Quantum dot inks, thin films and their preparation methods, optoelectronic devices and display devices

Abstract

This application discloses a quantum dot ink, a thin film, a method for preparing the same, an optoelectronic device, and a display device. The quantum dot ink comprises quantum dots, upconversion particles, a photocrosslinking agent, and a solvent. The quantum dot ink described in this application can be used to prepare thin films using photolithography, and the prepared thin films exhibit high fluorescence quantum yield.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to a quantum dot ink, a thin film and its preparation method, an optoelectronic device and a display device. Background Technology

[0002] Quantum dots (QDs), also known as semiconductor nanocrystals, possess unique luminescent properties, such as broad excitation peaks, narrow emission peaks, and tunable emission spectra, making them promising candidates for applications in the field of optoelectronics. Quantum dot films are typically prepared from quantum dot inks through film-forming processes.

[0003] The fluorescence quantum yield of thin films prepared by photolithography using existing quantum dot inks is low and needs further improvement. Summary of the Invention

[0004] In view of this, this application provides a quantum dot ink, a thin film, a method for preparing the same, an optoelectronic device, and a display device.

[0005] This application provides a quantum dot ink, comprising quantum dots, upconversion particles, a photocrosslinking agent, and a solvent.

[0006] Accordingly, embodiments of this application also provide a thin film comprising a mesh framework and quantum dots and upconversion particles filled in the mesh framework, wherein the material of the mesh framework comprises cross-linked molecules.

[0007] Accordingly, embodiments of this application also provide a method for preparing a thin film, comprising the following steps:

[0008] The quantum dot ink is provided, and the quantum dot ink is deposited on a substrate to obtain a preform film;

[0009] The pre-fabricated film is subjected to photolithography to obtain a thin film.

[0010] Accordingly, this application also provides an optoelectronic device, including a stacked anode, a light-emitting layer, and a cathode, wherein the light-emitting layer is the thin film, or the light-emitting layer is a thin film prepared by the preparation method described above.

[0011] Accordingly, embodiments of this application also provide a display device, including the aforementioned optoelectronic device.

[0012] The quantum dot ink described in this application can be used to prepare thin films using photolithography, and the prepared thin films have a high fluorescence quantum yield. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a flowchart of a thin film preparation method provided in an embodiment of this application;

[0015] Figure 2 This is a schematic diagram of the structure of an optoelectronic device provided in an embodiment of this application.

[0016] Figure label:

[0017] Optoelectronic device 100; anode 10; light-emitting layer 20; cathode 30; electron transport layer 40; hole transport layer 50; hole injection layer 60. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0019] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order.

[0020] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0021] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0022] In this application, the term "on" forming another layer on a certain layer is a broad concept. It can mean that the formed other layer is adjacent to a certain layer, or it can mean that there are other spacer structures between the other layer and the certain layer. For example, when a second electrode is formed "on" a first charge carrier functional layer, the term "on" can mean that the formed second electrode is adjacent to the first charge carrier functional layer, or it can mean that there are other spacer structures between the second electrode and the first charge carrier functional layer, such as a light-emitting layer.

[0023] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0024] In this application, the thickness of the film was measured using a step tester, and the particle size was measured using a transmission electron microscope (TEM).

[0025] QLED (quantum dot light-emitting diode) based light-emitting display technology is currently the most promising new display technology. After more than 20 years of development, QLED technology has made great progress in performance indicators and has also shown great potential for application development. Existing quantum dot thin film patterning methods include low-resolution photolithography, non-destructive inkjet printing, and high-resolution photolithography.

[0026] Photolithography processes for high-resolution applications involve attaching photosensitive ligands to the surface of quantum dots or adding photosensitive molecules to quantum dot ink to form a quantum dot film, followed by photolithographic patterning. In the exposed areas, under high-energy light, the photosensitive molecules undergo cross-linking reactions with themselves or with the ligands on the quantum dot surface, generating an anti-solvent effect. Solvent development is then used to obtain the patterned quantum dot film. However, because the exposure process often uses short-wavelength, high-energy ultraviolet light to treat the quantum dot film, it can damage the fluorescence and surface structure of the quantum dot nanocrystals, leading to a decrease in fluorescence quantum yield and a certain degree of performance degradation.

[0027] The technical solution of this application is as follows:

[0028] This application provides a quantum dot ink, comprising quantum dots, upconversion particles, a photocrosslinking agent, and a solvent, wherein organic ligands are coordinated to the surface of the quantum dots.

[0029] The quantum dot ink described in this application includes the upconversion particles and the photocrosslinking agent. The upconversion particles can absorb low-energy light (long-wavelength light) and convert it into high-energy light (short-wavelength light) that can be photolithographically processed into quantum dot films. During this process, the photo-induced photocrosslinking agent obtained by the upconversion particles in the quantum dot film undergoes a crosslinking reaction with the organic ligands on the surface of the quantum dots. Thus, when using the quantum dot ink to prepare patterned films, long-wavelength, low-energy near-infrared light can be used for photolithography. This effectively avoids direct damage to the quantum dots in the emitting layer caused by the full coverage of the high-energy light source, thereby effectively improving the fluorescence quantum yield of the film.

[0030] Furthermore, the thin film prepared from the quantum dot ink contains the upconversion particles, which are narrow bandgap materials and can act as carrier transport media within the thin film. This can effectively reduce the carrier transport barrier between quantum dots, thereby further improving the fluorescence quantum yield of the thin film.

[0031] In some embodiments, the concentration of quantum dots in the quantum dot ink ranges from 10 to 100 mg / mL, for example, 10 mg / mL, 20 mg / mL, 30 mg / mL, 40 mg / mL, 50 mg / mL, 60 mg / mL, 70 mg / mL, 80 mg / mL, 90 mg / mL, 100 mg / mL, and any range between two of these values. Within this range, the quantum dot ink can exhibit good dispersibility and film-forming properties.

[0032] In some embodiments, the mass ratio of the quantum dots to the photocrosslinking agent is 1:(0.01 to 0.1), for example, 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.1, and any range between these two ratios. Within this ratio range, during film formation, it is beneficial for the quantum dots to be fully crosslinked, resulting in a film with high solvent resistance, and also for the film to have good conductivity, thereby facilitating the transport of charge carriers within the film layer.

[0033] In some embodiments, the mass ratio of the quantum dot to the upconversion particle is 1:(0.05–0.2), for example, 1:0.05, 1:0.06, 1:0.08, 1:0.1, 1:0.12, 1:0.13, 1:0.15, 1:0.16, 1:0.18, 1:0.2, and any range between these two ratios. Within this range, it is advantageous to absorb a sufficient amount of long-wavelength light (low-energy light) and convert it into short-wavelength light (high-energy light) that can promote photocrosslinking, while also ensuring that the thin film has good luminescent properties.

[0034] The photocrosslinking agent comprises a crosslinking group capable of undergoing a crosslinking reaction with organic ligands on the surface of quantum dots. It should be understood that the crosslinking group can be any suitable photoresponsive crosslinking group capable of undergoing a crosslinking reaction under UV light irradiation. The free radicals generated by the crosslinking group of the photocrosslinking agent can undergo CH insertion and / or NH insertion reactions with the organic ligands on the surface of quantum dots, thereby crosslinking the quantum dots and thus forming a more stable film when using the quantum dot ink to prepare the film.

[0035] In some embodiments, the photocrosslinker includes, but is not limited to, one or more of azide-based photocrosslinkers, organophosphorus photocrosslinkers, diazonium pyrazine, and triphenylmethyl chloride.

[0036] In some embodiments, the azide compound photocrosslinker includes, but is not limited to, one or more of aryl azide compound photocrosslinkers and alkyl azide compound photocrosslinkers. The aryl azido compound photocrosslinking agents include, but are not limited to, one or more of the following: ethane-1,2-dimethylbis(4-azido-2,3,5,6-tetrafluorobenzoate) (CAS: 129835-91-2), 6-[(4-azido-2-nitrophenyl)amino]hexanoic acid sulfonate succinimide ester (CAS: 102568-43-4), sodium 4,4'-diazidostilbene-2,2'-disulfonate (CAS: 2718-90-3), 4-azidobenzaldehyde (CAS: 24173-36-2), 2,6-bis(4-azidobenzylidene)-4-methylcyclohexanone (BAMC, CAS: 5284-79-7), and 4-(P-azidosalicylic acid)-butylamine (ASBA, CAS: 176049-73-3). The alkyl azido compound photocrosslinking agents include, but are not limited to, one or more of the following: azido-tetraethylene glycol-amino (N3-PEG4-NH2, CAS: 951671-92-4), 3-(2-azidoethyl)-3-methyl-3H-diazine (CAS: 1800541-83-6), 3-azido-1-propanol (CAS: 72320-38-8), 3,3-bis(azidomethyl)thionecyclobutane 1,1-dioxide (CAS: 1422496-57-8), 1,5-bisazido-3-oxapentane (CAS: 24345-74-2), and 1,11-diazido-3,6,9-trioxaundecanane (CAS: 101187-39-7).

[0037] It should be noted that the aryl azide compound photocrosslinking agent in this application refers to a photocrosslinking agent containing a structure in which an azide group and an aryl group are directly linked, and the alkyl azide compound photocrosslinking agent in this application refers to a photocrosslinking agent containing a structure in which an azide group and an alkyl or alkylene group are directly linked.

[0038] In some embodiments, the organophosphorus photocrosslinker includes, but is not limited to, one or more of diphenylphosphine, triphenylphosphine, and tris(dipyridyl)phosphine.

[0039] The azide compound photocrosslinking agent described in this application can be activated into nitrogen free radicals by ultraviolet light irradiation, and then form chemical bonds with alkyl groups in the molecular chains of ligands on the surface of adjacent quantum dots, thereby achieving crosslinking between quantum dots and then curing them into a film.

[0040] The organophosphorus photocrosslinking agent described in this application can be activated into phosphorus free radicals by ultraviolet light irradiation, and then form chemical bonds with alkyl groups in the molecular chains of ligands on the surface of adjacent quantum dots, thereby achieving crosslinking between quantum dots and curing them into a film.

[0041] The upconversion particles include one or more of mononuclear upconversion particles and core-shell nanostructured upconversion particles. The core-shell nanostructured upconversion particles comprise one or more shell layers. The materials of the mononuclear upconversion particles, the core material of the core-shell nanostructured upconversion particles, and the shell materials of the core-shell nanostructured upconversion particles are each independently including, but are not limited to, rare earth element-doped materials such as NaYbF4, NaLuF4, NaGaF4, NaErF4, NaYF4, CaF2, Gd2(MoO4)3, Y2O3, Gd2O2S, BaY2F8, LiNbO3, Gd2O2, and Y3Al5O3. 12 The rare earth element is selected from at least one of TiO2, YF3, Lu2O3, LaCl3, and Y2BaZnO5, and the rare earth element includes, but is not limited to, at least one of Yb, Tm, Er, Ln, Ho, and Pr.

[0042] In some embodiments, the doping amount of rare earth elements in the material of the mononuclear upconversion particle, the material of the core of the core-shell nanostructured upconversion particle, and the material of the shell of the core-shell nanostructured upconversion particle is independently 1 to 30 mol%, for example, 1 mol%, 5 mol%, 10 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, and any range between any two of the above values.

[0043] As an example, in some embodiments, the mononuclear upconversion particles include, but are not limited to, NaErF4:Yb, NaErF4:Tm, NaErF4:(Yb,Tm), NaYF4:Er, CaF2:Er, Gd2(MoO4)3:Er, Y2O3:Er, Gd2O2S:Er, BaY2F8:Er, LiNbO3:(Er,Yb,Ln), Gd2O2:(Er,Yb), and Y3Al5O4. 12 One or more of the following: (Er,Yb), TiO2:(Er,Yb), YF3:(Er,Yb), Lu2O3:(Yb,Tm), NaYF4:(Er,Yb), LaCl3:Pr, NaYF4:(Yb,Tm), and Y2BaZnO5:(Yb,Ho).

[0044] As an example, in some embodiments, the core-shell nanostructured upconversion particles include, but are not limited to, one or more of NaYF4:(Yb,Tm)@NaYF4:Yb, NaYF4:(Yb,Tm)@NaYF4:(Yb,Nd), NaGdF4:(Yb,Tm)@NaGdF4:Ln, NaYF4:(Yb,Er)@NaYF4:(Yb,Tm), and NaYF4:(Yb,Tm)@NaGdF4:Yb.

[0045] In some embodiments, the average particle size of the upconversion particles is 10–30 nm, for example, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, and any range between any two of the stated values.

[0046] The upconversion particles described in this application have a narrow band gap and can act as a carrier transport medium within the thin film. This can effectively reduce the carrier transport barrier between quantum dots, thereby further improving the fluorescence quantum yield of the thin film and thus improving the brightness, efficiency, and lifetime of optoelectronic devices including the thin film.

[0047] The quantum dots may include, but are not limited to, one or more of the following: single-structure quantum dots, core-shell structure quantum dots, and perovskite nanocrystals. The core-shell structure quantum dots may have one or more shells.

[0048] The materials of the single-structure quantum dots, the core materials of the core-shell structure quantum dots, and the shell materials of the core-shell structure quantum dots may be, but are not limited to, one or more of the following: II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds. The group II-VI compounds may include, but are not limited to, one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe. The IV-VI group compounds may include, but are not limited to, one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe. The group III-V compounds may include, but are not limited to, one or more of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb. The group I-III-VI compounds may include, but are not limited to, one or more of CuInS2, CuInSe2, and AgInS2.

[0049] As an example, the core-shell structured quantum dots may include, but are not limited to, one or more of CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS, and InP / ZnSe / ZnS.

[0050] The perovskite nanocrystals may be made of, but are not limited to, doped or undoped inorganic perovskite semiconductors or organic-inorganic hybrid perovskite semiconductors. The inorganic perovskite semiconductor has the general structural formula AMX3, where A is Cs. + Ions, where M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2 + Yb 2+ Eu 2+ One or more of them, where X is a halide anion, including Cl. - ,Br - I - One or more of the following. The general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, where B is an organic amine cation, including CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of them, where X is a halide anion, including Cl. - ,Br - I - One or more of them.

[0051] The average particle size of the quantum dots is 5 to 30 nm, for example, 5 nm, 6 nm, 8 nm, 10 nm, 12 nm, 15 nm, 16 nm, 18 nm, 20 nm, 22 nm, 25 nm, 26 nm, 28 nm, 30 nm, and the range between any two of the stated values.

[0052] The organic ligand contains an alkyl group, and in some embodiments, the organic ligand includes, but is not limited to, substituted or unsubstituted C6-C alkyl groups. 24 Fatty acids, substituted or unsubstituted C6-C 24 Fatty amines, substituted or unsubstituted C6-C 24 Aliphatic thiols, substituted or unsubstituted C6-C 24 Aliphatic sulfides, substituted or unsubstituted C6-C 24 Aliphatic phosphine, substituted or unsubstituted C6-C 24 Aliphatic phosphine oxides, substituted or unsubstituted C8-C8 phosphine oxides 20 Aliphatic phosphates, substituted or unsubstituted C6-C 24 Aliphatic phosphates, substituted or unsubstituted C6-C 24 Aliphatic phosphorous acid and substituted or unsubstituted C6-C 24 One or more of the fatty phosphites, wherein the substituents are selected from one or more of C1-C6 alkyl, C1-C6 alkoxy and halogens.

[0053] In some embodiments, the substituted or unsubstituted C6-C 24 Fatty acids include one or more of the following: decanoic acid, undecenoic acid, tetradecanoic acid, oleic acid, linoleic acid, and stearic acid.

[0054] In some embodiments, the substituted or unsubstituted C6-C 24 Aliphatic thiols include one or more of octylthiol, dodecylthiol, and octadecylthiol.

[0055] In some embodiments, the substituted or unsubstituted C6-C 24 Fatty amines include one or more of oleylamine, octadecylamine, octylamine, dioctylamine, and trioctylamine.

[0056] In some embodiments, the substituted or unsubstituted C6-C 24 Aliphatic phosphines include trioctylphosphine.

[0057] In some embodiments, the substituted or unsubstituted C6-C 24 Aliphatic phosphine oxides include trioctylphosphine oxides.

[0058] In some embodiments, the solvent includes, but is not limited to, one or more of hydrocarbon solvents, halogenated hydrocarbon solvents, alcohol solvents, ketone solvents, ester solvents, ether solvents, pyridine solvents, amine solvents, amide solvents, and sulfone solvents. The hydrocarbon solvents include, but are not limited to, one or more of benzene, toluene, cyclohexane, and hexane; the halogenated hydrocarbon solvents include, but are not limited to, one or more of chloroform, dichloromethane, chloroform, trichloroethylene, and carbon tetrachloride; the alcohol solvents include, but are not limited to, n-butanol; the ketone solvents include, but are not limited to, one or more of acetone and methyl ethyl ketone; the ester solvents include, but are not limited to, one or more of propylene glycol methyl ether acetate, methyl formate, ethyl acetate, and dimethyl carbonate; the ether solvents include, but are not limited to, one or more of dioxane, tetrahydrofuran, diethyl ether, isopropyl ether, n-butyl ether, diphenyl ether, and dichloroethane; the pyridine solvents include, but are not limited to, pyridine; the amine solvents include, but are not limited to, one or more of acetonitrile, tetramethylethylenediamine, triethylamine, tributylamine, and trioctylamine; the amide solvents include, but are not limited to, one or more of formamide, N,N-dimethylformamide (DMF), and hexamethylphosphoramide; and the sulfone solvents include, but are not limited to, dimethyl sulfoxide (DMSO).

[0059] Secondly, embodiments of this application also provide a thin film, which is prepared from the quantum dot ink described above through a film-forming process.

[0060] The film includes a mesh framework and quantum dots and upconversion particles filled in the mesh framework. The material of the mesh framework includes crosslinked molecules, including photosensitive crosslinked molecules obtained by photocrosslinking reaction between the photocrosslinking agent described above and organic ligands on the surface of the quantum dots.

[0061] The cross-linked molecules are coordinated with the quantum dots.

[0062] In the thin film, the mass ratio of the quantum dots to the photosensitive crosslinking molecules is 1:(0.01 to 0.1), for example, 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.1, and the range between any two of the above ratios.

[0063] In some embodiments, the mass ratio of the quantum dot to the upconversion particle is 1:(0.05 to 0.2), for example, 1:0.05, 1:0.06, 1:0.08, 1:0.1, 1:0.12, 1:0.13, 1:0.15, 1:0.16, 1:0.18, 1:0.2, and the range between any two of the stated ratios.

[0064] In some embodiments, the thin film is a light-emitting thin film.

[0065] The thin film described in this application exhibits a high fluorescence quantum yield. Furthermore, the thin film includes upconversion particles, which are narrow bandgap materials and can act as carrier transport media within the film. This effectively reduces the carrier transport barrier between quantum dots, thereby further improving the fluorescence quantum yield of the thin film and consequently enhancing the brightness, efficiency, and lifetime of optoelectronic devices incorporating the thin film.

[0066] Thirdly, please refer to Figure 1 This application also provides a method for preparing a thin film, comprising the following steps:

[0067] Step S01: Provide quantum dot ink and deposit the quantum dot ink on a substrate to obtain a pre-formed film;

[0068] Step S02: Perform photolithography on the pre-formed film to obtain a thin film.

[0069] It is understood that the film described in this application may be a patterned film.

[0070] The quantum dot ink has been described above and will not be repeated here.

[0071] The substrate may be a known substrate for thin films or a substrate including a charge carrier functional layer. The substrate may be a rigid substrate or a flexible substrate. In some embodiments, the substrate material may be one or more of glass, silicon wafer, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyamide, and polyethersulfone.

[0072] In some embodiments, the method for depositing the quantum dot ink on the substrate can be a solution method, which can be spin coating, printing, inkjet printing, blade coating, dip coating, immersion coating, spraying, roller coating, casting, slot coating, and strip coating, etc.

[0073] After depositing the quantum dot ink on the substrate and before obtaining the pre-formed film, drying is also included to remove the solvent. The drying method can be a known method for drying quantum dot films, such as heat drying, reduced pressure drying, freeze drying, vacuum drying, etc.

[0074] After depositing the quantum dot ink on the substrate and before obtaining the pre-formed film, the process further includes annealing. The annealing temperature range is 80–150°C, for example, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, or any range between any two of these values. The annealing time range is 5–60 min, for example, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, or any range between any two of these values. This facilitates the preparation of a thin film with better performance.

[0075] In some embodiments, the photolithography process includes: covering the preform with a mask, then partially exposing the preform with near-infrared light, and then washing away the unexposed areas with a developer.

[0076] In some embodiments, the wavelength of the near-infrared light is 780–2526 nm, for example, 780 nm, 800 nm, 808 nm, 900 nm, 980 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1400 nm, 1500 nm, 1532 nm, 1600 nm, 1700 nm, 1800 nm, 1900 nm, 2000 nm, 2100 nm, 2200 nm, 2300 nm, 2400 nm, 2500 nm, and any range between any two of these values. The relatively long wavelength and low energy of the near-infrared light effectively reduce the direct damage to the quantum dots in the luminescent layer caused by the full coverage of the high-energy light source during photolithography, thereby effectively improving the fluorescence quantum yield of the prepared thin film.

[0077] In some embodiments, the near-infrared light illumination energy is 10–2000 mJ / cm². 2 For example, 10 mJ / cm 2 、50mJ / cm 2 100mJ / cm 2 、200mJ / cm 2 、300mJ / cm 2 、400mJ / cm 2 、500mJ / cm 2 600mJ / cm 2 700mJ / cm 2 800mJ / cm 2 900mJ / cm 2 1000mJ / cm 2 1100mJ / cm 2 1200mJ / cm 2 1300mJ / cm 2、1400mJ / cm 2 、1500mJ / cm 2 1600mJ / cm 2 1700mJ / cm 2 1800mJ / cm 2 、1900mJ / cm 2 、2000mJ / cm 2 And the range between any two values, etc.

[0078] During the exposure process, upconversion particles in the exposed area of ​​the preform absorb the near-infrared light and convert the absorbed near-infrared light into short-wavelength light, which can be blue light or ultraviolet light. The blue light or ultraviolet light can promote the crosslinking reaction between the photocrosslinking agent and the organic ligands on the surface of the quantum dots to form crosslinked molecules.

[0079] In some embodiments, the wavelength of the short-wavelength light is 200–500 nm, for example, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, and any range between any two of the above values.

[0080] Understandably, the developer is a solvent capable of dissolving the quantum dots, upconversion particles, and photocrosslinking agent. In some embodiments, the developer includes, but is not limited to, one or more of hydrocarbon solvents, halogenated hydrocarbon solvents, alcohol solvents, ketone solvents, ester solvents, ether solvents, pyridine solvents, amine solvents, amide solvents, and sulfone solvents. The hydrocarbon solvents include, but are not limited to, one or more of benzene, toluene, cyclohexane, and hexane; the halogenated hydrocarbon solvents include, but are not limited to, one or more of chloroform, dichloromethane, chloroform, trichloroethylene, and carbon tetrachloride; the alcohol solvents include, but are not limited to, n-butanol; the ketone solvents include, but are not limited to, one or more of acetone and methyl ethyl ketone; the ester solvents include, but are not limited to, one or more of propylene glycol methyl ether acetate, methyl formate, ethyl acetate, and dimethyl carbonate; the ether solvents include, but are not limited to, one or more of dioxane, tetrahydrofuran, diethyl ether, isopropyl ether, n-butyl ether, diphenyl ether, and dichloroethane; the pyridine solvents include, but are not limited to, pyridine; the amine solvents include, but are not limited to, one or more of acetonitrile, tetramethylethylenediamine, triethylamine, tributylamine, and trioctylamine; the amide solvents include, but are not limited to, one or more of formamide, N,N-dimethylformamide (DMF), and hexamethylphosphoramide; and the sulfone solvents include, but are not limited to, dimethyl sulfoxide (DMSO).

[0081] The thin film preparation method described in this application uses the quantum dot ink described above. This allows for the use of low-energy near-infrared light (long-wavelength light) for exposure during photolithography, effectively avoiding direct damage to the quantum dots in the emitting layer from the full coverage of high-energy light sources. This results in almost no attenuation of the fluorescence performance of the thin film prepared by photolithography, leading to a high fluorescence quantum yield, which is significant for the application of high-resolution photolithography QLED technology. Furthermore, the thin film prepared using the quantum dot ink described in this application includes the upconversion particles, which are narrow bandgap materials and can act as carrier transport media within the film. This effectively reduces the carrier transport barrier between quantum dots, further improving the fluorescence quantum yield of the film, and consequently enhancing the brightness, efficiency, and lifetime of optoelectronic devices containing the film.

[0082] It should be noted that during the photolithography process, cross-linking reactions may occur between photocrosslinking agents to generate photocrosslinking agent crosslinking molecules, and cross-linking reactions may also occur between organic ligands on the quantum dot surface to generate organic ligand crosslinking molecules. Thus, the crosslinking molecules in the prepared film may also include the photocrosslinking agent crosslinking molecules and / or the organic ligand crosslinking molecules.

[0083] Fourthly, please refer to Figure 2 This application also provides an optoelectronic device 100, comprising an anode 10, a light-emitting layer 20, and a cathode 30 stacked sequentially. The light-emitting layer 20 comprises the thin film described above, or the light-emitting layer 20 is prepared by the thin film preparation method described above.

[0084] In some embodiments, the optoelectronic device 100 further includes an electron transport layer 40, which is located between the light-emitting layer 20 and the cathode 30.

[0085] In some embodiments, the optoelectronic device 100 further includes a hole transport layer 50, which is located between the light-emitting layer 20 and the anode 10.

[0086] In some embodiments, the optoelectronic device 100 further includes a hole injection layer 60, which is located between the light-emitting layer 20 and the hole transport layer 50.

[0087] The anode and cathode are anodes and cathodes known in the art for use in optoelectronic devices, and may be independently selected from, but not limited to, doped metal oxide electrodes, composite electrodes, graphene electrodes, carbon nanotube electrodes, elemental metal electrodes, or alloy electrodes. The material of the doped metal oxide electrode may be selected from, but not limited to, at least one of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), magnesium-doped zinc oxide (MZO), and aluminum-doped magnesium oxide (AMO). The composite electrode is a composite electrode in which a metal is sandwiched between doped or undoped transparent metal oxides, such as AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, ZnS / Al / ZnS, etc. The material of the elemental metal electrode can be selected from, but is not limited to, at least one of Ag, Al, M, Au, Pt, Ca, and Ba. Here, " / " indicates a stacked structure; for example, AZO / Ag / AZO represents a composite electrode comprising sequentially stacked AZO, Ag, and AZO layers.

[0088] The material of the electron transport layer 40 includes, but is not limited to, one or more of N-type inorganic particles and N-type organic materials. The materials of the N-type inorganic particles include, but are not limited to, one or more of the following: first doped metal oxide particles, first undoped metal oxide particles, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the first undoped metal oxide particles include, but are not limited to, one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5. The metal oxides in the first doped metal oxide particles include, but are not limited to, one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, and Al2O3. The doping elements in the first doped metal oxide particles include, but are not limited to, one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, and Ga. The IIB-VIA group semiconductor materials include, but are not limited to, one or more of ZnS, ZnSe, and CdS. The IIIA-VA group semiconductor materials include, but are not limited to, one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include, but are not limited to, one or more of CuInS and CuGaS.The N-type organic materials include, but are not limited to, diphenyl[4-(triphenylsilyl)phenyl]phosphine oxide (TSPO1), 1,3,5-tris((3-pyridyl)-3-phenyl)benzene (TmPyPB), 2-(4-biphenyl)-5-phenyloxadiazole (PBD), bis(10-hydroxybenzo[h]quinoline)beryllium (Bebq2) (CAS: 148896-39-3), and 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole (…). TAZ), 2,7-bis(diphenylphosphino)-9,9'-spirobis[fluorene](SPPO13), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)phenyl (TPBI), 4,6-bis(3,5-di(3-pyridinylphenyl)-2-methylpyrimidine (B3PYMPM), 4,7-diphenyl-1,10-phenanthroline (BPhen), 2-(4'-tert-butylphenyl)-5-(4'-biphenyl)-1,3,4-oxadiazole, 2,9-dimethyl-4, 7-Diphenyl-1,10-o-phenanthroline, 4,7-Diphenyl-1,10-o-phenanthroline, bis(2-methyl-8-hydroxyquinoline-N1,O8)-1,1'-biphenyl-4-hydroxy)aluminum, 8-hydroxyquinoline aluminum (Alq3), 2,7-bis(diphenyloxyphosphino)-9,9'-spirobis[fluorene], poly[9,9-dioctylfluorene-9,9-bis(N,N-dimethylaminopropyl)fluorene], 9,9-bis[3'-(N,N-dimethylamino)propyl-2,7-fluorene]-alternating-2 One or more of the following: 7-(9,9-dioctylfluorene), 1,3-bis[5-(4-tert-butylphenyl)-2-[1,3,4]oxadiazolyl]benzene (OXD-7), 3',3'",3'""-(1,3,5-triazine-2,4,6-triyl)-tris(([1,1'-biphenyl]-3-carboxynitrile))(CNT2T), and 2,4,6-tris[3-(diphenylphosphoxy)phenyl]-1,3,5-triazole (POT2T, CAS No.: 1646906-26-4).

[0089] The materials of the hole transport layer 50 and the hole injection layer 60 each independently include, but are not limited to, one or more of P-type inorganic particles and P-type organic materials. The P-type inorganic particles include, but are not limited to, one or more of second-doped metal oxide particles, second-undoped metal oxide particles, metal sulfides, metal selenides, and metal nitrides. The metal oxides in the second-doped metal oxide particles and the metal oxides in the second-undoped metal oxide particles each independently include, but are not limited to, one or more of MoO3, WO3, NiO, CrO3, CuO, Cu2O, V2O5. The doping elements in the second-doped metal oxide particles include, but are not limited to, one or more of Mo, W, Ni, Cr, Cu, V. The metal sulfides include, but are not limited to, one or more of CuS, MoS3, WS3. The metal selenides include, but are not limited to, one or more of MoSe3, WSe3. The metal nitrides include, but are not limited to, P-type gallium nitride. The P-type organic semiconductor material may be selected from, but is not limited to, 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine (α-NPD), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD), poly(N,N' bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (Poly-TPD), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro(spiro-TPD), N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine (DNTPD), 4,4',4'-tris(N-carbazolyl)-triphenylamine (TCTA), 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))] (TFB), poly(N-vinylcarbazole) (PVK) and its derivatives, N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine (NPB), spiro-NPB, poly(phenylenevinylene) (PPV), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MOMO-PPV), 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (spiro-omeTAD), 4,4'-cyclohexylbis[N,[N-Di(4-methylphenyl)aniline] (TAPC), 1,3-Di(carbazole-9-yl)phenyl (MCP), polyaniline, polypyrrole, poly(p-)phenylenevinylene, aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazole)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylates and their derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, 2,3,6,7, One or more of the following: 10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (HAT-CN), PEDOT, PEDOT:PSS, PEDOT:PSS-doped s-MoO3 derivatives (PEDOT:PSS:s-MoO3), 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), tetracyanoquinone dimethylane (F4-TCQN), doped graphene, undoped graphene, C60, and copper phthalocyanine.

[0090] It is understood that the optoelectronic device 100 may also be provided with some functional layers that help improve the performance of the optoelectronic device, such as an electron injection layer, an electron blocking layer, a hole blocking layer, an interface modification layer, etc.

[0091] It is understood that the materials of each layer of the optoelectronic device 100 can be adjusted according to the light emission requirements of the optoelectronic device 100.

[0092] It is understood that the optoelectronic device 100 can be an upright optoelectronic device or an inverted optoelectronic device.

[0093] In some embodiments, the optoelectronic device 100 further includes a substrate located on the surface of the anode 10 away from the light-emitting layer 20, or the substrate located on the surface of the cathode 30 away from the light-emitting layer 20.

[0094] The substrate can be a rigid substrate or a flexible substrate. In some embodiments, the substrate material may include, but is not limited to, one or more of glass, silicon wafer, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyamide, and polyethersulfone.

[0095] It is understood that the optoelectronic device 100 can be an upright optoelectronic device or an inverted optoelectronic device. The optoelectronic device 100 can be a quantum dot optoelectronic device or an organic optoelectronic device.

[0096] Fifthly, this application also relates to a display device, which includes the optoelectronic device 100.

[0097] The display device can be any electronic product with display function, including but not limited to smartphones, tablets, laptops, digital cameras, digital camcorders, smart wearable devices, smart weighing scales, in-vehicle displays, televisions, or e-book readers. Among them, smart wearable devices can be, for example, smart bracelets, smartwatches, virtual reality (VR) headsets, etc.

[0098] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0099] Thin Film Example 1

[0100] Step 1: Provide quantum dot ink, which comprises red quantum dots (average particle size), upconversion particles, a photocrosslinking agent, and an alkane solvent. The red quantum dots are CdZnSe / CdZnS / ZnS (average particle size 16 nm), the upconversion particles are NaYF:Yb,Tm (average particle size 20 nm), the photocrosslinking agent is ethane-1,2-dimethylbis(4-azido-2,3,5,6-tetrafluorobenzoate), and the solvent is n-octane. The concentration range of the quantum dots is 30 mg / ml, the mass ratio of quantum dots to the photocrosslinking agent is 1:0.05, and the mass ratio of quantum dots to the upconversion particles is 1:0.1.

[0101] Step 2: Spin-coat the quantum dot ink onto the substrate, and then anneal it on a hot plate at 120°C for 10 minutes to obtain a pre-formed film with a thickness of 30 nm.

[0102] Step 3, Photolithography: A photomask is placed on the upper surface of the pre-formed film, and then photolithography is performed using a wavelength of 808 nm and an illumination energy of 60 mJ / cm². 2 The preform is exposed by near-infrared light through the mask to expose the area of ​​the preform. The mask is then removed, and the unexposed areas are washed with toluene (developer) to obtain a patterned film with a thickness of 30 nm.

[0103] Thin Film Example 2

[0104] This embodiment is basically the same as thin film embodiment 1, except that the wavelength of the near-infrared light in this embodiment is 980nm and the light energy is 50mJ / cm. 2 .

[0105] Thin Film Example 3

[0106] This embodiment is basically the same as thin film embodiment 1, except that the wavelength of the near-infrared light in this embodiment is 1532nm and the light energy is 80mJ / cm². 2 .

[0107] Thin Film Example 4

[0108] This embodiment is basically the same as thin film embodiment 1, except that the mass ratio of quantum dots to photocrosslinking agent in this embodiment is 1:0.01.

[0109] Thin Film Example 5

[0110] This embodiment is basically the same as thin film embodiment 1, except that the mass ratio of quantum dots to photocrosslinking agent in this embodiment is 1:0.1.

[0111] Thin Film Example 6

[0112] This embodiment is basically the same as thin film embodiment 1, except that the mass ratio of quantum dots to upconversion particles in this embodiment is 1:0.05.

[0113] Thin Film Example 7

[0114] This embodiment is basically the same as thin film embodiment 1, except that the mass ratio of quantum dots to upconversion particles is 1:0.2 in this embodiment.

[0115] Thin Film Example 8

[0116] This embodiment is basically the same as Thin Film Embodiment 1, except that in this embodiment, upconversion particles NaErF4:Yb are used to replace the upconversion particles in Thin Film Embodiment 1.

[0117] Thin Film Example 9

[0118] This embodiment is basically the same as Thin Film Embodiment 1, except that in this embodiment, upconversion particles NaYF4:Er are used to replace the upconversion particles in Thin Film Embodiment 1.

[0119] Thin Film Example 10

[0120] This embodiment is basically the same as Thin Film Embodiment 1, except that in this embodiment, upconversion particles NaYF4:(Yb,Er)@NaYF4:(Yb,Tm) are used to replace the upconversion particles in Thin Film Embodiment 1.

[0121] Thin Film Example 11

[0122] This embodiment is basically the same as Thin Film Embodiment 1, except that in this embodiment, upconversion particles NaYF4:(Yb,Tm)@NaYF4:(Yb,Nd) are used to replace the upconversion particles in Thin Film Embodiment 1.

[0123] Thin Film Example 12

[0124] This embodiment is basically the same as film embodiment 1, except that the photocrosslinking agent 4-(P-azidosalicylic acid amino)-butylamine is used to replace the photocrosslinking agent in film embodiment 1.

[0125] Thin Film Example 13

[0126] This embodiment is basically the same as film embodiment 1, except that the photocrosslinking agent azide-tetraethylene glycol-amino is used in this embodiment to replace the photocrosslinking agent in film embodiment 1.

[0127] Thin Film Example 14

[0128] This embodiment is basically the same as film embodiment 1, except that the photocrosslinking agent triphenylphosphine is used in this embodiment to replace the photocrosslinking agent in film embodiment 1.

[0129] Thin Film Example 15

[0130] This embodiment is basically the same as Thin Film Embodiment 1, except that green quantum dots CdZnSe / ZnSe / CdZnS are used to replace the quantum dots in Thin Film Embodiment 1.

[0131] Thin Film Example 16

[0132] This embodiment is basically the same as Thin Film Embodiment 1, except that blue quantum dots CdZnSe / ZnSe / ZnS are used to replace the quantum dots in Thin Film Embodiment 1.

[0133] Thin Film Comparative Example 1

[0134] This comparative example is basically the same as that of thin film example 1, except that it does not include a photocrosslinking agent.

[0135] Thin Film Comparative Example 2

[0136] This comparative example is basically the same as that of thin film example 1, except that it does not include upconversion particles.

[0137] Thin Film Comparative Example 3

[0138] This comparative example is basically the same as that of Thin Film Example 1, except that this comparative example uses a wavelength of 405nm and a light energy of 55mJ / cm. 2 The ultraviolet light replaces the near-infrared light in Example 1 of the thin film.

[0139] Thin film comparative example 4

[0140] This comparative example is basically the same as that of thin film example 15, except that this comparative example uses a wavelength of 365nm and a light energy of 60mJ / cm. 2 The ultraviolet light replaces the near-infrared light in Example 1 of the thin film.

[0141] Thin film comparative example 5

[0142] This comparative example is basically the same as that of thin film example 16, except that this comparative example uses a wavelength of 245nm and a light energy of 45mJ / cm. 2 The ultraviolet light replaces the near-infrared light in Example 1 of the thin film.

[0143] Fluorescence quantum yield tests were performed on the pre-lithographic and post-lithographic films of Thin Film Examples 1-16 and Comparative Examples 1-5. The test results are shown in Table 1.

[0144] Fluorescence quantum yield (PLQY) was measured using a steady-state fluorescence spectrometer from Edinburgh Instruments, model FS5, with the corresponding accessory SC-30 for measuring fluorescence quantum yield.

[0145] Table 1:

[0146]

[0147] As shown in Table 1:

[0148] The films in Comparative Examples 1-5 showed a significant decrease in fluorescence quantum yield after photolithography, while the films in Examples 1-16 still exhibited high fluorescence quantum yield after photolithography. It is evident that the thin film prepared using the quantum dot ink described in this application exhibits a high fluorescence quantum yield. This may be because the upconversion particles in the quantum dot ink can absorb low-energy light (long-wavelength light) and convert it into high-energy light (short-wavelength light) suitable for photolithographic quantum dot thin films. During this process, the light converted by the upconversion particles within the quantum dot thin film induces a crosslinking reaction between the photocrosslinking agent and the organic ligands on the quantum dot surface. Thus, when preparing patterned thin films using the quantum dot ink, long-wavelength, low-energy near-infrared light can be used for photolithography, effectively avoiding direct damage to the luminescent quantum dots from the full coverage of the high-energy light source, thereby effectively improving the fluorescence quantum yield of the thin film. Furthermore, the thin film prepared using the quantum dot ink contains the upconversion particles, which are narrow-bandgap materials and can act as carrier transport media within the thin film. This effectively reduces the carrier transport barrier between quantum dots, further improving the fluorescence quantum yield of the thin film.

[0149] Device Example 1

[0150] Step S1: Provide an ITO anode substrate;

[0151] Step S2: Spin-coat PEDOT:PSS material onto the anode, then heat at 100°C for 15 minutes to obtain a hole injection layer with a thickness of 40 nm;

[0152] Step S3: Spin-coat TFB material (8 mg / mL) onto the hole injection layer, then heat at 80°C for 10 minutes to obtain a hole transport layer with a thickness of 30 nm;

[0153] Step S4: A thin film is prepared on the hole transport layer using the preparation method of Thin Film Example 1 to obtain a light-emitting layer with a thickness of 20 nm;

[0154] Step S5: Spin-coat an ethanol solution of ZnO (30 mg / mL) onto the light-emitting layer, and then heat at 120°C for 15 minutes to obtain an electron transport layer with a thickness of 40 nm.

[0155] Step S6: Through thermal evaporation, the vacuum level is not higher than 3×10. -4 Pa, Ag is deposited on the electron transport layer at a deposition rate of 0.8 Å / s to obtain a cathode with a thickness of 100 nm;

[0156] Step S7: Encapsulate with epoxy resin to obtain the optoelectronic device.

[0157] Device Examples 2-16

[0158] The preparation methods of the optoelectronic devices in Device Examples 2 to 16 are the same as those in Device Example 1, except that the light-emitting layers of the optoelectronic devices in Device Examples 2 to 16 are prepared using the same thin film preparation methods as those in Thin Film Examples 2 to 16.

[0159] Device Comparison Examples 1-5

[0160] The optoelectronic devices of Comparative Examples 1 to 5 were prepared using the same methods as those in Device Example 1. The light-emitting layers of the optoelectronic devices of Comparative Examples 1 to 5 were prepared using the same methods as those used in Comparative Examples 1 to 5.

[0161] The external quantum efficiency (EQE) and lifetime (T95@1000nit) of the optoelectronic devices in Device Examples 1-16 and Device Comparative Examples 1-5 were tested respectively. The test results are shown in Table 2.

[0162] External quantum efficiency (EQE) is the ratio of electron-hole pairs injected into a quantum dot to emitted photons, expressed as a percentage (%). It is an important parameter for evaluating the quality of electroluminescent optoelectronic devices and can be measured using EQE optical testing instruments. The specific calculation formula is as follows:

[0163]

[0164] Where ηe is the optical output coupling efficiency, ηr is the ratio of the number of recombinated carriers to the number of injected carriers, χ is the ratio of the number of excitons that generate photons to the total number of excitons, KR is the radiative process rate, and KNR is the non-radiative process rate.

[0165] The lifetime test method T95@1000nit is as follows: In CDA gas, under constant current drive, the time it takes for the device brightness to decay to a certain percentage of its maximum brightness is measured. The time for the brightness to decay to 95% of the maximum brightness is defined as T95, and this lifetime is the measured lifetime. To shorten the lifetime testing cycle, device lifetime testing is usually performed at high brightness by accelerating device aging, and the lifetime at low brightness is obtained by fitting the decay fitting formula. For example, the lifetime at 1000 nits is denoted as T95@1000nits, and the calculation formula is as follows:

[0166]

[0167] Among them, T95 L The lifespan at low brightness is typically taken as the lifespan at 1000 nits, T95. H The lifetime at high brightness, i.e., the measured lifetime, L H L is the maximum brightness that the device accelerates to. L The typical value is 1000 nits, where A is the acceleration factor, taken as 1.7. The constant current is 2 mA.

[0168] The above test conditions were: conducted at room temperature with an air humidity of 50%.

[0169] Table 2:

[0170]

[0171]

[0172] As shown in Table 2:

[0173] Compared to the optoelectronic devices in Comparative Examples 1-3, the optoelectronic devices in Examples 1-14 exhibit higher external quantum efficiency and longer lifetime; compared to the optoelectronic device in Comparative Example 4, the optoelectronic device in Example 15 exhibits higher external quantum efficiency and longer lifetime; and compared to the optoelectronic device in Comparative Example 5, the optoelectronic device in Example 16 exhibits higher external quantum efficiency and longer lifetime. It is evident that using the quantum dot ink described in this application to prepare the light-emitting layer of the optoelectronic device can effectively improve the efficiency and lifetime of the optoelectronic device. This is likely because the thin film prepared using the quantum dot ink described in this application has a high fluorescence quantum yield.

[0174] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A quantum dot ink, characterized in that, This includes quantum dots, upconversion particles, photocrosslinking agents, and solvents.

2. The quantum dot ink as described in claim 1, characterized in that, The mass ratio of the quantum dots to the photocrosslinking agent is 1:(0.01~0.1); And / or, the mass ratio of the quantum dot to the upconversion particle is 1:(0.05~0.2); And / or, in the quantum dot ink, the concentration of the quantum dots ranges from 10 to 100 mg / mL.

3. The quantum dot ink as described in claim 1, characterized in that, The photocrosslinking agent includes one or more of the following: azide compound photocrosslinking agents, organophosphorus photocrosslinking agents, diazonium pyrazine, and triphenylmethyl chloride; And / or, the upconversion particles include one or more of mononuclear upconversion particles and core-shell nanostructured upconversion particles; And / or, the quantum dots include one or more of the following: single-structure quantum dots, core-shell structure quantum dots, and perovskite nanocrystals.

4. The quantum dot ink as described in claim 3, characterized in that, The average particle size of the quantum dots is 5–30 nm; And / or, the average particle size of the upconversion particles is 10–30 nm; And / or, the organophosphorus photocrosslinking agent includes one or more of diphenylphosphine, triphenylphosphine, and tris(dipyridyl)phosphine; And / or, the azide compound photocrosslinker includes one or more of aryl azide compound photocrosslinkers and alkyl azide compound photocrosslinkers, wherein the aryl azide compound photocrosslinker includes, but is not limited to, ethane-1,2-dimethylbis(4-azido-2,3,5,6-tetrafluorobenzoate), 6-[(4-azido-2-nitrophenyl)amino]hexanoic acid sulfonate succinimide, sodium 4,4'-diazidostyrene-2,2'-disulfonate, 4-azidobenzaldehyde, 2,6-bis(4-azidobenzaldehyde), etc. One or more of (-azidobenzyl)-4-methylcyclohexanone and 4-(P-azidosalicylic acid)-butylamine, wherein the alkyl azido compound photocrosslinking agent includes one or more of azido-tetraethylene glycol-amino, 3-(2-azidoethyl)-3-methyl-3H-diazine, 3-azido-1-propanol, 3,3-bis(azidomethyl)thiocyclobutane 1,1-dioxide, 1,5-bisazido-3-oxapentane, and 1,11-diazido-3,6,9-trioxaundecanane; And / or, the material of the mononuclear upconversion particle, the material of the core of the core-shell nanostructured upconversion particle, and the material of the shell of the core-shell nanostructured upconversion particle each independently include rare earth elements doped with NaYbF4, NaLuF4, NaGaF4, NaErF4, NaYF4, CaF2, Gd2(MoO4)3, Y2O3, Gd2O2S, BaY2F8, LiNbO3, Gd2O2, Y3Al5O 12 The rare earth element is selected from at least one of TiO2, YF3, Lu2O3, LaCl3, and Y2BaZnO5, and the rare earth element includes at least one of Yb, Tm, Er, Ln, Ho, and Pr. Optionally, the doping amount of the rare earth element in the material of the mononuclear upconversion particle, the material of the core of the core-shell nanostructured upconversion particle, and the material of the shell of the core-shell nanostructured upconversion particle is independently 1 to 30 mol%. And / or, the mononuclear upconversion particles include NaErF4:Yb, NaErF4:Tm, NaErF4:(Yb,Tm), NaYF4:Er, CaF2:Er, Gd2(MoO4)3:Er, Y2O3:Er, Gd2O2S:Er, BaY2F8:Er, LiNbO3:(Er,Yb,Ln), Gd2O2:(Er,Yb), Y3Al5O 12 One or more of the following: (Er,Yb), TiO2:(Er,Yb), YF3:(Er,Yb), Lu2O3:(Yb,Tm), NaYF4:(Er,Yb), LaCl3:Pr, NaYF4:(Yb,Tm), and Y2BaZnO5:(Yb,Ho); And / or, the core-shell nanostructured upconversion particles include one or more of NaYF4:(Yb,Tm)@NaYF4:Yb, NaYF4:(Yb,Tm)@NaYF4:(Yb,Nd), NaGdF4:(Yb,Tm)@NaGdF4:Ln, NaYF4:(Yb,Er)@NaYF4:(Yb,Tm), and NaYF4:(Yb,Tm)@NaGdF4:Yb; And / or, the material of the single-structure quantum dot, the core material of the core-shell structure quantum dot, and the shell material of the core-shell structure quantum dot are each independently selected from one or more of group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I-III-VI compounds, wherein the group II-VI compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, and Hg One or more of the following compounds: SeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe, wherein the group IV-VI compounds include SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, and Sn SeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, and SnPb, wherein the III-V compound comprises one or more of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, and A. One or more of lPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb, wherein the group I-III-VI compounds include one or more of CuInS2, CuInSe2, and AgInS2; And / or, the perovskite nanocrystal material comprises a doped or undoped inorganic perovskite semiconductor or an organic-inorganic hybrid perovskite semiconductor, wherein the general structural formula of the inorganic perovskite semiconductor is AMX3, where A is Cs. + Ions, where M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of them, where X is a halide anion, including Cl. - ,Br - I - One or more of the following; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, where B is an organic amine cation, including CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2 + Eu 2+ One or more of them, where X is a halide anion, including Cl. - ,Br - I - One or more of the following; And / or, the quantum dots are surface-coordinated with organic ligands, the organic ligands containing alkyl groups, the organic ligands comprising substituted or unsubstituted C6-C groups. 24 Fatty acids, substituted or unsubstituted C6-C 24 Fatty amines, substituted or unsubstituted C6-C 24 Aliphatic thiols, substituted or unsubstituted C6-C 24 Aliphatic sulfides, substituted or unsubstituted C6-C 24 Aliphatic phosphine, substituted or unsubstituted C6-C 24 Aliphatic phosphine oxides, substituted or unsubstituted C8-C8 phosphine oxides 20 Aliphatic phosphates, substituted or unsubstituted C6-C 24 Aliphatic phosphates, substituted or unsubstituted C6-C 24 Aliphatic phosphorous acid and substituted or unsubstituted C6-C 24 One or more of the fatty phosphites, wherein the substituent is selected from one or more of C1-C6 alkyl, C1-C6 alkoxy, and halogen, and the substituted or unsubstituted C6-C... 24 Fatty acids include one or more of decanoic acid, undecenoic acid, tetradecanoic acid, oleic acid, linoleic acid, and stearic acid, wherein the substituted or unsubstituted C6-C... 24 Aliphatic thiols include one or more of octylthiol, dodecylthiol, and octadecylthiol, wherein the substituted or unsubstituted C6-C 24 Fatty amines include one or more of oleylamine, octadecylamine, octylamine, dioctylamine, and trioctylamine, wherein the substituted or unsubstituted C6-C... 24 Aliphatic phosphines include trioctylphosphine, the substituted or unsubstituted C6-C 24 Aliphatic phosphine oxides include trioctylphosphine oxide; And / or, the solvent includes one or more of hydrocarbon solvents, halogenated hydrocarbon solvents, alcohol solvents, ketone solvents, ester solvents, ether solvents, pyridine solvents, amine solvents, amide solvents, and sulfone solvents; the alcohol solvent includes n-butanol; the pyridine solvent includes pyridine; the sulfone solvent includes dimethyl sulfoxide; the ketone solvent includes one or more of acetone and methyl ethyl ketone; the hydrocarbon solvent includes one or more of benzene, toluene, cyclohexane, and hexane; and the halogenated hydrocarbon solvent includes chloroform, dichloromethane, and chlorine. The solvent comprises one or more of the following: methyl methacrylate, trichloroethylene, and carbon tetrachloride; the ester solvent comprises one or more of the following: propylene glycol methyl ether acetate, methyl formate, ethyl acetate, and dimethyl carbonate; the ether solvent comprises one or more of the following: dioxane, tetrahydrofuran, diethyl ether, isopropyl ether, n-butyl ether, diphenyl ether, and dichloroethane; the amine solvent comprises one or more of the following: acetonitrile, tetramethylethylenediamine, triethylamine, tributylamine, and trioctylamine; and the amide solvent comprises one or more of the following: formamide, N,N-dimethylformamide, and hexamethylphosphoramide.

5. A thin film, characterized in that, It includes a mesh framework and quantum dots and upconversion particles filled in the mesh framework, wherein the material of the mesh framework includes cross-linked molecules.

6. The thin film as described in claim 5, characterized in that, The cross-linked molecules are coordinated and connected to the quantum dots; And / or, the crosslinking molecule includes a photosensitive crosslinking molecule obtained by photocrosslinking an agent with an organic ligand on the surface of a quantum dot through a photocrosslinking reaction; optionally, the mass ratio of the quantum dot to the photosensitive crosslinking molecule is 1:(0.01 to 0.1); And / or, the mass ratio of the quantum dot to the upconversion particle is 1:(0.05 to 0.2).

7. A method for preparing a thin film, characterized in that, Includes the following steps: Provide the quantum dot ink according to any one of claims 1 to 4, and deposit the quantum dot ink on a substrate to obtain a preform film; The pre-fabricated film is subjected to photolithography to obtain a thin film.

8. The preparation method according to claim 7, characterized in that, The process, which involves depositing the quantum dot ink onto a substrate and before obtaining the preform, includes annealing. And / or, the photolithography process includes: covering the preform with a mask, then partially exposing the preform with near-infrared light, and then washing away the unexposed areas with a developer.

9. The preparation method according to claim 8, characterized in that, The annealing temperature range is 80–150°C; And / or, the annealing time ranges from 5 to 60 minutes; And / or, the wavelength of the near-infrared light is 780–2526 nm; And / or, the illumination energy of the near-infrared light is 10–2000 mJ / cm². 2 ; And / or, the developer comprises one or more of the following: hydrocarbon solvents, halogenated hydrocarbon solvents, alcohol solvents, ketone solvents, ester solvents, ether solvents, pyridine solvents, amine solvents, amide solvents, and sulfone solvents; the alcohol solvent comprises n-butanol; the pyridine solvent comprises pyridine; the sulfone solvent comprises dimethyl sulfoxide; the ketone solvent comprises one or more of acetone and methyl ethyl ketone; the hydrocarbon solvent comprises one or more of benzene, toluene, cyclohexane, and hexane; and the halogenated hydrocarbon solvent comprises chloroform, dichloromethane, and chloroform. The solvent comprises one or more of the following: methyl methacrylate, trichloroethylene, and carbon tetrachloride; the ester solvent comprises one or more of the following: propylene glycol methyl ether acetate, methyl formate, ethyl acetate, and dimethyl carbonate; the ether solvent comprises one or more of the following: dioxane, tetrahydrofuran, diethyl ether, isopropyl ether, n-butyl ether, diphenyl ether, and dichloroethane; the amine solvent comprises one or more of the following: acetonitrile, tetramethylethylenediamine, triethylamine, tributylamine, and trioctylamine; and the amide solvent comprises one or more of the following: formamide, N,N-dimethylformamide, and hexamethylphosphoramide.

10. A photoelectric device, comprising a stacked anode, a light-emitting layer, and a cathode, characterized in that, The light-emitting layer is the thin film according to any one of claims 5 to 6, or the light-emitting layer is a thin film prepared by the preparation method according to any one of claims 7 to 9.

11. The optoelectronic device as described in claim 10, characterized in that, The anode and the cathode are each independently selected from doped metal oxide electrodes, composite electrodes, graphene electrodes, carbon nanotube electrodes, elemental metal electrodes, or alloy electrodes. The material of the doped metal oxide electrode is selected from at least one of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The composite electrode is selected from AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, or ZnS / Al / ZnS. The material of the elemental metal electrode is selected from at least one of Ag, Al, Mg, Au, Pt, Ca, and Ba. And / or, the optoelectronic device further includes an electron transport layer located between the cathode and the light-emitting layer, the electron transport layer being made of one or more of N-type inorganic particles and N-type organic materials, the N-type inorganic particles being made of one or more of a first doped metal oxide particle, a first undoped metal oxide particle, a group IIB-VIA semiconductor material, a group IIIA-VA semiconductor material, and a group IB-IIIA-VIA semiconductor material, the first undoped metal oxide particle being made of one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5, the first do ... ZnO2, ZrO2, The metal oxide in the particles includes one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, and Al2O3; the doping element in the first doped metal oxide particles includes one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, and Ga; the IIB-VIA group semiconductor material includes one or more of ZnS, ZnSe, and CdS; the IIIA-VA group semiconductor material includes one or more of InP and GaP; and the IB-IIIA-VIA group semiconductor material includes one or more of CuInS and CuGaS.The N-type organic materials include diphenyl[4-(triphenylsilyl)phenyl]phosphine oxide, 1,3,5-tris((3-pyridyl)-3-phenyl)benzene, 2-(4-biphenyl)-5-phenyloxadiazole, bis(10-hydroxybenzo[h]quinoline)beryllium, 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole, and 2,7-bis(diphenylphosphine oxide)-9, 9'-spirobis[fluorene], 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, 4,6-bis(3,5-di(3-pyridinylphenyl)-2-methylpyrimidine 4,7-diphenyl-1,10-phenanthroline, 2-(4'-tert-butylphenyl)-5-(4'-biphenyl)-1,3,4-oxadiazole, 2,9-dimethyl-4,7-diphenyl-1,10-o-diazaphenanthroline, 4,7 -Diphenyl-1,10-o-phenanthroline, bis(2-methyl-8-hydroxyquinoline-N1,O8)-1,1'-biphenyl-4-hydroxy)aluminum, 8-hydroxyquinolinealuminum, 2,7-bis(diphenylphosphine oxide)-9,9'-spirobis[fluorene], poly[9,9-dioctylfluorene-9,9-bis(N,N-dimethylaminopropyl)fluorene], 9,9-bis[3'-(N,N-dimethylamino)propyl-2,7-fluorene] One or more of the following: ]-alternating-2,7-(9,9-dioctylfluorene), 1,3-bis[5-(4-tert-butylphenyl)-2-[1,3,4]oxadiazolyl]benzene, 3',3'",3'""-(1,3,5-triazine-2,4,6-triyl)-tris(([1,1'-biphenyl]-3-carboxynitrile)), and 2,4,6-tris[3-(diphenylphosphoxy)phenyl]-1,3,5-triazole; And / or, the optoelectronic device further includes a hole transport layer and a hole injection layer located between the anode and the light-emitting layer. The materials of the hole transport layer and the hole injection layer each independently include one or more of P-type inorganic particles and P-type organic materials. The P-type inorganic particles include one or more of second-doped metal oxide particles, second-undoped metal oxide particles, metal sulfides, metal selenides, and metal nitrides. The metal oxides in the second-doped metal oxide particles and the metal oxides in the second-undoped metal oxide particles each independently include one or more of MoO3, WO3, NiO, CrO3, CuO, Cu2O, and V2O5. The doping elements in the oxide particles include one or more of Mo, W, Ni, Cr, Cu, and V; the metal sulfide includes one or more of CuS, MoS3, and WS3; the metal selenide includes one or more of MoSe3 and WSe3; the metal nitride includes p-type gallium nitride; and the p-type organic semiconductor material includes 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, and N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine. Poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(N-vinylcarbazole) (PVK) and its derivatives, N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1' -Biphenyl-4-4'-diamine, spiroNPB, poly(phenylenevinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene], 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene, 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline], 1,3-di(carbazole-9-yl)benzene, polyaniline, polypyrrole, poly(p)phenylenevinylene, aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazole)-1,1'-biphenyl compounds, N,N,N',The following are selected from the following: N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene, PEDOT, PEDOT:PSS, PEDOT:PSS derivatives doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinone dimethane, doped graphene, undoped graphene, C60, and copper phthalocyanine.

12. A display device, characterized in that, Includes the optoelectronic device according to any one of claims 10 to 11.

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