WO2019114829A1

WO2019114829A1 - Quantum dot film and preparation method therefor, and preparation method for quantum dot light-emitting diode

Info

Publication number: WO2019114829A1
Application number: PCT/CN2018/121251
Authority: WO
Inventors: 曹蔚然; 梁柱荣; 杨一行; 向超宇; 钱磊
Original assignee: Tcl集团股份有限公司
Priority date: 2017-12-15
Filing date: 2018-12-14
Publication date: 2019-06-20

Abstract

A quantum dot film and a preparation method therefor, and a preparation method for a quantum dot light-emitting diode. The preparation method for a quantum dot film comprises the following steps: providing a quantum dot prefabricated film, wherein initial ligands are combined on the surface of quantom dots in the quantum dot prefabricated film; and disposing the quantum dot prefabricated film in an airtight apparatus, and introducing gaseous replacement ligands into same to perform gas-phase ligand replacement, so as to obtain a quantum dot film with the replacement ligands combined on the surface of the quantum dot, wherein the replacement ligands contain at least one functional group that can be combined with the surface of the quantum dot.

Description

Quantum dot film, preparation method thereof and preparation method of quantum dot light emitting diode

Technical field

The invention belongs to the field of display technology, and in particular relates to a quantum dot film, a preparation method thereof and a preparation method of the quantum dot light emitting diode.

Background technique

Quantum dot light-emitting diode (QLED) is a new type of light-emitting device that uses quantum dot materials (QDs) as a light-emitting layer, which has incomparable advantages compared with other light-emitting materials, such as Controllable small size effect, ultra-high internal quantum efficiency, excellent color purity, etc., have great application prospects in the future display technology field.

In general, the surface of the quantum dot is linked to the organic ligand by chelation or the like or the inorganic ligand is connected by forming a chemical bond or the like. The surface ligands of quantum dots play a vital role in quantum dot synthesis. On the one hand, surface ligands can passivate defects on the surface of quantum dots and improve the luminescence properties of quantum dots. On the other hand, surface ligands can be reduced. Agglomeration between quantum dots and increasing the ability of quantum dots to disperse in a solvent. In quantum dot light-emitting diode devices, surface ligands will further affect the optoelectronic properties of the device. Therefore, rational selection of ligands on the surface of quantum dots in quantum dot films is an important step to improve the luminous efficiency of quantum dot films and quantum dot light-emitting diodes.

The exchange of ligands on the surface of quantum dots after the end of quantum dot synthesis is currently the more common approach. However, the ligand on the surface of the quantum dot affects its dispersibility in organic solvents. Therefore, the ligand introduced during the ligand exchange process may cause poor dispersion of quantum dots, especially for some chains with shorter chain lengths. In the case of bulk molecules, there is often a problem that quantum dots cannot be dispersed, and thus a quantum dot film having good uniformity cannot be formed. At present, most of the methods of in situ ligand exchange have been reported to use the solution method for ligand exchange. Generally, the quantum dots are first formed into a film, and after the film formation, the quantum dot film is immersed in the ligand solution to be exchanged for distribution. Body exchange. After the ligand exchange is completed, the ligand is washed with a solvent-free solvent to remove excess ligand. The method can select a ligand which is beneficial to improve the luminous efficiency of the quantum dot film and the quantum dot light emitting diode, but the processing process is complicated, and the cost of large-scale production is relatively high, which is suitable for the research work of the prototype device in the laboratory.

technical problem

The object of the present invention is to provide a quantum dot film, a preparation method thereof and a preparation method of the quantum dot light emitting diode, aiming at solving the problem of ligand exchange of the formed quantum dots by the solution method in the existing quantum dot film, which is not only complicated in process, And it is not conducive to the problem of large-scale production.

Technical solution

In order to achieve the above object, the technical solution adopted by the present invention is as follows:

A method for preparing a quantum dot film comprises the following steps:

Providing a quantum dot preformed film, wherein a quantum dot surface in the quantum dot preformed film is bonded with an initial ligand;

The quantum dot pre-formed film is placed in a sealable device, and a gaseous replacement ligand is introduced to perform gas phase ligand replacement to obtain a quantum dot film having a quantum dot surface bonded to the replacement ligand;

Wherein the replacement ligand contains at least one functional group capable of binding to the surface of the quantum dot.

A quantum dot film having a surface ligand attached to a surface of a quantum dot film, the surface ligand being an organic ligand containing at least two functional groups capable of binding to the surface of the quantum dot.

A method for preparing a quantum dot light emitting diode comprises the following steps:

Providing a bottom electrode;

Preparing a quantum dot preformed film on the bottom electrode, wherein the quantum dot surface of the quantum dot preformed film is bonded with an initial ligand;

The quantum dot pre-formed film is placed in a sealable device, and a gaseous replacement ligand is introduced to perform gas phase ligand replacement, thereby obtaining a quantum dot film on the surface of the quantum dot bonded to the replacement ligand to form a quantum dot light-emitting layer; Said replacement ligand contains at least one functional group capable of binding to the surface of the quantum dot;

Preparing a top electrode on the quantum dot luminescent layer;

Wherein the bottom electrode is an anode, the top electrode is a cathode; or the bottom electrode is a cathode, and the top electrode is an anode.

Beneficial effect

The method for preparing a quantum dot film provided by the invention adopts a gas phase method for surface ligand replacement of a quantum dot pre-formed film, and the gas phase method has solvent-free damage relative to the ligand replacement by a solution method (increasing the obtained quantum dot film) Outstanding performance, low cost, simple process and other outstanding advantages. In addition, in the preparation method of the present invention, the gas phase method is used for ligand replacement, the degree of ligand replacement in the gas phase atmosphere is more sufficient, and the selection of the replacement ligand is not limited by the solution environment, and the selection flexibility is good, and the scale can be realized. Chemical and industrial production.

In the quantum dot film provided by the present invention, the surface ligand connected to the surface of the quantum dot is an organic ligand containing at least two functional groups capable of binding to the surface of the quantum dot, thereby improving the solubility and dispersibility of the quantum dot and further improving The stability of the quantum dot film increases the luminous efficiency and overall performance of the quantum dots accordingly.

The preparation method of the quantum dot light-emitting diode provided by the invention is based on the conventional preparation method of the light-emitting device, and the surface ligand replacement of the quantum dot pre-formed film by the gas phase method is not only simple, but also obtained by gas phase method for ligand replacement. The quantum dot luminescent layer is more stable, and provides a more flexible ligand selectivity for the quantum dot luminescent layer, so that it has better comprehensive performance, thereby contributing to improving the photoelectric performance of the device.

Embodiments of the invention

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In one aspect, an embodiment of the present invention provides a method for preparing a quantum dot film, comprising the following steps:

S01: providing a quantum dot preformed film, wherein a quantum dot surface in the quantum dot preformed film is bonded with an initial ligand;

S02: placing the quantum dot pre-formed film in a sealable device, introducing a gaseous replacement ligand, performing gas phase ligand replacement, and obtaining a quantum dot film having a quantum dot surface bonded to the replacement ligand;

In the method for preparing a quantum dot film provided by the embodiment of the present invention, the quantum dot pre-formed film is subjected to surface ligand replacement by a vapor phase method. Compared with the ligand replacement by the solution method, the gas phase method has the advantages of no solvent damage (improving the overall performance of the obtained quantum dot film), low cost, and simple process. In addition, in the preparation method of the embodiment of the invention, the gas phase method is used for ligand replacement, the degree of ligand replacement in the gas phase atmosphere is more sufficient, and the selection of the replacement ligand is not limited by the solution environment, and the selection flexibility is good. Achieve scale and industrial production.

In the embodiment of the present invention, since the surface ligand exchange is realized by the gas phase method, on the one hand, the solvent introduced in the process of surface ligand exchange by the solution method can be prevented from affecting the performance of the quantum dot film, thereby improving the overall performance of the quantum dot film; On the other hand, the gas exchange method for ligand exchange can provide a more flexible surface ligand for the quantum dot film, thereby expanding the range of adaptation of the quantum dot film. For example, by selecting a displacement ligand having good dispersion properties in a solvent, the range of choice of solvent for dispersing quantum dots is expanded; in addition, by selecting a replacement ligand that is better crosslinked with quantum dots, it is possible to avoid When other materials are deposited on the quantum dot film, the introduction of the solvent affects the quantum dot film, thereby expanding the solvent selection range of the material to be deposited.

Specifically, in the above step S01, the quantum dot pre-formed film may be a quantum dot pre-formed film which is introduced into a surface ligand after synthesizing a quantum dot, or may be a quantum dot pre-formed film obtained by ligand exchange by a solution method. The initial ligand bound to the surface of the quantum dot in the quantum dot preformed film, that is, the surface ligand introduced after the synthesis of the quantum dot, or the surface ligand introduced by the solution method, is not strictly in the embodiment of the present invention. Qualified, including but not limited to tetradecene, hexadecene, octadecene, octadecylamine, oleic acid, trioctylamine, trioctylphosphine oxide, trioctylphosphine, octadecylphosphonic acid And at least one of 9-octadecenylamine and decylundecanoic acid.

The quantum dots in the quantum dot preformed film are a II-VI compound, a III-V compound, a II-V compound, a III-VI compound, a IV-VI compound, a I-III-VI compound, II- One or more of an IV-VI compound or a Group IV element. Specifically, the II-VI compound (semiconductor material) includes CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, PbS, PbSe, PbTe, but is not limited thereto, and may be other binary , ternary, quaternary II-VI compound; III-V compound (semiconductor material) nanocrystals include but are not limited to GaP, GaAs, InP, InAss, but are not limited thereto, and may be other binary, three Meta- and quaternary III-V compounds.

As a preferred embodiment, the quantum dots are doped or undoped inorganic perovskite semiconductors, and/or organic-inorganic hybrid perovskite semiconductors. Specifically, the inorganic perovskite semiconductor has a structural formula of AMX ₃ , wherein A is a Cs ⁺ ion, and M is a divalent metal cation, including but not limited to Pb ²⁺ , Sn ²⁺ , Cu ²⁺ , Ni ²⁺ , Cd ²⁺ , Cr ²⁺ , Mn ²⁺ , Co ²⁺ , Fe ²⁺ , Ge ²⁺ , Yb ²⁺ , Eu ²⁺ , X are halogen anions, including but not limited to Cl ^- , Br ^- , I ^- . The organic-inorganic hybrid perovskite semiconductor has the structural formula BMX ₃ , wherein B is an organic amine cation including, but not limited to, CH ₃ (CH ₂ ) _n-2 NH ₃ ⁺ (n≥2) or NH ₃ (CH ₂ ) _n NH ₃ ²⁺ (n ≥ 2). When n=2, the inorganic metal halide octahedron MX ₆ ^{4- is} connected by a co-topping manner, the metal cation M is located in the body center of the halogen octahedron, and the organic amine cation B is filled in the space between the octahedrons to form an infinite extension. The three-dimensional structure; when n>2, the inorganic metal halide octahedron MX ₆ ^4- connected in a co-top manner extends in a two-dimensional direction to form a layered structure, intercalated with an organic amine cation bilayer (protonated single) An amine) or an organic amine cation monolayer (protonated bisamine), the organic layer and the inorganic layer overlap each other to form a stable two-dimensional layered structure; M is a divalent metal cation, including but not limited to Pb ²⁺ , Sn ^{2 +} , Cu ²⁺ , Ni ²⁺ , Cd ²⁺ , Cr ²⁺ , Mn ²⁺ , Co ²⁺ , Fe ²⁺ , Ge ²⁺ , Yb ²⁺ , Eu ²⁺ , X are halogen anions, including but not Limited to Cl ^- , Br ^- , I ^- .

In the above step S02, the quantum dot prefabricated film is placed in a sealable device, and the sealable device is used as a reaction device, on the one hand, preventing entry of water and oxygen, and affecting ligand replacement; more importantly, The sealed environment of the sealable device can form a pressurized or vacuum environment to promote the progress of the ligand replacement reaction. In theory, as long as a closed chamber capable of achieving a certain degree of vacuum can be used in the embodiment of the present invention, it may be a low vacuum sealed chamber or a high vacuum sealed chamber, which is not strictly limited in the embodiment of the present invention.

Embodiments of the present invention provide a material basis for ligand exchange by introducing a gaseous replacement ligand. Further, by adjusting the pressure, temperature, and partial pressure of the replacement ligand in the sealable device, gas phase ligand replacement is performed to make the initial ligand of the quantum dot surface and the replacement ligand in the quantum dot preformed film. Ligand exchange occurs, and finally a quantum dot film in which the surface of the quantum dot is bonded to the replacement ligand is obtained.

Preferably, embodiments of the invention employ gas phase ligand replacement in a vacuum environment. Specifically, in the process of replacing the vapor phase ligand, the internal pressure of the sealable device is 10 ^-5 to 10 ³ Pa, and the partial pressure of the replacement ligand is 10 ^-4 to 10 ² Pa. By controlling the internal pressure of the sealable device, the content of the product in the positive direction is effectively reduced; and by adjusting the partial pressure of the replacement ligand, a suitable content of the replacement ligand in the reaction environment is ensured, thereby The double layer of the raw material source causes the displacement reaction to proceed in the positive direction (the direction in which the quantum dots are bonded to the replacement ligand). Further preferably, in the process of replacing the gas phase ligand, the internal pressure of the sealable device is 10 ^-4 to 10 ² Pa, and the partial pressure of the replacement ligand is 0.01-10 Pa, which is more favorable for the displacement reaction. In the positive direction.

In the embodiment of the present invention, the gas phase ligand replacement may be carried out at a normal temperature. Preferably, in order to increase the reaction rate, it may be subjected to heat treatment. In summary, during the gas phase ligand replacement, the internal temperature of the sealable device is 5 to 200 °C.

In the embodiment of the present invention, the time of the gas phase ligand replacement varies according to the initial ligand, the type of the replacement ligand, and the internal pressure of the sealable device and the partial pressure of the replacement ligand, and may be in the range of 0.5-360 min. between.

In the embodiment of the present invention, the replacement ligand is a gaseous substance, and the gaseous replacement ligand may be a gaseous ligand at normal temperature and pressure, or may be converted from a liquid or solid replacement ligand. As an embodiment, the gaseous replacement ligand is prepared by evaporating or boiling the liquid replacement ligand. In another embodiment, the gaseous replacement ligand is prepared by liquefying the solid replacement ligand or directly performing sublimation treatment.

In the above preparation method, the replacement ligand contains at least one functional group capable of binding to the surface of the quantum dot. As an implementation, the replacement ligand is an organic ligand. Preferably, the replacement ligand is an organic ligand containing at least two functional groups capable of binding to the surface of the quantum dot, that is, an organic ligand containing at least two reactive functional groups. Adjacent quantum dots are cross-linked by two or more reactive functional groups of the organic ligand to form a strong quantum dot cross-linking system.

In a specific embodiment, the chemical structure of the replacement ligand is X ₁ -RX ₂ , wherein X ₁ and X ₂ are functional groups connectable to the surface of the quantum dot, and R is a hydrocarbon group or a hydrocarbon derivative. For example, R may be selected from saturated alkanes, unsaturated alkanes, aromatic hydrocarbons and derivatives thereof containing any organic functional group or no organic functional group. Preferably, the X _{1 is} selected from the group consisting of a halogen atom, a hydroxyl group, an ether group, a thiol group, a thioether group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a nitro group, a nitroso group, an amino group, an imido group, a sulfo group, an acyl group. At least one of a nitroxyl group, a sulfonyl group, a cyano group, an isocyano group, a decyl group, a phosphino group, a phosphoric acid group, a decyl group, an epoxy group, an azo group, a vinyl group, an ethynyl group, and an aromatic ring group. X _{2 is} selected from the group consisting of a halogen atom, a hydroxyl group, an ether group, a thiol group, a thioether group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a nitro group, a nitroso group, an amino group, an imido group, a sulfo group, an acyl group, a nitro group, At least one of a sulfonyl group, a cyano group, an isocyano group, a decyl group, a phosphino group, a phosphoric acid group, a decyl group, an epoxy group, an azo group, a vinyl group, an ethynyl group, and an aromatic ring group. The preferred reactive functional group not only has good reactivity, but also can effectively improve the replacement efficiency of the initial ligand with the surface, and can achieve cross-linking with adjacent quantum dots. More preferably, X ₁ and X _{2 are} selected from one of a halogen atom, -SH, -COOH, -NH ₂ , -OH, -NO ₂ , -SO ₃ H, a phosphino group, a phosphate group.

In a specific embodiment, the substitution ligand containing a functional group capable of binding to the surface of the quantum dot may include 1-propanethiol, 1-butanethiol, 1-hexylthiol, 1-octylthiol, 1- At least one of dodecyl mercaptan, 1-octadecyl mercaptan, octylamine, and butylamine. Of course, an organic ligand containing at least two functional groups capable of binding to the surface of the quantum dot, such as an organic ligand including two functional groups capable of bonding to the surface of the quantum dot, including 1,2-ethanedithiol, is more preferred. , 1,4-butanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, 1,4-benzenedithiol, 1,4-benzenedithiol, mercaptoethylamine , mercaptopropylamine, thioglycolic acid, 3-mercaptopropionic acid, 3-mercaptobutyric acid, 6-mercaptohexanoic acid, 8-mercaptooctanoic acid, 11-decylundecanoic acid, ethanolamine, 1,2-ethylenediamine, 1,3 -propylenediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 4-mercaptobenzoic acid, mercaptoglycerol, 1-trimethylamine ethyl mercaptan, nitro Phenyl mercaptan, sulfophenyl mercaptan, mercaptophenylacetic acid, nitrobenzenesulfonic acid, phenylenediamine, mercaptoaniline, nitroaniline, sulfoaniline, terephthalic acid, terephthalic acid, aminobenzoic acid, 4 -(diphenylphosphino)benzoic acid, p-phenylenediamine, m-phenylenediamine, terephthalonitrile, isophthalonitrile, terephthalamide, isophthalaldehyde, terephthalic acid, isophthalic acid Dicarboxylic acid, 2-mercaptobenzoic acid, 4-mercaptobenzoic acid, 4-aminobenzoic acid, 4-hydroxyl Benzoic acid, p-sulfobenzoic acid, p-nitrobenzoic acid, 4-mercaptoaniline, 4-hydroxyaniline, 4-cyanoaniline, 4-mercaptotylic acid, 4-hydroxystyrene acid, 2-(4- Hydroxyphenyl)pyridine, 2-chloro-5-cyanothiazole, 2-amino-3-cyanothiophene, 1,5-diindenylnaphthalene, 1,5-dihydroxynaphthalene, 1,4-naphthalene dicarboxylic acid, 2,6-naphthalene disulfonic acid. The replacement ligand includes two or more organic ligands capable of binding to the surface of the quantum dot, including 3-amino-5-mercapto-1,2,4-triazole, 2,3-dimercaptosuccinic acid, 2 ,3-dihydroxysuccinic acid, pentaerythritol tetrakis(3-mercaptopropionic acid) ester, pentaerythritol tetraacrylate, pentaerythritol tetrabenzoate, polydipentaerythritol pentaacrylate, tetra [3-(3,5-di-tertiary) Butyl-4-hydroxyphenyl)propionic acid] pentaerythritol ester, 3,5-dimethylhydrazine-2,6-diaminotoluene, 2,4-diamino-6-mercaptopyrimidine, 2-chloro-4-amino Pyrimidine, dimethyl 2,3-dichlorosuccinate, diethyl 2,3-dichlorosuccinate, 1,2-bis(4-aminophenoxy)ethane and poly(2,5- At least one of dodecanoyl-1,4-phenylacetylene-2-(11-hydroxyundecyloxycarbonyl)-1,4-phenylacetylene). Preferably, the substitution ligand contains at least two functional groups capable of binding to the surface of the quantum dot, and on the one hand has a good material state (it is gaseous at normal temperature or is easily converted into a gaseous state), on the other hand, the above replacement ligand has a higher Good reactivity, especially with the original organic ligands on the surface of the synthesized quantum dots, enables efficient displacement reactions under gas phase conditions.

In one embodiment, the ligand is replaced with a conjugated ligand, i.e., ligand substitution chemical structural formula of X ₁ -RX _2, R is a hydrocarbon group or a hydrocarbon group having a conjugated derivative group. Such a conjugated ligand crosslinks the quantum dots, so that the solubility, dispersibility and conductivity of the quantum dots can be better balanced, further improving the stability of the quantum dot film and the carrier transport ability, and correspondingly improving Luminous efficiency and improved overall performance. Compared with common ligands, conjugated ligands have more decentralized molecular packing due to the delocalization effect of electrons, which facilitates the efficient transfer of intermolecular charges and enhances the transport of carriers inside the device, thereby improving the device. Luminescence performance. In addition, the steric hindrance of conjugated ligands tends to be large, the distance between quantum dots is large, and the transport effect of carriers between quantum dots is not ideal. Therefore, the use of conjugated ligands instead of ordinary ligands is simple. The performance improvement of the device is limited, so the quantum dots are made closer by cross-linking. Moreover, in the conventional cross-linked quantum dot film, one of the functions of cross-linking is to form a closely spaced quantum dot film structure, and quantum dots and quantum dots are connected to each other, but in the crosslinked quantum dot film, the crosslinking mode is And the type and nature of the intermediates forming the crosslinked structure often cause great differences in the transport of carriers. For example, when quantum dots are crosslinked by a long-chain alkane structure, although a quantum dot crosslinked film can be formed, Due to the poor carrier transport effect of long-chain alkanes, the carrier transport properties of the crosslinked films are not good. Therefore, when a conjugated and crosslinked structure is used, the connecting bridge between the quantum dots is a conjugated structure having an electron delocalization effect, and the carrier transport in the structure can be multi-channel transmission, which can be very The carrier transmission effect is improved to a large extent, thereby improving device performance.

Further, in the conjugated ligand of the above chemical structure formula X ₁ -RX ₂ , the X ₁ and X ₂ are bonded to the surface of the quantum dot, and the connection means includes one of bonding, electrostatic adsorption, chelation or a plurality, and the X ₁ and X _{2 are} independently selected from a halogen atom, a hydroxyl group, an ether group, a thiol group, a thioether group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a nitro group, a nitroso group, an amino group, an imido group. , sulfo, acyl, nitroxyl, sulfonyl, cyano, isocyano, decyl, phosphino, phosphino, decyl, epoxy, azo, vinyl, ethynyl, aromatic At least one; that is, X ₁ and X ₂ may be the same group as described above, or may be a different group. Preferably, X ₁ is the same as X ₂ , and both sides have the same activity and can react with the quantum dots; if the activities of the two sides are inconsistent, it is necessary to control the amount of the reactants and the reaction parameters. When the high-activity functional groups are all reacted and the reaction parameters are adjusted, the reaction parameters can be adjusted. Low activity functional groups react with quantum dots.

Meanwhile, in the above conjugated ligand, R is a hydrocarbon group or a hydrocarbon derivative having a conjugated group, that is, an organic unit structure having a conjugation effect (electron delocalization effect), such as an unsaturated hydrocarbon group or a hydrocarbon derivative, Conjugation effects include, but are not limited to, one or more of π-π conjugate, p-π conjugate, σ-π conjugate, σ-p conjugate, pp conjugate; the organic having a conjugation effect The unit structure includes, but is not limited to, a linear structure and/or a ring structure in which double bonds and single bonds are alternately arranged, wherein a triple bond structure may further be included in the structure (in particular, it should be understood that according to the classical organic chemistry theory) In the present case, the benzene ring structure is also considered to be one of a cyclic conjugated structure in which three carbon-carbon single bonds and three carbon-carbon double bonds are alternately connected to each other, wherein the cyclic structure may be an ordered ring The structure may also be a heterocyclic structure; specifically, the functional group contained in the organic unit structure having a conjugation effect includes, but not limited to, a conjugated ring (such as a benzene ring), -C=C-, -C≡C-, One or more of -C=O, -N=N-, -C≡N, -C=N-; in particular, the conjugate effect The organic unit structure may contain a ring structure, wherein the ring structure includes, but is not limited to, a benzene ring structure, a phenanthrene structure, a naphthalene structure, a fluorene structure, a fluorene structure, a benzyl structure, a fluorene structure, a terpene structure, a fluorene structure, a fluorene structure. , fluoranthene structure, benzofluorene structure, benzofluoranthene structure, benzofluorene structure, indenofluorene structure, dibenzopyrene structure, benzopyrene structure, pyrrole structure, pyridine structure, pyridazine structure, furan structure, Thiophene structure, fluorene structure, porphin structure, porphyrin structure, thiazole structure, imidazole structure, pyrazine structure, pyrimidine structure, quinoline structure, isoquinoline structure, pteridine structure, acridine structure, oxazole structure, hydrazine One or more of an azole structure, a triazole structure, a benzofuran structure, a benzothiophene structure, a benzothiazole structure, a benzoxazole structure, a benzopyrrole structure, and a benzimidazole structure.

Still more preferably, the substitution ligand of the embodiment of the present invention comprises at least one of the compounds represented by any one of the following formulas 1-4, wherein R0, R1, R1', R2, R2', R3, R3', R4, R4', R5, R5' are independently selected from hydrocarbyl or hydrocarbyl derivatives; X1, X1', X2, X2', X3, X3' are reactive functional groups capable of binding to quantum dots. Preferred replacement ligands, the chain ends containing a plurality of reactive functional groups, and when the quantum dot material such as a quantum dot film is prepared by in situ ligand replacement, a plurality of the reactive functional groups are combined with one or more quantum dots to form a crosslink. The quantum dot film structure can not only increase the exchange rate of the ligand molecules on the surface of the quantum dot, but also improve the binding force of the ligand on the surface of the quantum dot to the quantum dot, thereby improving the quantum dot film or quantum dot light emitting diode device thus obtained. Stability.

In the embodiment of the present invention, R0, R1, R1', R2, R2', R3, R3', R4, R4', R5, R5' may be independently selected from a saturated or unsaturated hydrocarbon group or a hydrocarbon derivative such as an alkane. a base, an alkene group, an alkyne group, an aryl group, a heteroaryl group, a derivative thereof, and the like. In the embodiment of the present invention, X1, X1', X2, X2', X3, X3' are functional groups capable of chelation with the surface of the quantum dot, preferably having a reactive reactivity with the quantum dot, and are easy to be In situ replacement with the original ligand introduced during quantum dot synthesis improves the displacement rate.

Specifically, the replacement ligand includes, but is not limited to, 2,3-dimercaptosuccinic acid, 2,3-dihydroxysuccinic acid, pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetraacrylate, pentaerythritol IV Benzoic acid ester, polydipentaerythritol pentaacrylate, tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] pentaerythritol ester, 3,5-dimethylhydrazine-2,6- Diaminotoluene, 2,4-diamino-6-mercaptopyrimidine, 2-chloro-4-aminopyrimidine, dimethyl 2,3-dichlorosuccinate, diethyl 2,3-dichlorosuccinate At least one of 1,2-bis(4-aminophenoxy)ethane. Preferred replacement ligands, when preparing quantum dot materials such as quantum dot light-emitting layers by means of in-situ ligand replacement, can efficiently exchange efficiently with the initial ligands of quantum dots introduced during the synthesis, and at the same time The reactive functional group has strong activity and high binding force with quantum dots, and then the replacement ligand bonded to the surface of the same quantum dot combines with a plurality of quantum dots to form a stable quantum dot light-emitting layer, thereby improving the performance of the film layer. Sex and dispersion performance.

As another preferred case, the compound represented by Formula 1-4 is a conjugated ligand. Wherein, Formula 1, Formula 2, Formula 3, and Formula 4 contain at least one conjugated group, specifically, in Formula 1, R is a conjugated group; in Formula 2, at least one of R1 and R2 is conjugated. In the formula 3, at least one of R, R1, R1', R2, R2' is a conjugated group; in Formula 4, R1, R1', R2, R2', R3, R3', R4, R4 At least one of ', R5, R5' is a conjugated group. The conjugated group has been described above, for example, R, R1, R1', R2, R2', R3, R3', R4, R4', R5, R5' may be independently selected from unsaturated hydrocarbyl or hydrocarbyl derivatives such as olefins. Alkyne, alkyne group, aryl group, heteroaryl group and derivatives thereof, and the like. X1, X1', X2, X2', X3, X3' are functional groups capable of chelation with the surface of the quantum dot, and preferably, the reactive functional group includes a halogen atom, -SH, -COOH, -NH ₂ , At least one of -OH, -NO ₂ , -SO ₃ H, a phosphino group, a phosphoric acid group, an ether group, and a cyano group, but is not limited thereto. The preferred reactive functional groups have better reactivity with the quantum dots, and are easily replaced with the original ligand introduced during quantum dot synthesis to increase the replacement rate.

Specifically, when the replacement ligand is a conjugated ligand, including but not limited to p-phenylenediamine, m-phenylenediamine, terephthalonitrile, isophthalonitrile, terephthalic acid, isophthalaldehyde , terephthalic acid, isophthalic acid, 2-mercaptobenzoic acid, 4-mercaptobenzoic acid, 4-aminobenzoic acid, 4-hydroxybenzoic acid, p-sulfobenzoic acid, p-nitrobenzoic acid, 4-fluorenyl Aniline, 4-hydroxyaniline, 4-cyanoaniline, 4-mercaptotylic acid, 4-hydroxystyrene acid, 2-(4-hydroxyphenyl)pyridine, 2-chloro-5-cyanothiazole, 2- Amino-3-cyanothiophene, 1,5-diindenylnaphthalene, 1,5-dihydroxynaphthalene, 1,4-naphthalene dicarboxylic acid, 2,6-naphthalene disulfonic acid, 3-amino-5-mercapto-1 At least one of at least one of 2,4-triazole. The preferred conjugated ligand is capable of efficiently performing high-efficiency replacement with the initial ligand of the quantum dot introduced during the synthesis, and at the same time, because the activity of the reactive functional group is preferred, the quantum dot has a high binding force, and The replacement ligand bound to the surface of the same quantum dot combines with a plurality of quantum dots to form a stable quantum dot film, which improves the performance stability and dispersion performance of the film.

In another embodiment of the invention, the replacement ligand is a compound of formula I:

Wherein, in the formula I, n is an integer greater than or equal to 1; when n=1, at least two of R1, R2, R3, R4, R1', R2', R3', R4' are compatible with quantum dots, Or a ligand-bound functional group on the surface of the quantum dot; when n>1, at least one of R1, R2, R3, R4, R1', R2', R3', R4' is capable of interacting with a quantum dot or a quantum dot surface Ligand-bound functional group.

The replacement ligand described in the above formula I is a long-chain compound having a conjugated structure. On the one hand, it can simultaneously anchor a plurality of quantum dots to form a crosslinked quantum dot film having cross-linking dispersibility to improve The stability of the quantum dot film; on the other hand, the surface ligand has a large conjugate structure, which can effectively improve carrier transport, thereby improving the luminescence properties of the device.

Further, in the substitution ligand of the above formula I, a functional group of R1, R2, R3, R4, R1', R2', R3', R4' which can bind to a quantum dot or a ligand on the surface of a quantum dot or Is a functional group linked to a saturated carbon chain or an unsaturated carbon chain, specifically selected from a halogen atom, a hydroxyl group, an ether group, a thiol group, a thioether group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a nitro group, a nitroso group, an amino group, Imino, thio, sulfo, acyl, amide, nitroxyl, sulfonyl, cyano, isocyano, decyl, phosphino, phosphate, decyl, epoxy, azo, vinyl Or one or more of an ethynyl group and an aromatic ring group; further preferably, the functional group is a mercapto group, a hydroxyl group, a carboxyl group, an amino group, a cyano group, and if R1, R2, R3, R4, R1', R2', R3', R4' contain a carbon chain in addition to the functional group, and the carbon chain is preferably an unsaturated carbon chain structure such as a vinyl group, an ethynyl group, a benzene ring or the like because the unsaturated structure can have a conjugation effect. Thereby promoting the transmission of electrons.

Specifically, in the substitution ligand represented by Formula I, n = 1-4.

The specific method for obtaining the substitution ligand of the long-chain compound represented by the above formula I is not considered in the present case as long as the compound can be obtained. In general, in the examples of the present invention, the compound represented by the above formula I can be obtained by a reaction of condensation or polymerization or the like from a monomer composed of 1 to 4 units represented by the following formula II.

Preferably, the substitution ligand represented by the above formula I has the following preferred structure in consideration of steric hindrance and the like:

Among R1, R2, R3, R4, R1', R2', R3', R4', there are 6 preferred cases: (1) R1 and R3' are capable of binding to a quantum dot or a ligand on the surface of a quantum dot. a functional group, the other is H, the specific structural formula is as shown in Formula Ia; (2) R1 and R2' are functional groups capable of binding to a quantum dot or a ligand on the surface of a quantum dot, and others are H, and the specific structural formula is as shown in Formula Ib; (3) R1, R3 and R1' are functional groups which can bind to quantum dots or ligands on the surface of quantum dots, others are H, and the specific structural formula is as shown in formula Ic; (4) R1, R3, R1' and R3' a functional group that can bind to a quantum dot or a ligand on the surface of a quantum dot, the others are H, and the specific structural formula is as shown in Formula Id; (5) R1, R2, and R1' are compatible with quantum dots or quantum dot surfaces. a body-bound functional group, the others are H, and the specific structural formula is as shown in Formula Ie; (6) R1, R2, R1' and R2' are functional groups which can bind to quantum dots or ligands on the surface of quantum dots, and others are H, The specific structural formula is as shown in the formula If.

As a more preferred embodiment, the structure of three preferred compounds is as follows: Formula Ig, Formula Ih, and Formula Ii are shown below.

In one embodiment of the present invention, the replacement ligand described in the above formula I may be poly(2,5-dodecanoyl-1,4-phenyleneacetylene-2-(11-hydroxyundecyloxycarbonyl) )-1,4-phenylacetylene); the corresponding English name is:

Poly(2,5-didodecanoxy-1,4-phenyleneethynylene-2-(11-hydroxyundecyloxycarbonyl)-1,4-phenyleneethynylene).

For the conventional quantum dot cross-linking method, generally, a reaction occurs between the ligands on the surface of the quantum dot, or a ligand having a carbon-carbon double bond is introduced into the quantum dot, and a crosslinking agent is added to pass the ultraviolet light. Or heating or other methods to promote the reaction to form a cross-linked quantum dot film, which is very easy to cause agglomeration between quantum dots during the cross-linking between quantum dots, and is prone to some quantum dots in some cross-linked regions. In some cross-linking regions, quantum dot aggregation is less, and although a so-called crosslinked film can be formed, the uniformity of the film layer and the uniformity of light emission of the device are adversely affected by the uneven cross-linking between the quantum dots. In the embodiment of the present invention, the replacement ligand of the formula I of the present invention is introduced, and since it has a long chain and has a certain spatial configuration, it can form a network structure, and has a plurality of quantum and quantum The point-bound functional group can anchor the quantum dot only to the long chain of the surface ligand (here, it can be understood that the long-chain surface ligand is a rope, and a plurality of quantum dots are embedded on the rope), the quantum dot There is no reunion between them, thus avoiding the drawbacks of the traditional cross-linking method. In general, long-chain polymers are not very conductive, but long-chain compounds with a conjugated structure contain a large number of unsaturated bonds, and the delocalized electrons can be freely transported, thereby greatly improving their conductivity; The long-chain surface ligand of the embodiment of the present invention has a structure in which a benzene ring and a carbon-carbon triple bond are arranged in a long-chain compound, and a plurality of functional groups coordinated to the quantum dots are provided thereon. As a result, the long-chain surface ligand has high conductivity, and the quantum dots can not only be cross-linked to the chain, but also the long-chain surface ligand can serve as a channel for carrier transport, improving carrier transport performance. In turn, the uniformity of illumination of the device is improved.

Correspondingly, an embodiment of the present invention provides a quantum dot film, wherein a surface of the quantum dot film is connected with a surface ligand, and the surface ligand is composed of at least two functional groups capable of combining with the surface of the quantum dot. Organic ligands.

In the quantum dot film provided by the embodiment of the invention, the surface ligand connected to the surface of the quantum dot is an organic ligand containing at least two functional groups capable of binding to the surface of the quantum dot, thereby improving the solubility and dispersibility of the quantum dot. The stability of the quantum dot film is further improved, and the luminous efficiency and overall performance of the quantum dots are correspondingly improved.

Further, in an embodiment, the surface ligand attached to the surface of the quantum dot in the quantum dot film is a conjugated ligand.

That is, a quantum dot film, the quantum dot surface of the quantum dot film is connected with a conjugated ligand of the following structural formula:

X ₁ -RX ₂

Wherein X ₁ and X ₂ are functional groups capable of bonding to the surface of the quantum dot; and R is a hydrocarbon group or a hydrocarbon derivative having a conjugated group.

In the above quantum dot film, the surface of the quantum dot is bonded to a specific conjugated ligand, and the conjugated ligand contains a conjugated group, and the conjugated ligand crosslinks the quantum dots, so that the solubility and dispersion of the quantum dots are achieved. The ability to achieve a better balance with its conductivity, further improve the stability of the quantum dot film and the carrier transport capacity, correspondingly improve the luminous efficiency and improve its overall performance.

In the above quantum dot film, X ₁ and X _{2 are} independently selected from a halogen atom, a hydroxyl group, an ether group, a thiol group, a thioether group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a nitro group, a nitroso group, an amino group, an imine group. Base, sulfo group, acyl group, nitroxyl group, sulfonyl group, cyano group, isocyano group, decyl group, phosphino group, phosphoric acid group, fluorenyl group, epoxy group, azo group, vinyl group, ethynyl group, aromatic ring group At least one of the R; the R comprising at least one of a conjugated ring, -C=C-, -C≡C-, -C=O, -N=N-, -C≡N-, -C=N- a group; or the R is a linear structure and/or a cyclic structure including alternating double bonds and single bonds. Specific Selection of Conjugated Ligands The preparation of quantum dot films has been described in detail.

Further, in an embodiment, the surface ligand attached to the surface of the quantum dot in the quantum dot film is a compound represented by the following formula I:

Where n is an integer greater than or equal to 1; when n=1, at least two of R1, R2, R3, R4, R1', R2', R3', R4' are compatible with quantum dots, or quantum dot surfaces Ligand-bound functional group; when n>1, at least one of R1, R2, R3, R4, R1', R2', R3', R4' is capable of binding to a quantum dot or a ligand on the surface of a quantum dot. Functional group.

The surface ligand is a long-chain compound containing a conjugated structure. On the one hand, it can anchor a plurality of quantum dots at the same time to form a crosslinked quantum dot film, which has cross-linking dispersibility to improve the stability of the quantum dot film. On the other hand, the surface ligand has a large conjugate structure, which can effectively improve carrier transport, thereby improving the luminescence properties of the device. The compound of formula I above may be bonded to the surface of the quantum dot or to the initial ligand on the surface of the quantum dot. In the above quantum dot film, since the surface of the quantum dot contained therein is bonded to the surface ligand represented by the above formula I, and the initial ligand on the surface of the quantum dot is bonded to the surface ligand represented by the above formula I, It has good stability, and the surface ligand can effectively enhance the transport of carriers, so it has good luminescent properties.

Further, in the compound of the formula I, n=1-4; ligands which can be bonded to quantum dots or quantum dot surfaces in R1, R2, R3, R4, R1', R2', R3', R4' The functional group to be bonded includes: a halogen atom, a hydroxyl group, an ether group, a thiol group, a thioether group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group, a nitro group, a nitroso group, an amino group, an imido group, a thio group, a sulfo group, an acyl group, At least one of an amide group, a nitroxyl group, a sulfonyl group, a cyano group, an isocyano group, a decyl group, a phosphino group, a phosphoric acid group, a fluorenyl group, an epoxy group, an azo group, a vinyl group, an ethynyl group, or an aromatic ring group. . Specific Selection of Compounds Described by Formula I The preparation of the above quantum dot films has been described in detail.

The quantum dot film provided by the embodiment of the invention can be obtained by the method for preparing the quantum dot film of the above gas phase method according to the embodiment of the invention, and the surface ligand exchange can be realized by the gas phase method, on the one hand, the surface ligand can be avoided by the solution method. The solvent introduced during the exchange affects the performance of the quantum dot film, thereby improving the overall performance of the quantum dot film; on the other hand, the gas exchange method for ligand exchange can provide a more flexible surface ligand for the quantum dot film, thereby expanding The range of adaptation of quantum dot films. For example, by selecting a displacement ligand having good dispersion properties in a solvent, the range of choice of solvent for dispersing quantum dots is expanded; in addition, by selecting a replacement ligand that is better crosslinked with quantum dots, it is possible to avoid When other materials are deposited on the quantum dot film, the introduction of the solvent affects the quantum dot film, thereby expanding the solvent selection range of the material to be deposited.

The quantum dot film is composed of crosslinked quantum dots, the crosslinked quantum dots including quantum dots and an organic ligand crosslinked with the quantum dots, wherein the organic ligand contains at least two reactive functional groups, The organic ligand and the quantum dots are crosslinked by the reactive functional group. Since the organic ligand contains at least two reactive functional groups, it is possible to simultaneously crosslink with two or more quantum dots. Adjacent quantum dots are crosslinked by the same and/or different organic ligands to form a strong quantum dot cross-linking system. The quantum dot film having the above characteristics can be prevented from being affected by the preparation method or solvent of the upper functional layer when preparing other functional layers on the surface of the quantum dot film. Further, when the quantum dot film is used for a QLED device, the functional layer material adjacent to the quantum dot emitting layer, the solvent of the functional layer material, and the type of ink formed are no longer limited, thereby expanding the functional layer material of the QLED device. And the range of inks to choose from.

The quantum dot film provided by the embodiment of the invention can be applied to a quantum dot light emitting diode, and can also be applied to other electronic devices of a content sub-dot layer, including but not limited to a quantum dot detector, a quantum dot sensor, a quantum dot solar cell, and a quantum. Point lasers, etc.

An embodiment of the present invention further provides a quantum dot light emitting diode comprising a bottom electrode, a top electrode, and a quantum dot light emitting layer between the bottom electrode and the top electrode, wherein the quantum dot light emitting layer is described by the embodiment of the present invention. A quantum dot film or a quantum dot film obtained by the method for producing a quantum dot film according to an embodiment of the present invention.

The quantum dot light emitting diode provided by the present invention comprises a quantum dot film prepared by the above method of the embodiment of the present invention. Since the photoelectric performance of the quantum dot film obtained by the gas phase method for ligand replacement is more stable, the photoelectric performance of the light-emitting device can be improved. At the same time, the quantum dot film has a more flexible ligand selectivity, and thus can break through the limitations imposed by the quantum dot surface ligand on the light emitting device and the display screen.

In the embodiment of the present invention, the QLED device may be a positive QLED device or an inverted QLED device. As an implementation, the QLED device can be a positive QLED device, ie the bottom electrode is an anode and the top electrode is a cathode. As another implementation, the QLED device can be an inverted QLED device, ie the bottom electrode is a cathode and the top electrode is an anode.

Based on the above embodiment, further preferably, the QLED device further includes a functional modification layer including at least one of a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer. . The hole injection layer and the hole transport layer are disposed between the anode and the quantum dot light-emitting layer, and the electron injection layer and the electron transport layer are disposed between the quantum dot light-emitting layer and the cathode.

Further preferably, the QLED device of the embodiment of the present invention further includes an interface modification layer, wherein the interface modification layer is at least one of an electron blocking layer, a hole blocking layer, an electrode modification layer, and an isolation protection layer.

Correspondingly, a method for preparing a quantum dot light emitting diode comprises the following steps:

E01: providing a bottom electrode;

E02: preparing a quantum dot preformed film on the bottom electrode, wherein a quantum dot surface of the quantum dot preformed film is bonded with an initial ligand;

E03: placing the quantum dot pre-formed film in a sealable device, introducing a gaseous replacement ligand, performing gas phase ligand replacement, and obtaining a quantum dot film on the surface of the quantum dot bonded to the replacement ligand to form a quantum dot light-emitting layer The replacement ligand contains at least one functional group capable of binding to the surface of the quantum dot;

Preparing a top electrode on the quantum dot luminescent layer;

The preparation method of the quantum dot light-emitting diode provided by the embodiment of the invention is based on the conventional preparation method of the light-emitting device, and the surface ligand replacement of the quantum dot pre-formed film by the gas phase method is not simple, and the gas phase method is used for ligand replacement. The obtained quantum dot luminescent layer has better comprehensive performance, thereby facilitating the improvement of the photoelectric performance of the device.

Preferably, the above preparation method further comprises providing a functional layer between the quantum dot luminescent layer and the electrode, for example, when the bottom electrode is an anode and the top electrode is a cathode, before preparing the quantum dot pre-formed film on the bottom electrode, a step of preparing a hole functional layer on the bottom electrode, such as depositing at least one of a hole injection layer and a hole transport layer; and before the top electrode is prepared on the quantum dot light-emitting layer, The step of preparing an electronic functional layer on the light-emitting layer further includes depositing at least one of an electron transport layer and an electron injection layer on the quantum dot light-emitting layer. When the bottom electrode is a cathode and the top electrode is an anode, before the preparation of the quantum dot preformed film on the bottom electrode, the method further comprises the steps of preparing an electronic functional layer on the bottom electrode, such as including depositing an electron transport layer and an electron injection layer. At least one layer; before preparing the top electrode, before preparing the top electrode on the luminescent layer of the quantum dot, further comprising the step of preparing a hole functional layer on the quantum dot luminescent layer, as included in the quantum dot luminescent layer At least one of a hole injection layer and a hole transport layer is deposited.

The electronic functional layer is preferably deposited by solution processing to increase the film thickness uniformity of the electronic functional layer, thereby imparting excellent stability to the electronic functional layer. Specifically, the electronic functional layer is prepared by: providing an electronic functional material solution, depositing the electronic functional material solution on the surface of the quantum dot emitting layer, and annealing to prepare an electronic functional layer. Wherein, since the quantum dots in the quantum dot film form a crosslinking system, in the step of preparing the electronic functional layer on the quantum dot light-emitting layer, the solvent of the electronic functional material solution can be flexibly selected. Specifically, the solvent of the electronic functional material solution may be selected from any of the following solvents without considering the properties of the quantum dots. Preferably, the solvent of the electronic functional material solution includes, but is not limited to, hexane, cyclohexane, heptane, n-octane, isooctane, pentane, methylpentane, ethylpentane, cyclopentane, Methylcyclopentane, ethylcyclopentane, benzene, toluene, xylene, ethylbenzene, dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, chloropropane, dichloro Propane, trichloropropane, chlorobutane, dibromomethane, tribromomethane, ethyl bromide, bromopropane, methyl iodide, chlorobenzene, bromobenzene, benzyl chloride, benzyl bromide, trifluorotoluene, methanol, ethanol, propanol , isopropanol, butanol, isobutanol, sec-butanol, tert-butanol, pentanol, isoamyl alcohol, tert-amyl alcohol, cyclohexanol, octanol, benzyl alcohol, ethylene glycol, phenol, o-cresol , diethyl ether, anisole, phenethyl ether, diphenyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, propylene glycol methyl ether, ethylene glycol diethyl ether, hydroxyethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, Acetaldehyde, benzaldehyde, acetone, methyl ethyl ketone, cyclohexanone, acetophenone, formic acid, acetic acid, ethyl acetate, diethyl oxalate, diethyl malonate, Acid propyl ester, methyl propyl ester, butyl acetate, methyl amyl acetate, nitrobenzene, acetonitrile, diethylamine, triethylamine, aniline, pyridine, picoline, ethylenediamine, N, N-di Methylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, hexamethylphosphoramide, carbon disulfide, methyl sulfide, ethyl sulfide, dimethyl sulfoxide, thiol At least one of ethanethiol and methoxytetrahydrofuran.

The above-mentioned QLED device may be packaged in a partial package, a full package, or not. The embodiment of the present invention is not strictly limited.

In step E03, the quantum dot pre-formed film is placed in a sealable device, and the sealable device serves as a reaction device, on the one hand, prevents entry of water and oxygen, and affects ligand replacement; more importantly, The sealed environment of the sealable device can form a pressurized or vacuum environment to promote the progress of the ligand replacement reaction. In theory, as long as a closed chamber capable of achieving a certain degree of vacuum can be used in the embodiment of the present invention, it may be a low vacuum sealed chamber or a high vacuum sealed chamber, which is not strictly limited in the embodiment of the present invention. Embodiments of the present invention provide a material basis for ligand exchange by introducing a gaseous replacement ligand. Further, by adjusting the pressure, temperature, and partial pressure of the replacement ligand in the sealable device, gas phase ligand replacement is performed to make the initial ligand of the quantum dot surface and the replacement ligand in the quantum dot preformed film. Ligand exchange occurs, and finally a quantum dot film in which the surface of the quantum dot is bonded to the replacement ligand is obtained.

Preferably, embodiments of the invention employ gas phase ligand replacement in a vacuum environment. Specifically, in the process of replacing the vapor phase ligand, the internal pressure of the sealable device is 10 ^-5 to 10 ³ Pa, and the partial pressure of the replacement ligand is 10 ^-4 to 10 ² Pa. By controlling the internal pressure of the sealable device, the content of the product in the positive direction is effectively reduced; and by adjusting the partial pressure of the replacement ligand, a suitable content of the replacement ligand in the reaction environment is ensured, thereby The double layer of the raw material source causes the displacement reaction to proceed in the positive direction (the direction in which the quantum dots are bonded to the replacement ligand). Further preferably, in the process of replacing the gas phase ligand, the internal pressure of the sealable device is 10 ^-4 to 10 ² Pa, and the partial pressure of the replacement ligand is 0.01-10 Pa, which is more favorable for the displacement reaction. In the positive direction. In the embodiment of the present invention, the gas phase ligand replacement may be carried out at a normal temperature. Preferably, in order to increase the reaction rate, it may be subjected to heat treatment. In summary, during the gas phase ligand replacement, the internal temperature of the sealable device is 5 to 200 °C. In the embodiment of the present invention, the time of the gas phase ligand replacement varies according to the initial ligand, the type of the replacement ligand, and the internal pressure of the sealable device and the partial pressure of the replacement ligand, and may be in the range of 0.5-360 min. between.

In the above method for preparing a quantum dot light emitting diode, the replacement ligand in step E03 has been described in detail in the method for preparing a quantum dot film. In the method for preparing the quantum dot light emitting diode, the replacement ligand may preferably be selected to contain at least two. An organic ligand of a reactive functional group.

In one embodiment, a method of fabricating an inversion QLED device includes the following steps:

S1: providing a gaseous replacement ligand and a cathode deposited with a quantum dot preformed film, wherein a quantum dot surface in the quantum dot preformed film is bonded with an initial ligand, and the replacement ligand is at least two reactive functional groups. Organic ligand

S2: placing the quantum dot pre-formed film in a sealable device, introducing a gaseous replacement ligand, and performing gas phase ligand replacement to obtain a quantum dot film having a quantum dot surface bonded to the replacement ligand;

S3: preparing a hole functional layer on the quantum dot film;

S4: preparing an anode on the hole functional layer.

Wherein, the hole function layer includes at least one of a hole injection layer and a hole transport layer.

In one embodiment, a method of fabricating a positive QLED device includes the following steps:

S1: providing a gaseous replacement ligand and an anode deposited with a quantum dot preformed film, wherein a quantum dot surface in the quantum dot preformed film is bonded with an initial ligand, the replacement ligand being at least two reactive functional groups Replacement ligand;

S3: preparing an electronic functional layer on the quantum dot film;

S4: preparing a cathode on the electronic functional layer.

Wherein, the electronic functional layer includes at least one of an electron injection layer and an electron transport layer.

According to the preparation method of the positive or negative QLED device provided by the embodiment of the invention, on the basis of the conventional preparation method of the device, the quantum dot luminescent layer is prepared by surface ligand replacement of the quantum dot prefabricated film by a vapor phase method, which is not only simple in process, but also The quantum dot luminescent layer obtained by the gas phase method for ligand replacement has better comprehensive performance, thereby facilitating the improvement of the photoelectric performance of the QLED device. Specifically, the method for preparing the quantum dot light-emitting layer, on the one hand, performs surface ligand replacement of the initial ligand and the replacement ligand on the surface of the formed quantum dot (quantum dot preformed film) by a vapor phase method. Compared with the ligand replacement by the solution method, the gas phase method has the advantages of no solvent damage (improving the overall performance of the obtained quantum dot film), low cost, and simple process. In addition, the gas phase method is used for ligand replacement, the degree of ligand replacement in the gas phase atmosphere is more sufficient, and the selection of the replacement ligand is not limited by the solution environment, and the selection flexibility is good, and the scale and industrial production can be realized. On the other hand, the replacement ligand can more fully and efficiently exchange ligand with the initial ligand in the quantum dot preformed film in a gas phase environment, thereby improving exchange efficiency, and at the same time, the gas phase ligand environment is favorable for adjacent Crosslinking between quantum dots is achieved by different reactive functional groups of the same displacement ligand, and the quantum dots are crosslinked to form a strong quantum dot crosslinking system.

In the preparation method of the above-mentioned inverse QLED device or positive QLED device, the replacement ligand of the organic ligand containing at least two reactive functional groups has been elaborated in the preparation method of the quantum dot film, and the quantum dot preformed film is in the sealable device. The conditions for performing gas phase ligand replacement are also described in detail above. For example, in the process of gas phase ligand replacement, the internal pressure of the sealable device is 10 ^-4 to 10 ² Pa, and the partial pressure of the replacement ligand is 0.01-10 Pa, the internal temperature of the sealable device It is 5 to 200 °C. The time of the gas phase ligand replacement may vary depending on the initial ligand, the type of the replacement ligand, and the internal pressure of the sealable device, and the partial pressure of the replacement ligand, and may be between 0.5 and 360 minutes.

In one embodiment, a method for fabricating a quantum dot light emitting diode, wherein the quantum dot light emitting diode is a white light quantum dot light emitting diode, comprising the following steps:

S1: providing a bottom electrode;

S2: preparing a quantum dot pre-formed film on the bottom electrode, wherein the quantum dot pre-formed film is connected with an initial ligand on the surface of the quantum dot, and the quantum dot pre-formed film is placed in a sealable device, and a gas-state replacement is introduced. The ligand is subjected to gas phase ligand replacement to obtain a first quantum dot film in which the quantum dot surface is bonded to the replacement ligand, and the replacement ligand is an organic ligand containing at least two functional groups capable of binding to the surface of the quantum dot. ;

S3: preparing a N-layer stacked quantum dot film by using the first layer of quantum dot film to obtain a light-emitting layer; or, using the first layer of quantum dot film to prepare an N-1 layer stack a quantum dot film, preparing an organic light-emitting film on the N-1 layer quantum dot film to obtain a light-emitting layer;

Wherein, N is a positive integer, 2 ≤ N ≤ 10; and the luminescent laminate composite emits white light;

S4: preparing a top electrode on the light emitting laminate;

The preparation method of the white light quantum dot light-emitting diode provided by the embodiment of the invention, in the preparation of the light-emitting laminate, the surface ligand replacement of each quantum dot pre-formed film by the vapor phase method is not only simple, but the replacement ligand can be connected at least two. The quantum dots are such that the quantum dots are crosslinked after film formation, and the film after crosslinking is not affected by the solvent of the upper film, so that the light-emitting laminate of the multilayer quantum dot film stack structure can be prepared by the solution method to realize white light emission. .

In the preparation method of the above-mentioned white light quantum dot light-emitting diode, a replacement ligand of an organic ligand containing at least two reactive functional groups has been described in detail in the preparation method of the quantum dot film, and the quantum dot preformed film is subjected to a gas phase ligand in a sealable device. The conditions for the replacement are also described in detail above. For example, in the process of gas phase ligand replacement, the internal pressure of the sealable device is 10 ^-4 to 10 ² Pa, and the partial pressure of the replacement ligand is 0.01-10 Pa, the internal temperature of the sealable device It is 5 to 200 °C. The time of the gas phase ligand replacement may vary depending on the initial ligand, the type of the replacement ligand, and the internal pressure of the sealable device, and the partial pressure of the replacement ligand, and may be between 0.5 and 360 minutes.

Specifically, after each layer of the quantum dot film is prepared, the quantum dot film needs to be subjected to ligand replacement by gas phase reaction, and then another quantum dot film is deposited, and the replacement ligand can simultaneously connect two or more. Quantum dots, after completion of the treatment, a light-emitting stack having ligand crosslinks is obtained. Preferably, the Nth layer in the light emitting laminate may be an organic light emitting film, that is, an organic light emitting film is prepared on the N-1th quantum dot film. The N-th quantum dot film layer is not a ligand exchange, and thus may be a quantum dot luminescent material or an organic luminescent material, and each layer smaller than N is a quantum dot luminescent material because ligand exchange is required.

A quantum dot light emitting diode, wherein the quantum dot light emitting diode is a white light quantum dot light emitting diode, and the quantum dot light emitting diode is produced by the above preparation method. The white light quantum dot light-emitting diode of the embodiment of the invention can realize white light illumination by containing the light-emitting layer stack composed of the multilayer quantum dot film stack structure, and overcome the existing red, green and blue three-color (or more light-emitting color) quantum dot mixing preparation and mixing. In the quantum dot luminescent layer, the problem of energy transfer easily occurs between quantum dots, thereby reducing the influence of different electric fields on the luminescent color of the device.

In the embodiment of the present invention, the white light quantum dot light emitting diode may be a positive white light quantum dot light emitting diode or an inverted white light quantum dot light emitting diode. As an implementation, the white light quantum dot light emitting diode is a positive white light quantum dot light emitting diode, that is, the bottom electrode is an anode, and the top electrode is a cathode. In another embodiment, the white light quantum dot light emitting diode is an inverted white light quantum dot light emitting diode, i.e., the bottom electrode is a cathode and the top electrode is an anode.

In the white light quantum dot light emitting diode, N is an integer greater than or equal to 2 and less than or equal to 10, and specifically may be 2, 3, 4, 5, 6, 7, 8, and 9 values. Further preferably, in the N-layer quantum dot film, 2 ≤ N ≤ 5; and the thickness of the quantum dot film per layer is preferably 2 to 80 nm.

The preparation of the quantum dot light emitting diodes of the embodiments of the present invention can be performed on a substrate, which is a rigid substrate or a flexible substrate, including but not limited to one of glass and metal foil. Or a variety of; the flexible substrate includes, but is not limited to, polyethylene terephthalate (PET), polyethylene terephthalate (PEN), polyetheretherketone (PEEK), polyphenylene Ethylene (PS), polyethersulfone (PES), polycarbonate (PC), polyarylate (PAT), polyarylate (PAR), polyimide (PI), polyvinyl chloride (PV), One or more of polyethylene (PE), polyvinylpyrrolidone (PVP), and textile fibers.

In the above preparation method, the bottom electrode and the top electrode are individually selected from at least one of a metal material, a carbon material, and a metal oxide. The metal material includes, but is not limited to, Al, Ag, Cu, Mo, Au, or an alloy thereof; the carbon material includes, but is not limited to, one or more of graphite, carbon nanotubes, graphene, and carbon fibers. . The metal oxide is a doped or undoped metal oxide. Specifically, as an implementation, the doped metal oxide includes, but is not limited to, indium doped tin oxide (ITO), fluorine doped oxidation. Tin (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), One or more of aluminum-doped magnesium oxide (AMO). In another embodiment, the bottom electrode and the top electrode may be separately selected from a composite electrode containing a metal interlayer in a transparent metal oxide, wherein the transparent metal oxide may be a doped transparent metal oxide, It may be an undoped transparent metal oxide. The composite electrode includes, but is not limited to, AZO/Ag/AZO, AZO/Al/AZO, ITO/Ag/ITO, ITO/Al/ITO, ZnO/Ag/ZnO, ZnO/Al/ZnO, TiO ₂ /Ag/TiO ₂ , one or more of TiO ₂ /Al/TiO ₂ , ZnS/Ag/ZnS, ZnS/Al/ZnS, TiO ₂ /Ag/TiO ₂ , TiO ₂ /Al/TiO ₂ . In the embodiment of the present invention, according to the light-emitting characteristics of different quantum dot light-emitting diodes, including a top emitting device, a bottom emitting device, and a fully transparent device, a bottom electrode and a top electrode of different materials are selected, and quantum dot light emitting with different device structures is constructed. diode.

The hole injection layer is selected from an organic material having a hole injecting ability. The hole injecting material for preparing the hole injecting layer includes, but not limited to, poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT:PSS), copper phthalocyanine (CuPc), 2,3, 5,6-tetrafluoro-7,7',8,8'-tetracyanoquinone-dimethane (F4-TCNQ), 2,3,6,7,10,11-hexacyano-1,4,5 One or more of 8,8,9,12-hexaazatriphenylene (HATCN), a transition metal oxide, and a transition metal sulfur compound. Wherein, the transition metal oxide includes, but is not limited to, at least one of MoO ₃ , VO ₂ , WO ₃ , CrO ₃ , CuO; the metal sulfur-based compound includes, but not limited to, MoS ₂ , MoSe ₂ , WS ₂ , At least one of WSe ₂ and CuS.

The hole transport layer is selected from organic materials having hole transporting ability, including but not limited to poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB) , polyvinyl carbazole (PVK), poly(N,N'bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (poly-TPD), poly(9,9- Dioctyl fluorene-co-bis-N,N-phenyl-1,4-phenylenediamine) (PFB), 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA) , 4,4'-bis(9-carbazole)biphenyl (CBP), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl -4,4'-diamine (TPD), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB At least one of graphene doped, undoped graphene, C60. As another embodiment, the hole transport layer 4 is selected from inorganic materials having hole transporting ability, including but not limited to doping Or at least one of undoped MoO ₃ , VO ₂ , WO ₃ , CrO ₃ , CuO, MoS ₂ , MoSe ₂ , WS ₂ , WSe ₂ , and CuS.

The electron transport layer is selected from materials having electron transport properties, preferably inorganic materials or organic materials having electron transport properties including, but not limited to, n-type ZnO, TiO ₂ , SnO ₂ , Ta ₂ O ₃ , At least one of AlZnO, ZnSnO, InSnO, Ca, Ba, CsF, LiF, Cs ₂ CO ₃ ; the organic material includes not limited to Alq ₃ , TPBi, BCP, BPhen, PBD, TAZ, OXD-7, 3TPYMB, At least one of BP4mPy, TmPyPB, BmPyPhB, and TQB.

The top electrode, the bottom electrode, the hole injection layer, the hole transport layer, the electron transport layer, the electron injection layer, and the deposition method of the quantum dot pre-formed film may be implemented by a chemical method or a physical method, wherein the chemical method includes However, it is not limited to one or more of chemical vapor deposition, continuous ion layer adsorption and reaction, anodization, electrolytic deposition, and coprecipitation; and the physical methods include, but are not limited to, physical coating or solution processing. The solution processing method includes, but is not limited to, spin coating, printing, knife coating, immersion pulling, immersion, spray coating, roll coating, casting, slit coating, strip coating The physical coating method includes, but is not limited to, one of a thermal evaporation coating method, an electron beam evaporation coating method, a magnetron sputtering method, a multi-arc ion plating method, a physical vapor deposition method, an atomic layer deposition method, and a pulse laser deposition method. Or a variety.

Finally, an embodiment of the present invention further provides a display screen including the above QLED device.

The display screen provided by the embodiment of the invention can improve the stability of the device because it contains the above quantum dot film. When the quantum dot film in the display screen contains a conjugated ligand, the quantum dot film forms a strong quantum dot cross-linking system, which can further improve the stability of the quantum dot luminescent film; meanwhile, the gas phase method is used for ligand replacement. The photoelectric stability of the obtained quantum dot film is further improved. Therefore, the photoelectric performance of the printed quantum dot display is improved.

Example 1

A method for preparing a quantum dot film, comprising the steps of:

Providing a CdSe quantum dot prefabricated film, transferring the quantum dot prefabricated film into a vacuum chamber, and introducing a 1,2-ethanedithiol gas, wherein the pressure inside the vacuum chamber is 5 Pa, 1,2-ethanedithiol The partial pressure of the gas was 1 Pa, the temperature inside the chamber was 25 ° C, and the treatment time was 30 min. After the treatment, the mixture was taken out to obtain a CdSe quantum dot light-emitting layer in which the ligand was replaced with 1,2-ethanedithiol.

Example 2

A method for preparing an inverse structure quantum dot light emitting diode comprises the following steps:

Printing a CdSe quantum dot preformed film on an ITO cathode;

The CdSe quantum dot preformed film was subjected to gas phase ligand replacement according to the method described in Example 1, to prepare a crosslinked CdSe quantum dot light-emitting layer having a surface ligand of 1,2-ethanedithiol;

An Al anode is vapor-deposited on the CdSe quantum dot light-emitting layer to obtain an inverted-structure quantum dot light-emitting diode.

Example 3

A method for preparing a positive structure quantum dot light emitting diode comprises the following steps:

A PEDOT hole injection layer, a TFB hole transport layer, and a CdSe quantum dot pre-formed film coated with an oleic acid ligand are sequentially printed on the ITO cathode;

A ZnO electron transport layer is printed on the CdSe quantum dot light-emitting layer, and finally an Al cathode is evaporated to obtain a positive-structure quantum dot light-emitting diode.

Example 4

A ZnO electron transport layer and a CdSe quantum dot prefabricated film coated with an oleic acid ligand are sequentially printed on the ITO cathode;

A TFB hole transport layer and a PEDOT hole injection layer are sequentially printed on the CdSe quantum dot light-emitting layer, and finally an Al anode is vapor-deposited to obtain an inverted-structure quantum dot light-emitting diode.

Example 5

A method for preparing a quantum dot film, comprising the steps of:

Providing a CdSe quantum dot preformed film, wherein the initial ligand of the surface of the quantum dot in the quantum dot preformed film is mercaptoethylamine;

Transferring the quantum dot preformed film into a vacuum chamber and introducing a gaseous poly(2,5-dodecanoyl-1,4-phenylacetylene-2-(11-hydroxyundecyloxycarbonyl)-1 , 4-phenylacetylene), wherein the pressure inside the vacuum chamber is 5 Pa, poly(2,5-dodecanoyl-1,4-phenyleneacetylene-2-(11-hydroxyundecyloxycarbonyl) The partial pressure of the -1,4-phenylacetylene gas was 1 Pa, the temperature inside the chamber was 25 ° C, the treatment time was 30 min, and after the treatment was completed, a CdSe quantum dot film was obtained.

Example 6

PEDOT hole injection layer, TFB hole transport layer, CdSe quantum dot prefabricated film are sequentially printed on the ITO cathode;

The CdSe quantum dot preformed film was subjected to gas phase ligand replacement according to the method described in Example 5, and the surface ligand was prepared as poly(2,5-dodecanoyl-1,4-phenyleneacetylene-2-(11). a crosslinked CdSe quantum dot luminescent layer of -hydroxyundecyloxycarbonyl)-1,4-benzene acetylene);

In this embodiment, by introducing a conjugated poly(2,5-dodecanoyl-1,4-phenyliacetylene-2-(11-hydroxyundecyloxycarbonyl)-1 into a quantum dot film , 4-phenyl acetylene), on the one hand, capable of simultaneously anchoring a plurality of quantum dots to form a crosslinked quantum dot film having cross-linking dispersibility to improve the stability of the quantum dot film; The huge conjugate structure can effectively improve the carrier transport, thereby improving the luminescence performance of the device.

Example 7

A method for preparing a white light quantum dot light emitting diode comprises the following steps:

PEDOT hole injection layer, TFB hole transport layer, first layer CdSe red light quantum dot prefabricated film are sequentially printed on the ITO anode;

The first layer of CdSe red light quantum dot prefabricated film prepared above is transferred into a vacuum chamber, and 1,2-ethanedithiol gas is introduced, wherein the pressure inside the chamber is 5 Pa, and the fraction of 1,2-ethanedithiol gas The pressure is 1 Pa, the temperature inside the chamber is 25 ° C, the treatment time is 30 min, and after the treatment is completed, the first layer of CdSe red light quantum dot film after ligand replacement is obtained;

Printing a second layer of CdSe green light quantum dot preform film on the first layer of CdSe red light quantum dot film replaced by the ligand, and then transferring the second layer of CdSe green light quantum dot film into the vacuum chamber, and introducing 1,2-B Dithiol gas, wherein the pressure inside the chamber is 5 Pa, the partial pressure of 1,2-ethanedithiol gas is 1 Pa, the temperature inside the chamber is 25 ° C, the treatment time is 30 min, and after the treatment is completed, the ligand replacement is performed. a second layer of CdSe green light quantum dot film;

A third layer of CdSe blue quantum dot preform film is printed on the second layer of CdSe green light quantum dot emitting layer with ligand replacement, and then the third layer of CdSe basket quantum dot film is transferred into the vacuum chamber, and 1,2- Ethylenedithiol gas, wherein the pressure inside the chamber is 5 Pa, the partial pressure of 1,2-ethanedithiol gas is 1 Pa, the temperature inside the chamber is 25 ° C, the treatment time is 30 min, and after the treatment is completed, the ligand is obtained. a third layer of CdSe blue quantum dot film after replacement; the three layers of quantum dot films of different colors constitute a light-emitting layer formed in a white light quantum dot light-emitting diode;

A ZnO electron transport layer is printed on the third layer of the CdSe blue quantum dot luminescent film, and finally an Al cathode is evaporated to obtain a white light quantum dot light emitting diode.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

A method for preparing a quantum dot film, comprising the steps of:

Providing a quantum dot preformed film, wherein a quantum dot surface in the quantum dot preformed film is bonded with an initial ligand;

The quantum dot pre-formed film is placed in a sealable device, and a gaseous replacement ligand is introduced to perform gas phase ligand replacement to obtain a quantum dot film having a quantum dot surface bonded to the replacement ligand;

Wherein the replacement ligand contains at least one functional group capable of binding to the surface of the quantum dot.
The method of producing a quantum dot film according to claim 1, wherein the replacement ligand is an organic ligand containing at least two functional groups capable of binding to the surface of the quantum dot.
The method for preparing a quantum dot film according to claim 2, wherein the chemical structure of the replacement ligand is X 1 -RX 2 ; wherein X 1 and X 2 are functional groups connectable to the surface of the quantum dot, R It is a hydrocarbon group or a hydrocarbon group derivative.
The method for preparing a quantum dot film according to claim 3, wherein in the chemical structural formula of the substitution ligand, X 1 and X 2 are independently selected from a halogen atom, a hydroxyl group, an ether group, a thiol group, and a thioether. Base, aldehyde group, carbonyl group, carboxyl group, ester group, nitro group, nitroso group, amino group, imino group, sulfo group, acyl group, nitroxyl group, sulfonyl group, cyano group, isocyano group, decyl group, phosphino group, phosphoric acid At least one of a group, a fluorenyl group, an epoxy group, an azo group, a vinyl group, an ethynyl group, an aromatic ring group; and/or,

R is a hydrocarbon group or a hydrocarbon group derivative having a conjugated group.
A method of producing a quantum dot film according to claim 4, wherein, in the chemical structural formula of said replacement ligand, R is a hydrocarbon group or a hydrocarbon derivative having a conjugated group, said R comprising a total of a yoke ring, at least one of -C=C-, -C≡C-, -C=O, -N=N-, -C≡N-, -C=N-; or

The R is a linear structure and/or a cyclic structure including alternately arranged double bonds and single bonds.
The method of producing a quantum dot film according to claim 2, wherein the replacement ligand is a compound represented by the following formula I:

Where n is an integer greater than or equal to 1; when n=1, at least two of R1, R2, R3, R4, R1', R2', R3', R4' are compatible with quantum dots, or quantum dot surfaces Ligand-bound functional group; when n>1, at least one of R1, R2, R3, R4, R1', R2', R3', R4' is capable of binding to a quantum dot or a ligand on the surface of a quantum dot. Functional group.
The method of preparing a quantum dot film according to claim 6, wherein in the compound of the formula I, n = 1-4; and/or

The functional groups in R1, R2, R3, R4, R1', R2', R3', R4' which can bind to quantum dots or ligands on the surface of quantum dots include: halogen atoms, hydroxyl groups, ether groups, mercapto groups, thioether groups. , aldehyde, carbonyl, carboxyl, ester, nitro, nitroso, amino, imino, thio, sulfo, acyl, amide, nitroxyl, sulfonyl, cyano, isocyano, fluorenyl At least one of a phosphino group, a phosphate group, a decyl group, an epoxy group, an azo group, a vinyl group, an ethynyl group, and an aromatic ring group.
The method of preparing a quantum dot film according to claim 1, wherein the replacement ligand is selected from the group consisting of 1-propanethiol, 1-butyl mercaptan, 1-hexyl mercaptan, 1-octyl mercaptan, and 1- At least one of dodecyl mercaptan, 1-octadecyl mercaptan, octylamine, and butylamine; and/or,

The replacement ligand is selected from the group consisting of 1,2-ethanedithiol, 1,4-butanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, 1,4-benzenedisulfide. Alcohol, 1,4-xylylenedithiol, mercaptoethylamine, mercaptopropylamine, thioglycolic acid, 3-mercaptopropionic acid, 3-mercaptobutyric acid, 6-mercaptohexanoic acid, 8-mercaptooctanoic acid, 11-fluorenyl eleven Acid, ethanolamine, 1,2-ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 4-mercaptobenzoic acid, Mercaptoglycerol, 1-trimethylamine ethanethiol, nitrobenzenethiol, sulfophenylthiol, nonylphenylacetic acid, nitrobenzenesulfonic acid, phenylenediamine, mercaptoaniline, nitroaniline, sulfanilide, Terephthalic acid, terephthalic acid, aminobenzoic acid, 4-(diphenylphosphino)benzoic acid, p-phenylenediamine, m-phenylenediamine, terephthalonitrile, isophthalonitrile, p-phenylene disulfide Alcohol, isophthalic acid, terephthalic acid, isophthalic acid, 2-mercaptobenzoic acid, 4-mercaptobenzoic acid, 4-aminobenzoic acid, 4-hydroxybenzoic acid, p-sulfobenzoic acid, p-nitrogen Benzoic acid, 4-mercaptoaniline, 4-hydroxyaniline, 4-cyanoaniline, 4-mercaptotylic acid, 4-hydroxystyrene acid, 2-(4- Phenyl)pyridine, 2-chloro-5-cyanothiazole, 2-amino-3-cyanothiophene, 1,5-diindenylnaphthalene, 1,5-dihydroxynaphthalene, 1,4-naphthalene dicarboxylic acid, 2,6-naphthalenedisulfonic acid, 3-amino-5-mercapto-1,2,4-triazole; and/or,

The replacement ligand is selected from the group consisting of 2,3-dimercaptosuccinic acid, 2,3-dihydroxysuccinic acid, pentaerythritol tetrakis(3-mercaptopropionic acid) ester, pentaerythritol tetraacrylate, pentaerythritol tetrabenzoate, Polydipentaerythritol pentaacrylate, tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] pentaerythritol ester, 3,5-dimethylhydrazine-2,6-diaminotoluene, 2 ,4-diamino-6-mercaptopyrimidine, 2-chloro-4-aminopyrimidine, dimethyl 2,3-dichlorosuccinate, diethyl 2,3-dichlorosuccinate, 1,2- Bis(4-aminophenoxy)ethane and poly(2,5-dodecanoyl-1,4-phenylacetylene-2-(11-hydroxyundecyloxycarbonyl)-1,4-benzene At least one of acetylene.
The method of preparing a quantum dot film according to claim 1, wherein during the gas phase ligand replacement, the internal pressure of the sealable device is from 10 -4 to 10 2 Pa, and the replacement ligand The partial pressure is 0.01 to 10 Pa; and / or,

The internal temperature of the sealable device is 5 to 200 ° C; and / or,

The gas phase ligand replacement time is from 0.5 to 360 min.
The method for preparing a quantum dot film according to claim 1, wherein the step of introducing a gaseous replacement ligand comprises: subjecting the liquid replacement ligand to evaporation or boiling treatment to obtain a gaseous replacement ligand, and then Passing into the closable device; or,

The solid replacement ligand is liquefied and then evaporated or directly subjected to sublimation treatment to obtain a gaseous replacement ligand, which is then introduced into the sealable device.
A quantum dot film characterized in that a surface ligand is attached to a surface of a quantum dot in the quantum dot film, and the surface ligand is an organic ligand containing at least two functional groups capable of binding to a surface of a quantum dot.
The quantum dot film according to claim 11, wherein the surface ligand is a conjugated ligand having the following chemical structural formula:

X 1 -RX 2

Wherein X 1 and X 2 are functional groups capable of bonding to the surface of the quantum dot; and R is a hydrocarbon group or a hydrocarbon derivative having a conjugated group.
The quantum dot film according to claim 12, wherein in the chemical structural formula of the surface ligand, X 1 and X 2 are independently selected from a halogen atom, a hydroxyl group, an ether group, a thiol group, a thioether group, and an aldehyde. Base, carbonyl, carboxyl, ester, nitro, nitroso, amino, imino, sulfo, acyl, nitroxyl, sulfonyl, cyano, isocyano, decyl, phosphino, phosphate, hydrazine At least one of a group, an epoxy group, an azo group, a vinyl group, an ethynyl group, an aromatic ring group; and/or,

The R includes at least one of a conjugated ring, -C=C-, -C≡C-, -C=O, -N=N-, -C≡N-, -C=N-; Or the R is a linear structure and/or a cyclic structure including alternating double bonds and single bonds.
The quantum dot film according to claim 11, wherein the surface ligand is a compound represented by the following formula I:

Where n is an integer greater than or equal to 1; when n=1, at least two of R1, R2, R3, R4, R1', R2', R3', R4' are compatible with quantum dots, or quantum dot surfaces Ligand-bound functional group; when n>1, at least one of R1, R2, R3, R4, R1', R2', R3', R4' is capable of binding to a quantum dot or a ligand on the surface of a quantum dot. Functional group.
The quantum dot film according to claim 14, wherein, in the compound of the formula I, n = 1-4; and/or

The functional groups in R1, R2, R3, R4, R1', R2', R3', R4' which can bind to quantum dots or ligands on the surface of quantum dots include: halogen atoms, hydroxyl groups, ether groups, mercapto groups, thioether groups. , aldehyde, carbonyl, carboxyl, ester, nitro, nitroso, amino, imino, thio, sulfo, acyl, amide, nitroxyl, sulfonyl, cyano, isocyano, fluorenyl At least one of a phosphino group, a phosphate group, a decyl group, an epoxy group, an azo group, a vinyl group, an ethynyl group, and an aromatic ring group.
A method for preparing a quantum dot light emitting diode, comprising the steps of:

Providing a bottom electrode;

Preparing a quantum dot preformed film on the bottom electrode, wherein the quantum dot surface of the quantum dot preformed film is bonded with an initial ligand;

The quantum dot pre-formed film is placed in a sealable device, and a gaseous replacement ligand is introduced to perform gas phase ligand replacement, thereby obtaining a quantum dot film having a quantum dot surface bonded to the replacement ligand to form a quantum dot light-emitting layer. Said replacement ligand contains at least one functional group capable of binding to the surface of the quantum dot;

Preparing a top electrode on the quantum dot luminescent layer;

Wherein the bottom electrode is an anode, the top electrode is a cathode; or the bottom electrode is a cathode, and the top electrode is an anode.
The method of preparing a quantum dot light emitting diode according to claim 16, wherein the bottom electrode is an anode and the top electrode is a cathode; and before the preparation of the quantum dot prefabricated film on the bottom electrode, a step of preparing a hole functional layer on the bottom electrode; and/or,

Before the preparation of the top electrode on the quantum dot light-emitting layer, the step of preparing an electronic functional layer on the quantum dot light-emitting layer is further included.
The method for preparing a quantum dot light emitting diode according to claim 16, wherein the bottom electrode is a cathode and the top electrode is an anode; before the preparation of the quantum dot prefabricated film on the bottom electrode, a step of preparing an electronic functional layer on the bottom electrode; and/or,

Before the preparation of the top electrode on the luminescent layer of the quantum dot, the step of preparing a hole functional layer on the quantum dot luminescent layer is further included.
The method for fabricating a quantum dot light emitting diode according to claim 16, wherein the quantum dot emitting layer is a light emitting layer, and the light emitting layer is combined to emit white light, and the step of preparing the light emitting layer stack comprises:

The quantum dot pre-formed film is placed in a sealable device, and a gaseous replacement ligand is introduced to perform gas phase ligand replacement to obtain a first quantum dot film in which a quantum dot surface is bonded to the replacement ligand, and the replacement is coordinated. The body is an organic ligand containing at least two functional groups capable of binding to the surface of the quantum dot;

The N-layer stacked quantum dot film is obtained by the preparation method of the first layer of quantum dot film to obtain a light-emitting laminate; or

The N-1 layer stacked quantum dot film is prepared by using the first layer quantum dot film preparation method, and an organic light emitting film is prepared on the N-1 layer quantum dot film to obtain a light emitting layer;

Where N is a positive integer and 2≤N≤10.
The method of preparing a quantum dot light-emitting diode according to claim 19, wherein in the N-layer stacked quantum dot film, 2 ≤ N ≤ 5; and/or

The thickness of the quantum dot film per layer is from 2 to 80 nm.