Quantum dot material, light-emitting device and preparation method therefor

Abstract

Provided in the embodiments of the present disclosure are a quantum dot material, a light-emitting device, and a preparation method for the light-emitting device, relating to the technical field of displays. The quantum dot material comprises: a quantum dot body and a functional material. The functional material comprises an aromatic amine group and a solubilizing group. The solubilizing group is used for increasing the solubility of the functional material in a preset solvent. The ratio of the mass of the functional material to the mass of the quantum dot body is greater than 0 and less than or equal to 0.45. The cross-linked quantum dot material formed by the quantum dot material is used as a light-emitting layer material of the light-emitting device.

Description

Quantum dot material, light emitting device and preparation method thereof

[0001] This application claims priority to Chinese Patent Application No. 202411001880.4, filed on July 24, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

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

[0003] 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 wavelength, long service life, etc., and have become a research hotspot of new type 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 of new type display devices. SUMMARY

[0004] In one aspect, a quantum dot material is provided. The quantum dot material includes a quantum dot body and a functional material. The functional material contains an aromatic amine group and a cosolvent group. The cosolvent group is used to increase the solubility of the functional material in a predetermined solvent, and the ratio between the mass of the functional material and the mass of the quantum dot body is greater than 0 and less than or equal to 0.45.

[0005] In some embodiments, the predetermined solvent contains an ether group and / or an ester group.

[0006] In some embodiments, the functional material includes a first functional material. The first functional material contains a first aromatic amine group and a cosolvent group. The first functional material is not connected to the quantum dot body.

[0007] In some embodiments, the ratio between the mass of the first functional material and the mass of the quantum dot body ranges from 0 to 0.35.

[0008] In some embodiments, the functional material includes a second functional material. The second functional material contains a second aromatic amine group, a second coordination group and a cosolvent group. The second functional material can be coordinated to the quantum dot body.

[0009] In some embodiments, the second coordination group includes a carboxyl group and / or a mercapto group.

[0010] In some embodiments, the second functional material further contains a second photosensitive group.

[0011] In some embodiments, the quantum dot material further comprises a first ligand material. The first ligand material comprises a first photosensitive group. The first ligand material can be ligated to the quantum dot body.

[0012] In some embodiments, in the case that the second functional material comprises a second photosensitive group, the second photosensitive group comprises one or a combination of any multiple of an alkenyl group, an alkynyl group, a benzophenone group, and an azido group. In the case that the quantum dot material comprises a first ligand material, the first photosensitive group comprises one or a combination of any multiple of an alkenyl group, an alkynyl group, a benzophenone group, and an azido group.

[0013] In some embodiments, in the case that the quantum dot material comprises a first ligand material, a ratio between a mass of the first ligand material and a mass of the quantum dot body is greater than 0 and less than or equal to 0.45. In the case that the quantum dot material comprises a first ligand material and a second functional material, a ratio between a mass of the first ligand material and a mass of the second functional material, and a mass of the quantum dot body is greater than 0 and less than or equal to 0.45.

[0014] In some embodiments, the functional material comprises a third functional material. The third functional material comprises a third aromatic amine group, at least two initiating groups, and a cosolvent group. In the case that the quantum dot material comprises a first ligand material, the initiating group is configured to react with the first photosensitive group under light irradiation, causing the quantum dot material to form a crosslinked quantum dot material. In the case that the quantum dot material comprises a second functional material, and the second functional material comprises a second photosensitive group, the initiating group is configured to react with the second photosensitive group under light irradiation, causing the quantum dot material to form a crosslinked quantum dot material. Wherein, a solubility of the crosslinked quantum dot material in a predetermined solvent is less than a solubility of the quantum dot material in the predetermined solvent.

[0015] In some embodiments, the initiating group comprises a thiol group.

[0016] In some embodiments, a ratio between a mass of the third functional material and a mass of the quantum dot body ranges from 0 to 0.05.

[0017] In some embodiments, the functional material is selected from any one of the following structures of general formula (I);

[0018] wherein R1and R2are the same or different, and are each independently selected from any one of a substituted or unsubstituted C1-C10 alkylene, a substituted or unsubstituted C1-C10 alkyleneoxy, a substituted or unsubstituted C3-C10 cycloalkylene, a substituted or unsubstituted C1-C10 heterocycloalkylene, a substituted or unsubstituted C6-C12 arylene, a substituted or unsubstituted C1-C12 heteroarylene, and a group comprising the cosmotonic group. R3-R8are the same or different, and are each independently selected from any one of hydrogen, deuterium, a substituted or unsubstituted C1-C10 alkyl, a substituted or unsubstituted C1-C10 alkoxy, a substituted or unsubstituted C3-C10 cycloalkyl, a substituted or unsubstituted C1-C10 heterocycloalkyl, a substituted or unsubstituted C6-C12 aryl, a substituted or unsubstituted C1-C12 heteroaryl, and a group comprising the cosmotonic group. Any two of n1, n2, m1, and m2are the same or different, and are each independently selected from any one of 0, 1, and 2, and the sum of n1and m1is 2, the sum of n2and m2is 2, and at least one of n1and n2is not 0.

[0019] In the case where the functional material is the first functional material, at least one of X and R1-R8comprises the cosmotonic group. In the case where the functional material is the second functional material, X is a second coordination group, and at least one of R1-R8comprises the cosmotonic group. In the case where the functional material is the third functional material, the sum of n1and n2is greater than or equal to 2, X is an initiating group, and at least one of R1-R8comprises the cosmotonic group.

[0020] In some embodiments, the functional material is selected from any one of the structures shown in the following general formula (II);

[0021] wherein R9is selected from any one of a substituted or unsubstituted C1-C10 alkylene, a substituted or unsubstituted C1-C10 alkyleneoxy, a substituted or unsubstituted C3-C10 cycloalkylene, a substituted or unsubstituted C1-C10 heterocycloalkylene, a substituted or unsubstituted C6-C12 arylene, a substituted or unsubstituted C1-C12 heteroarylene, and a group comprising the cosmotonic group. p is selected from any one of 0, 1, and 2. q is selected from any one of 1, 2, and 3, and the sum of p and q is 3.

[0022] In the case where the functional material is the first functional material, at least one of X and R9comprises the cosmotonic group. In the case where the functional material is the second functional material, X is a second coordination group, and R9comprises the cosmotonic group. In the case where the functional material is the third functional material, q is greater than or equal to 2, X is an initiating group, and at least one of R9comprises the cosmotonic group.

[0023] In some embodiments, the cosolubilizing group comprises an ester group and / or an ether group.

[0024] In another aspect, a light emitting device is provided. The light emitting device comprises an anode, a cathode, and a light emitting layer. The anode and the cathode are oppositely disposed. The light emitting layer is located between the anode and the cathode. A material of the light emitting layer comprises a crosslinked quantum dot material formed by a quantum dot material of the above-mentioned embodiments.

[0025] In some embodiments, the light emitting device is disposed on a substrate. The cathode is closer to the substrate than the anode.

[0026] In some embodiments, the light emitting device further comprises an electron transport layer. The electron transport layer is located between the cathode and the light emitting layer, and in contact with the light emitting layer.

[0027] In another aspect, a method for manufacturing a light emitting device is provided. The method comprises forming a cathode, an anode, and a light emitting layer. The cathode and the anode are oppositely disposed. The light emitting layer is located between the anode and the cathode. A material of the light emitting layer comprises a crosslinked quantum dot material formed by a quantum dot material. The quantum dot material comprises a quantum dot body and a functional material. The functional material comprises an aromatic amine group and a cosolubilizing group. The cosolubilizing group is used to increase the solubility of the functional material in a predetermined solvent. A ratio between a mass of the functional material and a mass of the quantum dot body is greater than 0 and less than or equal to 0.45.

[0028] In some embodiments, the light emitting device is formed on a substrate. Forming the light emitting layer comprises: spin-coating a material of an initial light emitting layer on a side of the cathode distal to the substrate to form an initial light emitting layer. The material of the initial light emitting layer comprises the quantum dot material and the predetermined solvent. Exposing a target region of the initial light emitting layer to cause a material of a portion of the initial light emitting layer exposed to be converted into the crosslinked quantum dot material. And developing the initial light emitting layer using a developing solution. The developing solution comprises the predetermined solvent.

[0029] In some embodiments, the material of the initial light emitting layer comprises: mixing the quantum dot body, an initial ligand material, and the predetermined solvent to form a quantum dot stock solution. A ratio between a mass of the initial ligand material and a mass of the quantum dot body is greater than 0 and less than or equal to 0.13. The initial ligand material comprises a first ligand material. The first ligand material is ligatable to the quantum dot body. The first ligand material comprises a first photosensitive group. Alternatively, the initial ligand material comprises a second functional material. The second functional material is ligatable to the quantum dot body. The second functional material comprises a second photosensitive group. The functional material comprises the second functional material. Alternatively, the initial ligand material comprises the first ligand material and the second functional material. The first ligand material and the second functional material are ligatable to the quantum dot body. The first ligand material comprises the first photosensitive group. The functional material comprises the second functional material.

[0030] In some embodiments, the material forming the initial light-emitting layer further comprises adding a first supplemental ligand material in the quantum dot stock solution. The ratio between the mass of the first supplemental ligand material and the mass of the quantum dot bulk ranges from 0 to 0.35. In the case that the initial ligand material comprises the first ligand material, the first supplemental ligand material comprises the first ligand material. In the case that the initial ligand material comprises the second functional material, the first supplemental ligand material comprises the second functional material.

[0031] In some embodiments, the material of the initial light-emitting layer and / or the developing solution further comprises a first functional material. The functional material comprises the first functional material. The first functional material is not connected to the quantum dot bulk.

[0032] In some embodiments, the material of the initial light-emitting layer further comprises a third functional material. The functional material comprises the third functional material. The third functional material comprises at least two initiating groups. In the case that the quantum dot material comprises the first ligand material, the initiating groups are configured to react with the first photosensitive group under light to form a cross-linked quantum dot material. In the case that the quantum dot material comprises the second functional material, and the second functional material comprises a second photosensitive group, the initiating groups are configured to react with the second photosensitive group under light to form a cross-linked quantum dot material.

[0033] In some embodiments, the developing solution further comprises a second supplemental ligand material. The ratio between the mass of the second supplemental ligand material in the developing solution and the mass of the quantum dot bulk in the material of the initial light-emitting layer ranges from 0 to 0.1. In the case that the initial ligand material comprises the first ligand material, the second supplemental ligand material comprises the first ligand material. In the case that the initial ligand material comprises the second functional material, the second supplemental ligand material comprises the second functional material. BRIEF DESCRIPTION OF DRAWINGS

[0034] 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 time sequence, etc. of the product involved in the embodiments of the present disclosure.

[0035] FIG. 1 is a structural diagram of a display panel according to some embodiments;

[0036] FIG. 2A is a structural diagram of a display panel according to yet some embodiments;

[0037] FIG. 2B is a structural diagram of a display panel according to yet some embodiments;

[0038] FIG. 3 is a diagram of forming steps of a light-emitting layer according to some embodiments;

[0039] FIG. 4 is a diagram of forming steps of a light-emitting layer according to yet some embodiments;

[0040] FIG. 5 is a diagram of forming steps of a light-emitting layer according to yet some embodiments;

[0041] FIG. 6 is a diagram of cross-linking of quantum dot material according to some embodiments;

[0042] FIG. 7 is a diagram of a structure of a light-emitting device according to some embodiments;

[0043] FIG. 8 is a diagram of a preparation flow of a light-emitting device according to some embodiments;

[0044] FIG. 9 is a diagram of preparation steps of a light-emitting layer according to some embodiments;

[0045] FIG. 10 is a diagram of a thermogravimetric test of a quantum dot stock solution according to some embodiments;

[0046] FIG. 11 is a diagram of a structure of a light-emitting device according to yet some embodiments;

[0047] FIG. 12 is a diagram of photoluminescence of quantum dot material according to some embodiments;

[0048] FIG. 13 is a scanning electron microscope (SEM) image of developed quantum dot material according to some embodiments;

[0049] FIG. 14 is a diagram of photoluminescence of quantum dot material according to yet some embodiments. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings. It should be apparent that the described embodiments are only a part of the embodiments of the present disclosure, and not all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by those of ordinary skill in the art are within the scope of protection of the present disclosure.

[0051] Unless the context clearly requires otherwise, throughout the description and the claims, the term "comprise," and variations thereof (e.g., "comprises" and "comprising"), will be construed to be inclusive in a manner consistent with the term's plain meaning, namely, "including but not limited to." In describing the description, the terms "one embodiment," "some embodiments," "exemplary embodiments," "example," "specific example" or "some examples," and the like, mean that a particular feature, structure, material, or characteristic is included in at least one embodiment or example of the disclosure, but that it can not be included in other embodiments or examples. The illustrative appearance of the foregoing terms in various places in the description are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0052] Hereinafter, the terms "first", "second", etc. are used only for the purpose of description and should not be construed as indicating or implying relative importance or implying the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the disclosure, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0053] In describing some embodiments, "coupled" and "connected," and variations thereof, can be used. The term "connected" should be interpreted broadly, for example, "connected" can be fixedly connected, or detachably connected, or integrated; can be directly connected, or indirectly connected through an intermediate medium. The term "coupled" indicates, for example, that two or more components have direct physical contact or electrical contact. The term "coupled" or "communicatively coupled" can also mean that two or more components do not have direct contact with each other, but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the content herein.

[0054] "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.

[0055] "A and / or B" includes the following three combinations: only A, only B, and a combination of A and B.

[0056] As used herein, "about," "approximately," or "around" includes the recited value and the average value within an acceptable range of deviation from the particular value, as determined by 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).

[0057] As used herein, "parallel," "perpendicular," "equal" includes the recited condition and conditions that approximate the recited condition, the approximation being within an acceptable range of deviation, 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). For example, "parallel" includes absolute parallel and near parallel, where the acceptable range of deviation for near parallel can be, for example, within 5°; "perpendicular" includes absolute perpendicular and near perpendicular, where the acceptable range of deviation for near perpendicular can also be, for example, within 5°. "Equal" includes absolute equality and near equality, where the acceptable range of deviation for near equality can be, for example, a difference between the two that is less than or equal to 5% of either.

[0058] It will be understood that when a layer or element is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening layers can also be present.

[0059] Exemplary embodiments are described herein with reference to cross-sectional and / or plan view illustrations that are idealized examples of exemplary embodiments. In the drawings, the thickness of layers and regions are exaggerated for clarity. Accordingly, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are to be expected. Thus, the exemplary embodiments should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an etched region illustrated as a rectangle will typically have rounded or curved features. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region of a device and are not intended to limit the scope of the exemplary embodiments.

[0060] As shown in FIG. 1, some embodiments of the present disclosure provide a display panel 200 including a plurality of light emitting devices 100 and a plurality of pixel driving circuits 231.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] In some examples, the driving circuit layer 230 includes cathodes and anodes in a longitudinal and transverse cross pattern, 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).

[0068] 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 been more and more widely concerned due to its potential advantages in wide color gamut, long life and the like, and the quantum efficiency is constantly improved, basically reaching the level of industrialization.

[0069] 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. It should be understood that the encapsulation layer 240 can encapsulate the light emitting device 100 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 display panel 200 to be shortened.

[0070] Exemplarily, 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 in the direction away from the substrate 210.

[0071] In some embodiments, as shown in FIG. 1, in the display panel 200, the light emitting functional layer 220 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 by one corresponding to the plurality of openings Q.

[0072] The display panel 200 can be a QLED display panel, and the light-emitting device 100 can be a QLED light-emitting device. Based on the quantum confinement effect, quantum dots (QDs) have excellent light-emitting properties such as wide-band absorption, narrow-band emission, and continuous adjustable peak position. Meanwhile, quantum dots have solution processability, which avoids the use of expensive vacuum equipment, so that the quantum dot light-emitting diode (QLED) using quantum dots as light-emitting materials can be a new type of light-emitting diode (LED) with the advantages of high color purity, high light-emitting quantum efficiency, adjustable light-emitting wavelength, and high photoluminescence quantum yield. It is considered to be a strong competitor of the next generation of display and solid-state lighting technology, and is widely used in display lighting, solar cells, and photoelectric detection fields, for example, in new display devices (electrochromic or photoluminescent) with wide color gamut and high resolution.

[0073] In some embodiments, as shown in FIG. 7, the light-emitting device 100 includes an anode 15, a cathode 11, and a light-emitting layer 13. The anode 15 and the cathode 11 are oppositely arranged. The light-emitting layer 13 is located between the anode 15 and the cathode 11.

[0074] For example, as shown in FIG. 7, the anode 15, the light-emitting layer 13, and the cathode 11 can be stacked along a first direction X, and the first direction X intersects a second direction Y. For example, the second direction Y is perpendicular to the first direction X.

[0075] Based on the above structure, the light-emitting principle of the light-emitting device 100 is that the anode 15 injects holes into the light-emitting layer 13, and the cathode 11 injects electrons into the light-emitting layer 13 by using a circuit (for example, a pixel driving circuit 231, as shown in FIG. 1) connected by the anode 15 and the cathode 11. The injected electrons and holes form excitons (i.e., electron-hole pairs) in the light-emitting layer 13. The excitons transition back to the ground state by radiation, and emit photons.

[0076] For example, in order to ensure that the light-emitting device 100 can effectively emit light, the anode 15 can be made of a material with a high work function, so that the holes in the anode 15 can effectively migrate into the light-emitting layer 13 under the drive of an electric field, and then recombine with the electrons from the cathode 11 to emit light. The material of the anode 15 can be a transparent conductive metal oxide material, for example, the material of the anode 15 can be indium tin oxide (ITO), indium zinc oxide (IZO), or the like. Alternatively, the anode 15 can be a composite electrode containing multiple materials, for example, the material of the anode 15 can be ITO / Ag / ITO, Ag / IZO, CNT / ITO, CNT / IZO, GO / ITO, or GO / IZO, and the like, where Ag is silver, CNT is a carbon nanotube, and GO is graphene oxide.

[0077] In some examples, the cathode 11 can be made of a material with a low work function, so that the electrons in the cathode 11 can more easily inject into the electron transport unit 12, and thus the electrons in the cathode 11 can effectively migrate into the light-emitting layer 13 under the drive of an electric field, and then recombine with the holes in the anode 15 to emit light. The material of the cathode 11 can be a metal material, a metal oxide, or a metal alloy, for example, aluminum (Al), silver (Ag), gold (Au), magnesium (Mg), calcium (Ca), ytterbium (Yb), indium (In), lithium (Li), potassium (K), sodium (Na), tin (Sn), titanium (Ti), lead (Pb), samarium (Sm), yttrium (Y), indium tin oxide (ITO), magnesium-silver alloy (Mg:Ag), ytterbium-gold alloy (Yb:Au), ytterbium-silver alloy (Yb:Ag), lithium-aluminum alloy (Li:Al), lithium-calcium-magnesium alloy (Li:Ca:Al), or the like. Alternatively, the material of the cathode 11 can be a laminated material, for example, magnesium / aluminum (Mg / Al), magnesium / silver (Mg / Ag), aluminum / silver (Al / Ag), aluminum / gold (Al / Au), ytterbium / gold (Yb / Au), ytterbium / silver (Yb / Ag), calcium / magnesium (Ca / Mg), calcium / silver (Ca / Ag), barium / silver (Ba / Ag), or the like.

[0078] In some embodiments, as shown in FIG. 7, in order to improve the light-emitting efficiency of the light-emitting device 100, the light-emitting device 100 further includes a hole transport unit 14 located on the side of the light-emitting layer 13 close to the anode 15 and in contact with the light-emitting layer 13. The hole transport unit 14 includes at least one of a hole injection layer (HIL), a hole transport layer (HTL), and an electron blocking layer (EBL) arranged in layers, for example.

[0079] In some embodiments, as shown in FIG. 7, to improve the light-emitting efficiency of the light-emitting device 100, the light-emitting device 100 further comprises an electron transport unit 12 located on the side of the light-emitting layer 13 close to the cathode 11 and in contact with the light-emitting layer 13. The electron transport unit 12, for example, comprises at least one of an electron injection layer (EIL), an electron transport layer (ETL), and a hole blocking layer (EBL) arranged in layers.

[0080] By arranging the hole transport unit 14 and the electron transport unit 12, a transition step is formed between the anode 15 and the light-emitting layer 13 and between the cathode 11 and the light-emitting layer 13, which reduces the height of the potential barrier that the carriers need to overcome, resulting in higher light-emitting efficiency.

[0081] Exemplarily, the material of the hole transport layer can be poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butyphenyl) diphenylamine)] (TFB).

[0082] Exemplarily, the material of the hole injection layer can be poly(3,4-ethylenedioxythiophene) (PEDOT).

[0083] In some embodiments, as shown in FIG. 7, to improve the light-emitting efficiency of the light-emitting device 100, the light-emitting device 100 comprises an electron transport layer.

[0084] Exemplarily, the material of the electron transport layer can be zinc oxide or magnesium zinc oxide.

[0085] In the preparation method of the QLED light-emitting device, the patterning process of the light-emitting layer 13 (see FIG. 7) is a key process step for realizing high-resolution full-color QLED display, which can be realized by a photolithography process. The photolithography process, i.e., a process for realizing quantum dot patterning by exposure and development, includes indirect photolithography and direct photolithography.

[0086] The indirect photolithography process needs the participation of photoresist and sometimes needs the assistance of a sacrificial layer for peeling, which has some problems in actual application: on the one hand, harsh developing conditions can damage the formed light-emitting layer, affecting the efficiency of the light-emitting device; on the other hand, when preparing a QLED display panel that can realize full-color display, the photoresist (and the sacrificial layer) will be repeatedly applied, resulting in a complex entire process, which is not conducive to industrial production.

[0087] In contrast, the principle of the direct lithography process is, for example, to connect ligand materials with photosensitive properties to the surface of the quantum dot body, to match the development process to achieve the patterning of the target region of the light-emitting layer by using the feature that the solubility of these ligand materials in the solvent is strongly affected by light (for example: decomposition, cross-linking or desorption, etc.). For example, based on the photosensitive properties of these ligand materials, photochemical reactions occur between the ligand materials and the ligand materials, or between the ligand materials and the cross-linking materials, under the influence of light during exposure, thereby changing the solubility of the quantum dot material in the solvent, forming cross-linked quantum dot materials with lower solubility, and then removing the quantum dot materials in the non-target region that is not exposed by development, so that the target region can form a specific pattern of the light-emitting layer of the QLED light-emitting device. In other words, the quantum dot material can have the effect of negative photoetching, that is, the quantum dot material will become insoluble in the developing solution after exposure because of the cross-linking of the cross-linked quantum dot material, so it will not be washed away by the developing solution, thereby remaining after development, achieving the purpose of patterning the light-emitting layer. When the direct lithography process is used to form the light-emitting layer, the damage to the film quality during the preparation process of the light-emitting device can be reduced, and the patterning process can be simplified.

[0088] Based on the above-mentioned direct lithography process, in some embodiments, the material of the light-emitting layer 13 includes cross-linked quantum dot materials formed by quantum dot materials.

[0089] Illustratively, the quantum dot material includes quantum dot light-emitting materials and cross-linking materials; wherein the quantum dot light-emitting material includes quantum dot bodies and ligand materials arranged on the quantum dot bodies. The cross-linking material can be configured to cross-link with the ligand material under the condition of light radiation to generate cross-linked quantum dot materials. Through the above-mentioned arrangement, the light-emitting layer of the QLED light-emitting device can be formed by the lithography process.

[0090] In some implementations, the electron mobility and the hole mobility in the light-emitting layer of the QLED light-emitting device are relatively imbalanced, resulting in a decrease in the efficiency of the light-emitting device. As one possible reason, when the light-emitting layer is formed by the lithography process, the carrier transport performance of some cross-linking material molecules is relatively poor, and the chain segments of these cross-linking agent molecules can remain in the cross-linked quantum dot material, which can hinder the carrier transport of the material of the light-emitting layer. As another possible reason, the carrier transport performance of each film layer material is different, which can make the carrier mobility in the light-emitting layer imbalanced.

[0091] To this end, in some embodiments, the electron mobility and the hole mobility of the material of the quantum dot light-emitting layer are balanced by adding a material with good carrier transport performance in the quantum dot light-emitting layer, so as to improve the efficiency and service life of the QLED light-emitting device. For example, the hole injection in the quantum dot light-emitting layer is usually more difficult than the electron injection, and therefore, a compound with strong electron-donating ability can be added in the quantum dot light-emitting layer, because the hole mobility of such a compound is generally high, which can improve the exciton recombination characteristics of the quantum dot light-emitting layer, so as to balance the electron mobility and the hole mobility in the quantum dot light-emitting layer. Illustratively, a small-molecule hole transport material, carbazole derivative 4,4',4"-tris(9-carbazolyl)triphenylamine (TCTA), can be added in the quantum dot light-emitting layer. The nitrogen atom on the TCTA has strong electron-donating ability, has enhanced π-π interaction, has good conjugation, and has high hole mobility, which can help to increase the hole amount in the light-emitting layer, improve the exciton recombination characteristics of the light-emitting layer, and balance the electron and hole mobilities in the quantum dot light-emitting layer. When the amount of TCTA added is 10% by weight, the energy level structure of the hole transport layer and the quantum dot light-emitting layer can be effectively adjusted, the balance between the holes and the electrons injected into the light-emitting layer can be achieved, and the device efficiency can be improved.

[0092] In some implementations, due to the structural limitations of the added material with good carrier transport performance, the solubility of the material in a solution (which can be understood as a quantum dot solution) for forming a light-emitting layer is small, and the material with good carrier transport performance is difficult to form a uniform system when added to the quantum dot solution, which makes it difficult to participate in film formation and affects the balance between the electron mobility and the hole mobility in the light-emitting layer.

[0093] In yet some implementations, when a direct lithography method is used to prepare a light-emitting layer of a QLED light-emitting device, during development, the quantum dot material and the material of a functional layer (hereinafter referred to as a front film layer) adjacent to the light-emitting layer are affected by intermolecular interaction forces, so that part of the quantum dot material remains in a non-target area after development, so that multiple colors of light-emitting materials exist in one sub-pixel area, causing color crosstalk and color mixing problems, such as red / green / blue color mixing problems, which eventually leads to a decrease in the color gamut and a decrease in the photoelectric performance of the QLED display panel. For example, when the front film layer is an electron transport layer, the material of the electron transport layer (for example, zinc oxide / magnesium zinc oxide) can anchor part of the quantum dot material, resulting in poor development effect.

[0094] Based on this, some embodiments of the present disclosure provide a quantum dot material. As shown in FIGS. 3-5 and 7, the quantum dot material includes a quantum dot body and a functional material. The functional material contains an aromatic amine group and a cosolvent group. The cosolvent group is used to increase the solubility of the functional material in a predetermined solvent, and the ratio between the mass of the functional material and the mass of the quantum dot body is greater than 0 and less than or equal to 0.45.

[0095] Exemplarily, the preset solvent can be a solvent of the quantum dot solution.

[0096] In some examples, the quantum dot body can include any combination of one or more of: a II-VI quantum dot, a III-V quantum dot, a IV-VI quantum dot, a IV quantum dot, a I-III-VI quantum dot, a I-II-IV-VI quantum dot, a core-shell quantum dot, and an ABX3 type perovskite quantum dot.

[0097] The II-VI quantum dot can be selected from one or more of: a binary compound such as CdS, CdSe, CdTe, ZnS, ZnO, ZnSe, ZnTe, HgSe, HgTe, and HgS; a ternary compound such as HgxCd1-xTe, HgxCd1-xS, HgxCd1-xSe, HgxZn1-xTe, CdxZn1-xSe, CdxZn1-xS, and ZnTeSe, where 0 < x < 1, but is not limited thereto.

[0098] The III-V quantum dot can be selected from InP, InAs, InSb, GaAs, GaP, GaN, GaSb, GaNk, InN, AlP, AlN, AlAs, InGaAs, InGaN, or a mixture thereof; but is not limited thereto.

[0099] The IV-VI quantum dot can be selected from PbS, PbSe, PbTe, or a mixture thereof; but is not limited thereto.

[0100] The core-shell quantum dot refers to a quantum dot in which one material is a core and another material is a shell. For example, a quantum dot of CdS@ZnS refers to a quantum dot in which the material of the core is CdS and the material of the shell is ZnS. The core-shell quantum dot 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 Cd1-xZnxS@ZnS, where 0 < x < 1, but is not limited thereto.

[0101] In the ABX3 type perovskite quantum dot, A can be one or more of CH3NH3+(methylamine), NH2CH=NH2(formamidine), and Cs+, B can be one or both of Pb2+and Sn2+, and X can be one or more of Cl-, Br-, and I-. The ABX3 type perovskite quantum dot can include CH3NH3PbBr3, CH3NH3PbCl3, CH3NH3PbI3, CsPbBr3, CsPbCl3, and CsPbI3, but is not limited thereto.

[0102] When the plurality of quantum dots are combined, the quantum dot body can be an alloy material, for example, one of CsPbCl3 / ZnS, CsPbBr3 / ZnS, CsPbI3 / ZnS, CdS / ZnSeS / ZnS, CdSe / ZnSeS / ZnS, ZnSe / ZnSeS / ZnS, and ZnSeTe / ZnSeS / ZnS.

[0103] In some examples, the aromatic amine group can be an aromatic group containing a nitrogen-containing substituent, in which case the nitrogen element can not be an atom on the ring of the aromatic amine group; for example, the aromatic amine group can be a group corresponding to an aromatic amine derivative from which one or more atoms (such as H) have been removed.

[0104] In yet other examples, the aromatic amine group can be a nitrogen-containing heteroaromatic group, in which case the nitrogen element can be an atom on the ring of the aromatic amine group; for example, a group corresponding to a carbazole derivative from which one or more atoms (such as H) have been removed, or a group corresponding to a pyrroline derivative from which one or more atoms (such as H) have been removed.

[0105] Exemplarily, the mass of the functional material can be measured by a method such as a nuclear magnetic resonance (NMR) method, a Fourier transform infrared spectroscopy (FT-IR) method, and the like, to obtain a ratio between the mass of the functional material and the mass of the quantum dot body.

[0106] Exemplarily, the ratio between the mass of the functional material and the mass of the quantum dot body can be 0.09, 0.18, 0.27, 0.35, or 0.45, and the like.

[0107] Here, the connection relationship between the functional material and the quantum dot body is not limited. For example, the functional material can include a functional material that can be coordinately connected to the quantum dot body, and / or a functional material that is not connected to the quantum dot body.

[0108] By the above arrangement, when the quantum dot material is used to prepare the light-emitting layer 13 of the QLED light-emitting device, in a first aspect, the use of the aromatic amine group can improve the carrier transport performance of the light-emitting layer 13. Specifically, the nitrogen atom in the aromatic amine group has strong electron-donating ability, strong π-π interaction, and good conjugation, so that the functional material has high hole mobility. In a second aspect, the auxiliary solubilizing group of the functional material can improve the solubility of the functional material in the predetermined solvent, so that the functional material exists in the quantum dot solution in the form of being free or being bonded to the quantum dot body. On the one hand, the quantum dot body and the functional material can form a uniform and stable quantum dot solution, so that the functional material can participate in film formation, which is conducive to the balanced electron mobility and hole mobility of the functional material. On the other hand, the intermolecular interaction between any two of the quantum dot body, the ligand material, and the pre-film layer material can be weakened, so that the quantum dot material is prevented from being left on the surface of the pre-film layer after development, thereby solving the color crosstalk problem. Here, the ligand material is, for example, the first ligand material and / or the second functional material described in detail below.

[0109] Furthermore, when the ratio between the mass of the functional material and the mass of the quantum dot body in the quantum dot material is large (for example, greater than 0.45), the functional material around the quantum dot body in the quantum dot material of the light-emitting layer 13 is more, which can cause the light emission of the light-emitting layer 13 to be discontinuous and hinder the light emission performance of the quantum dot body. Therefore, by setting the ratio between the mass of the functional material and the mass of the quantum dot body to be greater than 0 and less than or equal to 0.45, the electron mobility and the hole mobility in the light-emitting layer 13 can be balanced on the basis of ensuring the continuity of the light emission of the light-emitting layer 13, so that the light-emitting efficiency of the light-emitting device 100 is improved.

[0110] In some embodiments, the predetermined solvent contains an ether group and / or an ester group.

[0111] In some examples, the predetermined solvent can be a solvent in the quantum dot solution, and / or a developing solution in the photolithography process.

[0112] Illustratively, the predetermined solvent can be propylene glycol methyl ether acetate (PGMEA). It should be understood that PGMEA is an environmentally friendly solvent, so that the use of the predetermined solvent can reduce the impact on the environment, and when PGMEA is used as a developing solution, the damage to the light-emitting layer 13 and the carrier transport functional layer (for example, the film layer in the hole transport unit 14 and / or the electron transport unit 12 shown in FIG. 7) is small, and the damage can be substantially avoided.

[0113] It can be understood that, by virtue of the pre-set solvent containing ether groups and / or ester groups, the solubility of the quantum dot material in the quantum dot solution can be improved, the concentration of the quantum dot material in the quantum dot solution can be increased, the content of the quantum dot body in the formed light-emitting layer 13 (see FIG. 7) can be increased to some extent, and the light-emitting efficiency can be improved. Moreover, the solvent containing ether groups and / or ester groups generally has low toxicity and low volatility, and the pre-set solvent can have less impact on the environment.

[0114] In some embodiments, the solubilizing group comprises an ester group.

[0115] It can be understood that the ester group has strong polarity and can form strong interaction between the pre-set solvent (for example, PGMEA) molecules, so that the solubility of the functional material in the pre-set solvent is increased, the content of the functional material in the quantum dot solution is increased, and the effect of preventing the quantum dot body from remaining on the surface of the front film layer is improved.

[0116] In some embodiments, the solubilizing group comprises an ether group.

[0117] It can be understood that the ether group has good compatibility with the organic solvent and can form strong interaction with the pre-set solvent (for example, PGMEA), and the content of the functional material in the quantum dot solution can be increased as described in the foregoing part.

[0118] For example, the functional groups (for example, ester groups and / or ether groups) contained in the functional material can be qualitatively or quantitatively measured by nuclear magnetic resonance (NMR) method, Fourier transform infrared spectroscopy (FT-IR) method, and the like.

[0119] In some embodiments, as shown in FIG. 3, the functional material comprises a first functional material. The first functional material comprises a first aromatic amine group and a solubilizing group. The first functional material is not connected to the quantum dot body.

[0120] Here, the number of the solubilizing groups contained in the first functional material is not limited. For example, as shown in formula (a) and formula (d) described below, the first functional material can comprise one solubilizing group; for another example, as shown in formula (a1), formula (s), and formula (g) described below, the first functional material can comprise two solubilizing groups.

[0121] It should be understood that, when the first functional material is not connected to the quantum dot body, the first functional material is neither connected to the quantum dot body through a chemical bond nor connected to the quantum dot body through a coordination bond. That is, the first functional material can be distributed around the quantum dot body in a free manner.

[0122] It can be understood that, in the first aspect, the solubilizing group can increase the solubility of the first functional material in the preset solvent, so that the first functional material and the quantum dot body form a uniform and stable system; in the second aspect, when the first functional material is distributed around the quantum dot body in a free manner, a physical barrier effect can be formed, which can increase the spacing between the quantum dot body and the front film layer material, weaken the anchoring effect of the front film layer (for example, the electron transport layer) on the quantum dot body, and increase the spacing between the quantum dot bodies, in other words, the first functional material can act as a dispersant for the quantum dot body, and can inhibit the agglomeration of the quantum dot body, so that the adsorption between the quantum dot body and the front film layer material can be reduced, and the quantum dot body can be prevented from remaining on the surface of the front film layer, so that the development effect can be improved.

[0123] In some embodiments, the ratio between the mass of the first functional material and the mass of the quantum dot body ranges from 0 to 0.35.

[0124] For example, the ratio between the mass of the first functional material and the mass of the quantum dot body can be 0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 or 0.35, etc. It should be understood that the ratio between the mass of the first functional material and the mass of the quantum dot body can be 0, that is, the first functional material can not be included in the quantum dot material.

[0125] It can be understood that when the ratio between the mass of the first functional material and the mass of the quantum dot body is large (for example, greater than 0.35), the spacing between the quantum dot bodies can be too large, which can affect the light emission continuity of the light-emitting layer; therefore, by setting the ratio between the mass of the first functional material and the mass of the quantum dot body to range from 0 to 0.35, the amount of the first functional material in the quantum dot material can be within a suitable range, which can prevent the quantum dot material from remaining on the surface of the front film layer on the basis of ensuring the light emission continuity of the light-emitting layer.

[0126] As described above, the quantum dot material can further include a ligand material configured to the quantum dot body, and the ligand material is at least configured to prevent the agglomeration of the quantum dot body to stabilize the quantum dot solution. Hereinafter, the content of the type of the ligand material in the quantum dot material will be exemplarily described.

[0127] In some embodiments, as shown in FIG. 4, the functional material includes a second functional material. The second functional material includes a second aromatic amine group, a second coordination group and a solubilizing group. The second functional material can be configured to the quantum dot body.

[0128] Here, the number of the second coordination group included in the second functional material is not limited.

[0129] For example, as shown in formula (b1) described below, the second functional material can include one second coordinating group.

[0130] Here, the second functional material can be coordinated to the quantum dot body, meaning that the surface atoms or groups of the quantum dot body can interact with the coordinating group in the second functional material based on shared electrons or electron transfer between atoms or molecules to form a coordination bond. When the coordination bond is formed, the second functional material can be attached to the surface of the quantum dot body, and can hinder the agglomeration of the quantum dot bodies by forming a hindering effect and / or passivating surface defects of the quantum dot body, thereby making the quantum dot body more stable.

[0131] It can be understood that the auxiliary solubilizing group can increase the solubility of the second functional material in the predetermined solvent, so that the second functional material forms a uniform and stable system with the quantum dot body. Moreover, by using the second coordinating group, a coordination bond can be formed between the second functional material and the quantum dot body, so that at least part of the second functional material can be connected to the quantum dot body to form a quantum dot system with double-ligand bonding. Among them, the part of the second functional material coordinated to the quantum dot body can act as a ligand material to passivate surface defects of the quantum dot body and reduce agglomeration of the quantum dot body; the part of the second functional material not coordinated to the quantum dot body can act as a dispersant and exist in free form around the quantum dot body, which can increase the spacing between the quantum dot body and the front film layer material and between the quantum dot bodies; in this way, the quantum dot body can be prevented from remaining on the surface of the front film layer.

[0132] It should be understood that, in the case where the quantum dot material includes the second functional material, the quantum dot material can or can not include the first functional material, which is not limited here. Moreover, in the case where the quantum dot material includes the first functional material and the second functional material, the second aromatic amine group and the first aromatic amine group can or can not be the same, which is not limited here.

[0133] In some embodiments, the second coordinating group is one or more of any combination of a hydroxyl group, a phosphoric acid group, and an amino group.

[0134] In some embodiments, the second coordinating group includes a carboxyl group and / or a mercapto group.

[0135] For example, the carboxyl group and / or the mercapto group included in the second functional material can be qualitatively or quantitatively measured by methods such as nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR).

[0136] It can be understood that the carboxyl group and / or the mercapto group has strong electrophilicity, can be coordinated with the quantum dot body to form a relatively stable coordination bond structure, so that the second functional material can be coordinated on the quantum dot body.

[0137] In some examples, when the quantum dot material includes the first functional material, the process step of forming the cross-linked quantum dot material of the light-emitting layer by using the quantum dot material is shown in FIG. 3. When the quantum dot material includes the second functional material, the process step of forming the cross-linked quantum dot material of the light-emitting layer by using the quantum dot material is shown in FIG. 4. In FIG. 3 and FIG. 4, when exposed, the quantum dot material of the target area is selectively exposed by using a mask plate or a mask layer. Here, the exposure light can include two specific wavelengths of light λ1 / λ2 (for example, λ1=365 nm, λ2=405 nm). During the exposure process, the photosensitive group will undergo a photochemical reaction under light to form a cross-linked quantum dot material, and the solubility of the cross-linked part in the predetermined solvent is reduced. Here, the photosensitive group is a photosensitive reaction group / function group, which is at least configured to undergo a cross-linking reaction under light.

[0138] The following illustrates the existence form of the photosensitive group in the quantum dot material.

[0139] In some embodiments, the second functional material further includes a second photosensitive group.

[0140] Here, for understanding of the second photosensitive group, reference can be made to the aforementioned exemplary description of the photosensitive group, which will not be repeated here.

[0141] It can be understood that when the second functional material includes the second photosensitive group, the second functional material has photosensitivity and can act as a photosensitive ligand of the quantum dot body. In this way, the second functional material connected to one quantum dot body can directly undergo a cross-linking reaction with the second functional material connected to another quantum dot body under light, or indirectly undergo a cross-linking reaction through a cross-linking material to form a stable three-dimensional network structure to form a cross-linked quantum dot material. The cross-linked quantum dot material will remain in the target area after development to achieve the purpose of patterning the target area.

[0142] It should be understood that when the quantum dot material includes the second functional material and the second functional material includes the second photosensitive group, the ligand material of the quantum dot body can only include the second functional material.

[0143] In some examples, the ligand material of the quantum dot body further includes other ligand materials in addition to the second functional material.

[0144] In some embodiments, the quantum dot material further includes a first ligand material. The first ligand material includes a first photosensitive group. The first ligand material can be coordinated on the quantum dot body.

[0145] It should be understood that when the first ligand material can be coordinated to the quantum dot body, the first ligand material comprises a coordination group that can be coordinated to the quantum dot body, such as one or more of any combination of a carboxyl group, a hydroxyl group, a phosphoric acid group, and an amino group.

[0146] Here, for the understanding of the first photosensitive group, reference can be made to the foregoing exemplary description of the photosensitive group, which will not be repeated here.

[0147] Exemplarily, the first ligand material can be one or more of a combination of succinic acid mono[2-[(2-methyl-acryloyl)oxy]ethyl] ester (MMES) and 4-(2-(acryloyloxy)ethoxy)-4-oxobutanoic acid. Among them, the MMES molecule comprises a carbon-carbon double bond group, an ester group, and a carboxyl group, etc., which can act as an X-type ligand of the quantum dot body, and the carboxyl group on the MMES forms a coordination bond with each metal cation on the quantum dot, so that the coordination of the MMES and the quantum dot body is facilitated.

[0148] It should be understood that in the case where the quantum dot material comprises the first ligand material, the quantum dot material can or can not comprise the first functional material; and the quantum dot material can or can not comprise the second functional material, which is not limited here.

[0149] It can be understood that by providing the quantum dot material comprising the first ligand material, on the one hand, the first ligand material can be coordinated to the quantum dot body through the coordination bond, which can increase the spacing between the quantum dot bodies and ensure good dispersibility of the quantum dot bodies; on the other hand, by providing the first ligand material comprising the first photosensitive group, the quantum dot material can undergo cross-linking reaction under light conditions, so that the quantum dot material can form a cross-linked quantum dot material to achieve the purpose of selective patterning.

[0150] In some examples, the quantum dot material comprises the quantum dot body and the first ligand material, and at this time, under light conditions, the first photosensitive group contained in the first ligand material can undergo self-crosslinking reaction, or cross-linking reaction with the cross-linking material, and the first ligand material can ensure the cross-linking effect of the quantum dot material.

[0151] In yet other examples, the quantum dot material comprises the quantum dot body, the first ligand material, and the second functional material, and the second functional material does not comprise a photosensitive group, and at this time, under light conditions, the first photosensitive group contained in the first ligand material can undergo self-crosslinking reaction, or cross-linking reaction with the cross-linking material, and the first ligand material can ensure the cross-linking effect of the quantum dot material.

[0152] In yet other examples, the quantum dot material includes quantum dot bodies, a first ligand material, and a second functional material, the second functional material further includes a second photosensitive group. In this case, under light irradiation, a self-crosslinking reaction can occur between the first photosensitive groups, between the second photosensitive groups, and between the first photosensitive groups and the second photosensitive groups, or a crosslinking reaction can occur between the first photosensitive groups and a crosslinking material, and between the second photosensitive groups and the crosslinking material, and the first ligand material and the second functional material can ensure the crosslinking effect of the quantum dot material.

[0153] In some embodiments, in the case where the second functional material includes a second photosensitive group, the second photosensitive group includes one or a combination of any multiple of an alkenyl group, an alkynyl group, a benzophenone group, and an azido group.

[0154] In some embodiments, in the case where the quantum dot material includes a first ligand material, the first photosensitive group includes one or a combination of any multiple of an alkenyl group, an alkynyl group, a benzophenone group, and an azido group.

[0155] It should be understood that the alkenyl group includes an unsaturated carbon-carbon double bond, and the alkynyl group includes an unsaturated carbon-carbon triple bond. When the first photosensitive group and / or the second photosensitive group includes an alkenyl group or an alkynyl group, under light irradiation, a self-crosslinking reaction (e.g., an addition reaction) can occur between the alkenyl groups, between the alkynyl groups, or between the alkenyl groups and the alkynyl groups, or a crosslinking reaction can occur between the alkenyl groups and a crosslinking material or between the alkynyl groups and the crosslinking material, so as to form a crosslinked quantum dot material.

[0156] For example, when the first photosensitive group and / or the second photosensitive group includes an alkenyl group, the alkenyl group connected to one quantum dot body can undergo an addition reaction with the alkenyl group connected to another quantum dot body, so as to connect the one quantum dot body to the another quantum dot body, thereby forming a crosslinked quantum dot material. For another example, when the first photosensitive group and / or the second photosensitive group includes an alkenyl group, the alkenyl group connected to one quantum dot body can undergo an addition reaction with a first part of a crosslinking material, and the alkenyl group connected to another quantum dot body can undergo an addition reaction with a second part of the crosslinking material, so as to connect the one quantum dot body to the another quantum dot body through the crosslinking material, thereby forming a crosslinked quantum dot material.

[0157] It should be understood that the benzophenone group can photolyze to generate a triplet ketone intermediate under light irradiation (hv), the structure of which is shown in the following formula, and the C ● -O ● of the triplet ketone intermediate can attack a nearby C-H bond to undergo a crosslinking reaction, so as to form a crosslinked quantum dot material.

[0158] For example, when the first and / or second photosensitive groups contain benzophenone groups, in the quantum dot material, the benzophenone groups attached to one quantum dot matrix can undergo a hydrocarbon insertion reaction with a ligand material (e.g., a second functional material and / or a first ligand material) attached to another quantum dot matrix, thereby connecting one quantum dot matrix to another, thus forming a cross-linked quantum dot material. As another example, when the first and / or second photosensitive groups contain benzophenone groups, the benzophenone groups attached to one quantum dot matrix can undergo a hydrocarbon insertion reaction with the first portion of the cross-linked material; the benzophenone groups attached to another quantum dot matrix can undergo a hydrocarbon insertion reaction with the second portion of the cross-linked material, thereby connecting one quantum dot matrix to another through the cross-linked material, thus forming a cross-linked quantum dot material.

[0159] It should be understood that the azide group can be photolyzed under light conditions to generate the reactive intermediate free radical nitrogen carbene. Nitrogen carbene attacks nearby CH bonds to induce a cross-linking reaction, causing the quantum dot material to form a cross-linked quantum dot material.

[0160] For example, when the first and / or second photosensitive groups contain azide groups, the azide groups attached to one quantum dot matrix can undergo a hydrocarbon insertion reaction with a ligand material (e.g., a second functional material and / or a first ligand material) attached to another quantum dot matrix, thus connecting one quantum dot matrix to another, thereby forming a cross-linked quantum dot material. As another example, when the first and / or second photosensitive groups contain azide groups, the azide groups attached to one quantum dot matrix can undergo a hydrocarbon insertion reaction with the first portion of the cross-linked material; the azide groups attached to the other quantum dot matrix can undergo a hydrocarbon insertion reaction with the second portion of the cross-linked material, thus connecting one quantum dot matrix to another through the cross-linked material, thereby forming a cross-linked quantum dot material.

[0161] It should be noted that when the quantum dot material includes a first ligand material and a second functional material, and the second functional material contains a second photosensitive group, the first photosensitive group and the second photosensitive group may be the same or different.

[0162] Understandably, based on the above principles, alkenyl groups, alkynyl groups, benzophenone groups, and azide groups all have photosensitive properties, which can cause quantum dot materials to undergo self-crosslinking reactions, or cause quantum dot materials to undergo crosslinking reactions under the action of crosslinking materials. In this way, quantum dot materials can form crosslinked quantum dot materials, thereby realizing the patterning of the target area of ​​the light-emitting layer.

[0163] In some embodiments, when the quantum dot material includes a first ligand material, the ratio between the mass of the first ligand material and the mass of the quantum dot bulk is greater than 0 and less than or equal to 0.45.

[0164] For example, the mass of the first ligand material can be measured by methods such as nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR) to obtain the ratio between the mass of the first ligand material and the mass of the quantum dot bulk.

[0165] For example, the ratio between the mass of the first ligand material and the mass of the quantum dot bulk is, for example, 0.05, 0.18, 0.27, 0.36, or 0.45.

[0166] In some embodiments, when the quantum dot material includes a first ligand material and a second functional material, the ratio between the sum of the masses of the first ligand material and the second functional material and the mass of the quantum dot bulk is greater than 0 and less than or equal to 0.45.

[0167] For example, the mass of the first ligand material and the second functional material can be measured by methods such as nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR) to obtain the ratio between the sum of the masses of the first ligand material and the second functional material and the mass of the quantum dot bulk.

[0168] For example, the ratio between the sum of the masses of the first ligand material and the second functional material and the mass of the quantum dot bulk is, for example, 0.09, 0.20, 0.27, 0.36, or 0.45.

[0169] Understandably, when the ratio of the mass of the ligand material to the mass of the quantum dot bulk is large (e.g., greater than 0.45), it leads to an excessive amount of ligand material bonded to the quantum dot bulk, resulting in a thick coating layer on the surface of the quantum dot bulk. This hinders the luminescence performance of the quantum dot bulk and also affects the film-forming properties of the luminescent layer, resulting in lower film density. Therefore, by adopting the above-mentioned configuration, the ratio of the total mass of the ligand material (including the first ligand material and / or the second functional material) to the mass of the quantum dot bulk can be kept within a suitable range. This allows for high luminescence performance of the quantum dots and good film-forming properties of the luminescent layer, while also ensuring good dispersibility of the quantum dot material and reducing the aggregation of the quantum dot bulk to prevent quantum dot bulk residues on the surface of the front film layer.

[0170] In some implementations, when QLED light-emitting devices are fabricated using direct photolithography, strong exposure conditions are used, which may damage the material of the light-emitting layer (e.g., quantum dot material).

[0171] In some embodiments, as shown in Figures 5 and 6, the functional material includes a third functional material. The third functional material comprises a third aromatic amine group, at least two initiating groups, and a solubilizing group. When the quantum dot material includes a first ligand material, the initiating group is configured to react with a first photosensitive group under light irradiation, causing the quantum dot material to form a cross-linked quantum dot material. When the quantum dot material includes a second functional material, and the second functional material includes a second photosensitive group, the initiating group is configured to react with the second photosensitive group under light irradiation, causing the quantum dot material to form a cross-linked quantum dot material. The solubility of the cross-linked quantum dot material in a predetermined solvent is less than the solubility of the quantum dot material in the predetermined solvent.

[0172] It should be understood that when the initiating group is configured to react with the first photosensitive group and / or the second photosensitive group under light to form a cross-linked quantum dot material, the third functional material can be reused as the cross-linked material described in the foregoing section. Here, the cross-linked material can also be understood as an initiator.

[0173] In some examples, the ligand material of the quantum dot material is the first ligand material. In this case, the initiating group of the third functional material can react with the first photosensitive group under light irradiation, so that the quantum dot material forms a cross-linked quantum dot material.

[0174] In some other examples, the ligand material of the quantum dot material is a second functional material containing a second photosensitive group. In this case, the initiating group of the third functional material can react with the second photosensitive group under light irradiation, causing the quantum dot material to form a cross-linked quantum dot material.

[0175] In some other examples, the ligand material of the quantum dot material is a first ligand material and a second functional material containing a second photosensitive group. In this case, the initiating group of the third functional material can react with the first photosensitive group and / or the second photosensitive group under light irradiation, so that the quantum dot material forms a cross-linked quantum dot material.

[0176] Understandably, firstly, the solubilizing group can increase the solubility of the third functional material in a preset solvent, enabling the third functional material to form a uniform and stable system with the quantum dot matrix. Secondly, when the third functional material is reused as a cross-linking material, the initiating group can react with the first and / or second photosensitive groups under light irradiation, causing the quantum dot material to form a cross-linked quantum dot material. This cross-linked quantum dot material has a denser cross-linked network structure, which is beneficial for improving the film retention effect after the development process. Thirdly, when the third functional material is reused as a cross-linking material, the exposure dose in the photolithography process can be reduced to some extent, weakening the impact of strong exposure conditions on the emissive layer material and preventing damage to the emissive layer material from strong exposure conditions.

[0177] It should be understood that when a quantum dot material includes a third functional material, the quantum dot material may include a first functional material and / or a second functional material, or may include a first functional material and / or a second functional material; there is no limitation here.

[0178] It should be noted that when the quantum dot material includes a first functional material and a third functional material, the first aromatic amine group and the third aromatic amine group may be the same or different. When the quantum dot material includes a second functional material and a third functional material, the second aromatic amine group and the third aromatic amine group may be the same or different; no restrictions are set here.

[0179] In some embodiments, the initiating group includes a thiol group.

[0180] For example, the thiol groups contained in the third functional material can be qualitatively or quantitatively measured by methods such as nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR).

[0181] It should be noted that when a functional material contains two thiol groups, it can be either a second or third functional material. In this case, the type of functional material can be determined based on its role in the quantum dot material. For example, if a functional material contains two thiol groups and can undergo cross-linking reactions with the first ligand material and / or the second functional material, it can be a third functional material. Conversely, if a functional material contains two thiol groups and cannot undergo cross-linking reactions with the first ligand material and / or other second functional materials, it can be a second functional material.

[0182] Understandably, when the initiating group includes a thiol group, the thiol group can undergo a cross-linking reaction with the first photosensitive group and / or the second photosensitive group under light irradiation. For example, when the first photosensitive group and / or the second photosensitive group are alkenyl groups, the thiol group can undergo a cross-linking reaction with the unsaturated bonds on the alkenyl group under light irradiation. In this way, multiple quantum dot bodies can be bridged to form a cross-linked quantum dot material with a dense cross-linked network structure, which is beneficial to improving the film retention effect after the development process and reducing the impact of strong exposure conditions on the material of the light-emitting layer.

[0183] In some embodiments, the ratio between the mass of the third functional material and the mass of the quantum dot bulk is in the range of 0 to 0.05.

[0184] For example, the ratio between the mass of the third functional material and the mass of the quantum dot bulk may be 0, 0.01, 0.02, 0.03, 0.045, or 0.05, etc. It should be understood that the ratio between the mass of the third functional material and the mass of the quantum dot bulk can be 0, that is, the quantum dot material may not include the third functional material.

[0185] Understandably, by setting the ratio between the mass of the third functional material and the mass of the quantum dot body to be in the range of 0 to 0.05, the mass of the third functional material can be kept within a suitable range, so that the cross-linked quantum dot material formed after cross-linking has a relatively dense cross-linked network structure, thereby improving the film retention effect after the development process and reducing the impact of strong exposure conditions on the material of the light-emitting layer.

[0186] In some embodiments, the functional material is selected from any of the structures shown in the following general formula (I).

[0187] R1 and R2 may be the same or different, and are independently selected from any one of the following: substituted or unsubstituted C1-C10 alkylene groups, substituted or unsubstituted C1-C10 alkoxy groups, substituted or unsubstituted C3-C10 cycloalkylene groups, substituted or unsubstituted C1-C10 heteroalkylene groups, substituted or unsubstituted C6-C12 arylene groups, substituted or unsubstituted C1-C12 heteroarylene groups, and groups containing solubilizing groups.

[0188] R3 to R8 may be the same or different, and are independently selected from hydrogen, deuterium, substituted or unsubstituted C1 to C10 alkyl, substituted or unsubstituted C1 to C10 alkoxy, substituted or unsubstituted C3 to C10 cycloalkyl, substituted or unsubstituted C1 to C10 heterocycloalkyl, substituted or unsubstituted C6 to C12 aryl and substituted or unsubstituted C1 to C12 heteroaryl, and groups containing a solubilizing group.

[0189] Any two of n1, n2, m1, and m2 are the same or different, and are independently selected from 0, 1, and 2 respectively. The sum of n1 and m1 is 2, the sum of n2 and m2 is 2, and at least one of n1 and n2 is not 0.

[0190] When the functional material is a first functional material, at least one of X and R1 to R8 contains the solubilizing group. When the functional material is a second functional material, X is a second coordinating group, and at least one of R1 to R8 contains a solubilizing group. When the functional material is a third functional material, the sum of n1 and n2 is greater than or equal to 2, X is an initiating group, and at least one of R1 to R8 contains a solubilizing group.

[0191] In the above general formula (I), an alkylene group of Cx refers to an alkylene group containing a total of x carbon (C) atoms, where x is a positive integer, and the same applies below. For the understanding of other alkylene groups of Cx, such as alkoxide groups, cycloalkylene groups, heteroalkylene groups, etc., please refer to the above content, and they will not be repeated here.

[0192] When R1 and R2 are selected from any one of substituted C1-C10 alkylene, substituted C1-C10 alkoxy, substituted C3-C10 cycloalkylene, substituted C1-C10 heterocyclic alkylene, substituted C6-C12 aryl or substituted C1-C12 heteroaryl, and / or R3-R8 are selected from any one of substituted C1-C10 alkyl, substituted C1-C10 alkoxy, substituted C3-C10 cycloalkyl, substituted C1-C10 heterocyclic alkyl, substituted C6-C12 aryl and substituted C1-C12 heteroaryl, there are no restrictions on the type and number of substituents.

[0193] Understandably, when the functional material is selected from any of the structures shown in general formula (I), and the functional material is a derivative of the aromatic amine derivative N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), it can be similar to TPD, possessing excellent hole transport performance. It can balance electron and hole mobility, effectively regulating the energy level structure of the hole transport layer and the quantum dot emitting layer, thus achieving a balance between holes and electrons injected into the emitting layer. Therefore, by selecting any of the structures shown in general formula (I) for the functional material, the hole transport performance of the quantum dot material can be improved, resulting in a more balanced hole and electron mobility in the emitting layer of the QLED light-emitting device.

[0194] For example, when n1 is 1, m1 is 1, m2 is 2, R1 is methylene, and X is an ester group, the functional material is the first functional material, and its structural formula can be as shown in formula (a).

[0195] For example, when n1 is 1, n2 is 1, m1 is 1, m2 is 1, R1 and R2 are methylene groups, and X is an ester group, the functional material is the first functional material, and its structural formula can be as shown in formula (a1) and formula (s).

[0196] For example, when n1 is 1, n2 is 1, m1 is 1, m2 is 1, R1 and R2 are methylene groups, and one of the two X groups is a carboxyl group and the other is an ester group, the functional material is a second functional material, and its structural formula can be as shown in formula (b1).

[0197] For example, when n1 is 1, m1 is 1, m2 is 2, and R1 is R y And R y It contains an ester group, X is a thiol group, and the functional material is a second functional material. Its structural formula can be shown as shown in formula (c).

[0198] For example, when n1 is 1, n2 is 1, m1 is 1, m2 is 1, and R1 and R2 are R y And R y When it contains an ester group and X is a thiol group, the functional material is a third functional material, and its structural formula can be as shown in formula (c1).

[0199] It should be noted that the structural formulas listed above are examples of the structures of functional materials, not restrictions on functional materials. Moreover, (a) and others in the above structural formulas are alternative names for each structural formula, not part of the structural formula itself, where x takes a positive integer.

[0200] The following examples illustrate the synthesis process of a functional material with the structure shown in general formula (I). Examples include a first functional material with the structure shown in formula (a) and a second functional material with the structure shown in formula (c). It should be understood that the synthesis processes of other first functional materials (excluding the first functional material with the structure shown in formula (a)) and other second functional materials (excluding the second functional material with the structure shown in formula (c)) can be obtained by controlling reaction conditions (e.g., reactants, solvent, feed ratio, reaction temperature, etc.), and will not be exhaustively described here.

[0201] In some examples, firstly, intermediate M1 is synthesized using TPD and N-bromosuccinimide; the structural formulas of TPD, N-bromosuccinimide, and intermediate M1, as well as the chemical reaction formula for the synthesis of intermediate M1, are shown below.

[0202] For example, the reaction of synthesizing intermediate M1 using TPD and N-bromosuccinimide is a Wol-Ziegler bromination reaction. The specific process includes: dissolving TPD and N-bromosuccinimide in chloroform at a molar ratio of 1:2, heating to 50°C to 70°C, reacting at this temperature for 6 to 24 hours, and then purifying and filtering to obtain intermediate product M1.

[0203] It should be noted that the bromination reaction site in the above reaction is not limited to the methyl group. In practical applications, other bromine-substituted products besides intermediate M1 can be obtained by changing the reactants and reaction conditions. For example, by adding an appropriate amount of glacial acetic acid, a bromination reaction on the benzene ring can be induced to obtain a tetrabromine-substituted product as shown in the following formula. In this case, by appropriately adjusting the conditions described below for synthesizing intermediate M2 using intermediate M1, synthesizing the first functional material using intermediate M2, synthesizing the second functional material using the first functional material, and synthesizing the second functional material using intermediate M2, the first and second functional materials based on the tetrabromine-substituted product can be obtained. For example, the first functional material with the structure shown in (s) can be obtained.

[0204] Then, intermediate M2 is synthesized using intermediate M1 and pyridine. The structural formulas of intermediate M1, pyridine, and intermediate M2, as well as the chemical reaction formula for the synthesis of intermediate M2, are shown below.

[0205] For example, the reaction of synthesizing intermediate M2 using intermediate M1 and pyridine is an aromatic amination reaction. The specific process includes: dissolving intermediate M1 in DMSO, adding pyridine in a 1 molar ratio, heating to 60°C, and reacting at this temperature for 6 to 24 hours, followed by purification and filtration to obtain intermediate product M2. In this process, pyridine can replace an equimolar amount of bromine.

[0206] Then, a first functional material with the structure shown in formula (a) is synthesized using intermediate M2 and ethyl mercaptoester. The structural formulas of intermediate M2, ethyl mercaptoester, and the first functional material, as well as the chemical reaction formula for synthesizing the first functional material with the structure shown in formula (a) are shown below.

[0207] For example, the reaction of synthesizing the first functional material with the structure shown in formula (a) using intermediate M2 and ethyl mercaptoside is a nucleophilic substitution reaction. The specific process includes: dissolving an appropriate amount of NaH or K2CO3 in DMF to obtain a mixture, then dissolving intermediate M2 in the mixture, adding ethyl mercaptoside at a molar ratio of 1.5, heating to 60°C, and reacting at this temperature for 6 to 24 hours to obtain the first functional material with the structure shown in formula (a).

[0208] It should be noted that in the above reaction, ethyl mercaptoacetate can be replaced with other long-chain compounds with similar structures.

[0209] In some examples, intermediate M2 is used in conjunction with dithiol molecules (SH-R) y -SH, R y Containing ester groups, it can react to obtain a second functional material with the structure shown in formula (c). The structural formulas of intermediate M2, dithiol molecules and the second functional material, as well as the chemical reaction formula for the synthesis of the second functional material with the structure shown in formula (c) are shown below.

[0210] The above is an exemplary description of a method for preparing a functional material with a structure as shown in general formula (II). Another general formula structure of functional materials will be exemplarily introduced below.

[0211] In some embodiments, the functional material is selected from any of the structures shown in the following general formula (II).

[0212] R9 is selected from any one of the following: substituted or unsubstituted C1-C10 alkylene groups, substituted or unsubstituted C1-C10 alkoxy groups, substituted or unsubstituted C3-C10 cycloalkylene groups, substituted or unsubstituted C1-C10 heteroalkylene groups, substituted or unsubstituted C6-C12 arylene groups, substituted or unsubstituted C1-C12 heteroarylene groups, and groups containing a solubilizing group.

[0213] p is selected from 0, 1, and 2.

[0214] q is selected from any one of 1, 2 and 3, and the sum of p and q is 3.

[0215] When the functional material is a first functional material, at least one of X and R9 contains a solubilizing group. When the functional material is a second functional material, X is a second coordinating group, and R9 contains a solubilizing group. When the functional material is a third functional material, q is greater than or equal to 2, X is an initiating group, and at least one of the R9 connected to X contains a solubilizing group.

[0216] For an understanding of Cx, please refer to the previous text; it will not be repeated here.

[0217] When R9 is selected from any of the following: substituted C1-C10 alkylene, substituted C1-C10 alkoxy, substituted C3-C10 cycloalkylene, substituted C1-C10 heteroalkylene, substituted C6-C12 aryl, and substituted C1-C12 heteroaryl, there are no restrictions on the type and number of substituents.

[0218] Understandably, when the functional material is selected from any of the structures shown in general formula (II), the functional material is a derivative of the carbazole derivative 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA), which, similar to TCTA, exhibits excellent hole transport performance. Specifically, the structure shown in general formula (II) contains three carbazole units bonded to nitrogen atoms. These carbazole units are electron-rich, possess a stable conjugated system, and have a high electron cloud density, resulting in strong hole transport performance. Therefore, by selecting any of the structures shown in general formula (II) for the functional material, the hole transport performance of quantum dot materials can be improved, leading to a more balanced hole mobility and electron mobility in the emitting layer of QLED light-emitting devices.

[0219] For example, when q is 1 or 2, R9 is methylene, and X is an ester group, the functional material is the first functional material, and its structural formula can be as shown below.

[0220] For example, when q is 1 and X is a thiol group, the functional material is a second functional material, and its structural formula can be as shown below.

[0221] For example, p is 1, q is 2, R9 is methylene, and when X is a thiol group, the functional material is a third functional material, and its structural formula can be as shown in formula (k).

[0222] It should be noted that the structural formulas listed above are examples of the structures of functional materials, not restrictions on functional materials. Furthermore, (k) and other terms in the above structural formulas are approximations of each structural formula, not part of the structural formula itself, where x takes a positive integer value.

[0223] The following examples illustrate the synthesis process of a functional material with the structure shown in general formula (II), using a first functional material with the structure shown in formula (d) and a second functional material with the structure shown in formula (f) as examples. It should be understood that the synthesis processes of other first functional materials besides the first functional material with the structure shown in formula (d) and other second functional materials besides the second functional material with the structure shown in formula (f) can be obtained by controlling reaction conditions (e.g., reactants, solvent, feed ratio, reaction temperature, etc.), and will not be exhaustively described here.

[0224] In some examples, intermediate M3 is first synthesized using TCTA and p-fluorobenzoyl chloride; the structural formulas of TCTA, p-fluorobenzoyl chloride, and intermediate M3, and the chemical reaction formula for the synthesis of intermediate M3 are shown below.

[0225] For example, the reaction of synthesizing intermediate M3 using TCTA and p-fluorobenzoyl chloride is a Friedel-Crafts acylation reaction. The specific process includes: dissolving a strong Lewis acid (e.g., anhydrous AlCl3 or FeCl3), TCTA and p-fluorobenzoyl chloride in dichloromethane under ice bath conditions, then slowly raising the temperature to room temperature and reacting at room temperature for 3 to 12 hours, followed by cooling in an ice bath, purification and filtration to obtain intermediate M3.

[0226] It should be noted that the number of reaction sites in the above reaction is not limited to one. For example, the number of reaction sites in the Friedel-Crafts acylation reaction can be two to obtain intermediate M5 as shown in the following formula. In this case, by appropriately adjusting the conditions for synthesizing the first functional material using the intermediate, synthesizing the second functional material using the first functional material, and synthesizing the second functional material using the intermediate as described below, the first functional material and the second functional material based on intermediate M5 can be obtained. For example, the first functional material with the structure shown in (g) and the third functional material with the structure shown in (k) can be obtained.

[0227] It should be noted that the reaction for synthesizing intermediates using TCTA is not limited to Friedel-Crafts acylation; other reactions are also possible. For example, the reaction for synthesizing intermediates using TCTA can be the Wol-Ziegler bromination reaction, in which case the reaction formula for synthesizing intermediate M4 can be shown below.

[0228] Then, a first functional material with the structure shown in formula (d) is synthesized using intermediate M3 and ethyl mercaptohydrate. The structural formulas of intermediate M3, ethyl mercaptohydrate, and the first functional material, as well as the chemical reaction formula of the first functional material with the structure shown in formula (d), are shown below.

[0229] For example, the reaction of synthesizing the first functional material with the structure shown in formula (d) using intermediate M3 and ethyl mercaptoester is a nucleophilic substitution reaction. The specific process includes: mixing an appropriate amount of NaH or K2CO3 with DMF to obtain a mixture, then adding intermediate M3 to the mixture and adding ethyl mercaptoester at a molar ratio of 1.5, heating to 60°C, and reacting at 60°C for 6 h to 24 h to obtain the first functional material with the structure shown in formula (d).

[0230] It should be noted that in the above reaction, ethyl mercaptoacetate can be replaced with other long-chain compounds with similar structures.

[0231] In some examples, intermediate M3, in reaction with dithiol molecules (SH-Ry-SH, where Ry contains an ester group), can yield a second functional material with the structure shown in formula (f). The structural formulas of intermediate M3, the dithiol molecule, and the second functional material, as well as the chemical reaction formula for the synthesis of the second functional material with the structure shown in formula (f), are shown below.

[0232] The above is an exemplary description of quantum dot materials. The structure of the light-emitting device 100 will be described exemplary below.

[0233] In some examples, as shown in Figures 1 and 7, the light-emitting device 100 can be classified into top-emitting, bottom-emitting, and double-sided emitting light-emitting devices according to the direction of light emission.

[0234] In the bottom-emitting light-emitting device, the light emitted by the light-emitting layer 13 is emitted from the substrate 210 side. At this time, the anode 15 and the cathode 11, which are relatively closer to the substrate 210, can be a light-transmitting electrode (such as a transparent electrode or a semi-transparent electrode), and the one that is relatively farther away from the substrate 210 can be an opaque electrode; for example, an opaque reflective electrode.

[0235] In a top-emitting light-emitting device, the light emitted by the light-emitting layer 13 is emitted from the side away from the substrate 210. Since the light needs to be emitted from the side away from the substrate 210, the one of the anode 15 and the cathode 11 that is relatively closer to the substrate 210 can be an opaque electrode, such as an opaque reflective electrode, while the one that is relatively farther away from the substrate 210 can be a transparent electrode or a semi-transparent electrode.

[0236] Understandably, in a bottom-emitting light-emitting device, light passes through the substrate 210, causing it to be blocked by the pixel driving circuit 231 on the substrate 210. Therefore, compared to a bottom-emitting light-emitting device, a top-emitting light-emitting device has a relatively higher aperture ratio in the pixel defining layer 221 and a relatively higher light transmittance.

[0237] The double-sided emitting light-emitting device 100 allows light emitted from its light-emitting layer to exit from both the side away from the substrate 210 and the side of the substrate 210, enabling the display panel to have a double-sided display function. Since the light needs to be emitted in two directions, both the anode 15 and the cathode 11 must be configured as light-transmitting electrodes.

[0238] In some examples, the light-emitting device 100 can be classified as a positive light-emitting device and an inverted light-emitting device, depending on the type of electrode that contacts the substrate (e.g., including substrate 210 and driving circuit layer 230).

[0239] As shown in Figure 2A, when the electrode in contact with the substrate is the anode 15, the light-emitting device 100 is a positive light-emitting device. The anode 15 in contact with the substrate can realize the function of hole generation and injection. The structure of the positive light-emitting device includes, for example, an anode 15, a hole transport unit 14, a light-emitting layer 13, an electron transport unit 12, and a cathode 15 arranged sequentially in a direction away from the substrate 210.

[0240] As shown in Figure 2B, when the electrode in contact with the substrate is the cathode 11, the light-emitting device 100 is an inverted light-emitting device. The cathode 11 in contact with the substrate can realize the function of generating and injecting electrons. The structure of the inverted light-emitting device includes, for example, a cathode 11, an electron transport unit 12, a light-emitting layer 13, a hole transport unit 14, and an anode 15 arranged sequentially in a direction away from the substrate 210.

[0241] The hole transport unit 14 includes, for example, a hole injection layer and a hole transport layer. The electron transport unit 12 includes, for example, an electron transport layer and an electron injection layer. For exemplary descriptions of the cathode 11, electron injection layer, electron transport layer, light-emitting layer, hole transport layer, hole injection layer, and anode 15, please refer to the foregoing sections, and they will not be repeated here.

[0242] It should be noted that Figures 2A and 2B are schematic diagrams of the display panel 200 after omitting the driving circuit layer 230.

[0243] In some embodiments, as shown in FIG2B, the light-emitting device 100 is disposed on the substrate 210. The cathode 11 is closer to the substrate 210 than the anode 15.

[0244] Understandably, by setting it up this way, the light-emitting device 100 is an inverted light-emitting device. On the one hand, the material of the thin-film transistor substrate 210 is mainly n-type semiconductor material, and the structure of the inverted light-emitting device can effectively match this characteristic, which can simplify the process and improve the display resolution. On the other hand, when preparing the inverted light-emitting device, other film layers after the light-emitting layer 13 (e.g., hole transport layer and hole injection layer) can be prepared by vapor deposition, which can achieve uniform film layer control and improve the film layer uniformity of the light-emitting device 100.

[0245] In some examples, the light-emitting device 100 is an inverted top-emitting light-emitting device, which can be applied to QLED display panels. This facilitates the large-scale application of QLED display technology.

[0246] On another aspect, some embodiments of this disclosure provide a method for fabricating a light-emitting device 100, as shown in Figures 7 and 8, including S1.

[0247] S1: Forming a cathode 11, an anode 15, and a light-emitting layer 13. The cathode 11 and anode 15 are positioned opposite each other. The light-emitting layer 13 is located between the anode 11 and the cathode 15. The material of the light-emitting layer 13 includes cross-linked quantum dot material formed from quantum dot material. The quantum dot material includes a quantum dot matrix and a functional material. The functional material contains aromatic amine groups and solubilizing groups. The solubilizing groups are used to increase the solubility of the functional material in a preset solvent. The ratio between the mass of the functional material and the mass of the quantum dot matrix is ​​greater than 0 and less than or equal to 0.45.

[0248] The beneficial effects achievable by the above-mentioned method for preparing light-emitting devices are the same as those achievable by the above-mentioned quantum dot materials, and will not be repeated here.

[0249] In some embodiments, a cathode 11, an anode 15, and a light-emitting layer 13 are formed, including S1.1 to S1.3.

[0250] S1.1: Forming cathode 11.

[0251] For an understanding of the cathode 11, please refer to the foregoing exemplary description of the cathode 11, which will not be repeated here.

[0252] S1.2: Forming the light-emitting layer 13.

[0253] For an understanding of the light-emitting layer 13, please refer to the foregoing exemplary description of the light-emitting layer 13, which will not be repeated here.

[0254] S1.3: Forms anode 15.

[0255] For an understanding of anode 15, please refer to the foregoing exemplary description of anode 15, which will not be repeated here.

[0256] Understandably, when the formation of cathode 11, anode 15 and light-emitting layer 13 includes S1.1 to S1.3, the light-emitting device is an inverted light-emitting device. As mentioned above, this can simplify the process flow and improve the display resolution; moreover, it can achieve uniform film layer control, thereby improving the film layer uniformity of the light-emitting device 100.

[0257] In some examples, S1.1A is included after S1.1 and before S1.2.

[0258] S1.1A: Form an electron transport unit 12, which includes, for example, at least one of an electron injection layer (EIL), an electron transport layer (ETL), and a hole blocking layer (EBL).

[0259] For an understanding of the electronic transmission unit 12, please refer to the foregoing exemplary description of the electronic transmission unit 12, which will not be repeated here.

[0260] For example, the electron transport unit 12 includes an electron transport layer, and the electron transport layer is prepared by the sol-gel method. Of course, other methods can also be used to prepare the electron transport layer.

[0261] For example, the electron transport unit 12 includes an electron transport layer, and the material of the electron transport layer is zinc oxide / magnesium zinc oxide. In this case, the preparation method of the electron transport layer may include an annealing process. By setting it this way, firstly, the electrical properties of the electron transport layer itself can be improved, and secondly, the damage to the light-emitting layer 13 and other functional films caused by heat treatment can be effectively reduced.

[0262] In some examples, S1.3A is included after S1.2 and before S1.3.

[0263] S1.3A: Forming a hole transport unit 14, which includes, for example, at least one of a hole injection layer (HIL), a hole transport layer (HTL), and an electron blocking layer (EBL).

[0264] For an understanding of the hole transmission unit 14, please refer to the foregoing exemplary description of the hole transmission unit 14, which will not be repeated here.

[0265] In some embodiments, the light-emitting device 100 is formed on the substrate 210, as shown in FIG9, and the formation of the light-emitting layer 13 includes S1.2.1 to S1.2.3.

[0266] S1.2.1: The material of the initial light-emitting layer 13a is spin-coated on the side of the cathode 11 away from the substrate 210 (see Figure 1) to form the initial light-emitting layer 13a. The material of the initial light-emitting layer 13a includes quantum dot material and a preset solvent.

[0267] For example, the material of the initial light-emitting layer 13a is spin-coated on the side of the electron transport unit 12 (e.g., electron transport layer) away from the cathode 11 to form the initial light-emitting layer 13a.

[0268] S1.2.2: Expose the target area of ​​the initial luminescent layer 13a, so that the exposed part of the material in the initial luminescent layer 13a is transformed into cross-linked quantum dot material.

[0269] For example, exposing the target area of ​​the initial luminescent layer 13a may include: exposing it with light of a first wavelength or full-spectrum light. Alternatively, exposing it with light of a second wavelength followed by exposing it with light of the first wavelength. Or, exposing it with light of the first wavelength followed by exposing it with light of the second wavelength. Here, the first wavelength is, for example, ultraviolet light with a wavelength of 365 nm, and the second wavelength is, for example, ultraviolet light with a wavelength of 405 nm.

[0270] For example, in S1.2.2, a mask template or mask layer is used to expose the target area of ​​the initial light-emitting layer 13a.

[0271] S1.2.3: The initial luminescent layer 13a is developed using a developer solution. The developer solution includes a pre-set solvent.

[0272] It should be understood that after development, the quantum dot material in the unexposed area is removed, while the cross-linked quantum dot material in the exposed area is retained, thereby achieving the patterning of the light-emitting layer 13.

[0273] Understandably, when the formation of the light-emitting layer 13 includes S1.2.1 to S1.2.3, the process for preparing the light-emitting layer 13 is a direct photolithography process. Compared with the indirect photolithography process, the light-emitting device preparation process can have less destructive effect on the film quality and can simplify the patterning process.

[0274] In some embodiments, as shown in FIG9, the material forming the initial light-emitting layer 13a includes: mixing the quantum dot bulk, the initial ligand material, and a preset solvent to form a quantum dot stock solution. The ratio between the mass of the initial ligand material and the mass of the quantum dot bulk is greater than 0 and less than or equal to 0.13.

[0275] In some examples, the initial ligand material includes a first ligand material. The first ligand material can be ligated to the quantum dot bulk. The first ligand material contains a first photosensitive group.

[0276] In other examples, the initial ligand material includes a second functional material. The second functional material can be ligated into the quantum dot bulk. The second functional material contains a second photosensitive group. In this case, the functional material includes the second functional material.

[0277] In other examples, the initial ligand material comprises a first ligand material and a second functional material. The first ligand material and the second functional material are collimated within the quantum dot bulk. The first ligand material contains a first photosensitive group. In this case, the functional material comprises a second functional material.

[0278] For example, the ratio between the mass of the initial ligand material and the mass of the quantum dot bulk can be 0.01, 0.03, 0.05, 0.07, 0.08, 0.10, or 0.13, etc.

[0279] Understandably, when the ratio between the mass of the initial ligand material and the mass of the quantum dot bulk is greater than 0 and less than or equal to 0.13, it can improve the dispersion of the quantum dot bulk in the quantum dot stock solution and facilitate the long-term storage of the quantum dot stock solution.

[0280] In some examples, quantum dot stock solutions with MMES as the initial ligand material were prepared using a ligand exchange process. Before the ligand exchange, the ligand material ligated to the quantum dot matrix was oleic acid; after the exchange, MMES ligands were ligated to the quantum dot matrix. These quantum dot stock solutions were then subjected to thermogravimetric analysis (TGA), and the measurement results are shown in Figure 10. The weight loss ratios for samples A, B, and C were 11.04%, 10.46%, and 10.03%, respectively. As shown in Figure 10, the ratio of the initial ligand material mass to the sum of the quantum dot matrix mass and the initial ligand material mass in the quantum dot stock solution can be stably controlled at approximately 10.5%, indicating high reproducibility of the ligand exchange process.

[0281] In some embodiments, as shown in FIG9, the material forming the initial luminescent layer 13a further includes a first supplementary ligand material added to the quantum dot stock solution. The ratio between the mass of the first supplementary ligand material and the mass of the quantum dot bulk is in the range of 0 to 0.35. If the initial ligand material includes the first ligand material, the first supplementary ligand material includes the first ligand material. If the initial ligand material includes a second functional material, the first supplementary ligand material includes the second functional material.

[0282] For example, the ratio between the mass of the first supplementary ligand material and the mass of the quantum dot bulk can be 0, 0.02, 0.05, 0.08, 0.10, 0.15, 0.20, 0.25, or 0.35, etc. It should be understood that the ratio between the mass of the first supplementary ligand material and the mass of the quantum dot bulk can be 0, that is, the quantum dot stock solution may not contain the first supplementary ligand material.

[0283] Understandably, when quantum dots aggregate, they are more likely to remain on the surface of the pre-film layer. Adding a first supplementary ligand to the quantum dot stock solution serves several purposes: first, it acts as a dispersant, reducing quantum dot aggregation; second, it allows the supplementary ligand to directly coordinate with the quantum dot mass, passivating surface defects and further reducing aggregation; and third, it enables a dynamic ligand exchange reaction between the supplementary ligand and the initial ligand, displacing the quantum dots originally adsorbed on the pre-film layer back into the developing solution and removing them during subsequent development processes. This prevents quantum dot material from remaining on the surface of the pre-film layer after development.

[0284] Furthermore, when the ratio of the mass of the first supplementary ligand material to the mass of the quantum dot matrix is ​​greater than 0.35, it may result in a larger amount of ligand material ligated to the quantum dot matrix, hindering the luminescence performance of the quantum dot matrix and increasing the isolation between the quantum dot and its surrounding environment, thus affecting the film-forming performance of the luminescent layer 13. Therefore, by setting the ratio of the mass of the first supplementary ligand material to the mass of the quantum dot matrix to be within the range of 0 to 0.35, the ratio can be kept within a suitable range. This ensures both the luminescence performance of the quantum dot matrix and the film-forming performance of the luminescent layer 13, while preventing quantum dot material residue on the surface of the pre-film layer after development.

[0285] Furthermore, when the first supplementary ligand material includes both the first ligand material and the second functional material, the electrical performance of the light-emitting device can be controlled by adjusting their ratio, thereby maintaining the electrical performance to a greater extent.

[0286] In some embodiments, as shown in FIG9, the material of the initial light-emitting layer 13a further includes a first functional material. The first functional material is not connected to the quantum dot body. In this case, the functional material includes the first functional material.

[0287] In some embodiments, as shown in FIG9, the developing solution further includes a first functional material. The first functional material is not connected to the quantum dot bulk. In this case, the functional material includes the first functional material.

[0288] For a description of the first functional material, please refer to the foregoing exemplary description of the first functional material, which will not be repeated here.

[0289] Understandably, when the material of the initial luminescent layer 13a and / or the developing solution includes the first functional material, the first functional material can act as a dispersant to reduce the aggregation of quantum dot materials. Moreover, the first functional material can play a physical barrier role between the quantum dot body and the front film layer (such as the electron transport layer) material, and between the ligand material and the lower functional layer material, weakening the anchoring effect of the front film layer material on the quantum dots. In this way, the residue of quantum dot materials on the surface of the front film layer can be prevented, thereby solving the problem of color crosstalk.

[0290] In some embodiments, the material of the initial light-emitting layer 13a further includes a third functional material. The functional material includes a third functional material. The third functional material contains at least two initiating groups. In this case, the functional material includes a third functional material. When the quantum dot material includes a first ligand material, the initiating group is configured to react with a first photosensitive group under illumination to form a cross-linked quantum dot material; when the quantum dot material includes a second functional material, and the second functional material contains a second photosensitive group, the initiating group is configured to react with the second photosensitive group under illumination to form a cross-linked quantum dot material.

[0291] For a description of the third functional material, please refer to the foregoing exemplary description of the third functional material, which will not be repeated here.

[0292] Understandably, through the above configuration, the third functional material can act as a crosslinking material, reacting with the first and / or second photosensitive groups under illumination to form crosslinked quantum dot materials. These crosslinked quantum dot materials possess a denser crosslinked network structure, which is beneficial for improving film retention after the development process. Furthermore, when the third functional material can act as a crosslinking material, it can reduce the exposure dose in the photolithography process to some extent, mitigating the impact of strong exposure conditions on the emissive layer material and preventing damage to the emissive layer material from strong exposure conditions.

[0293] In some embodiments, as shown in FIG9, the developing solution further includes a second supplementary ligand material. The ratio between the mass of the second supplementary ligand material in the developing solution and the mass of the quantum dot bulk in the material of the initial luminescent layer 13a ranges from 0 to 0.1. If the initial ligand material includes a first ligand material, the second supplementary ligand material includes the first ligand material. If the initial ligand material includes a second functional material, the second supplementary ligand material includes the second functional material.

[0294] For example, the ratio between the mass of the second supplementary ligand material in the developing solution and the mass of the quantum dot bulk in the material of the initial luminescent layer 13a can be 0, 0.01, 0.03, 0.05, 0.06, 0.08, or 0.1. It should be understood that the ratio between the mass of the second supplementary ligand material in the developing solution and the mass of the quantum dot bulk in the material of the initial luminescent layer 13a can be 0, meaning that the developing solution may not contain the second supplementary ligand material.

[0295] Understandably, with the above settings, the second supplementary ligand material in the developer is the same as the initial ligand material in the initial luminescent layer. This allows the second supplementary ligand material to undergo a ligand exchange reaction with the initial ligand material, displacing the quantum dot matrix located in the unexposed area and originally adsorbed on the front film layer back into the developer. This reduces the residue of quantum dot material on the surface of the front film layer, prevents color crosstalk, and improves the color gamut of the display panel. Furthermore, when the ratio of the mass of the second supplementary ligand material to the mass of the quantum dot matrix in the initial luminescent layer 13a is large (e.g., greater than 0.1), it may reduce the fluidity and solubility of the developer, resulting in poor development. Therefore, by setting the ratio of the mass of the second supplementary ligand material in the developer to the mass of the quantum dot matrix in the initial luminescent layer 13a to a range of 0 to 0.1, the residue of quantum dot material on the surface of the front film layer can be reduced while ensuring the development effect of the developer.

[0296] Moreover, when the second supplementary ligand material includes the first ligand material and the second functional material, the electrical performance of the light-emitting device can be regulated by adjusting the ratio of the two, thereby maintaining the electrical performance to a greater extent.

[0297] In order to objectively evaluate the technical effects of the embodiments of this disclosure, the technical solutions provided by this disclosure will be described in detail and by way of example through the following experimental examples and comparative examples.

[0298]

Example 1

[0299] The following embodiment fabricates a display panel 200, the structure of which is shown in Figure 11 for the light-emitting device 100. The fabrication method includes steps R1 to R9.

[0300] R1: Prepare the backplate; the backplate includes a substrate 210 and a patterned cathode layer disposed on the substrate 210, the patterned cathode layer includes a plurality of cathodes 11 (ITO electrodes); the backplate is cleaned sequentially with deionized water and isopropanol, and then dried with a nitrogen gun and baked for later use.

[0301] R2: Preparation of electron transport layer 121, specifically including: adding 1g of zinc acetate dihydrate to a mixed solution of 5mL ethanolamine and dimethoxyethanol, and heating and stirring at 60℃~80℃ for 30min~60min to obtain a zinc oxide precursor solution; after the zinc oxide precursor solution is allowed to stand and cool, an appropriate amount of the zinc oxide precursor solution is dropped onto a backing plate and spin-coated into a film, and then placed on a hot stage at 150℃~300℃ for heat treatment to form a nano zinc oxide film, which is the electron transport layer 121.

[0302] R3: Fabrication of the luminescent layer 13 of the red light-emitting device specifically includes: First, spin-coating the material of the first initial luminescent layer onto the electron transport layer 121. The material of the first initial luminescent layer includes: a red quantum dot matrix, a first ligand material MMES, and a functional material, wherein the functional material exists in a free form or in a form liganded to the quantum dot matrix. Then, using a mask, the target area of ​​the first initial luminescent layer (which can be understood as the area corresponding to the red sub-pixel) is exposed. Subsequently, the first initial luminescent layer is developed using a developing solution to remove the material of the first initial luminescent layer located in the non-target area, while retaining the cross-linked quantum dot material located in the target area, thus obtaining the luminescent layer 13 of the red light-emitting device; the developing solution includes PGMEA, the first ligand material MMES, and the functional material.

[0303] R4: Fabrication of the light-emitting layer 13 of the green light-emitting device specifically includes: First, spin-coating the material of the second initial light-emitting layer onto the electron transport layer 121. The material of the second initial light-emitting layer includes: a green quantum dot matrix, a first ligand material MMES, and a functional material, wherein the functional material exists in a free form or in a form liganded to the quantum dot matrix. Then, using a mask, the target area of ​​the second initial light-emitting layer (which can be understood as the area corresponding to the green sub-pixel) is exposed. Subsequently, the second initial light-emitting layer is developed using a developing solution to remove the material of the second initial light-emitting layer located in the non-target area, while retaining the cross-linked quantum dot material located in the target area, thus obtaining the light-emitting layer of the green light-emitting device; the developing solution includes PGMEA, the first ligand material MMES, and the functional material.

[0304] R5: Fabrication of the luminescent layer 13 of the blue light-emitting device specifically includes: First, spin-coating the material of the third initial luminescent layer onto the electron transport layer 121. The material of the third initial luminescent layer includes: a blue quantum dot matrix, a first ligand material MMES, and a functional material, wherein the functional material exists in a free form or in a form liganded to the quantum dot matrix. Then, using a mask, the target area of ​​the third initial luminescent layer (which can be understood as the area corresponding to the blue sub-pixel) is exposed. Subsequently, the third initial luminescent layer is developed using a developing solution to remove the material of the third initial luminescent layer located in the non-target area, while retaining the cross-linked quantum dot material located in the target area, thus obtaining the luminescent layer of the blue light-emitting device; the developing solution includes PGMEA, the first ligand material MMES, and the functional material.

[0305] R6: Fabrication of hole transport layer 141, specifically including: using spin coating or vapor deposition process to deposit the material (such as TFB) of hole transport layer 141 on the light-emitting layer 13 of red light-emitting device, the light-emitting layer 13 of green light-emitting device, and the light-emitting layer 13 of blue light-emitting device.

[0306] R7: The hole injection layer 142 is prepared by using a spin coating process or a vapor deposition process to deposit the material (such as PEDOT) of the hole injection layer 142 onto the light-emitting layer 13 of the red light-emitting device, the light-emitting layer 13 of the green light-emitting device, and the light-emitting layer 13 of the blue light-emitting device.

[0307] R8: Preparation of anode 15, specifically including: depositing Ag material of anode 15 onto hole injection layer 142 by vapor deposition.

[0308] R9: Package.

[0309]

Example 2

[0310] The following embodiment fabricates a display panel 200, the structure of which is shown in Figure 11 for the light-emitting device 100. The fabrication method includes M1 to M9.

[0311] M1: Prepare the backplate.

[0312] M2: Fabrication of electron transport layer 121.

[0313] M3: Light-emitting layer 13 for preparing red light-emitting devices.

[0314] M4: Light-emitting layer 13 for fabricating green light-emitting devices.

[0315] M5: Light-emitting layer 13 for fabricating blue light-emitting devices.

[0316] M6: Prepare hole transport layer 141.

[0317] M7: Prepare hole injection layer 142.

[0318] M8: Preparation of anode 15.

[0319] M9: Package.

[0320] For an understanding of the preparation methods of M1 to M9, please refer to the description of the preparation methods of R1 to R9 in the preceding section, which will not be repeated here.

[0321] In this embodiment, the materials used to form the first initial light-emitting layer 13 for the red light-emitting device, the second initial light-emitting layer 13 for the green light-emitting device, and the third initial light-emitting layer 13 for the blue light-emitting device all include: a quantum dot body, a first ligand material MMES, and functional materials, including a third functional material. The functional materials, excluding the third functional material, exist either in a free form or in a form coordinated to the quantum dot body.

[0322]

Example 3

[0323] In this embodiment, a first quantum dot solution, a second quantum dot solution, a third quantum dot solution, a fourth quantum dot solution, and a fifth quantum dot solution were spin-coated onto an electron transport layer containing zinc oxide / magnesium zinc oxide, respectively. The residual state of the quantum dot material after development was characterized to verify the effect of the ligand material content in the quantum dot solution on the residual state of the quantum dot material.

[0324] The residual condition was characterized using photoluminescence testing and scanning electron microscopy (SEM) observation. The photoluminescence effects of the first, second, third, fourth, and fifth quantum dot solutions are shown in Figures 12(a), 12(b), 12(c), 12(d), and 12(e), respectively. The SEM images of the fourth and fifth quantum dot solutions are shown in Figures 13(a) and 13(b), respectively.

[0325] The first, second, third, fourth, and fifth quantum dot solutions all include the red quantum dot bulk (RQD) and the first ligand material MMES, but the content of the first ligand material MMES varies in each quantum dot solution. Specifically, in the first quantum dot solution (i.e., the quantum dot stock solution), the mass ratio of the first ligand material MMES to the mass of the red quantum dot bulk (RQD) is 11.67%. The second, third, fourth, and fifth quantum dot solutions are obtained by adding the first ligand material MMES to the first quantum dot solution (i.e., the quantum dot stock solution), and the mass ratios of the first ligand material MMES to the mass of the red quantum dot bulk (RQD) in the second, third, fourth, and fifth quantum dot solutions are 20%, 26.25%, 32.5%, and 45%, respectively.

[0326] As shown in Figure 12(a), when the spin-coating solution is the first quantum dot solution, the quantum dot material on the surface of the electron transport layer is difficult to remove after development, resulting in severe photoluminescence of the quantum dot material under photoexcitation. As shown in Figure 12(b), when the spin-coating solution is the second quantum dot solution, the development effect is improved, the amount of quantum dot material remaining on the surface of the electron transport layer is reduced, and the photoluminescence intensity is weakened. As shown in Figure 12(e), when the spin-coating solution is the fifth quantum dot solution, the development effect is significantly improved, and the surface of the electron transport layer is nearly transparent.

[0327] According to statistics, the number of residual quantum dots after development in Figure 13(a) is approximately 62 per μm. 2 In Figure 13(b), the number of residual quantum dots after development is approximately 17 per μm. 2 .

[0328] In summary, by adding ligand materials (such as the first ligand material MMES) to the quantum dot stock solution, the development effect on the zinc oxide / magnesium oxide zinc electron transport layer can be effectively improved.

[0329]

Example 4

[0330] In this embodiment, the second quantum dot solution described in Example 3 was spin-coated onto an electron transport layer containing zinc oxide / zinc magnesium oxide, and then developed using a first developer, a second developer, and a third developer, respectively. The residual quantum dot material after development was characterized to verify the effect of the ligand material content in the developer on the residual quantum dot material. The residual condition was characterized by photoluminescence testing.

[0331] The first, second, and third developing solutions all contain PGMEA and the first ligand material MMES, but the content of the first ligand material MMES in each developing solution is different. Specifically, the mass ratio of the first ligand material MMES in the first developing solution to the mass of the red quantum dot matrix RQD in the second quantum dot solution is 2%; the mass ratio of the first ligand material MMES in the second developing solution to the mass of the red quantum dot matrix RQD in the second quantum dot solution is 5%; and the mass ratio of the first ligand material MMES in the third developing solution to the mass of the red quantum dot matrix RQD in the second quantum dot solution is 10%. The photoluminescence effect diagrams corresponding to the first, second, and third developing solutions are shown in Figure 14(a), Figure 14(b), and Figure 14(c), respectively.

[0332] As shown in Figure 14, the residual problem of quantum dot materials on the electron transport layer is significantly improved with the increase of the mass of the first ligand material MMES added to the PGMEA developer. This may be because the developer after adding the first ligand material MMES can undergo a dynamic ligand exchange reaction with the quantum dots in the luminescent film layer, displacing the quantum dot bulk material originally adsorbed on the electron transport layer in the unexposed area back into the developer.

[0333]

Example 5

[0334] In this embodiment, the sixth quantum dot solution, the seventh quantum dot solution, and the eighth quantum dot solution are spin-coated onto the electron transport layer containing zinc oxide / zinc magnesium oxide, and then developed with a developer.

[0335] The sixth, seventh, and eighth quantum dot solutions all include the red quantum dot matrix (RQD), the first ligand material (MMES), and a functional material, but the types of functional materials differ in each solution. Specifically, the sixth quantum dot solution contains a first functional material, and the solubilizing group is an ester group. Specifically, the first functional material is one or any combination of the first functional materials shown in formulas (a), (a1), (s), (d), and (g). The seventh quantum dot solution contains a second functional material, and the second coordinating group is a carboxyl group. Specifically, the second functional material is the second functional material shown in formula (b1). The eighth quantum dot solution contains a second functional material, and the second coordinating group is a thiol group. Each molecule of the second functional material contains one second coordinating group. Specifically, the second functional material is one or more combinations of the second functional materials shown in formulas (c) and (f).

[0336] Adding excessive amounts of the first ligand material MMES can hinder the overall carrier transport of the light-emitting device. Therefore, this embodiment proposes to synergistically add the first ligand material MMES and functional materials to the quantum dot solution. Adding the first ligand material MMES and functional materials can increase the dispersibility of the quantum dot bulk in the quantum dot solution, weakening the intermolecular interaction forces between quantum dot bulks, between the quantum dot bulk and the front film layer, and between the ligand material and the front film layer in a free or bonded manner, preventing particle aggregation, and thus achieving the purpose of improving the development effect.

[0337] Furthermore, in this embodiment, by appropriately reducing the amount of the first ligand material MMES and increasing the amount of functional material, the effects of preventing quantum dot material residue after development and improving carrier transport performance can be achieved. For example, by reducing the amount of the first ligand material MMES and increasing the amount of the first functional material, the first functional material can be directly used as a dispersant for the quantum dot solution; or, for another example, by reducing the amount of the first ligand material MMES and increasing the amount of the second functional material, the second functional material can undergo a dynamic ligand exchange reaction with the original ligand material connected to the quantum dot body, thereby passivating defects on the surface of the quantum dot body and increasing the dispersibility of the quantum dot body.

[0338]

Example 6

[0339] In this embodiment, a quantum dot solution is spin-coated onto an electron transport layer containing zinc oxide / zinc magnesium oxide, and then developed using a fourth developer, a fifth developer, and a sixth developer, respectively.

[0340] The fourth, fifth, and sixth developing solutions all include PGMEA, the first ligand material MMES, and functional materials, but the types of functional materials differ in each developing solution. Specifically, the functional material included in the fourth developing solution is a first functional material, and the solubilizing group is an ester group. Specifically, the first functional material is one or any combination of the first functional materials shown in formulas (a), (a1), (s), (d), and (g). The functional material included in the fifth developing solution is a second functional material, and the second coordinating group is a carboxyl group. Specifically, the second functional material is the second functional material shown in formula (b1). The functional material included in the sixth developing solution is a second functional material, the second coordinating group is a thiol group, and each molecule of the second functional material contains one second coordinating group. Specifically, the second functional material is one or more combinations of the second functional materials shown in formulas (c) and (f).

[0341] Adding excessive amounts of the first ligand material MMES can hinder the overall carrier transport of the light-emitting device. Therefore, this embodiment proposes to synergistically add the first ligand material MMES and the functional material to the developing solution. Adding the first ligand material MMES and the functional material can increase the dispersibility of the quantum dot bulk in the quantum dot solution, weakening the intermolecular interaction forces between quantum dot bulks, between quantum dot bulks and the front film layer, and between the ligand material and the front film layer in a free or bonded manner, preventing particle aggregation, and thus improving the developing effect.

[0342] Furthermore, in this embodiment, by appropriately reducing the amount of the first ligand material MMES and increasing the amount of functional material, the effects of preventing quantum dot material residue after development and improving carrier transport performance can be achieved. For example, by reducing the amount of the first ligand material MMES and increasing the amount of the first functional material, the first functional material can be directly used as a dispersant in the developer. Alternatively, by reducing the amount of the first ligand material MMES and increasing the amount of the second functional material, the second functional material can undergo a dynamic ligand exchange reaction with the original ligand material connected to the quantum dot matrix, thereby passivating defects on the surface of the quantum dot matrix and increasing the dispersibility of the quantum dot matrix.

[0343]

Example 7

[0344] In this embodiment, a ligand exchange process is used to prepare the quantum dot stock solution. Before the ligand exchange, the ligand material ligated to the quantum dot matrix is ​​the first ligand material MMES. After the ligand exchange, the ligand material ligated to the quantum dot matrix is ​​the first ligand material MMES and the second functional material. The second functional material may have a carboxyl group as a coordinating group; specifically, the second functional material is the second functional material shown in formula (b1). Alternatively, the second coordinating group may be a thiol group, and each molecule of the second functional material contains one thiol group. Specifically, the second functional material is one or more combinations of the second functional materials shown in formulas (c) and (f).

[0345] The molecular structure of the secondary functional material helps to disperse the quantum dot matrix in the quantum dot stock solution. The resulting dual-ligand quantum dot matrix has a certain steric hindrance, which can prevent particle aggregation and thus improve the development effect. Moreover, the secondary functional material contains a second aromatic amine group, which gives it a strong hole transport capability. Therefore, after the secondary functional material is bonded to the surface of the quantum dot matrix, it can help improve the hole injection effect, thereby mitigating the impact of the decrease in hole mobility caused by the photolithography process.

[0346]

Example 8

[0347] In this embodiment, a ninth quantum dot solution is spin-coated onto an electron transport layer containing zinc oxide / zinc magnesium oxide, and then developed with a developer.

[0348] The ninth quantum dot solution comprises a quantum dot bulk, a first ligand material MMES, and a third functional material. Specifically, the third functional material is one or more combinations of the third functional materials shown in formulas (c1) and (k).

[0349] In this embodiment, the third functional material can serve as a crosslinking material in the ninth quantum dot solution. The thiol groups contained in the third functional material can undergo a crosslinking reaction with the unsaturated carbon-carbon double bonds on the first ligand material MMES under ultraviolet light irradiation. In the photolithography process, it can bridge multiple quantum dot bodies to form a denser crosslinking network, enhancing the contrast between exposed and unexposed areas and optimizing the film retention effect after development. Moreover, the improved crosslinking ability can reduce the exposure dose in the photolithography process to a certain extent, weakening the destructive effect of strong exposure conditions on the light-emitting layer. In addition, the third functional material can also improve the problem of reduced mobility caused by the photolithography process.

[0350] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

A quantum dot material comprising: The quantum dot material includes a quantum dot body and a functional material; the functional material includes an aromatic amine group and a cosolvent group, the cosolvent group is used to increase the solubility of the functional material in a preset solvent, the ratio between the mass of the functional material and the mass of the quantum dot body is greater than 0 and less than or equal to 0.

45. The quantum dot material of claim 1, wherein, The preset solvent includes an ether group and / or an ester group. The quantum dot material according to claim 1 or 2, wherein, The functional material includes a first functional material, the first functional material includes a first aromatic amine group and the cosolvent group; The first functional material is not connected to the quantum dot body. The quantum dot material of claim 2, wherein, The ratio between the mass of the first functional material and the mass of the quantum dot body ranges from 0 to 0.

35. The quantum dot material according to any one of claims 1 to 4, wherein, The functional material includes a second functional material; the second functional material includes a second aromatic amine group, a second coordination group and the cosolvent group; The second functional material can be coordinated to the quantum dot body. The quantum dot material of claim 5, wherein, The second coordination group includes a carboxyl group and / or a mercapto group. The quantum dot material according to claim 5 or 6, wherein, The second functional material further includes a second photosensitive group. The quantum dot material according to any one of claims 1 to 7, wherein, Further included is a first ligand material, the first ligand material includes a first photosensitive group, and the first ligand material can be coordinated to the quantum dot body. The quantum dot material of claim 7 or 8, wherein, In the case where the second functional material includes a second photosensitive group, the second photosensitive group includes one or a combination of any multiple of an alkenyl group, an alkynyl group, a benzophenone group and an azido group; In the case where the quantum dot material includes a first ligand material, the first photosensitive group includes one or a combination of any multiple of an alkenyl group, an alkynyl group, a benzophenone group and an azido group. The quantum dot material according to any one of claims 5-9, wherein, In the case where the quantum dot material includes a first ligand material, the ratio between the mass of the first ligand material and the mass of the quantum dot body is greater than 0 and less than or equal to 0.45; In the case where the quantum dot material includes a first ligand material and a second functional material, the ratio between the mass of the first ligand material and the mass of the second functional material and the mass of the quantum dot body is greater than 0 and less than or equal to 0.

45. The quantum dot material according to any one of claims 7-10, wherein, The functional material includes a third functional material, the third functional material includes a third aromatic amine group, at least two initiation groups and the cosolvent group; In the case where the quantum dot material includes a first ligand material, the initiation group is configured to react with the first photosensitive group under light to form a cross-linked quantum dot material; In the case where the quantum dot material includes a second functional material and the second functional material includes a second photosensitive group, the initiation group is configured to react with the second photosensitive group under light to form a cross-linked quantum dot material; The solubility of the cross-linked quantum dot material in the preset solvent is less than the solubility of the quantum dot material in the preset solvent. The quantum dot material of claim 11, wherein, The initiation group includes a mercapto group. The quantum dot material according to claim 11 or 12, wherein, The ratio between the mass of the third functional material and the mass of the quantum dot body ranges from 0 to 0.

05. The quantum dot material according to any one of claims 2-13, wherein, The functional material is selected from any one of the structures shown in the general formula (I); wherein R1and R2are the same or different, and are each independently selected from any one of a substituted or unsubstituted C1-C10 alkylene, a substituted or unsubstituted C1-C10 alkylenoxy, a substituted or unsubstituted C3-C10 cycloalkylene, a substituted or unsubstituted C1-C10 heterocycloalkylene, a substituted or unsubstituted C6-C12 arylene, a substituted or unsubstituted C1-C12 heteroarylene, and a group comprising the cosmotonic group; R3-R8are the same or different, and are each independently selected from any one of hydrogen, deuterium, a substituted or unsubstituted C1-C10 alkyl, a substituted or unsubstituted C1-C10 alkoxy, a substituted or unsubstituted C3-C10 cycloalkyl, a substituted or unsubstituted C1-C10 heterocycloalkyl, a substituted or unsubstituted C6-C12 aryl, and a substituted or unsubstituted C1-C12 heteroaryl, and a group comprising the cosmotonic group; any two of n1, n2, m1, and m2are the same or different, and are each independently selected from any one of 0, 1, and 2, and the sum of n1and m1is 2, the sum of n2and m2is 2, and at least one of n1and n2is not 0; in the case that the functional material is a first functional material, at least one of X and R1-R8comprises the cosmotonic group; in the case that the functional material is a second functional material, X is the second coordination group, and at least one of R1-R8comprises the cosmotonic group; in the case that the functional material is a third functional material, the sum of n1and n2is greater than or equal to 2, X is the initiation group, and at least one of R1-R8comprises the cosmotonic group. The quantum dot material according to any one of claims 1 to 14, wherein, The functional material is selected from any one of the structures shown in the general formula (II); wherein R9is selected from any one of a substituted or unsubstituted C1-C10 alkylene, a substituted or unsubstituted C1-C10 alkylenoxy, a substituted or unsubstituted C3-C10 cycloalkylene, a substituted or unsubstituted C1-C10 heterocycloalkylene, a substituted or unsubstituted C6-C12 arylene, a substituted or unsubstituted C1-C12 heteroarylene, and a group comprising the cosmotonic group; p is selected from any one of 0, 1, and 2; q is selected from any one of 1, 2, and 3, and the sum of p and q is 3; in the case that the functional material is a first functional material, at least one of X and R9comprises the cosmotonic group; in the case that the functional material is a second functional material, X is the second coordination group, and R9comprises the cosmotonic group; in the case that the functional material is a third functional material, q is greater than or equal to 2, X is the initiation group, and at least one of R9connected to X comprises the cosmotonic group. The quantum dot material according to any one of claims 1 to 15, wherein, The cosmotonic group comprises an ester group and / or an ether group. A light-emitting device, comprising: oppositely disposed anode and cathode, and a light-emitting layer between the anode and the cathode; the material of the light-emitting layer comprises a crosslinked quantum dot material formed by the quantum dot material of any one of claims 1-16. The light emitting device according to claim 17, wherein The light-emitting device is disposed on a substrate; the cathode is closer to the substrate relative to the anode. The light emitting device according to claim 18, wherein The light-emitting device further comprises: An electron transport layer is located between the cathode and the light-emitting layer and is in contact with the light-emitting layer. A method for manufacturing a light-emitting device, comprising: forming a cathode, an anode and a light-emitting layer; the cathode is arranged opposite to the anode; the light-emitting layer is located between the anode and the cathode; wherein the material of the light-emitting layer comprises a crosslinked quantum dot material formed by a quantum dot material; the quantum dot material comprises a quantum dot body and a functional material; the functional material comprises an aromatic amine group and a cosolvent group, the cosolvent group is used to increase the solubility of the functional material in a predetermined solvent; the ratio between the mass of the functional material and the mass of the quantum dot body is greater than 0 and less than or equal to 0.

45. The method of producing a light emitting device according to claim 20, wherein The light-emitting device is formed on a substrate; forming the light-emitting layer, comprising: spinning the material of the initial light-emitting layer on the side of the cathode away from the substrate to form an initial light-emitting layer; the material of the initial light-emitting layer comprises the quantum dot material and the predetermined solvent; exposing the target area of the initial light-emitting layer, so that the material of the exposed part of the initial light-emitting layer is converted into the crosslinked quantum dot material; and, developing the initial light-emitting layer with a developing solution; the developing solution comprises the predetermined solvent. The method of producing a light emitting device according to claim 21, wherein The material for forming the initial light-emitting layer comprises: mixing the quantum dot body, an initial ligand material and the predetermined solvent to form a quantum dot stock solution; the ratio between the mass of the initial ligand material and the mass of the quantum dot body is greater than 0 and less than or equal to 0.13; wherein the initial ligand material comprises a first ligand material, the first ligand material can be ligated to the quantum dot body, and the first ligand material comprises a first photosensitive group; or, the initial ligand material comprises a second functional material, the second functional material can be ligated to the quantum dot body, and the second functional material comprises a second photosensitive group; the functional material comprises the second functional material; or, the initial ligand material comprises a first ligand material and a second functional material, the first ligand material and the second functional material can be ligated to the quantum dot body, the first ligand material comprises a first photosensitive group, and the functional material comprises the second functional material. The method of producing a light emitting device according to claim 22, wherein The material for forming the initial light-emitting layer further comprises: adding a first additional ligand material to the quantum dot stock solution; the ratio between the mass of the first additional ligand material and the mass of the quantum dot body ranges from 0 to 0.35; in the case where the initial ligand material comprises a first ligand material, the first additional ligand material comprises the first ligand material; in the case where the initial ligand material comprises a second functional material, the first additional ligand material comprises the second functional material. The method for manufacturing a light emitting device according to any one of claims 21 to 23, wherein The material of the initial light-emitting layer and / or the developing solution further comprises a first functional material; the functional material comprises the first functional material; and the first functional material is not connected to the quantum dot body. The method for manufacturing a light emitting device according to any one of claims 21 to 24, wherein The material of the initial light-emitting layer further comprises a third functional material; the functional material comprises the third functional material; and the third functional material comprises at least two initiation groups; In the case that the quantum dot material comprises a first ligand material, the initiating group is configured to react with the first photosensitive group under light irradiation to form the crosslinked quantum dot material from the quantum dot material; In the case that the quantum dot material comprises a second functional material, and the second functional material comprises a second photosensitive group, the initiating group is configured to react with the second photosensitive group under light irradiation to form the crosslinked quantum dot material from the quantum dot material. The method for manufacturing a light emitting device according to claims 21 to 25, wherein The developer further comprises a second additional ligand material; a ratio between a mass of the second additional ligand material in the developer and a mass of the quantum dot body in the material of the initial light-emitting layer ranges from 0 to 0.1; In the case that the initial ligand material comprises a first ligand material, the second additional ligand material comprises the first ligand material; In the case that the initial ligand material comprises a second functional material, the second additional ligand material comprises the second functional material.

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