CN116156928A - Nano material, preparation method of nano material and electroluminescent device - Google Patents

Nano material, preparation method of nano material and electroluminescent device Download PDF

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CN116156928A
CN116156928A CN202111389320.7A CN202111389320A CN116156928A CN 116156928 A CN116156928 A CN 116156928A CN 202111389320 A CN202111389320 A CN 202111389320A CN 116156928 A CN116156928 A CN 116156928A
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metal oxide
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周礼宽
杨一行
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TCL Technology Group Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G9/00—Compounds of zinc
    • C01G9/02—Oxides; Hydroxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/50—Solid solutions
    • C01P2002/52—Solid solutions containing elements as dopants
    • C01P2002/54—Solid solutions containing elements as dopants one element only
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/60—Optical properties, e.g. expressed in CIELAB-values

Abstract

The nano material is used for coating a metal hydroxide layer on the surface of the nano metal oxide, so that defects on the surface of the nano metal oxide are passivated, the capture of electrons by the surface defects is reduced, and when the nano material is used as an electron transport layer of an electroluminescent device, the quenching effect of the luminescent layer can be improved, so that the stability of the device is improved. In addition, the metal hydroxide layer can inhibit the growth of nano metal oxide, prevent the agglomeration of nano materials and enhance the stability of the nano materials.

Description

Nano material, preparation method of nano material and electroluminescent device
Technical Field
The application relates to the field of materials, in particular to a nano material, a preparation method of the nano material and an electroluminescent device.
Background
Electroluminescent, also known as electroluminescence, is a physical phenomenon in which electrons excited by an electric field collide with a luminescence center to cause transition, change and recombination of electrons between energy levels to cause luminescence.
QLED (Quantum Dots Light-emission Diode) is an emerging electroluminescent device, which is composed of an Anode (Anode), a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), a light Emitting layer (EmL), an Electron Transport Layer (ETL) and a Cathode (Cathode), from which electrons and holes can be injected respectively, and finally recombine in the light Emitting layer to form exciton luminescence.
However, in the development process of the electroluminescent device represented by QLED, there are still many problems, such as quenching of excitons in the light emitting layer, which affect the stability of the device.
Disclosure of Invention
The embodiment of the application provides a nanomaterial, a preparation method of the nanomaterial and an electroluminescent device, and aims to reduce the capture of electrons by defects on the surface of the nanomaterial.
In a first aspect, the present application provides a nanomaterial comprising a nano metal oxide having a surface coated with a metal hydroxide layer.
Optionally, in the metal hydroxide layer, the metal hydroxide is selected from Al (OH) 3 LiOH or Mg (OH) 2 At least one of them.
Optionally, the nano metal oxide is selected from ZnO nanoparticles, and/or Al-doped ZnO nanoparticles.
Optionally, the thickness of the metal hydroxide layer is 0.5nm-1.5nm.
Optionally, the nanomaterial is composed of a nano metal oxide coated with a metal hydroxide layer on the surface, and/or the nano metal oxide is selected from ZnO nanoparticles doped with Al, and the metal hydroxide is selected from Al (OH) 3 。
In a second aspect, the present application also provides a method for preparing a nanomaterial, the method comprising:
mixing the nano metal oxide, the metal salt and the alkali solution to obtain the nano metal oxide coated with the metal hydroxide layer on the surface.
Optionally, in the alkaline solution, the alkali is selected from at least one of sodium hydroxide, potassium hydroxide or lithium hydroxide; and/or the number of the groups of groups,
the metal salt is selected from Al salt, li salt or Mg salt; and/or the number of the groups of groups,
the nano metal oxide is at least one selected from ZnO nano particles or Al-doped ZnO nano particles; and/or the concentration of the nano metal oxide is 0.5mg/mL to 2mg/mL.
Alternatively, the metal salt is selected from aluminum chloride, aluminum sulfate or aluminum acetate, and the nano metal oxide is selected from Al-doped ZnO nano particles.
Third aspect the present application also provides an electroluminescent device comprising a cathode, an anode, and an electron transporting layer and a light emitting layer arranged between the cathode and the anode, the light emitting layer being arranged close to the anode, the electron transporting layer being arranged close to the cathode, the material of the electron transporting layer comprising the nanomaterial of the first aspect or comprising the nanomaterial made by the method of the second aspect.
Optionally, the anode is selected from one or more of indium tin oxide, fluorine doped tin oxide, indium zinc oxide, graphene and carbon nanotubes; and/or the number of the groups of groups,
the material of the luminous layer is selected from chromium-free quantum dots, and the core of the chromium-free quantum dots is selected from at least one of InP, inGaP, inZnP; the shell material of the chromium-free quantum dot comprises one or more of GaP, znSe, znSeS, znS and the like; and/or the number of the groups of groups,
the cathode is selected from one or more of Al, ca, ba, ag.
The beneficial effects are that:
the application provides a nano material, a preparation method of the nano material and an electroluminescent device, wherein a metal hydroxide layer is covered on the surface of a nano metal oxide so as to passivate defects on the surface of the nano metal oxide, the capture of electrons by the surface defects is reduced, and when the nano material is used as an electron transport layer of the electroluminescent device, the quenching effect of the luminescent layer can be improved, so that the stability of the device is improved. In addition, the metal hydroxide layer can inhibit the growth of nano metal oxide, prevent the agglomeration of nano materials and enhance the stability of the nano materials.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that are required to be used in the description of the embodiments will be briefly described below.
Fig. 1 is a schematic flow chart of a method for preparing a nanomaterial according to an embodiment of the present application;
FIG. 2 is an electroluminescent device with a front structure according to an embodiment of the present application;
fig. 3 is an electroluminescent device of an inverted structure according to an embodiment of the present application;
fig. 4 is a schematic representation of an ultraviolet-visible (UV-Vis) absorption spectrum provided in an example of the present application.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.
The embodiment of the application provides a nano material, a preparation method of the nano material and an electroluminescent device. The following will describe in detail. The following description of the embodiments is not intended to limit the preferred embodiments. In addition, in the description of the present application, the term "comprising" means "including but not limited to". Various embodiments of the present application may exist in a range of forms; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the application; it is therefore to be understood that the range description has specifically disclosed all possible sub-ranges and individual values within that range. Whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the range referred to.
First, the embodiment of the application provides a nanomaterial, which comprises a nano metal oxide, wherein a metal hydroxide layer is coated on the surface of the nano metal oxide.
According to the method, the metal hydroxide layer is covered on the surface of the nano metal oxide, so that the defects on the surface of the nano metal oxide are passivated, the capture of electrons by the surface defects is reduced, and when the nano material is used as an electron transport layer of an electroluminescent device, the quenching effect of the luminescent layer can be improved, so that the stability of the device is improved. In addition, in the preparation process, the metal hydroxide layer can also inhibit the growth of nano metal oxide in the solution, prevent the agglomeration of nano materials and enhance the stability of the nano materials.
In some embodiments, in the metal hydroxide layer, the metal hydroxide is selected from Al (OH) 3 LiOH or Mg (OH) 2 At least one of (a) and (b).
In some embodiments, the nano-metal oxide is selected from ZnO nanoparticles, or Al-doped ZnO (ZnAlO) nanoparticles. These materials have high electron mobility and good band alignment, which can greatly improve the performance of the device.
In some embodiments, the nanomaterial is comprised of a nano metal oxide coated on a surface with a metal hydroxide layer.
Furthermore, the inventors found in the study that when the nano metal oxide is selected from Al-doped ZnO and the metal hydroxide is selected from Al (OH) 3 When the ZnO doped with Al has higher electron mobility and conductivity, the Al (OH) is used for preparing the ZnO 3 The surface of the Al-doped ZnO nano particle is covered, so that the quenching effect of the defect state on the surface on the quantum dot of the luminescent layer can be eliminated on the premise of high electron mobility. Furthermore, al (OH) 3 The crystal lattice dislocation defect at the interface can be reduced by having better lattice matching degree with the Al-doped ZnO nano-particles, so that the quenching effect of the defect state on the surface on the quantum dots of the luminescent layer can be eliminated on the premise of high electron mobility.
In some embodiments, the thickness of the metal hydroxide layer is less than or equal to 1.5nm, and in this thickness range, not only can the electron mobility and the conductivity of the electron transport layer be ensured, but also the function of passivating the defects on the surface of the nano metal oxide can be achieved. It will be appreciated that the thickness of the metal hydroxide layer may be taken from any value below 1.5nm, for example from 0.5nm to 1.5nm, and may specifically be 0.1nm, 0.2nm, 0.3nm, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm, 1.0nm, 1.1nm, 1.2nm, 1.3nm, 1.4nm, 1.5nm, etc., or other unlisted values below 1.5nm.
The application also provides a preparation method of the nanomaterial, as shown in fig. 1, the method comprises the following steps:
s10, providing nano metal oxide, metal salt and alkali solution.
S20, mixing the nano metal oxide, the metal salt and the alkali solution to obtain the nano metal oxide with the surface covered with the metal hydroxide layer.
In some embodiments, the step S20 includes: mixing the nano metal oxide with a first organic solvent of metal salt, and then slowly dropwise adding a second organic solvent of alkali to obtain the nano metal oxide with the surface covered with the metal hydroxide layer. For example, in one specific embodiment, the step S20 includes: adding 4mL of 0.25M aluminum acetate ethanol solution into ZnAlO nanoparticle reaction solution with the concentration of 0.5mg/mL to 2mg/mL, slowly dropwise adding 4mL of 0.25M sodium hydroxide methanol solution into the solution at the concentration of 5mL/h under stirring, and reacting to finally generate Al (OH) coated with the outer layer 3 ZnAlO of (a).
In some embodiments, the base in the alkaline solution is selected from at least one of sodium hydroxide, potassium hydroxide, or lithium hydroxide; the metal salt is selected from Al salt, li salt or Mg salt; the nano metal oxide is selected from ZnO nano particles, or ZnO (ZnAlO) nano particles doped with Al.
In some embodiments, the metal salt is selected from aluminum chloride, aluminum sulfate, or aluminum acetate, and the nano-metal oxide is selected from Al-doped ZnO nanoparticles.
In some embodiments, the concentration of the nano metal oxide is 0.5mg/mL to 2mg/mL (milligrams per milliliter), if the concentration is too high, the polycondensation reaction occurs, if the concentration is too low, the yield is affected, and it is understood that the concentration of the nano metal oxide can be arbitrarily selected from the range of 0.5mg/mL to 2mg/mL, for example: 0.5mg/mL, 0.6mg/mL, 0.7mg/mL, 0.8mg/mL, 0.9mg/mL, 1.0mg/mL, 1.1mg/mL, 1.2mg/mL, 1.3mg/mL, 1.4mg/mL, 1.5mg/mL, 1.6mg/mL, 1.7mg/mL, 1.8mg/mL, 1.9mg/mL, 2.0mg/mL, etc., or other non-listed values in the range of 0.5mg/mL to 2mg/mL.
In some embodiments, in the step S20, the nano metal oxide is prepared by a sol-gel method using the following reagents: zinc salt, solvent, alkali and precipitant, the specific steps include:
(1) Zinc salt is dissolved in a solvent under the condition of room temperature to obtain zinc salt solution, and alkali is also dissolved or diluted in another part of the same or different solvent under the condition of room temperature to obtain alkali liquor;
(2) The temperature of the zinc salt solution is regulated to 0-70 ℃, alkali liquor is dripped into the salt solution according to the molar ratio of hydroxyl ions to zinc ions of (1.5-2.5): 1, and then the mixed solution is continuously stirred/reacted for 30 min-4 h under the condition that the reaction temperature is kept to 0-70 ℃;
(3) Adding the following volume ratio (2-6) into the mixed solution after the reaction: 1, a white precipitate was produced in the mixed solution. The mixed solution was centrifuged, and the resulting white precipitate was dissolved again in the reaction solvent, and this washing process was repeated a plurality of times to remove the reactants not participating in the reaction. Finally, the obtained white precipitate is dissolved in a solvent to obtain zinc oxide colloid solution.
Wherein the zinc salt is at least one selected from zinc acetate, zinc nitrate, zinc sulfate, zinc chloride and the like; the solvent is selected from at least one of water, alcohols and other solvents with relatively high polarity, for example: water, methanol, ethanol, propanol, butanol, ethylene glycol monomethyl ether, DMSO, or the like; the alkali is at least one selected from potassium hydroxide, sodium hydroxide, lithium hydroxide, TMAH, ammonia water, ethanolamine, ethylenediamine and the like; the precipitant is at least one selected from but not limited to solvents with weaker polarity, and concretely comprises but not limited to isoparaffins such as ethyl acetate, acetone, n-hexane and n-heptane.
The present application also provides an electroluminescent device comprising: the cathode and anode are arranged, the electron transport layer and the luminescent layer are arranged between the cathode and the anode, the luminescent layer is arranged close to the anode, the electron transport layer is arranged close to the cathode, and the material of the electron transport layer comprises the nanomaterial. In some embodiments, the electronic light emitting device is a quantum dot light emitting diode (QLED).
The electroluminescent device in the embodiment of the application may be a positive structure or an inverted structure. In an electroluminescent device, the cathode or anode further comprises a substrate on the side remote from the light-emitting layer, the anode being arranged on the substrate in an upright configuration and the cathode being arranged on the substrate in an inverted configuration. A hole-transporting layer, a hole-injecting layer, and other hole-functional layers may be further disposed between the anode and the light-emitting layer. For example:
fig. 2 shows a schematic diagram of a positive structure of the electroluminescent device according to the embodiment of the application, as shown in fig. 2, the positive structure quantum dot device includes a substrate 1, an anode 2 disposed on a surface of the substrate 1, a hole injection layer 3 disposed on a surface of the anode 2, a hole transport layer 4 disposed on a surface of the hole injection layer 3, a light emitting layer 5 disposed on a surface of the hole transport layer 4, an electron transport layer 6 disposed on a surface of the light emitting layer 5, and a cathode 7 disposed on a surface of the electron transport layer 6, where the electron transport layer material 6 is selected from nano metal oxides covered with a metal hydroxide layer, and the light emitting layer 5 is selected from quantum dot materials.
Fig. 3 shows a schematic diagram of an inverted structure of a quantum dot device according to an embodiment of the present application, as shown in fig. 3, where the quantum dot device with an inverted structure includes a substrate 1, a cathode 7 disposed on a surface of the substrate 1, an electron transport layer 6 disposed on a surface of the cathode 7, a light emitting layer 5 disposed on a surface of the electron transport layer 6, a hole transport layer 4 disposed on a surface of the light emitting layer 5, a hole injection layer 3 disposed on a surface of the hole transport layer 4, and an anode 2, and the electron transport layer 6 is made of a nano metal oxide covered with a metal hydroxide layer, and the light emitting layer 5 is made of a quantum dot material.
The electroluminescent device is of a positive structure or an inverted structure, the light-emitting layer is adjacent to the electron transport layer, an interface between the light-emitting layer and the electron transport layer is formed, the defect on the surface of the nano metal oxide can seriously quench excitons at the interface, and the defect can be expressed as quenching of fluorescence quantum efficiency of the quantum dot material, so that the photoelectric performance of the device is degraded. According to the embodiment of the application, the surface of the nano metal oxide is covered with the metal hydroxide layer, so that the defects on the surface of the nano metal oxide are passivated, the capture of electrons by the surface defects is reduced, the quenching effect of the light-emitting layer is improved, and the stability of the device is improved.
In embodiments of the present application, the materials of the respective functional layers may be the following materials, for example:
the anode is selected from one or more of indium tin oxide, fluorine doped tin oxide, indium zinc oxide, graphene and carbon nano-tube.
The material of the hole injection layer is selected from, but not limited to, one or more of (3, 4-ethylenedioxythiophene) -poly (styrenesulfonic acid) (PEDOT: PSS), nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, copper oxide.
The hole transport layer material is selected from but not limited to TFB (poly (9, 9-dioctylfluorene-CO-N- (4-butylphenyl) diphenylamine)), P 3 HT (3-hexyl-substituted polythiophene), PVK (poly (9-vinylcarbazole)), poly-TPD (poly [ bis (4-phenyl) (4-butylphenyl) amine)]) One or more of TCTA (4, 4 '-tris (carbazol-9-yl) triphenylamine), CBP (4, 4' -bis (9-carbazol) biphenyl), and the like.
The cathode is selected from, but not limited to, one or more of Al, ca, ba, ag.
In some embodiments, the luminescent layer is a red, green, blue quantum dot, especially a red, green, blue quantum dot of a cadmium-free system. Because the electron of the electroluminescent device of the quantum dot of the cadmium-free system has higher carrier mobility than the hole, and the problem of unbalanced carrier injection level exists, the nanomaterial provided in the embodiment of the application has the effects of better improving the electron injection efficiency of the electroluminescent device of the quantum dot of the cadmium-free system and avoiding exciton quenching of an initiation interface.
In some embodiments, the red, green and blue quantum dots of the cadmium-free system are composed of a core-shell structure, and the shell layer has the functions of passivating the surface defect state of the quantum dot core to improve the fluorescence yield of the quantum dot, and binding the electron and hole wave functions in the core to prevent excitons from delocalizing to the non-radiative recombination center of the shell layer surface state to be quenched. The core of the quantum dot comprises binary, multi-element and multi-element gradual-change alloy composed of II-VI group elements and III-V group elements and quantum dots with core-shell components, and the quantum dot comprises at least one of InP, inGaP, inZnP; the shell material of the quantum dot comprises one or more of GaP, znSe, znSeS, znS and the like.
The inventor finds that the electron of the quantum dot electroluminescent device of the cadmium-free system has higher carrier mobility than the hole, and the problem of unbalanced carrier injection level is caused mainly by larger energy level barrier between the luminescent layer and the electron transmission layer and less electron injection. Therefore, in order to improve the conductivity, the material of the electron transport layer is ZnO nano particles or ZnO nano particles doped with Al, and the material has high electron mobility and good energy band arrangement, so that the performance of the device can be greatly improved. Further, the method can be realized by adding oxygen vacancy defect states on the surfaces of ZnO nano-particles or Al-doped ZnO nano-particles, but as the defect states increase, quantum dot exciton quenching at the interface of the light-emitting layer and the electron transport layer is caused. Therefore, in the embodiment of the application, the surface of the nano metal oxide is covered with the metal hydroxide layer, so that the electron injection efficiency of the nano metal oxide is improved, the problem of exciton quenching of an initiation interface is avoided, and the photoelectric performance of the cadmium-free quantum dot device is integrally improved.
The present application is described in detail by examples below.
Example 1
The embodiment provides an electron transport film and a positive electroluminescent device. Wherein, the liquid crystal display device comprises a liquid crystal display device,
the method for electron transport film comprises: preparing a QD film on clean and dry quartz glass by a spin coating film forming process by using an n-octane solution of red quantum dots InP/ZnSe/ZnS with the mass concentration of 20mg/mL at a rotating speed of 3000 rpm; znAlO/Al (OH) 3 (Al-doped ZnO surface is covered with a layer of Al (OH) 3 Layer) on the QD film at 4000rpm with 30mg/mL ethanol solution, through glass cover plate encapsulation, QD film and QD/ZnAlO/Al (OH) were obtained 3 A film.
The preparation method of the positive electroluminescent device comprises the following steps: hole injection layer PEDOT spin-coated on anode layer ITO: PSS material, annealing at 100 ℃ for 15min; then forming a hole transport layer TFB on the hole injection layer, and annealing at 100 ℃ for 15min; forming an InP/ZnSe/ZnS red quantum dot luminescent layer on the hole transport layer as a bearing part, and annealing at 80 ℃ for 10min to remove residual solvent of the luminescent layer film; spin coating a light-emitting layer containing ZnAlO/Al (OH) 3 Obtaining an electron transport layer; finally, the electroluminescent device is formed by evaporating an Ag cathode layer and packaging.
Example 2
The embodiment provides an electron transport film and a positive electroluminescent device. Wherein, the liquid crystal display device comprises a liquid crystal display device,
the method for electron transport film comprises: preparing a QD film on clean and dry quartz glass by a spin coating film forming process by using an n-octane solution of green quantum dots InP/GaP/ZnS with the mass concentration of 15mg/mL at a rotating speed of 3000 rpm; then ZnO/Al (OH) 3 (ZnO surface is covered with a layer of Al (OH) 3 Layer) on the QD film at 4000rpm with 30mg/mL ethanol solution, and packaging with a glass cover plate to obtain a QD film and QD/ZnO/Al (OH) 3 A film.
The preparation method of the positive electroluminescent device comprises the following steps: hole injection layer PEDOT spin-coated on anode layer ITO: PSS material, annealing at 100 ℃ for 15min; a hole transport layer TFB is then formed over the hole injection layer,annealing at 100 ℃ for 15min; forming an InP/GaP/ZnS green quantum dot luminescent layer on the hole transport layer as a bearing part, and annealing at 80 ℃ for 10min to remove residual solvent of the luminescent layer film; spin coating of a light-emitting layer containing ZnO/Al (OH) 3 Obtaining an electron transport layer; finally, an Al cathode layer is evaporated, and the electroluminescent device is formed by encapsulation.
Example 3
The embodiment provides an electron transport film and a positive electroluminescent device. Wherein, the liquid crystal display device comprises a liquid crystal display device,
the method for electron transport film comprises: preparing a QD film on clean and dry quartz glass by a spin coating film forming process by using an n-octane solution of blue quantum dots ZnSeTe/ZnSeS/ZnS with the mass concentration of 10mg/mL at a rotating speed of 3000 rpm; then ZnAlO/Al (OH) is used 3 Spin-coating 30mg/mL ethanol solution on the QD film at 4000rpm, and packaging by a glass cover plate to obtain the QD film and QD/ZnAlO/Al (OH) respectively 3 A film.
The preparation method of the positive electroluminescent device comprises the following steps: hole injection layer PEDOT spin-coated on anode layer ITO: PSS material, annealing at 100 ℃ for 15min; then forming a hole transport layer TFB on the hole injection layer, and annealing at 100 ℃ for 15min; forming a luminescent layer of ZnSeTe/ZnSeS/ZnS blue quantum dots on the hole transport layer serving as a bearing part, and annealing at 80 ℃ for 10min to remove residual solvent of the luminescent layer film; spin coating a light-emitting layer containing ZnAlO/Al (OH) 3 Obtaining an electron transport layer; finally, the electroluminescent device is formed by evaporating an Ag cathode layer and packaging.
Comparative example 1
Comparative example 1 is substantially the same as example 1 except that: the material of the electron transport layer/film is ZnAlO.
Comparative example 2
Comparative example 2 is substantially the same as example 2 except that: the material of the electron transport layer/film is ZnO.
Comparative example 3
Comparative example 3 is substantially the same as example 2 except that: the material of the electron transport layer/film is ZnAlO.
Verification example 1
The present application provides verification example 1 for testing the fluorescence efficiency of the electron transport films provided in examples 1 to 3 and comparative examples 1 to 3, respectively. The test results are shown in Table 1.
TABLE 1
Figure BDA0003364726630000101
As can be seen from Table 1, for the red QD film provided in example 1, the fluorescence quantum efficiency of the QD film was about 62%, the electron transport layer using ZnAlO was disposed on the red QD film, the fluorescence quantum efficiency was reduced to about 20%, and ZnAlO/Al (OH) was used 3 The electron transport layer of (2) is arranged on the red QD film, the reduction amplitude of the fluorescence quantum efficiency is less than 10 percent, and almost no change can be considered; for the green QD film provided in example 2, the fluorescence quantum efficiency was about 45%, and the electron transport film using ZnO was overlaid on the green QD film, the fluorescence quantum efficiency was reduced to 13%, using ZnO/Al (OH) 3 As the electron transport film is covered on the green QD film, the fluorescence quantum efficiency reduction range is less than 20%, and the quenching effect is obviously reduced; for the blue quantum dot film provided in example 3, the fluorescence quantum efficiency was about 60%, the electron transport film using ZnAlO was overlaid on the blue QD film, the fluorescence quantum efficiency was reduced to 15%, and ZnAlO/Al (OH) was used 3 As the electron transport film is covered on the blue QD film, the fluorescence quantum efficiency reduction range is less than 10%, and the quenching effect is obviously reduced.
Therefore, the fluorescence efficiency of the red, blue or green QD film is reduced after an electron transport layer is arranged on the surface of the film, because the defect exists on the surface of ZnO or ZnAlO in the electron transport layer material, thus quenching effect is caused, but a layer of Al (OH) is arranged on the surface of ZnO or ZnAlO 3 Thereafter, defects on the surface of ZnO or ZnAlO may be passivated, and thus the quenching effect may be reduced.
Verification example 2
To verify that provided in the embodiments of the present applicationZnAlO/Al(OH) 3 Stability of nanomaterial, this application also provides verification example 2, taking 5mL of ZnAlO and 30mg/mL of ZnAlO/Al (OH), respectively 3 Ethanol solution, 5mL,30mg/mL ZnO and ZnO/Al (OH) 3 Ethanol solution, placed in room temperature for 24h, and particle size change measured by Dynamic Light Scattering (DLS) of particle size, and also for ZnO and ZnO/Al (OH) 3 And ZnO/Al (OH) after 24 hours of standing 3 Ultraviolet-visible (UV-Vis) absorption spectroscopy was performed. Particle size Dynamic Light Scattering (DLS) test results are shown in table 2 and ultraviolet-visible (UV-Vis) absorption spectrum test results are shown in fig. 4.
TABLE 2
Sequence number Material Initial particle size (nm) Final particle size (nm)
Comparative example 1 ZnAlO 6 22
Example 1 ZnAlO/Al(OH) 3 6.5 9
Comparative example 2 ZnO 5.5 18
Example 2 ZnO/Al(OH) 3 5.8 8
ZnAlO/Al (OH) in comparative example 1 and comparative example 1, respectively 3 And ZnAlO two electron transport layer materials, the environmental storage stability is found, when the materials are placed in an air environment at normal temperature for 24 hours, the ZnAlO becomes turbid, and ZnAlO/Al (OH) 3 Still clear and transparent in appearance, as seen from Table 2, the particle size of ZnAlO increased significantly from 6nm to 22nm, znAlO/Al (OH) 3 The particle size is increased from 6.5nm to 9nm, and the change is small; by ZnO/Al (OH) in comparative example 2 and comparative example 2 3 And ZnO, the environmental storage stability of the two electron transport layer materials was found, and the materials were left under an ambient air atmosphere for 24 hours, although ZnO and ZnO/Al (OH) 3 The appearance was still clear and transparent, but the ZnO particle size increased from 5.5nm to 18nm, znO/Al (OH) 3 The particle size increased from 5.8nm to 8nm. The above all indicate Al (OH) 3 The layer can obviously improve the stability of ZnO or ZnAlO nano particles.
As can also be seen from FIG. 4, the absorption peak of example 2 changed less than that of comparative example 2, indicating Al (OH) 3 The layer can obviously improve the stability of ZnO nano-particles.
Verification example 3
Verification example 3 was used to test the optoelectronic performance and lifetime of the electroluminescent devices provided in examples and comparative examples, and the lifetime test of the devices used a 128-way lifetime test system customized by new vision company, guangzhou. The system architecture is used for driving the QLED by a constant voltage and constant current source and testing the change of voltage or current; a photodiode detector and a test system for testing the brightness (photocurrent) variation of the QLED; the luminance meter tests the luminance (photocurrent) of the calibrated QLED. The test results are shown in Table 3.
TABLE 3 Table 3
Figure BDA0003364726630000121
Note that: T95@1Knit represents the time taken for the device to decay from 100% to 95% at a luminance of 1000nit, calculated from the values of L and T95; C.E shows the current efficiency of the device, and the higher C.E the better the device performance on the premise that the light emitting area and the driving current are consistent.
As can be seen from Table 3, the electroluminescent devices provided in examples 1 to 3 are significantly superior in current efficiency and lifetime to those of comparative examples 1 to 3, because of ZnO/Al (OH) 3 Or ZnAlO/Al (OH) 3 The electron mobility of the electron transport films produced was high, so that the carrier levels in the electroluminescent devices tended to be balanced, and thus example 1 to example 3 obtained higher current efficiency and lifetime data.
The above describes in detail a nanomaterial, a method for preparing the nanomaterial, and an electroluminescent device provided in the embodiments of the present application, and specific examples are applied to illustrate principles and embodiments of the present application, where the above description of the examples is only used to help understand the method and core idea of the present application; meanwhile, those skilled in the art will have variations in the specific embodiments and application scope in light of the ideas of the present application, and the present description should not be construed as limiting the present application in view of the above.

Claims (10)

1. A nanomaterial characterized in that the nanomaterial comprises a nano metal oxide, and a metal hydroxide layer is coated on the surface of the nano metal oxide.
2. Nanomaterial according to claim 1, characterized in that in the metal hydroxide layer the metal hydroxide is selected from Al (OH) 3 LiOH or Mg (OH) 2 At least one of them.
3. Nanomaterial according to claim 1, characterized in that the nano metal oxide is selected from ZnO nanoparticles, and/or Al doped ZnO nanoparticles.
4. The nanomaterial of claim 1, wherein the metal hydroxide layer has a thickness of 0.5nm to 1.5nm.
5. Nanomaterial according to claim 1, characterized in that it consists of a nano-metal oxide coated with a metal hydroxide layer on the surface and/or selected from Al-doped ZnO nanoparticles, the metal hydroxide being selected from Al (OH) 3 。
6. A method of preparing a nanomaterial, the method comprising:
mixing the nano metal oxide, the metal salt and the alkali solution to obtain the nano metal oxide coated with the metal hydroxide layer on the surface.
7. The method according to claim 6, wherein in the alkaline solution, the alkali is at least one selected from sodium hydroxide, potassium hydroxide, and lithium hydroxide; and/or the number of the groups of groups,
the metal salt is selected from Al salt, li salt or Mg salt; and/or the number of the groups of groups,
the nano metal oxide is at least one selected from ZnO nano particles or Al-doped ZnO nano particles; and/or the number of the groups of groups,
the concentration of the nano metal oxide is 0.5mg/mL to 2mg/mL.
8. The method of claim 7, wherein the metal salt is selected from aluminum chloride, aluminum sulfate, or aluminum acetate, and the nano-metal oxide is selected from Al-doped ZnO nanoparticles.
9. An electroluminescent device, comprising: a cathode, an anode, and an electron transport layer and a light emitting layer disposed between the cathode and the anode, the light emitting layer disposed proximate the anode, the electron transport layer disposed proximate the cathode, the electron transport layer comprising the nanomaterial of any of claims 1-5 or the nanomaterial made by the method of any of claims 6-8.
10. An electroluminescent device as claimed in claim 9, characterized in that,
the anode is selected from one or more of indium tin oxide, fluorine doped tin oxide, indium zinc oxide, graphene or carbon nano-tube; and/or the number of the groups of groups,
the material of the luminous layer is selected from chromium-free quantum dots, and the core of the chromium-free quantum dots is selected from at least one of InP, inGaP or InZnP; the shell material of the chromium-free quantum dot comprises one or more of GaP, znSe, znSeS or ZnS; and/or the number of the groups of groups,
the cathode is selected from one or more of Al, ca, ba, ag.
CN202111389320.7A 2021-11-19 2021-11-19 Nano material, preparation method of nano material and electroluminescent device Pending CN116156928A (en)

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