and before N4, N3A-N3B are further included.

[0303] N3A: Depositing to form the hole transport layer 160 on the side of the light-emitting layer 130 away from the first functional layer 140.

[0304] N3B: Depositing to form the hole injection layer 150 on the side of the hole transport layer 160 away from the light-emitting layer 130.

[0305] Here, for the description of N3A, N3B, reference can be made to the foregoing exemplary description of R1B, R1A, which will not be repeated here.

[0306] In yet some embodiments, the light-emitting device 100 is an inverted light-emitting device, in which case, as shown in FIG. 10, the method for preparing the light-emitting device 100 can include U1-U4.

[0307] U1: Forming the patterned cathode 120 on the substrate 210.

[0308] Exemplarily, the process for forming the cathode 120 can be a sputtering process or a photolithography process, etc.

[0309] U2: Forming the first electron transport thin film 14A on the side of the cathode 120 away from the substrate 210, the first electron transport thin film 14A constituting at least part of the first functional layer 140.

[0310] In some examples, forming the first electron transport thin film 14A includes forming the first electron transport thin film 14A on the side of the cathode 120 away from the substrate 210 by a sputtering process. Here, the sputtering process can be a magnetron sputtering process.

[0311] In other examples, the first electron transport thin film 14A is formed on the side of the cathode 120 away from the substrate 210 by a sol-gel process.

[0312] U3: Forming the light-emitting layer 130 on the side of the first electron transport thin film 14A away from the cathode 120.

[0313] Here, for the description of forming the light-emitting layer 130, reference can be made to the foregoing exemplary description of R2, which will not be repeated here.

[0314] U4: Forming the anode 110 on the side of the light-emitting layer 130 away from the first functional layer 140.

[0315] Exemplarily, the material of the anode 110 can be deposited in a magnetron sputtering manner to form the anode 110.

[0316] In some examples, after U3 and before U4, U3B-U3C are further included.

[0317] U3B: Depositing to form the hole transport layer 160 on the side of the light-emitting layer 130 away from the first functional layer 140.

[0318] U3C: Depositing to form the hole injection layer 150 on the side of the hole transport layer 160 away from the light-emitting layer 130.

[0319] Here, for the description of U3B and U3C, reference can be made to the foregoing exemplary description of R1B and R1A, which will not be repeated here.

[0320] It can be understood that, in the first aspect, the first functional layer 140 formed in the preparation method includes the first electron transport thin film 14A in the form of a thin film, which can make the surface defects of the material of the first functional layer 140 less, and can alleviate the problem of positive aging of the light-emitting device 100, so that the process step of accelerating positive aging in the preparation process of the display panel 200 can be omitted, and the controllability and repeatability of the preparation process of the display panel 200 are improved.

[0321] On the other hand, the light-emitting device 100 obtained by the preparation method is an inverted light-emitting device, which can form the first functional layer 140 prior to the light-emitting layer 130, and can improve the uniformity of the light-emitting layer 130 and the light-emitting device 100 as a whole, compared with the case where the light-emitting layer 130 is formed prior to the hole injection layer 150 and the hole transport layer 160. Moreover, the first electron transport thin film 14A prepared by the sputtering process or the sol-gel process has high thickness uniformity, which can improve the uniformity of the light-emitting layer 130 and the light-emitting device 100 as a whole, is conducive to mass production of QLED display panels, and makes the light-emitting device 100 applicable to high-resolution QLED display panels.

[0322] In some embodiments, as shown in FIG. 10, after U2 and before U3, U2A is further included.

[0323] U2A: forming a second electron transport thin film 14B on a side of the first electron transport thin film 14A away from the cathode 120 by a sputtering process, or forming the second electron transport thin film 14B on a side of the first electron transport thin film 14A away from the cathode 120 by a sol-gel process. The second electron transport thin film 14B forms part of the first functional layer 140. The absolute value of the lowest unoccupied molecular orbital energy level of the material of the second electron transport thin film 14B is less than the absolute value of the lowest unoccupied molecular orbital energy level of the material of the first electron transport thin film 14A, and greater than the absolute value of the lowest unoccupied molecular orbital energy level of the material of the light-emitting layer 130.

[0324] It should be understood that in the case where the preparation method of the light-emitting device 100 further includes U2A, in U3, the light-emitting layer 130 can be formed on a side of the second electron transport thin film 14B away from the first electron transport thin film 14A.

[0325] It can be understood that, through the above arrangement, on the one hand, a stepped energy level structure can be formed between the first functional layer 140 and the light-emitting layer 130, which can improve the electron injection effect, so that the electron transport efficiency of the light-emitting device 100 is improved, and on the other hand, the electron utilization rate of the light-emitting device 100 can be improved, so that the light-emitting efficiency of the light-emitting device 100 is improved; and on the other hand, the turn-on voltage of the light-emitting device 100 can be reduced, and the brightness of the light-emitting device 100 can be improved.

[0326] In some embodiments, as shown in FIG. 10, after U3 and before U4, or after U3 and before U3B, U3A is further included.

[0327] U3A: forming a blocking layer 170 on a side of the light-emitting layer 130 away from the first functional layer 140. The blocking layer 170 is configured to prevent the leakage of electrons to the side of the light-emitting layer 130 away from the first functional layer 140.

[0328] It can be understood that, through such an arrangement, the blocking layer 170 can achieve the effect of blocking electrons, can prevent the migration or leakage of the electrons transmitted by the first functional layer 140 to the side of the light-emitting layer 130 away from the first functional layer 140, and can inhibit the leakage current, so that the performance of the light-emitting device 100 is improved.

[0329] In order to objectively evaluate the technical effects of the embodiments of the present disclosure, in the following, the technical solutions provided by the present disclosure will be described in detail by the following experimental examples and comparative examples. According to the evaluation purpose of the experimental examples, the following experimental examples and comparative examples are divided into first group test examples, second group test examples and third group test examples.

[0330]

First group test example

[0331] The following Example 1, Example 2, Comparative Example 1 and Comparative Example 2 prepared the luminescent device 100 including the nanoparticles in the first functional layer 140 with different particle sizes. Among them, the structure of the luminescent device 100 is the same as that of the luminescent device 100 in FIG. 2.

[0332] In Example 1, Example 2, Comparative Example 1 and Comparative Example 2, the preparation method of the luminescent device 100 includes R1-R4 described in the foregoing part, and the luminescent device 100 is packaged by using a non-acrylic type packaging glue. Moreover, in Example 1, Example 2, Comparative Example 1 and Comparative Example 2, a plurality of luminescent devices 100 are prepared.

[0333] In Example 1, Example 2, Comparative Example 1 and Comparative Example 2, the thickness and material of each film layer are the same, that is, in this group of test examples, the film layer thickness and film layer material of the luminescent device 100 are not distinguished. Among them, in Example 1, Example 2, Comparative Example 1 and Comparative Example 2, the nanoparticles included in the first functional layer 140 are all zinc oxide nanoparticles, but the particle sizes of the zinc oxide nanoparticles included in the first functional layer 140 in Example 1, Example 2, Comparative Example 1 and Comparative Example 2 are different.

[0334] In Example 1, Example 2, Comparative Example 1 and Comparative Example 2, the particle sizes of the nanoparticles included in the first functional layer 140 in Example 1 and Example 2, and Comparative Example 1 and Comparative Example 2 are qualitatively measured by using ultraviolet absorption spectrum, and the results are shown in FIG. 11.

[0335] Because the smaller the wavelength corresponding to the absorption peak in the ultraviolet absorption spectrum, the smaller the particle size of the nanoparticles. As can be seen from FIG. 11, the absorption peak position of Example 1 and Example 2 is red-shifted relative to the absorption peak position of Comparative Example 1 and Comparative Example 2, indicating that the particle size of the nanoparticles in Example 1 and Example 2 is larger. Moreover, the absorption peak position of Example 2 is red-shifted relative to the absorption peak position of Example 1 by a larger distance, indicating that the particle size of the nanoparticles in Example 1 is smaller than the particle size of the nanoparticles in Example 2.

[0336] In Example 1, Example 2, Comparative Example 1 and Comparative Example 2, the particle sizes of the nanoparticles included in the first functional layer 140 in Example 1 and Example 2, and Comparative Example 1 and Comparative Example 2 are quantitatively measured by using a transmission electron microscope, and the results are shown in FIG. 12. Among them, the subgraph marked with Z1 in FIG. 12 is the transmission electron microscope image of the nanoparticles in Comparative Example 1; the subgraph marked with Z2 in FIG. 12 is the transmission electron microscope image of the nanoparticles in Comparative Example 2; the subgraph marked with Z3 in FIG. 12 is the transmission electron microscope image of the nanoparticles in Example 1; and the subgraph marked with Z4 in FIG. 12 is the transmission electron microscope image of the nanoparticles in Example 2.

[0337] From the TEM results, the particle size of the nanoparticles in Example 1 is 5.0 nm; the particle size of the nanoparticles in Example 2 is 6.0 nm; the particle size of the nanoparticles in Comparative Example 1 is 3.5 nm; and the particle size of the nanoparticles in Comparative Example 2 is 3.6 nm.

[0338] Based on the above settings, the current efficiencies of the light-emitting devices 100 in Example 1, Example 2, Comparative Example 1 and Comparative Example 2 before and after the aging treatment were compared. Specifically, a part of the light-emitting devices 100 in Example 1 were subjected to the aging treatment, and another part of the light-emitting devices 100 were not subjected to the aging treatment. Then, the current efficiency versus luminance curves of the light-emitting devices 100 subjected to the aging treatment and not subjected to the aging treatment were measured, and the results are shown in FIG. 13. Similarly, the current efficiency versus luminance curves of the light-emitting devices 100 subjected to the aging treatment and not subjected to the aging treatment in Example 2 were measured, and the results are shown in FIG. 14. The current efficiency versus luminance curves of the light-emitting devices 100 subjected to the aging treatment and not subjected to the aging treatment in Comparative Example 1 were measured, and the results are shown in FIG. 15. The current efficiency versus luminance curves of the light-emitting devices 100 subjected to the aging treatment and not subjected to the aging treatment in Comparative Example 2 were measured, and the results are shown in FIG. 16.

[0339] In Example 1, Example 2, Comparative Example 1 and Comparative Example 2, the aging treatment was performed by placing the light-emitting device intermediate product including the anode 110, the light-emitting layer 130 and the first functional layer 140 in an acrylic atmosphere for 30 min after forming the first functional layer 140 and before forming the cathode 120, so as to achieve the purpose of accelerating the positive aging.

[0340] From FIGS. 13-16, it can be seen that in Comparative Example 1 and Comparative Example 2, under the condition of relative luminance, the current efficiency of the light-emitting device 100 subjected to the aging treatment is obviously improved relative to the current efficiency of the light-emitting device 100 not subjected to the aging treatment, indicating that the light-emitting device 100 in Comparative Example 1 and Comparative Example 2 has a relatively obvious positive aging phenomenon after the aging treatment. In Example 1 and Example 2, under the condition of relative luminance, the current efficiency of the light-emitting device 100 subjected to the aging treatment is not obviously improved relative to the current efficiency of the light-emitting device 100 not subjected to the aging treatment, and the improvement ratio of the current efficiency is less than 20%, indicating that the light-emitting device 100 in Example 1 and Example 2 does not have a significant positive aging phenomenon after the aging treatment, and even in Example 2, a relatively small negative aging phenomenon occurs.

[0341] It can be seen that when the first functional layer 140 includes nanoparticles with a particle size in the range of 4-6 nm, the positive aging problem of the light-emitting device 100 can be effectively alleviated.

[0342]

Second Group of Test Examples

[0343] The following Example 3, Example 4 and Comparative Example 3 prepared luminescent devices 100 with different contents of the ligand material of the nanoparticles included in the first functional layer 140. Among them, the structure of the luminescent device 100 is the same as that of the luminescent device 100 in FIG. 2.

[0344] In Example 3, Example 4 and Comparative Example 3, the preparation method of the luminescent device 100 includes R1-R4 described in the foregoing part, and the luminescent device 100 is packaged with a non-acrylic type packaging glue. Moreover, in Example 3, Example 4 and Comparative Example 3, a plurality of luminescent devices 100 are prepared.

[0345] In Example 3, Example 4 and Comparative Example 3, the thickness and material of each film layer are the same, that is, in this group of test examples, the film layer thickness and film layer material of the luminescent device 100 are not distinguished. Among them, in Example 3, Example 4 and Comparative Example 3, the nanoparticles included in the first functional layer 140 include metal oxide material and ligand material, and the metal oxide material is magnesium-doped zinc oxide, but in Example 3, Example 4 and Comparative Example 3, the mass ratio of the ligand material in the nanoparticles in the first functional layer 140 is different. Specifically, the mass ratio of the ligand material in the nanoparticles in Example 3 is 16%, the mass ratio of the ligand material in the nanoparticles in Example 4 is 25%, and the mass ratio of the ligand material in the nanoparticles in Comparative Example 3 is 14%.

[0346] Based on the above settings, the current efficiency of the luminescent devices 100 in Example 3, Example 4 and Comparative Example 3 before and after aging treatment was compared. Specifically, a part of the luminescent devices 100 in Example 3 were subjected to aging treatment, and another part of the luminescent devices 100 were not subjected to aging treatment, and then the current efficiency versus luminance curves of the luminescent devices 100 subjected to aging treatment and not subjected to aging treatment were measured, and the results are shown in FIG. 17. Similarly, the current efficiency versus luminance curves of the luminescent devices 100 subjected to aging treatment and not subjected to aging treatment in Example 4 were measured, and the results are shown in FIG. 18. The current efficiency versus luminance curves of the luminescent devices 100 subjected to aging treatment and not subjected to aging treatment in Comparative Example 3 were measured, and the results are shown in FIG. 19.

[0347] Among them, in Example 3, Example 4 and Comparative Example 3, the aging treatment is as follows: after the formation of the first functional layer 140 and before the formation of the cathode 120, the luminescent device 100 including the anode 110, the luminescent layer 130 and the first functional layer 140 is placed in an acrylic atmosphere for 30 min to achieve the purpose of accelerated positive aging.

[0348] As can be seen from FIGS. 17-19, in Comparative Example 3, the current efficiency of the light-emitting device 100 after the aging treatment is significantly improved relative to the current efficiency of the light-emitting device 100 before the aging treatment under the relative brightness condition, indicating that the light-emitting device 100 in Comparative Example 3 exhibits a significant positive aging phenomenon after the aging treatment. In Example 3 and Example 4, the current efficiency of the light-emitting device 100 after the aging treatment is not significantly improved relative to the current efficiency of the light-emitting device 100 before the aging treatment under the relative brightness condition, and the current efficiency is improved by less than 20%, indicating that the light-emitting device 100 in Example 3 and Example 4 does not exhibit a significant positive aging phenomenon after the aging treatment, and even exhibits a small degree of negative aging phenomenon in Example 4.

[0349] It can be seen that when the mass proportion of the ligand material in the nanoparticles in the first functional layer 140 is 16%-25%, the positive aging problem of the light-emitting device 100 can be effectively alleviated.

[0350]

Third Group of Test Examples

[0351] Examples 5-8 below prepared display panels 200 with different thickness ratios and materials of the first electron transport thin film 14A and the second electron transport thin film 14B included in the first functional layer 140. The structure of the display panel 200 in Examples 5-8 is shown in FIG. 20. Comparative Example 4 prepared a display panel 200 including the first electron transport thin film 14A in the first functional layer 140 but not including the second electron transport thin film 14B. The structure of the display panel 200 in Comparative Example 4 is shown in FIG. 21.

[0352] In Examples 5-8 and Comparative Example 4, the method for preparing the display panel 200 includes the following steps.

[0353] (1) Providing a back plate including a substrate 210, a driving circuit disposed on the substrate 210, and a patterned cathode 120 disposed on one side of the substrate 210.

[0354] (2) Forming a pixel defining layer 221.

[0355] (3) Forming the first functional layer 140 on the side of the cathode 120 away from the substrate 210 using a magnetron sputtering process.

[0356] (4) Depositing a light-emitting layer 130 on the side of the first functional layer 140 away from the cathode 120 using an inkjet printing process. The material of the light-emitting layer 130 includes quantum dot light-emitting material.

[0357] (5) Forming a barrier layer 170 on the side of the light-emitting layer 130 away from the first functional layer 140.

[0358] (6) The hole transport layer 160 and the hole injection layer 150 are formed in sequence on the side of the barrier layer 170 away from the light-emitting layer 130 by using an evaporation process.

[0359] (7) The anode 110 is formed on the side of the hole injection layer 150 away from the hole transport layer 160 by using a magnetron sputtering process.

[0360] In the examples 5-8 and the comparative example 4, the thicknesses of the film layers other than the first functional layer 140 and the materials of the film layers other than the first functional layer 140 and the light-emitting layer 130 are the same, that is, in the present test examples, the thicknesses of the film layers other than the first functional layer 140 and the materials of the film layers other than the first functional layer 140 and the light-emitting layer 130 in the light-emitting device 100 in the display panel 200 are not distinguished. In the examples 5-8 and the comparative example 4, the material of the first electron transport thin film 14A includes zinc oxide. In the examples 5-8, the material of the second electron transport thin film 14B includes magnesium-doped zinc oxide, and in the examples 5-8, the thickness ratio of the first electron transport thin film 14A to the second electron transport thin film 14B and the mass percentage of magnesium in the magnesium-doped zinc oxide in the second electron transport thin film 14B are distinguished, and the specific settings are as follows.

[0361] In the example 5, the thickness ratio of the first electron transport thin film 14A to the second electron transport thin film 14B is 1:1, and the mass percentage of magnesium in the magnesium-doped zinc oxide in the second electron transport thin film 14B is 2%.

[0362] In the example 6, the thickness ratio of the first electron transport thin film 14A to the second electron transport thin film 14B is 1:1, and the mass percentage of magnesium in the magnesium-doped zinc oxide in the second electron transport thin film 14B is 5%.

[0363] In the example 7, the thickness ratio of the first electron transport thin film 14A to the second electron transport thin film 14B is 1:1, and the mass percentage of magnesium in the magnesium-doped zinc oxide in the second electron transport thin film 14B is 8%.

[0364] In the example 8, the thickness ratio of the first electron transport thin film 14A to the second electron transport thin film 14B is 3:1, and the mass percentage of magnesium in the magnesium-doped zinc oxide in the second electron transport thin film 14B is 5%.

[0365] Based on the above settings, the luminance-voltage curve of the light emitting device 100 in Examples 5 to 7 and Comparative Example 4 was measured, as shown in FIG. 22. The current density-voltage curve and the luminance-voltage curve of the light emitting device 100 in Example 8 and Comparative Example 4 were measured, as shown in FIG. 23. In addition, the current efficiency-current density curve of the light emitting device 100 in Example 8 and Comparative Example 4 was measured, as shown in FIG. 24. It should be noted that in FIGS. 22 to 24, the luminance, current density or current efficiency of the light emitting device 100 is the average value of the luminance, current density or current efficiency of the plurality of light emitting devices 100 in the display panel 200.

[0366] As can be seen from FIG. 22, the luminance of the light emitting device 100 in Examples 5 and 6 is higher and the turn-on voltage is lower than that in Comparative Example 4, because the first functional layer 140 in Examples 5 and 6 includes the first electron transport thin film 14A and the second electron transport thin film 14B, while the first functional layer 140 in Comparative Example 4 includes the first electron transport thin film 14A but does not include the second electron transport thin film 14B. When the first functional layer 140 includes the first electron transport thin film 14A and the second electron transport thin film 14B, a stepped energy level structure can be formed between the first functional layer 140 and the light emitting layer 130, which can improve the electron injection effect, improve the electron transport efficiency of the light emitting device 100, improve the electron utilization rate of the light emitting device 100, and improve the luminous efficiency of the light emitting device 100. At the same time, the turn-on voltage of the light emitting device 100 can be reduced, and the luminance of the light emitting device 100 can be improved.

[0367] In addition, as can be seen from FIG. 22, the luminance of the light emitting device 100 in Example 7 is lower and the turn-on voltage is lower than that in Examples 5 and 6, because the mass fraction of magnesium in the material of the second electron transport thin film 14B in Example 7 is relatively high, which makes the LUMO energy level of the second electron transport thin film 14B in Example 7 relatively high, increases the barrier between the second electron transport thin film 14B and the first electron transport thin film 14A, and makes the electron injection barrier between the second electron transport thin film 14B and the first electron transport thin film 14A relatively high, which makes the electron injection relatively difficult.

[0368] As shown in FIG. 23 and FIG. 24, the current density of Example 8 is lower, the luminance is higher, and the current efficiency is higher than those of Comparative Example 4. This is because the first functional layer 140 of Example 8 includes the first electron transport thin film 14A and the second electron transport thin film 14B, while the first functional layer 140 of Comparative Example 4 includes the first electron transport thin film 14A and does not include the second electron transport thin film 14B. When the first functional layer 140 includes the second electron transport thin film 14B, and the material of the second electron transport thin film 14B includes magnesium-doped zinc oxide, the electron mobility of the material of the second electron transport thin film 14B is lower, which reduces the current density of the light emitting device 100. When the first functional layer 140 includes the first electron transport thin film 14A and the second electron transport thin film 14B, the potential barrier for the injection of electrons from the first functional layer 140 to the light emitting layer 130 can be reduced, which increases the luminance of the light emitting device 100. Furthermore, when the first functional layer 140 includes the first electron transport thin film 14A and the second electron transport thin film 14B, a stepped energy level structure can be formed between the first functional layer 140 and the light emitting layer 130, which can improve the electron injection effect, increase the electron utilization rate of the light emitting device 100, and improve the light emitting efficiency of the light emitting device 100. As shown in FIG. 24, the current efficiency of the light emitting device 100 of Example 8 can be 1.6 times that of the light emitting device 100 of Comparative Example 4.

[0369] The above merely provides a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art can think of changes or replacements within the technical scope disclosed by the present disclosure, which should be covered by the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A light emitting device, comprising: a cathode and an anode arranged oppositely; a light emitting layer between the anode and the cathode; and a first functional layer between the cathode and the light emitting layer; the first functional layer has a first state and a second state, the first state is a state before aging treatment, and the second state is a state after aging treatment; wherein, under the same preset conditions, the ratio between the current efficiency of the light emitting device containing the first functional layer in the first state and the current efficiency of the light emitting device containing the first functional layer in the second state is greater than or equal to 0.

83. The same preset conditions include the same current density and / or the same brightness.

2. The light-emitting device according to claim 1, wherein The material of the first functional layer includes first nanoparticles, and the particle size of the first nanoparticles is 4 nm to 6 nm.

3. The light emitting device according to claim 1 or 2, wherein The material of the first functional layer further includes second nanoparticles; the particle size of the second nanoparticles is smaller than the particle size of the first nanoparticles.

4. The light emitting device of claim 3, wherein, The material of the first functional layer includes third nanoparticles, and the third nanoparticles include a first metal oxide material and a first ligand material coordinated to the first metal oxide material; the mass percentage of the first ligand material in the third nanoparticles is 16% to 25%.

5. The light-emitting device according to any one of claims 1 to 4, wherein The material of the first functional layer further includes fourth nanoparticles, and the fourth nanoparticles include a second metal oxide material and a second ligand material coordinated to the second metal oxide material; the mass percentage of the second ligand material in the fourth nanoparticles is smaller than the mass percentage of the first ligand material in the third nanoparticles.

6. The light-emitting device according to claim 5, wherein The first ligand material includes ethanolamine; and / or 7. The light emitting device according to claim 5 or 6, wherein In the case where the material of the first functional layer includes the fourth nanoparticles, the second ligand material includes ethanolamine. The first functional layer includes a first sub-layer, a second sub-layer and a third sub-layer arranged in a first direction; the second sub-layer is between the first sub-layer and the third sub-layer; the first direction is the arrangement direction of the anode and the cathode; 8. The light-emitting device according to any one of claims 1 to 7, wherein wherein, the electron mobility of the material of the second sub-layer is greater than or equal to the electron mobility of the material of the first sub-layer; and / or, the electron mobility of the material of the second sub-layer is greater than or equal to the electron mobility of the material of the third sub-layer. In the case where the material of the first functional layer includes the first nanoparticles and the second nanoparticles, the first nanoparticles are arranged in the first sub-layer and / or the third sub-layer; and the second nanoparticles are arranged in the second sub-layer.

9. The light-emitting device according to claim 8, wherein The particle size of the first nanoparticles is 5 nm to 6 nm, and the particle size of the second nanoparticles is 3 nm to 4 nm.

10. The light-emitting device according to any one of claims 4 to 9, wherein The absolute value of the lowest unoccupied molecular orbital energy level of the material of the second sub-layer is greater than or equal to the absolute value of the lowest unoccupied molecular orbital energy level of the material of the first sub-layer; and / or, the absolute value of the lowest unoccupied molecular orbital energy level of the material of the second sub-layer is greater than or equal to the absolute value of the lowest unoccupied molecular orbital energy level of the material of the third sub-layer.

11. The light-emitting device according to any one of claims 8 to 10, wherein ​ 12. The light-emitting device according to any one of claims 8 to 11, wherein In the case that the material of the first functional layer comprises the third nanoparticles and the fourth nanoparticles, the third nanoparticles are arranged in the first sub-layer and / or the third sub-layer; and the fourth nanoparticles are arranged in the second sub-layer.

13. The light-emitting device according to any one of claims 6 to 12, wherein The mass percentage of the second ligand material in the fourth nanoparticles is 10% to 15%.

14. The light-emitting device according to any one of claims 3 to 13, wherein The first nanoparticles comprise one or any combination of zinc oxide and doped zinc oxide; In the case that the material of the first functional layer comprises the second nanoparticles, the second nanoparticles comprise one or any combination of zinc oxide and doped zinc oxide; In the case that the material of the first functional layer comprises the third nanoparticles, the first metal oxide material comprises one or any combination of zinc oxide and doped zinc oxide; In the case that the material of the first functional layer comprises the fourth nanoparticles, the second metal oxide material comprises one or any combination of zinc oxide and doped zinc oxide; The doped zinc oxide comprises a doping element.

15. The light-emitting device according to claim 14, wherein The mass percentage of the doping element in the doped zinc oxide is 1% to 20%.

16. The light-emitting device according to claim 14 or 15, wherein In the case that the first nanoparticles are arranged in the first sub-layer and / or the third sub-layer, and the first nanoparticles comprise the zinc oxide, the highest occupied molecular orbital energy level of the first nanoparticles is -7.5 eV to -8.0 eV, and / or the lowest unoccupied molecular orbital energy level of the first nanoparticles is -3.8 eV to -4.0 eV.

17. The light-emitting device according to any one of claims 14 to 16, wherein In the case that the material of the first functional layer further comprises the second nanoparticles arranged in the second sub-layer, and the second nanoparticles comprise the zinc oxide, the highest occupied molecular orbital energy level of the second nanoparticles is -7.5 eV to -8.0 eV, and / or the lowest unoccupied molecular orbital energy level of the second nanoparticles is -4.0 eV to -4.3 eV.

18. The light-emitting device according to claim 1 or 2, wherein The first functional layer comprises a first electron transport thin film.

19. The light-emitting device according to claim 18, wherein The light-emitting device is arranged on a substrate; and the cathode is closer to the substrate than the anode.

20. The light-emitting device according to claim 18 or 19, wherein The first functional layer further comprises a second electron transport thin film; and the first electron transport thin film is closer to the cathode than the second electron transport thin film. The absolute value of the lowest unoccupied molecular orbital energy level of the material of the second electron transport thin film is smaller than the absolute value of the lowest unoccupied molecular orbital energy level of the material of the first electron transport thin film, and larger than the absolute value of the lowest unoccupied molecular orbital energy level of the material of the light-emitting layer.

21. The light-emitting device according to claim 20, wherein The lowest unoccupied molecular orbital energy level of the material of the first electron transport thin film is -4.7 eV to -4.2 eV; and / or The lowest unoccupied molecular orbital energy level of the material of the second electron transport thin film is -4.2 eV to -3.8 eV.

22. The light-emitting device according to claim 20 or 21, wherein The ratio between the size of the first electron transport thin film along a first direction and the size of the second electron transport thin film along the first direction ranges from 1:1 to 3:1, and the first direction is the arrangement direction of the anode and the cathode.

23. The light-emitting device according to any one of claims 20 to 22, wherein The material of the first electron transport thin film comprises zinc oxide; and the material of the second electron transport thin film comprises doped zinc oxide.

24. The light-emitting device according to claim 23, wherein The mass percentage of the doping element in the doped zinc oxide is greater than 0% and less than or equal to 10%.

25. The light-emitting device according to any one of claims 14 to 24, wherein In a case where one or more of the first nanoparticles, the second nanoparticles, the first metal oxide material, and the second metal oxide material comprises the doped zinc oxide, or In a case where the material of the second electron transport thin film comprises the doped zinc oxide, The doping element comprises one or a combination of any multiple of lithium, magnesium, aluminum, gallium, yttrium, and copper.

26. The light-emitting device according to any one of claims 18 to 25, wherein Further comprising: a blocking layer between the light-emitting layer and the anode; the blocking layer is configured to prevent electron leakage to a side of the light-emitting layer away from the first functional layer.

27. A method for manufacturing a light-emitting device, comprising: forming an anode, a cathode, a light-emitting layer, and a first functional layer; the anode and the cathode are oppositely arranged; the light-emitting layer is between the anode and the cathode; the first functional layer is between the cathode and the light-emitting layer; the first functional layer has a first state and a second state, the first state is a state before aging treatment, and the second state is a state after aging treatment; wherein, under a preset condition, the ratio between the current efficiency of the light-emitting device containing the first functional layer in the first state and the current efficiency of the light-emitting device containing the first functional layer in the second state is greater than or equal to 0.

83.

28. The method of producing a light emitting device according to Claim 27, wherein forming the first functional layer, comprising: spinning a first solution on the light-emitting layer, the first solution being used to form a first sub-layer, the first sub-layer constituting a part of the first functional layer; spinning a second solution on a side of the first sub-layer away from the light-emitting layer, the second solution being used to form a second sub-layer, the second sub-layer constituting another part of the first functional layer; and spinning a third solution on a side of the second sub-layer away from the first sub-layer, the third solution being used to form a third sub-layer, the third sub-layer constituting a further part of the first functional layer; wherein the molecular chain length of the solvent contained in the first solution is less than the molecular chain length of the solvent contained in the second solution; and the molecular chain length of the solvent contained in the second solution is less than or equal to the molecular chain length of the solvent contained in the third solution.

29. The method of producing a light emitting device according to Claim 27, wherein the forming of the anode, the cathode, the light-emitting layer, and the first functional layer, comprising: forming a patterned cathode on a substrate; forming a first electron transport thin film on a side of the cathode away from the substrate, the first electron transport thin film constituting at least part of the first functional layer; forming a light-emitting layer on a side of the first electron transport thin film away from the cathode; and forming the anode on a side of the light-emitting layer away from the first functional layer; wherein the forming of the first electron transport thin film, comprising: forming the first electron transport thin film on a side of the cathode away from the substrate by a sputtering process, or The first electron transport thin film is formed on a side of the cathode distal from the substrate by a sol-gel process.

30. The method of producing a light emitting device according to Claim 29, wherein The forming of the anode, the cathode, the light-emitting layer, and the first functional layer further comprises: forming a second electron transport thin film on a side of the first electron transport thin film distal from the cathode by a sputtering process, or forming a second electron transport thin film on a side of the first electron transport thin film distal from the cathode by a sol-gel process; wherein the second electron transport thin film forms part of the first functional layer; the absolute value of the lowest unoccupied molecular orbital energy level of the material of the second electron transport thin film is less than the absolute value of the lowest unoccupied molecular orbital energy level of the material of the first electron transport thin film, and greater than the absolute value of the lowest unoccupied molecular orbital energy level of the material of the light-emitting layer.

31. A display panel comprising a plurality of pixel driving circuits and a plurality of light-emitting devices according to any one of claims 1-26; the pixel driving circuits being configured to drive the light-emitting devices to emit light.

32. The display panel of claim 31, wherein, The display panel further comprises: a substrate; the plurality of light-emitting devices being disposed on a side of the substrate; and an encapsulation layer disposed on a side of the plurality of light-emitting devices distal from the substrate; the material of the encapsulation layer comprising a neutral organic material and / or a basic organic material. The display panel further comprises: a substrate; the plurality of light-emitting devices being disposed on a side of the substrate; and an encapsulation layer disposed on a side of the plurality of light-emitting devices distal from the substrate; the material of the encapsulation layer comprising a neutral organic material and / or a basic organic material.

Images