WO2024061105A1

WO2024061105A1 - Functional film and preparation method therefor, and light-emitting device

Info

Publication number: WO2024061105A1
Application number: PCT/CN2023/118874
Authority: WO
Inventors: 周礼宽; 杨一行
Original assignee: Tcl科技集团股份有限公司
Priority date: 2022-09-22
Filing date: 2023-09-14
Publication date: 2024-03-28
Also published as: CN117812926A

Abstract

A functional film and a preparation method therefor, and a light-emitting device (100). The functional film comprises quantum dots and metal cations connected to at least two adjacent quantum dots. The metal cations and first anions on the surfaces of the quantum dots form chemical bonds. Thus, the improvement of the fluorescence quantum yield (PLQY) of the quantum dots is facilitated; in addition, adjacent quantum dots are connected by means of the metal cations, thereby facilitating the improvement of the light-emitting efficiency and the service life of the device.

Description

Functional film and preparation method thereof and light-emitting device

This application claims priority to the Chinese patent application filed with the China Patent Office on September 22, 2022, with the application number 202211177931. The entire contents are incorporated herein by reference.

Technical field

The present application relates to the field of display devices, and in particular to a functional film, a preparation method thereof, and a light-emitting device.

Background technique

Quantum Dot Light-Emitting Diode (QLED, Quantum Dot Light-Emitting Diode) devices have the advantages of high luminous color purity, controllable color, high efficiency, good stability, and full solution processing. At present, common device structures of QLED include anode, quantum dots luminescent layer and cathode. The quantum dot luminescent layer includes quantum dots. There are a large number of dangling bonds on the surface of the quantum dots. The exposed dangling bonds will form defect states and defect energy levels in the energy band gap, causing non-radiative transition losses and reducing the luminous efficiency of the quantum dots.

technical problem

During the preparation process of quantum dot materials, organic ligands (such as long-chain carboxylic acid groups, amine groups and other organic compounds) are added to passivate the dangling bonds on the surface of quantum dots. However, these organic ligands are mostly anions and can only be partially passivated. The dangling bonds of metal cations on the quantum dot surface, and their charge-balanced cations show high solvation energy and low affinity to the quantum dot surface, such as hydrogen ions, alkali metal cations, NH ₃ ⁺ or N ₂ H ₅ ⁺ , etc. , unable to passivate the anionic dangling bonds on the quantum dot surface. Unpassivated anionic dangling bonds have a greater impact on the luminous efficiency or lifetime of the device.

Technical solutions

This application proposes a functional film, which includes quantum dots and metal cations connecting at least two adjacent quantum dots. The metal cations form chemical bonds with the first anions on the surface of the quantum dots.

Optionally, in some embodiments of the present application, the functional film is composed of the quantum dots and the metal cations connecting at least two adjacent quantum dots.

Optionally, in some embodiments of the present application, the metal cations include at least one of divalent metal cations and trivalent metal cations.

Optionally, in some embodiments of the present application, the atomic percentage of the metal cations in the functional film is 0.1 to 5%; and/or,

In the functional film, the quantum dots with the metal cations connected to their surfaces are first quantum dots, and the hydrated particle size of the first quantum dots is 20 to 50 nm.

Optionally, in some embodiments of the present application, the divalent metal cations include Cd ²⁺ , Zn ²⁺ , Ca ²⁺ , Mn ²⁺ , Pt ²⁺ , Cu ²⁺ , Co ²⁺ and Fe ^{2 +} , and the trivalent metal cation includes at least one of Al ³⁺ , Fe ³⁺ , Ni ³⁺ , Cr ³⁺ and In ³⁺ .

This application also provides a method for preparing a functional membrane, which includes the following steps:

Provide a treatment liquid and a quantum dot film, the treatment liquid containing metal cations;

The treatment liquid is brought into contact with the surface of the quantum dot film, so that adjacent quantum dots in the quantum dot film are connected to each other through the metal cations to obtain a functional film.

Optionally, in some embodiments of the present application, the metal cations include at least one of divalent metal cations and trivalent metal cations; and/or,

The treatment liquid also contains a second anion, and the second anion includes at least one of nitrate ions, sulfate ions, sulfonate ions and perchlorate ions; and/or,

The time for contacting the treatment liquid with the surface of the quantum dot film is 5-30 seconds.

Optionally, in some embodiments of the present application, the divalent metal cation includes at least one of Cd ²⁺ , Zn ²⁺ , Ca ²⁺ , Mn ²⁺ , Pt ²⁺ , Cu ²⁺ , Co ²⁺ and Fe ²⁺ , and the trivalent metal cation includes at least one of Al ³⁺ , Fe ³⁺ , Ni ³⁺ , Cr ³⁺ and In ³⁺ .

Optionally, in some embodiments of the present application, the treatment liquid is brought into contact with the surface of the quantum dot film, so that adjacent quantum dots in the quantum dot film are connected to each other through the metal cations, The steps to obtain functional membranes include:

The treatment liquid is placed on the surface of the quantum dot film to form a liquid film, and after standing, the liquid film is removed to obtain a functional film; or,

The quantum dot film is placed in the treatment liquid, so that at least one surface of the quantum dot film is in contact with the treatment liquid, and after standing, the quantum dot film is taken out, and the surface of the quantum dot film is removed. Treat the liquid to obtain a functional membrane.

Optionally, in some embodiments of the present application, the treatment liquid is placed on the quantum dot The method of forming a liquid film on the surface of the film includes: using a treatment solution with a concentration of 2-5 mg/mL to repeatedly coat the surface of the quantum dot film multiple times to form a liquid film; or,

The method of arranging the treatment liquid on the surface of the quantum dot film to form a liquid film includes: using a treatment liquid with a concentration of 5-50 mg/mL to coat the surface of the quantum dot film once to form a liquid film. membrane.

Optionally, in some embodiments of the present application, the quantum dot film is placed in the treatment liquid, so that at least one surface of the quantum dot film is in contact with the treatment liquid, and then the quantum dot film is removed after standing. In the step of removing the treatment liquid on the surface of the quantum dot film to obtain a functional film, the concentration of the treatment liquid is 5-50 mg/mL.

This application also provides a light-emitting device. The light-emitting device includes a stacked anode, a light-emitting layer, and a cathode. The light-emitting layer includes a functional film. The functional film includes the functional film as described above, or the functional film Prepared by the preparation method as described above.

Optionally, in some embodiments of the present application, the quantum dots of the functional film are selected from one or more of single structure quantum dots and core-shell structure quantum dots, and the material of the single structure quantum dot is selected from At least one of Group II-VI compounds, Group IV-VI compounds, Group III-V compounds and Group I-III-VI compounds, wherein the Group II-VI compounds are selected from the group consisting of CdS, CdSe, CdTe, ZnS, C dZnSeS, At least one of CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, the IV-VI compound is selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, At least one of PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe and SnPbSTe, the III-V compound is selected from the group consisting of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, At least one of GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs or InAlPSb, the I-III-VI group compound is selected from at least one of CuInS ₂ , CuInSe ₂ and AgInS ₂ , and the core-shell structure The core of the quantum dot includes any one of the above single structure quantum dots, and the shell material of the quantum dot of the core-shell structure includes CdS, CdTe, CdSeTe, CdZnSe, CdZnS, CdSeS, ZnSe, ZnSeS, ZnS and at least one of the above single structure quantum dots; and/or,

The anode and the cathode are independently selected from metal electrodes, carbon material electrodes, metal oxide electrodes or composite electrodes, and the material of the metal electrode is selected from the group consisting of Ag, Al, Mg, Au, Cu, Mo, Yb, Ca and at least one of Ba, the material of the carbon material electrode is selected from at least one of graphite, carbon nanotubes, graphene and carbon fiber, the material of the metal oxide electrode is selected from ITO, FTO, ATO, AZO , at least one of GZO, IZO, MZO and AMO, the composite electrode is selected from AZO/Ag/AZO, AZO/Al/AZO, ITO/Ag/ITO, ITO/Al/ITO, ZnO/Ag/ZnO, At least one of ZnO/Al/ZnO, TiO ₂ /Ag/TiO ₂ , TiO ₂ /Al/TiO ₂ , ZnS/Ag/ZnS, and ZnS/Al/ZnS.

Optionally, in some embodiments of the present application, the light-emitting device further includes a hole function layer provided between the anode and the light-emitting layer, the hole function layer includes a hole transport layer and/or Or a hole injection layer, the materials of the hole transport layer and the hole injection layer are independently selected from TFB, CuPc, PVK, Poly-TPD, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD, PEDOT: PSS, TAPC, MCC, F4-TCNQ, HATCN, 4,4',4'-tris(N-3-methylphenyl-Nphenylamino)triphenylamine, polyaniline, transition metal oxides, transition At least one of metal sulfide, transition metal tinide, doped graphene, non-doped graphene and C60; and/or,

The light-emitting device further includes an electronic functional layer provided between the cathode and the light-emitting layer. The electronic functional layer includes an electron transport layer and/or an electron injection layer. The electron transport layer and/or the electron injection layer The material of the injection layer includes inorganic materials and/or organic materials. The inorganic materials are selected from doped or non-doped metal oxides. The metal oxides include zinc oxide, barium oxide, aluminum oxide, nickel oxide, and titanium oxide. , tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanium oxide, zinc aluminum oxide, zinc manganese oxide, zinc tin oxide, lithium zinc oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, sulfide One or more of copper, zinc tin, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, and barium titanate. The doped elements include aluminum, magnesium, lithium, manganese, yttrium, lanthanum, One or more of copper, nickel, zirconium, cerium, and gadolinium. The organic material is selected from quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, and hydroxyquinoline compounds. or more.

In addition, this application also proposes a display device, which includes the light-emitting device as described above.

beneficial effects

Compared with the prior art, this application provides a functional film containing quantum dots, adjacent quantum dots are connected through metal cations, and the metal cations form chemical bonds with the first anions on the surface of the quantum dots, thereby suspending the anions on the surface of the quantum dots. It plays a passivation role, reducing defect states on the surface of quantum dots, eliminating non-radiative channels introduced by defect states, which is beneficial to improving the fluorescence quantum yield (PLQY) of quantum dots; at the same time, because adjacent quantum dots are connected through metal cations Together, the functional film is made denser, the coupling effect is enhanced, and the carrier transmission speed is increased, thereby obtaining a higher exciton density, which is beneficial to improving the luminous efficiency or lifetime of the device.

Description of the drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, other drawings can also be obtained based on these drawings without exerting creative efforts.

Figure 1 is a schematic flow chart of a method for preparing a functional film provided by the first embodiment of the present application;

Figure 2 is a schematic flow chart of a method for preparing a functional film provided in the second embodiment of the present application;

FIG3 is a schematic flow chart of a method for preparing a functional film provided in a third embodiment of the present application;

Figure 4 is a schematic flow chart of a method for preparing a functional film provided by the fourth embodiment of the present application;

Figure 5 is a schematic flow chart of a method for preparing a device provided in Embodiment 1 of the present application;

Figure 6 is a schematic structural diagram of a light-emitting device provided by an embodiment of the present application;

FIG. 7 is a schematic structural diagram of a light-emitting device provided by another embodiment of the present application.

Reference signs:
100-Light-emitting device; 10-Anode; 20-Light-emitting layer; 30-Electron transport layer; 40-Cathode; 50-Hole transport layer; 60-Hole injection layer.

Implementation Mode of this Application

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without any creative work shall fall within the scope of protection of this application. In addition, it should It is understood that the specific implementations described here are only used to illustrate and explain the present application, and are not used to limit the present application. In this application, unless otherwise specified, the directional words used such as "upper" and "lower" specifically refer to the direction of the drawing in the drawings. In addition, in the description of this application specification, the term "including" means "including but not limited to". Various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and simplicity and should not be understood as a hard limit to the scope of the present application; therefore, the described scope should be considered The description has specifically disclosed all possible subranges as well as the single numerical values within that range. For example, a description of a range from 1 to 6 should be considered to have specifically disclosed subranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and A single number within the stated range, such as 1, 2, 3, 4, 5, and 6, applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it is intended to include any cited number (fractional or whole) within the indicated range.

In this application, "and/or" describes the association of associated objects, indicating that there can be three relationships, for example, A and/or B, which can mean: A exists alone, A and B exist simultaneously, and B exists alone. Condition. Where A and B can be singular or plural.

In this application, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions thereof refers to any combination of these items, including any combination of a single item (items) or a plurality of items (items). For example, "at least one of a, b, or c", or "at least one of a, b, and c" can mean: a, b, c, a-b ( That is, a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple respectively.

There are some unpassivated anionic dangling bonds on the surface of the quantum dots. For the convenience of description, in this article, the anions on the surface of the quantum dots are defined as the first anions. Based on the specific material of the quantum dot, the first anion can be a sulfur anion, a tellurium anion, a selenium anion, etc. Taking the core-shell structure quantum dot material CdZnSe/ZnSeS/ZnS as an example, the outermost shell is ZnS, and the surface of the quantum dot There are partially unpassivated sulfide anions, ie, in this example, the first anion is a sulfide anion. In the technical solution provided by this application, a functional film is provided. Among the multiple quantum dots it contains, adjacent quantum dots are connected through metal cations. The metal cations form chemical bonds with the first anions on the surface of the quantum dots, thereby affecting the quantum dots. The anionic dangling bonds on the surface play a passivation role, reducing the defect states on the surface of the quantum dots and eliminating them. The introduced non-radiative channel is beneficial to improving the fluorescence quantum yield (PLQY) of quantum dots; at the same time, because adjacent quantum dots are connected through metal cations, the functional film is made denser, the coupling effect is enhanced, and the current carrying capacity is improved. The exciton transmission speed is increased, thereby obtaining a higher exciton density, which is beneficial to improving the luminous efficiency and lifetime of the device.

In a specific embodiment, the functional film is composed of the quantum dots and the metal cations connecting at least two adjacent quantum dots.

Specifically, the metal cations include at least one of divalent metal cations and trivalent metal cations. Divalent metal cations can connect two adjacent quantum dots, and trivalent metal cations can connect three adjacent quantum dots. The divalent metal cations can be selected from any one or more divalent metal cations. For example, the divalent metal cations can include but are not limited to Cd ²⁺ , Zn ²⁺ , Ca ²⁺ , Mn ²⁺ , at least one of Pt ²⁺ , Cu ²⁺ , Co ²⁺ and Fe ²⁺ ; the trivalent metal cation can be selected from any one or more metal cations with a trivalent valence state, for example, trivalent metal cations It may include but is not limited to at least one of Al ³⁺ , Fe ³⁺ , Ni ³⁺ , Cr ³⁺ and In ³⁺ .

The quantum dots may be one of red quantum dots, green quantum dots and blue quantum dots. The quantum dots are selected from one or more of single structure quantum dots and core-shell structure quantum dots. The materials of the single structure quantum dots are selected from the group consisting of II-VI compounds, IV-VI compounds, III-V compounds and At least one of the compounds of Group I-III-VI, wherein the compound of Group II-VI is selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgST e. At least one of HgZnSeS, HgZnSeTe and HgZnSTe One, the IV-VI group compound is selected from at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe and SnPbSTe One, the III-V group compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, At least one of AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs or InAlPSb , the I-III-VI group compound is selected from at least one of CuInS ₂ , CuInSe ₂ and AgInS ₂ , and the core of the quantum dot of the core-shell structure includes the above-mentioned single structure. Constituting any one of the quantum dots, the shell material of the core-shell structure quantum dots includes at least one of CdS, CdTe, CdSeTe, CdZnSe, CdZnS, CdSeS, ZnSe, ZnSeS, ZnS and the above single structure quantum dots . The quantum dots also contain metal cations. To facilitate distinction, the metal cations connecting adjacent quantum dots are defined as first metal cations, and all metal cations in the quantum dots are defined as second metal cations.

In some embodiments of the present application, in the functional film, the atomic percentage of the first metal cation is 0.1-5%, for example, the atomic percentage of the first metal cation can be 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.5%, 2%, 3%, 5%, and values within the range between any two of the above values. The atomic percentage described in the present application refers to the percentage of the number of atoms of the first metal cation to the total number of all atoms in the functional film.

In some embodiments of the present application, the functional film contains a plurality of quantum dots, wherein at least part of the surface of the quantum dots is connected to the metal cation. Herein, this surface is connected to the metal cation. Quantum dots are defined as first quantum dots, and other quantum dots that are not connected to the metal cation are defined as second quantum dots. The hydrated particle size of the first quantum dot is 20-50 nm. The hydrated particle size reflects the comprehensive particle size of the quantum dots in the solution state. In this application, the hydrated particle size range of the first quantum dot may be 20-30nm, 23-35nm, 25-38nm, 30-40nm, 35-40nm, 39-45nm, 42-50nm, etc.

The embodiments of the present application provide a method for preparing a functional film. Figures 1 to 4 are specific examples of the method for preparing the functional film.

Referring to Figure 1, the preparation method of the functional film includes the following steps:

Step S10: Provide a treatment liquid and a quantum dot film, where the treatment liquid contains metal cations.

In step S20, the treatment liquid is brought into contact with the surface of the quantum dot film, so that adjacent quantum dots in the quantum dot film are connected to each other through the metal cations to obtain a functional film.

The quantum dot film described in this application refers to a film formed on a substrate using quantum dot luminescent materials. It can be specifically achieved using conventional techniques in the art, for example, chemical methods or physical methods. Chemical methods include chemical vapor deposition, continuous ion layer adsorption and reaction, anodizing, electrolytic deposition, and co-precipitation. Physical methods include physical coating methods and solution methods. Physical coating methods include: thermal evaporation coating method, electron beam evaporation coating method, magnetron sputtering method, multi-arc ion coating method, physical vapor deposition method, atomic layer deposition method, pulse laser Deposition method, etc.; solution method can be spin coating, printing, inkjet printing, scraping method, printing method, dipping and pulling method, soaking method, spray coating method, roller coating method, casting method, slit coating method and strip coating method, etc.

In this application, a treatment solution containing metal cations is used to surface treat the quantum dot film. The metal cations can passivate the anionic dangling bonds on the surface of the quantum dots, thereby reducing the defect states on the surface of the quantum dots and eliminating defects caused by the defect states. Shallow traps and deep traps improve carrier transport capabilities and eliminate some fast non-radiative channels introduced by defect states, which is beneficial to improving the fluorescence quantum yield (PLQY) of quantum dots and enabling devices to obtain higher currents. efficiency and lifetime stability.

On the other hand, this application uses a treatment solution to treat the surface of the quantum dot film after the quantum dot film is formed. Metal cations can serve as bridging ligands to connect adjacent quantum dots, making the quantum dot film denser and enhancing coupling. effect, which is conducive to increasing the carrier transmission speed. In comparison, if the treatment liquid is added during the film preparation stage, the problem of agglomeration in the liquid phase will occur due to quantum dot bridging, which will affect subsequent film preparation.

In step S10, the metal cation may be selected from, but is not limited to, at least one of divalent metal cations and trivalent metal cations. Wherein, the divalent metal cation can be selected from but not limited to Mg ²⁺ , Pd ²⁺ , Cd ²⁺ , Zn ²⁺ , Ca ²⁺ , Mn ²⁺ , Pt ²⁺ , Cu ²⁺ , Co ²⁺ and At least one of Fe ²⁺ . The trivalent metal cation may be selected from, but is not limited to, at least one of Al ³⁺ , Fe ³⁺ , Ni ³⁺ , Cr ³⁺ , and In ³⁺ . The above-mentioned metal cations help passivate the anions on the quantum dot surface into bonds to form fewer lattice defects.

It can be understood that the treatment liquid may contain one or more metal cations, for example, it may contain two or more divalent cations, or it may contain both divalent cations and trivalent cations. In some embodiments, there is only one type of metal cation contained in the treatment liquid. The type mentioned here refers to the same type of element and the same valence state. In at least one embodiment, the metal cation includes one of Cd ²⁺ , Zn ²⁺ , Ca ²⁺ , Mn ²⁺ , Pt ²⁺ , Al ³⁺ and In ³⁺ . Relatively speaking, when the treatment solution contains only one kind of metal cation, the functional film can achieve short-range and long-range ordering, which helps to improve device performance.

In step S10, the treatment liquid also contains anions, which mainly cooperate with metal cations to achieve charge balance. For convenience of description and distinction, this anion is defined as the second anion in this article. Since the role of the second anion is to cooperate with the metal cation to achieve charge balance, the second anion can be any anion that can cooperate with the cation to form a soluble salt. Further, the second anion may be an anion with low affinity to the quantum dot surface, for example, at least one of nitrate ions, sulfate ions, sulfonate ions, and perchlorate ions. Compared with halide ions, etc., the above-mentioned Select organic ligands that will not affect the surface connection of quantum dots to avoid increasing surface defect states and affecting the luminous efficiency and lifetime of the device.

The solvent in the treatment liquid includes an alcohol phase solvent, and the alcohol phase solvent can be selected from, but is not limited to, at least one of methanol, ethanol, isopropyl alcohol, and butanol.

In step S10, the quantum dot film can be a film made of any quantum dot luminescent material known in the art for use in the quantum dot luminescent layer. The quantum dots may be one of red quantum dots, green quantum dots and blue quantum dots. The quantum dots are selected from one or more of single structure quantum dots and core-shell structure quantum dots. The materials of the single structure quantum dots are selected from the group consisting of II-VI compounds, IV-VI compounds, III-V compounds and At least one of the compounds of Group I-III-VI, wherein the compound of Group II-VI is selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgST e. At least one of HgZnSeS, HgZnSeTe and HgZnSTe One, the IV-VI group compound is selected from at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe and SnPbSTe One, the III-V group compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, At least one of AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs or InAlPSb , the I-III-VI group compound is selected from at least one of CuInS ₂ , CuInSe ₂ and AgInS ₂ , the core of the core-shell structure quantum dots includes any one of the above single structure quantum dots, the The shell material of the core-shell structure quantum dots includes at least one of CdS, CdTe, CdSeTe, CdZnSe, CdZnS, CdSeS, ZnSe, ZnSeS, ZnS and the above single structure quantum dots.

In some embodiments of the present application, the contact time for bringing the treatment liquid into contact with the surface of the quantum dot film in step S20 is further limited. Specifically, the contact time may be 5-30 s, for example, The contact time can be 5s, 6s, 7s, 8s, 10s, 12s, 15s, 17s, 18s, 20s, 22s, 25s, 26s, 28s, 30s and values within the range between any two of the above values, etc. Controlling the contact time within this range helps ensure that the anionic dangling bonds on the surface of the quantum dots are fully passivated and ensures effective bridging between quantum dots.

In addition, in step S20, there are many ways to bring the treatment liquid into contact with the surface of the quantum dot film. For example, the treatment liquid is placed on the surface of the quantum dot film through a solution method, or the quantum dot film is soaked. in the treatment fluid, etc. Among them, the solution method can be coating method, printing method, inkjet printing method, blade coating method, printing method, dip pulling method, soaking method, spray coating method, roller coating method, casting method, slit coating method and Strip coating method, etc. By contacting the surface of the quantum dot film, the treatment liquid achieves cationic passivation of the surface of the quantum dot film and bridges the quantum dots.

Specifically, in some embodiments of the present application, as shown in Figures 2 and 3, step S20 can be implemented as follows:

Step S21: The treatment liquid is placed on the surface of the quantum dot film to form a liquid film. After standing, the liquid film is removed to obtain a functional film.

When a contact method of forming a liquid film on the surface of the quantum dot film is adopted, the concentration of the treatment liquid used can be 2-50 mg/mL, for example, 2 mg/mL, 3 mg/mL, 4 mg/mL, 5 mg/mL, 6 mg/mL, 8 mg/mL, 10 mg/mL, 15 mg/mL, 20 mg/mL, 25 mg/mL, 30 mg/mL, 35 mg/mL, 40 mg/mL, 45 mg/mL, 50 mg/mL and values within the range between any two of the above values, etc. Using a treatment liquid in this range to treat the quantum dot film can achieve effective connection between quantum dots, and make its surface fully passivated, effectively reducing its surface defects.

In actual processing, the solution method can be used to coat the surface of the quantum dot film with a treatment liquid to form a liquid film. This not only has high processing efficiency, but also the thickness of the formed liquid film is uniform and controllable, which helps to make the surface of the quantum dot film various. Everywhere is evenly modified. Specifically, scraping or spin coating can be used. Taking spin coating as an example, this application does not limit the specific rotation speed during spin coating. During implementation, the spin coating speed is subject to being able to form a film to cover the surface of the quantum dot film to achieve ligand exchange. As an example, the rotation speed during spin coating is It can be set to 1000-5000rpm, for example, 1000rpm, 2000rpm, 3000rpm, 4000rpm, 5000rpm, and values within the range between any two of the above values. In this way, it can ensure the spreadability while ensuring the formation of a single layer of liquid. The film has a certain thickness to provide a sufficient amount of cations so that the surface of the quantum dots can be fully modified. It is understood that the rotation speed of spin coating can also be set higher, but accordingly, the number of spin coatings can be increased to ensure that the amount of cations contained in the formed multi-layer liquid film is sufficient to fully modify the surface of the quantum dot film it covers.

In an embodiment, step S21 may be performed as follows:

Step S21a: Use a treatment liquid with a concentration of 5-50 mg/mL to coat the surface of the quantum dot film once to form a liquid film.

Using a one-time coating method with a higher concentration of treatment solution can fully modify the film surface while preventing the liquid film from covering the film surface for too long, thereby preventing the solvent from penetrating into the film and causing an increase in quantum dot surface defects. In actual operation, the concentration of the treatment solution can be 5mg/mL, 6mg/mL, 8mg/mL, 10mg/mL, 15mg/mL, 20mg/mL, 25mg/mL, 30mg/mL, 35mg/mL, 40mg/mL, 45mg/mL, 50mg/mL, and values within the range between any two of the above values, etc.

Further, in step S21a, after forming the liquid film, let it stand for 5-30 seconds and then remove the liquid film to ensure that adjacent quantum dots in the quantum dot film can be connected to each other through metal cations. Among them, the resting time can be 5s, 6s, 7s, 8s, 10s, 12s, 15s, 17s, 18s, 20s, 22s, 25s, 26s, 28s, 30s and any value in the range between any two of the above values. wait.

In another embodiment, step S21 may be performed as follows:

Step S21b: Use a treatment liquid with a concentration of 2-5 mg/mL to coat the surface of the quantum dot film multiple times to form a liquid film. In actual operation, the concentration of the treatment solution can be 2mg/mL, 2.5mg/mL, 3mg/mL, 3.5mg/mL, 4mg/mL, 4.5mg/mL, 5mg/mL, or between any two of the above values. Values within the range, etc.

The use of multiple coatings of a lower concentration treatment solution can ensure that the film surface is fully modified while preventing the liquid film from covering the film surface for too long, thus preventing the solvent from penetrating into the film and causing an increase in quantum dot surface defects.

Further, in step S21b, after forming the liquid film, let it stand for 5-30 seconds and then remove the liquid film to ensure that adjacent quantum dots in the quantum dot film can be connected to each other through metal cations. Among them, the resting time can be 5s, 6s, 7s, 8s, 10s, 12s, 15s, 17s, 18s, 20s, 22s, 25s, 26s, 28s, 30s and any value in the range between any two of the above values. wait.

In some embodiments, the method for removing the liquid film may be washing, soaking, spin coating, centrifugation, etc. In the embodiment of the present application, the treatment liquid uses an alcohol phase solvent as the solvent of the metal salt. Based on this, in step S21, the treatment liquid is contacted with the surface of the quantum dot film for a period of time so that the surface is fully modified. , alcohol-phase solvents, such as methanol, ethanol, butanol, isopropyl alcohol, etc., can be used to clean the film surface to remove the liquid film.

In some embodiments of the present application, referring to Figure 4, step S20 can also be implemented as follows:

Step S22: Place the quantum dot film in the treatment liquid, bring at least one surface of the quantum dot film into contact with the treatment liquid, take out the quantum dot film after standing, and remove the quantum dots. Treatment liquid on the surface of the film to obtain a functional film.

In the method of this embodiment, the quantum dot film is soaked or covered in the treatment liquid, so that one or both sides of the quantum dot film can fully contact the treatment liquid, so that its surface can be fully modified by metal cations. The contact time can be 5-30s, for example, it can be 5s, 6s, 7s, 8s, 10s, 12s, 15s, 17s, 18s, 20s, 22s, 25s, 26s, 28s, 30s, and any two of the above values. Values within the range, etc.

Further, in step S22, the concentration of the treatment liquid is 5-50 mg/mL, for example, 5 mg/mL, 6 mg/mL, 8 mg/mL, 10 mg/mL, 15 mg/mL, 20 mg/mL, 25 mg/mL, 30mg/mL, 35mg/mL, 40mg/mL, 45mg/mL, 50mg/mL and values within the range between any two of the above values, etc., while ensuring that the film surface of the same area is fully modified, Using a higher concentration (5-50 mg/mL) treatment solution requires shorter time to treat the film and avoids solvent penetration into the film.

In some embodiments, the method for removing the treatment liquid on the surface of the quantum dot film may be washing, coating, centrifugation, etc.

In the surface treatment method of the embodiment of the present application, the treatment liquid uses an alcohol phase solvent as the solvent of the metal salt. Based on this, in step S22, the treatment liquid is contacted with the surface of the quantum dot film for a period of time, so that the surface of the quantum dot film is After being fully modified, alcohol-phase solvents, such as methanol, ethanol, butanol, isopropyl alcohol, etc., can be used to clean the film surface to remove the treatment solution on the surface of the quantum dot film.

The embodiment of the present application also provides a light-emitting device 100. Refer to Figure 6. The light-emitting device 100 includes a stacked anode 10, a light-emitting layer 20 and a cathode 40. The light-emitting layer 20 includes a functional film, and the functional film includes the above-mentioned A functional film, or the functional film is prepared by the preparation method as described above.

The quantum dots of the functional film are selected from one or more of single structure quantum dots and core-shell structure quantum dots, and the materials of the single structure quantum dots are selected from II-VI compounds, IV-VI compounds, III -At least one of Group V compounds and Group I-III-VI compounds, wherein the Group II-VI compound is selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS , CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, At least one of CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, the IV-VI compound is selected from S nS, At least one of SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe and SnPbSTe, and the III-V compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, At least one of InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs or InAlPSb, and the Group I-III-VI compound is selected from CuInS ₂ , CuInSe ₂ and AgInS ₂ , the core of the quantum dots of the core-shell structure includes any one of the above single structure quantum dots, and the shell material of the quantum dots of the core-shell structure includes CdS, CdTe , CdSeTe, CdZnSe, CdZnS, CdSeS, ZnSe, ZnSeS, ZnS and at least one of the above single structure quantum dots.

Because the quantum dots in the above functional film have high fluorescence quantum efficiency, the light-emitting device 100 has high luminous efficiency and lifespan; at the same time, because the film itself has a strong coupling effect, it is conducive to carrier transmission, thereby conducive to improving The carrier mobility of the light-emitting device 100 obtains a higher exciton density in the light-emitting layer 20 and improves the luminous efficiency and life of the device.

The light-emitting layer 20 may have a single film layer structure composed of a single layer of functional films, or may have a composite film layer structure composed of multiple layers of functional films. When the luminescent layer 20 is configured as a multi-layer structure, each film layer can be configured as the functional film, which helps to further improve the luminous efficiency and lifespan of the device including the luminescent layer 20 .

The light-emitting device 100 includes but is not limited to a quantum dot light-emitting diode. During actual processing, the above-mentioned light-emitting device 100 can be prepared using a quantum dot light-emitting diode preparation method known in the art.

The materials of cathode 40 and anode 10 may be any known in the art. The materials of the anode 10 and the cathode 40 may be, for example, one or more of metals, carbon materials, and metal oxides. The metal can be, for example, one or more of Ag, Al, Mg, Au, Cu, Mo, Yb, Ca, and Ba; the carbon material can be, for example, one or more of graphite, carbon nanotubes, graphene, and carbon fiber. species; the metal oxide can be doped or undoped metal oxide, including indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium doped zinc oxide (GZO), indium doped oxide One or more of zinc (IZO), magnesium-doped zinc oxide (MZO) and aluminum-doped magnesium oxide (AMO). In addition, the anode 10 and the cathode 40 may also include composite electrodes with metal sandwiched between doped or undoped transparent metal oxides. The composite electrodes may be, for example, AZO/Ag/AZO, AZO/Al/AZO, ITO/Ag/ITO, ITO/Al/ITO, ZnO/Ag/ZnO, ZnO/Al/ZnO, TiO ₂ /Ag/TiO ₂ , TiO ₂ /Al/TiO ₂ , ZnS/Ag/ZnS, ZnS/Al/ ZnS etc.

Those skilled in the art can understand that, as shown in FIG. 7 , the light-emitting device 100 may also include an electronic functional layer disposed between the cathode 40 and the light-emitting layer 20 . The electronic functional layer may be the electron transport layer 30 or the electronic functional layer 30 . The injection layer may also be an electron injection layer and an electron transport layer 30. When the electron functional layer is a stacked electron injection layer and electron transport layer 30, the cathode 40, the electron injection layer, the electron transport layer 30 and the light emitting layer 20 are stacked in sequence. The electron transport layer 30 and/or the electron injection layer are made of materials including inorganic materials and/or organic materials. The inorganic materials are selected from doped or undoped metal oxides, and the metal oxides include zinc oxide. , barium oxide, aluminum oxide, nickel oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanium oxide, aluminum zinc oxide, zinc manganese oxide, zinc tin oxide, lithium zinc oxide, indium tin oxide, sulfide One or more of cadmium, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc tin, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, and barium titanate. The doped elements include One or more of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium, and the organic material is selected from quinoxaline compounds, imidazole compounds, and triazine compounds, containing One or more of fluorene compounds and hydroxyquinoline compounds.

Those skilled in the art can understand that, as shown in FIG. 7 , the light-emitting device 100 may further include a hole injection layer 60 and a hole transport layer 50 disposed in sequence between the anode 10 and the light-emitting layer 20 .

The material of the hole transport layer 50 can be selected from organic materials with hole transport capabilities, including but not limited to TFB, CuPc, PVK, Poly-TPD, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD, PEDOT: PSS, TAPC, MCC, F4-TCNQ, HATCN, 4,4',4'-tris(N-3-methylphenyl-Nphenylamino)triphenylamine, polyaniline, transition metal oxides, transition metal sulfide At least one of material, transition metal tin compound, doped graphene, non-doped graphene and C60.

The material of the hole injection layer 60 is a material known in the art for the hole injection layer 60, including but not limited to TFB, CuPc, PVK, Poly-TPD, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD , PEDOT: PSS, TAPC, MCC, F4-TCNQ, HATCN, 4,4',4'-tris(N-3-methylphenyl-Nphenylamino)triphenylamine, polyaniline, transition metal oxides, At least one of transition metal sulfide, transition metal tinide, doped graphene, non-doped graphene and C60.

The method of forming the light-emitting layer 20 and other functional layers such as the hole injection layer 60, the hole transport layer 50 and the electron transport layer 30 may be chemical or physical. Among them, the chemical method can be chemical vapor deposition method, continuous ion layer adsorption and reaction method, anodizing method, electrolytic deposition method, co-precipitation method, etc. The physical method can be physical coating method or solution processing method. The physical coating method can be thermal evaporation coating method CVD, electron beam evaporation coating method, magnetron sputtering method, multi-arc ion coating method, physical vapor deposition method PVD, atomic layer deposition. method and pulse laser deposition method, etc.; the solution processing method can be spin coating method, printing method, inkjet printing method, scraping method, printing method, dip pulling method, soaking method, spray coating method, roller coating method, casting method, Slit coating method and strip coating method, etc. Those skilled in the art can prepare each film layer of the light-emitting device 100 in the embodiment of the present application according to the manufacturing methods of light-emitting devices commonly known in the art, and details will not be described again here.

The technical solutions and technical effects of the present application will be described in detail below through specific examples, comparative examples and experimental examples. The following examples are only some examples of the present application and do not specifically limit the present application.

Example 1

Preparation of quantum dot film:

(1) A luminescent material solution is provided, wherein the luminescent material in the luminescent material solution is red quantum dots CdZnSe/ZnSeS/ZnS, the solvent is n-octane, and the concentration of the luminescent material solution is 10 mg/mL. Then, the luminescent material solution is spin-coated on quartz glass at a speed of 2000 rpm to obtain a quantum dot film.

(2) Use 10 mg/ml cadmium nitrate ethanol solution to spin-coat the quantum dot film once at 2000 rpm to form a liquid film. After 10 seconds, spin-coat the liquid film with ethanol to clean the surface of the quantum dot film. Obtain functional membrane.

Device preparation:

This embodiment provides a QLED device. The structure of the QLED device is: substrate/QLED anode/hole injection layer/hole transport layer/light-emitting layer/electron transport layer/QLED cathode.

Referring to Figure 5, the method of preparing the device includes the following steps:

S101: Provide glass substrate.

S102: Prepare an ITO film with a thickness of 100 nm on the glass substrate by magnetron sputtering to form the anode 10.

S103: Spin-coat PEDOT:PSS material on the anode 10 to obtain a hole injection layer 60 with a thickness of 50 nm.

S104: Spin-coat the TFB material on the hole injection layer 60 to obtain the hole transport layer 50 with a thickness of 30 nm.

S105: Spin-coat the luminescent material solution on the hole transport layer 50 to obtain a quantum dot film with a thickness of 20 nm, wherein the luminescent material in the luminescent material solution is red quantum dots CdZnSe/ZnSeS/ZnS, and the solvent is positive Octane, the concentration of the luminescent material solution is 15 mg/mL. Then, use an ethanol solution of 10 mg/ml cadmium nitrate to spin-coat (2000 rpm) on the quantum dot film to form a film. After 10 seconds, spin-coat the quantum dot film with ethanol to clean the quantum dot film to obtain the luminescent layer 20 .

S106: Spin-coat ZnO material on the light-emitting layer 20 to obtain an electron transport layer 30 with a thickness of 30 nm.

S107: Evaporate Ag on the electron transport layer 30 to obtain a cathode 40 with a thickness of 100 nm, and obtain a light-emitting diode.

Example 2

This embodiment is basically the same as Embodiment 1. The only difference from Embodiment 1 is that in this embodiment:

The ethanol solution of cadmium nitrate was changed to the ethanol solution of calcium nitrate.

Example 3

This embodiment is basically the same as Embodiment 1, and the only difference from Embodiment 1 is that in this embodiment:

The ethanol solution of cadmium nitrate was changed to the ethanol solution of aluminum nitrate.

Example 4

The ethanol solution of cadmium nitrate was changed to the ethanol solution of indium nitrate.

Example 5

The ethanol solution of cadmium nitrate was changed to the ethanol solution of manganese nitrate.

Example 6

The ethanol solution of cadmium nitrate was changed to the ethanol solution of platinum nitrate.

Example 7

The ethanol solution of cadmium nitrate was changed to the ethanol solution of zinc nitrate.

Example 8

The ethanol solution of cadmium nitrate was changed to the ethanol solution of copper nitrate.

Example 9

The ethanol solution of cadmium nitrate was changed to the ethanol solution of iron nitrate.

Example 10

The ethanol solution of cadmium nitrate was changed to the ethanol solution of nickel nitrate.

Example 11

The ethanol solution of 10 mg/ml cadmium nitrate was changed to the ethanol solution with a concentration of 2 mg/mL manganese sulfate. When forming a liquid film, the number of spin coatings was changed from 1 to 5 times. After the liquid film was formed, the standing time was changed from 10s to 30s.

Example 12

The ethanol solution of 10 mg/ml cadmium nitrate was changed to the ethanol solution of lead methane sulfonate with a concentration of 50 mg/mL. When forming a liquid film, the spin coating speed was changed from 2000rpm to 5000rpm. After the liquid film was formed, the standing time was changed from 10s to 5000rpm. 5s.

Example 13

The ethanol solution of 10 mg/ml cadmium nitrate was changed to the ethanol solution of zinc perchlorate with a concentration of 5 mg/mL. When forming a liquid film, the number of spin coatings was changed from 1 to 2 times.

Example 14

Step (2) is changed to: place the quantum dot film in a 10 mg/ml cadmium nitrate ethanol solution, so that the lower side of the quantum dot film is in contact with the solution surface for 10 seconds, take out the quantum dot film, and rinse the surface of the quantum dot film with ethanol. Obtain functional membrane.

In the preparation of the device, "Use 10mg/ml cadmium nitrate ethanol solution to spin-coat (2000rpm) on the quantum dot film to form a film. After 10 seconds, spin-coat the quantum dot film with ethanol to obtain the luminescent layer" is changed to "Set with The substrates of multiple film layers are turned over, and the quantum dot film is immersed in a 10 mg/ml cadmium nitrate ethanol solution. After the lower side of the quantum dot film is in contact with the solution surface for 10 seconds, the surface of the quantum dot film is rinsed with ethanol to obtain the luminescent layer. , flip the substrate again so that the light-emitting layer is on top."

Example 15

This embodiment is basically the same as Embodiment 14. The only difference from Embodiment 14 is that in this embodiment:

The concentration of the cadmium nitrate ethanol solution used was changed from 10mg/ml to 5mg/mL, and the contact time was 30s.

Example 16

The concentration of the cadmium nitrate ethanol solution used was changed from 10mg/ml to 50mg/mL, and the contact time was 5s.

Example 17

The treatment solution used was changed from a 10 mg/ml cadmium nitrate ethanol solution to a mixed solution of manganese nitrate and copper nitrate dissolved in ethanol. In the mixed solution, the molar ratio of manganese nitrate and copper nitrate was 1:1, and the molar ratio of manganese nitrate and copper nitrate was 1:1. The total concentration is 10mg/ml.

Comparative example 1

This comparative example is basically the same as Example 1. The only difference from Example 1 is that in this comparative example:

Step (2) is reduced.

Comparative example 2

Preparation of quantum dot solution:

A quantum dot solution is provided, wherein the quantum dots are red quantum dots CdZnSe/ZnSeS/ZnS, the solvent is n-octane, and the concentration of the solution is 20 mg/mL.

Take 5 mL of the quantum dot solution, add 0.3 mL of 50 mmol/ml cadmium nitrate ethanol solution, stir thoroughly, and after 10 min, add 10 ml of ethyl acetate to wash, centrifuge to obtain a precipitate, redisperse the precipitate in n-octane solution, and quantify 15 mg/ ml to obtain the treated quantum dot solution.

Device preparation:

The only difference between the preparation steps of the device in this comparative example and Example 1 is that when preparing the luminescent layer, the treated quantum dot solution prepared in Comparative Example 2 is directly spin-coated on the hole transport layer to form a film to obtain the luminescent layer.

Comparative example 3

This comparative example is basically the same as comparative example 2. The only difference from comparative example 2 is that in this comparative example:

The added amount of cadmium nitrate ethanol solution is 0.5 mL. The obtained treated quantum dot solution exhibits aggregation phenomenon.

Comparative example 4

The treatment solution used is zinc nitrate ethanol solution.

Comparative example 5

The treatment liquid used is indium nitrate ethanol solution.

Experimental example 1

Take metal salt solutions (cadmium nitrate ethanol solution, calcium nitrate ethanol solution, aluminum nitrate ethanol solution, indium nitrate ethanol solution, manganese nitrate ethanol solution, platinum nitrate ethanol solution, zinc nitrate ethanol solution, copper nitrate ethanol solution, iron nitrate ethanol solution, Nickel nitrate ethanol solution) perform the following experiments:

A quantum dot solution is provided, wherein the quantum dots are red quantum dots CdZnSe/ZnSeS/ZnS, the solvent is n-octane, and the concentration of the solution is 20 mg/mL. Take 5 mL of quantum dot solution, add 0.3 mL of 50 mmol/ml metal salt solution, stir thoroughly, and after 10 min, add 10 ml of ethyl acetate to wash, centrifuge to obtain a precipitate, redisperse the precipitate in n-octane solution, and quantify 15 mg/ml. , to obtain the processed quantum dot solution.

A dynamic light scattering instrument was used to detect the hydrated particle size of the quantum dots in the quantum dot solution and the treated quantum dot solution, and the results were recorded in Table 1.

Table 1

It can be seen from Table 1:

The data of the hydrated particle size test reflects the comprehensive particle size of the quantum dots and ligands in the solution state. There are only one particle size distribution of quantum dots in the quantum dot solution. After adding a metal salt solution to the quantum dot solution, quantum dots of two particle sizes appear in the solution. The hydrated particle size distribution of the first quantum dot is within 30 ~50nm, the hydrated particle size of the second quantum dot is distributed between 10~20nm, and the hydrated particle size of the first quantum dot is larger than that of the second quantum dot. This is because the metal cations simultaneously interact with the anions on the surface of multiple quantum dots. Connection, such that adjacent quantum dots are bridged by metal cations, resulting in an increase in hydrated particle size;

Referring to Comparative Example 2, Comparative Example 3 and the above-mentioned experimental steps for hydrated particle size detection, it can be seen that when the amount of metal salt solution added is up to 0.5 ml, the treated quantum dot solution shows coagulation phenomenon. Obviously, the method of directly adding metal salt solution to the quantum dot solution can only allow the addition of a small amount of metal salt solution for treatment, which will inevitably lead to a lower content of the first quantum dots in the treated solution.

Experimental example 2

Detect the first metal cation content and the second metal cation content in the functional film prepared in Examples 1 to 17 and Comparative Example 1, where the first metal cation refers to the metal cation connecting the anions on the surface of adjacent quantum dots, that is, through treatment Metal cations introduced into the liquid, and the second metal cations refer to all metal cations contained in the quantum dot body. The results are recorded in Table 2. The detection method is as follows:

By characterizing the quantum dot film and quantum dot solution before treatment with a transmission electron microscope (TEM-EDS), the atomic percentage content of each atom of the quantum dot can be obtained, and the sum of the atomic percentage content of all metal atoms is calculated, which is Atomic percentage (At%) of the second metal cation;

By characterizing the treated quantum dot film and quantum dot solution using a transmission electron microscope (TEM-EDS), the atomic percentage of each atom in the treated sample can be obtained. If the treatment solution is used If the type of metal cation contained is the type already present in the quantum dot film or quantum dot solution before treatment, then the difference in content of the metal element before and after treatment is taken as the atomic percentage (At%) of the first metal cation. If the The type of metal cations contained in the treatment liquid is a new type that the quantum dot film or quantum dot solution before treatment does not have, then the atomic percentage content of the detected metal element is the atomic percentage content of the first metal cation (At %).

Table 2

After adjacent quantum dots are bridged by metal cations, the hydrated particle size of the quantum dot solution will increase, and because the metal cations are connected to the quantum dots, the quantum dot film will also contain the metal cations. Referring to Table 2, the data shows that after processing using the method of this application, the quantum dot film contains all The first metal cation. Combining the test results of Experimental Example 1, it can be concluded that after processing using the method of the present application, adjacent quantum dots in the quantum dot film are bridged through metal cations.

Experimental example 3

Test the fluorescent quantum dot yields of the functional films prepared in Examples 1 to 17 and Comparative Example 1 and the treated quantum dot solutions prepared in Comparative Examples 2, 4 and 5; Test Examples 1 to 17, Comparative Examples 1, Optoelectronic performance and lifespan of the devices prepared in 2, 4 and 5. The detection method is as follows:

The emission peak (EL), half-maximum width (FWHM) and current efficiency (CE) of the quantum dot light-emitting diode were tested and calculated by Keithley 2400 high-precision digital source meter, Ocean Optic USB2000+ spectrometer and LS-160 luminance meter respectively;

The test method of lifetime T95@1knit is the time it takes for the initial brightness L ₀ (nit) of the device to decay to 95% under constant current, and is converted into the aging time at 1000 nit.

The test results are shown in Table 3.

table 3

It can be seen from Table 3:

Compared with the light-emitting diode of Comparative Example 1, the light-emitting diodes of Examples 1 to 17 all have higher photoelectric performance and longer life T95@1000nit. Obviously, after using a treatment solution containing metal cations to treat the quantum dot film, , the metal cations form chemical bonds with the anions on the surface of the quantum dots, thereby passivating the anion dangling bonds on the surface of the quantum dots, reducing the defect states on the surface of the quantum dots, eliminating the non-radiative channels introduced by the defect states, and conducive to improving the quantum Fluorescence quantum yield (PLQY) of dots; at the same time, because adjacent quantum dots are connected through metal cations, the functional film is also made denser, the coupling effect is enhanced, the carrier transmission speed is increased, and higher excitation is obtained. The electron density improves the luminous efficiency and life of the light-emitting device; moreover, comparing Examples 1 to 10, it can be seen that when the metal cations contained in the treatment liquid used are Al ³⁺ , Mn ²⁺ , Pt ²⁺ , and Zn ^{2 +} , Fe ³⁺ , the effect on improving the luminous efficiency and life of the light-emitting device is better.

Compare Example 1 and Comparative Example 2, Example 7 and Comparative Example 4, and Example 4 and Comparative Example 5 respectively, and then compare them with Comparative Example 1 respectively. It can be seen that compared with the scheme of the present application, it is less effective in preparing quantum During the solution dispensing process, a treatment solution is added to modify the surface. If the final concentration of the added treatment solution is low (for example, less than 5 mmol/mL), although the photoelectric performance and lifespan of the device can be improved, the improvement effect will be limited. It is significantly lower than the photoelectric performance and lifespan of the device produced by the scheme of this application; moreover, combined with the results of Comparative Example 3 (the treated quantum dot solution obtained has agglomeration phenomenon), if the final concentration of the added treatment solution is too high , the quantum dot solution will be unstable and agglomeration will occur due to quantum dot bridging.

The functional film, its preparation method and the light-emitting device provided by the embodiments of the present application have been introduced in detail. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The above The description of the embodiments is only used to help understand the method and the core idea of the present application; at the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the present application. In summary, As mentioned above, the content of this specification should not be construed as a limitation on this application.

Claims

A functional film, wherein the functional film includes quantum dots and metal cations connecting at least two adjacent quantum dots, and the metal cations form chemical bonds with first anions on the surface of the quantum dots.
The functional film according to claim 1, wherein the functional film is composed of the quantum dots and the metal cations connecting at least two adjacent quantum dots.
The functional film according to claim 1 or 2, wherein the metal cations include one or more of divalent metal cations and trivalent metal cations.
The functional film according to claim 1 or 2, wherein the atomic percentage of the metal cations in the functional film is 0.1 to 5%.
The functional film according to claim 1 or 2, wherein in the functional film, the quantum dots with the metal cations connected to their surfaces are first quantum dots, and the hydrated particle size of the first quantum dots is 20 ~50nm.
The functional film according to claim 3, wherein the divalent metal cations include Cd 2+ , Zn 2+ , Ca 2+ , Mn 2+ , Pt 2+ , Cu 2+ , Co 2+ and Fe 2+ One or more of the trivalent metal cations include one or more of Al 3+ , Fe 3+ , Ni 3+ , Cr 3+ and In 3+ .
A method for preparing a functional membrane, which includes the following steps:

Providing a treatment solution and a quantum dot film, wherein the treatment solution contains metal cations;

The treatment liquid is brought into contact with the surface of the quantum dot film so that adjacent quantum dots in the quantum dot film are connected to each other through the metal cations to obtain a functional film.
The preparation method according to claim 7, wherein the metal cations include one or more of divalent metal cations and trivalent metal cations.
The preparation method according to claim 7, wherein the treatment solution further contains a second anion, and the second anion includes one or more of a nitrate ion, a sulfate ion, a sulfonate ion and a perchlorate ion.
The preparation method according to claim 7, wherein the time for the treatment liquid to contact the surface of the quantum dot film is 5-30s.
The preparation method according to claim 8, wherein the divalent metal cations include Cd 2+ , Zn 2+ , Ca 2+ , Mn 2+ , Pt 2+ , Cu 2+ , Co 2+ and Fe 2+ One or more of the trivalent metal cations include one or more of Al 3+ , Fe 3+ , Ni 3+ , Cr 3+ and In 3+ .
The preparation method according to claim 7, wherein the treatment liquid is brought into contact with the surface of the quantum dot film, so that adjacent quantum dots in the quantum dot film are connected to each other through the metal cations, to obtain The steps of functional membrane include:

The treatment liquid is placed on the surface of the quantum dot film to form a liquid film, and after standing, the liquid film is removed to obtain a functional film; or,

The quantum dot film is placed in the treatment liquid, so that at least one surface of the quantum dot film is in contact with the treatment liquid, and after standing, the quantum dot film is taken out, and the surface of the quantum dot film is removed. Treat the liquid to obtain a functional membrane.
The preparation method according to claim 12, wherein the treatment liquid is disposed on the surface of the quantum dot film, and the method of forming a liquid film includes: using a treatment liquid with a concentration of 2-5 mg/mL in the The surface of the quantum dot film is repeatedly coated multiple times to form a liquid film; or,

The method of disposing the treatment liquid on the surface of the quantum dot film to form a liquid film includes: coating the surface of the quantum dot film once with a treatment liquid with a concentration of 5-50 mg/mL to form a liquid film. membrane.
The preparation method according to claim 12, wherein the quantum dot film is placed in the treatment liquid, at least one surface of the quantum dot film is contacted with the treatment liquid, and the quantum dot film is taken out after standing. dot film and remove the treatment liquid on the surface of the quantum dot film to obtain a functional film, the concentration of the treatment liquid is 5-50 mg/mL.
A light-emitting device, which includes a stacked anode, a light-emitting layer and a cathode, the light-emitting layer includes a functional film, the functional film includes the functional film according to any one of claims 1 to 6, or, The functional film is prepared by the preparation method described in any one of claims 7 to 14.
The light-emitting device according to claim 15, wherein the quantum dots of the functional film are selected from one or more of single structure quantum dots and core-shell structure quantum dots, and the material of the single structure quantum dot is selected from II -One or more of Group VI compounds, Group IV-VI compounds, Group III-V compounds and Group I-III-VI compounds, wherein the Group II-VI compound is selected from CdS, CdSe, CdTe, ZnS , ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe ,CdZnSeS , one or more of CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, the IV-VI compound is selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, One or more of SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe and SnPbSTe, the III-V compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, One or more of GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs or InAlPSb, and the Group I-III-VI compound is selected from one of CuInS 2 , CuInSe 2 and AgInS 2 or more, the core of the quantum dots of the core-shell structure includes any one of the above single structure quantum dots, and the shell material of the quantum dots of the core-shell structure includes CdS, CdTe, CdSeTe, CdZnSe, CdZnS, CdSeS , ZnSe, ZnSeS, ZnS and one or more of the above single structure quantum dots.
The light-emitting device according to claim 15, wherein the anode and the cathode are independently selected from a metal electrode, a carbon material electrode, a metal oxide electrode or a composite electrode, the material of the metal electrode is selected from one or more of Ag, Al, Mg, Au, Cu, Mo, Yb, Ca and Ba, the material of the carbon material electrode is selected from one or more of graphite, carbon nanotubes, graphene and carbon fiber, the material of the metal oxide electrode is selected from one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO and AMO, and the composite electrode is selected from one or more of AZO/Ag/AZO, AZO/Al/AZO, ITO/Ag/ITO, ITO/Al/ITO, ZnO/Ag/ZnO, ZnO/Al/ZnO, TiO2 /Ag/TiO2, TiO2 /Al/ TiO2 , ZnS/Ag/ZnS and ZnS/Al/ZnS.
The light-emitting device according to claim 15, wherein the light-emitting device further includes a hole function layer provided between the anode and the light-emitting layer, the hole function layer includes a hole transport layer and/or Hole injection layer, the materials of the hole transport layer and the hole injection layer are independently selected from TFB, CuPc, PVK, Poly-TPD, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD, PEDOT :PSS, TAPC, MCC, F4-TCNQ, HATCN, 4,4',4'-tris(N-3-methylphenyl-Nphenylamino)triphenylamine, polyaniline, transition metal oxides, transition metals One or more of sulfide, transition metal tinide, doped graphene, non-doped graphene and C60.
The light-emitting device according to claim 15, wherein the light-emitting device further includes an electronic functional layer provided between the cathode and the light-emitting layer, the electronic functional layer including an electron transport layer and/or an electron injection layer. .
The light emitting device according to claim 19, wherein the electron transport layer and/or the The material of the electron injection layer includes inorganic materials and/or organic materials. The inorganic materials are selected from doped or non-doped metal oxides. The metal oxides include zinc oxide, barium oxide, aluminum oxide, nickel oxide, oxide Titanium, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanium oxide, zinc aluminum oxide, zinc manganese oxide, zinc tin oxide, lithium zinc oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, One or more of copper sulfide, zinc tin, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, and barium titanate. The doped elements include aluminum, magnesium, lithium, manganese, yttrium, and lanthanum. , one or more of copper, nickel, zirconium, cerium, and gadolinium, and the organic material is selected from quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, and hydroxyquinoline compounds. Kind or variety.