WO2022143568A1 - 复合电子传输材料及其制备方法和发光二极管 - Google Patents

复合电子传输材料及其制备方法和发光二极管 Download PDF

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WO2022143568A1
WO2022143568A1 PCT/CN2021/141799 CN2021141799W WO2022143568A1 WO 2022143568 A1 WO2022143568 A1 WO 2022143568A1 CN 2021141799 W CN2021141799 W CN 2021141799W WO 2022143568 A1 WO2022143568 A1 WO 2022143568A1
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electron transport
transport material
metal oxide
composite
shell layer
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French (fr)
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徐威
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Tcl科技集团股份有限公司
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Priority to US18/270,716 priority Critical patent/US20240076197A1/en
Publication of WO2022143568A1 publication Critical patent/WO2022143568A1/zh

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    • C—CHEMISTRY; METALLURGY
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    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G9/00—Compounds of zinc
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    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H10K50/115—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising active inorganic nanostructures, e.g. luminescent quantum dots
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    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
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    • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
    • H10K85/113—Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
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    • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
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    • H10K85/10—Organic polymers or oligomers
    • H10K85/151—Copolymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
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    • C01—INORGANIC CHEMISTRY
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    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
    • C01P2004/84—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases one phase coated with the other
    • C—CHEMISTRY; METALLURGY
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    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
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    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2102/00—Constructional details relating to the organic devices covered by this subclass
    • H10K2102/301—Details of OLEDs
    • H10K2102/331—Nanoparticles used in non-emissive layers, e.g. in packaging layer
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    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2102/00—Constructional details relating to the organic devices covered by this subclass
    • H10K2102/301—Details of OLEDs
    • H10K2102/361—Temperature
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    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/14—Carrier transporting layers
    • H10K50/16—Electron transporting layers
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    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
    • H10K71/10—Deposition of organic active material
    • H10K71/12—Deposition of organic active material using liquid deposition, e.g. spin coating
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    • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
    • H10K71/40—Thermal treatment, e.g. annealing in the presence of a solvent vapour

Definitions

  • the application belongs to the field of optoelectronic technology, and in particular relates to a composite electron transport material, a preparation method thereof, and a light-emitting diode.
  • Light-emitting diodes such as quantum dot electroluminescent diodes (QLED) have continuously adjustable light-emitting wavelengths in the visible light range, narrow light-emitting line widths in the range of 15-20 nm, high light-emitting color saturation, and light-emitting color gamut up to 90% of the BT2020 standard color gamut. Such advantages have attracted widespread attention.
  • quantum dots are inorganic nanocrystals as light-emitting materials. After being prepared into devices, they have a long theoretical life, good device stability, fast response time, low operating voltage, high contrast, and can be made into large-size and flexible display panels. The hottest next-generation display technology.
  • light-emitting diodes especially QLEDs
  • blue QLEDs have T50>10,000 hours at 100 cd m -2
  • the lifespan of blue quantum dot devices cannot yet meet commercialization requirements.
  • the short working lifetime of blue QLEDs is due to the type II structure between the quantum dots and the electron transport layer (ETL), excited electrons in the blue quantum dots (QDs) easily accumulate space charges in the ETL and lead to the working of the device voltage rises.
  • ETL electron transport layer
  • the lifetime of the red QD device is mainly affected by the slow degradation of the hole transport layer, while the reduction in the lifetime of the blue QLED is caused by the rapid degradation from the QD-ETL junction. Therefore, further improving the conductivity and band gap of the electron transport layer and obtaining high-efficiency electron transport materials are the prerequisites for improving the working life of blue quantum dot QLEDs.
  • the present application provides a composite electron transport material and a preparation method thereof, and a light emitting diode containing the composite electron transport material, so as to solve the problem of low electron transport and injection efficiency caused by the relatively narrow forbidden band width of the existing electron transport material, and the electron transport layer and the luminescence The technical problem of high injection barrier between layers.
  • the composite electron transport material of the present application comprises a core body and at least one shell layer coated on the core body, the core body material is an inorganic electron transport material, the shell layer material includes a metal oxide, and the metal oxide has a wide band gap Band gaps of inorganic electron transport materials.
  • the metal oxide includes at least one of Yb 2 O 3 , La 2 O 3 , LaTi 2 O 7 , Nd 2 O 3 , ZrO 2 , and NiO.
  • the inorganic electron transport material includes at least one of ZnO and TiO 2 .
  • the thickness of the shell layer is 1-6 nm.
  • the particle size of the nucleus is 2-5 nm.
  • the shell layer includes more than two layers, and the core body is sequentially coated in the order that the first shell layer is coated on the core body and the second shell layer is coated on the first shell layer, and the core body is covered from the core body to the outer surface of the shell layer. direction, the band gap gradient of each shell increases.
  • the material of the first shell layer includes at least one of LaTi 2 O 7 and NiO.
  • the thickness of the first shell layer is 1-3 nm.
  • the second shell material includes at least one of La 2 O 3 and ZrO 2 .
  • the thickness of the second shell layer is 1-3 nm.
  • the shell layer is two layers, and the composite electron transport materials are ZnO@LaTi 2 O 7 @La 2 O 3 , ZnO@NiO@ZrO 2 , TiO 2 @LaTi 2 O 7 @La 2 O 3 , TiO 2 @ At least one of NiO@ZrO 2 ; wherein, @ represents coating.
  • a doped thin layer is formed at the interface between the core body and the shell layer.
  • a method for preparing a composite electron transport material comprises the following steps:
  • the core body dispersion solution is mixed with the first precursor solution and the first heat treatment is performed, so that the first metal oxide precursor undergoes a redox reaction, and the first metal oxide shell layer is grown in-situ on the surface of the inorganic electron transport material particles, obtain composite particles;
  • the band gap of the first metal oxide in the first metal oxide shell layer is wider than the band gap of the inorganic electron transport material.
  • the temperature of the first heat treatment is 20-80°C.
  • the mass ratio of the inorganic electron transport material particles to the first metal oxide precursor is 1:(0.2-3).
  • the mixed solution formed by the core body dispersion solution and the first precursor solution is further added with a first ligand, and the concentration of the first ligand in the mixed solution is 0.01-0.5 mg/mL.
  • the first metal oxide precursor includes a corresponding metal salt that generates at least one of Yb 2 O 3 , La 2 O 3 , LaTi 2 O 7 , Nd 2 O 3 , ZrO 2 , and NiO.
  • the first ligand includes at least one of ethylene glycol, glycerol, ethanolamine, and tetramethylammonium hydroxide.
  • the composite particles are prepared into a composite particle dispersion solution
  • the composite particle dispersion solution is mixed with the second precursor solution and the second heat treatment is performed, so that the second metal oxide precursor undergoes a redox reaction, and the second metal oxide shell layer is grown in-situ on the surface of the composite particle;
  • the band gap of the second metal oxide in the second metal oxide shell layer is wider than the band gap of the first metal oxide.
  • the temperature of the second heat treatment is 20-80°C.
  • the mass ratio of the composite particles to the second metal oxide precursor is 1:(0.2-3).
  • the mixed solution formed by the composite particle dispersion solution and the second precursor solution is further added with a second ligand, and the concentration of the second ligand in the mixed solution is 0.01-0.5 mg/mL.
  • the second metal oxide precursor includes a corresponding metal salt that generates at least one of La 2 O 3 , ZrO 2 , Yb 2 O 3 , LaTi 2 O 7 , Nd 2 O 3 , and NiO.
  • the second ligand includes at least one of ethylene glycol, glycerol, ethanolamine, and tetramethylammonium hydroxide.
  • a light emitting diode in yet another aspect of the present application, includes an electron transport layer, and the material of the electron transport layer includes the composite electron transport material of the present application or the composite electron transport material prepared by the preparation method of the composite electron transport material of the present application.
  • the light emitting diodes are QLED and OLED.
  • the light emitting diodes are blue light emitting diodes.
  • the composite electron transport material of the present application adopts a metal oxide with a relatively wide band gap as a shell layer and a metal oxide with a relatively narrow band gap as a core inorganic electron transport material, so as to realize the synergistic effect between the metal oxide and the inorganic electron transport material. , so that the metal oxide can effectively passivate the surface defects of the inorganic electron transport material, and form a doped conductive film layer at the coating interface of the inorganic electron transport material particles, and at the same time increase the band gap of the inorganic electron transport material and improve the inorganic electron transport material.
  • the conduction band energy level of the material can effectively improve the electrical conductivity and the electron transport and injection ability of the composite electron transport material, effectively reduce the exciton quenching of the composite electron transport material to luminescent materials such as quantum dots, and reduce the composite electron transport material.
  • the electron injection potential barrier between the electron transport layer formed by the electron transport material and the light emitting layer such as the quantum dot light emitting layer can effectively improve the light emitting diode containing the electron transport layer formed by the composite electron transport material.
  • the light emitting diode can further be a blue light emitting diode. efficiency and longevity.
  • At least one shell layer of a metal oxide containing a wide band gap is grown in situ on the surface of the inorganic electron transport material particles, on the one hand, it can enable the gap between the wide band gap metal oxide and the inorganic electron transport material. It plays a synergistic role in the above composite electron transport material of the present application, so that the surface defects of the inorganic electron transport material contained in the prepared composite electron transport material can be effectively passivated, and the band gap and conduction band energy level of the inorganic electron transport material are increased. and electrical conductivity; on the other hand, the preparation conditions are easy to control, so that the prepared composite electron transport material has stable performance, high preparation efficiency and low cost.
  • the electron transport layer contains in the light-emitting diode of the present application is the composite electron transport material of the present application, the electron transport layer has high electron transport and injection efficiency, which can effectively reduce the quenching and quenching of excitons in the light-emitting layer.
  • the electron injection potential barrier between the electron transport layer and the light-emitting layer is reduced, and the light-emitting efficiency and lifespan of the light-emitting diode are improved.
  • FIG. 1 is a schematic structural diagram of a composite electron transport material containing a single-layer shell in an embodiment of the present application
  • FIG. 2 is a schematic structural diagram of a composite electron transport material containing a double-layer shell in an embodiment of the present application
  • FIG. 3 is a schematic diagram of the process flow of the preparation method of the composite electron transport material according to the embodiment of the present application.
  • FIG. 4 is a schematic structural diagram of a positive light-emitting diode according to an embodiment of the present application.
  • FIG. 5 is a schematic structural diagram of an inversion light-emitting diode according to an embodiment of the present application.
  • Fig. 6 is the structural representation of the doped zinc oxide provided by comparative example 11;
  • the embodiments of the present application provide a composite electron transport material.
  • the composite electron transport material has a core-shell structure, as shown in FIG. 1 and FIG. 2 , which includes a core body 1 and a shell layer 2 that coats the core body 1 .
  • the material of the core body 1 contained in the composite electron transport material is an inorganic electron transport material.
  • the inorganic electron transport material may be a conventional inorganic electron transport material.
  • the inorganic electron transport material includes at least one of ZnO and TiO 2 .
  • the core body 1 is a nanoparticle, such as a particle size of 2-5 nm. Inorganic electron transport materials with diameters in this range have better crystallinity, which is beneficial to the coating of the shell layer and the doping of the core-shell interface.
  • the material of the shell layer 2 contained in the composite electron transport material includes metal oxide, and the band gap of the metal oxide is wider (and also higher than) the band gap of the inorganic electron transport material.
  • the shell layer 2 is selected to contain a metal oxide with a relatively wide band gap, and it is used as the material of the shell layer 2 to coat the above-mentioned core body 1, which is also to coat the inorganic electron transport material particles, so that the metal oxide and the
  • the synergistic effect between inorganic electron transport materials enables metal oxides to effectively passivate the surface defects of inorganic electron transport materials, and can also increase the band gap of inorganic electron transport materials and improve the conduction band energy level of inorganic electron transport materials, thereby effectively
  • the exciton quenching of the light-emitting material such as quantum dots by the composite electron transport material of the embodiment of the present application is reduced, and the electron transport layer formed by the composite electron transport material of the embodiment of the present application and the light-emitting layer such as the quantum dot light
  • the light emitting diode containing the electron transport layer formed of the composite electron transport material of the embodiment of the present application can further be a blue light emitting diode with high luminous efficiency and long lifetime.
  • the metal oxide includes at least one of Yb 2 O 3 , La 2 O 3 , LaTi 2 O 7 , Nd 2 O 3 , ZrO 2 , and NiO.
  • the band gaps of these metal oxides are wider than those of inorganic electron transport materials, wherein the band gap of Yb 2 O 3 is 4.9 eV, the band gap of La 2 O 3 is 5.5 eV, and the band gap of LaTi 2 O 7 is 4.0 eV , Nd 2 O 3 has a band gap of 4.7 eV, ZrO 2 has a band gap of 5.0 eV, and NiO has a band gap of 3.5 eV.
  • the band gaps of these metal oxides are all wider than those of inorganic electron transport materials.
  • the band gap of ZnO is 3.2 eV, thereby enhancing its above-mentioned synergistic effect with core body 1.
  • the shell layer 2 may be at least one layer, such as one layer or more than two layers.
  • the band gap of the metal oxide contained in the shell layer 2 as described above is wider than the band gap of the inorganic electron transport material in the core body 1 .
  • the composite electron transport material can be specifically ZnO@Yb 2 O 3 , ZnO@La 2 O 3 , ZnO@LaTi 2 O 7 , ZnO@Nd 2 O 3 , ZnO@ZrO 2 , ZnO@NiO, wherein @ represents Coating, such as ZnO@Yb 2 O 3 means Yb 2 O 3 coats ZnO.
  • the shell layer 2 When the shell layer 2 is more than two, the shell layer 2 is covered by the first shell layer on the core body 1, the second shell layer on the first shell layer, and the third shell layer on the second shell layer to The core body 1 is covered in turn in the order of analogy, and the band gap gradient of each shell layer increases from the direction of the core body 1 to the outer surface of the shell layer 2 .
  • the band gap of the metal oxide contained in each shell layer as described above is wider than that of the inorganic electron transport material.
  • the shell layer 2 includes a first shell layer 21 and a second shell layer 22 , the first shell layer 21 covers the core body 1 , and the second shell layer 22 covers the first shell layer 21 .
  • the band gaps of the metal oxides contained in the first shell layer 21 and the second shell layer 22 are wider than that of the inorganic electron transport material, and the band gaps of the metal oxides contained in the second shell layer 22 are wider than those of the first shell layer 21 The band gap of the contained metal oxide.
  • the composite electron transport material may be ZnO@LaTi 2 O 7 @La 2 O 3 , ZnO@NiO@ZrO 2 , TiO 2 @LaTi 2 O 7 @La 2 O 3 , TiO 2 @NiO At least one of @ZrO 2 ; wherein @ represents coating, such as ZnO@LaTi 2 O 7 @La 2 O 3 represents La 2 O 3 as the second shell layer 22 and La 2 O 3 as the first shell layer 21 , LaTi 2 O 7 is coated by La 2 O 3 , and ZnO is coated by LaTi 2 O 7 .
  • the shell layer 2 is arranged in multiple layers and the band gap of each shell layer is controlled to increase gradually from the inside to the outside, that is, the band gap of the metal oxide contained in each shell layer is gradually increased from the inside to the outside, so that the shell layer 2 of the composite structure is increased. It can play a synergistic role with inorganic electron transport materials, further passivate the surface defects and conductivity of inorganic electron transport materials, and gradually increase the band gap and conduction band energy level of inorganic electron transport materials, so as to further improve the composite electron transport materials.
  • the exciton quenching of the light-reflecting material quantum dots further reduces the electron injection barrier between the electron transport layer formed by the composite electron transport material and the light-emitting layer such as the quantum dot light-emitting layer.
  • the thickness of the shell layer 2 is 1-6 nm.
  • the thickness of the first shell layer 21 is 1-3 nm; the thickness of the second shell layer 22 is 1-3 nm.
  • the composite electron transport material in the above embodiments can improve the band gap, conduction band energy level and conductivity of the inorganic electron transport material through the modification of the shell layer 2 and the core body 1, and effectively passivate the surface of the inorganic electron transport material.
  • the effect of defects can effectively improve the electron transport and injection efficiency of the composite electron transport material, reduce the exciton quenching phenomenon of the composite electron transport material on light-emitting materials such as quantum dots, and reduce the electron injection barrier between the electron transport layer and the light-emitting layer. Therefore, the light emitting diode containing the electron transport layer formed of the composite electron transport material of the embodiment of the present application can further be a blue light emitting diode with high luminous efficiency and long lifetime.
  • the embodiments of the present application also provide the above preparation method of the composite electron transport material. 1 and 2, the process flow of the preparation method of the composite electron transport material above is shown in FIG. 3, including the following steps:
  • S01 respectively providing inorganic electron transport material particles and a first precursor solution containing a first metal oxide precursor, and preparing the inorganic electron transport material into a core dispersion solution;
  • step S02 Mixing the core body dispersion solution and the first precursor solution in step S01 and performing the first heat treatment, so that the first metal oxide precursor undergoes a redox reaction, and the first metal oxide is grown in-situ on the surface of the inorganic electron transport material particles. shell layer to obtain composite particles.
  • the preparation method of the composite electron transport material further comprises the following steps:
  • step S04 performing mixing treatment and second heat treatment on the composite particle dispersion solution and the second precursor solution in step S03, so that the second metal oxide precursor undergoes a redox reaction, and the second metal oxide shell grows in situ on the surface of the composite particles Floor.
  • the inorganic electron transport material particles are the inorganic electron transport material particles of the core body 1 contained in the composite electron transport material above, and the first metal oxide precursor is the shell layer 2 contained in the composite electron transport material above.
  • the first metal oxide precursor may be capable of generating Yb 2 O 3 , La 2 O 3 , Corresponding metal salts of at least one of LaTi 2 O 7 , Nd 2 O 3 , ZrO 2 and NiO, specifically such as Yb(NO 3 ) 3 , La(NO 3 ) 3 , Ti(NO 3 ) 4 , Nd( NO 3 ) 3 , Zr(NO 3 ) 4 , Ni(NO 3 ) 2 and the like.
  • the solvent of the first precursor solution can be a solvent that is favorable for dissolving the first metal oxide precursor, such as but not only ethanol, dimethyl sulfoxide, and the like.
  • the concentration of the first metal oxide precursor is 1-100 mol/mL.
  • the solvent of the core body dispersion solution is a solvent capable of sufficiently dispersing the inorganic electron transport material particles and dissolving the first metal oxide precursor, such as but not only ethanol, dimethyl sulfoxide and the like.
  • the concentration of the inorganic electron transport material particles in the core body dispersion solution is 1-100 mg/mL.
  • the first heat treatment in step S02 is to heat the mixed solution, so that the first metal oxide precursor of the mixed solution is heated to undergo a redox reaction, and the first metal oxide is formed in situ on the surface of the inorganic electron transport material particles, thereby The surface of the inorganic electron transport material particles is coated in situ with the first metal oxide to form the shell layer 2 as shown in FIG. 1 or the shell layer 21 as shown in FIG. 2 .
  • the coated inorganic electron transport material The particles act as nucleus 1 as shown in Figures 1 and 2. Since the first metal oxide is oxidized by the wide band gap metal contained in the shell layer 2 of the composite electron transport material, the band gap of the first metal oxide generated by the redox reaction is wider than that of the inorganic electron transport material.
  • the mass ratio of the inorganic electron transport material particles to the first metal oxide precursor is 1:(0.2-3). Through the ratio range of the two, the thickness of the first metal oxide shell layer can be effectively controlled and adjusted.
  • the conditions of the first heat treatment are as follows: the temperature is 20-80° C., further 20-30° C., and the heat-treatment time at this temperature should be sufficient, for example, the time is 30-180 min.
  • the first metal oxide precursor can be fully oxidized to form a wide-bandgap metal oxide, which is uniformly coated on the surface of the inorganic electron transport material particles, and the effect of the first metal oxide on the inorganic electrons is improved.
  • the surface of the transport material particles is modified, so that the first metal oxide can passivate the surface defects of the inorganic electron transport material particles more effectively, and the conduction band energy level of the inorganic electron transport material is increased, thereby effectively reducing the effect of the composite electron transport material on luminescent materials such as quantum dots. Exciton quenching.
  • the generated first metal oxide can be doped on the surface of the inorganic electron transport material, which is also a doped film layer between the core body 1 and the cross section of the shell layer 2, so as to improve the core Conductivity and mobility to electrons of body 1.
  • a first ligand is also added to the mixed solution formed by the core dispersion solution and the first precursor solution, and by adding the first ligand, the metal ions contained in the first metal oxide precursor and The composite particles generated by the redox reaction are uniformly dispersed to avoid agglomeration, and the grown first metal oxide shell layer is more uniform.
  • the concentration of the first ligand in the mixed solution is 0.01-0.5 mg/mL.
  • the first ligand includes at least one of ethylene glycol, glycerol, ethanolamine, and tetramethylammonium hydroxide.
  • the second metal oxide precursor is a metal oxide with a wide band gap contained in the shell layer 2 contained in the above composite electron transport material as shown in FIG. 2 . Therefore, the second metal oxide precursor may be a corresponding metal salt capable of generating at least one of La 2 O 3 , ZrO 2 , Yb 2 O 3 , LaTi 2 O 7 , Nd 2 O 3 , NiO, then the second The metal oxide precursor can be a corresponding metal salt capable of generating at least one of La 2 O 3 , ZrO 2 , Yb 2 O 3 , LaTi 2 O 7 , Nd 2 O 3 , and NiO, specifically such as Yb(NO 3 ) 3 , La(NO 3 ) 3 , Ti(NO 3 ) 4 , Nd(NO 3 ) 3 , Zr(NO 3 ) 4 , Ni(NO 3 ) 2 and the like.
  • the band gap of the second metal oxide generated by the second metal oxide precursor should be wider (and also higher than
  • the solvent of the second precursor solution may be a solvent favorable for dissolving the second metal oxide precursor, such as ethanol, dimethyl sulfoxide and the like.
  • the concentration of the second metal oxide precursor is 1-100 mol/mL.
  • the solvent of the composite particle dispersion solution is a solvent capable of sufficiently dispersing the composite particles and dissolving the second metal oxide precursor, such as ethanol, dimethyl sulfoxide and the like.
  • the concentration of the composite particles in the dispersion of the composite particles is 1-100 mg/mL.
  • the effect of the second heat treatment in step S04 is the same as that of the first heat treatment in step S02, so that the second metal oxide precursor of the mixed solution is heated to undergo a redox reaction, and a second heat treatment is formed in situ on the surface of the first metal oxide shell layer.
  • Two metal oxides so that the second metal oxide coats the surface of the first metal oxide shell layer in situ to form the second shell layer 22 as shown in FIG. 2 .
  • the first metal oxide shell layer is The first shell layer 21 as shown in FIG. 2 . Since the second metal oxide is oxidized by the wide band gap metal contained in the second shell layer 22 of the above composite electron transport material, the band gap of the second metal oxide generated by the redox reaction is wider than that of the first metal oxide. Bandgap.
  • the mass ratio of the composite particles to the second metal oxide precursor is 1:(0.2-3). Through the ratio range of the two, the thickness of the second metal oxide shell layer can be effectively controlled and adjusted.
  • the conditions of the second heat treatment are as follows: the temperature is 20-80°C, further 60-80°C, and the heat treatment time at this temperature should be sufficient, for example, the time is 30-180min.
  • the second metal oxide precursor can be fully oxidized to form a wide-bandgap metal oxide, and the surface of the first metal oxide can be uniformly coated, thereby improving the effect of the second metal oxide on the first metal oxide.
  • a second ligand is also added to the mixed solution formed by the composite particle dispersion solution and the second precursor solution, and by adding the second ligand, the metal ions contained in the second metal oxide precursor and The composite particles of the grown second metal oxide shell layer are uniformly dispersed to avoid agglomeration, and the grown second metal oxide shell layer is more uniform.
  • the concentration of the second ligand in the mixed solution is 0.01-0.5 mg/mL.
  • the second ligand includes at least one of ethylene glycol, glycerol, ethanolamine, and tetramethylammonium hydroxide.
  • a third precursor solution containing a third metal oxide precursor and a fourth precursor solution containing a fourth metal oxide precursor may also be provided, and then the steps in step S04 are sequentially repeated, and the core The body 1 forms a multi-layer shell layer outwards in turn.
  • the third precursor solution is subjected to a third redox reaction to grow a third metal oxide shell layer in situ on the surface of the second metal oxide shell layer, and then Referring to the steps in S04, the fourth precursor solution is subjected to a fourth redox reaction to in-situ grow a fourth metal oxide shell layer on the surface of the third metal oxide shell layer.
  • steps S03 and S04 By repeating steps S03 and S04 in this way, at least two or more shell layers 2 are formed on the surface of the inorganic electron transport material particles in step S01, and from the core 1 to the outer surface of the shell layer 2, the band gap gradient of each shell layer is increase.
  • At least one shell layer 2 containing a wide-bandgap metal oxide is grown in-situ on the surface of the inorganic electron-transport material particles, which can make the wide-bandgap metal oxide and the inorganic electron transport material It can play a synergistic role in the above composite electron transport material of the present application, so that the surface defects of the inorganic electron transport material contained in the prepared composite electron transport material can be effectively passivated, and the band gap and conduction of the inorganic electron transport material can be increased.
  • the preparation conditions are easy to control, so that the prepared composite electron transport material has stable performance, high preparation efficiency and low cost.
  • the embodiments of the present application also provide a light emitting diode (electroluminescent diode).
  • the light emitting diode includes an electron transport layer.
  • the light-emitting diode also contains other layer structures necessary for the light-emitting diode, such as a light-emitting layer, an anode and a cathode, and a hole functional layer.
  • the material of the electron transport layer includes the composite electron transport material of the embodiments of the above text application.
  • the electron transport layer contained in the light-emitting diode can effectively reduce the quenching phenomenon of excitons in the light-emitting layer, and the electron injection barrier between the electron transport layer and the light-emitting layer is small. , so as to effectively improve the luminous efficiency, intensity and lifespan of light-emitting diodes, especially the luminous efficiency, intensity and lifespan of blue light-emitting diodes.
  • the light-emitting material of the light-emitting layer may be a quantum dot or an organic fluorescent light-emitting material
  • the light-emitting diode in the embodiment of the present application may be a quantum dot light-emitting diode (QLED) or an organic electroluminescent diode (OLED).
  • the material of the reflective layer can be a blue light-emitting material such as a blue quantum dot light-emitting material and/or a blue organic fluorescent light-emitting material materials, thereby effectively prolonging the luminous efficiency and luminous efficiency of the blue light emitting diode, thereby improving the commercial application value of the blue light emitting diode.
  • the light emitting diode in the embodiment of the present application may be a positive light emitting diode or an inversion light emitting diode.
  • the structure of the positive light emitting diode is shown in FIG. 4 , which includes a stacked structure of an anode 10 and a cathode 50 disposed opposite to each other, wherein the anode 10 can be stacked on the substrate 01 .
  • a light-emitting functional layer is laminated and bonded to the cathode 50 .
  • the light-emitting functional layer includes a light-emitting layer 30, a hole transport layer 20 and an electron transport layer 40. From the anode 10 to the cathode 50, the hole transport layer 20, the light-emitting layer 30, and the electron transport layer 40 are sequentially stacked.
  • a hole injection layer (not shown in FIG. 4 ) may also be provided between the hole transport layer 20 and the anode 10
  • an electron injection layer (not shown in FIG. 4 ) may be provided between the electron transport layer 40 and the cathode 50 .
  • FIG. 5 the structure of an inversion-type light-emitting diode is shown in FIG. 5 , which includes a stacked structure of an anode 10 and a cathode 50 arranged oppositely, wherein the cathode 50 can be stacked on the substrate 01, and the anode 50 can be stacked on the substrate 01.
  • a light-emitting functional layer is laminated and bonded between the cathode 10 and the cathode 50 .
  • the light-emitting functional layer includes a light-emitting layer 30, a hole transport layer 20 and an electron transport layer 40. From the anode 10 to the cathode 50, the hole transport layer 20, the light-emitting layer 30, and the electron transport layer 40 are sequentially stacked.
  • a hole injection layer (not shown in FIG. 5 ) may also be disposed between the hole transport layer 20 and the anode 10
  • an electron injection layer (not shown in FIG. 5 ) may be disposed between the electron transport layer 40 and the cathode 50 .
  • the surface of the cathode 50 is sequentially formed (the electron injection layer is formed first when there is an electron injection layer), the electron transport layer 40, the light-emitting layer 30, the hole transport layer 20, (When there is a hole injection layer, a hole injection layer is further formed on the surface of the hole transport layer 20 ), the anode 10 .
  • This embodiment provides a composite electron transport material and a preparation method thereof.
  • the composite electron transport material is the single-shell ZnO@Yb 2 O 3 core-shell structure particles shown in Figure 1, wherein the particle size of the core ZnO is averagely distributed between 2-5 nm, and the shell Yb 2 O 3 has an average particle size of 2-5 nm. Thickness is 1-3 nm.
  • the preparation method of ZnO@Yb 2 O 3 comprises the following steps:
  • step S3 In-situ generation of ZnO@Yb 2 O 3 : the mixed solution in step S2 was added with 25 mg of tetramethylammonium hydroxide, heated to 50°C for heat treatment to make the Yb 2 O 3 precursor undergo a redox reaction, Yb 2 O 3 shells were grown in situ on the surface of ZnO particles to obtain ZnO@Yb 2 O 3 .
  • This embodiment provides a composite electron transport material and a preparation method thereof.
  • the composite electron transport material is the single-shell ZnO@La 2 O 3 core-shell structure particles shown in Figure 1, wherein the particle size of the core ZnO is averagely distributed between 2-5 nm, and the particle size of the shell La 2 O 3 is between 2 and 5 nm. Thickness is 1-3 nm.
  • the preparation method of ZnO@La 2 O 3 comprises the following steps:
  • step S3 In-situ generation of ZnO@La 2 O 3 : add 25 mg of KOH to the mixed solution in step S2, heat it to 50 °C, and perform heat treatment to make the La 2 O 3 precursor undergo a redox reaction. The La 2 O 3 shell was grown in situ to obtain ZnO@La 2 O 3 .
  • This embodiment provides a composite electron transport material and a preparation method thereof.
  • the composite electron transport material is the single-shell ZnO@LaTi 2 O 7 core-shell structure particles shown in Figure 1, in which the particle size of the core ZnO is evenly distributed between 2-5 nm, and the shell layer LaTi 2 O 7 has an average particle size distribution of 2-5 nm. Thickness is 1-3 nm.
  • the preparation method of ZnO@LaTi 2 O 7 composite electron transport material includes the following steps:
  • step S3 In-situ generation of ZnO@LaTi 2 O 7 : heat the mixed solution in step S2, add 25 mg of tetramethylamine hydroxide, heat to 50 °C, and perform heat treatment to make the LaTi 2 O 7 precursor redox After the reaction, the LaTi 2 O 7 shell was grown in situ on the surface of the ZnO particles to obtain ZnO@LaTi 2 O 7 .
  • This embodiment provides a composite electron transport material and a preparation method thereof.
  • the composite electron transport material is the core-shell structure particles of double-shell ZnO@LaTi 2 O 7 @La 2 O 3 shown in Figure 2, wherein the particle size of the core ZnO is evenly distributed between 2-5 nm; the first shell The layer is LaTi 2 O 7 and its thickness is 1-3 nm; the second shell layer is La 2 O 3 and its thickness is 1-3 nm.
  • the preparation method of the ZnO@LaTi 2 O 7 @La 2 O 3 composite electron transport material includes the following steps:
  • La 2 O 3 precursor solution mix and stir La(NO 3 ) 3 and ethanol aqueous solution to prepare a 150 mg/mL solution;
  • step S3 In-situ generation of ZnO@LaTi 2 O 7 : add 25 mg of tetramethylammonium hydroxide to the mixed solution in step S2, heat it to 50 °C, and perform heat treatment to make the LaTi 2 O 7 precursor undergo a redox reaction , the LaTi 2 O 7 shell was grown in situ on the surface of ZnO particles to obtain ZnO@LaTi 2 O 7 ;
  • the composite electron transport material is the core-shell structure particles of double-shell ZnO@NiO@ZrO 2 as shown in Figure 2, wherein the particle size of the core ZnO is evenly distributed between 2-5 nm; the first shell is NiO, and Its thickness is 1-3 nm; the second shell is ZrO 2 and its thickness is 1-3 nm.
  • the preparation method of ZnO@NiO@ZrO 2 composite electron transport material includes the following steps:
  • NiO precursor solution Mix and stir Ni(NO 3 ) 2 and ethanol aqueous solution to prepare a 0.2-300 mg/mL solution;
  • This comparative example provides a doped zinc oxide (ZnO) material.
  • the doped zinc oxide is doped with Yb.
  • the material structure is shown in FIG. 6 , wherein the Yb doping ratio is 5% on average.
  • the precursor of Yb and the precursor of ZnO are directly mixed, and then synthesized by the existing one-step method.
  • ZnO zinc oxide
  • 3-10 mmol of Zn(CH3COO) 2 and 25 mg of tetramethylammonium hydroxide in ethanol or dimethyl sulfoxide solution (50 mL) were mixed and stirred at 50 °C. Heating for 30-180 min, after centrifugal cleaning, the particle size of ZnO nanoparticles with an average distribution of 2-5 nm in ethanol solution was obtained.
  • the lattice analysis of doped zinc oxide provided in Comparative Example 11 shows that the doping metal is randomly assigned to each ZnO nanoparticle, and the doping concentration of each ZnO nanoparticle is inconsistent, as shown in Figure 6(A) With doping, Fig. 6(B) is not doped, the doping position is uncontrollable, and the doping is not uniform, which will affect the consistency of the mobility and conductivity of the ZnO nanoparticle film; and there are a large number of defect states on the surface of ZnO, which will affect the QD Exciton quenching is generated; in addition, the surface energy of ZnO is large, which will further grow and mature, which is unstable, and the feasibility of mass production is low.
  • the present comparative example provides a zinc oxide (ZnO)-containing composition material, which is a mixture of ZnO and Yb 2 O 3 .
  • ZnO zinc oxide
  • FIG. 7 A schematic diagram of the composition is shown in FIG. 7 .
  • the composition is prepared by firstly preparing ZnO and Yb 2 O 3 , and then mixing them in a ratio of 100:5.
  • the QLED light-emitting diode is a positive quantum dot light-emitting diode, which includes ITO(15 nm)/Ag(110 nm)/ITO(55 nm)/PEDOT: PSS hole injection layer (30 nm)/TFB hole transport layer (30 nm) nm)/ZnCdSeSZnS quantum dot light-emitting layer (25 nm)/ZnO@Yb 2 O 3 electron transport layer (30 nm)/Ag cathode (15 nm).
  • “/" expresses the connection relationship of the layer structure of the layered bonding.
  • the ZnO@Yb 2 O 3 electron transport layer is the core-shell structure particles of ZnO@Yb 2 O 3 provided in Example 11 above.
  • S1 prepare a first electrode on a transparent substrate, and the first electrode can choose ITO/Ag/ITO as a total reflection electrode;
  • a hole injection layer is prepared on the first electrode by spin coating, and the material of the hole injection layer is PEDOT:PSS AI4083; spin coating speed of 3000-5000 rpm, heat treatment at 150 °C for 15 min under air.
  • the hole transport layer was prepared by spin coating on the hole injection layer, the hole transport material was TFB, the concentration of TFB solution was 6-10 mg/mL, the spin coating speed was 3000-5000 rpm, and 150 °C under N2 Heat treatment for 20min;
  • the blue quantum dot (QD) light-emitting layer was prepared by spin coating on the hole transport layer.
  • the QD material was a ZnCdSeS/ZnS QD solution with a concentration of 10-30 mg/mL, and the spin coating speed was 3000-5000 rpm; N 2 Heat treatment at 80°C-100°C for 5 min;
  • the electron transport layer is prepared by spin coating on the QD light-emitting layer.
  • the electron transport material is the core-shell structure particles of ZnO@Yb 2 O 3 prepared in Example 11.
  • the solution concentration is 20-40 mg/mL, optional Spin coating speed is 3000-5000 rpm; heat treatment temperature is 80 °C-100 °C, time is 30 min;
  • S6 prepare a second electrode on the electron transport layer, the optional electrode material is Ag, the thickness is 80-100 nm, and the vacuum evaporation process is used to prepare, and the plating rate is 1 angstroms per second.
  • This embodiment provides a QLED light-emitting diode and a manufacturing method thereof.
  • the structure and preparation method of the QLED light-emitting diode are the same as those of the QLED light-emitting diode in Example 21, except that the material of the electron transport layer is the ZnO@La 2 O 3 core-shell structure particles prepared in Example 12.
  • This embodiment provides a QLED light-emitting diode and a manufacturing method thereof.
  • the structure and preparation method of the QLED light-emitting diode are the same as those of the QLED light-emitting diode in Example 21, except that the material of the electron transport layer is the ZnO@LaTi 2 O 7 core-shell structure particles prepared in Example 13.
  • This embodiment provides a QLED light-emitting diode and a manufacturing method thereof.
  • the structure and preparation method of the QLED light-emitting diode are the same as those of the QLED light-emitting diode in Example 21, except that the material of the electron transport layer is the ZnO@LaTi 2 O 7 @La 2 O 3 core-shell structure particles prepared in Example 14.
  • This embodiment provides a QLED light-emitting diode and a manufacturing method thereof.
  • the structure and preparation method of the QLED light-emitting diode are the same as those of the QLED light-emitting diode in Example 21, except that the material of the electron transport layer is the ZnO@NiO@ZrO 2 core-shell structure particles prepared in Example 15.
  • This comparative example provides a QLED light-emitting diode and a preparation method thereof.
  • the structure and preparation method of the QLED light-emitting diode of this comparative example are the same as those of the QLED light-emitting diode in Example 21.
  • the difference is that the material of the electron transport layer is the doped zinc oxide material prepared in Comparative Example 11.
  • This comparative example provides a QLED light-emitting diode and a preparation method thereof.
  • the structure and preparation method of the QLED light-emitting diode of this comparative example are the same as those of the QLED light-emitting diode in Example 21.
  • the difference is that the material of the electron transport layer is the zinc oxide-containing composition material prepared in Comparative Example 12.

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Abstract

本申请公开了一种复合电子传输材料及其制备方法和发光二极管。复合电子传输材料包括核体和包覆于核体的至少一层的壳层，核体的材料为无机电子传输材料，壳层的材料包括金属氧化物，且金属氧化物的带隙宽于无机电子传输材料的带隙。复合电子传输材料通过壳层对和核体包覆改性，提高无机电子传输材料的带隙和导带能级以及导电性。

Description

复合电子传输材料及其制备方法和发光二极管
本申请要求于2020年12月30日在中国专利局提交的、申请号为202011627735.9、申请名称为“复合电子传输材料及其制备方法和发光二极管”的中国申请专利的优先权。
技术领域
本申请属于光电技术领域，尤其涉及一种复合电子传输材料及其制备方法和发光二极管。
 背景技术
发光二极管如量子点电致发光二极管（QLED）具有发光波长在可见光范围连续可调、发光线宽窄在15-20 nm范围、发光色饱和度高、发光色域可达 BT2020标准色域的90%等优势引起了人们广泛关注。另外，量子点作为发光材料为无机纳米晶体，制备成器件后，理论寿命较长、器件稳定性好，且反应时间快、工作电压低、对比度高、可制成大尺寸和柔性显示面板，成为下一代显示技术的热门。
目前，发光二极管特别是QLED在100cd m -2时，T50>2,000,000h小时，而蓝色QLED在100 cd m -2时，T50>10000小时，蓝色量子点器件的寿命尚不能满足商业化需求。蓝色QLED的工作寿命很短，是因为量子点和电子传输层（ETL）之间的II型结构，激发蓝色量子点（QD）中的电子容易在ETL中空间电荷积累和导致器件的工作电压升高。因此，与一些非常稳定的红色量子点器件不同，红色量子点器件的寿命主要受空穴传输层的缓慢退化，而导致了蓝色QLED寿命的降低是从QD-ETL交界处的快速降解。因此进一步提高电子传输层的导电率和禁带宽度，获得高效电子传输材料，是提高蓝色量子点QLED工作寿命的先决条件。
虽然目前也有尝试提高电子传输层导电率和禁带宽度的报道，但是在实际应用中发现并不理想。
 技术问题
本申请提供一种复合电子传输材料及其制备方法，以及含有复合电子传输材料的发光二极管，以解决现有电子传输材料禁带宽度相对窄而导致电子传输和注入效率低以及电子传输层与发光层之间注入势垒高的技术问题。
 技术解决方案
本申请一方面提供了一种复合电子传输材料。本申请复合电子传输材料包括核体和包覆于核体的至少一层的壳层，核体的材料为无机电子传输材料，壳层的材料包括金属氧化物，且金属氧化物的带隙宽于无机电子传输材料的带隙。
进一步地，金属氧化物包括Yb 2O 3、La 2O 3、LaTi 2O 7、Nd 2O 3、ZrO 2、NiO中的至少一种。
进一步地，无机电子传输材料包括ZnO、TiO 2中的至少一种。
进一步地，壳层的厚度为1-6 nm。
进一步地，核体粒径为2-5 nm。
进一步地，壳层包括两层以上，按照第一壳层包覆于核体、第二壳层包覆于第一壳层的顺序依次包覆核体，且由核体至壳层外表面的方向，各壳层的带隙梯度增大。
更进一步地，第一壳层的材料包括LaTi 2O 7、NiO中的至少一种。
更进一步地，第一壳层的厚度为1-3 nm。
更进一步地，第二壳层材料包括La 2O 3、ZrO 2中的至少一种。
更进一步地，第二壳层的厚度为1-3 nm。
具体地，壳层为两层，且复合电子传输材料为ZnO@LaTi 2O 7@La 2O 3、ZnO@NiO@ZrO 2、TiO 2@LaTi 2O 7@La 2O 3、TiO 2@NiO@ZrO 2中的至少一种；其中，@表述包覆。
进一步地，核体与壳层的界面形成有掺杂薄层。
本申请的另一方面，提供了一种复合电子传输材料的制备方法。本申请复合电子传输材料的制备方法包括如下步骤：
分别提供无机电子传输材料颗粒和含有第一金属氧化物前驱体的第一前驱体溶液，并将无机电子传输材料配制成核体分散溶液；
将核体分散溶液与第一前驱体溶液进行混合处理和第一热处理，使得第一金属氧化物前驱体发生氧化还原反应，在无机电子传输材料颗粒表面原位生长第一金属氧化物壳层，获得复合颗粒；
其中，第一金属氧化物壳层中的第一金属氧化物的带隙宽于无机电子传输材料的带隙。
进一步地，第一热处理的温度为20-80℃。
进一步地，核体分散溶液与第一前驱体溶液形成的混合溶液中，无机电子传输材料颗粒与第一金属氧化物前驱体的质量比1：（0.2-3）。
进一步地，核体分散溶液与第一前驱体溶液形成的混合溶液中还添加有第一配体，且第一配体在混合溶液中的浓度为0.01-0.5 mg/mL。
进一步地，第一金属氧化物前驱体包括生成Yb 2O 3、La 2O 3、LaTi 2O 7、Nd 2O 3、ZrO 2、NiO中的至少一种的相应金属盐。
更进一步地，第一配体包括乙二醇、甘油、乙醇胺、四甲基氢氧化铵中的至少一种。
进一步地，还包括如下步骤：
提供含有第二金属氧化物前驱体的第二前驱体溶液；
将复合颗粒配制成复合颗粒分散溶液；
将复合颗粒分散溶液与第二前驱体溶液进行混合处理和第二热处理，使得第二金属氧化物前驱体发生氧化还原反应，在复合颗粒表面原位生长第二金属氧化物壳层；
其中，第二金属氧化物壳层中的第二金属氧化物的带隙宽于第一金属氧化物的带隙。
更进一步地，第二热处理的温度为20-80℃。
更进一步地，复合颗粒分散溶液与第二前驱体溶液形成的混合溶液中，复合颗粒与第二金属氧化物前驱体的质量比1：（0.2-3）。
更进一步地，复合颗粒分散溶液与第二前驱体溶液形成的混合溶液中还添加有第二配体，且第二配体在混合溶液中的浓度为0.01-0.5 mg/mL。
更进一步地，第二金属氧化物前驱体包括生成La 2O 3、ZrO 2、Yb 2O 3、LaTi 2O 7、Nd 2O 3、NiO中的至少一种的相应金属盐。
更进一步地，第二配体包括乙二醇、甘油、乙醇胺、四甲基氢氧化铵中的至少一种。
本申请的再一方面，提供了一种发光二极管。本申请发光二极管包括电子传输层，电子传输层的材料包括本申请复合电子传输材料或由本申请复合电子传输材料的制备方法制备的复合电子传输材料。
进一步地，发光二极管为QLED和OLED。
进一步地，发光二极管为蓝色发光二极管。
与现有技术相比，本申请具有以下的技术效果：
本申请复合电子传输材料采用带隙相对较宽的金属氧化物作为壳层包覆带隙相对较窄的作为核体无机电子传输材料，实现金属氧化物与无机电子传输材料之间的增效作用，使得金属氧化物有效钝化无机电子传输材料表面缺陷，并在无机电子传输材料颗粒包覆界面形成掺杂的导电膜层，同时增大了无机电子传输材料的带隙，提高了无机电子传输材料的导带能级，从而有效提高了输送复合电子传输材料的导电性能和对电子传输和注入能力，有效降低了复合电子传输材料对发光材料如量子点的激子淬灭，降低了由复合电子传输材料形成的电子传输层与发光层如量子点发光层之间的电子注入势垒，从而有效提高含有由复合电子传输材料形成的电子传输层的发光二极管进一步可以是蓝色发光二极管的发光效率和寿命。
本申请复合电子传输材料的制备方法在无机电子传输材料颗粒表面原位生长至少一层含宽带隙的金属氧化物的壳层，一方面能够使得宽带隙金属氧化物与无机电子传输材料之间能够起到上述本申请复合电子传输材料中的增效作用，使得制备的复合电子传输材料所含的无机电子传输材料表面缺陷得以有效钝化，增大无机电子传输材料的带隙和导带能级以及导电性；另一方面，其制备条件易控，使得制备的复合电子传输材料性能稳定，而且制备的效率高，成本低。
本申请发光二极管由于其所含的电子传输层的材料为本申请复合电子传输材料，因此，电子传输层具有高的电子传输和注入效率，能够有效降低对发光层中的激子淬没现象和降低电子传输层与发光层之间的电子注入势垒，提高发光二极管的发光效率和寿命。
 附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例或示范性技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其它的附图。
图1是本申请实施例含单层壳层的复合电子传输材料的结构示意图；
图2是本申请实施例含双层壳层的复合电子传输材料的结构示意图；
图3是本申请实施例复合电子传输材料的制备方法工艺流程示意图；
图4是本申请实施例正型发光二极管的结构示意图；
图5是本申请实施例反型发光二极管的结构示意图；
图6是对比例11提供的掺杂氧化锌的结构示意图；
图7是对比例12提供的含氧化锌组合物的结构示意图。
 本发明的实施方式
为了使本申请要解决的技术问题、技术方案及有益效果更加清楚明白，以下结合实施例，对本申请进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本申请，并不用于限定本申请，基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
一方面，本申请实施例提供了一种复合电子传输材料。复合电子传输材料为核壳结构，如图1和图2所示，其包括核体1和包覆于核体1的壳层2。
其中，复合电子传输材料所含核体1的材料为无机电子传输材料。该无机电子传输材料可以是常规的无机电子传输材料，如在一实施例中，该无机电子传输材料包括ZnO、TiO 2中的至少一种。
而且通过控制核体1的直径能够有效发挥无机电子传输材料的对电子传输作用，在一实施例中，该核体1为纳米颗粒，如粒径为2-5 nm。该范围的直径的无机电子传输材料具有较好的结晶性，并利于壳层的包覆和核壳界面掺杂。
复合电子传输材料所含壳层2的材料包括金属氧化物，且金属氧化物的带隙宽于（也既是高于）无机电子传输材料的带隙。这样，壳层2选用含有带隙相对较宽的金属氧化物，且将其作为壳层2的材料并包覆上述核体1，也既是包覆无机电子传输材料颗粒，能够实现金属氧化物与无机电子传输材料之间的增效作用，使得金属氧化物有效钝化无机电子传输材料表面缺陷，还能增大无机电子传输材料的带隙，提高无机电子传输材料的导带能级，从而有效降低了本申请实施例复合电子传输材料对发光材料如量子点的激子淬灭，并能够降低由本申请实施例复合电子传输材料形成的电子传输层与发光层如量子点发光层之间的电子注入势垒。而且在核体1和壳层2的界面可形成掺杂薄层，掺杂可控，且可以保证每一个核体1表层能够均匀掺杂，可提高核体1的导电性和电子迁移率。因此，含有由本申请实施例复合电子传输材料形成的电子传输层的发光二极管进一步可以是蓝色发光二极管具有高的发光效率和长的寿命。在具体实施例中，金属氧化物包括Yb 2O 3、La 2O 3、LaTi 2O 7、Nd 2O 3、ZrO 2、NiO中的至少一种。该些金属氧化物的带隙均相对无机电子传输材料的带隙宽，其中，Yb 2O 3的带隙4.9eV、La 2O 3的带隙5.5 eV、LaTi 2O 7的带隙4.0 eV、Nd 2O 3的带隙4.7 eV、ZrO 2的带隙5.0 eV、NiO的带隙3.5 eV，该些金属氧化物的带隙均宽于无机电子传输材料的带隙，如均高于上述ZnO的带隙3.2eV，从而提高其与核体1的上述增效作用。
另外，壳层2可以是至少一层，如可以是一层或者两层以上。当壳层2为如图1所示的一层时，如上述的壳层2中所含金属氧化物的带隙是宽于核体1中无机电子传输材料的带隙。这样，复合电子传输材料可以具体是ZnO@Yb 2O 3、ZnO@La 2O 3、ZnO@LaTi 2O 7、ZnO@Nd 2O 3、ZnO@ZrO 2、ZnO@NiO，其中，@表述包覆，如ZnO@Yb 2O 3表示Yb 2O 3包覆ZnO。
当壳层2为两层以上时，壳层2是按照第一壳层包覆于核体1、第二壳层包覆于第一壳层、第三壳层包覆于第二壳层以此类推的顺序依次包覆核体1，且由核体1至壳层2外表面的方向，各壳层的带隙梯度增大。但是依然需要满足如上述的各壳层中所含金属氧化物的带隙宽于无机电子传输材料的带隙。具体的如图2所示，壳层2包括第一壳层21和第二壳层22，第一壳层21包覆于核体1，第二壳层22包覆于第一壳层21，而且第一壳层21和第二壳层22所含金属氧化物的带隙宽于无机电子传输材料的带隙，第二壳层22所含金属氧化物的带隙宽于第一壳层21所含金属氧化物的带隙。因此，在具体实施例中，复合电子传输材料可以是ZnO@LaTi 2O 7@La 2O 3、ZnO@NiO@ZrO 2、TiO 2@LaTi 2O 7@La 2O 3、TiO 2@NiO@ZrO 2中的至少一种；其中，@表述包覆，如ZnO@LaTi 2O 7@La 2O 3表示La 2O 3作为第二壳层22，La 2O 3作为第一壳层21，La 2O 3包覆LaTi 2O 7，LaTi 2O 7包覆ZnO。这样，将壳层2设置多层并控制各壳层的带隙由内向外梯度增加，也既是各壳层中所含金属氧化物的带隙由内向外梯度增加，使得复合结构的壳层2能够与无机电子传输材料之间的发挥增效作用，进一步钝化无机电子传输材料表面缺陷以及导电性，逐渐提高无机电子传输材料的带隙和导带能级，以进一步提高复合电子传输材料对反光材料量子点的激子淬灭，进一步降低由复合电子传输材料形成的电子传输层与发光层如量子点发光层之间的电子注入势垒。
在上述各实施例的基础上，一实施例中，壳层2的厚度为1-6 nm。壳层2为如图2所示的两层以上的复合结构时，第一壳层21的厚度为1-3 nm；第二壳层22的厚度为1-3 nm。通过优化壳层2的厚度，提高壳层2对核体1的带隙改性作用，提高无机电子传输材料的带隙和导带能级和有效钝化无机电子传输材料表面缺陷作用。
因此，上述各实施例中复合电子传输材料通过壳层2对和核体1的改性作用，提高无机电子传输材料的带隙和导带能级以及导电性，有效钝化无机电子传输材料表面缺陷作用，能够有效提高复合电子传输材料的电子传输和注入效率，降低复合电子传输材料对发光材料如量子点的激子淬灭现象和降低电子传输层与发光层之间的电子注入势垒。因此，含有由本申请实施例复合电子传输材料形成的电子传输层的发光二极管进一步可以是蓝色发光二极管具有高的发光效率和长的寿命。
相应地，本申请实施例还提供了上文复合电子传输材料的制备方法。结合图1和图2，上文复合电子传输材料的制备方法工艺流程如图3所示，包括如下步骤：
S01：分别提供无机电子传输材料颗粒和含有第一金属氧化物前驱体的第一前驱体溶液，并将无机电子传输材料配制成核体分散溶液；
S02：将步骤S01中核体分散溶液与第一前驱体溶液进行混合处理和第一热处理，使得第一金属氧化物前驱体发生氧化还原反应，在无机电子传输材料颗粒表面原位生长第一金属氧化物壳层，获得复合颗粒。
在进一步实施例中，复合电子传输材料的制备方法还包括如下步骤：
S03：提供含有第二金属氧化物前驱体的第二前驱体溶液和将复合颗粒配制成复合颗粒分散溶液；
S04：将步骤S03中复合颗粒分散溶液与第二前驱体溶液进行混合处理和第二热处理，使得第二金属氧化物前驱体发生氧化还原反应，在复合颗粒表面原位生长第二金属氧化物壳层。
其中，步骤S01中无机电子传输材料颗粒为上文复合电子传输材料所含核体1的无机电子传输材料颗粒，第一金属氧化物前驱体为上文复合电子传输材料所含壳层2具体如图1所示壳层2或图2所示壳层21所含的宽带隙金属氧化物的前驱体，因此，第一金属氧化物前驱体可以是能够生成Yb 2O 3、La 2O 3、LaTi 2O 7、Nd 2O 3、ZrO 2、NiO中的至少一种的相应金属盐，具体的如Yb(NO 3) 3、La(NO 3) 3、Ti(NO 3) 4、Nd(NO 3) 3、Zr(NO 3) 4、Ni(NO 3) 2等。
第一前驱体溶液的溶剂可以是利于第一金属氧化物前驱体溶解的溶剂，如可以但不仅仅是乙醇、二甲基亚砜等。在一实施例中，在第一前驱体溶液中，第一金属氧化物前驱体的浓度为1-100mol/mL。
一实施例中，核体分散溶液的溶剂是能够充分分散无机电子传输材料颗粒和能够溶解第一金属氧化物前驱体的溶剂，如可以但不仅仅是乙醇、二甲基亚砜等。在一实施例中，在核体分散溶液中，无机电子传输材料颗粒的浓度为1-100 mg/mL。
步骤S02中的第一热处理是对混合溶液进行加热处理，使得混合溶液的第一金属氧化物前驱体受热发生氧化还原反应，在无机电子传输材料颗粒的表面原位生成第一金属氧化物，从而使得第一金属氧化物原位包覆在无机电子传输材料颗粒的表面，形成如图1所示的壳层2或如图2所示的壳层21，此时被包覆的无机电子传输材料颗粒作为如图1和图2所示的核体1。由于第一金属氧化物为上文复合电子传输材料壳层2所含的宽带隙金属氧化，因此，氧化还原反应生成的第一金属氧化物的带隙宽于无机电子传输材料的带隙。
一实施例中，步骤S02核体分散溶液与第一前驱体溶液形成的混合溶液中，无机电子传输材料颗粒与第一金属氧化物前驱体的质量比1：（0.2-3）。通过两者的比例范围，能够有效控制和调节生成第一金属氧化物壳层的厚度。
另一实施例中，第一热处理的条件为：温度20-80℃，进一步为20-30℃，该温度下热处理时间应该是充分的，如时间为30-180min。通过对第一热处理条件控制和优化，能够使得第一金属氧化物前驱体充分被氧化生成宽带隙金属氧化物，且均匀包覆在无机电子传输材料颗粒表面，提高第一金属氧化物对无机电子传输材料颗粒表面进行修饰，使得第一金属氧化物更有效钝化无机电子传输材料颗粒表面缺陷，提高无机电子传输材料的导带能级，从而有效降低复合电子传输材料对发光材料如量子点的激子淬灭。同时，通过原位生长的方式，使得生成的第一金属氧化物能够在无机电子传输材料表面进行掺杂，也既是在核体1和壳层2截面之间形成掺杂膜层，从而提高核体1的导电性和对电子的迁移率。
进一步实施例中，在核体分散溶液与第一前驱体溶液形成的混合溶液中还添加有第一配体，通过添加第一配体，使得第一金属氧化物前驱体所含的金属离子和氧化还原反应生成的复合颗粒分散均匀，避免发生团聚现象，而且生长的第一金属氧化物壳层更加均匀。在一实施例中，该第一配体在混合溶液中的浓度为0.01-0.5 mg/mL。具体实施例中，该第一配体包括乙二醇、甘油、乙醇胺、四甲基氢氧化铵中的至少一种。
步骤S03中第二金属氧化物前驱体为上文复合电子传输材料所含壳层2如图2所示壳层22所含宽带隙的金属氧化物。因此，第二金属氧化物前驱体可以是能够生成La 2O 3、ZrO 2、Yb 2O 3、LaTi 2O 7、Nd 2O 3、NiO中的至少一种的相应金属盐，那么第二金属氧化物前驱体可以是能够生成La 2O 3、ZrO 2、Yb 2O 3、LaTi 2O 7、Nd 2O 3、NiO中的至少一种的相应金属盐，具体的如Yb(NO 3) 3、La(NO 3) 3、Ti(NO 3) 4、Nd(NO 3) 3、Zr(NO 3) 4、Ni(NO 3) 2等。但是，第二金属氧化物前驱体生成的第二金属氧化物的带隙应该是宽于（也既是高于）步骤S01中第一金属氧化物前驱体生成的第一金属氧化物的带隙。
第二前驱体溶液的溶剂可以是利于第二金属氧化物前驱体溶解的溶剂，如可以是乙醇、二甲基亚砜等。在一实施例中，在第二前驱体溶液中，第二金属氧化物前驱体的浓度为1-100mol/mL。
一实施例中，复合颗粒分散溶液的溶剂是能够充分分散复合颗粒和能够溶解第二金属氧化物前驱体的溶剂，如可以是乙醇，二甲基亚砜等。在一实施例中，在复合颗粒分散中，复合颗粒的浓度为1-100 mg/mL。
步骤S04中的第二热处理作用与步骤S02中的第一热处理作用相同，使得混合溶液的第二金属氧化物前驱体受热发生氧化还原反应，在第一金属氧化物壳层的表面原位生成第二金属氧化物，从而使得第二金属氧化物原位包覆在第一金属氧化物壳层的表面，形成如图2所示的第二壳层22，此时第一金属氧化物壳层为如图2所示的第一壳层21。由于第二金属氧化物为上文复合电子传输材料的第二壳层22所含的宽带隙金属氧化，因此，氧化还原反应生成的第二金属氧化物的带隙宽于第一金属氧化物的带隙。
一实施例中，步骤S04中复合颗粒分散溶液与第二前驱体溶液形成的混合溶液中，复合颗粒与第二金属氧化物前驱体的质量比1：（0.2-3）。通过两者的比例范围，能够有效控制和调节生成第二金属氧化物壳层的厚度。
另一实施例中，第二热处理的条件为：温度20-80℃，进一步为60-80℃，该温度下热处理时间应该是充分的，如时间为30-180min。通过对第二热处理条件控制和优化，能够使得第二金属氧化物前驱体充分被氧化生成宽带隙金属氧化物，且均匀包覆在第一金属氧化物表面，提高第二金属氧化物对第一金属氧化物壳层表面的包覆。
进一步实施例中，在复合颗粒分散溶液与第二前驱体溶液形成的混合溶液中还添加有第二配体，通过添加第二配体，使得第二金属氧化物前驱体所含的金属离子和生长第二金属氧化物壳层的复合颗粒分散均匀，避免发生团聚现象，而且生长的第二金属氧化物壳层更加均匀。在一实施例中，该第二配体在混合溶液中的浓度为0.01-0.5 mg/mL。具体实施例中，该第二配体包括乙二醇、甘油、乙醇胺、四甲基氢氧化铵中的至少一种。
当然，在步骤S04之后，还可以提供含有第三金属氧化物前驱体的第三前驱体溶液、第四金属氧化物前驱体的第四前驱体溶液，然后依次重复步骤S04中的步骤，由核体1向外依次形成多层壳层，如参照S04中的步骤将第三前驱体溶液进行第三氧化还原反应在第二金属氧化物壳层表面原位生长第三金属氧化物壳层，接着参照S04中的步骤将第四前驱体溶液进行第四氧化还原反应在第三金属氧化物壳层表面原位生长第四金属氧化物壳层。通过这样重复步骤S03和S04使得在步骤S01中的无机电子传输材料颗粒表面形成至少两层以上的壳层2，而且由核体1至壳层2外表面的方向，各壳层的带隙梯度增大。
因此，上述各实施例中复合电子传输材料的制备方法在无机电子传输材料颗粒表面原位生长至少一层含宽带隙金属氧化物的壳层2，能够使得宽带隙金属氧化物与无机电子传输材料之间能够起到上述本申请复合电子传输材料中的增效作用，使得制备的复合电子传输材料所含的无机电子传输材料表面缺陷得以有效钝化，增大无机电子传输材料的带隙和导带能级以及导电性能；与此同时，其制备条件易控，使得制备的复合电子传输材料性能稳定，而且制备的效率高，成本低。
再一方面，基于复合电子传输材料及其制备方法，本申请实施例还提供了一种发光二极管（电致发光二极管）。发光二极管包括电子传输层。当然发光二极管还含有发光二极管必要的其他层结构，如发光层、阳极和阴极以及空穴功能层等。其中，该电子传输层的材料包含上文本申请实施例复合电子传输材料。这样，基于上文复合电子传输材料的优点，则发光二极管所含的电子传输层能够有效降低对发光层中的激子淬没现象，而且电子传输层与发光层之间的电子注入势垒小，从而有效提高发光二极管的发光效率、强度和寿命，特别是提高蓝色发光二极管的发光效率、强度和寿命。
另外，根据发光二极管的电子传输层所含的上文复合电子传输材料和其如上文的作用，其不仅可以激发量子点也可以激发有机荧光材料的发光效率。因此，发光层的发光材料可以是量子点也可以是有机荧光发光材料，那么本申请实施例发光二极管可以是量子点发光二极管（QLED）或有机电致发光二极管（OLED）。而且同样基于发光二极管的电子传输层所含的上文复合电子传输材料和其如上文的作用，反光层的材料可以是蓝色发光材料如蓝色量子点发光材料和/或蓝色有机荧光发光材料，从而有效延长蓝色发光二极管的发光效率和发光效率，从而提高蓝色发光二极管的商业应用价值。
其次，根据发光二极管的结构设置，本申请实施例发光二极管可以正型发光二极管，也可以是反型发光二极管。
如在一种实施方式中，正型发光二极管的结构如图4所示，其包括相对设置的阳极10和阴极50的层叠结构，其中，阳极10可以层叠结合在衬底01上，在阳极10和阴极50之间层叠结合有发光功能层。发光功能层包括发光层30和空穴传输层20以及电子传输层40，由阳极10至阴极50的方向，空穴传输层20、发光层30、电子传输层40依次层叠，进一步地，在空穴传输层20与阳极10之间还可以设置空穴注入层（图4未显示），在电子传输层40与阴极50之间还可以设置电子注入层（图4未显示）。
那么，在制备如图4所示正型发光二极管时，在阳极10的表面依次形成（空穴传注入层，可选地）、空穴传输层20，发光层30、电子传输层40、（或进一步形成空穴注入层）、阴极50。
在另一种实施方式中，反型结构发光二极管的结构如图5所示，其包括相对设置的阳极10和阴极50的层叠结构，其中，阴极50可以层叠结合在衬底01上，在阳极10和阴极50之间层叠结合有发光功能层。发光功能层包括发光层30和空穴传输层20以及电子传输层40，由阳极10至阴极50的方向，空穴传输层20、发光层30、电子传输层40依次层叠，进一步地，在空穴传输层20与阳极10之间还可以设置空穴注入层（图5未显示），在电子传输层40与阴极50之间还可以设置电子注入层（图5未显示）。
那么，在制备如图5所示反型发光二极管时，在阴极50的表面依次形成（有电子注入层时先形成电子注入层）、电子传输层40、发光层30、空穴传输层20、（有空穴注入层时，在空穴传输层20表面进一步形成空穴注入层）、阳极10。
为使本申请上述实施细节和操作能清楚地被本领域技术人员理解，以及本申请实施例复合电子传输材料、空穴注入复合材料、空穴传输复合材料和发光二极管及其制备方法的进步性能显著的体现，以下通过多个实施例来举例说明上述技术方案。
1. 复合电子传输材料及其制备方法实施例
实施例11
本实施例提供一种复合电子传输材料及其制备方法。复合电子传输材料为图1所示的单壳层的ZnO@Yb 2O 3的核壳结构颗粒，其中，核体ZnO的粒径平均分布2-5 nm之间，壳层Yb 2O 3的厚度为1-3 nm。
ZnO@Yb 2O 3的制备方法包括如下步骤：
S1. 配制Yb 2O 3前驱体溶液：将Yb(NO 3) 3和乙醇溶液混合搅拌配置成150 mg/mL溶液；
S2. 配制含Yb 2O 3前驱体和氧化锌（ZnO）纳米颗粒的混合溶液：将50 mg/mL的ZnO纳米粒子乙醇溶液和配置好的Yb 2O 3前驱体溶液按照质量比1：1.5混合；
S3. 原位生成ZnO@Yb 2O 3：将步骤S2中的混合溶液，并加入25 mg的四甲基氢氧化铵，加热至50℃进行热处理使得Yb 2O 3前驱体发生氧化还原反应，在ZnO颗粒表面原位生长Yb 2O 3壳层，获得ZnO@Yb 2O 3。
实施例12
本实施例提供一种复合电子传输材料及其制备方法。复合电子传输材料为图1所示的单壳层的ZnO@La 2O 3的核壳结构颗粒，其中，核体ZnO的粒径平均分布2-5 nm之间，壳层La 2O 3的厚度为1-3 nm。
ZnO@La 2O 3的制备方法包括如下步骤：
S1. 配制La 2O 3前驱体溶液：将La(NO 3) 3和二甲基亚砜混合搅拌配置成150 mg/mL溶液；
S2. 配制含La 2O 3前驱体和氧化锌（ZnO）纳米颗粒的混合溶液：将50 mg/mL的ZnO纳米粒子乙醇溶液和配置好的La 2O 3前驱体溶液按照质量比1：1.5混合；
S3. 原位生成ZnO@La 2O 3：将步骤S2中的混合溶液，并加入25 mg的KOH，加热至50 ℃，进行热处理使得La 2O 3前驱体发生氧化还原反应，在ZnO颗粒表面原位生长La 2O 3壳层，获得ZnO@La 2O 3。
实施例13
本实施例提供一种复合电子传输材料及其制备方法。复合电子传输材料为图1所示的单壳层的ZnO@LaTi 2O 7的核壳结构颗粒，其中，核体ZnO的粒径平均分布2-5 nm之间，壳层LaTi 2O 7的厚度为1-3 nm。
ZnO@LaTi 2O 7复合电子传输材料的制备方法包括如下步骤：
S1. 配制LaTi 2O 7前驱体溶液：将摩尔比为1:2 的La(NO 3) 3和Ti(NO 3) 4和乙醇水溶液混合搅拌配置成150 mg/mL溶液；
S2. 配制含LaTi 2O 7前驱体和氧化锌（ZnO）纳米颗粒的混合溶液：将50 mg/mL的ZnO纳米粒子乙醇溶液和配置好的LaTi 2O 7前驱体溶液按照质量比1：1.5混合；
S3. 原位生成ZnO@ LaTi 2O 7：将步骤S2中的混合溶液加热，并加入25 mg的四甲基氢氧化胺，加热至50 ℃，进行热处理使得LaTi 2O 7前驱体发生氧化还原反应，在ZnO颗粒表面原位生长LaTi 2O 7壳层，获得ZnO@LaTi 2O 7。
实施例14
本实施例提供一种复合电子传输材料及其制备方法。复合电子传输材料为图2所示的双壳层ZnO@LaTi 2O 7@La 2O 3的核壳结构颗粒，其中，核体ZnO的粒径平均分布2-5 nm之间；第一壳层为LaTi 2O 7，且其厚度为1-3 nm；第二壳层为La 2O 3，且其厚度为1-3 nm。
ZnO@LaTi 2O 7@La 2O 3复合电子传输材料的制备方法包括如下步骤：
S1. 配制LaTi 2O 7前驱体溶液：将摩尔比为1:2 的La(NO 3) 3和Ti(NO 3) 4和乙醇水溶液混合搅拌配置成150 mg/mL溶液；
配制La 2O 3前驱体溶液：将La(NO 3) 3和乙醇水溶液混合搅拌配置成150 mg/mL溶液；
S2. 配制含LaTi 2O 7前驱体和氧化锌（ZnO）纳米颗粒的混合溶液：将50 mg/mL的ZnO纳米粒子乙醇溶液和配置好的LaTi 2O 7前驱体溶液按照质量比1：1.5混合；
S3. 原位生成ZnO@ LaTi 2O 7：将步骤S2中的混合溶液，并加入25 mg的四甲基氢氧化胺，加热至50 ℃，进行热处理使得LaTi 2O 7前驱体发生氧化还原反应，在ZnO颗粒表面原位生长LaTi 2O 7壳层，获得ZnO@LaTi 2O 7；
S4. 原位生成ZnO@LaTi 2O 7@La 2O 3：将步骤S1中配制La 2O 3前驱体溶液与含有步骤S3中生成的ZnO@LaTi 2O 7分散溶液进行混合处理，并于加热并加入25 mg的四甲基氢氧化胺，加热至50℃，进行热处理使得La 2O 3前驱体发生氧化还原反应，在LaTi 2O 7壳层表面原位生长La 2O 3壳层，获得ZnO@LaTi 2O 7@La 2O 3。
实施例15
本实施例提供一种复合电子传输材料及其制备方法。复合电子传输材料为图2所示的双壳层ZnO@NiO@ZrO 2的核壳结构颗粒，其中，核体ZnO的粒径平均分布2-5 nm之间；第一壳层为NiO，且其厚度为1-3 nm；第二壳层为ZrO 2，且其厚度为1-3 nm。
ZnO@NiO@ZrO 2复合电子传输材料的制备方法包括如下步骤：
S1. 配制NiO前驱体溶液：将Ni(NO 3) 2和乙醇水溶液混合搅拌配置成0.2-300 mg/mL溶液；
配制ZrO 2前驱体溶液：将Zr(NO 3) 4和乙醇水溶液混合搅拌配置成0.2-300 mg/mL溶液；
S2. 配制含NiO前驱体和氧化锌（ZnO）纳米颗粒的混合溶液：将50 mg/mL的ZnO纳米粒子乙醇溶液和配置好的NiO前驱体溶液按照质量比1：1.5混合；
S3. 原位生成ZnO@NiO：将步骤S2中的混合溶液，并加入25 mg的四甲基氢氧化胺，加热至50℃，进行热处理使得NiO前驱体发生氧化还原反应，在ZnO颗粒表面原位生长NiO壳层，获得ZnO@NiO；
S4. 原位生成ZnO@NiO@ZrO 2：将步骤S1中配制ZrO 2前驱体溶液与含有步骤S3中生成的ZnO@NiO分散溶液进行混合处理，并加入0.1-50 mg的四甲基氢氧化胺，加热至50℃，进行热处理使得ZrO 2前驱体发生氧化还原反应，在NiO壳层表面原位生长ZrO 2壳层，获得ZnO@NiO@ZrO 2。
对比例11
本对比例提供一种掺杂氧化锌（ZnO）材料，该掺杂氧化锌由Yb掺杂氧化锌，材料结构如图6所示，其中，Yb掺杂比例平均为5%。该掺杂氧化锌是将Yb的前驱体与ZnO的前驱体直接混合，然后采用现有的一步法合成。
氧化锌（ZnO）纳米粒子的合成方法，将3-10mmol的Zn（CH3COO） 2和25 mg的四甲基氢氧化铵的乙醇或二甲基亚砜溶液（50mL）混合搅拌并在50 ℃下加热30-180 min，经离心清洗后粒径获得平均分布2-5 nm的ZnO纳米粒子乙醇溶液。
经对对比例11提供的掺杂氧化锌的晶格分析得知，掺杂金属被随机分配到每一个ZnO纳米粒子中，其中每个ZnO纳米粒子的掺杂浓度不一致，如图6（A）有掺杂，图6（B）无掺杂，掺杂位置不可控，掺杂不均匀，会影响ZnO纳米粒子薄膜迁移率和导电性的一致性；且ZnO表面存在大量缺陷态，将对QD产生激子淬灭；另外ZnO表面能较大，将进一步生长和熟化，不稳定，量产可行性较低。
对比例12
本对比例提供一种含氧化锌（ZnO）组合物材料，该含氧化锌（ZnO）组合物为ZnO和Yb 2O 3的混合物。组合物的示意图如图7所示。该组合物是先分别制备ZnO和Yb 2O 3，然后按照100：5的比例进行混合处理。
经对对比例12提供的含氧化锌组合物材料分析得知，在ZnO和Yb 2O 3的混合物中虽然含有Yb 2O 3纳米粒子，但是不能有效改善ZnO纳米粒子的迁移率和导电性，不能提高ZnO的导带能级，不能改善ZnO表面的缺陷态以及不能降低ZnO表面能和不能提高ZnO纳米粒子的稳定性。
2. 发光二极管及其制备方法实施例
实施例21
本实施例提供一种QLED发光二极管及其制备方法。QLED发光二极管为正型量子点发光二极管，其包括ITO(15 nm)/Ag(110 nm)/ITO(55 nm)/PEDOT：PSS空穴注入层（30 nm）/TFB空穴传输层（30 nm）/ZnCdSeSZnS量子点发光层（25 nm）/ZnO@Yb 2O 3电子传输层（30 nm）/Ag阴极（15 nm）。其中，“/”表述层叠结合的层结构连接关系。ZnO@Yb 2O 3电子传输层为上述实施例11中提供的ZnO@Yb 2O 3的核壳结构颗粒。
本实施例QLED的制备方法包括如下步骤：
S1：在透明衬底上制备第一电极，该第一电极可选择ITO/Ag/ITO为全反射电极；
S2：在第一电极上采用旋涂方法制备空穴注入层，空穴注入层材料为PEDOT：PSS  AI4083；旋涂转速为3000-5000 rpm，空气下150℃热处理15 min。
S3：在空穴注入层上采用旋涂方法制备空穴传输层，空穴传输材料为TFB，TFB溶液浓度为6-10 mg/mL，旋涂转速为3000-5000 rpm，N 2下150℃热处理20min；
S4：在空穴传输层上采用旋涂方法制备蓝色量子点（QD）发光层，QD材料为ZnCdSeS/ZnS QD溶液浓度10-30 mg/mL，旋涂转速为3000-5000 rpm；N 2下80℃-100℃热处理5 min；
S5：在QD发光层上采用旋涂方法制备电子传输层，电子传输材料为实施例11制备的ZnO@Yb 2O 3的核壳结构颗粒，溶液浓度为20-40 mg/mL，可选的旋涂转速为3000-5000 rpm；热处理温度为80 ℃-100 ℃，时间为30 min；
S6：在电子传输层上制备第二电极，可选的电极材料为Ag，厚度为80-100 nm，采用真空蒸镀工艺制备，镀率为1埃每秒。
实施例22
本实施例提供一种QLED发光二极管及其制备方法。QLED发光二极管的结构和制备方法均与实施例21中QLED发光二极管相同，不同在于电子传输层的材料为实施例12制备的ZnO@La 2O 3的核壳结构颗粒。
实施例23
本实施例提供一种QLED发光二极管及其制备方法。QLED发光二极管的结构和制备方法均与实施例21中QLED发光二极管相同，不同在于电子传输层的材料为实施例13制备的ZnO@LaTi 2O 7的核壳结构颗粒。
实施例24
本实施例提供一种QLED发光二极管及其制备方法。QLED发光二极管的结构和制备方法均与实施例21中QLED发光二极管相同，不同在于电子传输层的材料为实施例14制备的ZnO@LaTi 2O 7@La 2O 3的核壳结构颗粒。
实施例25
本实施例提供一种QLED发光二极管及其制备方法。QLED发光二极管的结构和制备方法均与实施例21中QLED发光二极管相同，不同在于电子传输层的材料为实施例15制备的ZnO@NiO@ZrO 2的核壳结构颗粒。
对比例21
本对比例提供一种QLED发光二极管及其制备方法。本对比例QLED发光二极管的结构和制备方法均与实施例21中QLED发光二极管相同。其中，不同在于电子传输层的材料为对比例11制备的掺杂氧化锌材料。
对比例22
本对比例提供一种QLED发光二极管及其制备方法。本对比例QLED发光二极管的结构和制备方法均与实施例21中QLED发光二极管相同。其中，不同在于电子传输层的材料为对比例12制备的含氧化锌组合物材料。
量子点发光二极管相关光电性能测试
分别测试实施例21至实施例25、对比例21至对比例22制备的QLED器件分别进行如下表1中相关光电性能测试。测试结果如表1中所示：
表1
项目 组别 EQE LT95@1000nit
实施例21 18% 150h
实施例22 15% 120h
实施例23 20% 200h
实施例24 12% 50h
实施例25 16% 80h
对比例21 8% 30h
对比例22 5% 20h
从上表1测试结果可见，实施例21至实施例25测试的EQE和LT95@1000nit明显优于对比例21和对比例21，从而说明本申请实施例11至实施例15提供的核壳结构复合电子传输材料的带隙和导带能级以及导电性相对于对比例21和对比例21的明显提高，氧化锌纳米晶粒表面的缺陷被钝化，提高了对电子的传输和注入能力，有效激发了量子点的发光效率。
以上所述仅为本申请的较佳实施例而已，并不用以限制本申请，凡在本申请的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本申请的保护范围之内。

Claims (20)

  1. 一种复合电子传输材料，其中，包括核体和包覆于所述核体的壳层，所述核体的材料为无机电子传输材料，所述壳层的材料包括金属氧化物，且所述金属氧化物的带隙宽于无机电子传输材料的带隙。
  2. 如权利要求1所述的复合电子传输材料，其中，所述金属氧化物包括Yb 2O 3、La 2O 3、LaTi 2O 7、Nd 2O 3、ZrO 2、NiO中的至少一种。
  3. 如权利要求1所述的复合电子传输材料，其中，所述无机电子传输材料包括ZnO、TiO 2中的至少一种。
  4. 如权利要求1至3任一项所述的复合电子传输材料，其中，所述壳层的厚度为1-6 nm；和/或
    所述核体粒径为2-5 nm。
  5. 如权利要求1-4任一项所述的复合电子传输材料，其中，所述壳层包括两层以上，按照第一壳层包覆于所述核体、第二壳层包覆于所述第一壳层的顺序依次包覆所述核体，且由所述核体至所述壳层外表面的方向，各壳层的带隙梯度增大。
  6. 如权利要求5所述的复合电子传输材料，其中，所述第一壳层的材料包括LaTi 2O 7、NiO中的至少一种；和/或
    所述第二壳层的材料包括La 2O 3、ZrO 2中的至少一种。
  7. 如权利要求6所述的复合电子传输材料，其中，所述壳层为两层，且复合电子传输材料为ZnO@LaTi 2O 7@La 2O 3、ZnO@NiO@ZrO 2、TiO 2@LaTi 2O 7@La 2O 3、TiO 2@NiO@ZrO 2中的至少一种；其中，@表述包覆。
  8. 如权利要求5所述的复合电子传输材料，其中，所述第一壳层的厚度为1-3 nm；和/或
    所述第二壳层的厚度为1-3 nm。
  9. 如权利要求1-8任一项所述的复合电子传输材料，其中，所述核体与所述壳层的界面形成有掺杂薄层。
  10. 一种复合电子传输材料的制备方法，其中，包括如下步骤：
    分别提供无机电子传输材料颗粒和含有第一金属氧化物前驱体的第一前驱体溶液，并将所述无机电子传输材料配制成核体分散溶液；
    将所述核体分散溶液与所述第一前驱体溶液进行混合处理和第一热处理，使得所述第一金属氧化物前驱体发生氧化还原反应，在所述无机电子传输材料颗粒表面原位生长第一金属氧化物壳层，获得复合颗粒；
    其中，所述第一金属氧化物壳层中的第一金属氧化物的带隙宽于所述无机电子传输材料的带隙。
  11. 根据权利要求10所述的制备方法，其中，所述第一热处理的温度为20-80 ℃。
  12. 根据权利要求10或11所述的制备方法，其中，所述核体分散溶液与所述第一前驱体溶液形成的混合溶液中，所述无机电子传输材料颗粒与第一金属氧化物前驱体的质量比1：（0.2-3）。
  13. 根据权利要求10-12任一项所述的制备方法，其中，所述核体分散溶液与所述第一前驱体溶液形成的混合溶液中还添加有第一配体，且所述第一配体在所述混合溶液中的浓度为0.01-0.5 mg/mL。
  14. 根据权利要求10-13任一项所述的制备方法，其中，所述第一金属氧化物前驱体包括生成Yb 2O 3、La 2O 3、LaTi 2O 7、Nd 2O 3、ZrO 2、NiO中的至少一种的相应金属盐。
  15. 根据权利要求11-14任一项所述的制备方法，其中，所述第一配体包括乙二醇、甘油、乙醇胺、四甲基氢氧化铵中的至少一种。
  16. 根据权利要求10-14任一项所述的制备方法，其中，还包括如下步骤：
    提供含有第二金属氧化物前驱体的第二前驱体溶液；
    将所述复合颗粒配制成复合颗粒分散溶液；
    将所述复合颗粒分散溶液与所述第二前驱体溶液进行混合处理和第二热处理，使得所述第二金属氧化物前驱体发生氧化还原反应，在所述复合颗粒表面原位生长第二金属氧化物壳层；
    其中，所述第二金属氧化物壳层中的第二金属氧化物的带隙宽于所述第一金属氧化物的带隙。
  17. 根据权利要求16所述的制备方法，其中，所述第二热处理的温度为20-80 ℃；和/或
    所述复合颗粒分散溶液与所述第二前驱体溶液形成的混合溶液中，所述复合颗粒与第二金属氧化物前驱体的质量比1：（0.2-3）；和/或
    所述复合颗粒分散溶液与所述第二前驱体溶液形成的混合溶液中还添加有第二配体，且所述第二配体在所述混合溶液中的浓度为0.01-0.5 mg/mL；和/或
    所述第二金属氧化物前驱体包括生成La 2O 3、ZrO 2、Yb 2O 3、LaTi 2O 7、Nd 2O 3、NiO中的至少一种的相应金属盐。
  18. 根据权利要求16所述的制备方法，其中，所述第二配体包括乙二醇、甘油、乙醇胺、四甲基氢氧化铵中的至少一种。
  19. 一种发光二极管，包括电子传输层，其中，所述电子传输层的材料包括权利要求1-9任一项所述的复合电子传输材料或由权利要求10-18任一项所述的制备方法制备的复合电子传输材料。
  20. 根据权利要求19所述的发光二极管，其中，所述发光二极管为QLED和OLED；和/或
    所述发光二极管为蓝色发光二极管。
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