CN113045934A

CN113045934A - Printing ink, application thereof and preparation method of quantum dot film

Info

Publication number: CN113045934A
Application number: CN201911383355.2A
Authority: CN
Inventors: 李雪
Original assignee: TCL Research America Inc
Current assignee: TCL Corp; TCL Research America Inc
Priority date: 2019-12-28
Filing date: 2019-12-28
Publication date: 2021-06-29

Abstract

The invention belongs to the technical field of display, and particularly relates to ink, application of the ink and a preparation method of a quantum dot film. The ink comprises a solvent and quantum dots dispersed in the solvent, wherein the solvent comprises a first organic solvent with a formula I shown in the specification; wherein, in the formula I, R₁At least one selected from alkyl, substituted alkyl, cycloalkyl and substituted cycloalkyl, R₂At least one member selected from the group consisting of a hydrogen atom, an alkyl group, a substituted alkyl group, a cycloalkyl group and a substituted cycloalkyl group. The dispersibility and stability of the ink can be improved by adding the first organic solvent, so that a quantum dot film with densely arranged quantum dots and uniform quantum dots is obtained after the ink forms a film, and the threshold voltage is reducedAnd the light-emitting performance is improved.

Description

Printing ink, application thereof and preparation method of quantum dot film

Technical Field

The invention belongs to the technical field of display, and particularly relates to ink, application of the ink and a preparation method of a quantum dot film.

Background

In recent years, Quantum Dot (QD) luminescent materials play a great role in the fields of LED illumination, liquid crystal display and the like, and quantum dots replace traditional fluorescent powder, thereby effectively improving the color gamut of LEDs and liquid crystal display. Quantum dot light emitting diodes (QLEDs) in which quantum dot light emitting materials are used as light emitting layers have a wide application prospect in the fields of solid state lighting, flat panel display, and the like, and have received extensive attention from the academic and industrial fields.

The solution processing property of the quantum dots enables the quantum dot light-emitting layer to be prepared in various ways such as spin coating, blade coating, spraying, ink-jet printing and the like. The ink-jet printing technology can accurately deposit the quantum dot luminescent material at a proper position according to the required amount, so that the semiconductor material is uniformly deposited to form a thin film layer, the utilization rate of the material is very high, manufacturers can reduce the production cost, the manufacturing process is simplified, mass production is easy to popularize, and the cost is reduced. The ink jet printing technology is an effective method which is recognized at present and can solve the manufacturing problem of the large-size QLED screen.

At present, quantum dots are basically directly dispersed in a solvent in quantum dot ink, but the quantum dot ink obtained by using the solvent with good dispersion stability, such as toluene, chloroform and the like, has very low viscosity and low boiling point, is dissolved in some solvents with higher viscosity, such as long alkane alcohol solvents, has poor dispersion effect on the quantum dots, and the introduction of a polymer additive with insulating property can reduce the charge transmission capability of a quantum dot film. In addition, the quantum dot surface ligand undergoes a certain degree of dissociation equilibrium in the complex solvent environment, and when stored for a certain period of time, the dissociation equilibrium may be disrupted due to a change in the external environment, resulting in a failure in the storage stability.

Therefore, the prior art is in need of improvement.

Disclosure of Invention

The invention aims to provide ink, application thereof and a preparation method of a quantum dot film, and aims to solve the technical problem that the existing quantum dot ink is poor in dispersibility and unstable, so that the quantum dot film is not uniformly formed.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides an ink, which comprises a solvent and quantum dots dispersed in the solvent, wherein the solvent comprises a first organic solvent shown as a formula I;

wherein, in the formula I, R₁At least one selected from alkyl, substituted alkyl, cycloalkyl and substituted cycloalkyl, R₂At least one member selected from the group consisting of a hydrogen atom, an alkyl group, a substituted alkyl group, a cycloalkyl group and a substituted cycloalkyl group.

The solvent of the ink provided by the invention contains a specific first organic solvent shown as a formula I, wherein the first organic solvent contains a phenyl structure and a long hydrocarbon ether chain structure, the viscosity of the first organic solvent can be well matched with the viscosity required by the printing of the ink through the structural groups, and the surface tension of the first organic solvent is larger due to the structure in the first organic solvent, so that the dynamic surface tension of the ink can be effectively adjusted, and the film forming of the ink is more uniform; in addition, the non-polarity of these structures in the first organic solvent allows the quantum dots to be well dispersed in the ink, and R₁And R₂The solubility and the nonpolar adjusting range of the first organic solvent are relatively large, the flexible selection of the type and the content of the specific solvent to match with the printing ink is facilitated, the first organic solvent can volatilize after the printing ink forms a film, the effective charge transmission of the quantum dot film layer can be ensured, and the photoelectric performance is exerted. In a word, the dispersibility and stability of the ink can be improved by adding the first organic solvent, so that a quantum dot film with densely arranged quantum dots and uniformity is obtained after the ink film is formed, the threshold voltage is reduced, and the luminescence performance of the ink is improved.

The invention also provides application of the ink in preparing a quantum dot light-emitting layer in a quantum dot light-emitting diode, wherein the ink is the ink disclosed by the invention.

The dispersibility and stability of the ink can be improved by adding the first organic solvent, so that a quantum dot film with densely arranged quantum dots and uniformity is obtained after the ink forms a film, the threshold voltage is reduced, and the light-emitting performance of the quantum dot film is improved.

Finally, the invention provides a preparation method of the quantum dot film, which comprises the following steps:

providing a substrate;

the printing ink is deposited on the substrate, and then drying treatment is carried out to obtain the quantum dot film.

The preparation method of the quantum dot film provided by the invention is prepared from the special ink, the dispersibility and stability of the ink can be improved by adding the first organic solvent in the ink, and the quantum dot film with densely-arranged and uniform quantum dots is obtained after the ink forms a film, so that the threshold voltage is reduced, and the luminous performance of the quantum dot film is improved.

Drawings

Fig. 1 is a schematic flow chart of a method for preparing a quantum dot thin film according to embodiment 1 of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In one aspect, embodiments of the present invention provide an ink including a solvent and quantum dots dispersed in the solvent, the solvent including a first organic solvent having the following formula I;

The solvent of the ink provided by the embodiment of the invention contains a specific first organic solvent shown as a formula I, the first organic solvent contains a phenyl structure and a long hydrocarbon ether chain structure, and the viscosity of the first organic solvent and the ink can be adjusted through the structural groupsThe viscosity required by printing is well matched, and the surface tension of the ink is larger due to the structure in the first organic solvent, so that the dynamic surface tension of the ink can be effectively adjusted, and the ink can form a film more uniformly; in addition, the non-polarity of these structures in the first organic solvent allows the quantum dots to be well dispersed in the ink, and R₁And R₂The solubility and the nonpolar adjusting range of the first organic solvent are relatively large, the flexible selection of the type and the content of the specific solvent to match with the printing ink is facilitated, the first organic solvent can volatilize after the printing ink forms a film, the effective charge transmission of the quantum dot film layer can be ensured, and the photoelectric performance is exerted. In a word, the dispersibility and stability of the ink can be improved by adding the first organic solvent, so that a quantum dot film with densely arranged quantum dots and uniformity is obtained after the ink film is formed, the threshold voltage is reduced, and the luminescence performance of the ink is improved.

Specifically, the alkyl is an alkyl with a carbon element number of 1-18; such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, cyclopentyl, hexyl, cyclohexyl, isohexyl, heptyl, octyl, nonyl, cyclononyl, decyl, undecyl, dodecyl, hexadecyl, octadecyl, and isomers thereof, and the like. The substituted alkyl is the alkyl with the number of the substituted carbon elements of 1-18, namely the alkyl with the number of the carbon elements of 1-18 is substituted. The cycloalkyl is cycloalkyl with carbon element of 3-18; such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, and the like. The substituted cycloalkyl is a cycloalkyl with the number of the substituted carbon elements of 3-18, namely a group substituted by the cycloalkyl with the number of the carbon elements of 3-18. The viscosity of the alkyl-substituted phenyl ether is gradually increased and the surface tension is gradually decreased within a certain range as the number of carbon elements is increased, and the R is₁And R₂The selection effect is optimal.

In one embodiment, R is₁、R₂The radicals may each be substituted or unsubstituted and may be substituted by one or more identical or different substituents. Said substitutedIn the alkyl group, the substituent is selected from at least one of alkyl, cycloalkyl, aryl, nitro, cyano, amino, -N (R') (R "), halogen, hydroxyl, carboxyl, ester group, carbonyl, alkenyl and alkynyl; in the substituted cycloalkyl, the substituent is selected from at least one of alkyl, cycloalkyl, aryl, nitro, cyano, amino, -N (R') (R "), halogen, hydroxyl, carboxyl, ester, carbonyl, alkenyl and alkynyl. Wherein each R 'and R' is independently an optional alkyl, cycloalkyl, or aryl group. Wherein, the aryl in the above substituents can be phenyl, biphenyl, triphenyl, benzo, naphthyl, anthryl, benzonaphthyl, phenanthryl, fluorenyl, pyrenyl, chrysenyl, perylene, azulenyl and the like.

R is as defined above₁、R₂The group can increase the solubility of the quantum dot, and is convenient for preparing the quantum dot ink for ink-jet printing.

In one embodiment, the first organic solvent is selected from the group consisting of glycidyl-2-methoxyphenyl ether, isoamyl p-tolyl ether, isopropyl 2-isopropylphenyl ether, polyoxyethylene (10) nonylphenyl ether (off-white to pink colored amine liquid), α - (2-epoxyethyl) anisole [ e.g., R-type chiral molecule: (R) -alpha- (2-epoxyethyl) anisole ], (2-dimethylaminoethyl) 4-nonylphenyl ether, 1,2, 2-tetrafluoroethyl-4-methylphenyl ether, ethylene glycol phenyl ether methacrylate, poly (ethylene glycol) phenyl ether acrylate (295.3), 1-isopropoxybenzene, butoxybenzene, dodecyl [2- (trifluoromethyl) phenyl ] ether, hexylphenyl ether, octylphenol polyoxyethylene ether, allyl-p-tolyl ether, allyl-o-tolyl ether, propenyl phenyl ether, tert-butylphenyl ether, polyoxyethylene (2) nonylphenyl ether, tolyl glycidyl ether, 3-ethylphenyl (methyl) ether, polyethylene glycol monononylphenyl ether, beta-hydroxyethylphenyl ether, ethylene glycol monophenyl ether, 2, 3-epoxypropyl-o-tolyl ether, At least one of 2-chloropropylphenyl ether, methyl p-vinyl phenyl ether, isopropylphenyl ether and polyethylene glycol mono-octylphenyl ether.

In one embodiment, the first organic solvent has a boiling point range of 180 ℃ to 380 ℃ (which may be 240 ℃ in particular), and thus may be evaporated from the solvent system to form an inorganic quantum dot thin film.

In one embodiment, the mass fraction of the quantum dots in the ink is in the range of 0.1-20.0%, preferably 4-15%; the mass fraction of the solvent is 20-99.9%. Wherein the first organic solvent accounts for 1-90% of the solvent by mass.

In one embodiment, the ink of the embodiment of the present invention has a viscosity of 0.5 to 60.0mpa.s, preferably in a range of 1.0 to 15.0mpa.s at 25 to 35 ℃; the quantum dots are used for higher luminous efficiency. The surface tension of the ink is between 20 and 60mN/m under the condition of 25 to 35 ℃.

Further, the solvent also comprises a second organic solvent and/or a functional auxiliary agent. The method is used for further adjusting the dispersibility, viscosity, volatilization speed of organic solvent and charge transport performance of quantum dots in the ink.

The second organic solvent is used for adjusting the dispersibility, volatilization speed and film forming property of the inorganic nano material in the printing ink, and is specifically selected from chlorobenzene, o-dichlorobenzene, tetrahydrofuran, anisole, morpholine, toluene, o-xylene, m-xylene, p-xylene, n-hexane, dichloromethane, trichloromethane, 1, 4-dioxane, 1,2 dichloroethane, 1,1, 1-trichloroethane, 1,1,2, 2-tetrachloroethane, tetrahydronaphthalene, decahydronaphthalene, decalin, phenoxytoluene, dodecane, tridecane, tetradecane, pentadecane, hexadecane, 1-methoxynaphthalene, 1-butylnaphthalene, o-dimethoxybenzene, 1-methylnaphthalene, 1, 2-dimethylnaphthalene, cyclohexylbenzene, 1,2, 4-trimethoxybenzene, phenylhexane, 1, at least one of 2-dimethylnaphthalene, 4-isopropylbiphenyl, 2-isopropylnaphthalene, 1-ethylnaphthalene and 1,2,3, 4-tetrahydronaphthalene.

The functional assistant is at least one selected from a charge transport agent, a viscosity regulator and a dispersant. The charge transport agent can improve the charge transport performance after a quantum dot film such as a quantum dot light-emitting layer is prepared from the ink, so that the charge transport is smoother and more effective, and the threshold voltage is reduced, so that electrons and holes can carry out composite radiation luminescence. Preferably, the charge transport agent is selected from at least one of polycarbazole, polyfluorene, polyaniline, polyparaphenylethene (p-phenylene vinylene), polyacetylene, polyparaphenylene, polythiophene, polypyridine, polypyrrole, polycarbazole derivatives, polyfluorene derivatives, polyaniline derivatives, polyparaphenylethene (p-phenylene vinylene) derivatives, polyacetylene derivatives, polyparaphenylene derivatives, polythiophene derivatives, polypyridine derivatives, and polypyrrole derivatives. The viscosity modifier is used for ensuring stable ink release from a nozzle of an ink jet printing head without blockage and has better film forming characteristics, and the viscosity modifier is selected from at least one of polyhydric alcohol, alkyl glycol ether or trimethylolpropane, trimethylolethane, casein and carboxymethyl cellulose; wherein the polyhydric alcohol is at least one of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, 1, 3-butylene glycol, 1, 4-butylene glycol, 1, 5-pentanediol, 2-butene-1, 4-diol, 2-methyl-2-pentanediol, 1,2, 6-hexanetriol, glycerol, polyethylene glycol, dipropylene glycol and polyvinyl alcohol. The alkyl glycol ether is at least one of polyethylene glycol monobutyl ether, diethylene glycol monoethyl ether, dipropylene glycol monomethyl ether and propylene glycol n-propyl ether. The dispersant is used to ensure that the quantum dot material can be uniformly dispersed in an organic solvent and to stabilize the dispersion, and is selected from any one of anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants, and specifically, the anionic surfactants include, but are not limited to, at least one of carboxylates (e.g., ether carboxylates and sulfosuccinates), sulfates (e.g., sodium lauryl sulfate), sulfonates (e.g., dodecylbenzenesulfonate, alpha-alkenylsulfonate, alkyldiphenyloxide disulfonate, fatty acid taurate, alkylnaphthalenesulfonate), phosphates (e.g., phosphate esters of alkyl and aryl alcohols), phosphonates and amine oxide surfactants, and anionic fluorinated surfactants. The cationic surfactant includes, but is not limited to, at least one of quaternary ammonium compounds, cationic amine oxides, ethoxylated fatty amines, and imidazoline surfactants. The nonionic surfactant includes, but is not limited to, at least one of linear or secondary alcohol ethoxylates, alkylphenol ethoxylates, fluorosurfactants, polyoxyethylene esters of fatty acids, polyoxyethylene ethers of fatty amines, polyoxyethylene block copolymers and propoxylated block copolymers, polyoxyethylene and propylsilicone-based surfactants, alkyl polyglycosides, and acetylene polyethylene oxide surfactants. The amphoteric surfactant includes, but is not limited to, at least one of trimethylamine ethylester, sultaine, and aminopropionate.

In one embodiment, the functional additive accounts for 0.1-5% of the mass fraction of the ink; the functional assistant is sufficient to make the boiling point, viscosity and surface tension of the ink within the above numerical ranges.

In one embodiment, the mass ratio of the first organic solvent to the second organic solvent is 1: (1-2). Namely, the added second organic solvent accounts for more than 50 percent of the total mass of the organic solvents (consisting of the first organic solvent and the second organic solvent). Because the viscosity of the first organic solvent is higher and the surface tension is also higher, when the second organic solvent is properly added, the viscosity of the ink can be kept in a printable interval, the static surface tension of the ink is not too high, and the ink can be uniformly spread on a printing substrate.

In the ink, the organic solvent is removed by selecting heating, temperature rising or cooling and/or pressure reducing modes in the post-treatment process.

The quantum dots in the ink are binary or multicomponent semiconductor compounds or mixtures of compounds of groups IV, II-VI, II-V, III-VI, IV-VI, I-III-VI, II-IV-VI and II-IV-V of the periodic table of the elements. Specifically, selected from CdSe, CdS, CdTe, ZnO, ZnSe, ZnS, ZnTe, HgS, HgSe, HgTe, CdZnSe; alternatively, it is selected from InAs, InP, InN, GaN, InSb, InAsP, InGaAs, GaAs, GaP, GaSb, AlP, AlN, AlAs, AlSb, CdSeTe, ZnCdSe, and any combination thereof. Alternatively, the quantum dot is a perovskite nanoparticle material, in particular a luminescent perovskite nanoparticle, or a metal nanoparticle material, or a metal oxide nanoparticle material, or a mixture thereof.

Preferably, the size of the quantum dots is 1-20 nm of average characteristic size. May be of homogeneous mixing type, gradient mixing type, core-shell type or combination type. The quantum dots may be oil-soluble quantum dots; the quantum dots are selected from doped or undoped quantum dots. The quantum dots are combined with ligands, and the ligands are one or more of acid ligands, thiol ligands, amine ligands, (oxy) phosphine ligands, phospholipids, lecithin, polyvinyl pyridine and the like. The acid ligand comprises one or more of decaacid, undecylenic acid, tetradecanoic acid, oleic acid and stearic acid; the thiol ligand comprises one or more of octaalkylthiol, dodecylthiol and octadecylthiol; the amine ligand comprises one or more of oleylamine, octadecylamine and octamine; the (oxy) phosphine ligand comprises one or more of trioctylphosphine and trioctylphosphine.

In another aspect, the embodiment of the present invention provides an application of an ink in preparing a quantum dot light emitting layer in a quantum dot light emitting diode, where the ink is the ink described above.

The dispersibility and stability of the ink can be improved by adding the first organic solvent in the ink disclosed by the embodiment of the invention, so that a quantum dot film with densely-arranged quantum dots and uniformity is obtained after the ink is formed into a film, the threshold voltage is reduced, and the light-emitting performance of the quantum dot film is improved.

Finally, an embodiment of the present invention further provides a method for preparing a quantum dot thin film, as shown in fig. 1, including the following steps:

s01: providing a substrate;

s02: the printing ink provided by the embodiment of the invention is deposited on the substrate, and then drying treatment is carried out to obtain the quantum dot film.

The preparation method of the quantum dot film provided by the embodiment of the invention is prepared from the special ink in the embodiment of the invention, the dispersibility and stability of the ink can be improved by adding the first organic solvent in the ink, so that the quantum dot film with densely arranged and uniform quantum dots is obtained after the ink is formed into a film, the threshold voltage is reduced, and the luminescence performance of the quantum dot film is improved.

Specifically, the method of ink configuration includes: firstly, obtaining a solvent with proper viscosity, boiling point and surface tension; and then dissolving the quantum dots into the solvent according to a predetermined proportion to obtain the quantum dot ink. Specifically, the quantum dots are dispersed in at least one solvent of the first organic solvent shown in the formula I according to the proportion, and the inorganic nano-material printing ink with proper viscosity and surface tension is obtained. The boiling points of all ink compositions were controlled below 450 ℃. And (3) carrying out ink-jet printing on the inorganic nano material luminescent layer film by selecting a proper ink-jet printer. In order to properly release the ink from the nozzles of an ink jet print head without clogging, the amounts of the components are adjusted so that the viscosity of the ink is generally in the range of 0.5cPs to 60cPs at room temperature (25 ℃). In order to properly discharge the ink from the nozzle of the ink jet print head and have good film forming properties, the surface tension is usually in the range of 20 to 60 mN/m.

And (3) post-treatment: and under the action of heating, temperature reduction and/or vacuum pressure reduction, removing the organic solvent shown in the formula I and the like in the film layer, and completely volatilizing other organic substances of the ink composition except the inorganic nano material. The post-treatment time is 0-30 min. The heating temperature is 60-180 ℃. The heating can be realized by controlling the heating mode, such as pulse heating or continuous heating; the temperature of the temperature reduction treatment is 0-20 ℃; vacuum degree of 1X 10^-6And (5) carrying out the Torr to normal pressure to ensure that the solvent in the quantum dot luminescent layer film is completely volatilized, and the quantum dots are not damaged.

Finally, the embodiment of the invention provides a quantum dot light-emitting diode, which comprises an anode, a cathode and a quantum dot light-emitting layer arranged between the anode and the cathode, wherein the quantum dot light-emitting layer is the quantum dot film.

Further, in the above-mentioned quantum dot light emitting diode, a hole function layer (e.g., a hole transport layer, or a stacked hole injection layer and a hole transport layer, where the hole injection layer is adjacent to the anode) may be disposed between the anode and the quantum dot light emitting layer, and an electron function layer (e.g., an electron transport layer, or a stacked electron injection layer and an electron transport layer, where the electron injection layer is adjacent to the cathode) may be disposed between the cathode and the quantum dot light emitting layer.

The invention is described in further detail with reference to a part of the test results, which are described in detail below with reference to specific examples.

Example 1

The mixed solvent of the quantum dot ink in the embodiment is composed of decalin and epoxypropyl-2-methoxyphenyl ether, and various solvents are dehydrated and refined by adopting corresponding methods to ensure that the purity is more than 99.9 percent.

The preparation method of the quantum dot ink of the embodiment comprises the following steps: the following components were added in the following weight parts to an approximately 500mL single-neck flask with stirring in the order: 10 wt% oleylamine stabilised red CdSe/ZnS quantum dots, 45 wt% decalin solvent, 45 wt% glycidyl-2-methoxyphenyl ether; the mixture was stirred for 30 minutes to obtain a quantum dot ink.

Printing the quantum dot ink into a red quantum dot film with a resolution of 200 × 200ppi by an ink-jet printer, heating to 155 deg.C on a hot plate, and vacuum-drying to 1 × 10^-4And volatilizing and drying for 30min under the Torr to obtain the monochromatic quantum dot light-emitting thin film layer.

Example 2

The mixed solvent of the quantum dot ink in the embodiment is composed of hexadecane and isopropyl-2-isopropyl phenyl ether, and various solvents are subjected to water removal and oxygen removal by adopting corresponding methods and refined to the purity of more than 99.9%.

The preparation method of the quantum dot ink of the embodiment comprises the following steps: the following components were added to an approximately 500mL high density polyethylene bottle with stirring in the following order: 10 wt% oleylamine stabilised green CdZnSe/CdZnS, 50 wt% hexadecane, 40 wt% isopropyl-2-isopropylphenyl ether; the mixture was stirred for 30 minutes to obtain a quantum dot ink.

And printing the quantum dot ink into a green quantum dot thin film with the resolution of 200 multiplied by 200ppi by an ink-jet printer, heating the green quantum dot thin film on a hot plate to 180 ℃, and volatilizing and drying the green quantum dot thin film for 30min under nitrogen flow to obtain the monochromatic quantum dot light-emitting thin film.

Example 3

The mixed solvent of the quantum dot ink in the embodiment is composed of pentadecane, o-xylene and hexyl phenyl ether, and various solvents are subjected to water removal and oxygen removal refining by adopting corresponding methods until the purity is more than 99.9%.

The preparation method of the quantum dot ink of the embodiment comprises the following steps: the following components were added to an approximately 500mL high density polyethylene bottle with stirring in the following order: 10 wt% oleylamine stabilized blue CdS/CdZnS (green CdZnSe/CdZnS, red CdSe/ZnS quantum dots), 35 wt% pentadecane, 35 wt% o-xylene, 20 wt% hexylphenyl ether; the mixture was stirred for 30 minutes to obtain a quantum dot ink.

The quantum dot ink is printed into blue, green and red side-by-side quantum dot films with the resolution of 200 multiplied by 200ppi by an ink-jet printer, wherein the thickness of the blue, green and red side-by-side quantum dot films is 20 multiplied by 30 um. Cooling to 15 deg.C, and vacuum of 1X 10^-5And volatilizing and drying for 30min under the Torr to obtain the tricolor quantum dot light-emitting thin film layer.

Example 4

A quantum dot light-emitting diode, comprising a stacked structure of an anode and a cathode which are oppositely arranged, a quantum dot light-emitting layer (the quantum dot light-emitting thin film layer obtained by the preparation method of the above embodiment 1) arranged between the anode and the cathode, an electron transport layer arranged between the cathode and the quantum dot light-emitting layer, and a hole transport layer arranged between the anode and the quantum dot light-emitting layer, wherein the anode is arranged on a substrate. The substrate is made of a glass sheet, the anode is made of an ITO (indium tin oxide) substrate, the hole transport layer is made of a TFB (thin film transistor), the electron transport layer is made of a zinc oxide material, and the cathode is made of Al.

Example 5

A quantum dot light-emitting diode, comprising a stacked structure of an anode and a cathode which are oppositely arranged, a quantum dot light-emitting layer (the quantum dot light-emitting thin film layer obtained by the preparation method of the above embodiment 2) arranged between the anode and the cathode, an electron transport layer arranged between the cathode and the quantum dot light-emitting layer, and a hole transport layer arranged between the anode and the quantum dot light-emitting layer, wherein the anode is arranged on a substrate. The substrate is made of a glass sheet, the anode is made of an ITO (indium tin oxide) substrate, the hole transport layer is made of a TFB (thin film transistor), the electron transport layer is made of a zinc oxide material, and the cathode is made of Al.

Example 6

A quantum dot light-emitting diode, comprising a stacked structure of an anode and a cathode which are oppositely arranged, a quantum dot light-emitting layer (the quantum dot light-emitting thin film layer obtained by the preparation method of the above embodiment 3) arranged between the anode and the cathode, an electron transport layer arranged between the cathode and the quantum dot light-emitting layer, and a hole transport layer arranged between the anode and the quantum dot light-emitting layer, wherein the anode is arranged on a substrate. The substrate is made of a glass sheet, the anode is made of an ITO (indium tin oxide) substrate, the hole transport layer is made of a TFB (thin film transistor), the electron transport layer is made of a zinc oxide material, and the cathode is made of Al.

Comparative example 1

The preparation method of the quantum dot ink of the comparative example includes: the following components were added in the following weight parts to an approximately 500mL single-neck flask with stirring in the order: 10 wt% oleylamine stabilised red CdSe/ZnS quantum dots, 90 wt% decalin solvent; the mixture was stirred for 30 minutes to obtain a quantum dot ink.

A quantum dot light-emitting diode comprises a laminated structure of an anode and a cathode which are oppositely arranged, a quantum dot light-emitting layer (a quantum dot light-emitting thin film layer obtained by the preparation method) arranged between the anode and the cathode, an electron transmission layer arranged between the cathode and the quantum dot light-emitting layer, and a hole transmission layer arranged between the anode and the quantum dot light-emitting layer, wherein the anode is arranged on a substrate. The substrate is made of a glass sheet, the anode is made of an ITO (indium tin oxide) substrate, the hole transport layer is made of a TFB (thin film transistor), the electron transport layer is made of a zinc oxide material, and the cathode is made of Al.

Comparative example 2

The preparation method of the quantum dot ink of the comparative example includes: the following components were added to an approximately 500mL high density polyethylene bottle with stirring in the following order: 10 wt% oleylamine stabilised green CdZnSe/CdZnS, 90 wt% hexadecane; the mixture was stirred for 30 minutes to obtain a quantum dot ink.

Comparative example 3

The preparation method of the quantum dot ink of the embodiment comprises the following steps: the following components were added to an approximately 500mL high density polyethylene bottle with stirring in the following order: 10 wt% oleylamine stabilised blue CdS/CdZnS (green CdZnSe/CdZnS, red CdSe/ZnS quantum dots), 90 wt% pentadecane; the mixture was stirred for 30 minutes to obtain a quantum dot ink.

Performance testing

The quantum dot light emitting diodes of examples 5 to 8 and comparative example were subjected to an External Quantum Efficiency (EQE) test: measured using an EQE optical test instrument. The external quantum efficiency test is the QLED device, namely: anode/hole transport layer/quantum dot light emitting layer/electron transport layer/cathode.

The final data are shown in table 1.

TABLE 1

Item group classification	External Quantum Efficiency (EQE)/(%)
		Example 4	14.5
Comparative example 1	8.1
		Example 5	13.8
Comparative example 2	7.5
		Examples6	14.9
Comparative example 3	9.6

The data in table 1 above show that: the external quantum efficiency of the quantum dot light-emitting diode provided by the embodiments 4-6 (the quantum dot light-emitting layer is made of the quantum dot ink specific to the embodiment of the present invention) is obviously higher than that of the quantum dot light-emitting diode in the comparative example, which shows that the quantum dot light-emitting diode obtained by the embodiment of the present invention has better light-emitting efficiency.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. An ink, comprising a solvent and quantum dots dispersed in the solvent, the solvent comprising a first organic solvent having formula I below;

2. The ink according to claim 1, wherein the alkyl group is an alkyl group having a carbon number of 1 to 18; and/or the presence of a gas in the gas,

the substituted alkyl is the alkyl with the number of the substituted carbon elements of 1-18; and/or the presence of a gas in the gas,

the cycloalkyl is cycloalkyl with carbon element of 3-18; and/or the presence of a gas in the gas,

the substituted cycloalkyl is cycloalkyl with the number of substituted carbon elements of 3-18.

3. The ink according to claim 1, wherein in the substituted alkyl group, the substituent is selected from at least one of an alkyl group, a cycloalkyl group, an aryl group, a nitro group, a cyano group, an amino group, -N (R') (R "), a halogen group, a hydroxyl group, a carboxyl group, an ester group, a carbonyl group, an alkenyl group, and an alkynyl group; and/or the presence of a gas in the gas,

in the substituted cycloalkyl, the substituent is selected from at least one of alkyl, cycloalkyl, aryl, nitro, cyano, amino, -N (R') (R "), halogen, hydroxyl, carboxyl, ester group, carbonyl, alkenyl and alkynyl;

the above R 'and R' are independently selected from at least one of alkyl, cycloalkyl and aryl.

4. The ink of claim 1, wherein the first organic solvent is selected from the group consisting of glycidyl-2-methoxyphenyl ether, isoprene-p-tolyl ether, isopropyl 2-isopropylphenyl ether, polyoxyethylene (10) nonylphenyl ether, α - (2-epoxyethyl) anisole, (2-dimethylaminoethyl) 4-nonylphenyl ether, 1,2, 2-tetrafluoroethyl-4-methylphenyl ether, ethylene glycol phenyl ether methacrylate, poly (ethylene glycol) phenyl ether acrylate, 1-isopropoxybenzene, butoxybenzene, dodecyl [2- (trifluoromethyl) phenyl ] ether, hexylphenyl ether, octylphenol polyoxyethylene ether, allyl-p-tolyl ether, allyl-o-tolyl ether, propenyl phenyl ether, tert-butylphenyl ether, At least one of polyoxyethylene (2) nonylphenyl ether, tolylglycidyl ether, 3-ethylphenyl (methyl) ether, polyethylene glycol monononylphenyl ether, β -hydroxyethylphenyl ether, ethylene glycol monophenyl ether, 2, 3-epoxypropyl-o-tolyl ether, 2-chloropropylphenyl ether, methyl-p-vinylphenyl ether, isopropylphenyl ether and polyethylene glycol monooctylphenyl ether.

5. The ink according to any one of claims 1 to 4, wherein the quantum dots account for 0.1 to 20.0% by mass of the ink; and/or the presence of a gas in the gas,

the first organic solvent accounts for 1-90% of the solvent by mass.

6. The ink according to any one of claims 1 to 4, wherein the solvent further comprises a second organic solvent and/or a functional assistant; wherein the content of the first and second substances,

the second organic solvent is selected from chlorobenzene, o-dichlorobenzene, tetrahydrofuran, anisole, morpholine, toluene, o-xylene, m-xylene, p-xylene, n-hexane, dichloromethane, trichloromethane, 1, 4-dioxane, 1, 2-dichloroethane, 1,1, 1-trichloroethane, 1,1,2, 2-tetrachloroethane, tetrahydronaphthalene, decahydronaphthalene, decalin, phenoxytoluene, dodecane, tridecane, tetradecane, pentadecane, hexadecane, 1-methoxynaphthalene, 1-butylnaphthalene, o-dimethoxybenzene, 1-methylnaphthalene, 1, 2-dimethylnaphthalene, cyclohexylbenzene, 1,2, 4-trimethoxybenzene, phenylhexane, 1, 2-dimethylnaphthalene, 4-isopropylbiphenyl, 2-isopropylnaphthalene, 1-ethylnaphthalene and 1,2, at least one of 3, 4-tetralin; the functional assistant is at least one selected from a charge transport agent, a viscosity regulator and a dispersant.

7. The ink of claim 6, wherein the charge transport agent is selected from at least one of polycarbazole, polyfluorene, polyaniline, polyparaphenylethene (p-phenylene vinylene), polyacetylene, polyparaphenylene, polythiophene, polypyridine, polypyrrole, polycarbazole derivative, polyfluorene derivative, polyaniline derivative, polyparaphenylethene (p-phenylene vinylene) derivative, polyacetylene derivative, polyparaphenylene derivative, polythiophene derivative, polypyridine derivative, and polypyrrole derivative; and/or the presence of a gas in the gas,

the viscosity modifier is selected from at least one of polyhydric alcohol, alkyl glycol ether or trimethylolpropane, trimethylolethane, casein and carboxymethyl cellulose; and/or the presence of a gas in the gas,

the dispersing agent is selected from any one of anionic surfactant, cationic surfactant, nonionic surfactant and amphoteric surfactant.

8. The ink according to claim 6, wherein the functional assistant accounts for 0.1-5% of the ink by mass; and/or the presence of a gas in the gas,

the mass ratio of the first organic solvent to the second organic solvent is 1: (1-2).

9. Use of an ink in the manufacture of quantum dot light emitting layers in quantum dot light emitting diodes, wherein the ink is an ink according to any one of claims 1 to 8.

10. The preparation method of the quantum dot film is characterized by comprising the following steps:

providing a substrate;

depositing the ink according to any one of claims 1 to 8 on the substrate, and then performing a drying process to obtain the quantum dot thin film.