Quantum dot composition, light-emitting element, display panel and preparation method therefor

Abstract

The present disclosure belongs to the technical field of display, and provides a quantum dot composition, a light-emitting element, a display panel and a preparation method therefor. The quantum dot composition comprises a quantum dot body, a ligand and a cross-linking agent, wherein the ligand and the quantum dot body are in coordinate bonding; one of the ligand and the cross-linking agent has a sulfhydryl group protected by a photolabile group; the photolabile group can be desorbed under illumination to release a sulfhydryl group, a sulfur radical or a sulfur anion; when the released sulfhydryl group, sulfur radical or sulfur anion is located on the cross-linking agent, the released sulfhydryl group, sulfur radical or sulfur anion is used for coordinate bonding to the quantum dot body or used for reacting with the ligand to form a chemical bond; and when the released sulfhydryl group, sulfur radical or sulfur anion is located on the ligand, the released sulfhydryl group, sulfur radical or sulfur anion is used for reacting with the cross-linking agent to form a chemical bond. The quantum dot composition can be used to prepare a quantum dot layer of a display panel by means of a photolithography process. (FIG. 1)

Description

Quantum dot composition, light-emitting element, display panel and preparation method thereof

[0001] Cross-references

[0002] The present disclosure claims priority to PCT international patent application No. PCT / CN2024 / 076770 filed on February 7, 2024, entitled “Quantum dot compositions, light-emitting elements, display panels and methods for preparing the same,” and the entire contents of the PCT international patent application are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to the field of display technology, and in particular to a quantum dot composition, a light-emitting element, a display panel, and a preparation method thereof. Background Art

[0004] With the advancement of quantum dot fabrication technology, the stability and luminous efficiency of quantum dots have continued to improve. Research on quantum dot light-emitting diodes (QLEDs) continues to deepen, and the prospects for QLED applications in the display field are becoming increasingly promising. However, QLED efficiency has not yet reached mass production levels. One key reason is that breakthroughs in high-resolution patterning technology for QLEDs have yet to be achieved. The inorganic nanoparticle nature of quantum dots makes them difficult to form and pattern through vapor deposition, and inkjet printing methods struggle to achieve high resolution.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in the field.

[0006] Summary of the Invention

[0007] The purpose of the present disclosure is to overcome the deficiencies of the above-mentioned prior art and to provide a quantum dot composition, a light-emitting element, a display panel and a preparation method thereof, which are used to prepare the display panel through a photolithography process.

[0008] According to one aspect of the present disclosure, there is provided a quantum dot composition comprising a quantum dot body, a ligand, and a cross-linking agent;

[0009] The ligand is coordinated and connected with the quantum dot body;

[0010] wherein one of the ligand and the cross-linking agent has a thiol group protected by a photolyzable group;

[0011] The photolyzable group can be removed under light to release a sulfhydryl group, a sulfhydryl radical or a sulfhydryl anion;

[0012] When the released thiol group, thiol free radical or thiol anion is located on the cross-linking agent, the released thiol group, thiol free radical or thiol anion is used to coordinate with the quantum dot body or to react with the ligand to form a chemical bond; when the released thiol group, thiol free radical or thiol anion is located on the ligand, the released thiol group, thiol free radical or thiol anion is used to react with the cross-linking agent to form a chemical bond.

[0013] According to one embodiment of the present disclosure, the photolyzable group is selected from the following substituents:

[0014] Wherein, Ar1 is selected from an aryl group having a nitro group or a hydroxyl group, or a heteroaryl group having a nitro group or a hydroxyl group; R1, R2 and R3 are each independently selected from hydrogen, deuterium, or an alkyl group having 1 to 6 carbon atoms.

[0015] According to one embodiment of the present disclosure, the photolyzable group is selected from the following substituents:

[0016] Wherein, R5 is selected from hydrogen, deuterium, and an alkoxy group having 1 to 8 carbon atoms.

[0017] According to one embodiment of the present disclosure, the cross-linking agent has a plurality of thiol groups protected by photolyzable groups; the ligand has an active alkenyl group, and the active alkenyl group includes an alkenyl group and an electron-withdrawing group connected to the alkenyl group.

[0018] According to one embodiment of the present disclosure, the cross-linking agent has a first linking group, and the thiol group protected by the photolyzable group is connected to the first linking group.

[0019] According to one embodiment of the present disclosure, the structural formula of the ligand is ABCD or ABD; wherein A is a coordination group capable of coordinating with the quantum dot; B is a second connecting group; C is a carrier transport regulating group; and D is the active alkenyl group.

[0020] According to one embodiment of the present disclosure, the ligand has the thiol group protected by the photolyzable group; the cross-linking agent has a plurality of active alkenyl groups, and the active alkenyl groups include an alkenyl group and an electron-withdrawing group connected to the alkenyl group.

[0021] According to one embodiment of the present disclosure, the cross-linking agent has a first connecting group, and the active alkenyl group is connected to the first connecting group.

[0022] According to one embodiment of the present disclosure, the structural formula of the ligand is ABCD or ABD; wherein A is a coordination group capable of coordinating with the quantum dot; B is a second connecting group; C is a carrier transport regulating group; and D is the thiol group protected by the photolyzable group.

[0023] According to one embodiment of the present disclosure, the coordination group has an amino group, a carboxylic acid group, a thiol group, two thiol groups, a phosphine group or a phosphineoxy group.

[0024] According to one embodiment of the present disclosure, the active alkenyl group is selected from the following groups:

[0025] Wherein, R4 is selected from hydrogen, deuterium, and an alkyl group having 1 to 6 carbon atoms; and EWG is an electron withdrawing group.

[0026] According to one embodiment of the present disclosure, the active alkenyl group is selected from the following groups:

[0027] According to one embodiment of the present disclosure, the cross-linking agent has a plurality of thiol groups protected by photolyzable groups;

[0028] In the quantum dot body and the ligand, the mass ratio of the ligand is no more than 30%.

[0029] According to one embodiment of the present disclosure, in the quantum dot body and the ligand, the mass ratio of the ligand is no more than 15%.

[0030] According to one embodiment of the present disclosure, in the quantum dot body and the ligand, the mass ratio of the ligand is between 15% and 30%;

[0031] The acidity of the ligand is less than the acidity of the thiol group protected by the photolyzable group after the protecting group is removed.

[0032] According to one embodiment of the present disclosure, the ligand is selected from oleic acid, oleylamine, octanethiol, and dodecanethiol.

[0033] According to one embodiment of the present disclosure, the mass content of the cross-linking agent is 1% to 5%.

[0034] According to a second aspect of the present disclosure, a light-emitting element is provided, wherein the light-emitting element comprises a quantum dot layer; the quantum dot layer comprises quantum dot bodies interconnected by an organic material;

[0035] The organic material includes a ligand group coordinated with the quantum dot body and a cross-linking group connected to multiple ligand groups, and a thioether structure is formed between the ligand group and the cross-linking group; or, the organic material has multiple thiol groups, thiol radicals or thiol anions and is coordinated with multiple quantum dot bodies through thiol groups, thiol radicals or thiol anions.

[0036] According to a third aspect of the present disclosure, a display panel is provided, comprising the above-mentioned light-emitting element.

[0037] According to a fourth aspect of the present disclosure, a method for manufacturing a display panel is provided, comprising: sequentially forming quantum dot layers of at least two sub-pixels on a surface of a substrate by a photolithography process; forming any one of the quantum dot layers of the sub-pixels comprises:

[0038] forming a quantum dot composition film layer on the surface of the substrate using the quantum dot composition corresponding to the sub-pixel, wherein the quantum dot composition is selected from the above-mentioned quantum dot composition;

[0039] exposing and developing the quantum dot composition film layer corresponding to the sub-pixel to obtain the quantum dot layer of the sub-pixel;

[0040] The quantum dot layers of different sub-pixels contain different quantum dots in the quantum dot compositions.

[0041] According to one embodiment of the present disclosure, the method for preparing the display panel further includes:

[0042] Before forming the quantum dot layer, a hole transport layer is formed for each of the sub-pixels.

[0043] According to one embodiment of the present disclosure, the method for preparing the display panel further includes:

[0044] After forming the quantum dot layer of each sub-pixel, an electron transport layer of each sub-pixel is formed.

[0045] According to one embodiment of the present disclosure, forming a quantum dot composition film layer on the surface of the substrate using the quantum dot composition corresponding to the sub-pixel includes:

[0046] The quantum dot composition corresponding to the sub-pixel is used to form a film layer of the quantum dot composition on the surface of the substrate through a coating process.

[0047] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification, are used to explain the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0049] FIG1 is a schematic diagram of a process for preparing a quantum dot layer in one embodiment of the present disclosure.

[0050] FIG2 is a schematic structural diagram of a backplane having a pixel definition layer on its surface in one embodiment of the present disclosure.

[0051] FIG3 is a schematic structural diagram of a green quantum dot composition layer formed on the surface of a backplane in one embodiment of the present disclosure.

[0052] FIG4 is a schematic structural diagram of a green quantum dot layer formed on the surface of a backplane in one embodiment of the present disclosure.

[0053] FIG5 is a schematic structural diagram of a blue quantum dot composition layer formed on the surface of a backplane in one embodiment of the present disclosure.

[0054] FIG6 is a schematic structural diagram of a blue quantum dot layer formed on the surface of a backplane in one embodiment of the present disclosure.

[0055] FIG7 is a schematic structural diagram of a red quantum dot composition layer formed on the surface of a backplane in one embodiment of the present disclosure.

[0056] FIG8 is a schematic structural diagram of a red quantum dot layer formed on the surface of a backplane in one embodiment of the present disclosure.

[0057] FIG9 is a graph showing the UV excitation results of a glass substrate after coating, exposing, and developing the control quantum dot composition on the substrate.

[0058] FIG10 is a graph showing the UV excitation results of a glass substrate after coating, exposing, and developing the experimental quantum dot composition on the substrate. DETAILED DESCRIPTION

[0059] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure can be practiced without one or more of the specific details, or other methods, components, materials, etc. may be employed. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring the main technical ideas of the present disclosure.

[0060] The same reference numerals in the figures represent the same or similar structures, and thus their detailed description will be omitted. In addition, the drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0061] When a structure is “on” another structure, it may mean that the structure is integrally formed on the other structure, or that the structure is “directly” disposed on the other structure, or that the structure is “indirectly” disposed on the other structure via another structure.

[0062] The terms "a", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express open-ended inclusion and mean that additional elements / components / etc. may be present in addition to the listed elements / components / etc.; the terms "first", "second" and "third" etc. are used only as labels and are not intended to limit the quantity of their objects.

[0063] In related technologies, quantum dots are susceptible to heat and moisture, making them difficult to produce using the same vapor deposition method as self-luminous OLEDs. Instead, they can only be produced using inkjet printing. However, achieving high resolution with inkjet printing is difficult.

[0064] To solve the above problems, the embodiments of the present disclosure provide a quantum dot composition, which includes a quantum dot body, a ligand, and a cross-linking agent; the ligand is coordinated and connected to the quantum dot body; wherein one of the ligand and the cross-linking agent has a thiol group protected by a photolyzable group; the photolyzable group can be removed under light to release an active sulfur group, and the active sulfur group can react chemically with other components in the quantum dot composition to form a chemical bond. For example, the photolyzable group can release a thiol group, a thiol radical, or a thiol anion under light. When the released thiol group, thiol radical, or thiol anion is located on the cross-linking agent, the released thiol group, thiol radical, or thiol anion is used to coordinate and connect with the quantum dot body or to react with the ligand to form a chemical bond; when the released thiol group, thiol radical, or thiol anion is located on the ligand, the released thiol group, thiol radical, or thiol anion is used to react with the cross-linking agent to form a chemical bond.

[0065] In the quantum dot composition provided by the present disclosure, the quantum dot ligand or cross-linking agent contains a thiol group protected by a photoremovable protecting group (PPG). When the quantum dot composition is used, the photoremovable protecting group PPG can be removed under light conditions to release thiol groups, sulfhydryl radicals or sulfanyl anions. The released thiol groups, sulfhydryl radicals or sulfanyl anions can further react with other components in the quantum dot composition, so that the quantum dot body can form a quantum dot layer by cross-linking. For example, the thiol groups, sulfhydryl radicals or sulfanyl anions released on the cross-linking agent can be directly coordinated with the coordination center on the surface of the quantum dot body. For another example, the thiol groups, sulfhydryl radicals or sulfanyl anions released on the cross-linking agent can also react with the quantum dot ligand. For another example, the thiol groups, sulfhydryl radicals or sulfanyl anions released on the quantum dot ligand can react with the cross-linking agent. Therefore, the quantum dot composition of the present disclosure can be cross-linked under light, but no cross-linking occurs under non-light conditions, which allows the film layer prepared by the quantum dot composition to be patterned using a photolithography process. When a display panel uses the quantum dot composition disclosed herein and employs a photolithography process to prepare a quantum dot layer, the restriction of inkjet printing on resolution can be reduced, thereby facilitating improvement of the resolution of the display panel.

[0066] Quantum dots (QDs) are small-sized inorganic semiconductor nanoparticles, which are approximately or smaller than the exciton Bohr radius of the particle. Quantum dots are prone to agglomeration due to their small size and large specific surface area, and they have many surface defects. Therefore, when used, the surface of the quantum dots is usually modified with ligands to form modified quantum dots. In the embodiments of the present disclosure, the unmodified inorganic quantum dots are referred to as quantum dot bodies, and the materials modified on the quantum dot bodies are referred to as ligands. The ligands are generally organic ligands. The organic ligands not only play a protective role but also make the quantum dots have better solubility in the solution. The migration of carriers (electrons and holes) in quantum dots is confined to the interior of the quantum dots, which gives the quantum dots unique optical and electrical properties. Due to the unique size-dependent properties, the light absorption and luminescence properties of quantum dots can be easily adjusted by controlling the particle size, shape or surface structure.

[0067] The quantum dots of the present disclosure may be semiconductor nanocrystals and may have a variety of shapes. For example, they may be spherical, conical, multi-armed and / or cubic nanoparticles, nanotubes, nanowires, nanofibers, nanoplate particles, quantum rods, or quantum sheets. Here, the aspect ratio (length-to-diameter ratio; length: width ratio) of the quantum rod may be greater than about 1. For example, the aspect ratio of the quantum rod is greater than or equal to about 2, greater than or equal to about 3, or greater than or equal to about 5. For example, the quantum rod may have an aspect ratio of less than or equal to about 50, less than or equal to about 30, or less than or equal to about 20.

[0068] The quantum dot bodies can have, for example, a particle diameter (average maximum particle length for non-spherical shapes) of about 1 nm to about 100 nm, about 1 nm to about 80 nm, about 1 nm to about 50 nm, or about 1 nm to 20 nm, or 1 nm to 10 nm.

[0069] Exemplarily, the energy band gap of the quantum dot body can be controlled according to the size and composition of the quantum dot body, and thus the emission wavelength can be controlled. For example, when the size of the quantum dot body increases, the quantum dot body may have a narrow energy band gap and thus be configured to emit light in a relatively long wavelength region, and when the size of the quantum dot body decreases, the quantum dot body may have a wide energy band gap and thus be configured to emit light in a relatively short wavelength region. Exemplarily, the quantum dot body may be configured to emit light in a predetermined wavelength region in the visible light region according to its size and / or composition. For example, the quantum dot body may be configured to emit a second color light, a third color light, or a first color light, the second color light may have, for example, a peak emission wavelength (λ maximum) in a range of about 430 nm to about 480 nm, the third color light may have, for example, a peak emission wavelength (λ maximum) in a range of about 600 nm to about 650 nm, and the first color light may have, for example, a peak emission wavelength (λ maximum) in a range of about 520 nm to about 560 nm, but is not limited thereto.

[0070] Exemplarily, the average particle size of the quantum dot bodies configured to emit the second color light can be less than or equal to about 4.5 nm. For example, the average particle size of the quantum dot bodies configured to emit the second color light can be less than or equal to about 4.3 nm, less than or equal to about 4.2 nm, less than or equal to about 4.1 nm, or less than or equal to about 4.0 nm. Within this range, the average particle size of the quantum dot bodies can be about 2.0 nm to about 4.5 nm, for example, about 2.0 nm to about 4.3 nm, about 2.0 nm to about 4.2 nm, about 2.0 nm to about 4.1 nm, or about 2.0 nm to about 4.0 nm.

[0071] Exemplarily, the quantum dot body may have a quantum yield greater than or equal to about 10%, greater than or equal to about 20%, greater than or equal to about 30%, greater than or equal to about 50%, greater than or equal to about 60%, greater than or equal to about 70%, or greater than or equal to about 90%.

[0072] The quantum dot body may have a relatively narrow full width at half maximum (FWHM). Here, FWHM is the width corresponding to half the wavelength of the peak absorption point. When the FWHM is narrow, it can be configured to emit light in a narrow wavelength region and obtain higher color purity. For example, the quantum dot body can have a FWHM of less than or equal to about 50 nm, less than or equal to about 49 nm, less than or equal to about 48 nm, less than or equal to about 47 nm, less than or equal to about 46 nm, less than or equal to about 45 nm, less than or equal to about 44 nm, less than or equal to about 43 nm, less than or equal to about 42 nm, less than or equal to about 41 nm, less than or equal to about 40 nm, less than or equal to about 39 nm, less than or equal to about 38 nm, less than or equal to about 37 nm, less than or equal to about 36 nm, less than or equal to about 35 nm, less than or equal to about 34 nm, less than or equal to about 33 nm, less than or equal to about 32 nm, less than or equal to about 31 nm, less than or equal to about 30 nm, less than or equal to about 29 nm, or less than or equal to about 28 nm. Illustratively, within the range, it can have a FWHM of about 2 nm to about 49 nm, about 2 nm to about 48 nm, about 2 nm to about 47 nm, about 2 nm to about 46 nm, about 2 nm to about 45 nm, about 2 nm to about 44 nm, about 2 nm to about 43 nm, about 2 nm to about 42 nm, about 2 nm to about 41 nm, about 2 nm to about 40 nm, about 2 nm to about 39 nm, about 2 nm to about 38 nm, about 2 nm to about 37 nm, about 2 nm to about 36 nm, about 2 nm to about 35 nm, about 2 nm to about 34 nm, about 2 nm to about 33 nm, about 2 nm to about 32 nm, about 2 nm to about 31 nm, about 2 nm to about 30 nm, about 2 nm to about 29 nm, or about 2 nm to about 28 nm.

[0073] Exemplarily, the quantum dot body may include a II-VI semiconductor compound, a III-V semiconductor compound, a IV-VI semiconductor compound, a IV semiconductor, a I-III-VI semiconductor compound, a I-II-IV-VI semiconductor compound, a II-III-V semiconductor compound, or a combination thereof. For example, the II-VI semiconductor compound may be selected from: a binary semiconductor compound such as CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, or a mixture thereof; a ternary semiconductor compound such as CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, C dZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, or mixtures thereof; and quaternary semiconductor compounds such as HgZnTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, or mixtures thereof, but are not limited thereto. For another example, the III-V semiconductor compound may be selected from: binary semiconductor compounds such as GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, or mixtures thereof; ternary semiconductor compounds such as GaNPs, GaNAs, GaNSb, GaPAs, GaPSb, AlNPs, AlNAs, AlNSb, AlPAs, AlPSb, InNPs, InNAs, InNSb, InPAs, InPSb, or mixtures thereof; and quaternary semiconductor compounds such as GaAlNPs, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNPs, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNPs, InAlNAs, InAlNSb, InAlPAs, InAlPSb, or mixtures thereof, but are not limited thereto. For another example, the IV-VI semiconductor compound can be selected from: binary semiconductor compounds such as SnS, SnSe, SnTe, PbS, PbSe, PbTe, or a mixture thereof; ternary semiconductor compounds such as SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, or a mixture thereof; and quaternary semiconductor compounds such as SnPbSSe, SnPbSeTe, SnPbSTe, or a mixture thereof, but are not limited thereto.The Group IV semiconductor may be, for example, selected from: elemental (mono) semiconductors such as Si, Ge, or mixtures thereof; and binary semiconductor compounds such as SiC, SiGe, and mixtures thereof, but not limited thereto. The Group I-III-VI semiconductor compound may be, for example, CuInSe2, CuInS2, CuInGaSe, CuInGaS, or mixtures thereof, but not limited thereto. The Group I-II-IV-VI semiconductor compound may be, for example, CuZnSnSe, CuZnSnS, or mixtures thereof, but not limited thereto. The Group II-III-V semiconductor compound may include, for example, InZnP, but not limited thereto.

[0074] The quantum dot body may include the elemental semiconductor, the binary semiconductor compound, the ternary semiconductor compound, or the quaternary semiconductor compound in a substantially uniform concentration or in a locally different concentration distribution.

[0075] For example, the quantum dot body may include a cadmium (Cd)-free quantum dot body. A cadmium-free quantum dot body is a quantum dot body that does not include cadmium (Cd). Cadmium (Cd) can cause serious environmental / health issues and is an element restricted in many countries under the Restriction of Hazardous Substances (RoHS) directive.

[0076] Exemplarily, the quantum dot body may be a semiconductor compound including zinc (Zn), and at least one of tellurium (Te) and selenium (Se). For example, the quantum dot body may be a Zn-Te semiconductor compound, a Zn-Se semiconductor compound, and / or a Zn-Te-Se semiconductor compound. For example, the amount of tellurium (Te) in the Zn-Te-Se semiconductor compound may be less than the amount of selenium (Se). The semiconductor compound may have a peak emission wavelength (λ max) in a wavelength region less than or equal to about 480 nm, for example, about 430 nm to about 480 nm, and may be configured to emit a second color of light.

[0077] Exemplarily, the quantum dot body may be a semiconductor compound including indium (In), zinc (Zn), and phosphorus (P). For example, the quantum dot body may be an In-P semiconductor compound and / or an In-Zn-P semiconductor compound.

[0078] In the compound, a molar ratio of zinc (Zn) to indium (In) may be greater than or equal to about 25. The semiconductor compound may have a peak emission wavelength (λ max ) in a wavelength region less than about 700 nm, for example, about 600 nm to about 650 nm, and may be configured to emit a third color light.

[0079] The quantum dot body may have a core-shell structure. For example, the core and shell of the quantum dot body may have an interface, and an element of at least one of the core or the shell may have a concentration gradient at the interface, wherein the concentration of the shell element decreases toward the core. For example, the material composition of the shell of the quantum dot body has a higher energy band gap than the material composition of the core of the quantum dot body, and thus the quantum dot body may exhibit a quantum confinement effect.

[0080] The quantum dot body may have a quantum dot core and a multi-layer quantum dot shell surrounding the core. Here, the multi-layer shell has at least two shells, wherein each shell may be a single composition, an alloy, and / or have a concentration gradient.

[0081] For example, a shell of a multi-layer shell farther from the core may have a higher energy band gap than a shell closer to the core, and thus the quantum dot body may exhibit a quantum confinement effect.

[0082] For example, a quantum dot body having a core-shell structure may, for example, include: a core comprising a first semiconductor compound, the first semiconductor compound comprising zinc (Zn), and at least one of tellurium (Te) and selenium (Se); and a shell comprising a second semiconductor compound disposed on at least a portion of the core and having a composition different from the composition of the core.

[0083] For example, the first semiconductor compound may be a Zn-Te-Se based semiconductor compound including zinc (Zn), tellurium (Te) and selenium (Se), for example, a Zn-Se based semiconductor compound including a small amount of tellurium (Te), for example, a semiconductor compound represented by ZnTexSe1-x, where x is greater than about 0 and less than or equal to 0.05.

[0084] For example, in a first semiconductor compound based on Zn-Te-Se, the molar amount of zinc (Zn) may be higher than the molar amount of selenium (Se), and the molar amount of selenium (Se) may be higher than the molar amount of tellurium (Te). For example, in the first semiconductor compound, the molar ratio of tellurium (Te) to selenium (Se) may be less than or equal to about 0.05, less than or equal to about 0.049, less than or equal to about 0.048, less than or equal to about 0.047, less than or equal to about 0.045, less than or equal to about 0.044, less than or equal to about 0.043, less than or equal to about 0.042, less than or equal to about 0.041, less than or equal to about 0.04, less than or equal to about 0.039, less than or equal to about 0.035, less than or equal to about 0.03, less than or equal to about 0.04, or less than or equal to about 0.04. 29, less than or equal to about 0.025, less than or equal to about 0.024, less than or equal to about 0.023, less than or equal to about 0.022, less than or equal to about 0.021, less than or equal to about 0.02, less than or equal to about 0.019, less than or equal to about 0.018, less than or equal to about 0.017, less than or equal to about 0.016, less than or equal to about 0.015, less than or equal to about 0.014, less than or equal to about 0.013, less than or equal to about 0.012, less than or equal to about 0.011, or less than or equal to about 0.01. For example, in the first semiconductor compound, the molar ratio of tellurium (Te) to zinc (Zn) may be less than or equal to about 0.02, less than or equal to about 0.019, less than or equal to about 0.018, less than or equal to about 0.017, less than or equal to about 0.016, less than or equal to about 0.015, less than or equal to about 0.014, less than or equal to about 0.013, less than or equal to about 0.012, less than or equal to about 0.011, or less than or equal to about 0.010.

[0085] The second semiconductor compound may include, for example, a II-VI semiconductor compound, a III-V semiconductor compound, a IV-VI semiconductor compound, a Group IV semiconductor, a I-III-VI semiconductor compound, a I-II-IV-VI semiconductor compound, a II-III-V semiconductor compound, or a combination thereof. Examples of the II-VI semiconductor compound, the III-V semiconductor compound, the IV-VI semiconductor compound, the IV semiconductor, the I-III-VI semiconductor compound, the I-II-IV-VI semiconductor compound, and the II-III-V semiconductor compound are the same as described above.

[0086] For example, the second semiconductor compound may include zinc (Zn), selenium (Se), and / or sulfur (S). For example, the shell may include ZnSeS, ZnSe, ZnS, or a combination thereof. For example, the shell may include at least one inner shell disposed proximate to the core and an outermost shell disposed at the outermost side of the quantum dot body. The inner shell may include ZnSeS, ZnSe, or a combination thereof, and the outermost shell may include ZnS. For example, the shell may have a concentration gradient of one component, and, for example, the amount of sulfur (S) may increase as one moves away from the core.

[0087] For example, a quantum dot body having a core-shell structure may include: a core, the core including a third semiconductor compound, the third semiconductor compound including indium (In), and at least one of zinc (Zn) and phosphorus (P); and a shell disposed on at least a portion of the core and including a fourth semiconductor compound having a composition different from that of the core.

[0088] In the third In-Zn-P based semiconductor compound, a molar ratio of zinc (Zn) to indium (In) may be greater than or equal to about 25. For example, in the third In-Zn-P based semiconductor compound, the molar ratio of zinc (Zn) to indium (In) may be greater than or equal to about 28, greater than or equal to about 29, or greater than or equal to about 30. For example, in the third In-Zn-P based semiconductor compound, the molar ratio of zinc (Zn) to indium (In) may be less than or equal to about 55, for example, less than or equal to about 50, less than or equal to about 45, less than or equal to about 40, less than or equal to about 35, less than or equal to about 34, less than or equal to about 33, or less than or equal to about 32.

[0089] The fourth semiconductor compound may include, for example, a II-VI semiconductor compound, a III-V semiconductor compound, a IV-VI semiconductor compound, a Group IV semiconductor, a I-III-VI semiconductor compound, a I-II-IV-VI semiconductor compound, a II-III-V semiconductor compound, or a combination thereof. Examples of the II-VI semiconductor compound, the III-V semiconductor compound, the IV-VI semiconductor compound, the IV semiconductor, the I-III-VI semiconductor compound, the I-II-IV-VI semiconductor compound, and the II-III-V semiconductor compound are the same as described above.

[0090] For example, the fourth semiconductor compound may include zinc (Zn) and sulfur (S), and optionally selenium (Se). For example, the shell may include ZnSeS, ZnSe, ZnS, or a combination thereof. For example, the shell may include at least one inner shell disposed proximate to the core and an outermost shell disposed at the outermost side of the quantum dot body. At least one of the inner shell and the outermost shell may include the fourth semiconductor compound ZnS, ZnSe, or ZnSeS.

[0091] In this disclosure, for the sake of simplicity and clarity, the schematic diagrams of quantum dot bodies involved in the entire text are all represented by circles. The quantum dot body materials used in practice are not limited to spherical quantum dots, and include but are not limited to quantum dot materials of any geometric shape such as spherical, ellipsoidal, polyhedral, rod-shaped, cross-shaped, and ring-shaped.

[0092] In some embodiments of the present disclosure, the photolyzable group is selected from the following substituents:

[0093] Wherein, Ar1 is selected from an aryl group or a heteroaryl group having a nitro or hydroxyl group; R1, R2, and R3 are each independently selected from hydrogen, deuterium, or an alkyl group having 1 to 6 carbon atoms. represents a chemical bond. The photolyzable group can disintegrate under light to release a thiol group, a sulfhydryl radical, or a sulfhydryl ion.

[0094] In one embodiment of the present disclosure, the photolyzable group is selected from the following substituents:

[0095] Wherein, R5 is selected from hydrogen, deuterium, and alkoxy with 1 to 8 carbon atoms, for example, R5 is selected from hydrogen, deuterium, -OC n H 2n+1 (n=a positive integer of 1 to 8) In one example, R5 is selected from hydrogen, deuterium, methoxy, ethoxy, propoxy, isopropoxy, tert-butoxy, and the like.

[0096] It is understood that different photodegradable groups require different wavelengths of light (i.e., exposure wavelengths) for deprotection. For example, the exposure wavelength for PPG1 can be 320 nm or 365 nm; the exposure wavelength for PPG2 and PPG3 can be 254 nm; the exposure wavelength for PPG4 and PPG5 can be 365 nm; and the exposure wavelength for PPG6 can be 405 nm or 436 nm. The absorption wavelength and absorbance of the photodegradable group can also be adjusted by adding or removing substituents to the photodegradable group to accommodate a wider range of process flows.

[0097] In some embodiments of the present disclosure, the cross-linking agent has a plurality of thiol groups protected by photolyzable groups; that is, the cross-linking agent contains two or more thiol groups protected by photolyzable groups. The quantum dot ligand has an active alkenyl group, and the active alkenyl group includes an alkenyl group and an electron-withdrawing group connected to the alkenyl group. The cross-linking agent removes the protecting group (photolyzable group) under light and releases a thiol group, a sulfhydryl radical or a sulfhydryl anion, which can react with the alkenyl group in the active alkenyl group to form a chemical bond. In this way, at least part of the cross-linking agent is cross-linked with the ligands on different quantum dot bodies, so that the quantum dot bodies are interconnected.

[0098] In one example, multiple thiol groups protected by photolyzable groups can be linked via a first linking group. The first linking group can be a flexible segment or a rigid segment. Furthermore, the rigid segment can be a functional group that transports holes or electrons, or a conjugated group that facilitates hole and electron transport. For example, the rigid segment can include a triphenylamine-based structure, a carbazole-based structure, or a fluorene-based structure.

[0099] In a quantum dot layer using this quantum dot composition, the quantum dot bodies are interconnected via an organic material. This organic material includes a ligand group coordinated with the quantum dot bodies and a cross-linking group connected to multiple ligand groups, with a thioether structure formed between the ligand group and the cross-linking group. The ligands in the quantum dot composition react with released thiols, sulfhydryl radicals, or sulfhydryl anions to serve as ligand groups in the organic material. The first connecting group of the cross-linking agent can form a cross-linking group in the organic material, and the ligand group and the cross-linking group are connected via the thioether structure.

[0100] In one example, the structural formula of the quantum dot ligand is ABCD or ABD; wherein A is a coordination group capable of coordinating with the quantum dot body; B is a second connecting group; C is a carrier transport regulating group; and D is the active alkenyl group.

[0101] For example, the coordinating group can be selected from amino, carboxylic acid, thiol, dithiol, phosphino or phosphinooxy groups.

[0102] Exemplarily, the second linking group may be an alkyl chain containing 2-8 methylene groups, and the alkyl chain may be a linear alkyl chain or a branched alkyl chain.

[0103] Exemplarily, the carrier transport modulating group is selected from a triphenylamine-based structure or a carbazole-based structure. The carrier transport modulating group is incorporated into the quantum dot ligand to subsequently form a quantum dot layer with strong carrier transport capabilities. Triphenylamine-based and carbazole-based structures are beneficial for hole transport.

[0104] In one embodiment of the present disclosure, the activated alkenyl group is selected from the following groups:

[0105] Wherein, R4 is selected from hydrogen, deuterium, and an alkyl group having 1 to 6 carbon atoms; and EWG is an electron withdrawing group.

[0106] For example, the activated alkenyl group is selected from the following groups:

[0107] For example, a crosslinker containing two thiol groups protected by photolyzable groups can have the following reaction:

[0108] In the embodiment of the present disclosure, represents the skeleton structure of the cross-linker or ligand connected to the functional group (such as a thiol protected by a photolyzable group, a thiol, a thiol radical, a sulfhydryl anion, an active alkenyl group, etc.), for example, Represents the first linking group of the cross-linker or the non-functional part of the ligand. Represents the quantum dot itself.

[0109] In reaction formula (1), the structure of the cross-linking agent can be:

[0110] Optionally, the cross-linking agent can be synthesized by the following method:

[0111] 2-(1-Bromoethyl)-3-nitrodibenzofuran (0.64 g, 2 mmol) and ethyl mercaptoacetate (0.24 g, 2 mmol) were dissolved in 10 mL of dichloromethane. Zinc acetate (0.36 g, 2 mmol) was added, and the mixture was stirred at 25°C for 24 hours. 50 mL of saturated sodium chloride solution was then added to the reaction mixture, which was extracted three times with dichloromethane. After rotary evaporation and drying, the product was purified by column chromatography to obtain Intermediate 1 (0.47 g, 65% yield). 1 H NMRδ (ppm): 8.57(1H), 7.98(1H), 7.67(1H), 7,54(1H), 7.31-7.40(2H), 4.17(2H), 3.92(1H), 3.40(2H), 1.58(3H), 1.25(3H).

[0112] Intermediate 1 (0.36 g, 1 mmol) and sodium hydroxide (0.08 g, 2 mmol) were stirred in 10 mL of acetone at 40°C for 4 hours, cooled to room temperature, and then rotary evaporated to dryness. 50 mL of saturated sodium chloride solution was added, and the mixture was extracted three times with dichloromethane and then rotary evaporated to dryness. Purification by column chromatography and rotary evaporation to dryness gave Intermediate 2 (0.2 g, 60% yield). 1H NMRδ (ppm): 8.59 (1H), 7.97 (1H), 7.64 (1H), 7,56 (1H), 7.31-7.40 (2H), 3.90 (1H), 3.40 (2H), 1.58 (3H).

[0113] Intermediate 2 (0.166 g, 0.5 mmol) and ethylene glycol (12.4 mg, 0.2 mmol) were dissolved in 10 mL of dichloromethane. EDC (150 mg) (1-ethyl-(3-dimethylaminopropyl)carbodiimide) and DMAP (50 mg) (4-dimethylaminopyridine) were added. The mixture was stirred at 25°C for 12 hours, dried by rotary evaporation, and 50 mL of saturated sodium chloride solution was added. The mixture was extracted three times with dichloromethane and dried by rotary evaporation. Compound 3 (68.8 g, 50% yield) was obtained by column chromatography and rotary evaporation. 1 H NMRδ (ppm): 8.57(2H), 7.98(2H), 7.67(2H), 7,54(2H), 7.31-7.40(4H), 4.31(4H), 3.92(2H), 3.40(4H), 1.58(6H).

[0114] In reaction formula (1), the structure of the quantum dot ligand can be:

[0115] Wherein, the coordination group in the quantum dot ligand is a thiol group, and the second connecting group is The active alkenyl group is

[0116] In another example, the ligand in reaction formula (1) can also be:

[0117] Wherein, the coordination group in the quantum dot ligand is hydroxyl, and the second connecting group is The active alkenyl group is

[0118] In the above examples, the cross-linking agent having two reactive functional groups is used as an example for illustrative description. In the following, the cross-linking agent having three or more reactive functional groups is used as an example for illustrative description.

[0119] In one example, the reaction of the cross-linker with the ligand is as follows:

[0120] In this example, the crosslinker is:

[0121] The cross-linking agent can be synthesized by the following method:

[0122] Intermediate 2 (0.166 g, 0.5 mmol) and 2-hydroxymethyl-1,3-propanediol (16 mg, 0.15 mmol) were dissolved in 10 mL of dichloromethane, and EDC (150 mg) and DMAP (50 mg) were added. The mixture was stirred at 25°C for 12 hours, and then dried by rotary evaporation. 50 mL of saturated sodium chloride solution was added, and the mixture was extracted three times with dichloromethane and then dried by rotary evaporation. The product 4 was purified by column chromatography and dried by rotary evaporation to obtain product 4 (63 g, 40% yield). 1 H NMRδ (ppm): 8.57(3H), 7.98(3H), 7.67(3H), 7,54(3H), 7.31-7.40(6H), 4.31(6H), 3.92(3H), 3.40(6H), 1.58(9H), 1.21(1H).

[0123] In one example, the reaction of the cross-linker with the ligand is as follows:

[0124] In this example, the crosslinker is:

[0125] The cross-linking agent can be synthesized by the following method:

[0126] In another embodiment of the present disclosure, the quantum dot ligand has the thiol group protected by the photolyzable group; the cross-linking agent has a plurality of active alkenyl groups, and the active alkenyl groups include an alkenyl group and an electron-withdrawing group connected to the alkenyl group.

[0127] Optionally, the cross-linking agent has a first linking group, and the active alkenyl group is connected to the first linking group.

[0128] In a quantum dot layer using this quantum dot composition, the quantum dot bodies are interconnected via an organic material. The organic material includes a ligand group coordinated with the quantum dot body and a cross-linking group connected to multiple ligand groups, with a thioether structure formed between the ligand group and the cross-linking group. The cross-linking agent in the quantum dot composition reacts with the sulfhydryl group, sulfhydryl radical, or sulfhydryl anion on the ligand to form the cross-linking group of the organic material. The portion of the ligand in the quantum dot composition that is used to connect the sulfhydryl group, sulfhydryl radical, or sulfhydryl anion to the quantum dot body can form the ligand group of the organic material, and the ligand group and the cross-linking group are connected via the thioether structure.

[0129] Optionally, the structural formula of the quantum dot ligand is ABCD or ABD; wherein A is a coordination group capable of coordinating with the quantum dot body; B is a second connecting group; C is a carrier transport regulating group; and D is the thiol group protected by the photolyzable group.

[0130] In one example, the reaction between the cross-linker and the ligand is as follows:

[0131] In this example, the crosslinker is:

[0132] In this example, the ligand is:

[0133] The ligand can be synthesized by the following method:

[0134] In another example, the reaction of the cross-linker with the ligand is as follows:

[0135] Among them, exemplary cross-linking agents may be:

[0136] In another example, the reaction of the cross-linker with the ligand is as follows:

[0137] Among them, exemplary cross-linking agents may be:

[0138] In another embodiment, the crosslinking agent comprises a plurality of thiol groups protected by photolyzable groups; the mass ratio of the ligand in the quantum dot matrix and the ligand is no greater than 30%. In this embodiment, the thiol groups, sulfhydryl radicals, or sulfhydryl anions released by the crosslinking agent can directly bond with the quantum dot matrix, thereby crosslinking the quantum dot matrix.

[0139] In one example, in the quantum dot body and the ligand, the mass ratio of the ligand is no more than 15%.

[0140] In another example, in the quantum dot body and the ligand, the mass ratio of the ligand is between 15% and 30%; the acidity of the ligand is less than the acidity of the thiol group protected by the photolyzable group after deprotection.

[0141] In one example, the quantum dot ligand is selected from oleic acid, oleylamine, octanethiol, and dodecanethiol.

[0142] In another example, the crosslinker reacts directly with the quantum dot bulk after deprotection, as shown in the following reaction formula:

[0143] In one embodiment of the present disclosure, the mass content of the cross-linking agent is 1% to 5%. Of course, the amount of the cross-linking agent can be increased or decreased as needed.

[0144] In one embodiment of the present disclosure, the quantum dot composition further includes a solvent, such as PGMEA (propylene glycol methyl ether acetate) or toluene, hexane, octane, or a combination thereof. In one example, the concentration of the quantum dots is 10 to 100 mg / mL.

[0145] The disclosed embodiments also validated the crosslinking ability of quantum dot compositions under illumination. Specifically, an experimental quantum dot composition containing a crosslinker and a control quantum dot composition without a crosslinker were provided. The structures of the crosslinker and ligand are as follows, respectively, and the quantum dot matrix is ​​red.

[0146] A layer of hole-transport material, which can be excited to emit blue light when exposed to ultraviolet light, was first coated on a glass substrate. A control quantum dot composition was then coated on the surface of the hole-transport material layer and exposed and developed. After development, the glass substrate was exposed to ultraviolet light. As shown in Figure 9, the surface of the glass substrate appears blue. This indicates that the glass substrate surface is devoid of red quantum dot bodies and that the control quantum dot composition has not been cross-linked.

[0147] A layer of hole-transport material, which can be excited to emit blue light when exposed to ultraviolet light, was first coated on a glass substrate. The experimental quantum dot composition was then coated on the surface of the hole-transport material layer and exposed and developed. After development, the glass substrate was exposed to ultraviolet light. (See Figure 10) The surface of the glass substrate appears red. This indicates that the red quantum dots are fixed to the surface of the hole-transport material layer and that the experimental quantum dot composition has undergone cross-linking.

[0148] The present disclosure also provides a light-emitting element, which includes a quantum dot layer; the quantum dot layer has quantum dot bodies interconnected by an organic material;

[0149] The organic material includes a ligand group coordinated with the quantum dot body and a cross-linking group connected to multiple ligand groups, and a thioether structure is formed between the ligand group and the cross-linking group; or, the organic material has multiple thiol groups, thiol radicals or thiol anions and is coordinated with multiple quantum dot bodies through thiol groups, thiol radicals or thiol anions.

[0150] Optionally, a quantum dot solution having the quantum dot composition provided by the embodiments of the present disclosure may be patterned by light irradiation to form a quantum dot layer of a light-emitting element.

[0151] The present disclosure also provides a method for preparing a display panel, comprising: sequentially forming quantum dot layers of at least two sub-pixels on the surface of a substrate through a photolithography process; for example, sequentially forming three quantum dot layers, namely a red quantum dot layer, a green quantum dot layer, and a blue quantum dot layer.

[0152] 1 , forming a quantum dot layer of any of the sub-pixels includes:

[0153] Step S110, forming a quantum dot composition film layer on the surface of the substrate using the quantum dot composition corresponding to the sub-pixel, wherein the quantum dot composition is selected from the above-mentioned quantum dot composition;

[0154] Step S120 , exposing and developing the quantum dot composition film layer corresponding to the sub-pixel to obtain the quantum dot layer of the sub-pixel.

[0155] The quantum dot layers of different sub-pixels contain different quantum dots in the quantum dot composition. For example, when preparing a red quantum dot layer, the quantum dot composition contains red quantum dots. When preparing a green quantum dot layer, the quantum dot composition contains green quantum dots. When preparing a blue quantum dot layer, the quantum dot composition contains blue quantum dots.

[0156] In one embodiment of the present disclosure, the method for preparing the display panel further includes:

[0157] Before forming the quantum dot layer, a hole transport layer is formed for each of the sub-pixels.

[0158] In one embodiment of the present disclosure, the method for preparing the display panel further includes:

[0159] After forming the quantum dot layer of each sub-pixel, an electron transport layer of each sub-pixel is formed.

[0160] In one embodiment of the present disclosure, forming a quantum dot composition film layer on the surface of the substrate using the quantum dot composition corresponding to the sub-pixel includes:

[0161] The quantum dot composition corresponding to the sub-pixel is used to form a film layer of the quantum dot composition on the surface of the substrate through a coating process.

[0162] As follows, the method for forming various quantum layers according to the embodiment of the present disclosure is exemplarily described with reference to the accompanying drawings.

[0163] Step S210 , preparing three quantum dot solutions of different colors, wherein the quantum dot solutions contain quantum dot compositions of different colors and solvents thereof.

[0164] For example, when preparing a red quantum dot solution, red quantum dot bodies are used. When preparing a green quantum dot solution, green quantum dot bodies are used. When preparing a blue quantum dot solution, blue quantum dot bodies are used.

[0165] The following exemplary method can be used to prepare any quantum dot solution: dissolve ligand-modified quantum dot bodies (CdSe / ZnSe quantum dots) in a solvent (e.g., n-octane or PGMEA) to a concentration of 30 mg / mL. Add the desired crosslinker to the quantum dot solution.

[0166] In step S220, a green quantum dot solution is applied to the substrate, followed by exposure to ultraviolet light using a first mask. After exposure, the substrate is rinsed and developed using PGMEA or toluene as a developer. After development, the substrate is heated at 90°C for 120 seconds to remove the developer, resulting in a patterned green quantum dot layer.

[0167] In step S230, a blue quantum dot solution is applied to the substrate, followed by exposure to ultraviolet light using a second mask. After exposure, the substrate is rinsed and developed using PGMEA or toluene as a developer. After development, the substrate is heated at 90°C for 120 seconds to remove the developer, resulting in a patterned blue quantum dot layer.

[0168] In step S240, a red quantum dot solution is applied to the substrate, and a third mask is applied to expose the entire surface to ultraviolet light. After exposure, PGMEA or toluene is used as a developer for rinsing and development. After development, the substrate is heated at 90°C for 120 seconds to remove the developer, resulting in a patterned red quantum dot layer.

[0169] In steps S220 to S240, the green, blue, and red quantum dot solutions are patterned using the first, second, and third masks, respectively, to produce a patterned green, blue, and red quantum dot layer. By controlling the light-transmitting areas of the first, second, and third masks, the positions and shapes of the three different quantum dot layers can be controlled.

[0170] As follows, a method for manufacturing a display panel provided by an embodiment of the present disclosure is exemplarily described with reference to the accompanying drawings.

[0171] Step S310, see Figure 2, provide a backplane BP. Optionally, the backplane BP includes a base substrate and a driving layer stacked in sequence, and the driving layer has a transistor layer and a source and drain metal layer. Starting from the base substrate, the various film layers of the driving layer can be prepared in sequence, for example, a gate layer (for example, a material of molybdenum with a thickness of 200nm), a gate insulating layer (for example, a 150nm thick silicon oxide), a semiconductor layer (for example, a material of IGZO with a thickness of 40nm), a source and drain metal layer (for example, a material of molybdenum with a thickness of 200nm), and a passivation layer (for example, a 300nm silicon oxide) are prepared in sequence.

[0172] Furthermore, a pixel electrode layer (for example, made of ITO with a thickness of 40 nm) and a pixel definition layer PDL (for example, acrylic with a thickness of 1.5 microns) may be formed in sequence on the backplane.

[0173] In step S320, the back plate surface is first cleaned, for example, by using plasma to treat the surface of the driving back plate.

[0174] In step S330, a first common material layer is formed on the surface of the backplane, such as a hole injection layer and a hole transport layer for each sub-pixel. In one example, the hole injection layer and the hole transport layer can be formed using a spin coating process, such as spin coating PEDOT:PSS (hole injection layer) and TFB (hole transport layer), respectively. Furthermore, the combined thickness of the hole injection layer and the hole transport layer is 50-100 nm.

[0175] In step S340 (see Figures 3 and 4), a green quantum dot layer (GQDL) is formed on the surface of the backplane (BP). For example, a green quantum dot solution is applied to the backplane to form a green quantum dot composition layer (G1). A first mask is then applied and the entire layer is exposed to UV light. After exposure, PGMEA or toluene is used as a developer for rinsing and development. After development, the backplane is heated at 90°C for 120 seconds to remove the developer, resulting in a patterned green quantum dot layer (GQDL).

[0176] In step S350 (see Figures 5 and 6), a blue quantum dot layer (BQDL) is formed on the surface of the backplane (BP). For example, a blue quantum dot solution is applied to the backplane to form a blue quantum dot composition layer (B1). A second mask is then applied and the entire layer is exposed to UV light. After exposure, PGMEA or toluene is used as a developer for rinsing and development. After development, the backplane is heated at 90°C for 120 seconds to remove the developer, resulting in a patterned blue quantum dot layer (BQDL).

[0177] In step S360 (see Figures 7 and 8), a red quantum dot layer RQDL is formed on the surface of the backplane BP. For example, a red quantum dot solution is applied to the backplane to form a red quantum dot composition layer R1. A third mask is then applied and the entire layer is exposed to UV light. After exposure, PGMEA or toluene is used as a developer for rinsing and development. After development, the backplane is heated at 90°C for 120 seconds to remove the developer, resulting in a patterned red quantum dot layer RQDL.

[0178] Step S370: After forming each quantum dot layer, a second common material layer is prepared. The second common material layer includes, but is not limited to, an electron transport layer (such as ZnO nanoparticles) and an electron injection layer. The second common material layer can be formed by spin coating or evaporation.

[0179] Step S380: forming a cathode, for example, by evaporating a thin cathode metal layer, such as an Al layer, with a thickness of about 500-1000 nm.

[0180] After the evaporation is completed, packaging and cutting are carried out to complete the preparation of the entire AMQLED display panel.

[0181] In one example, the prepared display panel is a bottom-illuminated display panel.

[0182] In one example, the minimum size of a sub-pixel may be in the range of 10 to 30 micrometers, which enables the resolution of the display panel to reach 300 to 800 PPI.

[0183] Optionally, when preparing a display panel, there may be a gap between the quantum dot layers of two adjacent sub-pixels, or the layers may overlap with each other.

[0184] In one example, when preparing a display panel, the quantum dot layer is located within a pixel opening formed by a pixel definition layer.

[0185] In another example, when preparing the display panel, at least a portion of the edge of the quantum dot layer is located outside the pixel opening formed by the pixel definition layer.

[0186] In other embodiments of the present disclosure, the quantum dot bodies in the aforementioned quantum dot composition can also be replaced with nanoparticles such as ZnO, ZnMgO, ZnAlO, and ZnLiO to form an electron transport material composition, which can be formed into an electron transport layer using a photolithography process. Of course, when the electron transport layer does not require patterning, the film formed by the electron transport material composition can be cured by light irradiation.

[0187] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the appended claims.

Claims

1. A quantum dot composition comprising a quantum dot body, a ligand, and a cross-linking agent; The ligand is coordinated and connected with the quantum dot body; in, One of the ligand and the cross-linker has a thiol group protected by a photolyzable group; The photolyzable group can be removed under light to release a sulfhydryl group, a sulfhydryl radical or a sulfhydryl anion; When the released thiol group, thiol free radical or thiol anion is located on the cross-linking agent, the released thiol group, thiol free radical or thiol anion is used to coordinate with the quantum dot body or to react with the ligand to form a chemical bond; when the released thiol group, thiol free radical or thiol anion is located on the ligand, the released thiol group, thiol free radical or thiol anion is used to react with the cross-linking agent to form a chemical bond.

2. The quantum dot composition according to claim 1, wherein The photolyzable group is selected from the following substituents: Wherein, Ar1 is selected from an aryl group having a nitro group or a hydroxyl group, or a heteroaryl group having a nitro group or a hydroxyl group; R1, R2 and R3 are each independently selected from hydrogen, deuterium, or an alkyl group having 1 to 6 carbon atoms.

3. The quantum dot composition according to claim 2, wherein The photolyzable group is selected from the following substituents: Wherein, R5 is selected from hydrogen, deuterium, and an alkoxy group having 1 to 8 carbon atoms.

4. The quantum dot composition according to claim 1, wherein The cross-linking agent has a plurality of thiol groups protected by photolyzable groups; the ligand has an active alkenyl group, and the active alkenyl group includes an alkenyl group and an electron-withdrawing group connected to the alkenyl group.

5. The quantum dot composition according to claim 4, wherein The cross-linking agent has a first linking group, and the thiol group protected by the photolyzable group is linked to the first linking group.

6. The quantum dot composition according to claim 4, wherein The structural formula of the ligand is ABCD or ABD; wherein A is a coordination group capable of coordinating with the quantum dot; B is a second connecting group; C is a carrier transport regulating group; and D is the active alkenyl group.

7. The quantum dot composition according to claim 1, wherein The ligand has the thiol group protected by the photolyzable group; the cross-linking agent has a plurality of active alkenyl groups, and the active alkenyl groups include an alkenyl group and an electron-withdrawing group connected to the alkenyl group.

8. The quantum dot composition according to claim 7, wherein The cross-linking agent has a first linking group, and the reactive alkenyl group is linked to the first linking group.

9. The quantum dot composition according to claim 7, wherein The structural formula of the ligand is ABCD or ABD; wherein A is a coordination group capable of coordinating with the quantum dot; B is a second connecting group; C is a carrier transport regulating group; and D is the thiol protected by the photolyzable group.

10. The quantum dot composition according to claim 6 or 9, wherein The coordination group has an amino group, a carboxylic acid group, a thiol group, two thiol groups, a phosphine group or a phosphineoxy group.

11. The quantum dot composition according to claim 4 or 7, wherein The active alkenyl group is selected from the following groups: Wherein, R4 is selected from hydrogen, deuterium, and an alkyl group having 1 to 6 carbon atoms; and EWG is an electron withdrawing group.

12. The quantum dot composition according to claim 11, wherein The active alkenyl group is selected from the following groups:

13. The quantum dot composition according to claim 1, wherein The cross-linking agent has a plurality of thiol groups protected by photolyzable groups; In the quantum dot body and the ligand, the mass ratio of the ligand is no more than 30%.

14. The quantum dot composition according to claim 13, wherein In the quantum dot body and the ligand, the mass ratio of the ligand is no more than 15%.

15. The quantum dot composition according to claim 13, wherein In the quantum dot body and the ligand, the mass ratio of the ligand is between 15% and 30%; The acidity of the ligand is less than the acidity of the thiol group protected by the photolyzable group after the protecting group is removed.

16. The quantum dot composition according to claim 13, wherein The ligand is selected from oleic acid, oleylamine, octanethiol, and dodecanethiol.

17. The quantum dot composition according to any one of claims 1 to 9, wherein The mass content of the cross-linking agent is 1% to 5%.

18. A light emitting element, wherein: The light emitting element includes a quantum dot layer; the quantum dot layer has quantum dot bodies interconnected by organic materials; The organic material includes a ligand group coordinated with the quantum dot body and a cross-linking group connected to multiple ligand groups, and a thioether structure is formed between the ligand group and the cross-linking group; or, the organic material has multiple thiol groups, thiol radicals or thiol anions and is coordinated with multiple quantum dot bodies through thiol groups, thiol radicals or thiol anions.

19. A display panel, wherein: The light-emitting element according to claim 18 is included.

20. A method for preparing a display panel, comprising: On the surface of the substrate, quantum dot layers of at least two sub-pixels are formed sequentially by photolithography; Forming any one of the quantum dot layers of the sub-pixels includes: Forming a quantum dot composition film layer on the surface of the substrate using the quantum dot composition corresponding to the sub-pixel, wherein the quantum dot composition is selected from the quantum dot composition according to any one of claims 1 to 18; Expose and develop the quantum dot composition film layer corresponding to the sub-pixel to obtain the sub-pixel quantum dot layer; The quantum dot layers of different sub-pixels contain different quantum dots in the quantum dot compositions.

21. The method for manufacturing a display panel according to claim 20, wherein: The method for preparing the display panel further includes: Before forming the quantum dot layer, a hole transport layer is formed for each of the sub-pixels.

22. The method for manufacturing a display panel according to claim 20, wherein: The method for preparing the display panel further includes: After forming the quantum dot layer of each sub-pixel, an electron transport layer of each sub-pixel is formed.

23. The method for manufacturing a display panel according to claim 20, wherein: The step of forming a quantum dot composition film layer on the surface of the substrate using the quantum dot composition corresponding to the sub-pixels comprises: The quantum dot composition corresponding to the sub-pixel is used to form a film layer of the quantum dot composition on the surface of the substrate through a coating process.

Images