Light-emitting layer forming material, preparation method of light-emitting layer, light-emitting device and display panel

Abstract

The embodiment of the invention provides a light-emitting layer forming material, a preparation method of a light-emitting layer, a light-emitting device and a display panel, relates to the technical field of display, and is used for simplifying a patterning process of the light-emitting layer of a QLED light-emitting device. The light-emitting layer forming material comprises a quantum dot material and a cross-linking material. The quantum dot material comprises a quantum dot body and a ligand material coordinated on the quantum dot body. The cross-linking material comprises at least two active groups, and the active groups are configured to react with the ligand material under a preset condition, so that the quantum dot material is converted into the cross-linking quantum dot material. The solubility of the cross-linked quantum dot material in the preset solvent is smaller than that of the quantum dot material in the preset solvent; wherein the ratio of the mass of the cross-linking material to the mass of the quantum dot material is greater than or equal to 0.005 and less than or equal to 0.05. The luminescent layer forming material is used for preparing a luminescent layer of a luminescent device.

Description

Technical Field

[0001] The present disclosure relates to the field of display technology, and in particular to a light-emitting layer forming material, a method for preparing the light-emitting layer, a light-emitting device and a display panel. Background Art

[0002] As a new type of luminescent material, quantum dots (QD) have the advantages of wide color gamut, high color purity, and continuously adjustable luminescence peak, and have become a research hotspot for new light-emitting diodes (LEDs). Therefore, quantum dot light-emitting diodes (QLEDs) with quantum dot materials as the luminescent layer have become the main research direction of new display devices.

[0003] In some implementations, the patterning process of the light-emitting layer of the QLED light-emitting device has the problem of complicated steps. Summary of the invention

[0004] The purpose of the embodiments of the present disclosure is to provide a light-emitting layer forming material, a method for preparing the light-emitting layer, a light-emitting device and a display panel, which are used to simplify the patterning process of the light-emitting layer of the QLED light-emitting device.

[0005] To achieve the above objectives, the embodiments of the present disclosure provide the following technical solutions:

[0006] On the one hand, a light-emitting layer forming material is provided. The light-emitting layer forming material includes a quantum dot material and a cross-linking material. The quantum dot material includes a quantum dot body and a ligand material coordinated to the quantum dot body. The cross-linking material includes at least two active groups, and the active groups are configured to react with the ligand material under preset conditions to convert the quantum dot material into a cross-linked quantum dot material. The solubility of the cross-linked quantum dot material in a preset solvent is less than the solubility of the quantum dot material in a preset solvent; wherein the ratio between the mass of the cross-linking material and the mass of the quantum dot material is greater than or equal to 0.005 and less than or equal to 0.05.

[0007] In the above-mentioned luminescent layer forming material, the connection between quantum dot material molecules can be achieved by using a cross-linking material, that is, a cross-linking effect is achieved to generate a cross-linked quantum dot material; and the quantum dot material that has not undergone a cross-linking reaction can be removed by using a preset solvent, so that the cross-linked quantum dot material is retained. Therefore, in the process of forming the luminescent layer, the luminescent layer forming material located in the target area can be treated under preset conditions, so that the quantum dot material in the luminescent layer forming material located in the target area undergoes a cross-linking reaction with the cross-linking material to generate a cross-linked quantum dot material; the luminescent layer forming material located outside the target area is not treated under preset conditions, so that the quantum dot material in the luminescent layer forming material located outside the target area does not undergo a cross-linking reaction with the cross-linking material, and then the luminescent layer forming material located outside the target area is removed by using a preset solvent, and the cross-linked quantum dot material located in the target area is retained, so that the purpose of patterning the luminescent layer can be achieved, and a high-resolution quantum dot pixel array can be obtained. Moreover, when the luminescent layer forming material is used to form the luminescent layer, no photoresist or other auxiliary materials are required, which can simplify the formation process of the luminescent layer and is conducive to industrial production.

[0008] In some embodiments, the preset condition includes irradiating ultraviolet light; or, the preset condition includes applying laser heating.

[0009] In some embodiments, the multiple active groups included in the cross-linking material are the same or different, and are independently selected from any one of a benzophenone group, an azide group, and a diaziridine group.

[0010] In some embodiments, the mass percentage of the ligand material in the quantum dot material is in the range of 15% to 25%.

[0011] In some embodiments, the preset conditions include irradiating ultraviolet light. The light-emitting layer forming material further includes: a photosensitive material. The photosensitive material is configured to: generate a free portion under the preset conditions; the free portion can be connected to the quantum dot body. The ratio between the mass of the photosensitive material and the mass of the quantum dot material is greater than or equal to 0.001 and less than or equal to 0.02.

[0012] In some embodiments, the cross-linked quantum dot material includes a quantum dot unit. The quantum dot unit includes a quantum dot body, a ligand material, and a free part, wherein the ligand material is coordinated to the quantum dot body, and the free part is connected to the quantum dot body. The polarity of the quantum dot unit is different from the polarity of the quantum dot material.

[0013] In some embodiments, the photosensitive material comprises a halogenated hydrocarbon and the dissociated moiety comprises a halogen.

[0014] In some embodiments, the photosensitive material includes at least one of a chlorinated hydrocarbon containing an aromatic group, a brominated hydrocarbon containing an aromatic group, and an iodinated hydrocarbon containing an aromatic group.

[0015] In some embodiments, the cross-linking material includes at least one of 4,4'-azidobiphenyl, 1,11-diazide-3,6,9-oxaundecane, 1,8-diazide-3,6-dioxaoctane, 1-azido-2-(2-azidoethoxy)ethane, 2,6-bis-(4-azidobenzylidene)cyclohexanone, and bis(4-(3-(trifluoromethyl)-3H-diazonyl-3-yl)benzyl)dodecanoate.

[0016] In some embodiments, the cross-linking material includes at least one of 3,3'-(4,4'-(butane-1,4-diyl)bis(4,1-phenyl))bis(3-(trifluoromethyl)-3H-bisaziridine), 3,3'-(4,4'-(perfluorobutane-1,4-diyl)bis(4,1-phenyl))bis(3-(trifluoromethyl)-3H-bisaziridine), 3,5-bis(3-(trifluoromethyl)-3H-bisaziridine-3-yl)pyridine and 3,3'-((perfluoropropane-2,2-diyl)bis(4,1-phenyl))bis(3-(trifluoromethyl)bisaziridine).

[0017] On the other hand, a method for preparing a light-emitting layer is provided. The preparation method comprises: providing a material for forming a light-emitting layer; the material for forming the light-emitting layer comprises a quantum dot material and a cross-linking material; the quantum dot material comprises a quantum dot body and a ligand material coordinated to the quantum dot body; the cross-linking material comprises at least two active groups; the ratio between the mass of the cross-linking material and the mass of the quantum dot material is greater than or equal to 0.005 and less than or equal to 0.05; and, under preset conditions, the active group reacts with the ligand material to convert the quantum dot material into a cross-linked quantum dot material.

[0018] The beneficial effects that can be achieved by the above-mentioned method for preparing the light-emitting layer are the same as the beneficial effects that can be achieved by the above-mentioned light-emitting layer forming material, and will not be described in detail here.

[0019] In some embodiments, the preset conditions include irradiating ultraviolet light. The light-emitting layer forming material also includes: a photosensitive material. The ratio between the mass of the photosensitive material and the mass of the quantum dot material is greater than or equal to 0.001 and less than or equal to 0.02. The preparation method also includes: under the preset conditions, the photosensitive material reacts to generate at least a free portion; the free portion can be connected to the quantum dot body.

[0020] In some embodiments, the preparation method further comprises: using a developer to develop the light-emitting layer forming material treated under preset conditions, wherein the developer comprises a preset solvent.

[0021] In another aspect, a light emitting device is provided, comprising: an anode, a cathode, and a light emitting layer located between the anode and the cathode, wherein a material for forming the light emitting layer comprises the light emitting layer forming material as described in any of the above embodiments.

[0022] The beneficial effects that can be achieved by the above-mentioned light-emitting device are the same as the beneficial effects that can be achieved by the above-mentioned light-emitting layer forming material, and will not be described in detail here.

[0023] In another aspect, a display panel is provided, wherein the display panel comprises: a light emitting device as described in any one of the above embodiments and a pixel driving circuit, wherein the pixel driving circuit is used to drive the light emitting device to emit light.

[0024] The beneficial effects that can be achieved by the above-mentioned display panel are the same as the beneficial effects that can be achieved by the above-mentioned light-emitting device, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the present disclosure, the following briefly introduces the drawings required to be used in some embodiments of the present disclosure. Obviously, the drawings described below are only drawings of some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can also be obtained based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams, and are not limitations on the actual size of the product involved in the embodiments of the present disclosure, the actual process of the method, the actual timing of the signal, etc.

[0026] Figure 1 is a structural diagram of a display panel according to some embodiments;

[0027] Figure 2A is a structural diagram of a display panel according to some further embodiments;

[0028] Figure 2B is a structural diagram of a display panel according to some further embodiments;

[0029] Figure 3 is a structural diagram of a display panel according to some further embodiments;

[0030] Figure 4 is a step diagram of a method for preparing a light-emitting layer according to some embodiments;

[0031] Figure 5 A schematic diagram of a reaction for cross-linking a quantum dot material according to some embodiments;

[0032] Figure 6 is a step diagram of a method for preparing a light-emitting layer according to some further embodiments;

[0033] Figure 7 is a flow chart of a method for preparing a light-emitting layer according to some embodiments;

[0034] Figure 8 is a photoluminescence image of a light-emitting layer according to some embodiments;

[0035] Fig. 9is a photoluminescence image of a light-emitting layer according to some embodiments;

[0036] Fig.10 is a structural diagram of a light-emitting substrate according to some embodiments;

[0037] Fig.11 FIG. 4 is an electroluminescent image of a light-emitting layer according to some embodiments. DETAILED DESCRIPTION

[0038] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present disclosure.

[0039] Unless the context requires otherwise, throughout the specification and claims, the term "including" is to be interpreted as an open, inclusive meaning, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "examples" or "some examples" and the like are intended to indicate that specific features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representations of the above terms do not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials or characteristics described may be included in any one or more embodiments or examples in any appropriate manner.

[0040] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0041] “At least one of A, B, and C” has the same meaning as “at least one of A, B, or C” and both include the following combinations of A, B, and C: A only, B only, C only, the combination of A and B, the combination of A and C, the combination of B and C, and the combination of A, B, and C.

[0042] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0043] The use of "adapted to" or "configured to" herein is meant to be open and inclusive language that does not exclude devices adapted or configured to perform additional tasks or steps.

[0044] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of variation from the particular value as determined by one of ordinary skill in the art taking into account the measurements in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0045] As used herein, "parallel", "perpendicular", and "equal" include the situations described and situations similar to the situations described, and the range of the similar situations is within the acceptable deviation range, wherein the acceptable deviation range is determined by a person of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallelism and approximate parallelism, wherein the acceptable deviation range of approximate parallelism may be, for example, a deviation within 5°; "perpendicular" includes absolute perpendicularity and approximate perpendicularity, wherein the acceptable deviation range of approximate perpendicularity may also be, for example, a deviation within 5°. "Equal" includes absolute equality and approximate equality, wherein the acceptable deviation range of approximate equality may be, for example, the difference between the two equalities is less than or equal to 5% of either one.

[0046] It will be understood that when a layer or an element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present between the layer or element and the other layer or substrate.

[0047] Exemplary embodiments are described herein with reference to cross-sectional views and / or plan views that are idealized exemplary drawings. In the drawings, the thickness of the layers and the area of ​​the regions are exaggerated for clarity. Therefore, variations in the shapes relative to the drawings due to, for example, manufacturing techniques and / or tolerances are conceivable. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown herein, but include shape deviations due to, for example, manufacturing. For example, an etched region shown as a rectangle will typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shapes of the regions of the device, and are not intended to limit the scope of the exemplary embodiments.

[0048] It should be noted that, for example, 11-1 in the drawings of the present disclosure indicates that component 11 belongs to component 1, and for example 121-12 indicates that electron injection layer 121 belongs to electron transport unit 12, and other similar numbers appearing in the drawings also follow the above description.

[0049] Some embodiments of the present disclosure provide a display panel 200. In some examples, such as Figure 1As shown, the display panel 200 includes a plurality of light-emitting devices 100 and a plurality of pixel driving circuits 231. In this case, the display panel 200 may also be referred to as an active display panel, such as an OLED (Organic Light Emitting Diode) display panel or a QLED panel.

[0050] In some other examples, the display panel 200 is a passive display panel, such as a liquid crystal display panel or a display panel including a photoluminescent device.

[0051] In the case where the display panel 200 is a QLED display panel, the light-emitting device 100 is a QLED light-emitting device. Among them, quantum dots (QD) are a semiconductor nanomaterial with a three-dimensional quantum confinement effect. When it is excited by energy (light or electricity), it will emit light of a specific wavelength according to its own characteristics. Therefore, quantum dots (QD) have excellent luminescence properties such as broadband absorption, narrowband emission, and continuously adjustable peak position, so that quantum dot light-emitting diodes (QLEDs) with quantum dots as luminescent materials can be used as a new type of light-emitting diode (LED), which has the advantages of high light color purity, high luminescence quantum efficiency, adjustable luminescence wavelength, and high photoluminescence quantum yield.

[0052] The above-mentioned display panel 200 can be applied to a display device. The display device can be any display device that displays whether it is moving (e.g., video) or fixed (e.g., still image) and whether it is text or image. More specifically, it is expected that the display panel of the embodiment can be implemented in or associated with a variety of electronic devices, such as (but not limited to) mobile phones, wireless devices, personal data assistants (PDAs), handheld or portable computers, GPS receivers / navigators, cameras, MP4 video players, cameras, game consoles, watches, clocks, calculators, TV monitors, flat panel displays, computer monitors, car displays (e.g., odometer displays, etc.), navigators, cockpit controllers and / or displays, displays of camera views (e.g., displays of rear-view cameras in vehicles), electronic photos, electronic billboards or signs, projectors, architectural structures, packaging and aesthetic structures (e.g., displays of images of a piece of jewelry), etc.

[0053] In some embodiments, Figure 1 As shown, the display panel 200 includes a substrate 210 and a light emitting functional layer 220 disposed on one side of the substrate 210 , and the light emitting functional layer 220 includes a plurality of light emitting devices 100 . That is, the plurality of light emitting devices 100 may be disposed on one side of the substrate 210 .

[0054] Exemplarily, the plurality of light emitting devices 100 may be arranged along the second direction Y, where the second direction Y is, for example, a direction parallel to the plane where the substrate 210 is located.

[0055] Exemplarily, the material of the substrate 210 may be a rigid material, such as glass, to realize a rigid substrate display; or, the material of the substrate 210 may also be a flexible material, such as polyimide (PI) or polyethylene glycol terephthalate (PET), to realize a flexible substrate display.

[0056] In some examples, such as Figure 1 As shown, the display panel 200 further includes a driving circuit layer 230 disposed between the substrate 210 and the light-emitting functional layer 220 , and the driving circuit layer 230 includes a plurality of pixel driving circuits 231 .

[0057] 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 lights emitted by the multiple light emitting devices 100 cooperate with each other, so that the display panel 200 realizes the display function.

[0058] In some examples, such as Figure 1 As shown, the display panel 200 further includes an encapsulation layer 240, which can be disposed on a 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 devices 100 to prevent moisture and oxygen in the external environment from entering the display panel 200, damaging the materials in the light-emitting devices 100 and shortening the life of the display panel 200.

[0059] In some embodiments, Figure 1 As shown, in the display panel 200 , the light-emitting functional layer 220 further includes a pixel defining layer 221 . The pixel defining layer 221 has a plurality of openings Q. The plurality of light-emitting devices 100 can be disposed in the plurality of openings Q in a one-to-one correspondence.

[0060] In some embodiments, Figure 2A and Figure 2B As shown, 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 arranged opposite to each other. The light emitting layer 13 is located between the anode 15 and the cathode 11.

[0061] For example, Figure 2A and Figure 2BAs shown, the anode 15 , the light emitting layer 13 , and the cathode 11 may be stacked along a first direction X, and the first direction X intersects with the second direction Y. For example, the second direction Y is perpendicular to the first direction X.

[0062] Based on the above structure, the light emitting principle of the light emitting device 100 is: through the circuit connected with the anode 15 and the cathode 11 (for example, the pixel driving circuit 231, such as Figure 1 ), the anode 15 is used to inject holes into the light-emitting layer 13, and the cathode 11 is used to inject electrons into the light-emitting layer 13. The injected electrons and holes form excitons (i.e., electron-hole pairs) in the light-emitting layer 13, and the excitons return to the ground state through radiation transition and emit photons.

[0063] Exemplarily, 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 be effectively migrated to the light-emitting layer 13 under the drive of the electric field, thereby combining with the electrons of 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 (Indium Tin Oxide, ITO) or indium zinc oxide (Indium Zinc Oxide, IZO). Alternatively, the material of the anode 15 can be a laminated structure, such as ITO / Ag / ITO, Ag / IZO, CNT / ITO, CNT / IZO, GO / ITO or GO / IZO, etc., wherein Ag is silver, CNT is carbon nanotube (Carbon nanotube), and GO is graphene oxide (graphene oxide). ITO / Ag / ITO means that the anode 15 includes three layers of thin films, and the materials of the three layers of thin films are ITO, Ag, and ITO respectively.

[0064] In some examples, the cathode 11 may be made of a material with a low work function, so that the electrons of the cathode 11 can be more easily injected into the electron transport unit 12, so that the electrons in the cathode 11 can be effectively migrated to the light-emitting layer 13 under the drive of the electric field, thereby recombining 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, such as 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) or lithium calcium magnesium alloy (Li:Ca:Al), etc.; or, the material of the cathode 11 can be a laminated structure, such as 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), etc. Among them, magnesium / aluminum (Mg / Al) means that the cathode 11 includes two thin films, and the materials of the two thin films are magnesium (Mg) and aluminum (Al), respectively.

[0065] In some examples, such as Figure 2A As shown in FIG. 1 , the anode 15 is closer to the substrate 210 than the cathode 11. In this case, the light emitting device 100 is a positive light emitting device. Figure 2B As shown, the cathode 11 is closer to the substrate 210 than the anode 15. In this case, the light emitting device 100 is an inverted light emitting device.

[0066] In some embodiments, Figure 2A , Figure 2B and Figure 3 As shown, 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, which is located on a 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, for example, includes at least one of a hole injection layer 141 (Hole Inject Layer, HIL3), a hole transport layer 142 (Hole Transport Layer, HTL) and an electron blocking layer (EBL) that are stacked. For example, Figure 3 As shown, the hole transport unit 14 includes a hole injection layer 141 and a hole transport layer 142 which are stacked in a direction away from the anode 15 .

[0067] In some embodiments, Figure 2A , Figure 2B and Figure 3 As shown in FIG. 1 and FIG. 2 , in order to improve the light emitting efficiency of the light emitting device 100, the light emitting device 100 further includes an electron transport unit 12, which is located on a 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, includes at least one of a stacked electron injection layer 121 (Electron Inject Layer, EIL), an electron transport layer (Electron Transport Layer, ETL) and a hole blocking layer (Hole Blocking Layer, EBL). For example, as Figure 3 As shown, the electron transport unit 12 includes an electron injection layer 121 .

[0068] By setting the film layers of the hole transport unit 14 and the electron transport unit 12, it is equivalent to setting transition steps between the anode 15 and the light-emitting layer 13 and between the cathode 11 and the light-emitting layer 13, thereby reducing the barrier height that the carrier transition needs to overcome, and making the light-emitting efficiency higher.

[0069] For example, the material of the hole transport layer 142 may be poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] (TFB).

[0070] For example, the material of the hole injection layer 141 may be poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT:PSS).

[0071] For example, the material of the electron injection layer 121 may be zinc oxide or magnesium zinc oxide, and the zinc oxide may be, for example, zinc oxide nanoparticles.

[0072] In order to realize the display panel 200 (see Figure 1 ), the display panel 200 includes a plurality of light-emitting devices 100, and the light-emitting colors of the plurality of light-emitting devices 100 are different. For example, the display panel 200 may include a red light-emitting device for emitting red light, a green light-emitting device for emitting green light, and a blue light-emitting device for emitting blue light. In this way, the brightness (gray scale) of the red light-emitting device, the green light-emitting device, and the blue light-emitting device can be adjusted respectively, and the display of multiple colors can be realized through color combination and superposition, thereby realizing full-color display of the display panel 200.

[0073] When the light emitting colors of the various light emitting devices 100 are different, the materials of the light emitting layers 13 included in the various light emitting devices 100 are different. When preparing the display panel 200, for a certain material of the light emitting layer 13, it is necessary to set the material of the light emitting layer 13 in a specified pixel opening Q (see Figure 1), even if some pixel openings Q contain the material of the light-emitting layer 13, other pixel openings Q do not contain the material of the light-emitting layer 13. Therefore, a patterning process is required to form the light-emitting layer 13 of the light-emitting device 100 so that the light-emitting layer 13 is formed in the specified pixel openings Q. Moreover, in the preparation method of the QLED light-emitting device, the patterning process of the light-emitting layer 13 (also referred to as the pixelization process) is a key process step for achieving high-resolution full-color QLED display.

[0074] In some embodiments, the patterning process of the light-emitting layer 13 is an inkjet printing process or a transfer process, but these processes are difficult to apply to the commercialization requirements of high-resolution QLED display panels.

[0075] In some other embodiments, the patterning process of the light emitting layer 13 is an indirect photolithography process. Figure 4 As shown, the formation process of the light emitting layer 13 includes steps R1 to R6, for example.

[0076] R1: Provide substrate K.

[0077] R2: Coat a photoresist layer J on one side of the substrate K.

[0078] Exemplarily, the substrate K includes a substrate 210 (see Figure 1 ) and a patterned anode layer disposed on one side of the substrate 210, the anode layer comprising a plurality of anodes 15 disposed at intervals (see Figure 2A In this case, the photoresist layer J may be coated on a side of the anode layer away from the substrate 210 .

[0079] Exemplarily, the substrate K may further include a driving circuit layer 230 located between the substrate 210 and the anode layer.

[0080] Exemplarily, the material of the photoresist layer J may be a positive photoresist or a negative photoresist. In the following, R3 to R6 are described exemplarily by taking the case where the material of the photoresist layer J is a negative photoresist as an example.

[0081] R3: UV exposure is performed on the target area W1 of the photoresist layer J.

[0082] Exemplarily, the mask N1 may be used to expose the target region W1 of the photoresist layer J and shield other regions of the photoresist layer J except the target region W1 (hereinafter referred to as non-target regions).

[0083] R4: Development, removing the portion of the photoresist layer J located in the non-target area, so that the portion of the photoresist layer J located in the target area W1 is retained.

[0084] R5: the side of the photoresist layer J retained in R4 that is away from the substrate K, and the exposed substrate K on which the material 13M of the light emitting layer 13 is coated.

[0085] R6: peeling the photoresist layer J from the substrate K, so that the material 13M of the light-emitting layer 13 on one side of the photoresist layer J is removed, and the material 13M of the light-emitting layer 13 on the substrate K is retained to form the light-emitting layer 13.

[0086] Compared with inkjet printing or transfer printing, the indirect photolithography process can obtain a smaller pixel size and achieve high resolution performance of the display panel. However, the indirect photolithography process requires the participation of photoresist, which has the following problems in practical application: when preparing QLED display panels for full-color display, the photoresist will be repeatedly applied, making the entire process cumbersome and not conducive to industrial production.

[0087] Based on this, some embodiments of the present disclosure provide a light-emitting layer forming material. Figure 5 As shown, the light-emitting layer forming material includes quantum dot material and cross-linking material. The quantum dot material includes a quantum dot body and a ligand material coordinated to the quantum dot body; the cross-linking material includes at least two active groups, and the active groups are configured to react with the ligand material under preset conditions to convert the quantum dot material into a cross-linked quantum dot material. The solubility of the cross-linked quantum dot material in a preset solvent is less than the solubility of the quantum dot material in a preset solvent. Wherein, the ratio between the mass of the cross-linking material and the mass of the quantum dot material is greater than or equal to 0.005 and less than or equal to 0.05.

[0088] In some examples, the quantum dot body can include any one or more of: II-VI quantum dots, III-V quantum dots, IV-VI quantum dots, IV quantum dots, I-III-VI quantum dots, I-II-IV-VI quantum dots, core-shell structured quantum dots, and ABX3 type perovskite quantum dots. Any combination.

[0089] Among them, the II-VI group quantum dots can be selected from: binary compounds such as one or more of CdS, CdSe, CdTe, ZnS, ZnO, ZnSe, ZnTe, HgSe, HgTe and HgS; ternary compounds such as one or more of HgxCd1-xTe, HgxCd1-xS, HgxCd1-xSe, HgxZn1-xTe, CdxZn1-xSe, CdxZn1-xS and ZnTeSe, wherein 0<x<1, but is not limited to this.

[0090] The III-V group quantum dots can be selected from: InP, InAs, InSb, GaAs, GaP, GaN, GaSb, GaNk, InN, AlP, AlN, AlAs, InGaAs, InGaN, or a mixture thereof; but are not limited thereto.

[0091] The IV-VI group quantum dots may be selected from: PbS, PbSe, PbTe, or a mixture thereof; but not limited thereto.

[0092] The quantum dots of core-shell structure refer to those in which one material is the core and the other material is the shell. For example, the quantum dots are CdS@ZnS, which means that the core material of the quantum dots is CdS and the shell material is ZnS. The quantum dots of core-shell structure can be selected from one or more of: CdS@ZnS, CdSe@CdS, InP@ZnS, CdTe@CdSe, CdSe@ZnTe, CdSe@ZnS, PdS@ZnS, ZnTe@CdSe, ZnSe@CdS and Cd1-xZnxS@ZnS, where 0<x<1, but not limited to this.

[0093] In ABX3 type perovskite quantum dots, A can be CH3NH3 + (methylamine), NH2CH=NH2(formamidine) and Cs + One or more of, B can be Pb 2+ and Sn 2+ One or two of the following, X can be Cl - Br - and I - One or more of the ABX3 type perovskite quantum dots may include CH3NH3PbBr3, CH3NH3PbCl3, CH3NH3PbI3, CsPbBr3, CsPbCl3 and CsPbI3, but are not limited thereto.

[0094] When multiple 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.

[0095] It should be understood that when the ligand material is coordinated to the quantum dot body, the ligand material contains a coordination group (also called an anchoring group) that can coordinate with the quantum dot body. The coordination group is, for example, any combination of one or more of a carboxyl group, a hydroxyl group, a phosphate group, and an amino group.

[0096] For example, in addition to the coordination group, the ligand material may further include a main chain connected to the coordination group, such as an alkane or an alkene.

[0097] Illustratively, the ligand material may include at least one of thiol compounds, oleic acid, and oleylamine.

[0098] The above-mentioned light-emitting layer forming material includes a quantum dot material and a cross-linking material. For example, the mass of the cross-linking material and / or the quantum dot material in the light-emitting layer forming material can be measured by a method such as a nuclear magnetic resonance (NMR) method or a Fourier transform infrared spectroscopy (FT-IR) method to obtain a ratio between the mass of the cross-linking material and the mass of the quantum dot material.

[0099] Illustratively, the ratio between the mass of the cross-linked material and the mass of the quantum dot material can be 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045 or 0.05, etc.

[0100] It should be understood that when the cross-linking material includes at least two active groups, the active groups are configured to react with the ligand material under preset conditions to convert the quantum dot material into a cross-linked quantum dot material. An active group of the cross-linking material molecule can react with the ligand material of a quantum dot material molecule, and another active group of the cross-linking material molecule can react with the ligand material of another quantum dot material molecule. In this way, the cross-linking material can be used to achieve connection between quantum dot material molecules, realize cross-linking, and generate cross-linked quantum dot materials.

[0101] Moreover, when the solubility of the cross-linked quantum dot material in the preset solvent is lower than the solubility of the quantum dot material in the preset solvent, the preset solvent can be used to remove the quantum dot material that has not undergone the cross-linking reaction, so that the cross-linked quantum dot material is retained.

[0102] It can be understood that through the above settings, the cross-linking material can be used to achieve the connection between quantum dot material molecules, achieve cross-linking, and generate cross-linked quantum dot materials; and the quantum dot materials that have not undergone cross-linking reaction can be removed by using a preset solvent, so that the cross-linked quantum dot materials are retained. In this way, in the process of forming the light-emitting layer, the light-emitting layer forming material located in the target area can be treated under preset conditions, so that the quantum dot materials in the light-emitting layer forming material located in the target area undergo cross-linking reaction with the cross-linking material to generate cross-linked quantum dot materials; the light-emitting layer forming material located outside the target area is not treated under preset conditions, so that the quantum dot materials in the light-emitting layer forming material located outside the target area do not undergo cross-linking reaction with the cross-linking material, and then the light-emitting layer forming material located outside the target area is removed by using a preset solvent, and the cross-linked quantum dot materials located in the target area are retained, so that the purpose of patterning the light-emitting layer can be achieved, and it is convenient to obtain a high-resolution quantum dot pixel array. Moreover, when the light-emitting layer forming material is used to form the light-emitting layer, no photoresist or other auxiliary materials are required, which can simplify the formation process of the light-emitting layer and is conducive to industrial production.

[0103] In some embodiments, the predetermined condition includes irradiating ultraviolet light.

[0104] Here, there is no limitation on the wavelength of the irradiated ultraviolet light, and the irradiated ultraviolet light may be ultraviolet light of a single wavelength band or ultraviolet light of multiple wavelength bands. For example, the preset condition may include irradiating ultraviolet light of 365 nm; for another example, the preset condition may include irradiating ultraviolet light of 254 nm; for another example, the preset condition may include irradiating ultraviolet light of 365 nm first and then irradiating ultraviolet light of 254 nm.

[0105] Through the above arrangement, the light-emitting layer forming material located in the target area can be irradiated with ultraviolet light, so that the quantum dot material in the light-emitting layer forming material located in the target area undergoes a cross-linking reaction with the cross-linking material. Moreover, ultraviolet light has the advantage of being shielded, so that the target area and the non-target area of ​​the light-emitting layer forming material can be divided by a shielding structure (for example, a mask plate or a mask layer), so that the ultraviolet light can irradiate the target area without irradiating the non-target area, so that the patterning of the light-emitting layer can be achieved. In addition, by selecting the cross-linking material, the light-emitting layer forming material can be made suitable for multi-band direct photolithography processes.

[0106] In some embodiments, the predetermined condition includes applying laser heating.

[0107] Here, there is no further limitation on the temperature of laser heating.

[0108] Through the above arrangement, the light-emitting layer forming material located in the target area can be laser-heated, so that the quantum dot material in the light-emitting layer forming material located in the target area and the cross-linking material undergo a cross-linking reaction. Moreover, the laser has the advantage of being shielded, so that the target area and the non-target area of ​​the light-emitting layer forming material can be divided by a shielding structure (for example, a mask plate or a mask layer), so that the laser can irradiate the target area without irradiating the non-target area, so that the patterning of the light-emitting layer can be achieved.

[0109] For a clearer explanation, the following takes the preset condition of irradiating ultraviolet light as an example to illustrate the method of preparing a patterned light-emitting layer using the above-mentioned light-emitting layer forming material (also referred to as direct photolithography). Figure 6 As shown, the process of forming the light emitting layer includes steps M1 to M4.

[0110] M1: Provide substrate K.

[0111] Exemplarily, the substrate K includes a substrate 210 (see Figure 1 ) and a patterned anode layer disposed on one side of the substrate 210, the anode layer comprising a plurality of anodes 11 disposed at intervals.

[0112] Exemplarily, the substrate K may further include a driving circuit layer 230 located between the substrate 210 and the anode layer.

[0113] M2: A light-emitting layer forming material is applied on one side of the substrate K to form an initial light-emitting layer 13i.

[0114] M3: UV exposure is performed on the target area W2 of the initial light-emitting layer 13i.

[0115] For example, the mask N2 may be used to expose the target region W2 of the initial light emitting layer 13 i and to shield other regions of the initial light emitting layer 13 i except the target region W2 .

[0116] It should be understood that under ultraviolet irradiation, the quantum dot material in the light-emitting layer forming material located in the target area W2 may undergo a cross-linking reaction with the cross-linking material to generate a cross-linked quantum dot material.

[0117] M4: development, removing the materials of the initial light-emitting layer 13 i located in other regions except the target region W2 , so that the materials of the initial light-emitting layer 13 i located in the target region W2 are retained, thereby forming the light-emitting layer 13 .

[0118] In some embodiments, the multiple active groups included in the cross-linking material are the same or different, and are independently selected from any one of a benzophenone group, an azide group, and a diaziridine group.

[0119] In some embodiments, the plurality of active groups included in the cross-linked material include benzophenone groups. In this case, the principle of the quantum dot material forming the cross-linked quantum dot material can be: the benzophenone groups are activated under light conditions. Under the condition of photolysis, a triplet ketone intermediate is generated, the structure of which is shown in the following formula: ● -O ● It will attack nearby CH bonds (for example, CH bonds in ligand materials), causing carbon-hydrogen insertion reactions, so that the quantum dot material forms cross-linked quantum dot materials.

[0120]

[0121] For example, in the case where the cross-linking material includes two benzophenone groups, the first benzophenone group of the cross-linking material can undergo a carbon-hydrogen insertion reaction with a ligand material of a quantum dot entity, and the second benzophenone group of the cross-linking material can undergo a carbon-hydrogen insertion reaction with a ligand material of another quantum dot entity, so that the two quantum dot entities are connected, thereby forming a cross-linked quantum dot material.

[0122] In some embodiments, the multiple active groups included in the cross-linked material include azide groups. In this case, the principle of the quantum dot material forming the cross-linked quantum dot material can be: the azide group is photolyzed under light conditions to generate an active intermediate free radical nitrogen carbene The nitrogen carbene will attack the nearby CH bond (for example, the CH bond in the ligand material), causing a carbon-hydrogen insertion reaction, so that the quantum dot material forms a cross-linked quantum dot material.

[0123] For example, in the case where the cross-linking material includes two azide groups, the first azide group of the cross-linking material can undergo a carbon-hydrogen insertion reaction with a ligand material of a quantum dot entity, and the second azide group of the cross-linking material can undergo a carbon-hydrogen insertion reaction with a ligand material of another quantum dot entity, so that the two quantum dot entities are connected, thereby forming a cross-linked quantum dot material.

[0124] In some embodiments, the crosslinking material comprises a plurality of reactive groups including diazirine groups. In this case, the principle of the quantum dot material forming a cross-linked quantum dot material can be: the diaziridine group is photolyzed under light conditions to generate an active intermediate free radical carbene The carbene will attack the nearby CH bonds (eg, the CH bonds in the ligand material), causing a carbon-hydrogen insertion reaction, so that the quantum dot material forms a cross-linked quantum dot material.

[0125] For example, in the case where the cross-linking material includes two diazirine groups, the first diazirine group of the cross-linking material can undergo a carbon-hydrogen insertion reaction with a ligand material of a quantum dot body, and the second diazirine group of the cross-linking material can undergo a carbon-hydrogen insertion reaction with a ligand material of another quantum dot body, thereby connecting the two quantum dot bodies and forming a cross-linked quantum dot material.

[0126] In some embodiments, the cross-linking material includes two or more active groups. For example, the cross-linking material includes an azide group and a diaziridine group, the azide group of the cross-linking material can undergo a carbon-hydrogen insertion reaction with a ligand material of a quantum dot body, and the diaziridine group of the cross-linking material can undergo a carbon-hydrogen insertion reaction with a ligand material of another quantum dot body, so that the two quantum dot bodies are connected, thereby forming a cross-linked quantum dot material.

[0127] It can be understood that by setting the active group to be any one of a benzophenone group, an azide group and a diaziridine group, the active group can undergo a carbon-hydrogen insertion reaction with the CH bond in the ligand material to achieve the connection between the quantum dot body and the cross-linking material, thereby converting the quantum dot material into a cross-linked quantum dot material.

[0128] In some embodiments, the cross-linking material includes at least one of 4,4'-azidobiphenyl, 1,11-diazide-3,6,9-oxaundecane, 1,8-diazide-3,6-dioxaoctane, 1-azido-2-(2-azidoethoxy)ethane, 2,6-bis-(4-azidobenzylidene)cyclohexanone, and bis(4-(3-(trifluoromethyl)-3H-diazonyl-3-yl)benzyl)dodecanoate.

[0129] In some examples, the crosslinking material includes one of the above materials, for example, the crosslinking material includes 4,4'-azidobiphenyl. In other examples, the crosslinking material includes any of the above materials, for example, the crosslinking material includes 4,4'-azidobiphenyl and 1,11-diazide-3,6,9-oxaundecane.

[0130] It can be understood that, on the one hand, through the above configuration, the cross-linking material includes a diazido material (i.e., a material containing two azide groups), so that the cross-linking material includes multiple active groups, so that the quantum dot material molecules can be connected by the cross-linking material, that is, the cross-linking effect is achieved to generate a cross-linked quantum dot material. On the other hand, the structures of the above materials are all short-chain molecular structures with small steric hindrance and have the advantage of being easy to obtain.

[0131] In some embodiments, the cross-linking material includes at least one of 3,3'-(4,4'-(butane-1,4-diyl)bis(4,1-phenyl))bis(3-(trifluoromethyl)-3H-bisaziridine), 3,3'-(4,4'-(perfluorobutane-1,4-diyl)bis(4,1-phenyl))bis(3-(trifluoromethyl)-3H-bisaziridine), 3,5-bis(3-(trifluoromethyl)-3H-bisaziridine-3-yl)pyridine and 3,3'-((perfluoropropane-2,2-diyl)bis(4,1-phenyl))bis(3-(trifluoromethyl)bisaziridine).

[0132] In some examples, the cross-linked material includes one of the above materials, for example, the cross-linked material includes 3,5-bis(3-(trifluoromethyl)-3H-bis(aziridine-3-yl)pyridine. In some other examples, the cross-linked material includes any of the above materials, for example, the cross-linked material includes 3,5-bis(3-(trifluoromethyl)-3H-bis(aziridine-3-yl)pyridine and 3'-((perfluoropropane-2,2-diyl)bis(4,1-phenyl))bis(3-(trifluoromethyl)bis(aziridine).

[0133] It can be understood that through the above-mentioned setting, the cross-linking material includes a bis(bis(aziridine)-based material (i.e., a material containing two bis(aziridine) groups), so that the cross-linking material includes multiple active groups. In this way, the cross-linking material can be used to achieve connection between quantum dot material molecules, that is, to achieve cross-linking and generate cross-linked quantum dot material.

[0134] In some embodiments, the mass percentage of the ligand material in the quantum dot material is in the range of 15% to 25%.

[0135] For example, the mass proportion of the ligand material in the quantum dot material may be 15%, 17%, 19%, 21%, 23% or 25%, etc.

[0136] For example, the mass of quantum dot material and / or ligand material in the light-emitting layer forming material can be measured by methods such as nuclear magnetic resonance (NMR) or Fourier transform infrared spectroscopy (FT-IR) to obtain the mass proportion of the ligand material in the quantum dot material.

[0137] It can be understood that when the mass proportion of the ligand material in the quantum dot material is low, the ligand material connected to the quantum dot body is less, the passivation effect of the ligand material on the surface defects of the quantum dot body is poor, and the ligand material that can participate in the reaction with the active groups of the cross-linking material is less; when the mass proportion of the ligand material in the quantum dot material is high, the content of the quantum dot body in the quantum dot material may be relatively low; therefore, by setting the mass proportion of the ligand material in the quantum dot material to 15% to 25%, the mass proportion of the ligand material in the quantum dot material can be within an appropriate range, and on the basis of ensuring the passivation effect of the ligand material on the surface defects of the quantum dot body and the high content of the quantum dot body in the quantum dot material, more ligand material can be made to react with the active groups of the cross-linking material, which is beneficial to the generation of cross-linked quantum dot materials, can improve the film retention rate in the process of preparing the light-emitting layer, and is beneficial to improving the patterning effect of the light-emitting layer.

[0138] In some embodiments, Figure 5 As shown, the preset conditions include irradiating ultraviolet light. The light-emitting layer forming material also includes: a photosensitive material. The photosensitive material is configured to: generate a free portion under the preset conditions; the free portion can be connected to the quantum dot body.

[0139] Here, there is no limitation on the structural form of the free part generated by the photosensitive material under preset conditions.

[0140] In some examples, the dissociated part generated by the photosensitive material under the preset conditions is a dissociated ion, in which case the dissociated part may also be referred to as a photogenerated ion. In some other examples, the dissociated part generated by the photosensitive material under the preset conditions is a free radical.

[0141] In some examples, the photosensitive material can generate acid under ultraviolet light conditions. In this case, the photosensitive material can also be called a photoacid generator.

[0142] Here, there is no limitation on the connection method between the free part generated by the photosensitive material under preset conditions and the quantum dot body.

[0143] In some examples, the free part generated by the photosensitive material under preset conditions is connected to the quantum dot body through a coordination bond. For example, the free part generated by the photosensitive material under preset conditions is a chloride ion, the quantum dot body is a cadmium-based quantum dot, and the chloride ion is connected to the cadmium-based quantum dot through a coordination bond. It should be understood that in the case where the free part is connected to the quantum dot body through a coordination bond, the free part can also undergo a ligand exchange reaction with a ligand material coordinated to the quantum dot body.

[0144] In some other examples, the free part generated by the photosensitive material under preset conditions is connected to the quantum dot body through an ionic bond. For example, the free part generated by the photosensitive material under preset conditions is chloride ions, the quantum dot body is a perovskite quantum dot, and the chloride ions are connected to the perovskite quantum dot through an ionic bond.

[0145] It can be understood that when the photosensitive material is configured to generate a free part under preset conditions, and the free part can be connected to the quantum dot body, the part of the surface defects of the quantum dot body that is not passivated by the ligand material can be connected to the free part generated by the photosensitive material under preset conditions to passivate some surface defects of the quantum dot body. In this way, the defects on the surface of the quantum dot body can be reduced, the stability of the quantum dots themselves can be improved, the pixel stability can be improved, the fluorescence efficiency can be improved, and the quantum yield can be improved, which is beneficial to ensuring the performance of the light-emitting device.

[0146] In some embodiments, the ratio between the mass of the photosensitive material and the mass of the quantum dot material is greater than or equal to 0.001 and less than or equal to 0.02.

[0147] For example, the ratio between the mass of the photosensitive material and the mass of the quantum dot material may be 0.001, 0.005, 0.01, 0.013, 0.015, 0.018 or 0.02, etc.

[0148] For example, the mass of quantum dot material and / or photosensitive material in the light-emitting layer forming material can be measured by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR) and the like to obtain the ratio between the mass of the photosensitive material and the mass of the quantum dot material.

[0149] When the ratio between the mass of the photosensitive material and the mass of the quantum dot material is low (for example, less than 0.001), the free part generated by the photosensitive material under preset conditions is relatively small, which may affect the effect of the free part on passivating the surface defects of the quantum dot body. When the ratio between the mass of the photosensitive material and the mass of the quantum dot material is high (for example, greater than 0.02), the free part generated by the photosensitive material under preset conditions is relatively large, which may make the amount of free part higher than the amount required to passivate the surface defects of the quantum dot body. Therefore, by setting the ratio between the mass of the photosensitive material and the mass of the quantum dot material to be greater than or equal to 0.001 and less than or equal to 0.02, the mass proportion of the photosensitive material in the light-emitting layer forming material can be within an appropriate range, which can improve the passivation effect of the photosensitive material on the surface defects of the quantum dot body.

[0150] It should be understood that when the solubility of the cross-linked quantum dot material in the developer (for example, including a preset solvent) is low, a relatively large amount of the cross-linked quantum dot material is retained after development, which can increase the film retention rate of the formed light-emitting layer and is beneficial to improving the patterning effect when forming the light-emitting layer.

[0151] In some embodiments, the developer (e.g., including a preset solvent) has a certain polarity, so that the polarity of the cross-linked quantum dot material affects the solubility of the cross-linked quantum dot material in the developer. In this way, the corrosion resistance of the cross-linked quantum dot material to the developer (e.g., including a preset solvent) can be increased by adjusting the polarity of the cross-linked quantum dot material, so as to improve the patterning effect when forming the light-emitting layer.

[0152] In some embodiments, Figure 5 As shown, the cross-linked quantum dot material includes a quantum dot unit. The quantum dot unit includes a quantum dot body, a ligand material and a free part, the ligand material is coordinated to the quantum dot body, and the free part is connected to the quantum dot body. The polarity of the quantum dot unit is different from the polarity of the quantum dot material.

[0153] The quantum dot unit can be understood as the part generated by the quantum dot material after the cross-linking reaction. In some examples, in addition to the quantum dot unit, the cross-linked quantum dot material also includes a cross-linking unit, which can be understood as the part generated by the cross-linking material after the cross-linking reaction.

[0154] In some examples, the free part generated by the photosensitive material changes the surface polarity of the quantum dot body by undergoing a coordination exchange reaction with the ligand material, so that the polarity of the quantum dot unit is different from the polarity of the quantum dot material. Alternatively, the free part generated by the photosensitive material can also change the surface polarity of the quantum dot body by connecting to the part of the surface of the quantum dot body where the ligand material is not provided, so that the polarity of the quantum dot unit is different from the polarity of the quantum dot material. Of course, the above two methods can occur at the same time.

[0155] It can be understood that when the free part generated by the photosensitive material under preset conditions is connected to the quantum dot body, the polarity of the free part will affect the polarity of the quantum dot unit (for example, the surface polarity of the quantum dot body), so that the polarity of the quantum dot unit is different from the polarity of the quantum dot material. In this way, the type of photosensitive material can be selected so that the polarity of the free part is within a suitable range. In this way, the polarity of the cross-linked quantum dot material can be adjusted by using the polarity of the free part to increase the corrosion resistance of the cross-linked quantum dot material to the developer (for example, including a preset solvent), which can improve the patterning effect when forming the light-emitting layer. Moreover, the ratio between the mass of the photosensitive material and the mass of the quantum dot material can be selected so that the amount of the free part generated by the photosensitive material under preset conditions is within a suitable range, which can further increase the feasibility of the free part to adjust the polarity of the cross-linked quantum dot material.

[0156] In some examples, the polarity of the quantum dot unit is less than the polarity of the quantum dot material. In this case, the free part generated by the photosensitive material under the preset conditions is a non-polar ion or a free radical with a smaller polarity.

[0157] In some other examples, the polarity of the quantum dot unit is greater than the polarity of the quantum dot material. In this case, the free part generated by the photosensitive material under the preset conditions is a polar ion or a free radical with a larger polarity.

[0158] In some embodiments, the photosensitive material comprises a halogenated hydrocarbon and the dissociated moiety comprises a halogen.

[0159] In some examples, the photosensitive material includes a fluorinated hydrocarbon, and the free moiety includes a fluoride ion or a fluoride radical.

[0160] In yet other examples, the photosensitive material includes a chlorinated hydrocarbon, and the free moiety includes chloride ions or chloride radicals.

[0161] In yet other examples, the photosensitive material includes a brominated hydrocarbon, and the free moiety includes a bromide ion or a bromine radical.

[0162] In yet other examples, the photosensitive material includes iodinated hydrocarbons, and the free moieties include iodine ions or iodine radicals.

[0163] It can be understood that when the photosensitive material includes halogenated hydrocarbons and the free part includes halogens, the free part has a larger polarity, which can make the polarity of the quantum dot unit greater than the polarity of the quantum dot material. Compared with the case where the cross-linked quantum dot material does not include a free part, the polarity of the cross-linked quantum dot material can be made larger, which can increase the corrosion resistance of the cross-linked quantum dot material to the developer (for example, including n-octane or toluene), and can improve the patterning effect when forming the light-emitting layer.

[0164] Here, the types and quantities of other groups in the halogenated hydrocarbon except the free part are not limited.

[0165] In some examples, the photosensitive material includes a halogenated aliphatic hydrocarbon, such as a halogenated straight-chain aliphatic hydrocarbon, a halogenated branched-chain aliphatic hydrocarbon, or a halogenated alicyclic hydrocarbon.

[0166] In some embodiments, the photosensitive material includes at least one of a chlorinated hydrocarbon containing an aromatic group, a brominated hydrocarbon containing an aromatic group, and an iodinated hydrocarbon containing an aromatic group.

[0167] In some examples, the photosensitive material includes one of the above materials, for example, the photosensitive material includes a chlorinated hydrocarbon containing an aromatic group. In other examples, the photosensitive material includes any of the above materials, for example, the photosensitive material includes a chlorinated hydrocarbon containing an aromatic group and a brominated hydrocarbon containing an aromatic group.

[0168] Illustratively, the photosensitive material includes a chlorinated hydrocarbon containing an aromatic group, such as diphenylmethane or triphenylmethane.

[0169] In some other examples, the photosensitive material includes a bromohydrocarbon containing an aromatic group, such as diphenylmethane bromide or triphenylmethane bromide.

[0170] In some other examples, the photosensitive material includes an iodinated hydrocarbon containing an aromatic group, such as an iodonium salt (such as a diaryl iodonium salt).

[0171] In the case where the photosensitive material includes at least one of chlorinated hydrocarbons containing aromatic groups, brominated hydrocarbons containing aromatic groups and iodinated hydrocarbons containing aromatic groups, the photosensitive material has the advantage of being easy to photolyze, which can reduce the difficulty of the photosensitive material generating free parts and enhance the effect of the photosensitive material in passivating surface defects of the quantum dot body and / or adjusting the polarity of the cross-linked quantum dot material.

[0172] The above is an exemplary description of the material for forming the light emitting layer. The following is an exemplary introduction to the method for preparing the light emitting layer 13.

[0173] Some embodiments of the present disclosure also provide a light-emitting layer 13 (see Figure 6 ) preparation method, such as Figure 7 As shown, the preparation method includes S1 to S2.

[0174] S1: Provide a light-emitting layer forming material; the light-emitting layer forming material includes a quantum dot material and a cross-linking material; the quantum dot material includes a quantum dot body and a ligand material coordinated to the quantum dot body; the cross-linking material includes at least two active groups; the ratio between the mass of the cross-linking material and the mass of the quantum dot material is greater than or equal to 0.005 and less than or equal to 0.05.

[0175] S2: Under preset conditions, the active group reacts with the ligand material to convert the quantum dot material into a cross-linked quantum dot material.

[0176] The beneficial effects that can be achieved by the above-mentioned method for preparing the light-emitting layer are the same as the beneficial effects that can be achieved by the above-mentioned light-emitting layer forming material, and will not be described in detail here.

[0177] In some embodiments, the preset condition includes irradiating ultraviolet light. The light-emitting layer forming material further includes: a photosensitive material. The ratio between the mass of the photosensitive material and the mass of the quantum dot material is greater than or equal to 0.001 and less than or equal to 0.02.

[0178] In this case, S2 of the above preparation method further includes: under preset conditions, the photosensitive material reacts to generate at least a free portion; the free portion can be connected to the quantum dot body.

[0179] Here, for the understanding of the photosensitive material and the free part, please refer to the description of the photosensitive material and the free part in the aforementioned part, which will not be repeated here.

[0180] Through the above arrangement, the part of the surface defects of the quantum dot body that is not passivated by the ligand material can be connected to the free part generated by the photosensitive material under preset conditions to passivate some of the surface defects of the quantum dot body. In this way, the defects on the surface of the quantum dot body can be reduced, the stability of the quantum dot itself can be improved, and the quantum yield can be improved. Moreover, as mentioned above, when the polarity of the quantum dot unit is different from the polarity of the quantum dot material, the polarity of the cross-linked quantum dot material can be adjusted by using the polarity of the free part, which can increase the corrosion resistance of the cross-linked quantum dot material to the developer (for example, including a preset solvent) to improve the patterning effect when forming the light-emitting layer.

[0181] In some embodiments, after S2, the preparation method further includes S3.

[0182] S3: using a developer to develop the light-emitting layer forming material treated under preset conditions, wherein the developer includes a preset solvent.

[0183] Exemplarily, the preset solvent includes toluene and / or n-octane.

[0184] By setting the developer to include a preset solvent, the solubility of the cross-linked quantum dot material in the developer can be made lower than the solubility of the quantum dot material in the developer. In this way, by developing the light-emitting layer-forming material treated under the preset conditions, such as Figure 6 As shown, the quantum dot materials located in the target area W2 and the non-target area can be removed, so that the cross-linked quantum dot materials located in the target area W2 are retained to form the light-emitting layer 13, which can improve the patterning effect when forming the light-emitting layer 13.

[0185] Hereinafter, the technical solution provided by the present disclosure will be described in detail and exemplarily through the following experimental examples.

[0186] [Example 1]

[0187] The following examples prepare the light-emitting layer. The preparation method includes P1 to P6.

[0188] P1: Prepare quantum dot solution. The solvent of the quantum dot solution is n-octane, and the solute of the quantum dot solution is quantum dot material. The quantum dot material includes red quantum dot body and ligand material, and the ligand material includes thiol, oleic acid or oleylamine. The concentration of quantum dot material in the quantum dot solution is 20 mg / mL.

[0189] P2: Adding photosensitive material diphenylmethane and cross-linking material 4,4'-azidobiphenyl to the quantum dot solution to form a light-emitting layer forming material, wherein the ratio between the mass of the photosensitive material diphenylmethane and the mass of the quantum dot material is 0.005, and the ratio between the mass of the cross-linking material 4,4'-azidobiphenyl and the mass of the quantum dot material is 0.02.

[0190] P3: Coating the light-emitting layer forming material on the substrate to form an initial light-emitting layer.

[0191] P4: Use a mask plate to block other areas of the initial light-emitting layer except the target area to expose the target area.

[0192] P5: The target area of ​​the initial light-emitting layer is irradiated with ultraviolet light, and the wavelength of the irradiated ultraviolet light is 254nm.

[0193] P6: The initial light-emitting layer irradiated with ultraviolet light is developed using n-octane to obtain a patterned light-emitting layer.

[0194] The photoluminescence image of the patterned light-emitting layer obtained in P6 is as follows: Figure 8 As shown. Figure 8 It can be seen that by using the above-mentioned light-emitting layer forming material, a quantum dot pixel array can be obtained.

[0195] [Example 2]

[0196] The following examples prepare the light-emitting layer. The preparation method includes V1 to V6.

[0197] V1: Prepare quantum dot solution. The solvent of quantum dot solution is n-octane, and the solute of quantum dot solution is quantum dot material. Quantum dot material includes red quantum dot body and ligand material, and ligand material includes thiol, oleic acid or oleylamine, etc. The concentration of quantum dot material in quantum dot solution is 20mg / mL.

[0198] V2: Adding the photosensitive material diphenylmethane and the cross-linking material 3,3'-(4,4'-(butane-1,4-diyl)bis(4,1-phenyl))bis(3-(trifluoromethyl)-3h-diaziridine) to the quantum dot solution to form a light-emitting layer forming material. The ratio between the mass of the photosensitive material diphenylmethane and the mass of the quantum dot material is 0.005, and the ratio between the mass of the cross-linking material 3,3'-(4,4'-(butane-1,4-diyl)bis(4,1-phenyl))bis(3-(trifluoromethyl)-3h-diaziridine) and the mass of the quantum dot material is 0.02.

[0199] V3: Coating the light-emitting layer forming material on the substrate to form an initial light-emitting layer.

[0200] V4: Use a mask plate to block other areas of the initial light-emitting layer except the target area to expose the target area.

[0201] V5: The target area of ​​the initial light-emitting layer is irradiated with ultraviolet light, and the wavelength of the irradiated ultraviolet light is 365nm.

[0202] V6: The initial light-emitting layer irradiated with ultraviolet light is developed using n-octane to obtain a patterned light-emitting layer.

[0203] The photoluminescence image of the patterned light-emitting layer obtained in V6 is shown in FIG. Fig. 9 As shown. Fig. 9 It can be seen that by using the above-mentioned light-emitting layer forming material, a quantum dot pixel array can be obtained.

[0204] [Example 3]

[0205] The following embodiment prepares a light-emitting substrate 300, and the structure of the light-emitting substrate 300 is as follows: Fig.10 The preparation method includes U1 to U2.

[0206] U1: Provide an ITO substrate K', wherein the ITO substrate K' comprises a substrate and an anode layer disposed on one side of the substrate, and further comprises a driving circuit layer located between the substrate and the anode layer.

[0207] U2: A hole injection layer 141 and a hole transport layer 142 are sequentially formed on one side of the ITO substrate K' by spin coating. The material of the hole injection layer 141 is PEDOT:PSS, and the material of the hole transport layer 142 is TFB.

[0208] U3: Provide a light-emitting layer forming material; specifically, the process includes: first, preparing a quantum dot solution. The solvent of the quantum dot solution is toluene, and the solute of the quantum dot solution is a quantum dot material. The quantum dot material includes a red quantum dot body and a ligand material, and the ligand material includes thiol, oleic acid or oleylamine, etc. The concentration of the quantum dot material in the quantum dot solution is 20 mg / mL. Then, a photosensitive material triphenylmethane bromide and a cross-linking material are added to the quantum dot solution to form a light-emitting layer forming material. Among them, the ratio between the mass of the photosensitive material triphenylmethane bromide and the mass of the quantum dot material is 0.005, and the ratio between the mass of the cross-linking material and the mass of the quantum dot material is 0.01. The cross-linking material is a material containing multiple azide groups in the molecule.

[0209] U4: A light-emitting layer forming material is applied to the side of the hole transport layer 142 away from the hole injection layer 141 to form an initial light-emitting layer.

[0210] U5: Use a mask plate to shield the other areas of the initial light-emitting layer except the target area to expose the target area. Then, the target area of ​​the initial light-emitting layer is irradiated with ultraviolet light, and the wavelength of the irradiated ultraviolet light is 254nm.

[0211] U6: The initial light-emitting layer irradiated with ultraviolet light is developed using toluene to obtain a patterned light-emitting layer 13 .

[0212] U7: Using a spin coating process, an electron injection layer 121 is formed on the side of the light-emitting layer 13 away from the hole transport layer 142 . The material of the electron injection layer 121 is ZnO nanoparticles.

[0213] U8: A cathode layer 11A is formed on the side of the electron injection layer 121 away from the light-emitting layer 13 by using an evaporation process. The material of the cathode layer 11A is silver (Ag).

[0214] U9: Encapsulated with glass cover.

[0215] The prepared light-emitting substrate 300 was tested for lighting, and the results were as follows: Fig.11 As shown. Fig.11 It can be seen that by using the above-mentioned light-emitting layer forming materials, an arrayed QLED electroluminescent device can be obtained.

[0216] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be thought of by any person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A light-emitting layer forming material, characterized in that: include: Quantum dot material and cross-linking material; the quantum dot material includes a quantum dot body and a ligand material coordinated to the quantum dot body; the cross-linking material includes at least two active groups, and the active groups are configured to: react with the ligand material under preset conditions to convert the quantum dot material into a cross-linked quantum dot material; the solubility of the cross-linked quantum dot material in a preset solvent is less than the solubility of the quantum dot material in the preset solvent; Wherein, the ratio between the mass of the cross-linking material and the mass of the quantum dot material is greater than or equal to 0.005 and less than or equal to 0.

05.

2. The light-emitting layer forming material according to claim 1, characterized in that The preset condition includes irradiating ultraviolet light; or, the preset condition includes applying laser heating means.

3. The light-emitting layer forming material according to claim 1, characterized in that The multiple active groups included in the cross-linking material are the same or different, and are independently selected from any one of a benzophenone group, an azide group and a diaziridine group.

4. The light-emitting layer forming material according to claim 1, characterized in that The mass proportion of the ligand material in the quantum dot material is in the range of 15% to 25%.

5. The light-emitting layer forming material according to any one of claims 1 to 4, characterized in that The preset conditions include irradiating ultraviolet light; The light-emitting layer forming material further includes: a photosensitive material; the photosensitive material is configured to: generate a free portion under the preset conditions; the free portion can be connected to the quantum dot body; The ratio between the mass of the photosensitive material and the mass of the quantum dot material is greater than or equal to 0.001 and less than or equal to 0.

02.

6. The light-emitting layer forming material according to claim 5, characterized in that The cross-linked quantum dot material includes a quantum dot unit, the quantum dot unit includes the quantum dot body, the ligand material and the free part, the ligand material is coordinated to the quantum dot body, and the free part is connected to the quantum dot body; The polarity of the quantum dot unit is different from the polarity of the quantum dot material.

7. The light-emitting layer forming material according to claim 5, characterized in that The photosensitive material includes a halogenated hydrocarbon, and the dissociated portion includes a halogen.

8. The light-emitting layer forming material according to claim 7, characterized in that The photosensitive material includes at least one of chlorohydrocarbon containing an aromatic group, bromohydrocarbon containing an aromatic group, and iodohydrocarbon containing an aromatic group.

9. The light-emitting layer forming material according to any one of claims 1 to 4, characterized in that The cross-linking material includes at least one of 4,4'-azidobiphenyl, 1,11-diazide-3,6,9-oxaundecane, 1,8-diazide-3,6-dioxaoctane, 1-azido-2-(2-azidoethoxy)ethane, 2,6-bis-(4-azidobenzylidene)cyclohexanone and bis(4-(3-(trifluoromethyl)-3H-diazonyl-3-yl)benzyl)dodecanoate.

10. The light-emitting layer forming material according to any one of claims 1 to 4, characterized in that The cross-linking material includes at least one of 3,3'-(4,4'-(butane-1,4-diyl)bis(4,1-phenyl))bis(3-(trifluoromethyl)-3H-bisaziridine), 3,3'-(4,4'-(perfluorobutane-1,4-diyl)bis(4,1-phenyl))bis(3-(trifluoromethyl)-3H-bisaziridine), 3,5-bis(3-(trifluoromethyl)-3H-bisaziridine-3-yl)pyridine and 3,3'-((perfluoropropane-2,2-diyl)bis(4,1-phenyl))bis(3-(trifluoromethyl)bisaziridine).

11. A method for preparing a light-emitting layer, characterized in that: include: providing a light-emitting layer forming material; The light-emitting layer forming material includes quantum dot material and cross-linking material; The quantum dot material includes a quantum dot body and a ligand material coordinated to the quantum dot body; the cross-linking material includes at least two active groups; the ratio between the mass of the cross-linking material and the mass of the quantum dot material is greater than or equal to 0.005 and less than or equal to 0.05; and, Under preset conditions, the active group reacts with the ligand material to convert the quantum dot material into the cross-linked quantum dot material.

12. The method for preparing a light-emitting layer according to claim 11, characterized in that: The preset conditions include irradiating ultraviolet light; the light-emitting layer forming material further includes: a photosensitive material; the ratio between the mass of the photosensitive material and the mass of the quantum dot material is greater than or equal to 0.001 and less than or equal to 0.02; The preparation method further comprises: Under the preset conditions, the photosensitive material reacts to generate at least a free portion; the free portion can be connected to the quantum dot body.

13. The method for preparing a light-emitting layer according to claim 11 or 12, characterized in that: The preparation method further comprises: The light-emitting layer forming material treated under the preset conditions is developed using a developer, wherein the developer includes the preset solvent.

14. A light emitting device, characterized in that: The invention comprises an anode, a cathode and a light-emitting layer located between the anode and the cathode; the material forming the light-emitting layer comprises the light-emitting layer forming material according to any one of claims 1 to 10.

15. A display panel, characterized in that: include: The light emitting device according to claim 14; The pixel driving circuit is used to drive the light emitting device to emit light.

Images