WO2022143961A1 - 量子点发光二极管及其制备方法 - Google Patents

量子点发光二极管及其制备方法 Download PDF

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WO2022143961A1
WO2022143961A1 PCT/CN2021/143433 CN2021143433W WO2022143961A1 WO 2022143961 A1 WO2022143961 A1 WO 2022143961A1 CN 2021143433 W CN2021143433 W CN 2021143433W WO 2022143961 A1 WO2022143961 A1 WO 2022143961A1
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zinc oxide
transport layer
electron transport
quantum dot
dot light
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PCT/CN2021/143433
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English (en)
French (fr)
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吴龙佳
张天朔
李俊杰
郭煜林
童凯
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Tcl科技集团股份有限公司
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Priority claimed from CN202011640396.8A external-priority patent/CN114695825A/zh
Priority claimed from CN202011639878.1A external-priority patent/CN114695742A/zh
Priority claimed from CN202011640040.4A external-priority patent/CN114695824A/zh
Priority claimed from CN202011637282.8A external-priority patent/CN114695821A/zh
Priority claimed from CN202011636998.6A external-priority patent/CN114695719A/zh
Priority claimed from CN202011640060.1A external-priority patent/CN114695743A/zh
Application filed by Tcl科技集团股份有限公司 filed Critical Tcl科技集团股份有限公司
Priority to US18/270,609 priority Critical patent/US20240083764A1/en
Publication of WO2022143961A1 publication Critical patent/WO2022143961A1/zh

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Definitions

  • the present application relates to the field of display technology, and in particular, to a quantum dot light-emitting diode and a preparation method thereof.
  • Quantum dots are a class of nanomaterials composed of a small number of atoms, whose radii are usually smaller than or close to the exciton Bohr radius, exhibiting remarkable quantum confinement effects and unique optical properties.
  • quantum dot light-emitting diodes Quantum Dot Light Emitting Diode, QLED
  • QLED Quantum Dot Light Emitting Diode
  • Quantum dot light-emitting diodes have the characteristics of high luminous efficiency, controllable luminous color, high color purity, good device stability, and can be used for flexible applications. They have great application prospects in display technology, solid-state lighting and other fields.
  • QLED mainly includes cathode, anode and quantum dot light-emitting layer.
  • one or more layers of hole transport and injection layer, hole transport layer, electron transport layer, and electron injection layer are introduced into QLED as functional layers.
  • As an electron transport layer material commonly used in QLEDs zinc oxide has a good energy level matching relationship with the cathode and the quantum dot light-emitting layer, which significantly reduces the injection barrier of electrons from the cathode to the quantum dot light-emitting layer.
  • the deep valence band energy level can play the function of effectively blocking holes.
  • zinc oxide material also has excellent electron transport ability, and its electron mobility is as high as 10 -3 cm 2 /V ⁇ S. All these characteristics make zinc oxide material the first material for electron transport layer in quantum dot light-emitting diode devices, which significantly improves the stability and luminous efficiency of the device.
  • One of the objectives of the embodiments of the present application is to provide a quantum dot light-emitting diode and a method for preparing the same.
  • a quantum dot light-emitting diode comprising an anode and a cathode disposed opposite to each other, a quantum dot light-emitting layer disposed between the anode and the cathode, and a quantum dot light-emitting layer disposed between the quantum dot light-emitting layer and the cathode.
  • electron transport layer between
  • the electron transport layer includes a first electron transport layer, and the first electron transport layer is a zinc oxide film with surface hydroxyl groups greater than or equal to 0.6; or
  • the electron transport layer contains zinc oxide, and at least part of the surface of the zinc oxide contains amine ligands and/or carboxyl ligands having 8 to 18 carbon atoms.
  • the electron transport layer is the first electron transport layer
  • the zinc oxide in the first electron transport layer is metal-doped or metal-undoped zinc oxide.
  • the electron transport layer is the first electron transport layer
  • the zinc oxide forming the first electron transport layer is undoped zinc oxide or metal-doped zinc oxide.
  • the electron transport layer further includes a second electron transport layer, and the second electron transport layer is disposed on a surface of the first electron transport layer on one side of the first electron transport layer close to the cathode or the quantum dot light-emitting layer , and the second electron transport layer is a zinc oxide film or metal-doped zinc oxide with a surface hydroxyl amount of less than or equal to 0.4.
  • the electron transport layer consists of the first electron transport layer and the second electron transport layer, and the second electron transport layer is closer to the quantum than the first electron transport layer Click on the light-emitting layer.
  • the electron transport layer includes n thin film stack units consisting of a first electron transport layer and the second electron transport layer, wherein n is greater than or equal to 2.
  • the electron transport layer further includes a third electron transport layer.
  • the third electron transport layer is a zinc oxide film with surface hydroxyl groups greater than or equal to 0.6.
  • the third electron transport layer is disposed on a side surface of the second electron transport layer away from the first electron transport layer, and the second electron transport layer has a surface hydroxyl group of less than or equal to 0.4 zinc oxide film.
  • the third electron transport layer is a zinc oxide thin film with surface hydroxyl groups less than or equal to 0.4.
  • the second electron transport layer is a zinc oxide film with surface hydroxyl groups less than or equal to 0.4
  • the third electron transport layer is disposed on the first electron transport layer away from the second electron transport layer one side surface of the layer;
  • the second electron transport layer is a metal-doped zinc oxide film
  • the third electron transport layer is disposed between the second electron transport layer and the first electron transport layer.
  • the third electron transport layer is a metal-doped zinc oxide film.
  • the third electron transport layer is disposed on a side surface of the second electron transport layer away from the first electron transport layer.
  • the second electron transport layer is a zinc oxide thin film with surface hydroxyl groups less than or equal to 0.4.
  • the third electron transport layer is selected from zinc oxide films whose surfaces contain amine ligands and/or carboxyl ligands with 8-18 carbon atoms on the surface, and the second electron transport layer is bonded to On one side surface of the first electron transport layer, the third electron transport layer is bonded to the side surface of the second electron transport layer away from the first electron transport layer.
  • the amine ligand and/or carboxyl ligand having 8-18 carbon atoms is selected from at least one of caprylic acid, octylamine, dodecanoic acid, dodecylamine, oleic acid, and oleylamine kind.
  • the surface contains amine ligands and/or carboxyl ligands with a carbon number of 8-18 selected from amino ligands and/or carboxyl ligands with a carbon number of 8-12, so The molar ratio of the amine ligand and/or carboxyl ligand having 8-12 carbon atoms and zinc oxide is 1:1 to 10:1; or
  • the surface contains amine ligands and/or carboxyl ligands with a carbon number of 8-18 selected from amino ligands and/or carboxyl ligands with a carbon number of 13-18, and the carbon number is 13
  • the molar ratio of the amine ligand and/or carboxyl ligand of -18 to zinc oxide is 1:4 to 5:1.
  • the electron transport layer has a thickness of 10-100 nm.
  • the thickness of the zinc oxide thin film with surface hydroxyl groups greater than or equal to 0.6 is 10-30 nm.
  • the thickness of the first electron transport layer is 10-80 nm.
  • the thickness of the zinc oxide thin film with the surface hydroxyl amount less than or equal to 0.4 is 20-60 nm.
  • the thickness of the metal-doped zinc oxide thin film is 10-30 nm.
  • the quantum dots in the quantum dot light-emitting layer are selected from mononuclear quantum dots or core-shell quantum dots, and the core and shell compounds of the quantum dots are each independently selected from CdS, CdSe, CdTe, ZnO, ZnS, ZnSe, ZnTe, GaAs, GaP, GaSb, HgS, HgSe, HgTe, InAs, InP, InSb, AlAs, AlP, CuInS, CuInSe, and core-shell quantum dots or alloy structure quantum dots formed by the above substances at least one of; and/or
  • the material of the anode includes at least one of zinc oxide, indium oxide, tin oxide, indium tin oxide, indium zinc oxide, and fluorine-doped tin oxide.
  • the material of the cathode is Ag, Al, Au, Mg, Ca, Yb, Ba or alloys thereof.
  • the quantum dot light-emitting diode further includes a hole functional layer disposed in the anode and the corresponding quantum dot light-emitting layer, and the hole functional layer at least includes a hole injection layer and a hole transport layer at least one of them.
  • the material of the hole injection layer is selected from at least one of poly(ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), HTL-1, HTL-2 .
  • the material of the hole transport layer is selected from 4,4'-N,N'-dicarbazolyl-biphenyl, poly[(9,9'-dioctylfluorene-2,7 -diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(4-butylphenyl-diphenylamine), 4,4' , at least one of 4'-tris(N-carbazolyl)-triphenylamine, poly(N-vinylcarbazole) and derivatives thereof.
  • the material of the hole injection layer is selected from at least one of poly(ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), HTL-1, HTL-2 ;
  • the material of the hole transport layer is selected from 4,4'-N,N'-dicarbazolyl-biphenyl, poly[(9,9'-dioctylfluorene-2,7-diyl)- co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(4-butylphenyl-diphenylamine), 4,4',4'-triphenylamine At least one of (N-carbazolyl)-triphenylamine, poly(N-vinylcarbazole) and derivatives thereof.
  • the doping metal in the metal-doped zinc oxide film is selected from at least one of Mg 2+ and Mn 2+ ; or the doping metal in the metal-doped zinc oxide film is selected from At least one of Al 3+ , Y 3+ , La 3+ , Li + , Gd 3+ , Zr 4+ , Ce 4+ .
  • the doping content of the doping metal is as follows:
  • the doping metal is Mg 2+
  • the doping molar concentration of Mg 2+ in the metal-doped zinc oxide film is 0.1%-35%
  • the doping metal is Mn 2+
  • the doping molar concentration of Mn 2+ in the metal-doped zinc oxide film is 0.1%-30%
  • the doping metal is Al 3+
  • the doping molar concentration of Al 3+ in the metal-doped zinc oxide film is 0.1%-15%
  • the doping molar concentration of Y 3+ in the metal-doped zinc oxide film is 0.1%-10%;
  • the doping metal is Gd 3+
  • the doping molar concentration of Gd 3+ in the metal-doped zinc oxide film is 0.01%-8%
  • the doping metal is Zr 4+
  • the doping molar concentration of Zr 4+ in the metal-doped zinc oxide film is 0.1%-45%
  • the doping metal is Ce 4+
  • the doping molar concentration of Ce 4+ in the metal-doped zinc oxide film is 0.1%-10%.
  • a first method for preparing a quantum dot light emitting diode the quantum dot light emitting diode comprises an anode and a cathode arranged oppositely, a quantum dot light emitting layer arranged between the anode and the cathode, and a quantum dot light emitting layer arranged on the quantum dot light emitting layer
  • An electron transport layer between the cathode and the cathode wherein the electron transport layer includes a first electron transport layer, and the first electron transport layer is a zinc oxide film with a surface hydroxyl group greater than or equal to 0.6;
  • the preparation method of the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 includes:
  • the zinc oxide colloid solution is formed on the prefabricated device substrate on which the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 is to be prepared, and the solvent is removed to obtain the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6.
  • the alkali in the first alkali solution is selected from alkalis with K b >10 -1 , and the number of times of the cleaning treatment is less than or equal to 2 times;
  • the base with K b >10 -1 is selected from at least one of potassium hydroxide, sodium hydroxide, and lithium hydroxide, and the base with K b ⁇ 10 -1 is selected from TMAH, ammonia water , at least one of ethanolamine and ethylenediamine.
  • the reaction solvent is selected from at least one of water, organic alcohol, organic ether, and sulfone.
  • the reaction solvent is selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and DMSO.
  • the zinc oxide film with surface hydroxyl groups greater than or equal to 0.6 is a metal-doped zinc oxide film, and the zinc salt solution further contains doped metal ions.
  • the doping concentration of the doping metal ions is as follows:
  • the doped metal ion is Mg 2+
  • the molar content of Mg 2+ in the zinc salt solution accounts for 0.1% to 35% of the total molar amount of metal ions
  • the doped metal ion is Mn 2+
  • the molar content of Mn 2+ in the zinc salt solution accounts for 0.1% to 30% of the total molar amount of metal ions
  • the doped metal ion is Al 3+
  • the molar content of Al 3+ in the zinc salt solution accounts for 0.1%-15% of the total molar amount of metal ions
  • the molar content of Y 3+ in the zinc salt solution accounts for 0.1%-10% of the total molar amount of metal ions
  • the doped metal ion is La 3+
  • the molar content of La 3+ in the zinc salt solution accounts for 0.1%-7% of the total molar amount of metal ions
  • the doped metal ion is Li +
  • the molar content of Li + in the zinc salt solution accounts for 0.1% to 45% of the total molar amount of metal ions
  • the molar content of Gd 3+ in the zinc salt solution accounts for 0.01% to 8% of the total molar amount of metal ions;
  • the molar content of Zr 4+ in the zinc salt solution accounts for 0.1% to 45% of the total molar amount of metal ions
  • the molar content of Ce 4+ in the zinc salt solution accounts for 0.1%-10% of the total molar amount of metal ions.
  • the addition amount of the zinc salt solution and the first lye solution satisfies: the product of the molar amount of the metal ion and the valence and the hydrogen
  • the molar ratio of oxygen ions is 0.75:1 to 1.25:1.
  • a second method for preparing a quantum dot light emitting diode comprises the quantum dot light emitting diode comprising an anode and a cathode arranged oppositely, a quantum dot light emitting layer arranged between the anode and the cathode, and An electron transport layer between the quantum dot light-emitting layer and the cathode, wherein the electron transport layer includes a first electron transport layer, and the zinc oxide surface forming the first electron transport layer contains carbon atoms with a number of Amine ligands and/or carboxyl ligands of 8-18;
  • a zinc oxide colloidal solution is prepared by a solution method; wherein, the zinc oxide surface in the zinc oxide solution is Combined with amine ligands and/or carboxyl ligands with a carbon number of 8-18;
  • a zinc oxide colloid solution is formed on the prefabricated device substrate on which the first electron transport layer is to be prepared, and the solvent is removed to prepare the first electron transport layer.
  • the zinc salt solution, the lye solution and the amine ligand and/or carboxyl ligand having a carbon number of 8-18 are mixed and reacted to prepare an amino ligand having a carbon number of 8-18 on the surface.
  • the zinc oxide nanoparticles are dissolved to obtain a zinc oxide colloidal solution.
  • the step of preparing zinc oxide colloidal solution by solution method includes:
  • the zinc salt solution is mixed and reacted with the lye solution, and the amino ligand and/or carboxyl ligand with the carbon number of 8-18 are added in the reaction process, and the preparation surface is combined with the carbon number of 8-18.
  • the zinc oxide nanoparticles are dissolved to obtain a zinc oxide colloidal solution.
  • the step of preparing zinc oxide colloidal solution by solution method includes:
  • Zinc oxide nanoparticles that are amine ligands and/or carboxyl ligands of 8-18;
  • the zinc oxide nanoparticles are dissolved to obtain a zinc oxide colloidal solution.
  • the step of preparing zinc oxide colloidal solution by solution method includes:
  • the reaction is performed for 10 minutes to 2 hours.
  • the amine ligand and/or carboxyl ligand having 8-18 carbon atoms is a ligand solution, and the concentration of the ligand solution is 0.2-0.4 mmol/L.
  • the addition amount of the amino ligands and/or carboxyl ligands with a carbon number of 8-18 satisfies: the amino ligands and/or carboxyl ligands with a carbon number of 8-18
  • the molar ratio of the body to the zinc salt in the zinc salt solution is 1:1-10:1.
  • the number of carbon atoms of the amino ligands and/or carboxyl ligands is 8-12, and the addition amount of the amino ligands and/or carboxyl ligands satisfies: the amino ligands and /or the molar ratio of the carboxyl ligand to the zinc salt in the zinc salt solution is 4:1 to 10:1;
  • the number of carbon atoms of the amino ligand and/or the carboxyl ligand is 13-18, and the addition amount of the amino ligand and/or the carboxyl ligand satisfies: the amino ligand and/or the carboxyl ligand and the The molar ratio of the zinc salt in the zinc salt solution is 1:1-5:1.
  • the amine ligand and/or carboxyl ligand having 8-18 carbon atoms is a ligand solution, and the concentration of the ligand solution is 0.05-0.1 mmol/L.
  • the number of carbon atoms of the amino ligand and/or the carboxyl ligand is 13-18, and the addition amount of the amino ligand and/or the carboxyl ligand satisfies: the amino ligand and/or the carboxyl ligand and the The molar ratio of the zinc salt in the zinc salt solution is 1:4-5:1.
  • a third method for preparing a quantum dot light emitting diode the quantum dot light emitting diode comprises an anode and a cathode arranged oppositely, a quantum dot light emitting layer arranged between the anode and the cathode, and a quantum dot light emitting layer arranged on the quantum dot light emitting layer and the electron transport layer between the cathode, wherein the electron transport layer comprises a first electron transport layer containing zinc oxide, and at least one surface of the first electron transport layer contains an amine with a carbon number of 8-18 base ligands and/or carboxyl ligands;
  • the carbon atoms of the amine ligand and/or the carboxyl ligand having 8-18 carbon atoms are 8-12, and the amine ligand having 8-18 carbon atoms and The addition amount of the carboxyl ligand satisfies: per 5 mg of zinc oxide prefabricated film, deposit 100 ⁇ L-500 ⁇ L of the amino ligand and/or carboxyl ligand solution with carbon atoms of 8-12.
  • the carbon atoms of the amine ligand and/or carboxyl ligand having 8-18 carbon atoms are 13-18, and the amine ligand having 8-18 carbon atoms and The addition amount of/or carboxyl ligand satisfies: per 5 mg of zinc oxide prefabricated film, deposit 50 ⁇ L-300 ⁇ L of amino ligand and/or carboxyl ligand solution with carbon atoms of 13-18.
  • the temperature of the drying treatment is 10°C to 100°C, and the drying time is 10 minutes to 2 hours.
  • the first electron transport layer is a metal-doped zinc oxide film.
  • the doped metal ions in the metal-doped zinc oxide thin film are selected from at least one of Mg 2+ and Mn 2+ ; or
  • the doped metal ions in the metal-doped zinc oxide film are selected from at least one of Al 3+ , Y 3+ , La 3+ , Li + , Gd 3+ , Zr 4+ , and Ce 4+ .
  • the doping concentration of the doping metal ions is as follows:
  • the doped metal ion is Mg 2+
  • the molar content of Mg 2+ in the metal-doped zinc oxide film accounts for 0.1% to 35% of the total molar amount of metal ions
  • the molar content of Al 3+ in the metal doped zinc oxide film accounts for 0.1% to 15% of the total molar amount of the metal ions;
  • the molar content of Y 3+ in the metal-doped zinc oxide film accounts for 0.1%-10% of the total molar amount of metal ions;
  • the doped metal ion is La 3+
  • the molar content of La 3+ in the metal-doped zinc oxide film accounts for 0.1%-7% of the total molar amount of metal ions
  • the molar content of Zr 4+ in the metal-doped zinc oxide film accounts for 0.1% to 45% of the total molar amount of metal ions;
  • the molar content of Ce 4+ in the metal doped zinc oxide film accounts for 0.1%-10% of the total molar amount of metal ions.
  • the preparation method of the zinc oxide prefabricated film is:
  • the zinc salt solution is mixed and reacted with the alkaline solution to prepare zinc oxide nanoparticles; the zinc oxide nanoparticles are dissolved to obtain a zinc oxide colloidal solution; a zinc oxide colloidal solution is formed on the prefabricated device substrate, and the solvent is removed to prepare a zinc oxide prefabricated solution film.
  • a fourth method for preparing a quantum dot light emitting diode the quantum dot light emitting diode comprises an anode and a cathode arranged oppositely, a quantum dot light emitting layer arranged between the anode and the cathode, and a quantum dot light emitting layer arranged on the quantum dot light emitting layer
  • An electron transport layer between the cathode and the cathode wherein the electron transport layer includes a first electron transport layer, and the first electron transport layer is a zinc oxide film with a surface hydroxyl group greater than or equal to 0.6;
  • the preparation method of the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 includes:
  • the zinc salt solution is mixed and reacted with the first alkaline solution to prepare zinc oxide; the zinc oxide is dissolved to obtain a zinc oxide colloidal solution; the second alkaline solution is added to the zinc oxide colloidal solution to adjust the zinc oxide colloidal solution.
  • the pH is greater than or equal to 8 to obtain a zinc oxide solution;
  • a zinc oxide solution is formed on the prefabricated device substrate on which the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 is to be prepared, and the solvent is removed to prepare the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6.
  • step of adding a second alkaline solution to the zinc oxide colloidal solution and adjusting the pH of the zinc oxide colloidal solution to be greater than or equal to 8 adding a second alkaline solution to the zinc oxide colloidal solution , so that the pH value of the obtained mixed solution is 9-12.
  • step of adding a second alkaline solution to the zinc oxide colloidal solution and adjusting the pH of the zinc oxide colloidal solution to be greater than or equal to 8 adding a second alkaline solution to the zinc oxide colloidal solution , so that the pH value of the obtained mixed solution is 9-10.
  • the alkali in the second alkali solution is selected from at least one of potassium hydroxide, sodium hydroxide, lithium hydroxide, TMAH, ammonia water, ethanolamine, and ethylenediamine.
  • the first alkali solution is selected from the first alkali solution formed by at least one of potassium hydroxide, sodium hydroxide, lithium hydroxide, TMAH, ammonia water, ethanolamine, and ethylenediamine.
  • the solvent in the zinc salt solution and the solvent in the first lye solution are each independently selected from at least one of water, organic alcohol, organic ether, and sulfone.
  • the solvent in the second alkali solution is selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and DMSO.
  • the dopant metal ion is selected from at least one of Mg 2+ , Mn 2+ ; or
  • the doped metal ions are selected from at least one of Al 3+ , Y 3+ , La 3+ , Li + , Gd 3+ , Zr 4+ , Ce 4+ .
  • the doping concentration of the doping metal ions is as follows:
  • the doped metal ion is Mg 2+
  • the molar content of Mg 2+ in the zinc salt solution accounts for 0.1% to 35% of the total molar amount of metal ions
  • the doped metal ion is Mn 2+
  • the molar content of Mn 2+ in the zinc salt solution accounts for 0.1% to 30% of the total molar amount of metal ions
  • the doped metal ion is Al 3+
  • the molar content of Al 3+ in the zinc salt solution accounts for 0.1%-15% of the total molar amount of metal ions
  • the doped metal ion is La 3+
  • the molar content of La 3+ in the zinc salt solution accounts for 0.1%-7% of the total molar amount of metal ions
  • the doped metal ion is Li +
  • the molar content of Li + in the zinc salt solution accounts for 0.1% to 45% of the total molar amount of metal ions
  • the molar content of Gd 3+ in the zinc salt solution accounts for 0.01% to 8% of the total molar amount of metal ions;
  • the molar content of Zr 4+ in the zinc salt solution accounts for 0.1% to 45% of the total molar amount of metal ions
  • the molar content of Ce 4+ in the zinc salt solution accounts for 0.1%-10% of the total molar amount of metal ions.
  • the addition amount of the zinc salt solution and the first lye solution satisfies: the product of the molar amount of the metal ion and the valence and the hydrogen
  • the molar ratio of oxygen ions is 0.75:1 to 1.25:1.
  • a fifth method for preparing a quantum dot light emitting diode the quantum dot light emitting diode comprises an anode and a cathode arranged oppositely, a quantum dot light emitting layer arranged between the anode and the cathode, and a quantum dot light emitting layer arranged on the quantum dot light emitting layer
  • An electron transport layer between the cathode and the cathode wherein the electron transport layer includes a first electron transport layer, and the first electron transport layer is a zinc oxide film with a surface hydroxyl group greater than or equal to 0.6;
  • the preparation method of the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 includes:
  • drying treatment is performed to obtain a zinc oxide film.
  • the concentration of the second alkali solution is 0.05-0.5 mmol/L.
  • the alkali in the second alkali solution is an inorganic alkali, and the concentration of the second alkali solution is 0.05-0.1 mmol/L.
  • the addition amount of the second lye solution satisfies: per 5 mg of the zinc oxide prefabricated film, 50 ⁇ L-400 ⁇ L of the first lye solution is used. Two lye for treatment.
  • the alkali in the second alkali solution is an organic alkali, and the concentration of the second alkali solution is 0.2-0.4 mmol/L.
  • the addition amount of the second lye solution satisfies: for every 5 mg of the zinc oxide prefabricated film, use 500 ⁇ L-1000 ⁇ L of the first lye solution. Two lye for treatment.
  • the temperature of the drying treatment is 10°C to 100°C, and the drying time is 10 minutes to 2 hours.
  • the zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 is a metal-doped zinc oxide film.
  • the doped metal ions in the metal-doped zinc oxide thin film are selected from at least one of Mg 2+ and Mn 2+ ; or
  • the doped metal ions in the metal-doped zinc oxide film are selected from at least one of Al 3+ , Y 3+ , La 3+ , Li + , Gd 3+ , Zr 4+ , and Ce 4+ .
  • the doping concentration of the doping metal ions is as follows:
  • the doped metal ion is Mg 2+
  • the molar content of Mg 2+ in the metal-doped zinc oxide film accounts for 0.1% to 35% of the total molar amount of metal ions
  • the doped metal ion is Mn 2+
  • the molar content of Mn 2+ in the metal-doped zinc oxide film accounts for 0.1%-30% of the total molar amount of metal ions
  • the molar content of Al 3+ in the metal doped zinc oxide film accounts for 0.1% to 15% of the total molar amount of the metal ions;
  • the doped metal ion is La 3+
  • the molar content of La 3+ in the metal-doped zinc oxide film accounts for 0.1%-7% of the total molar amount of metal ions
  • the doped metal ion is Li +
  • the molar content of Li + in the metal-doped zinc oxide film accounts for 0.1% to 45% of the total molar amount of the metal ions
  • the molar content of Gd 3+ in the metal doped zinc oxide film accounts for 0.01%-8% of the total molar amount of the metal ion;
  • the molar content of Zr 4+ in the metal-doped zinc oxide film accounts for 0.1% to 45% of the total molar amount of metal ions;
  • the molar content of Ce 4+ in the metal doped zinc oxide film accounts for 0.1%-10% of the total molar amount of metal ions.
  • the quantum dot light-emitting diode uses a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 as the first electron transport layer to suppress the transport of electrons in the electron transport layer and reduce the transport of electrons in the quantum dot light-emitting diode, thereby The electrons injected into the quantum dot light-emitting layer are reduced, the injection balance of carriers in the quantum dot light-emitting diode is realized, and finally a quantum dot light-emitting diode with higher external quantum efficiency is obtained; and the electron transport layer contains zinc oxide, and at least part of the When the surface of zinc oxide contains amine ligands and/or carboxyl ligands with 8-18 carbon atoms, due to the chain length of the coordinated amine ligands and/or carboxyl ligands with 8-18 carbon atoms Longer, under the effect of steric hindrance, the distance between zinc oxide nanoparticles in the film is increased, which in turn reduces the electron
  • FIG. 1 is a schematic structural diagram of an electron transport layer provided by an embodiment of the present application.
  • FIG. 2 is a schematic structural diagram of another electron transport layer provided in an embodiment of the present application.
  • FIG. 3 is a schematic structural diagram of a light emitting diode provided by an embodiment of the present application.
  • FIG. 4 is a schematic structural diagram of an upright light-emitting diode provided by an embodiment of the present application.
  • FIG. 5 is a schematic structural diagram of an inverted light-emitting diode provided by an embodiment of the present application.
  • FIG. 6 is a flow chart of the first preparation process of the zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 provided by the embodiment of the present application;
  • FIG. 7 is a flow chart of the second preparation process of the zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 provided by the embodiment of the present application;
  • FIG. 8 is a flow chart of a third preparation process of a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 provided by the embodiment of the present application;
  • Fig. 9 is the first preparation process flow of the first electron transport layer provided by the embodiment of the present application, using zinc oxide containing amine ligands and/or carboxyl ligands with 8-18 carbon atoms on the surface as the electron transport material picture;
  • Fig. 11 is the schematic diagram that utilizes X-ray photoelectron spectroscopy (XPS) to test hydroxyl oxygen peak area and lattice oxygen peak area provided in the embodiment of this application, and calculates the ratio of the two to obtain the schematic diagram of hydroxyl content;
  • XPS X-ray photoelectron spectroscopy
  • FIG. 13 is a schematic diagram of characterizing the life of a device provided by an embodiment of the present application.
  • Fig. 14 is the device EQE test result diagram of the quantum dot light-emitting diode provided in Example 1 and Comparative Example 1 of the present application;
  • Example 16 is a graph showing the results of the life test of the quantum dot light-emitting diodes provided in Example 2 and Comparative Example 1 of the present application;
  • Fig. 17 is the device EQE test result diagram of the quantum dot light-emitting diode provided in Example 3 of the present application and Comparative Example 1;
  • Example 18 is a graph showing the results of the life test of the quantum dot light-emitting diodes provided in Example 3 and Comparative Example 1 of the present application;
  • Fig. 19 is the EQE test result diagram of the quantum dot light-emitting diodes provided in Example 4 and Comparative Example 2 of the present application;
  • Fig. 20 is the EQE test result diagram of the quantum dot light-emitting diodes provided in Example 5 of the present application and Comparative Example 2;
  • Fig. 21 is the EQE test result diagram of the quantum dot light-emitting diodes provided in Example 6 of the present application and Comparative Example 2;
  • Example 22 is a graph showing the EQE test results of the quantum dot light-emitting diodes provided in Example 7 and Comparative Example 2 of the present application.
  • the electron mobility of the zinc oxide layer is often higher than the hole mobility of the hole transport layer.
  • the electron mobility of the zinc oxide layer is reduced by inserting an electron blocking layer between the quantum dot light-emitting layer and the zinc oxide layer, so that the quantum dots The electrons and holes injected into the light-emitting layer reach equilibrium.
  • there are certain limitations in improving the carrier injection balance by using methods such as inserting electron blocking layers to change the device structure.
  • this method is difficult to achieve in actual device fabrication, because the electron blocking layer has strict thickness requirements, and it is difficult to play an effective role if it is too thick or too thin, and even reduces the device performance of quantum dot light-emitting diodes. Therefore, it is difficult to control in actual operation.
  • the method of changing the device structure increasing the electron blocking layer will also increase the fabrication cost of the device, which will increase the cost burden in the mass production of quantum dot light-emitting diode devices in the future.
  • the present application realizes the regulation of the electron injection rate by regulating the amount of hydroxyl groups on the surface of the zinc oxide thin film, reduces the electrons injected into the quantum dot light-emitting layer, and realizes the injection balance of carriers in the quantum dot light-emitting diode, Finally, a quantum dot light-emitting diode device with high external quantum efficiency is obtained.
  • the quantum dot light-emitting diode provided by the present application uses a zinc oxide film with a large amount of hydroxyl groups on the surface as the electron transport layer. In this case, since the injection rate of electrons into the quantum dot light-emitting layer is reduced, the injection of holes and electrons is more balanced, so that the external quantum efficiency of the device is improved.
  • the quantum dot light-emitting diode provided by the embodiment of the present application includes an anode and a cathode disposed oppositely, a quantum dot light-emitting layer disposed between the anode and the cathode, and a quantum dot light-emitting layer disposed between the quantum dot light-emitting layer and the cathode the electron transport layer;
  • the zinc oxide in the first electron transport layer is metal-doped or undoped zinc oxide.
  • the energy level/oxygen vacancy (electron mobility) of the doped zinc oxide electron transport layer changes, and the dopant ions will preferentially fill the surface defects after entering the surface of the zinc oxide particles, which will passivate to a certain extent.
  • the newly filled dopant ion sites will coordinate new surface hydroxyl groups, so the total surface hydroxyl group will increase.
  • the amount of surface hydroxyl groups of the zinc oxide film containing the doped metal is greater than or equal to 0.8; in some embodiments, the amount of surface hydroxyl groups of the zinc oxide film containing the doped metal is greater than or equal to 1.0.
  • the doping amount of the doping metal ion is regulated according to the difference between the ionic radius of the selected doping metal ion and the Zn 2+ ion, and the ionic radius of the doping metal ion is closer to the ionic radius of the zinc ion, and the two are oxidized.
  • the doping metal when the doping metal is Mg 2+ , the doping molar concentration of Mg 2+ in the zinc oxide film containing the doping metal is 0.1%-35%; when the doping metal is Mn 2+ , the doping The doping molar concentration of Mn 2+ in the zinc oxide film containing the doped metal is 0.1%-30%; when the doping metal is Al 3+ , the doping molar concentration of Al 3+ in the zinc oxide film containing the doping metal is 0.1% ⁇ 15%; when the doping metal is Y 3+ , the doping molar concentration of Y 3+ in the zinc oxide film containing the doping metal is 0.1% ⁇ 10%; when the doping metal is La 3+ , The doping molar concentration of La 3+ in the zinc oxide film containing the doping metal is 0.1% to 7%; when the doping metal is Li + , the doping molar concentration of Li + in the zinc oxide film containing the doping metal is 0.1% ⁇ 45%; when the doping metal is
  • the thickness of the first electron transport layer is 10-100 nm.
  • the electron transport layer further includes a second electron transport layer, and the second electron transport layer is a zinc oxide film with a surface hydroxyl amount of less than or equal to 0.4. That is, the electron transport layer includes both a zinc oxide film with a surface hydroxyl amount less than or equal to 0.4 and a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6, which are stacked along the direction perpendicular to the quantum dot light-emitting layer or the cathode.
  • both the zinc oxide in the first electron transport layer and the second electron transport layer are undoped zinc oxide. That is, the first electron transport layer and the second electron transport layer are made of zinc oxide, and zinc oxide does not contain dopant metal.
  • the electron transport layer is composed of a zinc oxide film with surface hydroxyl groups greater than or equal to 0.6, namely the first electron transport layer, and a zinc oxide film with surface hydroxyl groups less than or equal to 0.4, namely the second electron transport layer.
  • the zinc oxide in at least one of the first electron transport layer and the second electron transport layer is metal-doped zinc oxide.
  • the high hydroxyl content can reduce the electrons injected into the quantum dot light-emitting layer, realize the injection balance of carriers in the quantum dot light-emitting diode device, and finally obtain a quantum dot light-emitting diode device with high external quantum efficiency.
  • metal ions are doped into zinc oxide with surface hydroxyl content less than or equal to 0.4 to achieve effective carrier injection regulation.
  • a quantum dot light-emitting diode with an electron transport layer compared to undoped zinc oxide film can be obtained.
  • the higher EQE of the device and the surface hydroxyl content of the first electron transport layer is greater than or equal to 0.6, the two synergistically can improve the EQE of the quantum dot light-emitting diode device more effectively.
  • the high hydroxyl content can reduce the electrons injected into the quantum dot light-emitting layer, realize the injection balance of carriers in the quantum dot light-emitting diode device, and finally obtain a quantum dot light-emitting diode device with high external quantum efficiency.
  • metal ions are doped in zinc oxide with surface hydroxyl content greater than or equal to 0.6 and zinc oxide with surface hydroxyl content less than or equal to 0.4 to achieve effective carrier injection regulation.
  • the higher EQE of the quantum dot light-emitting diode device with the zinc oxide film as the electron transport layer, and the surface hydroxyl content of the first electron transport layer is greater than or equal to 0.6, the three synergistically can significantly improve the EQE of the quantum dot light-emitting diode device.
  • the electron transport layer is composed of a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 (the first electron transport layer) and a zinc oxide film with a surface hydroxyl amount less than or equal to 0.4 (the second electron transport layer), and the first electron transport layer
  • the zinc oxides in the electron transport layer and the second electron transport layer are all metal-doped zinc oxides.
  • the electron transport layer includes a first electron transport layer and a second electron transport layer, the second electron transport layer is disposed on a surface of the first electron transport layer close to the cathode or the quantum dot light-emitting layer, and the second electron transport layer
  • the transport layer is a metal-doped zinc oxide film.
  • the external quantum efficiency (EQE) of quantum dot light-emitting diodes can be optimized by optimizing the energy level matching or electron mobility of doped zinc oxide, while increasing the amount of hydroxyl groups on the surface of zinc oxide.
  • the electron transport layer 50 includes a first electron transport layer 51 and a second electron transport layer 52
  • the second electron transport layer 52 is a metal-doped zinc oxide film
  • the second electron transport layer 52 It is disposed on the surface of the first electron transport layer 51 close to the quantum dot light-emitting layer 40 , that is, the first electron transport layer 51 is close to the cathode 60 .
  • the metal-doped zinc oxide colloidal solution is deposited on the quantum dot light-emitting layer, it is beneficial to obtain a more flat zinc oxide film.
  • the electron transport layer is a double-layer zinc oxide film, the thickness of each zinc oxide film is 10-100 nm.
  • the thickness of the zinc oxide film is suitable, and it is not easy to be broken down by electrons, which is beneficial to maintain the injection performance, film formation quality and surface flatness of the electron transport layer.
  • the film thickness should not be too thick due to its low electron mobility.
  • the thickness of the zinc oxide film or the metal-doped zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 is 10-30 nm.
  • the film thickness can be appropriately thicker.
  • the thickness of the zinc oxide film or the metal-doped zinc oxide film with the surface hydroxyl amount less than or equal to 0.4 is 20-60 nm.
  • the electron transport layer includes n thin film stack units consisting of a first electron transport layer and a second electron transport layer, wherein n is greater than or equal to 2.
  • the electron transport layer adopts a stacking method, which may make the energy level matching better and improve the device life more greatly.
  • n is an integer greater than or equal to 2 and less than or equal to 9.
  • the electron transport layer further includes a third electron transport layer. That is, the electron transport layer includes a zinc oxide film with surface hydroxyl groups greater than or equal to 0.6, namely a first electron transport layer, a second electron transport layer, and a third electron transport layer.
  • the second electron transport layer is a zinc oxide film with a surface hydroxyl amount less than or equal to 0.4, a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6, or a metal-doped zinc oxide film.
  • the third electron transport layer is a zinc oxide film with surface hydroxyl groups greater than or equal to 0.6.
  • the electron transport layer comprises a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 (ie, the first electron transport layer), a zinc oxide film with a surface hydroxyl amount less than or equal to 0.4 (ie the second electron transport layer), and a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 (ie, the third electron transport layer), wherein the third electron transport layer is arranged on the side of the second electron transport layer away from the first electron transport layer surface.
  • a layer of zinc oxide film with low hydroxyl content enables the quantum dot light-emitting diode device to reach a carrier injection equilibrium state when it continues to work to a stable state, thereby obtaining a good device lifetime; while two layers of high hydroxyl group A large amount of zinc oxide film can reduce the electrons injected into the quantum dot light-emitting layer, realize the injection balance of carriers in the quantum dot light-emitting diode device, and finally obtain a quantum dot light-emitting diode device with high external quantum efficiency.
  • the third electron transport layer is a zinc oxide thin film with surface hydroxyl groups less than or equal to 0.4.
  • the double-layer zinc oxide film with low hydroxyl content enables the quantum dot light-emitting diode device to reach a carrier injection equilibrium state when it continues to work to a stable state, thereby obtaining a good device lifetime; while the high hydroxyl content
  • the zinc oxide film can reduce the electrons injected into the quantum dot light-emitting layer, realize the injection balance of carriers in the quantum dot light-emitting diode device, and finally obtain a quantum dot light-emitting diode device with high external quantum efficiency.
  • zinc oxide or doped zinc oxide colloidal solution with less surface hydroxyl groups is deposited on the quantum dot light-emitting layer, it is beneficial to obtain a more flat zinc oxide film.
  • the obtained quantum dot light emitting diode device has both good EQE and device lifetime.
  • the electron transport layer includes a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 (ie, the first electron transport layer), a metal-doped zinc oxide film (the second electron transport layer), and a surface hydroxyl amount of less than or equal to 0.6.
  • the low hydroxyl content enables the quantum dot light-emitting diode device to reach a carrier injection equilibrium state when it continues to work to a stable state, thereby obtaining a good device lifetime.
  • the high hydroxyl content can reduce the electrons injected into the quantum dot light-emitting layer, realize the injection balance of carriers in the quantum dot light-emitting diode device, and finally obtain a quantum dot light-emitting diode device with high external quantum efficiency.
  • the zinc oxide of the second electron transport layer is doped with metal ions to achieve effective carrier injection regulation. In the early stage of the device operation, the quantum dot light-emitting diode device with the undoped zinc oxide film as the electron transport layer can be obtained. The EQE of quantum dot light-emitting diode devices can be more significantly improved.
  • the third electron transport layer is a metal-doped zinc oxide film.
  • the electron transport layer comprises a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 (ie, the first electron transport layer), a zinc oxide film with a surface hydroxyl amount less than or equal to 0.4 (ie the second electron transport layer), and a metal-doped zinc oxide thin film (third electron transport layer), and the third electron transport layer is disposed on the side surface of the second electron transport layer away from the first electron transport layer.
  • the electron mobility is further enhanced by the zinc oxide film with low hydroxyl content, so that the quantum dot light-emitting diode device can also reach the carrier injection equilibrium state when it continues to work to a stable state, and thus obtain good
  • the zinc oxide film with high hydroxyl content can reduce the electrons injected into the quantum dot light-emitting layer, realize the injection balance of carriers at the initial stage of operation of the quantum dot light-emitting diode device, and finally obtain the quantum dot luminescence with high external quantum efficiency. diode device.
  • the quantum dot light-emitting diode device is already in a better carrier injection balance.
  • the quantum dot light-emitting diode device with the transport layer has higher external quantum efficiency (EQE); and due to the low amount of hydroxyl groups on the surface of the doped zinc oxide film, the quantum dot light-emitting diode device can also reach the load when it continues to work to a stable state. Jets are injected into the equilibrium state. As a result, the quantum dot light-emitting diode can obtain better device life and maintain a higher EQE in the early working stage.
  • the third electron transport layer is disposed adjacent to the quantum dot light emitting layer. Since the doped zinc oxide colloidal solution is deposited on the quantum dot light-emitting layer, it is beneficial to obtain a more flat zinc oxide film.
  • the zinc oxide in the zinc oxide film with the surface hydroxyl amount less than or equal to 0.4 may be undoped zinc oxide or metal-doped zinc oxide ;
  • the zinc oxide in the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 may be undoped zinc oxide or metal-doped zinc oxide.
  • the electron transport layer has a thickness of 10-100 nm. In some embodiments, the thickness of the zinc oxide film with the surface hydroxyl amount less than or equal to 0.4 is 20-60 nm. In some embodiments, the thickness of the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 is 10-30 nm. In some embodiments, the thickness of the metal-doped zinc oxide film is 10-30 nm. The thickness of each layer is within this range, so that in this case, the thickness of the zinc oxide film is suitable, and it is not easy to be broken down by electrons, which is conducive to maintaining the injection performance, film formation quality and surface flatness of the electron transport layer.
  • zinc oxide films or metal-doped zinc oxide films with surface hydroxyl content greater than or equal to 0.6 have relatively thin film thicknesses due to their low electron mobility; zinc oxide films with surface hydroxyl content less than or equal to 0.4, due to Its electron mobility is high, so the film thickness is relatively thick.
  • the electron transport layer includes a second electron transport layer, and the second electron transport layer is an embodiment of a metal-doped zinc oxide film, and the electron transport layer includes a second electron transport layer and a third electron transport layer, and the second electron transport layer and/or in the embodiment in which the third electron transport layer is a metal-doped zinc oxide film, in some embodiments, the type of doping metal in the metal-doped zinc oxide film, the effect of the doping metal, and the doping
  • the doping content of the metal is as described above (in the case where the electron transport layer is the first electron transport layer).
  • the doping metal in the metal-doped zinc oxide thin film is selected from at least one of Mg 2+ and Mn 2+ . In some embodiments, the doping metal in the metal-doped zinc oxide film is selected from at least one of Al 3+ , Y 3+ , La 3+ , Li + , Gd 3+ , Zr 4+ , Ce 4+ .
  • the doping molar concentration of Mg 2+ in the metal-doped zinc oxide film is 0.1%-35%; when the doping metal is Mn 2+ , the doping molar concentration of Mg 2+ The doping molar concentration of Mn 2+ in the doped zinc oxide film is 0.1%-30%; when the doping metal is Al 3+ , the doping molar concentration of Al 3+ in the metal-doped zinc oxide film is 0.1%-15% %; when the doping metal is Y 3+ , the doping molar concentration of Y 3+ in the metal-doped zinc oxide film is 0.1%-10%; when the doping metal is La 3+ , the metal-doped zinc oxide film The doping molar concentration of La 3+ is 0.1%-7%; when the doping metal is Li + , the doping molar concentration of Li + in the metal-doped zinc oxide film is 0.1%-45%; when the doping metal is Li +
  • the quantum dot light-emitting diodes provided in the embodiments of the present application use a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 as the first electron transport layer to suppress the transport of electrons in the electron transport layer and reduce the transport of electrons in the quantum dot light-emitting diodes , thereby reducing the electrons injected into the quantum dot light emitting layer, realizing the injection balance of carriers in the quantum dot light emitting diode, and finally obtaining a quantum dot light emitting diode with higher external quantum efficiency.
  • the quantum dot light-emitting diode provided by the present application can realize the carrier injection balance of the quantum dot light-emitting diode device only by regulating the amount of hydroxyl groups on the surface of the zinc oxide film, without changing the device structure (inserting the electron blocking layer), and without doping
  • the zinc oxide film is modified by means such as the method, and the whole process is simple to operate, low cost, and has good repeatability.
  • an embodiment of the present application provides a quantum dot light-emitting diode, comprising an anode and a cathode disposed oppositely, a quantum dot light-emitting layer disposed between the anode and the cathode, and an electron transport disposed between the quantum dot light-emitting layer and the cathode Floor;
  • the electron transport layer contains zinc oxide, and at least part of the surface of the zinc oxide contains amine ligands and/or carboxyl ligands having 8-18 carbon atoms.
  • the electron transport layer due to the longer chain length of the amine ligands and/or carboxyl ligands with carbon atoms of 8-18 coordinated with zinc oxide, under the effect of steric hindrance, the oxidation of the film increases.
  • the distance between the zinc nanoparticles reduces the electron mobility of the electron transport layer, inhibits the transport of electrons in the electron transport layer, and reduces the transport of electrons in the quantum dot light-emitting diode, thereby reducing the electrons injected into the quantum dot light-emitting layer. , realize the injection balance of carriers in the quantum dot light-emitting diode, and finally obtain a quantum dot light-emitting diode with higher external quantum efficiency.
  • the chain length of the amine ligand and/or the carboxyl ligand that is, the number of carbon atoms, needs to be strictly controlled.
  • the chain length is too short, it is not easy to increase the distance between the ZnO nanoparticles, and then it is not easy to reduce the electron mobility of the electron transport layer; when the chain length is too long, due to the weak polarity of the ligand, It is not easy to effectively disperse in the highly polar zinc oxide colloidal solution, and is bound to the surface of zinc oxide nanoparticles through ligand exchange.
  • the amine ligand and/or carboxyl ligand having 8-18 carbon atoms is selected from at least one of caprylic acid, octylamine, dodecanoic acid, dodecylamine, oleic acid, and oleylamine.
  • the number of carbon atoms of the amine ligand and/or the carboxyl ligand is 8-12, so that the electron mobility of the electron transport layer is reduced, and the film quality is better.
  • the electron transport layer includes a first electron transport layer containing zinc oxide, and the surface of the zinc oxide forming the first electron transport layer contains amine ligands and/or carboxyl ligands with 8-18 carbon atoms .
  • the introduction of amine ligands and/or carboxyl ligands can increase the distance between the zinc oxide nanoparticles after film formation, thereby reducing the electron mobility of the first electron transport layer after film formation.
  • the amino ligands and/or carboxyl ligands with a carbon number of 8-18 The molar ratio to zinc oxide is 1:4 to 10:1.
  • the appropriate amount of amine ligands and/or carboxyl ligands on the surface of zinc oxide nanoparticles can reduce the electron mobility of the electron transport layer containing zinc oxide, and make the electrons and voids in the light-emitting layer of the quantum dots.
  • the holes tend to be balanced, thereby improving the external quantum efficiency of the quantum dot light-emitting diode.
  • the electron mobility of the sample will decrease after the ligand exchange. Therefore, the electron mobility can be reduced and the EQE can be improved even if the ligand with a longer chain length is not added in a small amount.
  • the solubility of zinc oxide nanoparticles in polar solvents will be reduced, the film formation of the zinc oxide layer in the final device will be affected, and the device performance of the final device will be reduced;
  • the ligand chain length is short (8-12), the decrease of the electron mobility after ligand exchange is small, so the addition amount of the ligand with more chain length needs to be higher to achieve the purpose of improving EQE.
  • the number of carbon atoms of the amine ligand and/or carboxyl ligand is 8-12, and the molar ratio of the amine ligand and/or carboxyl ligand to the zinc oxide nanoparticles is selected to be 1:1-10 : 1; In some embodiments, the number of carbon atoms of the amine ligand and/or the carboxyl ligand is 13-18, and the molar ratio of the amine ligand and/or the carboxyl ligand to the zinc oxide nanoparticle is selected as 1: 4 to 5:1.
  • the electron transport layer includes only one thin film, and the thin film is the first electron transport layer, that is, the material forming the electron transport layer is zinc oxide, and the surface of the zinc oxide contains 8- 18 Amine ligands and/or carboxyl ligands.
  • the transport resistance of electrons in the electron transport layer to the light-emitting layer of the quantum dot is large, and the injection rate of electrons to the light-emitting layer of the quantum dot decreases, and the lower electron injection rate and hole injection rate are favorable for carriers
  • the injection balance improves the external quantum efficiency of the quantum dot light-emitting diode device.
  • the zinc oxide in the first electron transport layer is undoped zinc oxide, that is, the electron transport layer is composed of zinc oxide containing amine ligands and/or carboxyl ligands with 8-18 carbon atoms on the surface.
  • zinc oxide does not contain dopant metals.
  • the undoped zinc oxide film referred to in the embodiments of the present application is a zinc oxide film that is relatively metal-doped zinc oxide film, which means that the zinc oxide forming the zinc oxide film is not doped with other metal ions. . That is, the undoped zinc oxide film is a pure zinc oxide film.
  • the zinc oxide in the first electron transport layer is metal-doped zinc oxide, that is, the zinc oxide in the electron transport layer is zinc oxide containing a doped metal.
  • the doped metal referred to in this application refers to other metal ions different from zinc ions that are doped into zinc oxide in the form of ions.
  • the quantum dot light-emitting diode device can be optimized by energy level matching optimization or electron mobility optimization of the doped zinc oxide film. Under the better carrier injection balance, the device can obtain higher external quantum efficiency (EQE) than the quantum dot light-emitting diode device with the undoped zinc oxide film as the electron transport layer in the early stage of operation.
  • EQE external quantum efficiency
  • the type of doping metal in the metal-doped zinc oxide film, the effect of the doping metal, and the doping content of the doping metal are as described above (the case where the electron transport layer is the first electron transport layer), in order to save space , and will not be repeated here.
  • the doping metal in the metal-doped zinc oxide thin film is selected from at least one of Mg 2+ and Mn 2+ . In some embodiments, the doping metal in the metal-doped zinc oxide film is selected from at least one of Al 3+ , Y 3+ , La 3+ , Li + , Gd 3+ , Zr 4+ , Ce 4+ .
  • the doping amount of the doping metal ions is referred to above, and is not repeated here.
  • the thickness of the first electron transport layer is 10-100 nm.
  • the electron transport layer further includes a second electron transport layer, and the second electron transport layer is a zinc oxide film with a surface hydroxyl amount of less than or equal to 0.4. That is, the electron transport layer also includes a zinc oxide film with amine ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface and a zinc oxide film with a surface hydroxyl amount of less than or equal to 0.4.
  • the point light-emitting layer or the cathode is stacked in the direction, that is, the second electron transport layer is disposed on the surface of the first electron transport layer on the side close to the cathode or the quantum dot light-emitting layer.
  • the use of double-layer zinc oxide electron transport in which the zinc oxide film containing amine ligands and/or carboxyl ligands with carbon atoms of 8-18 on the surface, can reduce the electron transport layer to quantum dots
  • the electrons injected into the light-emitting layer make the electron injection efficiency of the quantum dot light-emitting diode device low in the early stage of operation, and realize the injection balance of carriers in the quantum dot light-emitting diode device.
  • the first electron transport layer and the second electron transport layer are stacked and arranged, and the relative positions of the two can be set flexibly.
  • the second electron transport layer is disposed on a side surface of the first electron transport layer close to the quantum dot light-emitting layer. In this case, when the zinc oxide solution with less surface hydroxyl groups is deposited on the quantum dot light-emitting layer, it is beneficial to obtain a more flat zinc oxide film.
  • the second electron transport layer may also be disposed on the surface of the first electron transport layer on one side close to the quantum dot light-emitting layer.
  • both the first electron transport layer and the second electron transport layer are undoped zinc oxide films. That is, the first electron transport layer and the second electron transport layer are made of zinc oxide, zinc oxide does not contain dopant metal, but the zinc oxide surface of the first electron transport layer contains amine ligands with carbon atoms of 8-18 and/or carboxyl ligands.
  • the electron transport layer is composed of a first electron transport layer containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface and a second electron transport layer with a surface hydroxyl amount of less than or equal to 0.4 composition.
  • the electron transport layer further includes a second electron transport layer, and the second electron transport layer is a zinc oxide film with a surface hydroxyl amount of less than or equal to 0.4, and both the first electron transport layer and the second electron transport layer are undoped Zinc oxide thin film, and the second electron transport layer is arranged on the surface of one side adjacent to the quantum dot light-emitting layer.
  • the zinc oxide in at least one of the first electron transport layer and the second electron transport layer is metal-doped zinc oxide.
  • the zinc oxide film whose surface contains amine ligands and/or carboxyl ligands with a carbon number of 8-18, that is, the zinc oxide in the first electron transport layer is metal-doped zinc oxide, and the surface hydroxyl group is The zinc oxide film less than or equal to 0.4, that is, the second electron transport layer is an undoped zinc oxide film.
  • the zinc oxide film containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface, that is, the first electron transport layer can reduce the injection into the quantum dot light-emitting layer.
  • the electrons in the quantum dot light-emitting diode device realize the injection balance of carriers in the quantum dot light-emitting diode device, and finally a quantum dot light-emitting diode device with high external quantum efficiency is obtained.
  • the zinc oxide film with low surface hydroxyl content that is, the second electron transport layer, enables the quantum dot light-emitting diode device to reach a carrier injection equilibrium state when it continues to work to a stable state, thereby obtaining a good device life.
  • metal ions are doped into zinc oxide with amine ligands and/or carboxyl ligands of 8-18 carbon atoms to achieve effective carrier injection regulation.
  • the higher EQE of the quantum dot light-emitting diode device with the zinc film as the electron transport layer, coupled with the role of the amine ligands and/or carboxyl ligands with carbon atoms of 8-18 in the first electron transport layer, the two synergistically, can More effectively improve the EQE of quantum dot light-emitting diode devices.
  • the carrier injection balance of the QLED device can be achieved by regulating the amount of hydroxyl groups on the surface of the zinc oxide film, without changing the device structure (inserting an electron blocking layer), and without modifying the zinc oxide film by doping and other means.
  • the process is simple to operate, low cost, and has good repeatability.
  • the electron transport layer is composed of a zinc oxide film (the first electron transport layer) containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface and undoped surfaces with a surface hydroxyl amount of less than or equal to 0.4. It is composed of a doped zinc oxide thin film (second electron transport layer), and the zinc oxide in the first electron transport layer is metal-doped zinc oxide.
  • the electron transport layer is made of a metal-doped zinc oxide thin film (the first electron transport layer) with surface containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 and the surface hydroxyl group is less than or It consists of an undoped zinc oxide thin film (second electron transport layer) equal to 0.4, and the second electron transport layer is disposed on the surface of one side adjacent to the quantum dot light-emitting layer.
  • the first electron transport layer with surface containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 and the surface hydroxyl group is less than or It consists of an undoped zinc oxide thin film (second electron transport layer) equal to 0.4, and the second electron transport layer is disposed on the surface of one side adjacent to the quantum dot light-emitting layer.
  • the first electron transport layer containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface is an undoped zinc oxide thin film, and the surface hydroxyl amount is less than or equal to 0.4 zinc oxide
  • the zinc oxide in the thin film, ie, the second electron transport layer, is metal-doped zinc oxide.
  • the first electron transport layer containing amine ligands and/or carboxyl ligands with 8-18 carbon atoms on the surface can reduce the electrons injected into the light-emitting layer of quantum dots and realize light-emitting of quantum dots
  • the injection of carriers in the diode device is balanced, and finally a quantum dot light-emitting diode device with higher external quantum efficiency is obtained.
  • the second electron transport layer with low surface hydroxyl content enables the quantum dot light-emitting diode device to reach a carrier injection equilibrium state when it continues to work to a stable state, thereby obtaining a good device lifetime.
  • the zinc oxide in the second electron transport layer is doped with metal ions to achieve effective carrier injection regulation.
  • more quantum dot light-emitting diode devices can be obtained than the quantum dot light-emitting diode devices with the undoped zinc oxide film as the electron transport layer.
  • the high EQE combined with the role of the amine ligands and/or carboxyl ligands with 8-18 carbon atoms in the first electron transport layer, synergistically improve the EQE of the quantum dot light-emitting diode device.
  • the carrier injection balance of the QLED device can be achieved by regulating the amount of hydroxyl groups on the surface of the zinc oxide film, without changing the device structure (inserting an electron blocking layer), and without modifying the zinc oxide film by doping and other means.
  • the process is simple to operate, low cost, and has good repeatability.
  • the electron transport layer is composed of an undoped zinc oxide film (the first electron transport layer) of amine ligands and/or carboxyl ligands with a carbon number of 8-18 and an oxide with a surface hydroxyl amount of less than or equal to 0.4.
  • a zinc thin film (second electron transport layer) is formed, and the zinc oxide in the second electron transport layer is metal-doped zinc oxide.
  • the electron transport layer is composed of an undoped zinc oxide film (the first electron transport layer) of amine ligands and/or carboxyl ligands with 8-18 carbon atoms and the surface hydroxyl amount is less than or equal to 0.4
  • the zinc oxide film (the second electron transport layer) is composed of the zinc oxide film (the second electron transport layer), and the zinc oxide in the second electron transport layer is metal-doped zinc oxide, and the second electron transport layer is arranged on the surface of one side adjacent to the light-emitting layer of the quantum dots.
  • the first electron transport layer containing amine ligands and/or carboxyl ligands with 8-18 carbon atoms on the surface can reduce the electrons injected into the light-emitting layer of quantum dots and realize light-emitting of quantum dots
  • the injection of carriers in the diode device is balanced, and finally a quantum dot light-emitting diode device with higher external quantum efficiency is obtained.
  • the second electron transport layer with low surface hydroxyl content enables the quantum dot light-emitting diode device to reach a carrier injection equilibrium state when it continues to work to a stable state, thereby obtaining a good device lifetime.
  • metal ions are doped in the zinc oxide of the first electron transport layer and the second electron transport layer to achieve effective carrier injection regulation.
  • metal ions are doped in the zinc oxide of the first electron transport layer and the second electron transport layer to achieve effective carrier injection regulation.
  • the higher EQE of quantum dot light-emitting diode devices combined with the synergistic effect of amine ligands and/or carboxyl ligands with 8-18 carbon atoms in the first electron transport layer, can significantly improve the EQE of quantum dot light-emitting diode devices.
  • the carrier injection balance of the QLED device can be achieved by regulating the amount of hydroxyl groups on the surface of the zinc oxide film, without changing the device structure (inserting an electron blocking layer), and without modifying the zinc oxide film by doping and other means.
  • the process is simple to operate, low cost, and has good repeatability.
  • the electron transport layer is composed of a zinc oxide thin film (the first electron transport layer) containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface and zinc oxide with a surface hydroxyl amount greater than or equal to 0.6.
  • a thin film (a second electron transport layer) is formed, and the zinc oxide in the first electron transport layer and the second electron transport layer are both metal-doped zinc oxide.
  • the electron transport layer is made of a metal-doped zinc oxide thin film (the first electron transport layer) with surface containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 and a surface hydroxyl group greater than or It consists of a metal-doped zinc oxide thin film (second electron transport layer) equal to 0.6, and the second electron transport layer is arranged on the surface of one side adjacent to the quantum dot light-emitting layer.
  • the first electron transport layer with surface containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 and a surface hydroxyl group greater than or It consists of a metal-doped zinc oxide thin film (second electron transport layer) equal to 0.6, and the second electron transport layer is arranged on the surface of one side adjacent to the quantum dot light-emitting layer.
  • the electron transport layer 50 is composed of a first electron transport layer 51 and a second electron transport layer 52 , and the second electron transport layer 52 is larger than the first electron transport layer 51 . It is closer to the quantum dot light-emitting layer 40 , that is, the first electron transport layer 51 is closer to the cathode 60 .
  • the zinc oxide colloidal solution with a low amount of hydroxyl groups on the surface is deposited on the quantum dot light-emitting layer, it is beneficial to obtain a more flat zinc oxide film.
  • the electron transport layer includes a second electron transport layer, the second electron transport layer is disposed on a surface of the first electron transport layer close to the cathode or the quantum dot light-emitting layer, and the second electron transport layer is metal doped Zinc oxide film.
  • the first electron transport layer containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface can reduce the electrons injected into the quantum dot light-emitting layer and realize the quantum dot light-emitting diode device.
  • the injection of carriers is balanced, and finally a quantum dot light-emitting diode device with higher external quantum efficiency is obtained.
  • the energy level matching optimization or electron mobility optimization of metal-doped zinc oxide further optimizes the external quantum efficiency (EQE) of quantum dot light-emitting diodes.
  • the thickness of each zinc oxide film is 10-100 nm.
  • the thickness of the zinc oxide film is suitable, and it is not easy to be broken down by electrons, which is beneficial to maintain the injection performance, film formation quality and surface flatness of the electron transport layer.
  • the film thickness should not be too thick due to its low electron mobility.
  • the thickness of the metal-doped zinc oxide film is 10-30 nm.
  • the thickness of the zinc oxide thin film containing amine ligands and/or carboxyl ligands with 8 to 18 carbon atoms on the surface is 10 to 80 nm.
  • the film thickness can be appropriately thicker.
  • the thickness with which the surface hydroxyl amount is less than or equal to 0.4 is 20-60 nm.
  • the electron transport layer includes n thin film stack units consisting of a first electron transport layer and a second electron transport layer, wherein n is greater than or equal to 2.
  • the electron transport layer adopts a stacking method, which may make the energy level matching better and improve the device life more greatly.
  • n is an integer greater than or equal to 2 and less than or equal to 9.
  • the electron transport layer includes a second electron transport layer and a third electron transport layer.
  • the second electron transport layer is a zinc oxide film with surface hydroxyl groups less than or equal to 0.4
  • the third electron transport layer is selected from zinc oxide films with surface hydroxyl groups greater than or equal to 0.6
  • the second electron transport layer combines On the side surface of the first electron transport layer, the third electron transport layer is bonded to the side surface of the second electron transport layer away from the first electron transport layer.
  • a layer of zinc oxide film containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface and a layer of zinc oxide film with high hydroxyl content on the surface can reduce the emission layer of quantum dots
  • the electrons injected into the quantum dot light-emitting diode device realize the injection balance of the carriers in the quantum dot light-emitting diode device, and finally make the quantum dot light-emitting diode have a high external quantum efficiency in the early stage of operation; and a layer of zinc oxide film with low hydroxyl content makes the quantum dot light-emitting diodes have high external quantum efficiency.
  • the light-emitting diode device can also reach a carrier injection equilibrium state when it continues to work to a stable state, thereby obtaining a good device life.
  • the second electron transport layer is a zinc oxide film with surface hydroxyl groups less than or equal to 0.4
  • the third electron transport layer is selected from amine ligands and/or carboxyl ligands containing 8-18 carbon atoms on the surface.
  • the zinc oxide thin film of the body is formed, the second electron transport layer is bonded to the surface of the first electron transport layer, and the third electron transport layer is bonded to the side surface of the second electron transport layer away from the first electron transport layer.
  • the two-layer zinc oxide film containing amine ligands and/or carboxyl ligands with carbon atoms of 8-18 on the surface can reduce the electrons injected into the quantum dot light-emitting layer and realize the quantum dot light-emitting diode device
  • the injection balance of medium carriers finally makes the quantum dot light-emitting diode have high external quantum efficiency in the early stage of operation; and a layer of zinc oxide film with low hydroxyl content makes the quantum dot light-emitting diode device continue to work to a stable state.
  • the carrier injection equilibrium state can be achieved, thereby obtaining a good device lifetime.
  • the second electron transport layer is a zinc oxide film with surface hydroxyl groups less than or equal to 0.4
  • the third electron transport layer is selected from metal-doped zinc oxide films
  • the second electron transport layer is combined with the first electron transport layer
  • the third electron transport layer is combined on the side surface of the second electron transport layer away from the first electron transport layer.
  • a zinc oxide film containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface and a metal-doped zinc oxide film can reduce the amount of injection into the quantum dot light-emitting layer.
  • the electrons in the quantum dot light-emitting diode device realize the injection balance of carriers in the quantum dot light-emitting diode device, and finally make the quantum dot light-emitting diode have a high external quantum efficiency in the early stage of operation; and a layer of zinc oxide film with low hydroxyl content makes the quantum dot light-emitting diode.
  • the device can also reach a carrier injection equilibrium state when it continues to work to a stable state, thereby obtaining a good device lifetime.
  • the obtained quantum dot light-emitting diode device has both good EQE and period lifetime.
  • the second electron transport layer is a zinc oxide film with a surface hydroxyl amount of less than or equal to 0.4
  • the third electron transport layer is a zinc oxide film with a surface hydroxyl amount of less than or equal to 0.4
  • the first electron transport layer is disposed on One side surfaces of the second electron transport layer and the third electron transport layer.
  • a zinc oxide film with a zinc oxide film containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface can reduce the electrons injected into the light-emitting layer of quantum dots and realize quantum dots.
  • the injection balance of carriers in the dot light-emitting diode device finally makes the quantum dot light-emitting diode have a high external quantum efficiency in the early stage of operation; and the two-layer zinc oxide film with low hydroxyl content makes the quantum dot light-emitting diode device continue to work until In the steady state, the carrier injection equilibrium state can also be achieved, thereby obtaining a good device lifetime.
  • the zinc oxide solution with less surface hydroxyl groups is deposited on the quantum dot light-emitting layer, it is beneficial to obtain a more flat zinc oxide film.
  • the obtained quantum dot light-emitting diode device has both good EQE and period lifetime.
  • the electron transport layer 50 includes a first electron transport layer 51 , a second electron transport layer 52 and a third electron transport layer 53 , wherein the first electron transport layer 51 is a surface containing carbon atoms. It is a zinc oxide film with 8-18 amino ligands and/or carboxyl ligands, the second electron transport layer 52 is a zinc oxide film with a surface hydroxyl amount less than or equal to 0.4, and the third electron transport layer 53 is a surface hydroxyl amount less than or equal to 0.4. or equal to 0.4 of the zinc oxide thin film, the third electron transport layer 53 is provided on the surface of the first electron transport layer 51 on the side away from the second electron transport layer 52 .
  • the zinc oxide in the zinc oxide film with the surface hydroxyl content of less than or equal to 0.4 is undoped zinc oxide, or it can be Metal-doped zinc oxide; similarly, the zinc oxide in the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 may be undoped zinc oxide or metal-doped zinc oxide.
  • the electron transport layer has a thickness of 10-100 nm. Due to the zinc oxide films containing amine ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface, zinc oxide films with surface hydroxyl groups greater than or equal to 0.6, or metal-doped zinc oxide films, their electron mobility is relatively high. Therefore, the film thickness is relatively thin; the zinc oxide film with a surface hydroxyl content of less than or equal to 0.4 has a relatively thick film thickness due to its high electron mobility.
  • the thickness of the zinc oxide thin film containing amine ligands and/or carboxyl ligands with 8-18 carbon atoms on the surface is 10-80 nm. In some embodiments, the thickness of the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 is 10-30 nm. In some embodiments, the thickness of the metal-doped zinc oxide film is 10-30 nm. The thickness of each layer is within this range, so that in this case, the thickness of the zinc oxide film is suitable, and it is not easy to be broken down by electrons, which is conducive to maintaining the injection performance, film formation quality and surface flatness of the electron transport layer.
  • the electron transport layer includes a second electron transport layer, and the second electron transport layer is an embodiment of a metal-doped zinc oxide film, and the electron transport layer includes a second electron transport layer and a third electron transport layer, and the second electron transport layer and/or in the embodiment in which the third electron transport layer is a metal-doped zinc oxide film, in some embodiments, the type of doping metal in the metal-doped zinc oxide film, the effect of the doping metal, and the doping
  • the doping content of the metal is as described above (in the case where the electron transport layer is the first electron transport layer).
  • the doping metal in the metal-doped zinc oxide thin film is selected from at least one of Mg 2+ and Mn 2+ . In some embodiments, the doping metal in the metal-doped zinc oxide film is selected from at least one of Al 3+ , Y 3+ , La 3+ , Li + , Gd 3+ , Zr 4+ , Ce 4+ .
  • the doping amount of the doping metal ions is referred to above, and is not repeated here.
  • the above-mentioned two quantum dot light-emitting diodes provided in the examples of this application (one is that the electron transport layer includes a first electron transport layer, and the first electron transport layer is that the amount of surface hydroxyl groups is greater than or equal to 0.6
  • the electron transport layer contains zinc oxide, and at least part of the surface of the zinc oxide contains amine ligands and/or carboxyl ligands with carbon atoms of 8-18) as shown in Figure 3
  • the quantum The point light emitting diode includes an anode 10 and a cathode 60 disposed opposite to each other, a quantum dot light emitting layer 40 disposed between the cathode 60 and the anode 10 , and an electron transport layer 50 disposed between the cathode 60 and the quantum dot light emitting layer 40 .
  • the light emitting diode further includes a hole functional layer disposed between the anode 10 and the quantum dot light emitting layer 40 .
  • the hole functional layer includes at least one of a hole transport layer, a hole injection layer and an electron blocking layer.
  • the quantum dot light emitting diode further includes an electron injection layer disposed between the cathode 60 and the electron transport layer 50 .
  • the light emitting diode may further include a substrate, and the anode 10 or the cathode 60 is disposed on the substrate.
  • the light-emitting diodes provided in the embodiments of the present application are classified into upright light-emitting diodes and inverted light-emitting diodes.
  • the upright quantum dot light-emitting diode includes an anode 10 and a cathode 60 disposed opposite to each other, a quantum dot light-emitting layer 40 disposed between the anode 10 and the cathode 60, and a quantum dot light-emitting layer 40 disposed between the cathode 60 and the quantum dot light-emitting layer 40
  • the electron transport layer 50 in between, and the anode 10 is disposed on the substrate.
  • a hole transport layer 30 is disposed between the anode 10 and the quantum dot light-emitting layer 40, further, a hole injection layer 20 is disposed between the anode 10 and the hole transport layer; and/or, a cathode An electron injection layer is provided between 60 and the electron transport layer 50 .
  • the quantum dot light emitting diode includes a substrate 100, an anode 10 disposed on the surface of the substrate 100, a hole injection layer 20 disposed on the surface of the anode 10, and disposed on the surface of the anode 10.
  • the inverted quantum dot light-emitting diode includes a stacked structure including an anode 10 and a cathode 60 disposed opposite to each other, a quantum dot light-emitting layer 40 disposed between the anode 10 and the cathode 60, and a quantum dot light-emitting layer 40 disposed between the cathode 60 and the quantum
  • the electron transport layer 50 between the point light-emitting layers 40, and the cathode 60 are provided on the substrate.
  • a hole transport layer 30 is disposed between the anode 10 and the quantum dot light-emitting layer 40, further, a hole injection layer 20 is disposed between the anode 10 and the hole transport layer; and/or, a cathode An electron injection layer is provided between 60 and the electron transport layer 50 .
  • the quantum dot light emitting diode includes a substrate 100, a cathode 60 disposed on the surface of the substrate 100, an electron transport layer 50 disposed on the surface of the cathode 60, and an electron transport layer 50 disposed on the surface of the cathode 60.
  • the substrate 100 may be a rigid substrate or a flexible substrate, and specifically, glass, silicon wafer, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate can be selected.
  • the material of the hole injection layer 20 can be selected from at least one of poly(ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), HTL-1, HTL-2, Of course, other hole injection materials with high injection performance can also be used.
  • PEDOT:PSS The structure of PEDOT:PSS is as follows:
  • HTL-1 The structure of HTL-1 is as follows:
  • HTL-2 The structure of HTL-2 is as follows:
  • the material of the hole transport layer 30 can be selected from conventional hole transport materials.
  • the material of the hole transport layer 30 includes 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), poly[(9,9'-dioctylfluorene-2,7- Diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))](TFB), poly(4-butylphenyl-diphenylamine)(poly- At least one of TPD), 4,4',4'-tris(N-carbazolyl)-triphenylamine (TCTA), poly(N-vinylcarbazole) (PVK) and derivatives thereof, of course,
  • the material of the hole transport layer 30 can also be other hole transport materials with high injection performance.
  • the quantum dots in the quantum dot light-emitting layer 40 are one kind of quantum dots of red, green and blue, and can also be yellow light quantum dots.
  • the quantum dots may be cadmium-containing or cadmium-free.
  • the quantum dots in the quantum dot light-emitting layer 40 may be single-core quantum dots or core-shell quantum dots, and the core and shell compounds of the quantum dots may be independently selected from CdS, CdSe, CdTe, ZnO, ZnS , ZnSe, ZnTe, GaAs, GaP, GaSb, HgS, HgSe, HgTe, InAs, InP, InSb, AlAs, AlP, CuInS, CuInSe, and at least one of various core-shell structure quantum dots or alloy structure quantum dots.
  • the quantum dot light-emitting layer thus formed has the characteristics of wide and continuous distribution of excitation spectrum and high stability of emission spectrum.
  • the material and thickness of the electron transport layer 50 are as described above, and details are not repeated here.
  • the thickness of the electron transport layer is 10-100 nm.
  • the thickness of the electron transport layer is less than 10nm, the film layer is easily broken down by electrons, and it is difficult to ensure the injection performance of carriers; when the thickness of the electron transport layer is greater than 100nm, it will hinder the injection of electrons and affect the charge injection of the device balance.
  • the bottom electrode (the anode 10 combined on the substrate 100 or the cathode 60 combined on the substrate) can be made of common bottom electrode materials.
  • the material of the bottom electrode includes zinc oxide, indium oxide, tin oxide, At least one of indium tin oxide (ITO), indium zinc oxide (IZO), and fluorine-doped tin oxide.
  • the top electrode (anode 10 or cathode 60 remote from substrate 100) is a transparent oxide, a thin metal, or a combination of both.
  • the transparent oxide may be ITO, IZO, AZO;
  • the thin metal may be Ag, Al, Au, Mg, Ca, Yb, Ba, or alloys thereof; in some embodiments , the top electrode can also be O/M/O, wherein M is Ag, Al, Au, Mg, Ca, Yb, Ba or their alloys, and O is oxide, including but not limited to ITO, IZO, AZO.
  • the electron mobility of the electron transport layer is reduced, the transport of electrons in the electron transport layer is suppressed, and the transport of electrons in the quantum dot light-emitting diode is reduced, thereby reducing the electrons injected into the quantum dot light-emitting layer and realizing the mid-load loading of the quantum dot light-emitting diode.
  • the injection of the current is balanced, and finally a quantum dot light-emitting diode with higher external quantum efficiency is obtained.
  • the preparation method of the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 includes:
  • a zinc oxide colloidal solution is prepared by a solution method as a film-forming solution for a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6.
  • the obtained precipitate is washed twice or less with a reaction solvent to obtain zinc oxide with a surface hydroxyl amount greater than or equal to 0.6.
  • the solvent used for dissolving or diluting the alkali to form the first alkali solution can dissolve the alkali or be miscible with the alkali, in addition, the solvent has the same polarity as the zinc oxide nanoparticles.
  • the solvent used to dissolve or dilute the base to form the first lye solution may be the same as the solvent in the zinc salt solution, or may be different from the solvent in the zinc salt solution.
  • the solvent used for dissolving or diluting the alkali to form the first alkali solution is selected from the same solvent as the zinc salt solution, which is more conducive to obtaining a stable reaction system.
  • the reaction temperature between the zinc salt solution and the first alkali solution is room temperature to 50° C.
  • the zinc salt solution is mixed with the first lye solution at a temperature of 0-30°C, and a qualified zinc oxide colloid solution can be easily generated; in some embodiments, the temperature is 30°C Under the condition of ⁇ 70°C, zinc oxide colloidal solution can also be generated, and the quality of the obtained zinc oxide colloidal solution is not as good as the zinc oxide colloidal solution generated under the condition of 0 ⁇ 30°C, and the reaction time should also be shortened.
  • the zinc salt solution in the step of mixing the zinc salt solution with the first lye solution, is mixed with the first alkali solution according to the molar ratio of hydroxide ions to zinc ions in a ratio of 1.5:1 to 2.5:1.
  • the lye mixing treatment ensures the formation of zinc oxide nanoparticles and reduces the formation of reaction by-products.
  • the addition amount of the zinc salt solution and the first lye solution satisfies: the molar amount of hydroxide ions provided by the first lye solution and the zinc salt
  • the molar ratio of the provided zinc ions is 1.7:1 to 1.9:1.
  • the reaction is carried out at a reaction temperature of 0-70° C. for 30 minutes to 4 hours to ensure the formation of zinc oxide nanoparticles and to control the particle size of the nanoparticles.
  • the reaction time is less than 30min, the reaction time is too low to obtain the cluster seeds of zinc oxide.
  • the crystalline state of the sample is incomplete and the crystal structure is poor. If it is used as an electron transport layer material, it will The conductivity of the electron transport layer is very poor; when the reaction time exceeds 4h, the long particle growth time makes the generated nanoparticles too large and the particle size is uneven, and the surface roughness of the zinc oxide colloid solution after film formation will be higher. high, which affects the transport properties of electrons.
  • the reaction is carried out at the reaction temperature for 1-2 hours.
  • the zinc salt solution is mixed with the first lye solution at a temperature of 0 to 70°C, and the reaction is carried out for 30 min to 4 h under stirring conditions to promote the uniformity of the reaction and the resulting oxidation Particle uniformity of zinc nanoparticles to obtain zinc oxide nanoparticles of uniform size.
  • a precipitating agent is added to the mixed solution after the reaction is completed, and the precipitate is collected.
  • the precipitant selects a solvent of opposite polarity to the final product zinc oxide nanoparticles, thereby precipitating the zinc oxide nanoparticles by reducing their solubility.
  • the precipitant selects a solvent with a weaker polarity, which is opposite to the polarity of the zinc oxide nanoparticles, which is favorable for the precipitation of the zinc oxide nanoparticles.
  • precipitants include, but are not limited to, ethyl acetate, acetone, n-hexane, n-heptane, and other low-polarity long-chain alkanes, etc.
  • the volume ratio of the precipitant to the mixed solution is 2:1 to 6:1
  • a white precipitate is generated in the mixed solution .
  • the volume ratio of the precipitant to the mixed solution is 3:1 to 5:1.
  • the precipitation-treated mixed system is centrifuged to collect the precipitate.
  • a reaction solvent is used to wash the collected precipitate to remove reactants that do not participate in the reaction.
  • Using the reaction solvent to clean the obtained zinc oxide nanoparticles can remove the excess zinc salt, alkali and other raw materials for preparing the zinc oxide nanoparticles, so as to improve the purity of the zinc oxide nanoparticles.
  • the reaction solvent is as described above.
  • the reaction solvent is selected from at least one of water, organic alcohols, organic ethers, and sulfones.
  • the reaction solvent is selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and DMSO.
  • the zinc salt reacts with alkali to form zinc oxide nanoparticles in the embodiments of the present application
  • a large number of ionized hydroxyl groups are adsorbed on the surface thereof. These hydroxyl groups are negatively charged, and a large number of them are adsorbed on the surface of the zinc oxide nanoparticles, so that the surface of the zinc oxide nanoparticles is also negatively charged.
  • electrostatic Coulomb repulsion between ZnO nanoparticles ZnO nanoparticles can be dispersed in polar solution, and have good solution stability and dispersibility.
  • the zinc oxide colloid solution After the zinc oxide colloid solution is deposited into a zinc oxide film, a large number of hydroxyl groups will still coat the surface of the cured zinc oxide particles.
  • this zinc oxide film is used as the electron transport layer in the quantum dot light-emitting diode structure, the electron transport in the zinc oxide layer will be inhibited to a certain extent due to the adsorption of a large number of negatively charged hydroxyl groups on the surface of the zinc oxide. Therefore, the amount of hydroxyl groups on the surface of the zinc oxide film will directly affect the injection of electrons in the quantum dot light-emitting diode device.
  • the amount of surface hydroxyl groups of the zinc oxide nanoparticles obtained is adjusted by controlling the number of cleanings.
  • the reaction solvent is used to clean the precipitate twice or less, so that the amount of hydroxyl groups on the surface is greater than or equal to 0.6.
  • the alkali in the first alkali solution is an alkali with K b >10 -1
  • the number of cleaning treatments is less than or equal to 2 times.
  • the amount of hydroxyl groups on the surface of the zinc oxide colloid finally synthesized is large, and the high hydroxyl groups on the surface of zinc oxide can be maintained after cleaning less than or equal to 2 times. quantity status.
  • the number of cleaning treatments is less than or equal to 1 time.
  • the reaction base is a base with K b ⁇ 10 -1
  • the amount of hydroxyl groups on the surface of the final synthesized zinc oxide colloid is small, so the number of cleaning times is less than or equal to one time to achieve more surface amount of hydroxyl groups.
  • bases with K b >10 -1 include but are not limited to inorganic strong bases such as potassium hydroxide, sodium hydroxide, lithium hydroxide, etc.; bases with K b ⁇ 10 -1 include but are not limited to TMAH, ammonia, ethanolamine, Organic weak bases such as ethylenediamine.
  • the alkali in the first alkali solution is selected from at least one of potassium hydroxide, sodium hydroxide, and lithium hydroxide, and the number of times that the collected precipitate is cleaned with a reaction solvent is 1 time, Zinc oxide nanoparticles with surface hydroxyl groups greater than or equal to 0.6 can be obtained; in some embodiments, the alkali in the first alkali solution is selected from at least one of TMAH, ammonia water, ethanolamine, and ethylenediamine, and a reaction solvent is used to collect The number of times that the obtained precipitate is washed is one time, and zinc oxide nanoparticles with a surface hydroxyl group amount greater than or equal to 0.6 can be obtained.
  • the zinc oxide film with surface hydroxyl groups greater than or equal to 0.6 is a metal-doped zinc oxide film, and correspondingly, the zinc oxide film with surface hydroxyl groups greater than or equal to 0.6 is metal-doped zinc oxide.
  • the zinc salt solution also contains doping metal ions.
  • the type of doping metal in the metal-doped zinc oxide film, the effect of the doping metal, and the doping content of the doping metal are as described above (the case where the electron transport layer is the first electron transport layer), in order to save space , and will not be repeated here.
  • the doping metal in the metal-doped zinc oxide thin film is selected from at least one of Mg 2+ and Mn 2+ . In some embodiments, the doping metal in the metal-doped zinc oxide film is selected from at least one of Al 3+ , Y 3+ , La 3+ , Li + , Gd 3+ , Zr 4+ , Ce 4+ .
  • the doping amount of the doping metal ions is referred to above, and is not repeated here.
  • the zinc salt solution contains zinc ions and doped metal ions
  • the addition amount of the zinc salt solution and the first lye solution satisfies:
  • the ratio of the product of the molar amount and the valence number to the molar amount of hydroxide ions is 0.75:1 to 1.25:1.
  • the addition amount of the zinc salt solution and the first lye solution satisfies the product of the molar amount of metal ions and the valence number and the mole of hydroxide ions
  • the ratio of quantity is 0.85:1 ⁇ 0.95:1.
  • the above-mentioned zinc oxide colloid solution can be formed on the prefabricated device substrate by adopting, but not limited to, a spin coating method, a blade coating method, a printing method, a spray coating method, a roller coating method, an electrodeposition method, and the like. kind.
  • the solvent is removed by annealing treatment to obtain a zinc oxide film with surface hydroxyl groups greater than or equal to 0.6.
  • the quantum dot light-emitting diode is an upright quantum dot light-emitting diode
  • the prefabricated device substrate includes an anode substrate, and a quantum dot light-emitting layer combined on the anode substrate.
  • the prefabricated device substrate further includes a hole functional layer disposed between the anode substrate and the quantum dot light-emitting layer.
  • the hole functional layer includes at least one of a hole transport layer, a hole injection layer and an electron blocking layer.
  • the quantum dot light emitting diode is an inverted quantum dot light emitting diode
  • the prefabricated device substrate is a cathode substrate.
  • the prefabricated device substrate further includes an electron injection layer bonded to the cathode surface of the cathode substrate.
  • a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 can be used alone as an electron transport layer.
  • the second electron transport layer is a zinc oxide film with surface hydroxyl groups less than or equal to 0.4, or the second electron transport layer is a metal-doped zinc oxide film.
  • the first electron transport layer may be disposed on the side adjacent to the quantum dot light-emitting layer, or may be disposed on the side adjacent to the cathode.
  • the second electron transport layer is disposed on the side adjacent to the quantum dot light-emitting layer or the metal-doped zinc oxide film is disposed on the side adjacent to the quantum dot light-emitting layer, so that a more flat zinc oxide film can be obtained.
  • the electron transport layer includes three zinc oxide films, named as the first electron transport layer, the second electron transport layer and the third electron transport layer, respectively.
  • at least the first electron transport layer is a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 prepared by the above-mentioned method.
  • the second electron transport layer and the third electron transport layer please refer to the electron transport layer in the quantum dot light-emitting diode device above. The case where the transport layer includes the third electron transport layer.
  • the zinc oxide film with the surface hydroxyl content of less than or equal to 0.4 can be formed by the zinc oxide colloidal solution with the surface hydroxyl content of less than or equal to 0.4.
  • the metal-doped zinc oxide film can be prepared according to the following method:
  • the addition amount of the alkali satisfies: the ratio of the product of the molar amount of the metal ion and the valence number to the molar amount of the hydroxide ion is 0.75:1 ⁇ 1.25:1.
  • an embodiment of the present application provides a method for preparing a quantum dot light-emitting diode, the quantum dot light-emitting diode comprises an anode and a cathode arranged oppositely, a quantum dot light-emitting layer arranged between the anode and the cathode, arranged on the An electron transport layer between the quantum dot light-emitting layer and the cathode, wherein the electron transport layer includes a first electron transport layer, and the first electron transport layer is a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6;
  • the preparation method of the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 includes:
  • the transport of electrons to the quantum dot light-emitting layer is inhibited, the electrons injected into the quantum dot light-emitting layer are reduced, and the holes in the quantum dot light-emitting diode are reduced. Electron injection is more balanced, resulting in improved device lifetime.
  • the method for preparing zinc oxide colloidal solution by solution method in above-mentioned step S21, the selection basis and type of zinc salt solution, zinc salt in zinc salt solution and solvent, and the formation mode of zinc salt solution, first lye solution, first lye solution The selection basis and type of the base and solvent in , and the formation method of the first alkali solution are as described in step S11 of the above-mentioned first embodiment. In order to save space, they will not be repeated here.
  • a precipitant is added to the mixed solution after the reaction is completed, and the precipitate is collected.
  • the precipitant refer to the above-mentioned first embodiment.
  • the washed precipitate is dissolved to obtain a zinc oxide colloid solution.
  • the second alkaline solution is added to the zinc oxide colloidal solution to adjust the pH of the zinc oxide colloidal solution to be greater than or equal to 8.
  • the hydroxyl ligands on the zinc oxide surface and the ionized hydroxyl groups in the zinc oxide colloid solution constitute a dynamic equilibrium, and the addition of the second alkali solution above will break this equilibrium.
  • the amount of hydroxyl ligands on the surface of zinc oxide will also increase correspondingly due to the increase in the amount of hydroxyl groups in the ionized state of the zinc oxide colloidal solution.
  • the pH of the zinc oxide colloid solution is adjusted to be between 9 and 12 by adding a second alkali solution, and on the basis of making the amount of hydroxyl groups on the surface of the obtained zinc oxide greater than or equal to 0.6, the zinc oxide can also be Nanoparticles have higher yields (concentrations).
  • the pH of the zinc oxide colloidal solution is adjusted to be between 9 and 10 by adding a second alkali solution.
  • the alkali in the second alkali solution can be selected from inorganic bases or organic bases; strong bases can also be selected from weak bases.
  • the second alkali solution is selected from the second alkali solution formed by at least one of potassium hydroxide, sodium hydroxide, lithium hydroxide, TMAH, ammonia water, ethanolamine, and ethylenediamine.
  • the second alkali solution is a solution formed by dissolving an inorganic base or a solution formed by dissolving or diluting an organic base.
  • the concentration of the second alkali solution is adjusted, so as to control the reaction rate, so that the adjustment of the hydroxyl groups on the surface of the zinc oxide nanoparticles can be fully performed.
  • the solvent used for dissolving or diluting the acid to form the second alkali solution can dissolve or be miscible with the alkali, and the solvent has the same polarity as the zinc oxide nanoparticles.
  • the solvent used to dissolve or dilute the base to form the second lye can be the same as the solvent in the zinc salt solution, or it can be different from the solvent in the zinc salt solution.
  • the solvent used for dissolving or diluting the alkali to form the second alkali solution includes, but is not limited to, water, organic alcohol, organic ether, sulfone and other solvents with relatively high polarity.
  • the solvent is selected from at least one of water, organic alcohols, organic ethers, and sulfones.
  • the solvent can be selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and dimethyl sulfoxide (DMSO).
  • the zinc salt solution contains zinc ions and doped metal ions
  • the addition amount of the zinc salt solution and the first lye solution satisfies:
  • the ratio of the product of the molar amount and the valence number to the molar amount of hydroxide ions is 0.75:1 to 1.25:1.
  • the addition amount of the zinc salt solution and the first lye solution satisfies the product of the molar amount of metal ions and the valence number and the mole of hydroxide ions
  • the ratio of quantity is 0.85:1 ⁇ 0.95:1.
  • the above zinc oxide solution can be formed on the prefabricated device substrate of the zinc oxide film whose surface hydroxyl content is greater than or equal to 0.6, and the solvent can be removed to obtain the surface hydroxyl content.
  • step S22 refers to the above-mentioned first implementation.
  • the examples of the present application provide a method for preparing a quantum dot light-emitting diode, the quantum dot light-emitting diode comprises an anode and a cathode arranged oppositely, a quantum dot light-emitting layer arranged between the anode and the cathode, arranged on the An electron transport layer between the quantum dot light-emitting layer and the cathode, wherein the electron transport layer includes a first electron transport layer, and the first electron transport layer is a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6;
  • the preparation method of the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 includes:
  • an alkali treatment is performed on a zinc oxide prefabricated film, and a liquid film is formed on the surface of the zinc oxide film, so that the amount of hydroxyl groups on the surface of the zinc oxide prefabricated film is formed by the alkali content in the liquid film.
  • Dynamic balance and then increase the amount of hydroxyl groups on the surface of the zinc oxide prefabricated film, so as to obtain zinc oxide with a surface hydroxyl amount greater than or equal to 0.6.
  • the transport of electrons to the quantum dot light-emitting layer is suppressed, and the number of electrons injected into the quantum dot light-emitting layer is reduced, so that the quantum dots Hole-electron injection in light-emitting diodes is more balanced, resulting in improved device lifetime.
  • the composition of the quantum dot light-emitting diode is as in the first aspect above. In order to save space, it is not repeated here.
  • the zinc oxide prefabricated film can be prepared in various ways, for example, the zinc oxide prefabricated film is prepared by a solution method or a sol-gel method.
  • the prefabricated zinc oxide film is prepared by a solution method, including: mixing and reacting a zinc salt solution with a first alkali solution to prepare zinc oxide nanoparticles; dissolving the zinc oxide nanoparticles to obtain a zinc oxide colloidal solution; A zinc oxide colloid solution is formed on a prefabricated device substrate of a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 to be prepared, and the solvent is removed to prepare a zinc oxide prefabricated film.
  • the above zinc oxide colloidal solution can be formed on the prefabricated device substrate of the zinc oxide film with the surface hydroxyl content greater than or equal to 0.6 to be prepared, and the solvent can be removed to prepare the surface Zinc oxide film with hydroxyl content greater than or equal to 0.6.
  • the amount of hydroxyl groups on the surface of the zinc oxide prefabricated film is changed by depositing the second alkali solution on the zinc oxide prefabricated film. Specifically, after the second alkali solution is deposited, a liquid film will be formed on the surface of the zinc oxide prefabricated film. Therefore, the hydroxyl groups on the surface of the zinc oxide prefabricated film will form a dynamic balance with the alkali content in the liquid film, thereby increasing the hydroxyl groups on the surface of the zinc oxide prefabricated film. quantity.
  • the alkali in the second alkali solution can be selected from inorganic bases or organic bases; strong bases can also be selected from weak bases.
  • the second alkali solution is selected from the second alkali solution formed by at least one of potassium hydroxide, sodium hydroxide, lithium hydroxide, TMAH, ammonia water, ethanolamine, and ethylenediamine.
  • the second alkali solution is a solution formed by dissolving an inorganic base or a solution formed by dissolving or diluting an organic base.
  • the solvent used for dissolving or diluting the alkali to form the second alkali solution includes, but is not limited to, water, organic alcohol, organic ether, sulfone and other solvents with relatively high polarity.
  • the solvent is selected from at least one of water, organic alcohols, organic ethers, and sulfones.
  • the solvent can be selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and dimethyl sulfoxide (DMSO).
  • the deposition amount of the second alkali solution and the weight of the underlying zinc oxide prefabricated film satisfy: every 5 mg of the zinc oxide prefabricated film is treated with 50 ⁇ L-1000 ⁇ L of the second alkali solution. If the concentration of the second lye solution and the amount of alkali added are too large, a large amount of zinc hydroxide impurities will be produced on the surface of the zinc oxide prefabricated film, which will affect the quality of the zinc oxide film. It is not easy to play the role of increasing the amount of hydroxyl groups on the surface of zinc oxide. It should be understood that the concentration of the second alkali solution can be flexibly adjusted according to different types of alkali selected.
  • Inorganic bases are generally strong bases, and the ionization ability of hydroxide ions is strong, so only a small amount of inorganic bases at low concentrations can adjust the amount of hydroxyl groups on the surface of zinc oxide.
  • the organic bases are generally weak bases, and the hydroxide ion ionization ability is weak, so a relatively high concentration of a large amount of organic bases is required to effectively adjust the amount of hydroxyl groups on the surface of zinc oxide.
  • the alkali in the second alkali solution is an inorganic alkali, and the concentration of the second alkali solution is 0.05-0.1 mmol/L.
  • the inorganic base is selected from at least one of potassium hydroxide, sodium hydroxide, and lithium hydroxide.
  • the deposition amount of the second alkali solution and the weight of the underlying zinc oxide prefabricated film satisfy: every 5 mg of the zinc oxide prefabricated film is treated with 50 ⁇ L-400 ⁇ L of the second alkali solution.
  • the alkali in the second alkali solution is an organic alkali, and at this time, the concentration of the corresponding second alkali solution is 0.2-0.4 mmol/L.
  • the organic carboxylic acid is selected from at least one of TMAH, ammonia water, ethanolamine, and ethylenediamine.
  • the deposition amount of the second alkali solution and the weight of the underlying zinc oxide prefabricated film satisfy: every 5 mg of the zinc oxide prefabricated film is treated with 500 ⁇ L-1000 ⁇ L of the second alkali solution.
  • the method for depositing the second alkali solution on the surface of the zinc oxide prefabricated film may adopt a solution processing method, including but not limited to spin coating method, blade coating method, printing method, spraying method, roller coating method, electrodeposition one of the laws.
  • the drying temperature ranges from 10°C to 50°C, and the drying time ranges from 30 minutes to 2 hours.
  • the electron transport layer includes three zinc oxide films, named as the first electron transport layer, the second electron transport layer and the third electron transport layer, respectively.
  • at least the first electron transport layer is a zinc oxide film with a surface hydroxyl amount greater than or equal to 0.6 prepared by the above-mentioned method.
  • the second electron transport layer and the third electron transport layer please refer to the electron transport layer in the quantum dot light-emitting diode device above. The case where the transport layer includes the third electron transport layer.
  • the zinc oxide film with the surface hydroxyl content of less than or equal to 0.4 can be formed by the zinc oxide colloidal solution with the surface hydroxyl content of less than or equal to 0.4.
  • the metal-doped zinc oxide film can be prepared by referring to the method for the metal-doped zinc oxide film provided by the first implementation method.
  • the preparation of metal-doped zinc oxide films includes:
  • the type of doping metal in the metal-doped zinc oxide film, the effect of the doping metal, and the doping content of the doping metal are as described above (the case where the electron transport layer is the first electron transport layer), in order to save space , and will not be repeated here.
  • the doping metal in the metal-doped zinc oxide thin film is selected from at least one of Mg 2+ and Mn 2+ . In some embodiments, the doping metal in the metal-doped zinc oxide film is selected from at least one of Al 3+ , Y 3+ , La 3+ , Li + , Gd 3+ , Zr 4+ , Ce 4+ .
  • the doping amount of the doping metal ions is referred to above, and is not repeated here.
  • the method for forming the hole functional layer (including at least one of the hole injection layer, the hole transport layer and the electron blocking layer) and the quantum dot light-emitting layer preferably adopts a solution processing method, including but not limited to One of the spin coating method, blade coating method, printing method, spray method, roller coating method, electrodeposition method, etc.
  • an example of the present application provides a method for preparing a quantum dot light-emitting diode.
  • the quantum dot light-emitting diode includes a quantum dot light-emitting diode including an anode and a cathode disposed opposite to each other, and a quantum dot disposed between the anode and the cathode.
  • the preparation method of the first electron transport layer is:
  • a zinc oxide colloid solution is formed on the prefabricated device substrate on which the first electron transport layer is to be prepared, and the solvent is removed to prepare the first electron transport layer.
  • the preparation method of the quantum dot light-emitting diode provided in the embodiment of the present application, by adding amine ligands and/or carboxyl ligands with 8-18 carbon atoms in the process of synthesizing the zinc oxide colloidal solution, so that the amine ligands and /or the carboxyl ligand and the hydroxyl ligand on the surface of the zinc oxide colloid perform ligand exchange, and then the amine ligand and/or the carboxyl ligand with a carbon number of 8-18 are coordinated on the surface of the zinc oxide colloid.
  • the ZnO nanoparticles in solution and after film formation are increased.
  • the distance between them thereby reducing the electron mobility of the electron transport layer, inhibiting the transport of electrons in the electron transport layer, and reducing the transport of electrons in the quantum dot light-emitting diode, thereby reducing the electrons injected into the quantum dot light-emitting layer and realizing the quantum dots.
  • the injection of carriers in the dot light-emitting diode is balanced, and finally a quantum dot light-emitting diode with higher external quantum efficiency is obtained.
  • the composition of quantum dot light-emitting diodes especially in the case of the electron transport layer, the selection of amine ligands and/or carboxyl ligands with 8-18 carbon atoms and the selection of amine-based ligands and/or carboxyl ligands with 8-18 carbon atoms
  • the thickness of the zinc oxide thin film of the amine ligand and/or carboxyl ligand of 18 is the same as in the first aspect above. In order to save space, it will not be repeated here.
  • step S41 the basic process of preparing zinc oxide by solution method is as follows: mixing zinc salt solution with lye, reacting to generate hydroxide intermediates such as zinc hydroxide; the hydroxide intermediate undergoes polycondensation reaction to gradually generate zinc oxide nanoparticles .
  • the electron mobility of the post-zinc oxide electron transport layer actually plays the same role as the amount of hydroxyl groups on the surface of the zinc oxide film is greater than or equal to 0.6.
  • an amino ligand and/or a carboxyl ligand with a carbon number of 8-18 are added, that is, an amino ligand with a carbon number of 8-18 and /or the carboxyl ligand and lye are added to the zinc salt solution at the same time.
  • the steps of preparing the zinc oxide colloidal solution by the solution method include:
  • the zinc salt solution, lye and amine ligands and/or carboxyl ligands with a carbon number of 8-18 are mixed and reacted to prepare the amino ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface.
  • the zinc oxide nanoparticles are dissolved to obtain a zinc oxide colloidal solution.
  • the zinc salt solution is a salt solution formed by dissolving the zinc salt in a solvent.
  • the zinc salt is selected from the salt that can react with the lye to generate zinc hydroxide, including but not limited to one of zinc acetate, zinc nitrate, zinc sulfate, and zinc chloride.
  • the solvent is selected to have solubility for the zinc salt, including but not limited to water, organic alcohols, organic ethers, sulfones and other solvents with relatively high polarity.
  • the solvent is selected from at least one of water, organic alcohols, organic ethers, and sulfones.
  • the solvent can be selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and dimethyl sulfoxide (DMSO).
  • DMSO dimethyl sulfoxide
  • the alkaline solution is a solution formed by an alkali capable of reacting with a zinc salt to generate zinc hydroxide.
  • the lye is obtained by solvent dissolution or dilution.
  • the alkali in the alkali solution can be selected from inorganic bases or organic bases.
  • the alkali in the alkali solution is an inorganic alkali, and exemplarily, the inorganic alkali is selected from at least one of potassium hydroxide, sodium hydroxide, and lithium hydroxide.
  • the base in the alkali solution is an organic base, and exemplarily, the weak base is selected from at least one of TMAH, ammonia water, ethanolamine, and ethylenediamine.
  • the solvent used to dissolve or dilute the alkali to form the lye solution may be the same as the solvent in the zinc salt solution, or may be different from the solvent in the zinc salt solution.
  • the solvent used for dissolving or diluting the alkali to form the alkali solution is selected from the same solvent as the zinc salt solution, which is more beneficial to obtain a stable reaction system.
  • the same solvent includes, but is not limited to, water, organic alcohol, organic ether, sulfone and other solvents with relatively high polarity.
  • the solvent is selected from at least one of water, organic alcohols, organic ethers, and sulfones.
  • the solvent can be selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and dimethyl sulfoxide (DMSO).
  • amine ligands and/or carboxyl ligands having 8-18 carbon atoms include, but are not limited to, octanoic acid, octylamine, dodecanoic acid, dodecylamine, oleic acid, and oleylamine.
  • amine ligands and/or carboxyl ligand having a carbon number of 8-18 is configured into a ligand solution, it is mixed and reacted with a zinc salt solution and an alkaline solution.
  • a solvent with greater polarity mainly considering the solubility of the reaction raw materials and products.
  • the solvent in the ligand solution is selected from at least one of methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and DMSO.
  • the amine ligand and/or carboxyl ligand having 8-18 carbon atoms is a ligand solution, and the concentration of the ligand solution is 0.2-0.4 mmol/L.
  • the amount of lye added is such that the molar ratio of hydroxide ions provided by the lye to zinc ions provided by the zinc salt is 1.5:1 to 2.5:1, so as to ensure the formation of zinc oxide nanoparticles, and Reduce the formation of reaction by-products.
  • the zinc salt is significantly excessive, which makes it difficult for a large amount of zinc salt to generate zinc oxide nanoparticles; and when the molar ratio of hydroxide ion to zinc ion is greater than 2.5:1 , the lye is significantly excessive, and the excess hydroxide ion forms a stable complex with the zinc hydroxide intermediate, which is not easy to polycondensate to form zinc oxide nanoparticles.
  • the addition amounts of the zinc salt solution and the lye solution satisfy: the molar amount of hydroxide ions provided by the lye solution and the molar amount of zinc ions provided by the zinc salt The ratio of quantity is 1.7:1 ⁇ 1.9:1.
  • the addition amount of the amine ligands and/or carboxyl ligands with 8-18 carbon atoms satisfies: the amino ligands and/or carboxyl ligands with 8-18 carbon atoms and zinc salts
  • the molar ratio of the zinc salt in the solution is 1:1 to 10:1.
  • the added amine ligands and/or carboxyl ligands with a carbon number of 8-18 are bound to the surface in the resulting zinc oxide nanoparticles, thereby enabling the zinc oxide film to
  • the amine ligand and/or carboxyl ligand of -18 reduce the electron transport efficiency, thereby balancing the carrier injection balance in the quantum dot light-emitting diode, thereby helping to improve the external quantum efficiency of the device.
  • the addition amount of amine ligands and/or carboxyl ligands with carbon atoms of 8-18 is too small, there will be less long-chain ligands connected to the surface of zinc oxide, which is not easy to reduce the electron transfer efficiency and improve the EQE.
  • the electron mobility of the sample will decrease after the ligand exchange. Therefore, the electron mobility can be reduced and the EQE can be improved even if the ligand with a longer chain length is not added in a small amount.
  • the solubility of zinc oxide nanoparticles in polar solvents will be reduced, the film formation of the zinc oxide layer in the final device will be affected, and the device performance of the final device will be reduced;
  • the ligand chain length is short (8-12), the decrease of the electron mobility after ligand exchange is small, so the addition amount of the ligand with more chain length needs to be higher to achieve the purpose of improving EQE.
  • the number of carbon atoms of the amino ligand and/or the carboxyl ligand is 8-12, and the addition amount of the amino ligand and/or the carboxyl ligand satisfies: the amino ligand and/or the carboxyl ligand
  • the molar ratio of zinc salt to zinc salt solution is 4:1 ⁇ 10:1.
  • the number of carbon atoms of the amino ligand and/or the carboxyl ligand is 13-18, and the addition amount of the amino ligand and/or the carboxyl ligand satisfies: the amino ligand and/or the carboxyl ligand
  • the molar ratio of zinc salt to zinc salt solution is 1:1 ⁇ 5:1.
  • the zinc salt solution, the lye, and the amine ligand and/or carboxyl ligand having 8 to 18 carbon atoms are reacted for 30 minutes to 4 hours, In order to prepare zinc oxide nanoparticles with amine ligands and/or carboxyl ligands with carbon atoms of 8-18 bound on the surface.
  • the method of mixing the zinc salt solution and the lye solution is as follows: dissolving the zinc salt at room temperature (5°C-40°C) to obtain the zinc salt solution, dissolving or diluting the alkali at room temperature to obtain the lye solution, and at room temperature
  • a ligand solution is obtained by dissolving the amine ligand and/or carboxyl ligand with a carbon number of 8-18; the temperature of the zinc salt solution is adjusted to 0-70° C., and the alkali solution and the ligand solution are added.
  • the added alkali reacts with the zinc salt in the zinc salt solution to generate zinc oxide nanoparticles, and the added ligand is exchanged with the hydroxyl ligand on the surface of the zinc oxide nanoparticles, so that the surface is bound with a carbon atom number of 8-18 zinc oxide nanoparticles of amine ligands and/or carboxyl ligands, and can obtain good particle dispersion.
  • the reaction temperature of the zinc salt solution and the alkali solution is room temperature to 50° C. In this case, it is not only conducive to the formation of zinc oxide nanoparticles, but also the obtained zinc oxide ions have better particle dispersibility , which is beneficial to the film formation of zinc oxide colloidal solution.
  • the zinc salt solution in the step of mixing the zinc salt solution with the lye solution, is mixed with the lye solution according to the molar ratio of hydroxide ions to zinc ions in the range of 1.5:1 to 2.5:1. , to ensure the formation of ZnO nanoparticles and reduce the formation of reaction by-products.
  • the zinc salt is significantly excessive, which makes it difficult for a large amount of zinc salt to generate zinc oxide nanoparticles; and when the molar ratio of hydroxide ion to zinc ion is greater than 2.5:1 , the lye is significantly excessive, and the excess hydroxide ion forms a stable complex with the zinc hydroxide intermediate, which is not easy to polycondensate to form zinc oxide nanoparticles.
  • the addition amounts of the zinc salt solution and the lye solution satisfy: the molar amount of hydroxide ions provided by the lye solution and the molar amount of zinc ions provided by the zinc salt The ratio of quantity is 1.7:1 ⁇ 1.9:1.
  • the reaction is carried out at the reaction temperature for 30 minutes to 4 hours to ensure the formation of zinc oxide nanoparticles and to control the particle size of the nanoparticles.
  • the reaction time is less than 30 minutes, the reaction time is too short, the formation of zinc oxide nanoparticles is insufficient, and the crystallinity of the obtained nanoparticles is poor; while when the reaction time exceeds 4 h, the excessive growth time of the particles makes the resulting The nanoparticles are too large and the particle size is not uniform, which affects the later film-forming properties of the zinc oxide colloidal solution.
  • the reaction is performed for 10 minutes to 2 hours. In some embodiments, after the zinc salt solution is mixed with the alkali solution, the reaction is carried out at the reaction temperature for 1-2 hours.
  • the zinc salt solution, the lye solution, and the amine ligand and/or carboxyl ligand having 8 to 18 carbon atoms are mixed, and the reaction is stirred to promote the reaction. Homogeneity of the reaction and particle uniformity of the resulting ZnO nanoparticles.
  • a precipitant is added to the mixed solution after the reaction is completed, and the precipitate is collected.
  • the precipitant selects a solvent of opposite polarity to the final product zinc oxide nanoparticles, thereby precipitating the zinc oxide nanoparticles by reducing their solubility.
  • the precipitant selects a solvent with a weaker polarity, which is opposite to the polarity of the zinc oxide nanoparticles, which is favorable for the precipitation of the zinc oxide nanoparticles.
  • precipitating agents include, but are not limited to, ethyl acetate, acetone, n-hexane, n-heptane, and other low-polar long-chain alkanes.
  • the volume ratio of the precipitant to the mixed solution is 2:1 to 6:1
  • a white precipitate is generated in the mixed solution .
  • the volume ratio of the precipitant to the mixed solution is 3:1 to 5:1.
  • the precipitation-treated mixed system is centrifuged to collect the precipitate.
  • the collected precipitate is washed with a reaction solvent to remove reactants that do not participate in the reaction.
  • Using the reaction solvent to clean the obtained zinc oxide nanoparticles can remove the excess zinc salt, alkali and other raw materials for preparing the zinc oxide nanoparticles, so as to improve the purity of the zinc oxide nanoparticles.
  • the reaction solvent is as above.
  • the reaction solvent is selected from at least one of water, organic alcohols, organic ethers, and sulfones.
  • reaction solvents have relatively high polarity, and can effectively remove raw material impurities such as zinc salts, alkalis and other residual impurities and intermediate impurities in the zinc oxide nanoparticles.
  • the reaction solvent is selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and DMSO.
  • the washed precipitate is dissolved to obtain a zinc oxide colloid solution.
  • the amine ligand and/or carboxyl ligand with carbon atoms of 8-18 are added in the middle stage of the synthesis of the zinc oxide colloidal solution, that is, adding the lye solution to the zinc oxide precursor solution.
  • the steps of preparing the zinc oxide colloidal solution by the solution method include:
  • the zinc salt solution is mixed and reacted with the lye solution, and the amino ligands and/or carboxyl ligands with a carbon number of 8-18 are added in the reaction process to prepare an amino ligand with a carbon number of 8-18 on the surface.
  • And/or zinc oxide nanoparticles of carboxyl ligands wherein, the reaction time after adding amine ligands with 8-18 carbon atoms and/or carboxyl ligands is greater than or equal to 10 minutes;
  • the zinc oxide nanoparticles are dissolved to obtain a zinc oxide colloidal solution.
  • the zinc salt solution is a salt solution formed by dissolving the zinc salt in a solvent
  • the lye solution is a solution formed by an alkali capable of reacting with the zinc salt to generate zinc hydroxide.
  • the selection of zinc salt and solvent in the zinc salt solution, the alkali in the lye and its formation method, the selection of solvent, and the addition ratio of zinc salt and lye in the reaction system are as described in the first implementation above.
  • amine ligands and/or carboxyl ligands having 8-18 carbon atoms include, but are not limited to, octanoic acid, octylamine, dodecanoic acid, dodecylamine, oleic acid, and oleylamine.
  • amine ligands and/or carboxyl ligand having 8-18 carbon atoms after the amine ligand and/or carboxyl ligand having 8-18 carbon atoms is configured into a ligand solution, it is mixed and reacted with a zinc salt solution and a lye.
  • the solvent in the ligand solution choose a solvent with greater polarity, mainly considering the solubility of the reaction raw materials and products.
  • the solvent in the ligand solution is selected from at least one of methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and DMSO.
  • the amine ligand and/or carboxyl ligand having 8-18 carbon atoms is a ligand solution, and the concentration of the ligand solution is 0.2-0.4 mmol/L.
  • reaction temperature and time for the mixed reaction of the zinc salt solution and the alkali solution are as described in the first implementation manner above.
  • amine ligands and/or carboxyl ligands with carbon atoms of 8-18 are added during the reaction to prepare amino ligands and/or carboxyl groups with carbon atoms of 8-18 bound on the surface.
  • the addition amount of the amine ligands and/or carboxyl ligands with 8-18 carbon atoms satisfies: the amino ligands and/or carboxyl ligands with 8-18 carbon atoms and zinc salts
  • the molar ratio of the zinc salt in the solution is 1:1 to 10:1.
  • the added amine ligands and/or carboxyl ligands with a carbon number of 8-18 are bound to the surface in the resulting zinc oxide nanoparticles, thereby enabling the zinc oxide film to
  • the amine ligand and/or carboxyl ligand of -18 reduce the electron transport efficiency, thereby balancing the carrier injection balance in the quantum dot light-emitting diode, thereby helping to improve the external quantum efficiency of the device.
  • the addition amount of amine ligands and/or carboxyl ligands with carbon atoms of 8-18 is too small, there will be less long-chain ligands connected to the surface of zinc oxide, which is not easy to reduce the electron transfer efficiency and improve the EQE.
  • the electron mobility of the sample will decrease after the ligand exchange. Therefore, the electron mobility can be reduced and the EQE can be improved even if the ligand with a longer chain length is not added in a small amount.
  • the solubility of zinc oxide nanoparticles in polar solvents will be reduced, the film formation of the zinc oxide layer in the final device will be affected, and the device performance of the final device will be reduced;
  • the ligand chain length is short (8-12), the decrease of the electron mobility after ligand exchange is small, so the addition amount of the ligand with more chain length needs to be higher to achieve the purpose of improving EQE.
  • the number of carbon atoms of the amino ligand and/or the carboxyl ligand is 8-12, and the addition amount of the amino ligand and/or the carboxyl ligand satisfies: the amino ligand and/or the carboxyl ligand
  • the molar ratio of zinc salt to zinc salt solution is 4:1 ⁇ 10:1.
  • the number of carbon atoms of the amino ligand and/or the carboxyl ligand is 13-18, and the addition amount of the amino ligand and/or the carboxyl ligand satisfies: the amino ligand and/or the carboxyl ligand
  • the molar ratio of zinc salt to zinc salt solution is 1:1 ⁇ 5:1.
  • reaction time of continuing the reaction after adding the amine ligand and/or carboxyl ligand with a carbon number of 8-18 is greater than or equal to 10 minutes, so that the ligand and the hydroxyl groups on the surface of the generated zinc oxide nanoparticles are sufficient. exchange.
  • the mixture is stirred for 10 minutes to 2 hours, so that the exchange reaction can be fully carried out. In some embodiments, the stirring time is 30 minutes to 1 h.
  • a precipitant is added to the mixed solution after the reaction is completed, and the precipitate is collected.
  • the selection and addition amount of the precipitant are as described in the first implementation manner above.
  • the precipitation-treated mixed system is centrifuged to collect the precipitate.
  • the collected precipitate is washed with a reaction solvent to remove reactants that do not participate in the reaction.
  • Using the reaction solvent to clean the obtained zinc oxide nanoparticles can remove the excess zinc salt, alkali and other raw materials for preparing the zinc oxide nanoparticles, so as to improve the purity of the zinc oxide nanoparticles.
  • the reaction solvent is as above.
  • the reaction solvent is selected from at least one of water, organic alcohols, organic ethers, and sulfones.
  • reaction solvents have relatively high polarity, and can effectively remove raw material impurities such as zinc salts, alkalis and other residual impurities and intermediate impurities in the zinc oxide nanoparticles.
  • the reaction solvent is selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and DMSO.
  • the washed precipitate is dissolved to obtain a zinc oxide colloid solution.
  • an amine ligand and/or a carboxyl ligand having a carbon number of 8-18 is added after the zinc oxide colloidal solution is prepared.
  • the steps of preparing the zinc oxide colloidal solution by the solution method include:
  • the zinc oxide nanoparticles are dissolved to obtain a zinc oxide colloidal solution.
  • the zinc salt solution is a salt solution formed by dissolving the zinc salt in a solvent
  • the lye solution is a solution formed by an alkali capable of reacting with the zinc salt to generate zinc hydroxide.
  • the selection of zinc salt and solvent in the zinc salt solution, the alkali in the lye and its formation method, the selection of solvent, and the addition ratio of zinc salt and lye in the reaction system are as described in the first implementation above.
  • the amine ligand and/or carboxyl ligand having 8-18 carbon atoms, the choice of solvent in the ligand solution, and the concentration of the ligand solution are as described in the first implementation above.
  • reaction temperature and time for the mixed reaction of the zinc salt solution and the alkali solution are as described in the first implementation manner above.
  • the addition amount of the amine ligands and/or carboxyl ligands with 8-18 carbon atoms satisfies: the amino ligands and/or carboxyl ligands with 8-18 carbon atoms and zinc salts
  • the molar ratio of the zinc salt in the solution is 1:1 to 10:1.
  • the added amine ligands and/or carboxyl ligands with a carbon number of 8-18 are bound to the surface in the resulting zinc oxide nanoparticles, thereby enabling the zinc oxide film to
  • the amine ligand and/or carboxyl ligand of -18 reduce the electron transport efficiency, thereby balancing the carrier injection balance in the quantum dot light-emitting diode, thereby helping to improve the external quantum efficiency of the device.
  • the addition amount of amine ligands and/or carboxyl ligands with carbon atoms of 8-18 is too small, there will be less long-chain ligands connected to the surface of zinc oxide, which is not easy to reduce the electron transfer efficiency and improve the EQE.
  • the electron mobility of the sample will decrease after the ligand exchange. Therefore, the electron mobility can be reduced and the EQE can be improved even if the ligand with a longer chain length is not added in a small amount.
  • the solubility of zinc oxide nanoparticles in polar solvents will be reduced, the film formation of the zinc oxide layer in the final device will be affected, and the device performance of the final device will be reduced;
  • the ligand chain length is short (8-12), the decrease of the electron mobility after ligand exchange is small, so the addition amount of the ligand with more chain length needs to be higher to achieve the purpose of improving EQE.
  • the number of carbon atoms of the amino ligand and/or the carboxyl ligand is 8-12, and the addition amount of the amino ligand and/or the carboxyl ligand satisfies: the amino ligand and/or the carboxyl ligand
  • the molar ratio of zinc salt to zinc salt solution is 4:1 ⁇ 10:1.
  • the number of carbon atoms of the amino ligand and/or the carboxyl ligand is 13-18, and the addition amount of the amino ligand and/or the carboxyl ligand satisfies: the amino ligand and/or the carboxyl ligand
  • the molar ratio of zinc salt to zinc salt solution is 1:1 ⁇ 5:1.
  • reaction time of continuing the reaction after adding the amine ligand and/or carboxyl ligand with a carbon number of 8-18 is greater than or equal to 10 minutes, so that the ligand and the hydroxyl groups on the surface of the generated zinc oxide nanoparticles are sufficient. exchange.
  • the mixture is stirred for 10 minutes to 2 hours, so that the exchange reaction can be fully carried out. In some embodiments, the stirring time is 30 minutes to 1 h.
  • a precipitant is added to the mixed solution after the reaction is completed, and the precipitate is collected. Selection of the precipitant The selection and addition amount of the precipitant are as described in the first implementation manner above.
  • the precipitation-treated mixed system is centrifuged to collect the precipitate.
  • the collected precipitate is washed with a reaction solvent to remove reactants that do not participate in the reaction.
  • Using the reaction solvent to clean the obtained zinc oxide nanoparticles can remove the excess zinc salt, alkali and other raw materials for preparing the zinc oxide nanoparticles, so as to improve the purity of the zinc oxide nanoparticles.
  • the reaction solvent is as above.
  • the reaction solvent is selected from at least one of water, organic alcohols, organic ethers, and sulfones.
  • reaction solvents have relatively high polarity, and can effectively remove raw material impurities such as zinc salts, alkalis and other residual impurities and intermediate impurities in the zinc oxide nanoparticles.
  • the reaction solvent is selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and DMSO.
  • the washed precipitate is dissolved to obtain a zinc oxide colloid solution.
  • the steps of preparing the zinc oxide colloidal solution by the solution method include:
  • the product is collected and cleaned to obtain zinc oxide nanoparticles
  • the zinc salt solution is a salt solution formed by dissolving the zinc salt in a solvent
  • the lye solution is a solution formed by an alkali capable of reacting with the zinc salt to generate zinc hydroxide.
  • the selection of zinc salt and solvent in the zinc salt solution, the alkali in the lye and its formation method, the selection of solvent, and the addition ratio of zinc salt and lye in the reaction system are as described in the first implementation above.
  • reaction temperature and time for reacting the zinc salt solution are as described in the above-mentioned first implementation manner.
  • a precipitant is added to the mixed solution after the reaction is completed, and the precipitate is collected. Selection of the precipitant The selection and addition amount of the precipitant are as described in the first implementation manner above.
  • the precipitation-treated mixed system is centrifuged to collect the product.
  • the collected product is washed with a reaction solvent to remove reactants that do not participate in the reaction.
  • Using the reaction solvent to clean the obtained zinc oxide nanoparticles can remove raw materials such as redundant zinc salts, alkalis and the like for preparing the zinc oxide nanoparticles, so as to improve the purity of the zinc oxide nanoparticles.
  • the reaction solvent is as above.
  • the reaction solvent is selected from at least one of water, organic alcohols, organic ethers, and sulfones.
  • reaction solvents have relatively high polarity, and can effectively remove raw material impurities such as zinc salts, alkalis and other residual impurities and intermediate impurities in the zinc oxide nanoparticles.
  • the reaction solvent is selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and DMSO.
  • amine ligands and/or carboxyl ligands with a carbon number of 8-18 are added to react, and an amino group with a carbon number of 8-18 is bound on the surface of the zinc oxide.
  • amine ligands and/or carboxyl ligands having 8-18 carbon atoms include, but are not limited to, octanoic acid, octylamine, dodecanoic acid, dodecylamine, oleic acid, and oleylamine.
  • amine ligands and/or carboxyl ligand having 8-18 carbon atoms after the amine ligand and/or carboxyl ligand having 8-18 carbon atoms is configured into a ligand solution, it is mixed and reacted with a zinc salt solution and a lye.
  • the solvent in the ligand solution choose a solvent with greater polarity, mainly considering the solubility of the reaction raw materials and products.
  • the solvent in the ligand solution is selected from at least one of methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and DMSO.
  • the amine ligand and/or carboxyl ligand having 8-18 carbon atoms is a ligand solution, and the concentration of the ligand solution is 0.05-0.1 mmol/L.
  • the concentration is too low, the addition of amine ligands and/or carboxyl ligands with carbon atoms of 8-18 is too small, and it is difficult to play an effective ligand exchange effect; in this example, the zinc oxide finally obtained after cleaning Add the amino/carboxyl ligand solution to the colloid solution, and there is no subsequent cleaning and purification process. Therefore, when the concentration is too high, the amount of amino ligands and/or carboxyl ligands with carbon atoms of 8-18 is too high. , the remaining ligands will directly remain in the final ZnO electron transport layer film, and the excess ligands will affect the film-forming quality and properties of the ZnO electron transport layer.
  • the addition amount of the amine ligands and/or carboxyl ligands with 8-18 carbon atoms satisfies: the amino ligands and/or carboxyl ligands with 8-18 carbon atoms and zinc salts
  • the molar ratio of the zinc salt in the solution is 1:4 to 4:1.
  • the added amine ligands and/or carboxyl ligands with a carbon number of 8-18 bind to the surface in the resulting ZnO nanoparticles, reducing the electron mobility of the ZnO electron transport layer, thereby reducing the electron mobility of the ZnO electron transport layer.
  • the electron mobility of the sample will decrease after the ligand exchange. Therefore, the electron mobility can be reduced and the EQE can be improved even if the ligand with a longer chain length is not added in a small amount.
  • the solubility of zinc oxide nanoparticles in polar solvents will be reduced, the film formation of the zinc oxide layer in the final device will be affected, and the device performance of the final device will be reduced;
  • the ligand chain length is short (8-12), the decrease of the electron mobility after ligand exchange is small, so the addition amount of the ligand with more chain length needs to be higher to achieve the purpose of improving EQE.
  • the number of carbon atoms of the amino ligand and/or the carboxyl ligand is 8-12, and the addition amount of the amino ligand and/or the carboxyl ligand satisfies: the amino ligand and/or the carboxyl ligand
  • the molar ratio of zinc salt to zinc salt solution is 1:1 ⁇ 10:1.
  • the number of carbon atoms of the amino ligand and/or the carboxyl ligand is 13-18, and the addition amount of the amino ligand and/or the carboxyl ligand satisfies: the amino ligand and/or the carboxyl ligand
  • the molar ratio of zinc salt to zinc salt solution is 1:4 ⁇ 5:1.
  • reaction time of continuing the reaction after adding the amine ligand and/or carboxyl ligand with a carbon number of 8-18 is greater than or equal to 10 minutes, so that the ligand and the hydroxyl groups on the surface of the generated zinc oxide nanoparticles are sufficient. exchange.
  • the mixture is stirred for 10 minutes to 2 hours, so that the exchange reaction can be fully carried out. In some embodiments, the stirring time is 30 minutes to 1 h.
  • the above-mentioned zinc oxide colloid solution can be formed on the prefabricated device substrate by adopting, but not limited to, a spin coating method, a blade coating method, a printing method, a spray coating method, a roller coating method, an electrodeposition method, and the like. kind.
  • the solvent is removed by annealing to obtain a zinc oxide film with amine ligands and/or carboxyl ligands with 8-18 carbon atoms bound to the surface of the zinc oxide.
  • the quantum dot light-emitting diode is an upright quantum dot light-emitting diode
  • the prefabricated device substrate includes an anode substrate, and a quantum dot light-emitting layer combined on the anode substrate.
  • the prefabricated device substrate further includes a hole functional layer disposed between the anode substrate and the quantum dot light-emitting layer.
  • the hole functional layer includes at least one of a hole transport layer, a hole injection layer and an electron blocking layer.
  • the quantum dot light emitting diode is an inverted quantum dot light emitting diode
  • the prefabricated device substrate is a cathode substrate.
  • the prefabricated device substrate further includes an electron injection layer bonded to the cathode surface of the cathode substrate.
  • the first electron transport layer may alone function as the electron transport layer.
  • the electron transport layer includes two zinc oxide films or n thin film stack units consisting of two zinc oxide films, named as the first electron transport layer and the second electron transport layer, respectively layers, n is greater than or equal to 2. In some embodiments, n is an integer greater than or equal to 2 and less than or equal to 9.
  • at least the first electron transport layer is a zinc oxide film prepared by the above method and the surface of which is combined with amine ligands with 8-18 carbon atoms and/or carboxyl ligands
  • the situation of the second electron transport layer can refer to the above The situation in the second electron transport layer of a quantum dot light-emitting diode device.
  • the second electron transport layer is a zinc oxide film with surface hydroxyl groups less than or equal to 0.4, or the second electron transport layer is a metal-doped zinc oxide film.
  • the first electron transport layer may be disposed on the side adjacent to the quantum dot light-emitting layer, or may be disposed on the side adjacent to the cathode.
  • the second electron transport layer is disposed on the side adjacent to the quantum dot light-emitting layer or the metal-doped zinc oxide film is disposed on the side adjacent to the quantum dot light-emitting layer, so that a more flat zinc oxide film can be obtained.
  • the electron transport layer includes three zinc oxide films, named as the first electron transport layer, the second electron transport layer and the third electron transport layer, respectively.
  • the first electron transport layer is a zinc oxide film prepared by the above method and the surface of which is combined with amine ligands and/or carboxyl ligands with a carbon number of 8-18, the second electron transport layer and the third electron transport layer.
  • the electron transport layer includes the third electron transport layer.
  • the zinc oxide film with the surface hydroxyl amount greater than or equal to 0.6 can be formed by a zinc oxide colloidal solution with the surface hydroxyl amount greater than or equal to 0.6.
  • the zinc oxide film with the surface hydroxyl content of less than or equal to 0.4 can be formed by the zinc oxide colloidal solution with the surface hydroxyl content of less than or equal to 0.4.
  • the zinc salt and solvent type of the zinc salt solution the content of the zinc salt solution, the type and content of doping ions, the type and addition amount of alkaline solution, the reaction temperature and reaction time, the choice of precipitant and The amount of addition is carried out with reference to the above-mentioned step S11 in the embodiment of the present application.
  • the zinc salt solution containing doped metal ions can be obtained by dissolving the zinc salt and the selected metal salt in a solvent at room temperature in a certain proportion.
  • the addition amount of the alkali satisfies: the ratio of the product of the molar amount of the metal ion and the valence number to the molar amount of the hydroxide ion is 0.75:1 ⁇ 1.25 :1.
  • the examples of the present application provide a method for preparing a quantum dot light-emitting diode.
  • the quantum dot light-emitting diode includes an anode and a cathode arranged opposite to each other, and a quantum dot light-emitting layer arranged between the anode and the cathode is arranged on the The electron transport layer between the quantum dot light-emitting layer and the cathode, wherein the electron transport layer includes a first electron transport layer, and at least one surface of the first electron transport layer contains an amine ligand with a carbon number of 8-18 and / or carboxyl ligands;
  • the preparation method of the first electron transport layer includes:
  • an amine ligand and/or a carboxyl ligand solution with a carbon number of 8-18 is deposited on the surface of a zinc oxide prefabricated film to promote the amine ligand and/or
  • the carboxyl ligands and the hydroxyl ligands on the surface of the zinc oxide colloid perform ligand exchange, and then the amine ligands and/or carboxyl ligands with carbon atoms of 8-18 are coordinated on the surface of the zinc oxide colloid.
  • the ZnO nanoparticles in solution and after film formation are increased.
  • the distance between them thereby reducing the electron mobility of the electron transport layer, inhibiting the transport of electrons in the electron transport layer, and reducing the transport of electrons in the quantum dot light-emitting diode, thereby reducing the electrons injected into the quantum dot light-emitting layer, realizing quantum dots.
  • the injection of carriers in the dot light-emitting diode is balanced, and finally a quantum dot light-emitting diode with higher external quantum efficiency is obtained.
  • the composition of the quantum dot light-emitting diode is as in the first aspect above. In order to save space, it is not repeated here.
  • the zinc oxide prefabricated film can be prepared in various ways, for example, the zinc oxide prefabricated film is prepared by a solution method or a sol-gel method.
  • the prefabricated zinc oxide film is prepared by a solution method, including: mixing and reacting a zinc salt solution with an alkaline solution to prepare zinc oxide nanoparticles; dissolving the zinc oxide nanoparticles to obtain a zinc oxide colloidal solution; A zinc oxide colloid solution is formed on the prefabricated device substrate of the first electron transport layer, and the solvent is removed to prepare a zinc oxide prefabricated film.
  • the zinc oxide colloidal solution is prepared by a solution method, and the solution method can be one of alcoholysis method, hydrolysis method and the like.
  • the basic process of preparing zinc oxide by solution method is as follows: mixing zinc salt solution with lye, reacting to generate hydroxide intermediates such as zinc hydroxide; the hydroxide intermediate undergoes polycondensation reaction to gradually generate zinc oxide nanoparticles.
  • the selection basis and type of the zinc salt solution, the zinc salt in the zinc salt solution and the solvent, and the formation method of the zinc salt solution are as in the first embodiment above.
  • the selection basis and type of the lye, the alkali and the solvent in the lye, and the formation method of the lye are as in the first embodiment above.
  • the zinc salt solution is mixed with the lye, and the reaction is performed for 30 minutes to 4 hours, so as to prepare zinc oxide nanoparticles.
  • the method of mixing the zinc salt solution and the lye solution is as follows: dissolving the zinc salt at room temperature (5°C to 40°C) to obtain the zinc salt solution, dissolving or diluting the alkali at room temperature to obtain the lye solution; The temperature of the solution was adjusted to 0-70° C., and lye was added. In this case, the added base reacts with the zinc salt in the zinc salt solution to form zinc oxide nanoparticles, and good particle dispersibility can be obtained.
  • the reaction temperature of the zinc salt solution and the alkali solution is room temperature to 50° C.
  • the obtained zinc oxide ions have better particle dispersibility , which is beneficial to the film formation of zinc oxide colloidal solution.
  • the zinc salt solution under the condition of temperature of 0 ⁇ 30°C, the zinc salt solution is mixed with alkali solution, and qualified zinc oxide colloid solution can be easily generated; in some embodiments, the temperature is 30°C ⁇ 70°C Under the condition of °C, zinc oxide colloidal solution can also be generated, the quality of the obtained zinc oxide colloidal solution is not as good as the zinc oxide colloidal solution generated under the condition of 0-30 °C, and the reaction time is also shortened.
  • the zinc salt solution in the step of mixing the zinc salt solution with the lye solution, is mixed with the lye solution according to the molar ratio of hydroxide ions to zinc ions in the range of 1.5:1 to 2.5:1. , to ensure the formation of ZnO nanoparticles and reduce the formation of reaction by-products.
  • the zinc salt is significantly excessive, which makes it difficult for a large amount of zinc salt to generate zinc oxide nanoparticles; and when the molar ratio of hydroxide ion to zinc ion is greater than 2.5:1 , the lye is significantly excessive, and the excess hydroxide ion forms a stable complex with the zinc hydroxide intermediate, which is not easy to polycondensate to form zinc oxide nanoparticles.
  • the addition amounts of the zinc salt solution and the lye solution satisfy: the molar amount of hydroxide ions provided by the lye solution and the molar amount of zinc ions provided by the zinc salt The ratio of quantity is 1.7:1 ⁇ 1.9:1.
  • the reaction is carried out at a reaction temperature of 0-70° C. for 30 minutes to 4 hours to ensure the formation of zinc oxide nanoparticles and to control the particle size of the nanoparticles.
  • the reaction time is less than 30min, the reaction time is too low to obtain the cluster seeds of zinc oxide.
  • the crystalline state of the sample is incomplete and the crystal structure is poor.
  • it is used as an electron transport layer material, it will The conductivity of the electron transport layer is very poor; when the reaction time exceeds 4h, the long particle growth time makes the generated nanoparticles too large and the particle size is uneven, and the surface roughness of the zinc oxide colloid solution after film formation will be higher. high, which affects the transport properties of electrons.
  • the reaction is carried out at the reaction temperature for 1-2 hours.
  • the zinc salt solution is mixed with the lye, and the reaction is performed for 30 min to 4 h under stirring conditions, so as to promote the uniformity of the reaction and the resulting zinc oxide nanoparticles. Particle uniformity of the particles to produce zinc oxide nanoparticles of uniform size.
  • the zinc oxide colloidal solution can be obtained by dissolving the prepared zinc oxide nanoparticles.
  • the method for obtaining zinc oxide nanoparticles further includes: after the reaction is completed, adding a precipitant to the mixed solution after the reaction is completed, and collecting the precipitate.
  • the precipitant selects a solvent of opposite polarity to the final product zinc oxide nanoparticles, thereby precipitating the zinc oxide nanoparticles by reducing their solubility.
  • the precipitant selects a solvent with a weaker polarity, which is opposite to the polarity of the zinc oxide nanoparticles, which is favorable for the precipitation of the zinc oxide nanoparticles.
  • precipitating agents include, but are not limited to, ethyl acetate, acetone, n-hexane, n-heptane, and other low-polar long-chain alkanes.
  • the volume ratio of the precipitant to the mixed solution is 2:1 to 6:1
  • a white precipitate is generated in the mixed solution .
  • the volume ratio of the precipitant to the mixed solution is 3:1 to 5:1.
  • the precipitation-treated mixed system is centrifuged to collect the precipitate.
  • a reaction solvent is used to wash the collected precipitate to remove reactants that do not participate in the reaction.
  • Using the reaction solvent to clean the obtained zinc oxide nanoparticles can remove the excess zinc salt, alkali and other raw materials for preparing the zinc oxide nanoparticles, so as to improve the purity of the zinc oxide nanoparticles.
  • the reaction solvent is as above.
  • the reaction solvent is selected from at least one of water, organic alcohols, organic ethers, and sulfones.
  • the reaction solvent is selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and DMSO.
  • the first electron transport layer is a metal-doped zinc oxide film, and correspondingly, the zinc oxide in the first electron transport layer is metal-doped zinc oxide.
  • the zinc salt solution also contains Doping with metal ions.
  • the selection of the doping metal ions and the doping content are the same as the selection of the doping metal in the metal-doped zinc oxide film above.
  • the above zinc oxide colloidal solution can be formed on the prefabricated device substrate on which the first electron transport layer is to be prepared, and the solvent can be removed to obtain a zinc oxide prefabricated film.
  • the above-mentioned zinc oxide colloid solution can be formed on the prefabricated device substrate by adopting, but not limited to, a spin coating method, a blade coating method, a printing method, a spray coating method, a roller coating method, an electrodeposition method, and the like. kind.
  • the solvent is removed by annealing treatment to obtain a zinc oxide prefabricated film.
  • the zinc oxide prefabricated film is prepared by a sol-gel method (high temperature calcination method). Specifically, the zinc oxide precursor is directly spin-coated on the substrate on which the zinc oxide prefabricated film is to be prepared, and then heat treated at high temperature to make it into zinc oxide.
  • a sol-gel method high temperature calcination method
  • step S52 by depositing an amine ligand and/or carboxyl ligand solution with a carbon number of 8-18 on the zinc oxide prefabricated film, the amine ligand and/or carboxyl ligand and the surface of the zinc oxide colloid are promoted.
  • the hydroxyl ligands perform ligand exchange, and then the amino ligands and/or carboxyl ligands having 8-18 carbon atoms are coordinated on the surface of the zinc oxide colloid.
  • the coordination solution of amine ligands and/or carboxyl ligands with 8-18 carbon atoms refers to the coordination of amino ligands and/or carboxyl ligands with 8-18 carbon atoms
  • the resulting ligand solution is dissolved in a solvent.
  • amine ligands and/or carboxyl ligands having 8-18 carbon atoms include, but are not limited to, octanoic acid, octylamine, dodecanoic acid, dodecylamine, oleic acid, and oleylamine.
  • a more polar solvent is selected, mainly considering the solubility of the reaction starting materials and products.
  • the solvent for dissolving amine ligands and/or carboxyl ligands with a carbon number of 8-18 including but not limited to one of water, alcohols and other polar solvents , exemplarily, the solvent for dissolving amine ligands and/or carboxyl ligands with a carbon number of 8-18 is selected from water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol mono At least one of methyl ether and DMSO.
  • the concentration and addition amount of the amino ligand and/or carboxyl ligand solution having 8-18 carbon atoms is 0.05-0.1 mmol/L.
  • the concentration of the amine ligand and/or the carboxyl ligand with a carbon number of 8-18 is 0.05-0.1 mmol/L, and the carbon atom number is deposited on the surface of the zinc oxide prefabricated film
  • the addition amount of amino ligands and/or carboxyl ligands with 8-18 carbon atoms satisfies: per 5 mg of zinc oxide prefabricated films , and deposit 50 ⁇ L-1000 ⁇ L of amine ligand and/or carboxyl ligand solution with a carbon number of 8-18.
  • the electron mobility of the sample will decrease after the ligand exchange. Therefore, the electron mobility can be reduced and the EQE can be improved even if the ligand with a longer chain length is not added in a small amount.
  • the polarity of the ZnO nanoparticles will be changed, thereby affecting the wettability and film-forming property of the ZnO film, and finally reducing the device performance of the device;
  • the length is shorter (8-12)
  • the decrease of the electron mobility after ligand exchange is small, so the addition amount of the ligand with longer chain length needs to be higher to achieve the purpose of improving EQE.
  • the amine ligand and/or carboxyl group having 8-18 carbon atoms when the carbon atoms of the amine ligand and/or carboxyl ligand having 8-18 carbon atoms are 8-12, the amine ligand and/or carboxyl group having 8-18 carbon atoms
  • the addition amount of the ligand satisfies: per 5 mg of zinc oxide prefabricated film, deposit 100 ⁇ L-500 ⁇ L of amine ligand and/or carboxyl ligand solution with a carbon number of 8-12;
  • the carbon atoms of the body and/or carboxyl ligand are 13-18
  • the addition amount of the amine ligand and/or carboxyl ligand with a carbon number of 8-18 satisfies: per 5 mg of zinc oxide prefabricated film, the number of carbon atoms deposited 50 ⁇ L-300 ⁇ L of amino ligand and/or carboxyl ligand solution for 13-18.
  • the method for depositing the solution of amine ligands and/or carboxyl ligands with a carbon number of 8-18 on the surface of the zinc oxide prefabricated film can be a solution processing method, including but not limited to spin coating, scraping One of the coating method, printing method, spraying method, roller coating method, electrodeposition method, etc.
  • drying treatment is performed, and the amine ligand with a carbon number of 8-18 and/or a carboxyl ligand is dried by drying treatment. /or the ligands in the carboxyl ligand solution are fully exchanged with the hydroxyl groups on the surface of zinc oxide.
  • the drying temperature ranges from 10°C to 100°C, and the drying time ranges from 10 minutes to 2 hours.
  • the amine ligands and/or the electroligands in the carboxyl ligands with carbon atoms of 8-18 fully react with the hydroxyl groups on the surface of zinc oxide, thereby increasing the formation rate under the action of steric hindrance.
  • the distance between the ZnO nanoparticles after film formation reduces the electron mobility of the ZnO electron transport layer after film formation.
  • the drying temperature ranges from 10°C to 50°C, and the drying time ranges from 30 minutes to 2 hours.
  • the quantum dot light-emitting diode is an upright quantum dot light-emitting diode
  • the prefabricated device substrate includes an anode substrate, and a quantum dot light-emitting layer combined on the anode substrate.
  • the prefabricated device substrate further includes a hole functional layer disposed between the anode substrate and the quantum dot light-emitting layer.
  • the hole functional layer includes at least one of a hole transport layer, a hole injection layer and an electron blocking layer.
  • the quantum dot light emitting diode is an inverted quantum dot light emitting diode
  • the prefabricated device substrate is a cathode substrate.
  • the prefabricated device substrate further includes an electron injection layer bonded to the cathode surface of the cathode substrate.
  • the first electron transport layer may alone function as the electron transport layer.
  • the electron transport layer includes two zinc oxide films or n thin film stack units consisting of two zinc oxide films, named as the first electron transport layer and the second electron transport layer, respectively layers, n is greater than or equal to 2. In some embodiments, n is an integer greater than or equal to 2 and less than or equal to 9.
  • at least the first electron transport layer is a zinc oxide film prepared by the above method and the surface of which is combined with amine ligands with 8-18 carbon atoms and/or carboxyl ligands
  • the situation of the second electron transport layer can refer to the above The situation in the second electron transport layer of a quantum dot light-emitting diode device.
  • the second electron transport layer is a zinc oxide film with surface hydroxyl groups less than or equal to 0.4, or the second electron transport layer is a metal-doped zinc oxide film.
  • the first electron transport layer may be disposed on the side adjacent to the quantum dot light-emitting layer, or may be disposed on the side adjacent to the cathode.
  • the second electron transport layer is disposed on the side adjacent to the quantum dot light-emitting layer or the metal-doped zinc oxide film is disposed on the side adjacent to the quantum dot light-emitting layer, so that a more flat zinc oxide film can be obtained.
  • the electron transport layer includes three zinc oxide films, named as the first electron transport layer, the second electron transport layer and the third electron transport layer, respectively.
  • the first electron transport layer is a zinc oxide film prepared by the above method and the surface of which is combined with amine ligands and/or carboxyl ligands with a carbon number of 8-18, the second electron transport layer and the third electron transport layer.
  • the electron transport layer includes the third electron transport layer.
  • the method for preparing the zinc oxide thin film with the surface hydroxyl content of less than or equal to 0.4 includes:
  • the zinc salt solution is mixed and reacted with the alkaline solution to prepare zinc oxide nanoparticles; the zinc oxide nanoparticles are dissolved to obtain a zinc oxide colloidal solution; an acid solution is added to the zinc oxide colloidal solution to adjust the pH of the zinc oxide colloidal solution to 7-8, to obtain zinc oxide solution;
  • a zinc oxide solution is formed on a prefabricated device substrate on which a zinc oxide film with a surface hydroxyl content of less than or equal to 0.4 is to be prepared, and the solvent is removed to prepare a zinc oxide film with a surface hydroxyl content of less than or equal to 0.4.
  • the step of adding an acid solution to the zinc oxide colloidal solution and adjusting the pH of the zinc oxide colloidal solution to 7-8 adding an acid solution to the zinc oxide colloidal solution, so that the pH value of the obtained mixed solution is between 7.2 and 7.2 between 7.8.
  • the step of adding an acid solution to the zinc oxide colloidal solution and adjusting the pH of the zinc oxide colloidal solution to 7-8 adding an acid solution to the zinc oxide colloidal solution, so that the pH value of the obtained mixed solution is between 7.3 and 7.3. between 7.6.
  • the acid in the acid solution is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, formic acid, acetic acid, propionic acid, oxalic acid, and propylene.
  • the lye is selected from the lye formed by at least one of potassium hydroxide, sodium hydroxide, lithium hydroxide, TMAH, ammonia water, ethanolamine, and ethylenediamine.
  • the solvent in the zinc salt solution and the solvent in the lye solution are each independently selected from at least one of water, organic alcohol, organic ether, and sulfone.
  • the solvent in the acid solution is selected from at least one of water, methanol, ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl ether, and DMSO.
  • the zinc oxide film with a surface hydroxyl amount of less than or equal to 0.4 is a metal-doped zinc oxide film, and the zinc salt solution further contains doped metal ions.
  • the metal-doped zinc oxide film is as described above, and in order to save space, it will not be repeated here.
  • the device when the device is an upright quantum dot light emitting diode, after preparing the electron transport layer, it also includes evaporating a cathode on the electron transport layer to obtain a quantum dot light emitting diode. In some embodiments, prior to evaporating the cathode, it further includes preparing an electron injection layer on the electron transport layer.
  • the method further includes preparing two light emitting layers on the electron transport layer, and evaporating an anode on the quantum dot light emitting layer to obtain a quantum dot light emitting diode. In some embodiments, before evaporating the anode, the method further includes preparing a hole functional layer on the quantum dot light-emitting layer.
  • the method for forming the hole functional layer (including at least one of the hole injection layer, the hole transport layer and the electron blocking layer) and the quantum dot light-emitting layer preferably adopts a solution processing method, including but not limited to One of the spin coating method, blade coating method, printing method, spray method, roller coating method, electrodeposition method, etc.
  • the prepared quantum dot light-emitting diodes are packaged, and the package process can be packaged by a common machine or by manual packaging.
  • the oxygen content and the water content are both lower than 0.1 ppm to ensure the stability of the device.
  • the curing resin used for encapsulation is acrylic resin, acrylate resin or epoxy resin; resin curing adopts UV irradiation, heating or a combination of the two.
  • the method further includes performing ultraviolet irradiation, heating, positive and negative pressure, external application on the obtained quantum dot light emitting diode.
  • One or more treatments including an electric field and an external magnetic field are used to improve one or more aspects of the performance of the quantum dot light-emitting diode device, wherein the atmosphere during the application process can be air or an inert atmosphere.
  • X-ray photoelectron spectroscopy is a surface analysis method that uses X-rays of a certain energy to irradiate samples to stimulate the emission of inner electrons or valence electrons of atoms or molecules
  • the electrons excited by the photons are called photoelectrons, and the energy and quantity of the photoelectrons can be measured to obtain the composition of the object to be tested.
  • This technique can effectively distinguish the existence of three chemical states of oxygen in zinc oxide materials, namely lattice oxygen connected to metal atoms, oxygen defects formed during crystal growth, and hydroxyl oxygen.
  • XPS X-ray photoelectron spectroscopy
  • equipment model Thermo Fisher Scientific NEXSA
  • sample preparation method dilute the prepared zinc oxide solution to 30 mg/mL, spin-coat it on the pretreated glass sheet, Spin coating to form a film.
  • the calculation method of hydroxyl content the ratio of hydroxyl oxygen peak area to lattice oxygen peak area is the hydroxyl content ratio: As shown in Figure 11.
  • the external quantum efficiency parameters mainly include six parameters: voltage, current, brightness, external quantum dot efficiency, power efficiency and luminescence spectrum; a certain voltage output is performed on the device in the cassette to make the device conduct light and record the current in time, and pass the silicon light.
  • the diode collects the light source, analyzes the spectral data, and obtains the color coordinates.
  • the G( ⁇ ) human eye photopic vision function and the S( ⁇ ) normalized electroluminescence spectrum can be calculated, so the calculation method of the current efficiency ⁇ A for:
  • L is the brightness read by the silicon photodiode
  • JD is the device current density
  • I is the ratio of the device area (a) to the current (I) flowing through the device.
  • the 128-channel QLED life test system communicates through the PCI bus of the central processing computer, and controls the digital IO card of NI (National Instruments) to realize the chip selection of the number of channels and the output of digital signals, and the corresponding digital signals are converted into analog signals through the D/A chip. signal, complete the current output (I), and realize data acquisition through the data acquisition card.
  • the collection of brightness converts the optical signal into an electrical signal through the sensor, and uses the electrical signal to simulate the brightness change (L).
  • (A) Choose three to four different constant current densities, (such as 100mA cm ⁇ 2, 50mA cm ⁇ 2, 20mA cm ⁇ 2, 10mA cm ⁇ 2), and test the initial brightness under the corresponding conditions.
  • a quantum dot light emitting diode comprising an anode substrate and a cathode arranged oppositely, a quantum dot light emitting layer arranged between the anode and the cathode, a hole transport layer arranged between the anode and the quantum dot light emitting layer, The hole injection layer between the hole transport layers, and the electron transport layer between the quantum dot light-emitting layer and the cathode, wherein the anode is ITO (55nm), and the hole injection layer is PEDOT:PSS (50nm).
  • the hole transport layer is TFB (30nm)
  • the quantum dot light-emitting layer is red quantum dots Cd x Zn 1-x Se/ZnSe (40nm)
  • the electron transport layer is the ZnO material (50nm) prepared by the following method, the cathode For Ag electrode (100nm).
  • the preparation method of the above quantum dot light-emitting diode comprising:
  • a hole injection layer, a hole transport layer and a quantum dot light-emitting layer are sequentially prepared on the anode substrate;
  • the preparation method of the electron transport layer is:
  • Step 2 A zinc oxide colloid solution is formed on the quantum dot light-emitting layer, and the solvent is removed to obtain a zinc oxide film with a surface hydroxyl content of 0.85, namely an electron transport layer, and the thickness of the zinc oxide film is 50 nm.
  • the hydroxyl groups in the zinc oxide for forming the electron transport layer were detected by X-ray photoelectron spectroscopy (XPS), and the hydroxyl group content of the electron transport layer was determined to be 0.85.
  • XPS X-ray photoelectron spectroscopy
  • Example 2 The difference from Example 1 is that commercially available ordinary zinc oxide nanoparticles are used as the electron transport layer material.
  • the hydroxyl groups in the zinc oxide for forming the electron transport layer were detected by X-ray photoelectron spectroscopy (XPS), and the hydroxyl group content of the electron transport layer was determined to be 0.5.
  • XPS X-ray photoelectron spectroscopy
  • Example 14 The device life test results of the quantum dot light-emitting diodes provided in Example 1 and Comparative Example 1 are shown in FIG. 14 .
  • a quantum dot light emitting diode comprising an anode substrate and a cathode arranged oppositely, a quantum dot light emitting layer arranged between the anode and the cathode, a hole transport layer arranged between the anode and the quantum dot light emitting layer, The hole injection layer between the hole transport layers, and the electron transport layer between the quantum dot light-emitting layer and the cathode, wherein the anode is ITO (55nm), and the hole injection layer is PEDOT:PSS (50nm).
  • the hole transport layer is TFB (30nm)
  • the quantum dot light-emitting layer is red quantum dots Cd x Zn 1-x Se/ZnSe (40nm)
  • the electron transport layer is the ZnO material obtained by the following method
  • the cathode is an Ag electrode (100 nm).
  • the preparation method of the above quantum dot light-emitting diode comprising:
  • a hole injection layer, a hole transport layer and a quantum dot light-emitting layer are sequentially prepared on the anode substrate;
  • the preparation method of the electron transport layer is:
  • the first zinc oxide film with 0.85 is the first electron transport layer; the second zinc oxide colloid solution is formed on the first zinc oxide film, the solvent is removed, and the second zinc oxide film with the surface hydroxyl amount of 0.25 is obtained, namely the second electron transport layer Floor.
  • the thickness of the first zinc oxide layer is 60 nm, and the thickness of the second zinc oxide layer is 40 nm.
  • X-ray photoelectron spectroscopy was used to detect the hydroxyl groups in the zinc oxide prepared for the first electron transport layer and the second electron transport layer, and the hydroxyl group content of the first electron transport layer was determined to be 0.85, and the The content is 0.25.
  • the device EQE test results of the quantum dot light-emitting diodes provided in Example 2 and Comparative Example 1 are shown in FIG. 15 , and the life test results are shown in FIG. 16 .
  • a quantum dot light emitting diode comprising an anode substrate and a cathode arranged oppositely, a quantum dot light emitting layer arranged between the anode and the cathode, a hole transport layer arranged between the anode and the quantum dot light emitting layer, The hole injection layer between the hole transport layers, and the electron transport layer between the quantum dot light-emitting layer and the cathode, wherein the anode is ITO (55nm), and the hole injection layer is PEDOT:PSS (50nm).
  • the hole transport layer is TFB (30nm)
  • the quantum dot light-emitting layer is red quantum dots CdxZn1-xSe/ZnSe (40nm)
  • the electron transport layer is the ZnO material obtained by the following method
  • the cathode is an Ag electrode (100nm).
  • the preparation method of the above quantum dot light-emitting diode comprising:
  • a hole injection layer, a hole transport layer and a quantum dot light-emitting layer are sequentially prepared on the anode substrate;
  • the thickness of the first zinc oxide layer is 30 nm
  • the thickness of the second zinc oxide layer is 60 nm
  • the thickness of the third zinc oxide layer is 30 nm.
  • the hydroxyl groups in the prepared first electron transport layer, second electron transport layer and third electron transport layer were detected by X-ray photoelectron spectroscopy (XPS).
  • XPS X-ray photoelectron spectroscopy
  • the device EQE test results of the quantum dot light-emitting diodes provided in Example 3 and Comparative Example 1 are shown in FIG. 17 , and the life test results are shown in FIG. 18 .
  • the test of quantum dot light-emitting diode device life is different from the characterization of quantum dot light-emitting diode device efficiency, and the time of device efficiency test is usually short, so it characterizes the initial transient state of QLED device operation; while the device life is characterized by It is the ability to maintain the efficiency of the device after the device continues to work and enters a stable state, that is, the balance of carrier injection in the device after entering a stable working state.
  • a quantum dot light emitting diode comprising an anode substrate and a cathode arranged oppositely, a quantum dot light emitting layer arranged between the anode and the cathode, a hole transport layer arranged between the anode and the quantum dot light emitting layer, The hole injection layer between the hole transport layers, and the electron transport layer between the quantum dot light-emitting layer and the cathode, wherein the anode is ITO (55nm), and the hole injection layer is PEDOT:PSS (50nm).
  • the hole transport layer is TFB (30nm)
  • the quantum dot light-emitting layer is red quantum dots Cd x Zn 1-x Se/ZnSe (40nm)
  • the electron transport layer is the ZnO material (50nm) prepared by the following method, the cathode For Ag electrode (100nm).
  • the preparation method of the above quantum dot light-emitting diode comprising:
  • a hole injection layer, a hole transport layer and a quantum dot light-emitting layer are sequentially prepared on the anode substrate;
  • the preparation method of the electron transport layer is:
  • (B) Adjust the temperature of the zinc salt solution to 40°C, and add the alkali droplets into the zinc salt solution according to the molar ratio of hydroxide ion to zinc ion of 1.75:1, and then add oleylamine to mix (0.4mol /L), wherein the addition of the oleylamine ligand satisfies: the mol ratio of the oleylamine ligand and the zinc salt in the zinc salt solution is 2:1, and the mixed solution is continuously stirred under the condition that the reaction temperature remains at 40°C, Reaction 120min;
  • Example 4 The difference from Example 4 is that commercially available common zinc oxide nanoparticles are used as the electron transport layer material.
  • the device EQE results of the quantum dot light-emitting diodes provided in Example 4 and Comparative Example 2 are shown in FIG. 19 .
  • a quantum dot light emitting diode comprising an anode substrate and a cathode arranged oppositely, a quantum dot light emitting layer arranged between the anode and the cathode, a hole transport layer arranged between the anode and the quantum dot light emitting layer, The hole injection layer between the hole transport layers, and the electron transport layer between the quantum dot light-emitting layer and the cathode, wherein the anode is ITO (55nm), and the hole injection layer is PEDOT:PSS (50nm).
  • the hole transport layer is TFB (30nm)
  • the quantum dot light-emitting layer is red quantum dots Cd x Zn 1-x Se/ZnSe (40nm)
  • the electron transport layer is the ZnO material obtained by the following method
  • the cathode is an Ag electrode (100 nm).
  • the preparation method of the above quantum dot light-emitting diode comprising:
  • a hole injection layer, a hole transport layer and a quantum dot light-emitting layer are sequentially prepared on the anode substrate;
  • the preparation method of the electron transport layer is:
  • Example 5 The device EQE test results of the quantum dot light-emitting diodes provided in Example 5 and Comparative Example 2 are shown in FIG. 20 .
  • a quantum dot light emitting diode comprising an anode substrate and a cathode arranged oppositely, a quantum dot light emitting layer arranged between the anode and the cathode, a hole transport layer arranged between the anode and the quantum dot light emitting layer, The hole injection layer between the hole transport layers, and the electron transport layer between the quantum dot light-emitting layer and the cathode, wherein the anode is ITO (55nm), and the hole injection layer is PEDOT:PSS (50nm).
  • the hole transport layer is TFB (30nm)
  • the quantum dot light-emitting layer is red quantum dots CdxZn1-xSe/ZnSe (40nm)
  • the electron transport layer is the ZnO material obtained by the following method
  • the cathode is an Ag electrode (100nm).
  • the preparation method of the above quantum dot light-emitting diode comprising:
  • a hole injection layer, a hole transport layer and a quantum dot light-emitting layer are sequentially prepared on the anode substrate;
  • the preparation method of the electron transport layer is:
  • the deposition amount and the weight of the underlying zinc oxide prefabricated film satisfy: every 5 mg of zinc oxide prefabricated film is treated with 40 ⁇ L of oleyl amine solution, reacted at a temperature of 120 ° C for 20 min, and the solvent is removed to obtain zinc oxide with a thickness of 60 nm.
  • the thin film is the electron transport layer.
  • the device EQE test results of the quantum dot light-emitting diodes provided in Example 6 and Comparative Example 2 are shown in FIG. 21 .
  • a quantum dot light emitting diode comprising an anode substrate and a cathode arranged oppositely, a quantum dot light emitting layer arranged between the anode and the cathode, a hole transport layer arranged between the anode and the quantum dot light emitting layer, The hole injection layer between the hole transport layers, and the electron transport layer between the quantum dot light-emitting layer and the cathode, wherein the anode is ITO (55nm), and the hole injection layer is PEDOT:PSS (50nm).
  • the hole transport layer is TFB (30nm)
  • the quantum dot light-emitting layer is red quantum dots Cd x Zn 1- xSe/ZnSe (40nm)
  • the electron transport layer is the ZnO material obtained by the following method
  • the cathode is an Ag electrode ( 100nm).
  • the preparation method of the above quantum dot light-emitting diode comprising:
  • a hole injection layer, a hole transport layer and a quantum dot light-emitting layer are sequentially prepared on the anode substrate;
  • Example 7 The device EQE test results of the quantum dot light-emitting diodes provided in Example 7 and Comparative Example 2 are shown in FIG. 22 .
  • the EQE of the quantum dot light-emitting diode devices provided in the above Examples 4-7 and Comparative Example 2 was tested by using the JVL (Current Density-Voltage-Brightness) device external quantum efficiency test method, specifically as described above.
  • the test of quantum dot light-emitting diode device life is different from the characterization of quantum dot light-emitting diode device efficiency, and the time of device efficiency test is usually short, so it characterizes the initial transient state of QLED device operation; while the device life is characterized by It is the ability to maintain the efficiency of the device after the device continues to work and enters a stable state, that is, the balance of carrier injection in the device after entering a stable working state.

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Abstract

本申请公开了一种量子点发光二极管及其制备方法。量子点发光二极管包括相对设置的阳极和阴极，设置在阳极和阴极之间的量子点发光层，设置在量子点发光层和阴极之间的电子传输层，其中，电子传输层包括第一电子传输层，且第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；或所述电子传输层含有氧化锌，且至少部分所述氧化锌的表面含有碳原子数为8-18的胺基配体和/或羧基配体。本申请提供的量子点发光二极管，有效提升了量子点发光二极管器件的外量子效率。

Description

量子点发光二极管及其制备方法
本申请要求于2020年12月31日在中国专利局提交的、申请号为202011636998.6、发明名称为“量子点发光二极管的制备方法”的中国专利申请，2020年12月31日在中国专利局提交的、申请号为202011640060.1、发明名称为“量子点发光二极管及其制备方法”的中国专利申请，2020年12月31日在中国专利局提交的、申请号为202011639878.1、发明名称为“量子点发光二极管及其制备方法”的中国专利申请，2020年12月31日在中国专利局提交的、申请号为202011640040.4、发明名称为“量子点发光二极管的制备方法”的中国专利申请、2020年12月31日在中国专利局提交的、申请号为202011640396.8、发明名称为“量子点发光二极管的制备方法”的中国专利申请，以及2020年12月31日在中国专利局提交的、申请号为202011637282.8、发明名称为“量子点发光二极管的制备方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及显示技术领域，尤其涉及一种量子点发光二极管及其制备方法。
背景技术
量子点(quantum dot，QD)是一类由少量原子构成的纳米材料，其半径通常小于或接近于激子波尔半径，表现出显著的量子限域效应，具有独特的光学性能。近来，随着显示技术的不断发展，以量子点材料作为发光层的量子点发光二极管(Quantum Dot Light Emitting Diode，QLED)越来越受到人们的关注。量子点发光二极管具有发光效率高、发光颜色可控、色纯度高、器件稳定性好、可用于柔性用途等特点，在显示技术、固态照明等领域具有了巨大的应用前景。
QLED主要包括阴极、阳极和量子点发光层。为了改善器件性能，在此基础上，QLED还会引入空穴传输注入层、空穴传输层、电子传输层、电子注入层中的一层或多层作为功能层。氧化锌作为QLED中普遍采用的电子传输层材料，其与阴极和量子点发光层之间具有良好的能级匹配关系，显著降低了电子从阴极到量子点发光层的注入势垒，并且其较深的价带能级又可以起到有效阻挡空穴的功能。此外，氧化锌材料还具有优良的电子传输能力，其电子迁移率高达10 -3cm 2/V·S。这些特性都使氧化锌材料成为了量子点发光二极管器件中电子传输层的首先材料，显著提升了器件的稳定性和发光效率。
由于QLED显示技术与有机发光二极管(OrganicLight-Emitting Diode，OLED)显示技术在发光原理上具有相似性，因此，对于QLED器件中器件物理的解释、功能层材料能级的选择和搭配原则等，目前也均是遵循OLED中的已有理论体系。例如，在OLED器件中为了获得更高的器件性能，需要对器件两侧空穴和电子的载流子注入进行精细的调控，以实现在器件发光层中载流子的注入平衡。将上述OLED器件经典物理结论应用到QLED器件体系中时，由于考虑到氧化锌层的电子迁移率往往是要高于空穴传输层的空穴迁移率，为了在QLED器件中实现较好的载流子注入平衡，需要通过在量子点发光层和氧化锌层之间插入电子阻挡层等手段降低氧化锌层电子迁移率。当以上手段运用于QLED器件时，QLED器件性能确实得到了显著的提升，尤其是QLED器件效率，通过该方法实现了QLED器件20％以上的外量子效率，接近理论数值的上限。
但是，利用插入电子阻挡层等改变器件结构的方法来实现改善载流子注入平衡也存在着一定的局限性。这种方法一方面在实际器件制备中较难实现，它对于电子阻挡层有着严格的厚度要求，过厚或者过薄都难以起到有效的作用，甚至会降低QLED的器件性能，因此在实际操作中较难控制。此外，改变器件结构(增加电子阻挡层)的方法也会增加器件的制备成本，在将来的QLED器件量产时增加成本负担。因此，需要找寻更加有效成本更低的方法来降低氧化锌层的电子迁移率，进而实现QLED器件的载流子注入平衡，提高量子点发光二极管的外量子效率。
技术问题
本申请实施例的目的之一在于：提供一种量子点发光二极管及其制备方法。
技术解决方案
本申请实施例采用的技术方案是：
第一方面，提供一种量子点发光二极管，包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层；
其中，所述电子传输层包括第一电子传输层，且所述第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；或
所述电子传输层含有氧化锌，且至少部分所述氧化锌的表面含有碳原子数为8-18的胺基配体和/或羧基配体。
在一些实施例中，所述电子传输层为所述第一电子传输层，且所述第一电子传输层中的氧化锌为掺杂金属或未掺杂金属的氧化锌。
在一些实施例中，当所述电子传输层含有氧化锌时，所述电子传输层包括含有氧化锌的第一电子传输层，且形成所述第一电子传输层的氧化锌表面含有碳原子数为8-18的胺基配体和/或羧基配体。
在一些实施例中，所述电子传输层为所述第一电子传输层，且形成所述第一电子传输层的氧化锌为未掺杂氧化锌或金属掺杂氧化锌。
在一些实施例中，所述电子传输层还包括第二电子传输层，所述第二电子传输层设置在所述第一电子传输层靠近所述阴极或所述量子点发光层的一侧表面，且所述第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜或金属掺杂氧化锌。
在一些实施例中，所述电子传输层由所述第一电子传输层和所述第二电子传输层组成，且所述第二电子传输层较所述第一电子传输层更靠近所述量子点发光层。
在一些实施例中，所述电子传输层包括n个由第一电子传输层和所述第二电子传输层组成的薄膜叠层单元，其中，n大于或等于2。
在一些实施例中，所述电子传输层还包括第三电子传输层。
在一些实施例中，所述第三电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜。
在一些实施例中，所述第三电子传输层设置在所述第二电子传输层背离所述第一电子传输层的一侧表面，且所述第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜。
在一些实施例中，所述第三电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜。
在一些实施例中，所述第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜，且所述第三电子传输层设置在所述第一电子传输层背离所述第二电子传输层的一侧表面；或
所述第二电子传输层为金属掺杂氧化锌薄膜，且所述第三电子传输层设置在所述第二电子传输层和所述第一电子传输层之间。
在一些实施例中，所述第三电子传输层为金属掺杂氧化锌薄膜。
在一些实施例中，所述第三电子传输层设置在所述第二电子传输层背离所述第一电子传输层的一侧表面。
在一些实施例中，所述第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜。
在一些实施例中，所述第三电子传输层选自表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜，且所述第二电子传输层结合在所述第一电子传输层的一侧表面，所述第三电子传输层结合在所述第二电子传输层背离所述第一电子传输层的一侧表面。
在一些实施例中，所述碳原子数为8-18的胺基配体和/或羧基配体选自辛酸、辛胺、十二酸、十二胺、油酸、油胺中的至少一种。
在一些实施例中，所述表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜中，所述碳原子数为8-18的胺基配体和/或羧基配体与氧化锌的摩尔比为1:4～10:1。
在一些实施例中，所述表面含有碳原子数为8-18的胺基配体和/或羧基配体选自碳原子数为8-12的胺基配体和/或羧基配体，所述碳原子数为8-12的胺基配体和/或羧基配体与氧化锌的摩尔比为1:1～10:1；或
所述表面含有碳原子数为8-18的胺基配体和/或羧基配体选自碳原子数为13-18的胺基配体和/或羧 基配体，所述碳原子数为13-18的胺基配体和/或羧基配体与氧化锌的摩尔比为1:4～5:1。
在一些实施例中，所述电子传输层的厚度为10～100nm。
在一些实施例中，所述表面羟基量大于或等于0.6的氧化锌薄膜的厚度为10-30nm。
在一些实施例中，所述第一电子传输层的厚度为10-80nm。
在一些实施例中，所述表面羟基量小于或等于0.4的氧化锌薄膜的厚度为20-60nm。
在一些实施例中，所述金属掺杂氧化锌薄膜的厚度为10-30nm。
在一些实施例中，所述量子点发光层中的量子点选自单核量子点或核壳结构量子点，且所述量子点的核和壳化合物各自独立地选自CdS、CdSe、CdTe、ZnO、ZnS、ZnSe、ZnTe、GaAs、GaP、GaSb、HgS、HgSe、HgTe、InAs、InP、InSb、AlAs、AlP、CuInS、CuInSe、以及上述物质形成的核壳结构量子点或合金结构量子点中的至少一种；和/或
在一些实施例中，所述阳极的材料包括氧化锌、氧化铟、氧化锡、氧化铟锡、氧化铟锌、氟掺杂的氧化锡中的至少一种。
在一些实施例中，所述阴极的材料为Ag、Al、Au、Mg、Ca、Yb、Ba或者它们的合金。
在一些实施例中，所述量子点发光二极管还包括设置在所述阳极和所属量子点发光层中的空穴功能层，且所述空穴功能层至少包括空穴注入层、空穴传输层中的至少一种。
在一些实施例中，所述空穴注入层的材料选自聚(亚乙基二氧噻吩):聚苯乙烯磺酸盐(PEDOT:PSS)、HTL-1、HTL-2中的至少一种。
在一些实施例中，所述空穴传输层的材料选自4,4'-N,N'-二咔唑基-联苯、聚[(9,9'-二辛基芴-2,7-二基)-co-(4,4'-(N-(4-仲丁基苯基)二苯胺))]、聚(4-丁基苯基-二苯基胺)、4,4',4'-三(N-咔唑基)-三苯胺、聚(N-乙烯基咔唑)及其衍生物中的至少一种。
在一些实施例中，所述空穴注入层的材料选自聚(亚乙基二氧噻吩):聚苯乙烯磺酸盐(PEDOT:PSS)、HTL-1、HTL-2中的至少一种；所述空穴传输层的材料选自4,4'-N,N'-二咔唑基-联苯、聚[(9,9'-二辛基芴-2,7-二基)-co-(4,4'-(N-(4-仲丁基苯基)二苯胺))]、聚(4-丁基苯基-二苯基胺)、4,4',4'-三(N-咔唑基)-三苯胺、聚(N-乙烯基咔唑)及其衍生物中的至少一种。
在一些实施例中，所述金属掺杂氧化锌薄膜中的掺杂金属选自Mg 2+、Mn 2+中的至少一种；或所述金属掺杂氧化锌薄膜中的掺杂金属选自Al 3+、Y 3+、La 3+、Li +、Gd 3+、Zr 4+、Ce 4+中的至少一种。
在一些实施例中，所述掺杂金属的掺杂含量如下：
当所述掺杂金属为Mg 2+时，所述金属掺杂氧化锌薄膜中Mg 2+的掺杂摩尔浓度为0.1％～35％；
当所述掺杂金属为Mn 2+时，所述金属掺杂氧化锌薄膜中Mn 2+的掺杂摩尔浓度为0.1％～30％；
当所述掺杂金属为Al 3+时，所述金属掺杂氧化锌薄膜中Al 3+的掺杂摩尔浓度为0.1％～15％；
当所述掺杂金属为Y 3+时，所述金属掺杂氧化锌薄膜中Y 3+的掺杂摩尔浓度为0.1％～10％；
当所述掺杂金属为La 3+时，所述金属掺杂氧化锌薄膜中La 3+的掺杂摩尔浓度为0.1％～7％；
当所述掺杂金属为Li +时，所述金属掺杂氧化锌薄膜中Li +的掺杂摩尔浓度为0.1％～45％；
当所述掺杂金属为Gd 3+时，所述金属掺杂氧化锌薄膜中Gd 3+的掺杂摩尔浓度为0.01％～8％；
当所述掺杂金属为Zr 4+时，所述金属掺杂氧化锌薄膜中Zr 4+的掺杂摩尔浓度为0.1％～45％；
当所述掺杂金属为Ce 4+时，所述金属掺杂氧化锌薄膜中Ce 4+的掺杂摩尔浓度为0.1％～10％。
第一方面，提供几种量子点发光二极管的制备方法。
第一种量子点发光二极管的制备方法，所述量子点发光二极管包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层，其中，所述电子传输层包括第一电子传输层，且所述第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；
所述表面羟基量大于或等于0.6的氧化锌薄膜的制备方法，包括：
将锌盐溶液与第一碱液混合反应，反应结束后向混合溶液中加入沉淀剂，收集沉淀物；采用反应溶剂对所述沉淀物进行清洗处理两次或两次以下后，将得到的白色沉淀物溶解，得到氧化锌胶体溶液；
在待制备所述表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上形成所述氧化锌胶体溶 液，去除溶剂，制得表面羟基量大于或等于0.6的氧化锌薄膜。
在一些实施例中，所述第一碱液中的碱选自K b＞10 -1的碱，所述清洗处理的次数小于或等于2次；
所述第一碱液中的碱选自K b＜10 -1的碱，所述清洗处理的次数小于或等于1次。
在一些实施例中，所述K b＞10 -1的碱选自氢氧化钾、氢氧化钠、氢氧化锂中的至少一种，所述K b＜10 -1的碱选自TMAH、氨水、乙醇胺、乙二胺中的至少一种。
在一些实施例中，所述反应溶剂选自水、有机醇、有机醚、砜中的至少一种。
在一些实施例中，所述反应溶剂选自水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。
在一些实施例中，所述锌盐溶液与第一碱液混合的步骤中，按照氢氧根离子与锌离子的摩尔比为1.5:1～2.5:1的比例，将所述锌盐溶液与所述第一碱液混合处理。
在一些实施例中，所述表面羟基量大于或等于0.6的氧化锌薄膜为金属掺杂氧化锌薄膜，且所述锌盐溶液中还含有掺杂金属离子。
在一些实施例中，所述掺杂金属离子选自Mg 2+、Mn 2+中的至少一种；或所述掺杂金属离子选自Al 3+、Y 3+、La 3+、Li +、Gd 3+、Zr 4+、Ce 4+中的至少一种。
在一些实施例中，所述掺杂金属离子的掺杂浓度如下：
当所述掺杂金属离子为Mg 2+时，所述锌盐溶液中Mg 2+摩尔含量占金属离子总摩尔量的0.1％～35％；
当所述掺杂金属离子为Mn 2+时，所述锌盐溶液中Mn 2+摩尔含量占金属离子总摩尔量的0.1％～30％；
当所述掺杂金属离子为Al 3+时，所述锌盐溶液中Al 3+摩尔含量占金属离子总摩尔量的0.1％～15％；
当所述掺杂金属离子为Y 3+时，所述锌盐溶液中Y 3+摩尔含量占金属离子总摩尔量的0.1％～10％；
当所述掺杂金属离子为La 3+时，所述锌盐溶液中La 3+摩尔含量占金属离子总摩尔量的0.1％～7％；
当所述掺杂金属离子为Li +时，所述锌盐溶液中Li +摩尔含量占金属离子总摩尔量的0.1％～45％；
当所述掺杂金属离子为Gd 3+时，所述锌盐溶液中Gd 3+摩尔含量占金属离子总摩尔量的0.01％～8％；
当所述掺杂金属离子为Zr 4+时，所述锌盐溶液中Zr 4+摩尔含量占金属离子总摩尔量的0.1％～45％；
当所述掺杂金属离子为Ce 4+时，所述锌盐溶液中Ce 4+摩尔含量占金属离子总摩尔量的0.1％～10％。
在一些实施例中，所述锌盐溶液与第一碱液混合的步骤中，所述锌盐溶液与所述第一碱液的添加量满足：金属离子的摩尔量与化合价数的乘积与氢氧根离子的摩尔量之比为0.75：1～1.25:1。
第二种量子点发光二极管的制备方法，所述量子点发光二极管包括所述量子点发光二极管包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层，其中，所述电子传输层包括第一电子传输层，且形成所述第一电子传输层的氧化锌表面含有碳原子数为8-18的胺基配体和/或羧基配体；
所述第一电子传输层的制备方法为：
采用锌盐溶液、碱液和碳原子数为8-18的胺基配体和/或羧基配体作为原料，通过溶液法制备氧化锌胶体溶液；其中，所述氧化锌溶液中的氧化锌表面结合有碳原子数为8-18的胺基配体和/或羧基配体；
在待制备所述第一电子传输层的预制器件基板上形成氧化锌胶体溶液，去除溶剂，制得第一电子传输层。
在一些实施例中，所述通过溶液法制备氧化锌胶体溶液的步骤，包括：
将所述锌盐溶液、所述碱液和所述碳原子数为8-18的胺基配体和/或羧基配体混合反应，制备表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒；
将所述氧化锌纳米颗粒溶解，得到氧化锌胶体溶液。
在一些实施例中，所述通过溶液法制备氧化锌胶体溶液的步骤，包括：
将所述锌盐溶液与所述碱液混合反应，在反应过程中加入所述碳原子数为8-18的胺基配体和/或羧基配体，制备表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒；其中，加入所述碳原子数为8-18的胺基配体和/或羧基配体后的反应时间大于或等于10分钟；
将所述氧化锌纳米颗粒溶解，得到氧化锌胶体溶液。
在一些实施例中，所述通过溶液法制备氧化锌胶体溶液的步骤，包括：
将锌盐溶液与碱液混合反应制得氧化锌纳米颗粒后，加入所述碳原子数为8-18的胺基配体和/或羧基配体，继续反应，制备制备表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒；
将所述氧化锌纳米颗粒溶解，得到氧化锌胶体溶液。
在一些实施例中，所述通过溶液法制备氧化锌胶体溶液的步骤，包括：
将锌盐溶液与碱液混合反应，收集产物清洗处理，得到氧化锌纳米颗粒；
将所述氧化锌纳米颗粒溶解后，加入碳原子数为8-18的胺基配体和/或羧基配体反应，在氧化锌表面结合碳原子数为8-18的胺基配体和/或羧基配体，得到氧化锌胶体溶液。
在一些实施例中，加入碳原子数为8-18的胺基配体和/或羧基配体后，反应10分钟-2小时。
在一些实施例中，所述碳原子数为8-18的胺基配体和/或羧基配体为配体溶液，且所述配体溶液的浓度为0.2-0.4mmol/L。
在一些实施例中，所述碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：所述碳原子数为8-18的胺基配体和/或羧基配体与所述锌盐溶液中的锌盐的摩尔比为1:1～10:1。
在一些实施例中，所述胺基配体和/或羧基配体的碳原子数为8-12，且所述胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与所述锌盐溶液中的锌盐的摩尔比为4:1～10:1；
所述胺基配体和/或羧基配体的碳原子数为13-18，且所述胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与所述锌盐溶液中的锌盐的摩尔比为1:1～5:1。
在一些实施例中，所述碳原子数为8-18的胺基配体和/或羧基配体为配体溶液，且所述配体溶液的浓度为0.05-0.1mmol/L。
在一些实施例中，所述碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：所述碳原子数为8-18的胺基配体和/或羧基配体与所述锌盐溶液中的锌盐的摩尔比为1:4～4:1。
在一些实施例中，所述胺基配体和/或羧基配体的碳原子数为8-12，且所述胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与所述锌盐溶液中的锌盐的摩尔比为1:1～10:1；
所述胺基配体和/或羧基配体的碳原子数为13-18，且所述胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与所述锌盐溶液中的锌盐的摩尔比为1:4～5:1。
在一些实施例中，所述碳原子数为8-18的胺基配体和/或羧基配体选自辛酸、辛胺、十二酸、十二胺、油酸、油胺中的至少一种。
第三种量子点发光二极管的制备方法，所述量子点发光二极管包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层，其中，所述电子传输层包括含有氧化锌的第一电子传输层，且至少第一电子传输层的一侧表面含有碳原子数为8-18的胺基配体和/或羧基配体；
其中，第一电子传输层的制备方法，包括：
在待制备第一电子传输层的预制器件基板上制备氧化锌预制薄膜；
在氧化锌预制薄膜的表面沉积碳原子数为8-18的胺基配体和/或羧基配体溶液后进行干燥处理，得到氧化锌薄膜。
在一些实施例中，所述碳原子数为8-18的胺基配体和/或羧基配体溶液的浓度为0.05-0.1mmol/L。
在一些实施例中，所述碳原子数为8-18的胺基配体和/或羧基配体的碳原子为8-12，且所述碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：每5mg氧化锌预制薄膜，沉积碳原子数为8-12的胺基配体和/或羧基配体溶液100μL-500μL。
在一些实施例中，所述碳原子数为8-18的胺基配体和/或羧基配体的碳原子为13-18，且所述碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：每5mg氧化锌预制薄膜，沉积碳原子数为13-18的胺基配体和/或羧基配体溶液50μL-300μL。
在一些实施例中，所述碳原子数为8-18的胺基配体和/或羧基配体选自丙酸、丙胺、丁酸、丁胺、己酸、己胺中的至少一种。
在一些实施例中，所述干燥处理的温度为10℃～100℃，干燥时间为10分钟～2小时。
在一些实施例中，所述第一电子传输层为金属掺杂氧化锌薄膜。
在一些实施例中，所述金属掺杂氧化锌薄膜中的掺杂金属离子选自Mg 2+、Mn 2+中的至少一种；或
所述金属掺杂氧化锌薄膜中的掺杂金属离子选自Al 3+、Y 3+、La 3+、Li +、Gd 3+、Zr 4+、Ce 4+中的至少一种。
在一些实施例中，所述掺杂金属离子的掺杂浓度如下：
当所述掺杂金属离子为Mg 2+时，所述金属掺杂氧化锌薄膜中Mg 2+摩尔含量占金属离子总摩尔量的0.1％～35％；
当所述掺杂金属离子为Mn 2+时，所述金属掺杂氧化锌薄膜中Mn 2+摩尔含量占金属离子总摩尔量的0.1％～30％；
当所述掺杂金属离子为Al 3+时，所述金属掺杂氧化锌薄膜中Al 3+摩尔含量占金属离子总摩尔量的0.1％～15％；
当所述掺杂金属离子为Y 3+时，所述金属掺杂氧化锌薄膜中Y 3+摩尔含量占金属离子总摩尔量的0.1％～10％；
当所述掺杂金属离子为La 3+时，所述金属掺杂氧化锌薄膜中La 3+摩尔含量占金属离子总摩尔量的0.1％～7％；
当所述掺杂金属离子为Li +时，所述金属掺杂氧化锌薄膜中Li +摩尔含量占金属离子总摩尔量的0.1％～45％；
当所述掺杂金属离子为Gd 3+时，所述金属掺杂氧化锌薄膜中Gd 3+摩尔含量占金属离子总摩尔量的0.01％～8％；
当所述掺杂金属离子为Zr 4+时，所述金属掺杂氧化锌薄膜中Zr 4+摩尔含量占金属离子总摩尔量的0.1％～45％；
当所述掺杂金属离子为Ce 4+时，所述金属掺杂氧化锌薄膜中Ce 4+摩尔含量占金属离子总摩尔量的0.1％～10％。
在一些实施例中，所述氧化锌预制薄膜的制备方法为：
将锌盐溶液与碱液混合反应，制备氧化锌纳米颗粒；将氧化锌纳米颗粒溶解，得到氧化锌胶体溶液；在所述预制器件基板上形成氧化锌胶体溶液，去除溶剂，制得氧化锌预制薄膜。
第四种量子点发光二极管的制备方法，所述量子点发光二极管包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层，其中，所述电子传输层包括第一电子传输层，且所述第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；
所述表面羟基量大于或等于0.6的氧化锌薄膜的制备方法，包括：
将锌盐溶液与第一碱液混合反应，制备氧化锌；将所述氧化锌溶解，得到氧化锌胶体溶液；向所述氧化锌胶体溶液加入第二碱液，调节所述氧化锌胶体溶液的pH大于或等于8，得到氧化锌溶液；
在待制备所述表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上形成氧化锌溶液，去除溶剂，制得表面羟基量大于或等于0.6的氧化锌薄膜。
在一些实施例中，所述在所述氧化锌胶体溶液加入第二碱液，调节所述氧化锌胶体溶液的pH大于或等于8的步骤中，向所述氧化锌胶体溶液加入第二碱液，使得到的混合溶液的pH值为9～12。
在一些实施例中，所述在所述氧化锌胶体溶液加入第二碱液，调节所述氧化锌胶体溶液的pH大于或等于8的步骤中，向所述氧化锌胶体溶液加入第二碱液，使得到的混合溶液的pH值为9～10。
在一些实施例中，所述第二碱液中的碱选自氢氧化钾、氢氧化钠、氢氧化锂、TMAH、氨水、乙醇胺、乙二胺中的至少一种。
在一些实施例中，所述第一碱液选自氢氧化钾、氢氧化钠、氢氧化锂、TMAH、氨水、乙醇胺、乙二胺中的至少一种形成的第一碱液。
在一些实施例中，所述锌盐溶液中的溶剂、所述第一碱液中的溶剂中的溶剂各自独立地选自水、有机醇、有机醚、砜中的至少一种。
在一些实施例中，所述第二碱液中的溶剂选自水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲 醚、DMSO中的至少一种。
在一些实施例中，所述表面羟基量大于或等于0.6的氧化锌薄膜为金属掺杂氧化锌薄膜，且所述锌盐溶液中还含有掺杂金属离子。
在一些实施例中，所述掺杂金属离子选自Mg 2+、Mn 2+中的至少一种；或
所述掺杂金属离子选自Al 3+、Y 3+、La 3+、Li +、Gd 3+、Zr 4+、Ce 4+中的至少一种。
在一些实施例中，所述掺杂金属离子的掺杂浓度如下：
当所述掺杂金属离子为Mg 2+时，所述锌盐溶液中Mg 2+摩尔含量占金属离子总摩尔量的0.1％～35％；
当所述掺杂金属离子为Mn 2+时，所述锌盐溶液中Mn 2+摩尔含量占金属离子总摩尔量的0.1％～30％；
当所述掺杂金属离子为Al 3+时，所述锌盐溶液中Al 3+摩尔含量占金属离子总摩尔量的0.1％～15％；
当所述掺杂金属离子为Y 3+时，所述锌盐溶液中Y 3+摩尔含量占金属离子总摩尔量的0.1％～10％；
当所述掺杂金属离子为La 3+时，所述锌盐溶液中La 3+摩尔含量占金属离子总摩尔量的0.1％～7％；
当所述掺杂金属离子为Li +时，所述锌盐溶液中Li +摩尔含量占金属离子总摩尔量的0.1％～45％；
当所述掺杂金属离子为Gd 3+时，所述锌盐溶液中Gd 3+摩尔含量占金属离子总摩尔量的0.01％～8％；
当所述掺杂金属离子为Zr 4+时，所述锌盐溶液中Zr 4+摩尔含量占金属离子总摩尔量的0.1％～45％；
当所述掺杂金属离子为Ce 4+时，所述锌盐溶液中Ce 4+摩尔含量占金属离子总摩尔量的0.1％～10％。
在一些实施例中，所述锌盐溶液与第一碱液混合的步骤中，所述锌盐溶液与所述第一碱液的添加量满足：金属离子的摩尔量与化合价数的乘积与氢氧根离子的摩尔量之比为0.75：1～1.25:1。
第五种量子点发光二极管的制备方法，所述量子点发光二极管包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层，其中，所述电子传输层包括第一电子传输层，所述第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；
所述表面羟基量大于或等于0.6的氧化锌薄膜的制备方法，包括：
在待制备所述表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上制备氧化锌预制薄膜；
在所述氧化锌预制薄膜的表面沉积第二碱液后进行干燥处理，得到氧化锌薄膜。
在一些实施例中，所述第二碱液选自氢氧化钾、氢氧化钠、氢氧化锂、TMAH、氨水、乙醇胺、乙二胺中的至少一种形成的碱液。
在一些实施例中，所述第二碱液的浓度为0.05-0.5mmol/L。
在一些实施例中，所述第二碱液中的碱为无机碱，且所述第二碱液的浓度为0.05-0.1mmol/L。
在一些实施例中，所述在所述氧化锌预制薄膜的表面沉积第二碱液的步骤中，所述第二碱液的添加量满足：每5mg氧化锌预制薄膜，使用50μL-400μL的第二碱液进行处理。
在一些实施例中，所述第二碱液中的碱为有机碱，且所述第二碱液的浓度为0.2-0.4mmol/L。
在一些实施例中，所述在所述氧化锌预制薄膜的表面沉积第二碱液的步骤中，所述第二碱液的添加量满足：每5mg氧化锌预制薄膜，使用500μL-1000μL的第二碱液进行处理。
在一些实施例中，所述干燥处理的温度为10℃～100℃，干燥时间为10分钟～2小时。
在一些实施例中，所述表面羟基量大于或等于0.6的氧化锌薄膜为金属掺杂氧化锌薄膜。
在一些实施例中，所述金属掺杂氧化锌薄膜中的掺杂金属离子选自Mg 2+、Mn 2+中的至少一种；或
所述金属掺杂氧化锌薄膜中的掺杂金属离子选自Al 3+、Y 3+、La 3+、Li +、Gd 3+、Zr 4+、Ce 4+中的至少一种。
在一些实施例中，所述掺杂金属离子的掺杂浓度如下：
当所述掺杂金属离子为Mg 2+时，所述金属掺杂氧化锌薄膜中Mg 2+摩尔含量占金属离子总摩尔量的0.1％～35％；
当所述掺杂金属离子为Mn 2+时，所述金属掺杂氧化锌薄膜中Mn 2+摩尔含量占金属离子总摩尔量的0.1％～30％；
当所述掺杂金属离子为Al 3+时，所述金属掺杂氧化锌薄膜中Al 3+摩尔含量占金属离子总摩尔量的0.1％～15％；
当所述掺杂金属离子为Y 3+时，所述金属掺杂氧化锌薄膜中Y 3+摩尔含量占金属离子总摩尔量的0.1％～10％；
当所述掺杂金属离子为La 3+时，所述金属掺杂氧化锌薄膜中La 3+摩尔含量占金属离子总摩尔量的0.1％～7％；
当所述掺杂金属离子为Li +时，所述金属掺杂氧化锌薄膜中Li +摩尔含量占金属离子总摩尔量的0.1％～45％；
当所述掺杂金属离子为Gd 3+时，所述金属掺杂氧化锌薄膜中Gd 3+摩尔含量占金属离子总摩尔量的0.01％～8％；
当所述掺杂金属离子为Zr 4+时，所述金属掺杂氧化锌薄膜中Zr 4+摩尔含量占金属离子总摩尔量的0.1％～45％；
当所述掺杂金属离子为Ce 4+时，所述金属掺杂氧化锌薄膜中Ce 4+摩尔含量占金属离子总摩尔量的0.1％～10％。
有益效果
本申请提供的量子点发光二极管，利用表面羟基量大于或等于0.6的氧化锌薄膜作为第一电子传输层，抑制电子在电子传输层中的传输，降低电子在量子点发光二极管中的传输，从而减少量子点发光层中注入的电子，实现量子点发光二极管中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管；而电子传输层含有氧化锌，且至少部分所述氧化锌的表面含有碳原子数为8-18的胺基配体和/或羧基配体时，由于配位的碳原子数为8-18的胺基配体和/或羧基配体的链长较长，在空间位阻效应的作用下，增加了薄膜中氧化锌纳米颗粒之间的距离，进而降低了电子传输层的电子迁移率，抑制电子在电子传输层中的传输，降低电子在量子点发光二极管中的传输，从而减少量子点发光层中注入的电子，实现量子点发光二极管中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管。
本申请提供的量子点发光二极管的制备方法，降低了电子传输层的电子迁移率，抑制电子在电子传输层中的传输，降低电子在量子点发光二极管中的传输，从而减少量子点发光层中注入的电子，实现量子点发光二极管中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例或现有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性的前提下，还可以根据这些附图获得其他的附图。
图1是本申请实施例提供的一种电子传输层的结构示意图；
图2是本申请实施例提供的另一种电子传输层的结构示意图；
图3是本申请实施例提供的发光二极管的结构示意图；
图4是本申请实施例提供的正置发光二极管的结构示意图；
图5是本申请实施例提供的倒置发光二极管的结构示意图；
图6是本申请实施例提供的表面羟基量大于或等于0.6的氧化锌薄膜的第一种制备工艺流程图；
图7是本申请实施例提供的表面羟基量大于或等于0.6的氧化锌薄膜的第二种制备工艺流程图；
图8是本申请实施例提供的表面羟基量大于或等于0.6的氧化锌薄膜的第三种制备工艺流程图；
图9是本申请实施例提供的以表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌作为电子传输材料的第一电子传输层的第一种制备工艺流程图；
图10是本申请实施例提供的以表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌作为电子传输材料的第一电子传输层的第二种制备工艺流程图；
图11是本申请实施例提供的利用X射线光电子能谱(XPS)测试羟基氧峰面积与晶格氧峰面积，计算两者之比得到羟基含量的示意图；
图12是本申请实施例提供的EQE-亮度曲线图；
图13是本申请实施例提供的表征器件寿命的示意图；
图14是本申请实施例1和对比例1提供的量子点发光二极管的器件EQE测试结果图；
图15是本申请实施例2和对比例1提供的量子点发光二极管的器件EQE测试结果图；
图16是本申请实施例2和对比例1提供的量子点发光二极管的寿命测试结果图；
图17是本申请实施例3和对比例1提供的量子点发光二极管的器件EQE测试结果图；
图18是本申请实施例3和对比例1提供的量子点发光二极管的寿命测试结果图；
图19是本申请实施例4和对比例2提供的量子点发光二极管的EQE测试结果图；
图20是本申请实施例5和对比例2提供的量子点发光二极管的EQE测试结果图；
图21是本申请实施例6和对比例2提供的量子点发光二极管的EQE测试结果图；
图22是本申请实施例7和对比例2提供的量子点发光二极管的EQE测试结果图。
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。
在本申请的描述中，需要理解的是，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括一个或者更多个该特征。在本申请的描述中，“多个”的含义是两个或两个以上，除非另有明确具体的限定。
量子点发光二极管器件中，氧化锌层的电子迁移率往往要高于空穴传输层的空穴迁移率。为了在量子点发光二极管器件中实现较好的载流子注入平衡，传统方案中通过在量子点发光层和氧化锌层之间插入电子阻挡层等手段降低氧化锌层电子迁移率，使得量子点发光层中注入的电子和空穴达到平衡。但是，利用插入电子阻挡层等改变器件结构的方法来改善载流子注入平衡存在着一定的局限性。这种方法一方面在实际器件制备中较难实现，这是由于电子阻挡层有着严格的厚度要求，过厚或者过薄都难以起到有效的作用，甚至会降低量子点发光二极管的器件性能，因此在实际操作中较难控制。另一方面，改变器件结构(增加电子阻挡层)的方法也会增加器件的制备成本，在将来的量子点发光二极管器件量产时增加成本负担。
有鉴于此，一方面本申请通过调控氧化锌薄膜表面的羟基量，来实现电子注入速率的调控，减少量子点发光层中注入的电子，实现了量子点发光二极管中载流子的注入平衡，最终得到了具有较高外量子效率的量子点发光二极管器件。具体的，本申请提供的量子点发光二极管，利用表面羟基量较多的氧化锌薄膜作为电子传输层。在这种情况下，由于电子向量子点发光层注入的速率降低，使得空穴和电子的注入更加平衡，使得器件外量子效率得到提升。
应当说明的是，本申请实施例中，氧化锌薄膜表面羟基量的测定，利用X射线光电子能谱(XPS)对氧化锌薄膜进行检测获得。具体的，X射线光电子能谱(XPS)检测结果中，O1s能谱可以通过分峰得到三个子峰，分别为代表氧化锌晶体中氧原子摩尔浓度的OM峰(峰位在529ev-531ev之间)，代表氧化锌晶体中氧空位摩尔浓度的OV峰(峰位在531ev-532ev)，和代表氧化锌晶体表面上羟基配体摩尔浓度的OH峰(峰位在532ev-534ev)。各个子峰之间的面积比代表氧化锌薄膜中不同种类氧原子的摩尔浓度之比，因此定义氧化锌薄膜表面羟基量为：OH峰面积/OM峰的面积，即氧化锌薄膜表面羟基量为：氧化锌薄膜表面上羟基配体的摩尔浓度与氧化锌晶体中氧原子摩尔浓度的比值。
本申请实施例提供的量子点发光二极管，包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层；
其中，所述电子传输层包括第一电子传输层，且所述第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜。
在一种可能的实施方式中，电子传输层只包括一层薄膜，且该薄膜为表面羟基量大于或等于0.6的氧化锌薄膜，即电子传输层为第一电子传输层。在这种情况下，由于氧化锌表面吸附有大量带负电的羟基基团，会对电子在氧化锌薄膜中的传输起到一定的抑制和阻碍作用，可以减少量子点发光层中注入的电子，使得量子点发光二极管器件在工作初期的电子注入效率较低，实现量子点发光二极管器件中载流 子的注入平衡，器件处于载流子相同平衡的状态，因而具有较高的外量子效率。
电子传输层为第一电子传输层时，第一电子传输层中的氧化锌为掺杂金属或未掺杂金属的氧化锌。
在一些实施例中，第一电子传输层为不含掺杂金属的氧化锌薄膜，即电子传输层由氧化锌制成，氧化锌中不含有掺杂金属。在一些实施例中，未掺杂氧化锌薄膜的表面羟基量大于或等于0.8；在一些实施例中，未掺杂氧化锌薄膜的表面羟基量大于或等于1.0。应当注意的是，本申请实施例所指的未掺杂氧化锌薄膜，是相对金属掺杂氧化锌薄膜的氧化锌薄膜，是指形成氧化锌薄膜的氧化锌中，不掺杂有其他金属离子。即未掺杂氧化锌薄膜为纯氧化锌薄膜。
在一些实施例中，第一电子传输层为含有掺杂金属的氧化锌薄膜，即电子传输层中的氧化锌为含有掺杂金属的氧化锌。应当理解的是，本申请所指的掺杂金属，是指以离子形式掺杂进入氧化锌中的不同于锌离子的其他金属离子。通过在氧化锌中掺杂金属元素得到的掺杂氧化锌，用作量子点发光二极管的电子传输层材料时，有利于量子点发光二极管器件得到较高的器件效率，但是器件寿命却不理想，甚至要差于不掺杂的纯氧化锌电子传输层的量子点发光二极管的器件寿命。这是因为掺杂氧化锌电子传输层在能级/氧空位(电子迁移率)改变的同时，掺杂离子进入氧化锌颗粒的表面后会优先填充至表面缺陷处，一定程度上起到钝化缺陷的目的，而新填充的掺杂离子位点会配位新的表面羟基，因而总的表面羟基量会增加。
在一些实施例中，含有掺杂金属的氧化锌薄膜的表面羟基量大于或等于0.8；在一些实施例中，含有掺杂金属的氧化锌薄膜的表面羟基量大于或等于1.0。
在一些实施例中，含有掺杂金属的氧化锌薄膜中的掺杂金属选自Mg 2+、Mn 2+中的至少一种。在这种情况下，掺杂金属离子和锌离子具有相同价态，但是其氧化物具有不同导带能级的金属离子，此时，掺杂这种金属离子可以对氧化锌电子传输层的导带能级进行调整，进而优化量子点发光二极管器件中量子点发光层和电子传输层之间的能级匹配，提高器件的EQE。
在一些实施例中，含有掺杂金属的氧化锌薄膜中的掺杂金属选自Al 3+、Y 3+、La 3+、Li +、Gd 3+、Zr 4+、Ce 4+中的至少一种。在这种情况下，掺杂金属离子与锌离子具有不同价态的金属离子，通过掺杂该种金属离子可以对氧化锌电子传输层的氧空位(电子迁移率)进行调整，进而优化QLED器件的载流子注入平衡，提高器件的EQE。
掺杂金属离子的离子半径与锌离子半径存在一定差异，且两者氧化物的晶体结构存在不同(示例性的，MgO和MnO为NaCl型立方晶系，ZrO 2为单斜晶系等，而ZnO为纤锌矿型六方晶系)，使得掺杂金属离子在氧化锌材料中存在有掺杂极限。当掺杂量超过掺杂极限时，掺杂金属离子会以第二相的形式从氧化锌材料的表面析出，进而对氧化锌材料的性能产生不利的影响。本申请实施例提供的掺杂金属离子与锌离子的离子半径对比如下表1所示。
表1
Figure PCTCN2021143433-appb-000001
本申请实施例根据所选掺杂金属离子与Zn 2+离子半径差异对掺杂金属离子的掺杂量进行调控，且掺杂金属离子的离子半径与锌离子的离子半径越接近以及两者氧化物的晶体结构越相似，掺杂金属离子 在氧化锌材料中的掺杂极限就越高。示例性的：当掺杂金属为Mg 2+时，含有掺杂金属的氧化锌薄膜中Mg 2+的掺杂摩尔浓度为0.1％～35％；当掺杂金属为Mn 2+时，含有掺杂金属的氧化锌薄膜中Mn 2+的掺杂摩尔浓度为0.1％～30％；当掺杂金属为Al 3+时，含有掺杂金属的氧化锌薄膜中Al 3+的掺杂摩尔浓度为0.1％～15％；当掺杂金属为Y 3+时，含有掺杂金属的氧化锌薄膜中Y 3+的掺杂摩尔浓度为0.1％～10％；当掺杂金属为La 3+时，含有掺杂金属的氧化锌薄膜中La 3+的掺杂摩尔浓度为0.1％～7％；当掺杂金属为Li +时，含有掺杂金属的氧化锌薄膜中Li +的掺杂摩尔浓度为0.1％～45％；当掺杂金属为Gd 3+时，含有掺杂金属的氧化锌薄膜中Gd 3+的掺杂摩尔浓度为0.01％～8％；当掺杂金属为Zr 4+时，含有掺杂金属的氧化锌薄膜中Zr 4+的掺杂摩尔浓度为0.1％～45％；当掺杂金属为Ce 4+时，含有掺杂金属的氧化锌薄膜中Ce 4+的掺杂摩尔浓度为0.1％～10％。
在一些实施例中，电子传输层为第一电子传输层时，第一电子传输层即电子传输层的厚度为10～100nm。
在一种可能的实施方式中，电子传输层还包括第二电子传输层，且第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜。即电子传输层同时包括表面羟基量小于或等于0.4的氧化锌薄膜和表面羟基量大于或等于0.6的氧化锌薄膜，两者沿着垂直于量子点发光层或阴极的方向层叠设置。在这种情况下，使用双层氧化锌电子传输时，其中，表面高羟基量的氧化锌薄膜，可以减少量子点发光层中注入的电子，使得量子点发光二极管器件在工作初期的电子注入效率较低，实现量子点发光二极管器件中载流子的注入平衡，器件处于载流子相同平衡的状态，因而具有较高的外量子效率；而量子点发光二极管器件在持续工作到稳定状态时，由于低表面羟基量氧化锌薄膜的存在，使得量子点发光层带负电的状态依然会发生，并且达到动态平衡，进而使得最终电子注入效率处于较低的水平，与空穴注入效率构成载流子注入平衡，因此得到的量子点发光二极管器件寿命也会有所改善。
第一电子传输层和第二电子传输层层叠设置，两者的相对位置可以灵活设置。在一些实施例中，第二电子传输层设置在第一电子传输层靠近量子点发光层的一侧表面。在这种情况下，表面羟基量较少的氧化锌胶体溶液沉积在量子点发光层上时，有利于得到更加平整的氧化锌薄膜。在一些实施例中，第二电子传输层设置在第一电子传输层靠近量子点发光层的一侧表面。
在一些实施例中，第一电子传输层和第二电子传输层中的氧化锌均为未掺杂的氧化锌。即第一电子传输层和第二电子传输层由氧化锌制成，氧化锌中不含有掺杂金属。在一些实施例中，电子传输层由表面羟基量大于或等于0.6的氧化锌薄膜即第一电子传输层和表面羟基量小于或等于0.4的氧化锌薄膜即第二电子传输层组成。在一些实施例中，第一电子传输层的表面羟基量大于或等于0.8，第二电子传输层的表面羟基量小于或等于0.25，甚至小于或等于0.15；在一些实施例中，第一电子传输层的表面羟基量大于或等于1.0，第二电子传输层的表面羟基量小于或等于0.25，甚至小于或等于0.15。
在一些实施例中，第一电子传输层和第二电子传输层中的至少一层中的氧化锌为金属掺杂氧化锌。
在一些实施例中，表面羟基量大于或等于0.6的氧化锌薄膜中的氧化锌为金属掺杂氧化锌，表面羟基量小于或等于0.4的氧化锌薄膜即第二电子传输层为未掺杂氧化锌薄膜。在这种情况下，如上文，一方面，低羟基量使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命。另一方面，高羟基量可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管器件。此外，在表面羟基量大于或等于0.6的氧化锌中掺杂金属离子，来实现有效的载流子注入调控，器件工作初期可以得到比未掺杂氧化锌薄膜作为电子传输层的量子点发光二极管器件更高的EQE，加之第一电子传输层的表面羟基量大于或等于0.6，两者协同，可以更有效地提高量子点发光二极管器件的EQE。本实施例通过调控氧化锌薄膜表面羟基量即可实现QLED器件的载流子注入平衡，无需改变器件结构(插入电子阻挡层)，也无需通过掺杂等手段对氧化锌薄膜进行改性，整个过程操作简单，成本低廉，具有良好的可重复性。
示例性的，电子传输层由第一电子传输层和表面羟基量小于或等于0.4的未掺杂氧化锌薄膜(第二电子传输层)组成，且第一电子传输层中的氧化锌为金属掺杂氧化锌。在一些实施例中，第一电子传输层的表面羟基量大于或等于0.8，第二电子传输层的表面羟基量小于或等于0.25，甚至小于或等于0.15； 在一些实施例中，第一电子传输层的表面羟基量大于或等于1.0，第二电子传输层的表面羟基量小于或等于0.25，甚至小于或等于0.15。
在一些实施例中，表面羟基量大于或等于0.6的氧化锌薄膜即第一电子传输层为未掺杂氧化锌薄膜，表面羟基量小于或等于0.4的氧化锌薄膜即第二电子传输层中的氧化锌为金属掺杂氧化锌。在这种情况下，一方面，低羟基量使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命。另一方面，高羟基量可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管器件。此外，在表面羟基量小于或等于0.4的氧化锌中掺杂金属离子，来实现有效的载流子注入调控，器件工作初期可以得到比未掺杂氧化锌薄膜作为电子传输层的量子点发光二极管器件更高的EQE，加之第一电子传输层的表面羟基量大于或等于0.6，两者协同，可以更有效地提高量子点发光二极管器件的EQE。
示例性的，电子传输层由表面羟基量大于或等于0.6的未掺杂氧化锌薄膜(第一电子传输层)和表面羟基量小于或等于0.4的氧化锌薄膜(第二电子传输层)组成，且第二电子传输层中的氧化锌为金属掺杂氧化锌。在一些实施例中，第一电子传输层的表面羟基量大于或等于0.8，第二电子传输层的表面羟基量小于或等于0.25，甚至小于或等于0.15；在一些实施例中，第一电子传输层的表面羟基量大于或等于1.0，第二电子传输层的表面羟基量小于或等于0.25，甚至小于或等于0.15。
在一些实施例中，表面羟基量大于或等于0.6的氧化锌薄膜即第一电子传输层中的氧化锌为金属掺杂氧化锌，表面羟基量小于或等于0.4的氧化锌薄膜即第二电子传输层中的氧化锌为金属掺杂氧化锌。在这种情况下，一方面，低羟基量使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命。另一方面，高羟基量可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管器件。此外，在表面羟基量大于或等于0.6的氧化锌和表面羟基量小于或等于0.4的氧化锌中均掺杂金属离子，来实现有效的载流子注入调控，器件工作初期可以得到比未掺杂氧化锌薄膜作为电子传输层的量子点发光二极管器件更高的EQE，加之第一电子传输层的表面羟基量大于或等于0.6，三者协同，可以显著提高量子点发光二极管器件的EQE。
示例性的，电子传输层由表面羟基量大于或等于0.6的氧化锌薄膜(第一电子传输层)和表面羟基量小于或等于0.4的氧化锌薄膜(第二电子传输层)组成，且第一电子传输层核第二电子传输层中的氧化锌均为金属掺杂氧化锌。在一些实施例中，第一电子传输层的表面羟基量大于或等于0.8，第二电子传输层的表面羟基量小于或等于0.25，甚至小于或等于0.15；在一些实施例中，第一电子传输层的表面羟基量大于或等于1.0，第二电子传输层的表面羟基量小于或等于0.25，甚至小于或等于0.15。
上述实施例的一种实施方式中，如图1所示，电子传输层50由第一电子传输层51和第二电子传输层52组成，且第二电子传输层52较第一电子传输层51更靠近量子点发光层40，即第一电子传输层51靠近阴极60。在这种情况下，表面羟基量较少的氧化锌胶体溶液沉积在量子点发光层上时，有利于得到更加平整的氧化锌薄膜。
在一些实施例中，电子传输层包括第一电子传输层和第二电子传输层，第二电子传输层设置在第一电子传输层靠近阴极或量子点发光层的一侧表面，且第二电子传输层为金属掺杂氧化锌薄膜。在这种情况下，通过掺杂氧化锌的能级匹配优化或者电子迁移率优化，同时提高氧化锌表面羟基量，来优化量子点发光二极管的外量子效率(EQE)。
示例性的，如图1所示，电子传输层50包括第一电子传输层51和第二电子传输层52，第二电子传输层52为金属掺杂氧化锌薄膜，且第二电子传输层52设置在第一电子传输层51靠近量子点发光层40的一侧表面，即第一电子传输层51靠近阴极60。在这种情况下，掺杂金属氧化锌胶体溶液沉积在量子点发光层上时，有利于得到更加平整的氧化锌薄膜。在上述实施例中，当电子传输层为双层氧化锌薄膜式，每层氧化锌薄膜的厚度为10～100nm。在这种情况下，氧化锌薄膜厚度合适，不容易被电子击穿，有利于保持电子传输层的注入性能、成膜质量及表面平整性。考虑到表面羟基量大于或等于0.6的氧化锌薄膜或者金属掺杂氧化锌薄膜，由于其电子迁移率较低，因此薄膜厚度不宜过厚。示例性的，表面羟基量大于或等于0.6的氧化锌薄膜或者金属掺杂氧化锌薄膜的厚度为10-30nm。表面羟基量小于或等于 0.4的氧化锌薄膜，由于其电子迁移率较高，因此薄膜厚度可以适当厚些。示例性的，表面羟基量小于或等于0.4的氧化锌薄膜或者金属掺杂氧化锌薄膜的厚度为20-60nm。
在上述实施例的一些实施例中，电子传输层包括n个由第一电子传输层和第二电子传输层组成的薄膜叠层单元，其中，n大于或等于2。电子传输层采用叠层方式，可能使得能级匹配更佳，使器件寿命提升幅度更大。在一些实施例中，n为大于或等于2且小于或等于9的整数。
在一种可能的实施方式中，电子传输层还包括第三电子传输层。即电子传输层包括表面羟基量大于或等于0.6的氧化锌薄膜即第一电子传输层，第二电子传输层，以及第三电子传输层。其中，第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜、表面羟基量大于或等于0.6的氧化锌薄膜或金属掺杂氧化锌薄膜。
在一种实施方式中，第三电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜。
在一些实施例中，电子传输层包括表面羟基量大于或等于0.6的氧化锌薄膜(即第一电子传输层)，表面羟基量小于或等于0.4的氧化锌薄膜(即第二电子传输层)，以及表面羟基量大于或等于0.6的氧化锌薄膜(即第三电子传输层)，其中，所述第三电子传输层设置在所述第二电子传输层背离所述第一电子传输层的一侧表面。在这种情况下，一层低羟基量的氧化锌薄膜使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命；而两层高羟基量的氧化锌薄膜可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管器件。
在一种实施方式中，第三电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜。
在一些实施例中，如图2所示，电子传输层50包括表面羟基量大于或等于0.6的氧化锌薄膜(即第一电子传输层51)，表面羟基量小于或等于0.4的氧化锌薄膜(即第二电子传输层52)，以及表面羟基量小于或等于0.4的氧化锌薄膜(即第三电子传输层53)，且所述第三电子传输层53设置在所述第一电子传输层51背离所述第二电子传输层52的一侧表面。在这种情况下，双层低羟基量的氧化锌薄膜使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命；而高羟基量的氧化锌薄膜可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管器件。此外，由于表面羟基量较少的氧化锌或者掺杂氧化锌胶体溶液沉积在量子点发光层上时，有利于得到更加平整的氧化锌薄膜。由此，得到的量子点发光二极管器件兼具良好的EQE和器件寿命。
在一些实施例中，电子传输层包括表面羟基量大于或等于0.6的氧化锌薄膜(即第一电子传输层)，金属掺杂氧化锌薄膜(第二电子传输层)，以及表面羟基量小于或等于0.4的氧化锌薄膜(即第三电子传输层)，且所述第三电子传输层设置在所述第二电子传输层和所述第一电子传输层之间。在这种情况下，一方面，低羟基量使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命。另一方面，高羟基量可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管器件。此外，第二电子传输层的氧化锌中掺杂金属离子，来实现有效的载流子注入调控，器件工作初期可以得到比未掺杂氧化锌薄膜作为电子传输层的量子点发光二极管器件更高的EQE，可以更显著提高量子点发光二极管器件的EQE。
在一些实施方式中，第三电子传输层为金属掺杂氧化锌薄膜。
在一些实施例中，电子传输层包括表面羟基量大于或等于0.6的氧化锌薄膜(即第一电子传输层)，表面羟基量小于或等于0.4的氧化锌薄膜(即第二电子传输层)，以及金属掺杂氧化锌薄膜(第三电子传输层)，且所述第三电子传输层设置在所述第二电子传输层背离所述第一电子传输层的一侧表面。在这种情况下，低羟基量的氧化锌薄膜使电子迁移率得到了进一步的加强，从而使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命；而高羟基量的氧化锌薄膜可以减少量子点发光层中注入的电子，实现量子点发光二极管器件工作初期载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管器件。同时，通过掺杂氧化锌的能级匹配优化或者电子迁移率优化，量子点发光二极管器件已经处在较优的载流子注入平衡下，器件工作初期可以得到 比未掺杂氧化锌薄膜作为电子传输层的量子点发光二极管器件更高的外量子效率(EQE)；而由于掺杂氧化锌薄膜表面羟基量较低的原因，使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态。由此可以使得量子点发光二极管获得更好的器件寿命，并在工作初期保有较高EQE。在一些实施例中，第三电子传输层邻近量子点发光层设置。由于掺杂氧化锌胶体溶液沉积在量子点发光层上时，有利于得到更加平整的氧化锌薄膜。
应当理解的是，电子传输层含有第三电子传输层的实施例中，表面羟基量小于或等于0.4的氧化锌薄膜中的氧化锌可以是未掺杂氧化锌，也可以是金属掺杂氧化锌；同样的，表面羟基量大于或等于0.6的氧化锌薄膜中的氧化锌可以是未掺杂氧化锌，也可以是金属掺杂氧化锌。
电子传输层含有第三电子传输层的实施例中，在一些实施例中，电子传输层的厚度为10～100nm。在一些实施例中，表面羟基量小于或等于0.4的氧化锌薄膜的厚度为20-60nm。在一些实施例中，表面羟基量大于或等于0.6的氧化锌薄膜的厚度为10-30nm。在一些实施例中，金属掺杂氧化锌薄膜的厚度为10-30nm。各层厚度在此范围内，使得在这种情况下，氧化锌薄膜厚度合适，不容易被电子击穿，有利于保持电子传输层的注入性能、成膜质量及表面平整性。特别的，表面羟基量大于或等于0.6的氧化锌薄膜或者金属掺杂氧化锌薄膜，由于其电子迁移率较低，因此薄膜厚度相对较薄；表面羟基量小于或等于0.4的氧化锌薄膜，由于其电子迁移率较高，因此薄膜厚度相对较厚。
电子传输层含有第二电子传输层，且第二电子传输层为金属掺杂氧化锌薄膜的实施例，以及电子传输层含有第二电子传输层和第三电子传输层，且第二电子传输层和/或第三电子传输层为金属掺杂氧化锌薄膜的实施例中，在一些实施例中，金属掺杂氧化锌薄膜中的掺杂金属的类型、掺杂金属带来的影响以及掺杂金属的掺杂含量如上文(电子传输层为第一电子传输层的情形)所述，为了节约篇幅，此处不再赘述。
在一些实施例中，金属掺杂氧化锌薄膜中的掺杂金属选自Mg 2+、Mn 2+中的至少一种。在一些实施例中，金属掺杂氧化锌薄膜中的掺杂金属选自Al 3+、Y 3+、La 3+、Li +、Gd 3+、Zr 4+、Ce 4+中的至少一种。
在一些实施例中，当掺杂金属为Mg 2+时，金属掺杂氧化锌薄膜中Mg 2+的掺杂摩尔浓度为0.1％～35％；当掺杂金属为Mn 2+时，金属掺杂氧化锌薄膜中Mn 2+的掺杂摩尔浓度为0.1％～30％；当掺杂金属为Al 3+时，金属掺杂氧化锌薄膜中Al 3+的掺杂摩尔浓度为0.1％～15％；当掺杂金属为Y 3+时，金属掺杂氧化锌薄膜中Y 3+的掺杂摩尔浓度为0.1％～10％；当掺杂金属为La 3+时，金属掺杂氧化锌薄膜中La 3+的掺杂摩尔浓度为0.1％～7％；当掺杂金属为Li +时，金属掺杂氧化锌薄膜中Li +的掺杂摩尔浓度为0.1％～45％；当掺杂金属为Gd 3+时，金属掺杂氧化锌薄膜中Gd 3+的掺杂摩尔浓度为0.01％～8％；当掺杂金属为Zr 4+时，金属掺杂氧化锌薄膜中Zr 4+的掺杂摩尔浓度为0.1％～45％；当掺杂金属为Ce 4+时，金属掺杂氧化锌薄膜中Ce 4+的掺杂摩尔浓度为0.1％～10％。
本申请实施例提供的量子点发光二极管，利用表面羟基量大于或等于0.6的氧化锌薄膜作为第一电子传输层，抑制电子在电子传输层中的传输，降低电子在量子点发光二极管中的传输，从而减少量子点发光层中注入的电子，实现量子点发光二极管中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管。本申请提供的量子点发光二极管，只需要通过调控氧化锌薄膜表面羟基量即可实现量子点发光二极管器件的载流子注入平衡，无需改变器件结构(插入电子阻挡层)，也无需通过掺杂等手段对氧化锌薄膜进行改性，整个过程操作简单，成本低廉，具有良好的可重复性。
另一方面，本申请实施例提供一种量子点发光二极管，包括相对设置的阳极和阴极，设置在阳极和阴极之间的量子点发光层，设置在量子点发光层和阴极之间的电子传输层；
其中，电子传输层含有氧化锌，且至少部分氧化锌的表面含有碳原子数为8-18的胺基配体和/或羧基配体。
电子传输层中，由于与氧化锌配位的碳原子数为8-18的胺基配体和/或羧基配体的链长较长，在空间位阻效应的作用下，增加了薄膜中氧化锌纳米颗粒之间的距离，进而降低了电子传输层的电子迁移率，抑制电子在电子传输层中的传输，降低电子在量子点发光二极管中的传输，从而减少量子点发光层中注入的电子，实现量子点发光二极管中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管。
本申请实施例中，胺基配体和/或羧基配体的链长即碳原子数量需要严格控制。当链长过短时，不易增加氧化锌纳米颗粒之间的距离，进而不易起到降低电子传输层的电子迁移率的作用；而当链长过长时，由于配体的极性较弱，不易有效分散在极性较强的氧化锌胶体溶液中，通过配体交换结合在氧化锌纳米颗粒的表面。示例性的，碳原子数为8-18的胺基配体和/或羧基配体选自辛酸、辛胺、十二酸、十二胺、油酸、油胺中的至少一种。在一些实施例中，胺基配体和/或羧基配体的碳原子数为8-12，从而在降低电子传输层的电子迁移率的同时，兼具较好的薄膜品质。
在一些实施例中，电子传输层包括含有氧化锌的第一电子传输层，且形成第一电子传输层的氧化锌表面含有碳原子数为8-18的胺基配体和/或羧基配体。胺基配体和/或羧基配体的引入，可以增加成膜后氧化锌纳米颗粒之间的距离，进而降低了成膜后的第一电子传输层的电子迁移率。
在一些实施例中，表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜中，碳原子数为8-18的胺基配体和/或羧基配体与氧化锌的摩尔比为1:4～10:1。在这种情况下，氧化锌纳米颗粒表面的胺基配体和/或羧基配体量合适，可以使含有氧化锌的电子传输层的电子迁移率降低，使量子点发光层中的电子和空穴趋向平衡，从而提高量子点发光二极管的外量子效率。当配体链长较长(13-18)时，配体交换后样品的电子迁移率会有的下降，因此链长较长的配体添加量不多时也可以达到降低电子迁移率，提高EQE的目的，此外链长较长配体添加量过多时，会降低氧化锌纳米颗粒在极性溶剂中的溶解性，影响最终器件中氧化锌层的成膜性，降低最终器件的器件性能；而当配体链长较短(8-12)时，配体交换后电子迁移率下降的幅度较小，因此链长较多配体的添加量需要高一些才能实现提高EQE的目的。在一些实施例中，胺基配体和/或羧基配体的碳原子数为8-12，胺基配体和/或羧基配体与氧化锌纳米颗粒的摩尔比选为1:1～10:1；在一些实施例中，胺基配体和/或羧基配体的碳原子数为13-18，胺基配体和/或羧基配体与氧化锌纳米颗粒的摩尔比选为1:4～5:1。
在一种可能的实施方式中，电子传输层只包括一层薄膜，且该薄膜为第一电子传输层，即形成电子传输层的材料为氧化锌，且氧化锌表面含有碳原子数为8-18的胺基配体和/或羧基配体。在这种情况下，电子传输层中的电子向量子点发光层的传输阻力大，电子向量子点发光层的注入速率相降低，较低的电子注入速率与空穴注入速率有利于载流子注入平衡，使得量子点发光二极管器件的外量子效率得到提升。
在一些实施例中，第一电子传输层中的氧化锌为未掺杂氧化锌，即电子传输层由表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌制成，氧化锌中不含有掺杂金属。应当注意的是，本申请实施例所指的未掺杂氧化锌薄膜，是相对金属掺杂氧化锌薄膜的氧化锌薄膜，是指形成氧化锌薄膜的氧化锌中，不掺杂有其他金属离子。即未掺杂氧化锌薄膜为纯氧化锌薄膜。
在一些实施例中，第一电子传输层中的氧化锌为金属掺杂氧化锌，即电子传输层中的氧化锌为含有掺杂金属的氧化锌。应当理解的是，本申请所指的掺杂金属，是指以离子形式掺杂进入氧化锌中的不同于锌离子的其他金属离子。通过在氧化锌中掺杂金属元素得到的掺杂氧化锌，用作量子点发光二极管的电子传输层材料时，有利于量子点发光二极管器件得到较高的器件效率，但是器件寿命却不理想，甚至要差于不掺杂的纯氧化锌电子传输层的量子点发光二极管的器件寿命。具体的，与未掺杂氧化锌薄膜表面羟基量调整对比，针对掺杂氧化锌薄膜表面羟基量进行调整时，通过掺杂氧化锌的能级匹配优化或者电子迁移率优化，量子点发光二极管器件已经处在较优的载流子注入平衡下，器件工作初期可以得到比未掺杂氧化锌薄膜作为电子传输层的量子点发光二极管器件更高的外量子效率(EQE)。
金属掺杂氧化锌薄膜中的掺杂金属的类型、掺杂金属带来的影响以及掺杂金属的掺杂含量如上文(电子传输层为第一电子传输层的情形)所述，为了节约篇幅，此处不再赘述。
在一些实施例中，金属掺杂氧化锌薄膜中的掺杂金属选自Mg 2+、Mn 2+中的至少一种。在一些实施例中，金属掺杂氧化锌薄膜中的掺杂金属选自Al 3+、Y 3+、La 3+、Li +、Gd 3+、Zr 4+、Ce 4+中的至少一种。掺杂金属离子的掺杂量参见上文，此处不再赘述。
在一些实施例中，电子传输层为第一电子传输层时，第一电子传输层即电子传输层的厚度为10～100nm。
在一种可能的实施方式中，电子传输层还包括第二电子传输层，且第二电子传输层为表面羟基量 小于或等于0.4的氧化锌薄膜。即电子传输层同时包括表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜和表面羟基量小于或等于0.4的氧化锌薄膜，两者沿着垂直于量子点发光层或阴极的方向层叠设置，即第二电子传输层设置在第一电子传输层靠近阴极或量子点发光层的一侧表面。在这种情况下，使用双层氧化锌电子传输时，其中，表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜，可以减少电子传输层向量子点发光层中注入的电子，使得量子点发光二极管器件在工作初期的电子注入效率较低，实现量子点发光二极管器件中载流子的注入平衡，器件处于载流子相同平衡的状态，因而具有较高的外量子效率；而量子点发光二极管器件在持续工作到稳定状态时，由于低表面羟基量的氧化锌薄膜的存在，使得量子点发光层带负电的状态依然会发生，并且达到动态平衡，进而使得最终电子注入效率处于较低的水平，与空穴注入效率构成载流子注入平衡，因此得到的量子点发光二极管器件寿命也会有的改善。
第一电子传输层和第二电子传输层层叠设置，两者的相对位置可以灵活设置。在一些实施例中，第二电子传输层设置在第一电子传输层靠近量子点发光层的一侧表面。在这种情况下，表面羟基量较少的氧化锌溶液沉积在量子点发光层上时，有利于得到更加平整的氧化锌薄膜。在一些实施例中，第二电子传输层也可以设置在第一电子传输层靠近量子点发光层的一侧表面。
在一些实施例中，第一电子传输层和第二电子传输层均为未掺杂氧化锌薄膜。即第一电子传输层和第二电子传输层由氧化锌制成，氧化锌中不含有掺杂金属，但第一电子传输层的氧化锌表面含有碳原子数为8-18的胺基配体和/或羧基配体。在一些实施例中，电子传输层由表面含有碳原子数为8-18的胺基配体和/或羧基配体的第一电子传输层和表面羟基量小于或等于0.4的第二电子传输层组成。示例性的，电子传输层还包括第二电子传输层，且第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜，第一电子传输层和第二电子传输层均为未掺杂氧化锌薄膜，且第二电子传输层设置在邻近量子点发光层的一侧表面。
在一些实施例中，第一电子传输层和第二电子传输层中的至少一层中的氧化锌为金属掺杂氧化锌。
在一些实施例中，表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜即第一电子传输层中的氧化锌为金属掺杂氧化锌，表面羟基量小于或等于0.4的氧化锌薄膜即第二电子传输层为未掺杂氧化锌薄膜。在这种情况下，如上文，一方面，表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜即第一电子传输层可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管器件。另一方面，具有低表面羟基量的氧化锌薄膜即第二电子传输层，使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命。此外，在碳原子数为8-18的胺基配体和/或羧基配体的氧化锌中掺杂金属离子，来实现有效的载流子注入调控，器件工作初期可以得到比未掺杂氧化锌薄膜作为电子传输层的量子点发光二极管器件更高的EQE，加之第一电子传输层的碳原子数为8-18的胺基配体和/或羧基配体的作用，两者协同，可以更有效地提高量子点发光二极管器件的EQE。本实施例通过调控氧化锌薄膜表面羟基量即可实现QLED器件的载流子注入平衡，无需改变器件结构(插入电子阻挡层)，也无需通过掺杂等手段对氧化锌薄膜进行改性，整个过程操作简单，成本低廉，具有良好的可重复性。
示例性的，电子传输层由表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜(第一电子传输层)和表面羟基量小于或等于0.4的未掺杂氧化锌薄膜(第二电子传输层)组成，且第一电子传输层中的氧化锌为金属掺杂氧化锌。在一些实施例中，电子传输层由表面含有碳原子数为8-18的胺基配体和/或羧基配体的金属掺杂氧化锌薄膜(第一电子传输层)和表面羟基量小于或等于0.4的未掺杂氧化锌薄膜(第二电子传输层)组成，且第二电子传输层设置在邻近量子点发光层的一侧表面。
在一些实施例中，表面含有碳原子数为8-18的胺基配体和/或羧基配体的第一电子传输层为未掺杂氧化锌薄膜，表面羟基量小于或等于0.4的氧化锌薄膜即第二电子传输层中的氧化锌为金属掺杂氧化锌。在这种情况下，一方面，表面含有碳原子数为8-18的胺基配体和/或羧基配体的第一电子传输层可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管器件。另一方面，具有低表面羟基量的第二电子传输层，使得量子点 发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命。此外，在第二电子传输层的氧化锌中掺杂金属离子，来实现有效的载流子注入调控，器件工作初期可以得到比未掺杂氧化锌薄膜作为电子传输层的量子点发光二极管器件更高的EQE，加之第一电子传输层的碳原子数为8-18的胺基配体和/或羧基配体的作用，两者协同，可以更有效地提高量子点发光二极管器件的EQE。本实施例通过调控氧化锌薄膜表面羟基量即可实现QLED器件的载流子注入平衡，无需改变器件结构(插入电子阻挡层)，也无需通过掺杂等手段对氧化锌薄膜进行改性，整个过程操作简单，成本低廉，具有良好的可重复性。
示例性的，电子传输层由碳原子数为8-18的胺基配体和/或羧基配体的未掺杂氧化锌薄膜(第一电子传输层)和表面羟基量小于或等于0.4的氧化锌薄膜(第二电子传输层)组成，且第二电子传输层中的氧化锌为金属掺杂氧化锌。在一些实施例中，电子传输层由碳原子数为8-18的胺基配体和/或羧基配体的未掺杂氧化锌薄膜(第一电子传输层)和表面羟基量小于或等于0.4的氧化锌薄膜(第二电子传输层)组成，且第二电子传输层中的氧化锌为金属掺杂氧化锌，第二电子传输层设置在邻近量子点发光层的一侧表面。
在一些实施例中，表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜即第一电子传输层中的氧化锌为金属掺杂氧化锌，表面羟基量小于或等于0.4的的氧化锌薄膜即第二电子传输层中的氧化锌为金属掺杂氧化锌。在这种情况下，一方面，表面含有碳原子数为8-18的胺基配体和/或羧基配体的第一电子传输层可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管器件。另一方面，具有低表面羟基量的第二电子传输层，使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命。此外，在第一电子传输层和第二电子传输层的氧化锌中掺杂金属离子，来实现有效的载流子注入调控，器件工作初期可以得到比未掺杂氧化锌薄膜作为电子传输层的量子点发光二极管器件更高的EQE，加之第一电子传输层的碳原子数为8-18的胺基配体和/或羧基配体的协同作用，可以显著提高量子点发光二极管器件的EQE。本实施例通过调控氧化锌薄膜表面羟基量即可实现QLED器件的载流子注入平衡，无需改变器件结构(插入电子阻挡层)，也无需通过掺杂等手段对氧化锌薄膜进行改性，整个过程操作简单，成本低廉，具有良好的可重复性。
示例性的，电子传输层由表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜(第一电子传输层)和表面羟基量大于或等于0.6的氧化锌薄膜(第二电子传输层)组成，且第一电子传输层和第二电子传输层中的氧化锌均为金属掺杂氧化锌。在一些实施例中，电子传输层由表面含有碳原子数为8-18的胺基配体和/或羧基配体的金属掺杂氧化锌薄膜(第一电子传输层)和表面羟基量大于或等于0.6的金属掺杂氧化锌薄膜(第二电子传输层)组成，且第二电子传输层设置在邻近量子点发光层的一侧表面。
上述实施例的一种实施方式中，如图1所示，电子传输层50由第一电子传输层51和第二电子传输层52组成，且第二电子传输层52较第一电子传输层51更靠近量子点发光层40，即第一电子传输层51靠近阴极60。表面表面羟基量低的氧化锌胶体溶液沉积在量子点发光层上时，有利于得到更加平整的氧化锌薄膜。
在一些实施例中，电子传输层包括第二电子传输层，第二电子传输层设置在第一电子传输层靠近阴极或量子点发光层的一侧表面，且第二电子传输层为金属掺杂氧化锌薄膜。在这种情况下，表面含有碳原子数为8-18的胺基配体和/或羧基配体的第一电子传输层可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管器件。同时，金属掺杂氧化锌的能级匹配优化或者电子迁移率优化，进一步优化量子点发光二极管的外量子效率(EQE)。
在上述实施例中，当电子传输层为双层氧化锌薄膜，每层氧化锌薄膜的厚度为10～100nm。在这种情况下，氧化锌薄膜厚度合适，不容易被电子击穿，有利于保持电子传输层的注入性能、成膜质量及表面平整性。考虑到金属掺杂氧化锌薄膜，由于其电子迁移率较低，因此薄膜厚度不宜过厚。示例性的，金属掺杂氧化锌薄膜的厚度为10-30nm。表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌 薄膜的厚度为10-80nm。表面羟基量小于或等于0.4的氧化锌薄膜，由于其电子迁移率较高，因此薄膜厚度可以适当厚些。示例性的，表表面羟基量小于或等于0.4的厚度为20-60nm。
在上述实施例的一些实施例中，电子传输层包括n个由第一电子传输层和第二电子传输层组成的薄膜叠层单元，其中，n大于或等于2。电子传输层采用叠层方式，可能使得能级匹配更佳，使器件寿命提升幅度更大。在一些实施例中，n为大于或等于2且小于或等于9的整数。
在一种可能的实施方式中，电子传输层包括第二电子传输层和第三电子传输层。
在一些实施例中，第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜，第三电子传输层选自表面羟基量大于或等于0.6的氧化锌薄膜，且第二电子传输层结合在第一电子传输层的一侧表面，第三电子传输层结合在第二电子传输层背离第一电子传输层的一侧表面。在这种情况下，一层表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜和一层表面高羟基量的氧化锌薄膜，可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终使得量子点发光二极管在工作中初期具有较高外量子效率；而一层低羟基量的氧化锌薄膜，使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命。
在一些实施例中，第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜，第三电子传输层选自表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜，且第二电子传输层结合在第一电子传输层的一侧表面，第三电子传输层结合在第二电子传输层背离第一电子传输层的一侧表面。在这种情况下，两层表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜，可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终使得量子点发光二极管在工作中初期具有较高外量子效率；而一层低羟基量的氧化锌薄膜，使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命。
在一些实施例中，第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜，第三电子传输层选自金属掺杂氧化锌薄膜，且第二电子传输层结合在第一电子传输层的一侧表面，第三电子传输层结合在第二电子传输层背离第一电子传输层的一侧表面。在这种情况下，一层表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜和一层金属掺杂氧化锌薄膜，可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终使得量子点发光二极管在工作中初期具有较高外量子效率；而一层低羟基量的氧化锌薄膜，使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命。由此，得到的量子点发光二极管器件兼具良好的EQE和期间寿命。
在一些实施例中，第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜，第三电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜，且第一电子传输层设置在第二电子传输层和第三电子传输层的一侧表面。在这种情况下，一层表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜的氧化锌薄膜，可以减少量子点发光层中注入的电子，实现量子点发光二极管器件中载流子的注入平衡，最终使得量子点发光二极管在工作中初期具有较高外量子效率；而两层低羟基量的氧化锌薄膜，使得量子点发光二极管器件在持续工作到稳定状态时也能够达到载流子注入平衡状态，进而获得良好的器件寿命。此外，由于表面羟基量较少的氧化锌溶液沉积在量子点发光层上时，有利于得到更加平整的氧化锌薄膜。由此，得到的量子点发光二极管器件兼具良好的EQE和期间寿命。
示例性的，如图2所示，电子传输层50包括第一电子传输层51、第二电子传输层52和第三电子传输层53，其中，第一电子传输层51为表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜，第二电子传输层52为表面羟基量小于或等于0.4的氧化锌薄膜，第三电子传输层53为表面羟基量小于或等于0.4的氧化锌薄膜，第三电子传输层53设置在第一电子传输层51背离第二电子传输层52的一侧表面。
应当理解的是，电子传输层含有第二电子传输层和第三电子传输层的实施例中，表面羟基量小于或等于0.4的氧化锌薄膜中的氧化锌是未掺杂氧化锌，也可以是金属掺杂氧化锌；同样的，表面羟基量大于或等于0.6的氧化锌薄膜中的氧化锌可以是未掺杂氧化锌，也可以是金属掺杂氧化锌。
电子传输层含有第三电子传输层的实施例中，在一些实施例中，电子传输层的厚度为10～100nm。 由于表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜、表面羟基量大于等于0.6的氧化锌薄膜或者金属掺杂氧化锌薄膜，由于其电子迁移率较低，因此薄膜厚度相对较薄；表面羟基量小于等于0.4的氧化锌薄膜，由于其电子迁移率较高，因此薄膜厚度相对较厚。在一些实施例中，表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜的厚度为10-80nm。在一些实施例中，表面羟基量大于或等于0.6的氧化锌薄膜的厚度为10-30nm。在一些实施例中，金属掺杂氧化锌薄膜的厚度为10-30nm。各层厚度在此范围内，使得在这种情况下，氧化锌薄膜厚度合适，不容易被电子击穿，有利于保持电子传输层的注入性能、成膜质量及表面平整性。
电子传输层含有第二电子传输层，且第二电子传输层为金属掺杂氧化锌薄膜的实施例，以及电子传输层含有第二电子传输层和第三电子传输层，且第二电子传输层和/或第三电子传输层为金属掺杂氧化锌薄膜的实施例中，在一些实施例中，金属掺杂氧化锌薄膜中的掺杂金属的类型、掺杂金属带来的影响以及掺杂金属的掺杂含量如上文(电子传输层为第一电子传输层的情形)所述，为了节约篇幅，此处不再赘述。
在一些实施例中，金属掺杂氧化锌薄膜中的掺杂金属选自Mg 2+、Mn 2+中的至少一种。在一些实施例中，金属掺杂氧化锌薄膜中的掺杂金属选自Al 3+、Y 3+、La 3+、Li +、Gd 3+、Zr 4+、Ce 4+中的至少一种。掺杂金属离子的掺杂量参见上文，此处不再赘述。
在一种可能的实施方式中，本申请实施例提供的上述两种量子点发光二极管(一种为电子传输层包括第一电子传输层，且第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；第二种为电子传输层含有氧化锌，且至少部分氧化锌的表面含有碳原子数为8-18的胺基配体和/或羧基配体)如图3所示，量子点发光二极管包括相对设置的阳极10和阴极60，以及设置在阴极60和阳极10之间的量子点发光层40，电子传输层50设置在阴极60和量子点发光层40之间。
在一些实施例中，发光二极管还包括设置在阳极10和量子点发光层40之间的空穴功能层。其中，空穴功能层包括空穴传输层、空穴注入层和电子阻挡层中的至少一种。在一些实施例中，量子点发光二极管还包括设置在阴极60和电子传输层50之间的电子注入层。
在上述实施例中，发光二极管还可以包括衬底，阳极10或阴极60设置在衬底上。
本申请实施例提供的发光二极管分为正置发光二极管和倒置发光二极管。
在一种实施方式中，正置量子点发光二极管包括相对设置的阳极10和阴极60，设置在阳极10和阴极60之间的量子点发光层40，以及设置在阴极60和量子点发光层40之间的电子传输层50，且阳极10设置在衬底上。在一些实施例中，在阳极10和量子点发光层40之间设置空穴传输层30，进一步的，在阳极10和空穴传输层之间设置空穴注入层20；和/或，在阴极60和电子传输层50之间设置电子注入层。在一些正置发光二极管的实施例中，如图4所示，量子点发光二极管包括衬底100，设置在衬底100表面的阳极10，设置在阳极10表面的空穴注入层20，设置在空穴注入层20表面的空穴传输层，设置在空穴传输层表面的量子点发光层40，设置在量子点发光层40表面的电子传输层50和设置在电子传输层50表面的阴极60。
在一种实施方式中，倒置量子点发光二极管包括包括相对设置的阳极10和阴极60的叠层结构，设置在阳极10和阴极60之间的量子点发光层40，以及设置在阴极60和量子点发光层40之间的电子传输层50，且阴极60设置在衬底上。在一些实施例中，在阳极10和量子点发光层40之间设置空穴传输层30，进一步的，在阳极10和空穴传输层之间设置空穴注入层20；和/或，在阴极60和电子传输层50之间设置电子注入层。在一些倒置发光二极管的实施例中，如图5所示，量子点发光二极管包括衬底100，设置在衬底100表面的阴极60，设置在阴极60表面的电子传输层50，设置在电子传输层50表面的发光层40，设置在量子点发光层40表面的空穴传输层，设置在空穴传输层表面的空穴注入层20和设置在空穴注入层20表面的阳极10。
上述实施例中，衬底100可为刚性衬底或柔性衬底，具体可以选择玻璃、硅晶片、聚碳酸酯、聚甲基丙烯酸甲酯、聚对苯二甲酸乙二醇酯、聚萘二甲酸乙二醇酯、聚酰胺、聚醚砜，或上述材料中的至少两种形成的组合物，或至少两种上述材料形成的层叠结构。
在一些实施例中，空穴注入层20的材料可以选择聚(亚乙基二氧噻吩):聚苯乙烯磺酸盐 (PEDOT:PSS)、HTL-1、HTL-2中的至少一种，当然，也可以是其它具有高注入性能的空穴注入材料。
PEDOT:PSS的结构如下：
Figure PCTCN2021143433-appb-000002
HTL-1的结构如下：
Figure PCTCN2021143433-appb-000003
Figure PCTCN2021143433-appb-000004
HTL-2的结构如下：
Figure PCTCN2021143433-appb-000005
在一些实施例中，空穴传输层30的材料可以选择常规的空穴传输材料。示例性的，空穴传输层30的材料包括4,4'-N,N'-二咔唑基-联苯(CBP)、聚[(9,9'-二辛基芴-2,7-二基)-co-(4,4'-(N-(4-仲丁基苯基)二苯胺))](TFB)、聚(4-丁基苯基-二苯基胺)(聚-TPD)、4,4',4'-三(N-咔唑基)-三苯胺(TCTA)、聚(N-乙烯基咔唑)(PVK)及其衍生物中的至少一种，当然，空穴传输层30的材料也可以是其它具有高注入性能的空穴传输材料。
量子点发光层40中的量子点为红、绿、蓝三种中的一种量子点，还可以为黄光量子点。其中，量子点可以为含镉或者不含镉。在一些实施例中，量子点发光层40中的量子点可以为单核量子点或核壳结构量子点，量子点的核和壳化合物可以各自独立地选自CdS、CdSe、CdTe、ZnO、ZnS、ZnSe、ZnTe、GaAs、GaP、GaSb、HgS、HgSe、HgTe、InAs、InP、InSb、AlAs、AlP、CuInS、CuInSe、以及各种核壳结构量子点或合金结构量子点中的至少一种。由此形成的量子点发光层具有激发光谱宽并且连续分布，发射光谱稳定性高等特点。
本申请实施例中，电子传输层50的材料和厚度如上文，此处不再赘述。本申请实施例中，电子传输层的厚度为10～100nm。当电子传输层的厚度小于10nm时，膜层很容易被电子击穿，不易保证载流子的注入性能；当电子传输层的厚度大于100nm时，则会阻碍电子的注入，影响器件的电荷注入平衡。
底电极(结合在衬底100上的阳极10或结合在衬底上的阴极60)可以采用常见的底电极材料，在一些实施例中，底电极的材料包括氧化锌、氧化铟、氧化锡、氧化铟锡(ITO)、氧化铟锌(IZO)、氟掺 杂的氧化锡中的至少一种。
在一些实施例中，顶电极(远离衬底100的阳极10或阴极60)为透明氧化物、薄金属或者两者的结合。在一些实施例中，透明氧化物可以为ITO、IZO、AZO；在一些实施例中，薄金属可以为Ag、Al、Au、Mg、Ca、Yb、Ba或者它们的合金；在一些实施例中，顶电极也可以为O/M/O，其中M为Ag、Al、Au、Mg、Ca、Yb、Ba或者它们的合金，O为氧化物，包括但不限于ITO、IZO、AZO。
本申请实施例提供的量子点发光二极管，电子传输层含有氧化锌，且至少部分氧化锌的表面含有碳原子数为8-18的胺基配体和/或羧基配体。由于配位的碳原子数为8-18的胺基配体和/或羧基配体的链长较长，在空间位阻效应的作用下，增加了薄膜中氧化锌纳米颗粒之间的距离，进而降低了电子传输层的电子迁移率，抑制电子在电子传输层中的传输，降低电子在量子点发光二极管中的传输，从而减少量子点发光层中注入的电子，实现量子点发光二极管中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管。
本申请实施例提供的量子点发光二极管，可以通过多种方法制备获得。下面本申请提供三种制备上述量子点发光二极管的制备方法实施例。
在第一种实施方式中，本申请实施例提供一种量子点发光二极管的制备方法，量子点发光二极管包括相对设置的阳极和阴极，设置在阳极和阴极之间的量子点发光层，设置在量子点发光层和阴极之间的电子传输层，其中，电子传输层包括第一电子传输层，且第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；
其中，如图6所示，表面羟基量大于或等于0.6的氧化锌薄膜的制备方法，包括：
S11.将锌盐溶液与第一碱液混合反应，反应结束后向混合溶液中加入沉淀剂，收集沉淀物；采用反应溶剂对沉淀物进行清洗处理两次或两次以下后，将得到的白色沉淀物溶解，得到氧化锌胶体溶液；
S12.在待制备表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上形成氧化锌胶体溶液，去除溶剂，制得表面羟基量大于或等于0.6的氧化锌薄膜。
本申请实施例提供的量子点发光二极管的制备方法，利用溶液法制备氧化锌胶体溶液作为表面羟基量大于或等于0.6的氧化锌薄膜的成膜溶液。利用溶液法制备氧化锌胶体溶液的制备过程中，采用反应溶剂对得到的沉淀物进行清洗处理两次或两次以下，以得到表面羟基量大于或等于0.6的氧化锌。利用表面羟基量大于或等于0.6的氧化锌薄膜作为第一电子传输层，电子向量子点发光层的传输受到抑制，注入到量子点发光层中的电子减少，使得量子点发光二极管中的电子和空穴更加平衡，从而使得器件外量子效率得到提升。
本申请实施例中，量子点发光二极管的组成，特别是电子传输层的情形，如上文第一方面，为了节约篇幅，此处不再赘述。
上述步骤S11通过溶液法制备氧化锌胶体溶液，溶液法可以是醇解法、水解法等中的一种。溶液法制备氧化锌的基本流程为：将锌盐溶液与第一碱液混合，反应生成氢氧化物中间体如氢氧化锌；氢氧化物中间体发生缩聚反应逐步生成氧化锌纳米颗粒。
本申请实施例中，锌盐溶液为锌盐溶解在溶剂形成的盐溶液。其中，锌盐选择能够与第一碱液反应生成锌的氢氧化物的盐，包括但不局限于醋酸锌、硝酸锌、硫酸锌、氯化锌中的一种。溶剂选择对锌盐以及生成的氧化锌纳米颗粒均具有较好的溶解性的溶剂，包括但不局限于水、有机醇、有机醚、砜等极性较大的溶剂。在一些实施例中，溶剂选自水、有机醇、有机醚、砜中的至少一种。这类溶剂不仅对锌盐具有较好的溶解性，作为反应介质在碱性环境中比较稳定，不容易引入副反应；而且对具有极性的终产物氧化锌纳米颗粒具有溶解性。此外，上述溶剂能够使反应碱发生电离，可以同时作为锌盐的溶解溶剂和反应碱的稀释或溶解溶剂，促进碱与锌盐之间的反应。示例性的，溶剂可选择水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、二甲基亚砜(DMSO)中的至少一种。
本申请实施例中，第一碱液为能够与锌盐反应生成锌的氢氧化物的碱形成的溶液，具体的，第一碱液在反应体系中提供与锌离子反应的氢氧根离子。应当理解的是，当锌盐中含有掺杂金属离子时，第一碱液同时与锌离子和掺杂金属离子反应的氢氧根离子。本申请实施例中，采用溶剂溶解或稀释碱获得第一碱液。一方面，固体碱如氢氧化钠可以通过溶剂溶解形成液态第一碱液，再添加到反应体系中，有利 于第一碱液在反应体系中的分散均匀性；另一方面，通过溶解或稀释，可以调节第一碱液中碱的浓度，使其浓度在0.1-2mol/L，以避免加入的碱浓度太高，造成反应速率过快，最终导致得到的氧化锌纳米颗粒大小不均匀，且氧化锌颗粒过大时，也发生团聚。
其中，第一碱液中的碱，可以选择无机碱，也可以选择有机碱；可以选择强碱，也可以选择弱碱。在一种可能的实施方式中，第一碱液中的碱选自K b＞10 -1的碱，示例性的，K b＞10 -1的碱选自氢氧化钾、氢氧化钠、氢氧化锂中的至少一种。在一种可能的实施方式中，第一碱液中的碱选自K b＜10 -1的碱，示例性的，K b＜10 -1的碱选自TMAH、氨水、乙醇胺、乙二胺中的至少一种。用于溶解或稀释碱形成第一碱液的溶剂，能够溶解碱或与碱混溶，此外溶剂与氧化锌纳米颗粒极性相同。在一些实施例中，用于溶解或稀释碱形成第一碱液的溶剂可以与锌盐溶液中的溶剂相同，也可以与锌盐溶液中的溶剂不同。在一些实施例中，用于溶解或稀释碱形成第一碱液的溶剂选择与锌盐溶液相同的溶剂，更有利于获得稳定的反应体系。其中，相同的溶剂包括但不局限于水、有机醇、有机醚、砜等极性较大的溶剂。在一些实施例中，溶剂选自水、有机醇、有机醚、砜中的至少一种。示例性的，溶剂可选择水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、二甲基亚砜(DMSO)中的至少一种。
在一些实施例中，在温度为0～70℃的条件下，将锌盐溶液与第一碱液混合处理，反应30min～4h，以制备氧化锌纳米颗粒。在一些实施例中，锌盐溶液与第一碱液混合处理的方式为：在室温(5℃～40℃)下溶解锌盐获得锌盐溶液，在室温下溶解或稀释碱获得第一碱液；将锌盐溶液的温度调整至0～70℃，加入第一碱液。在这种情况下，加入的碱与锌盐溶液中的锌盐反应，生成氧化锌纳米颗粒，并能获得良好的颗粒分散性。当反应温度低于0℃时，会显著减缓氧化锌纳米颗粒的生成，且反应需要借助特殊设备才能实现，增加了反应难度，甚至在一些条件下不易生成氧化锌纳米颗粒，而只能得到氢氧化物中间体；而当反应温度高于70℃时，反应活性过高，生成的氧化锌纳米颗粒团聚严重，不易得到分散性良好的胶体溶液，影响氧化锌胶体溶液的后期成膜。在一些实施例中，锌盐溶液与第一碱液的反应温度为室温～50℃，在这种情况下，不仅有利于氧化锌纳米颗粒的形成，而且得到的氧化锌离子具有较好的颗粒分散性，有利于氧化锌胶体溶液的成膜。在一些实施例中，在温度为0～30℃的条件下，将锌盐溶液与第一碱液混合处理，可以轻松生成合格的氧化锌胶体溶液；在一些实施例中，在温度为30℃～70℃的条件下，也可以生成氧化锌胶体溶液，得到的氧化锌胶体溶液品质不如0～30℃的条件下生成的氧化锌胶体溶液，同时反应时间也要减少。在一些实施例中，将锌盐溶液与第一碱液混合处理的步骤中，按照氢氧根离子与锌离子的摩尔比为1.5:1～2.5:1的比例，将锌盐溶液与第一碱液混合处理，以确保氧化锌纳米颗粒的形成，并减少反应副产物的生成。当氢氧根离子与锌离子的摩尔比小于1.5：1时，锌盐显著过量，导致大量锌盐不易生成氧化锌纳米颗粒；而当氢氧根离子与锌离子的摩尔比大于2.5：1时，第一碱液显著过量，过量的氢氧根离子与氢氧化锌中间体形成稳定的络合物，不易缩聚生成氧化锌纳米颗粒。在一些实施例中，将锌盐溶液与第一碱液混合处理的步骤中，锌盐溶液与第一碱液的添加量满足：第一碱液提供的氢氧根离子的摩尔量与锌盐提供的锌离子的摩尔量之比为1.7:1～1.9:1。
在一些实施例中，将锌盐溶液与第一碱液混合后，在0～70℃的反应温度下反应30min～4h以确保氧化锌纳米颗粒的形成，并控制纳米粒子的粒径。当反应时间少于30min时，过低的反应时间反应得到的是氧化锌的团簇种子，此时样品的结晶状态不完整，晶体结构较差，如果将其用作电子传输层材料的话，会使得电子传输层的导电性很差；而当反应时间超过4h时，过长的颗粒长大时间使生成的纳米粒子过大并且粒径不均匀，氧化锌胶体溶液成膜后表面粗糙度会较高，影响电子的传输性能。在一些实施例中，将锌盐溶液与第一碱液混合后，在反应温度下反应1～2h。
在一些实施例中，在温度为0～70℃的条件下，将锌盐溶液与第一碱液混合，反应30min～4h，在搅拌的条件下进行，以促进反应的均匀性和得到的氧化锌纳米颗粒的颗粒均匀性，得到尺寸均匀的氧化锌纳米颗粒。
本申请实施例中，反应结束后，向反应结束后的混合溶液中加入沉淀剂，收集沉淀物。沉淀剂选择与终产物氧化锌纳米颗粒极性相反的溶剂，从而通过降低氧化锌纳米颗粒的溶解性，将其沉淀下来。在一些实施例中，沉淀剂选择极性较弱的溶剂，这类沉淀剂与氧化锌纳米颗粒的极性相反，有利于氧化锌纳米颗粒的沉淀。示例性的，沉淀剂包括但不局限于乙酸乙酯、丙酮、正己烷、正庚烷，以及其余低极 性的长链烷烃等。
在一些实施例中，向反应结束后的混合溶液中加入2～6倍体积的沉淀剂(即：沉淀剂与混合溶液的体积比为2:1～6:1)，混合溶液中产生白色沉淀。在这种情况下，确保在充分沉淀氧化锌纳米颗粒的前提下，不会因为沉淀剂过多导致氧化锌粒子溶解性受到破坏的情况。在一些实施例中，沉淀剂与混合溶液的体积比为3:1～5:1。
本申请实施例中，将经沉淀处理的混合体系进行离心处理，收集沉淀物。本申请实施例采用反应溶剂对收集到的沉淀物进行清洗处理，以去除没有参与反应的反应物。采用反应溶剂对得到的氧化锌纳米颗粒进行清洗，能够将制备氧化锌纳米颗粒的多余锌盐、碱等原料去除，以提高氧化锌纳米颗粒的纯度。应当注意的是，反应溶剂如上文所述。在一些实施例中，反应溶剂选自水、有机醇、有机醚、砜中的至少一种。示例性的，反应溶剂选自水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。
由于本申请实施例采用锌盐与碱反应形成氧化锌纳米颗粒，极性的氧化锌溶液中，由于氧化锌胶体自身所具有的特性，其表面吸附有大量的电离羟基基团。这些羟基基团带负电，大量吸附在氧化锌纳米颗粒表面，使得氧化锌纳米颗粒的表面也带有了负电。在氧化锌纳米颗粒之间静电库伦斥力的作用下，氧化锌纳米颗粒得以分散在极性溶液中，并具有较好的溶液稳定性和分散性。当把这种氧化锌胶体溶液沉积成氧化锌薄膜后，大量的羟基基团依然会包覆在固化成膜后的氧化锌颗粒的表面。当这种氧化锌薄膜被用做量子点发光二极管结构中的电子传输层时，由于氧化锌表面吸附有大量带负电的羟基基团，会对电子在氧化锌层中的传输起到一定的抑制和阻碍作用，因此氧化锌薄膜表面羟基量的多少会直接影响到量子点发光二极管器件中电子的注入情况。当表面羟基量较多时，电子在量子点发光二极管器件中的传输会受到抑制，量子点发光层中注入的电子将减少；而当表面羟基量较少时，电子在量子点发光二极管器件中的传输将通畅，量子点发光层中注入的电子将增多。因此，本申请实施例通过控制清洗次数，来调节得到的氧化锌纳米颗粒的表面羟基量。
具体的，当对氧化锌纳米颗粒的清洗次数较多时，其表面残留的羟基量就相应较少；当氧化锌纳米颗粒的清洗次数较多时，其表面残留的羟基量就相应较少。本申请实施例采用反应溶剂对沉淀物进行清洗处理两次或两次以下，使其表面羟基量大于或等于0.6。
在一种可能的实施方式中，若第一碱液中的碱为K b＞10 -1的碱，清洗处理的次数小于或等于2次。在这种情况下，由于K b＞10 -1的碱的电离系数较大，使得最终合成的氧化锌胶体表面的羟基量较多，清洗次数小于或等于2次后能保持氧化锌表面高羟基量的状态。
在一种可能的实施方式中，若第一碱液中的碱为K b＜10 -1的碱，清洗处理的次数小于或等于1次。当反应碱为K b＜10 -1的碱时，由于碱的电离系数较小，使得最终合成的氧化锌胶体表面的羟基量较少，因此清洗次数小于或等于1次才可实现表面较多羟基量。
其中，不同K b碱的选择，可参照上文记载。示例性的，K b＞10 -1的碱包括但不限于氢氧化钾、氢氧化钠、氢氧化锂等无机强碱；K b＜10 -1的碱包括但不限于TMAH、氨水、乙醇胺、乙二胺等有机弱碱。
在一些实施例中，第一碱液中的碱选自氢氧化钾、氢氧化钠、氢氧化锂中的至少一种，采用反应溶剂对收集到的沉淀物进行清洗处理的次数为1次，能够得到表面羟基量大于或等于0.6的氧化锌纳米颗粒；在一些实施例中，第一碱液中的碱选自TMAH、氨水、乙醇胺、乙二胺中的至少一种，采用反应溶剂对收集到的沉淀物进行清洗处理的次数为1次，能够得到表面羟基量大于或等于0.6的氧化锌纳米颗粒。
清洗处理后得到白色沉淀物，将得到的白色沉淀物溶解，得到氧化锌胶体溶液。
在一种可能的实施方式中，表面羟基量大于或等于0.6的氧化锌薄膜为金属掺杂氧化锌薄膜，对应的，表面羟基量大于或等于0.6的氧化锌为金属掺杂氧化锌，此时，锌盐溶液中还含有掺杂金属离子。
金属掺杂氧化锌薄膜中的掺杂金属的类型、掺杂金属带来的影响以及掺杂金属的掺杂含量如上文(电子传输层为第一电子传输层的情形)所述，为了节约篇幅，此处不再赘述。
在一些实施例中，金属掺杂氧化锌薄膜中的掺杂金属选自Mg 2+、Mn 2+中的至少一种。在一些实施例中，金属掺杂氧化锌薄膜中的掺杂金属选自Al 3+、Y 3+、La 3+、Li +、Gd 3+、Zr 4+、Ce 4+中的至少一种。 掺杂金属离子的掺杂量参见上文，此处不再赘述。
在一些实施例中，锌盐溶液中含有锌离子和掺杂金属离子，且在锌盐溶液与第一碱液混合的步骤中，锌盐溶液与第一碱液的添加量满足：金属离子的摩尔量与化合价数的乘积与氢氧根离子的摩尔量之比为0.75：1～1.25:1。在一些实施例中，将锌盐溶液与第一碱液混合处理的步骤中，锌盐溶液与第一碱液的添加量满足金属离子的摩尔量与化合价数的乘积与氢氧根离子的摩尔量之比为0.85:1～0.95:1。
上述步骤S12中，可以根据制备的量子点发光二极管器件的类型，在待制备表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上形成上述氧化锌胶体溶液，去除溶剂，制得表面羟基量大于或等于0.6的氧化锌薄膜。
在一些实施例中，在预制器件基板上形成上述氧化锌胶体溶液，可以采用包括但不局限于旋涂法、刮涂法、印刷法、喷涂法、滚涂法、电沉积法等中的一种。在预制器件基板上形成上述氧化锌胶体溶液后，通过退火处理去除溶剂，得到表面羟基量大于或等于0.6的氧化锌薄膜。
在一种可能的实施方式中，量子点发光二极管为正置量子点发光二极管，预制器件基板包括阳极基板，结合在阳极基板上的量子点发光层。在一些实施例中，预制器件基板还包括设置在阳极基板和量子点发光层之间的空穴功能层。其中，空穴功能层包括空穴传输层、空穴注入层和电子阻挡层中的至少一种。
在一种可能的实施方式中，量子点发光二极管为倒置量子点发光二极管，预制器件基板为阴极基板。在一些实施例中，预制器件基板还包括结合在阴极基板的阴极表面的电子注入层。
在一些实施例中，表面羟基量大于或等于0.6的氧化锌薄膜可以单独作为电子传输层。
在一些实施例中，电子传输层包括两层氧化锌薄膜或包括n个由两层氧化锌薄膜组成的薄膜叠层单元，两层氧化锌薄膜分别命名为第一电子传输层和第二电子传输层，n大于或等于2。在一些实施例中，n为大于或等于2且小于或等于9的整数。其中，至少第一电子传输层为上述方法制备的表面羟基量大于或等于0.6的氧化锌薄膜，第二电子传输层的情形，可以参考上文量子点发光二极管器件第二电子传输层中的情形。
在一些实施例中，第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜，或第二电子传输层为金属掺杂氧化锌薄膜。其中，第一电子传输层可以设置在邻近量子点发光层的一侧，也可以设置在邻近阴极的一侧。优选的，第二电子传输层设置在邻近量子点发光层的一侧或金属掺杂氧化锌薄膜设置在邻近量子点发光层的一侧，可以得到更加平整的氧化锌薄膜。
在一些实施例中，电子传输层包括三层氧化锌薄膜，三层氧化锌薄膜分别命名为第一电子传输层、第二电子传输层和第三电子传输层。其中，至少第一电子传输层为上述方法制备的表面羟基量大于或等于0.6的氧化锌薄膜，第二电子传输层和第三电子传输层的情形，可以参考上文量子点发光二极管器件中电子传输层包含第三电子传输层的情形。
上述实施例中，表面羟基量小于或等于0.4的氧化锌薄膜，可以通过表面羟基量小于或等于0.4的氧化锌胶体溶液形成。
上述实施例中，金属掺杂氧化锌薄膜，可以按照下述方法制备获得：
在温度为0～70℃的条件下，将含有掺杂金属离子的锌盐溶液与第一碱液混合，反应30min～4h；向反应结束后的混合溶液中加入沉淀剂，收集沉淀物；采用反应溶剂对沉淀物进行清洗处理后，将得到的白色沉淀物溶解，得到掺杂金属氧化锌胶体溶液；将掺杂掺杂金属氧化锌胶体溶液形成在待制备金属掺杂氧化锌薄膜的基板上，制得金属掺杂氧化锌薄膜。该实施例中，锌盐溶液的锌盐和溶剂类型以及锌盐溶液的含量、掺杂离子的类型和掺杂含量、第一碱液的类型和添加量、反应温度和反应时间、沉淀剂的选择和添加量，均参照本申请实施例上述步骤S11进行。该方法中，含有掺杂金属离子的锌盐溶液可以通过将锌盐和选定的金属盐按一定比例在室温下溶解在溶剂中获得。将含有掺杂金属离子的锌盐溶液与第一碱液混合的步骤中，碱的添加量满足：金属离子的摩尔量与化合价数的乘积与氢氧根离子的摩尔量之比为0.75：1～1.25:1。
在第二种实施方式中，本申请实施例提供一种量子点发光二极管的制备方法，量子点发光二极管包括相对设置的阳极和阴极，设置在阳极和阴极之间的量子点发光层，设置在量子点发光层和阴极之间 的电子传输层，其中，电子传输层包括第一电子传输层，且第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；
其中，如图7所示，表面羟基量大于或等于0.6的氧化锌薄膜的制备方法，包括：
S21.将锌盐溶液与第一碱液反应，制备氧化锌纳米颗粒；将氧化锌纳米颗粒溶解，得到氧化锌胶体溶液；向氧化锌胶体溶液加入第二碱液，调节氧化锌胶体溶液的pH大于或等于8，得到氧化锌溶液；
S22.在待制备表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上形成氧化锌胶体溶液，去除溶剂，制得表面羟基量大于或等于0.6的氧化锌薄膜。
本申请实施例提供的量子点发光二极管的制备方法，先利用溶液法制备氧化锌胶体溶液，然后向氧化锌胶体溶液加入第二碱液，调节氧化锌胶体溶液的pH大于或等于8，得到氧化锌溶液，以得到表面羟基量大于或等于0.6的氧化锌。利用表面羟基量大于或等于0.6的氧化锌薄膜作为第一电子传输层，电子向量子点发光层的传输受到抑制，注入到量子点发光层中的电子减少，使得量子点发光二极管中的空穴电子注入更加平衡，最终使得器件寿命得到提升。
本申请实施例中，量子点发光二极管的组成，特别是电子传输层的情形，如上文第一方面，为了节约篇幅，此处不再赘述。
上述步骤S21通过溶液法制备氧化锌胶体溶液的方法，锌盐溶液、锌盐溶液中的锌盐及溶剂的选择依据、类型，以及锌盐溶液的形成方式，第一碱液、第一碱液中的碱及溶剂的选择依据、类型，以及第一碱液的形成方式，如上述第一种实施方式步骤S11所述，为了节约篇幅，此处不再赘述。将锌盐溶液与第一碱液混合反应的反应条件和时间，锌盐溶液与第一碱液的含量比例，以及优选情形等，如上述第一种实施方式步骤S11所述，为了节约篇幅，此处不再赘述。
在一些实施例中，反应结束后，向反应结束后的混合溶液中加入沉淀剂，收集沉淀物。沉淀剂的选择参见上述第一种实施方式。
本申请实施例中，将经沉淀处理的混合体系进行离心处理，收集沉淀物。离心处理的方法和条件参见上述第一种实施方式。
将经清洗处理后的沉淀物进行溶解，得到氧化锌胶体溶液。
本申请实施例中，向氧化锌胶体溶液加入第二碱液，调节氧化锌胶体溶液的pH大于或等于8。氧化锌表面的羟基配体与氧化锌胶体溶液中电离状态的羟基构成了动态的平衡，而上述第二碱液的加入则会打破这一平衡。具体的，加入第二碱液后，由于氧化锌胶体溶液中的电离状态的羟基量增加，进而使得氧化锌表面羟基配体的量也会相应增加。但同时，第二碱液中碱的加入量也不能过多(pH值不能过大)，否则会使得氧化锌颗粒反应为氢氧化锌，降低氧化锌胶体溶液的浓度。因此，在一些实施例中，通过加第二碱液调节氧化锌胶体溶液的pH为9～12之间，在使得得到的氧化锌表面羟基量大于或等于0.6的基础上，还能使得氧化锌纳米颗粒具有较高的产率(浓度)。在一些实施例中，通过加第二碱液调节氧化锌胶体溶液的pH为9～10之间。
本申请实施例中，第二碱液中的碱可以选择无机碱，也可以选择有机碱；可以选择强碱，也可以选择弱碱。在一些实施例中，第二碱液选自氢氧化钾、氢氧化钠、氢氧化锂、TMAH、氨水、乙醇胺、乙二胺中的至少一种形成的第二碱液。本申请实施例中，第二碱液为无机碱溶解形成的溶液或有机碱经溶解或稀释后形成的溶液。通过对碱进行溶解或稀释，对第二碱液浓度进行调整，从而控制反应速率，从而使氧化锌纳米颗粒表面羟基的调整能够充分进行。其中，用于溶解或稀释酸形成第二碱液的溶剂，能够溶解碱或与碱混溶，此外溶剂与氧化锌纳米颗粒极性相同。在一些实施例中，用于溶解或稀释碱形成第二碱液的可以与锌盐溶液中的溶剂相同，也可以与锌盐溶液中的溶剂不同。在一些实施例中，用于溶解或稀释碱形成第二碱液的溶剂溶剂包括但不局限于水、有机醇、有机醚、砜等极性较大的溶剂。在一些实施例中，溶剂选自水、有机醇、有机醚、砜中的至少一种。示例性的，溶剂可选择水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、二甲基亚砜(DMSO)中的至少一种。
在一种可能的实施方式中，表面羟基量大于或等于0.6的氧化锌薄膜为金属掺杂氧化锌薄膜，对应的，表面羟基量大于或等于0.6的氧化锌为金属掺杂氧化锌，此时，锌盐溶液中还含有掺杂金属离子。该实施例中，掺杂金属离子的选择，如上文金属掺杂氧化锌薄膜中的掺杂金属的选择。
在一些实施例中，锌盐溶液中含有锌离子和掺杂金属离子，且在锌盐溶液与第一碱液混合的步骤中，锌盐溶液与第一碱液的添加量满足：金属离子的摩尔量与化合价数的乘积与氢氧根离子的摩尔量之比为0.75：1～1.25:1。在一些实施例中，将锌盐溶液与第一碱液混合处理的步骤中，锌盐溶液与第一碱液的添加量满足金属离子的摩尔量与化合价数的乘积与氢氧根离子的摩尔量之比为0.85:1～0.95:1。
上述步骤S22中，可以根据制备的量子点发光二极管器件的类型，在待制备表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上形成上述氧化锌溶液，去除溶剂，制得表面羟基量大于或等于0.6的氧化锌薄膜。
步骤S22的实施方式参照上述第一种实施方式。
在第三种实施方式中，本申请实施例提供一种量子点发光二极管的制备方法，量子点发光二极管包括相对设置的阳极和阴极，设置在阳极和阴极之间的量子点发光层，设置在量子点发光层和阴极之间的电子传输层，其中，电子传输层包括第一电子传输层，且第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；
其中，如图8所示，表面羟基量大于或等于0.6的氧化锌薄膜的制备方法，包括：
S31.在待制备表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上制备氧化锌预制薄膜；
S32.在氧化锌预制薄膜的表面沉积第二碱液后进行干燥处理，得到氧化锌薄膜。
本申请实施例提供的量子点发光二极管的制备方法，对氧化锌预制薄膜进行碱处理，氧化锌薄膜表面会形成液态膜，使得氧化锌预制薄膜表面的羟基量会与液态膜中的碱含量构成动态平衡，进而增加氧化锌预制薄膜表面的羟基量，以得到表面羟基量大于或等于0.6的氧化锌。在这种情况下，利用表面羟基量大于或等于0.6的氧化锌薄膜作为第一电子传输层，电子向量子点发光层的传输受到抑制，注入到量子点发光层中的电子减少，使得量子点发光二极管中的空穴电子注入更加平衡，最终使得器件寿命得到提升。
本申请实施例中，量子点发光二极管的组成，特别是电子传输层的情形，如上文第一方面，为了节约篇幅，此处不再赘述。
上述步骤S31中，氧化锌预制薄膜可以通过多种方式制备获得，示例性的，通过溶液法或溶胶凝胶法制备氧化锌预制薄膜。
在一些实施例中，氧化锌预制薄膜通过溶液法制备获得，包括：将锌盐溶液与第一碱液混合反应，制备氧化锌纳米颗粒；将氧化锌纳米颗粒溶解，得到氧化锌胶体溶液；在待制备表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上形成氧化锌胶体溶液，去除溶剂，制得氧化锌预制薄膜。
其中，将锌盐溶液与第一碱液混合反应，制备氧化锌纳米颗粒的步骤，参照上述第一种实施方式中的步骤S11，为了节约篇幅，此处不再赘述。
在一种可能的实施方式中，表面羟基量小于或等于0.4的氧化锌薄膜薄膜中的氧化锌为金属掺杂氧化锌，对应的，表面羟基量小于或等于0.4的氧化锌薄膜薄膜中的氧化锌为金属掺杂氧化锌，此时，锌盐溶液中还含有掺杂金属离子。该实施例中，掺杂金属离子的选择以及掺杂含量，如上文金属掺杂氧化锌薄膜中的掺杂金属的选择。
本申请实施例中，可以根据制备的量子点发光二极管器件的类型，在待制备表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上形成上述氧化锌胶体溶液，去除溶剂，制得表面羟基量大于或等于0.6的氧化锌薄膜。
在一些实施例中，在预制器件基板上形成上述氧化锌胶体溶液，参照上述步骤S12“在待制备所述表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上形成所述氧化锌胶体溶液，去除溶剂，制得表面羟基量大于或等于0.6的氧化锌薄膜”的步骤。
上述步骤S32中，通过在氧化锌预制薄膜上沉积第二碱液，来改变氧化锌预制薄膜表面的羟基量。具体的，当沉积第二碱液后，氧化锌预制薄膜表面会形成液态膜，因此氧化锌预制薄膜表面的羟基会与液态膜中的碱含量构成动态平衡，进而增加氧化锌预制薄膜表面的羟基量。
本申请实施例中，第二碱液中的碱可以选择无机碱，也可以选择有机碱；可以选择强碱，也可以选择弱碱。在一些实施例中，第二碱液选自氢氧化钾、氢氧化钠、氢氧化锂、TMAH、氨水、乙醇胺、乙 二胺中的至少一种形成的第二碱液。本申请实施例中，第二碱液为无机碱溶解形成的溶液或有机碱经溶解或稀释后形成的溶液。通过对碱进行溶解或稀释，对第二碱液浓度进行调整，从而控制反应速率，从而使氧化锌纳米颗粒表面羟基的调整能够充分进行。其中，用于溶解或稀释酸形成第二碱液的溶剂，能够溶解碱或与碱混溶，此外溶剂与氧化锌纳米颗粒极性相同。在一些实施例中，用于溶解或稀释碱形成第二碱液的可以与锌盐溶液中的溶剂相同，也可以与锌盐溶液中的溶剂不同。在一些实施例中，用于溶解或稀释碱形成第二碱液的溶剂溶剂包括但不局限于水、有机醇、有机醚、砜等极性较大的溶剂。在一些实施例中，溶剂选自水、有机醇、有机醚、砜中的至少一种。示例性的，溶剂可选择水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、二甲基亚砜(DMSO)中的至少一种。
本申请实施例中，需要对碱溶液的浓度和添加量进行控制。这是因为：当碱的浓度和添加量过大时，会使得氧化锌预制薄膜的表面产生大量的氢氧化锌杂质，影响氧化锌薄膜的质量；而当碱的浓度和添加量过小时，又不易起到增加氧化锌表面羟基量的作用。在一些实施例中，第二碱液的浓度为0.05-0.5mmol/L，以获得合适的浓度对氧化锌预制薄膜的表面羟基量进行调控。在一些实施例中，第二碱液的沉积量与下层氧化锌预制薄膜的重量满足：每5mg氧化锌预制薄膜，使用50μL-1000μL的第二碱液进行处理。第二碱液的浓度和碱添加量过大，都会使得氧化锌预制薄膜的表面产生大量的氢氧化锌杂质，影响氧化锌薄膜的质量；而第二碱液的浓度和碱添加量过小时，又不易起到增加氧化锌表面羟基量的作用。应当理解的是，第二碱液的浓度可根据所选择的碱的不同类型进行灵活调节。
无机碱一般为强碱，氢氧根离子电离能力较强，所以只需低浓度少量无机碱即可调节氧化锌表面羟基量。而有机碱一般为弱碱，氢氧根离子电离能力较弱，因此需要相对而言的高浓度大量有机碱才能有效调节氧化锌表面羟基量。
在一些实施方式中，第二碱液中的碱为无机碱，第二碱液的浓度为0.05-0.1mmol/L。示例性的，无机碱选自氢氧化钾、氢氧化钠、氢氧化锂中的至少一种。在这种情况下，第二碱液的沉积量与下层氧化锌预制薄膜的重量满足：每5mg氧化锌预制薄膜，使用50μL-400μL的第二碱液进行处理。
在一些实施方式中，第二碱液中的碱为有机碱，此时，对应形成的第二碱液的浓度为0.2-0.4mmol/L。示例性的，有机羧酸选自TMAH、氨水、乙醇胺、乙二胺中的至少一种。在这种情况下，第二碱液的沉积量与下层氧化锌预制薄膜的重量满足：每5mg氧化锌预制薄膜，使用500μL-1000μL的第二碱液进行处理。
本申请实施例中，在氧化锌预制薄膜的表面沉积第二碱液的方法可以采用溶液加工法，包括但不限于旋涂法、刮涂法、印刷法、喷涂法、滚涂法、电沉积法等中的一种。
在氧化锌预制薄膜的表面沉积第二碱液后，进行干燥处理，通过干燥处理使第二碱液中的电离氢离子与氧化锌表面的羟基充分反应。在一些实施例中，干燥处理的温度为10℃～100℃，干燥时间为10分钟～2小时。在这种情况下，第二碱液中的电离氢离子与氧化锌表面的羟基充分反应，以增加氧化锌表面的羟基量。若干燥温度过高或干燥处理的时间过长，会导致第二碱液迅速烘干，氧化锌预制薄膜迅速变成固体膜，进而使得第二碱液中的电离氢离子与氧化锌表面的羟基不易进行充分的反应，不易充分降低氧化锌表面的羟基量；而当干燥温度过低或干燥处理的时间过短时，会导致氧化锌预制薄膜较难充分干燥，影响下一层的制备，特别是影响电极的蒸镀质量。在一些实施例中，干燥处理的温度为10℃～50℃，干燥时间为30分钟～2小时。通过该方法改变氧化锌表面的羟基量，最终得到的薄膜表面可能会保留有极少量的碱形成的辅助层。
在一种可能的实施方式中，量子点发光二极管为正置量子点发光二极管，预制器件基板包括阳极基板，结合在阳极基板上的量子点发光层。在一些实施例中，预制器件基板还包括设置在阳极基板和量子点发光层之间的空穴功能层。其中，空穴功能层包括空穴传输层、空穴注入层和电子阻挡层中的至少一种。
在一种可能的实施方式中，量子点发光二极管为倒置量子点发光二极管，预制器件基板为阴极基板。在一些实施例中，预制器件基板还包括结合在阴极基板的阴极表面的电子注入层。
在一些实施例中，表面羟基量大于或等于0.6的氧化锌薄膜可以单独作为电子传输层。
在一些实施例中，电子传输层包括两层氧化锌薄膜或包括n个由两层氧化锌薄膜组成的薄膜叠层单 元，两层氧化锌薄膜分别命名为第一电子传输层和第二电子传输层，n大于或等于2。在一些实施例中，n为大于或等于2且小于或等于9的整数。其中，至少第一电子传输层为上述方法制备的表面羟基量大于或等于0.6的氧化锌薄膜，第二电子传输层的情形，可以参考上文量子点发光二极管器件第二电子传输层中的情形。
在一些实施例中，第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜，或第二电子传输层为金属掺杂氧化锌薄膜。其中，第一电子传输层可以设置在邻近量子点发光层的一侧，也可以设置在邻近阴极的一侧。优选的，表面羟基量小于或等于0.4的氧化锌薄膜或金属掺杂氧化锌薄膜设置在邻近量子点发光层的一侧，可以得到更加平整的氧化锌薄膜。
在一些实施例中，电子传输层包括三层氧化锌薄膜，三层氧化锌薄膜分别命名为第一电子传输层、第二电子传输层和第三电子传输层。其中，至少第一电子传输层为上述方法制备的表面羟基量大于或等于0.6的氧化锌薄膜，第二电子传输层和第三电子传输层的情形，可以参考上文量子点发光二极管器件中电子传输层包含第三电子传输层的情形。
上述实施例中，表面羟基量小于或等于0.4的氧化锌薄膜，可以通过表面羟基量小于或等于0.4的氧化锌胶体溶液形成。
上述实施例中，金属掺杂氧化锌薄膜，可以参照第一种实施方法提供的金属掺杂氧化锌薄膜的方法制得。在一些实施例中，金属掺杂氧化锌薄膜的制备，包括：
在温度为0～70℃的条件下，将含有掺杂金属离子的锌盐溶液与第一碱液混合，反应30min～4h；向反应结束后的混合溶液中加入沉淀剂，收集沉淀物；采用反应溶剂对沉淀物进行清洗处理后，将得到的白色沉淀物溶解，得到掺杂金属氧化锌胶体溶液；将掺杂掺杂金属氧化锌胶体溶液形成在待制备金属掺杂氧化锌薄膜的基板上，制得金属掺杂氧化锌薄膜。该实施例中，锌盐溶液的锌盐和溶剂类型以及锌盐溶液的含量、掺杂离子的类型和掺杂含量、第一碱液的类型和添加量、反应温度和反应时间、沉淀剂的选择和添加量，掺杂金属离子的类型以及含量，均参照本申请实施例上述步骤S11进行。在一些实施例中，将含有掺杂金属离子的锌盐溶液与第一碱液混合的步骤中，碱的添加量满足：金属离子的摩尔量与化合价数的乘积与氢氧根离子的摩尔量之比为0.75：1～1.25:1。
金属掺杂氧化锌薄膜中的掺杂金属的类型、掺杂金属带来的影响以及掺杂金属的掺杂含量如上文(电子传输层为第一电子传输层的情形)所述，为了节约篇幅，此处不再赘述。
在一些实施例中，金属掺杂氧化锌薄膜中的掺杂金属选自Mg 2+、Mn 2+中的至少一种。在一些实施例中，金属掺杂氧化锌薄膜中的掺杂金属选自Al 3+、Y 3+、La 3+、Li +、Gd 3+、Zr 4+、Ce 4+中的至少一种。掺杂金属离子的掺杂量参见上文，此处不再赘述。
应当理解，本申请上述三种实施方式中，当器件为正置量子点发光二极管时，在制备电子传输层之后，还包括在电子传输层上蒸镀阴极，得到量子点发光二极管。在一些实施例中，在蒸镀阴极之前，还包括在电子传输层上制备电子注入层。当器件为倒置量子点发光二极管时，在制备电子传输层之后，还包括在电子传输层上制备两点发光层，在量子点发光层上蒸镀阳极，得到量子点发光二极管。在一些实施例中，在蒸镀阳极之前，还包括在量子点发光层上制备空穴功能层。
本申请实施例中，空穴功能层(包括空穴注入层、空穴传输层和电子阻挡层中的至少一层)、量子点发光层的形成方法，优选采用溶液加工法，包括但不局限于旋涂法、刮涂法、印刷法、喷涂法、滚涂法、电沉积法等中的一种。
在第四种实施方式中，本申请实施例提供一种量子点发光二极管的制备方法，量子点发光二极管包括量子点发光二极管包括相对设置的阳极和阴极，设置在阳极和阴极之间的量子点发光层，设置在量子点发光层和阴极之间的电子传输层，其中，电子传输层包括含有氧化锌的第一电子传输层，且形成第一电子传输层的氧化锌表面含有碳原子数为8-18的胺基配体和/或羧基配体；
其中，如图9所示，第一电子传输层的制备方法为：
S41.采用锌盐溶液、碱液和碳原子数为8-18的胺基配体和/或羧基配体作为原料，通过溶液法制备氧化锌胶体溶液；其中，氧化锌溶液中的氧化锌表面结合有碳原子数为8-18的胺基配体和/或羧基配体；
S42.在待制备第一电子传输层的预制器件基板上形成氧化锌胶体溶液，去除溶剂，制得第一电子传输层。
本申请实施例提供的量子点发光二极管的制备方法，通过在合成氧化锌胶体溶液的过程中添加碳原子数为8-18的胺基配体和/或羧基配体，促使胺基配体和/或羧基配体和氧化锌胶体表面的羟基配体进行配体交换，进而将碳原子数为8-18的胺基配体和/或羧基配体配位在氧化锌胶体的表面。由于配位的碳原子数为8-18的胺基配体和/或羧基配体的链长较长，在空间位阻效应的作用下，增加了溶液中以及成膜后的氧化锌纳米颗粒之间的距离，进而降低了电子传输层的电子迁移率，抑制电子在电子传输层中的传输，降低电子在量子点发光二极管中的传输，从而减少量子点发光层中注入的电子，实现量子点发光二极管中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管。
本申请实施例中，量子点发光二极管的组成，特别是电子传输层的情形，碳原子数为8-18的胺基配体和/或羧基配体的选择及其含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜的厚度情况，如上文第一方面，为了节约篇幅，此处不再赘述。
上述步骤S41中，溶液法制备氧化锌的基本流程为：将锌盐溶液与碱液混合，反应生成氢氧化物中间体如氢氧化锌；氢氧化物中间体发生缩聚反应逐步生成氧化锌纳米颗粒。在此基础上，本申请实施例通过在合成氧化锌胶体溶液的过程中，添加链长为8-18个碳的胺基配体和/或羧基配体，使胺基配体和/或羧基配体与氧化锌胶体表面的羟基配体之间进行配体交换，进而将8-18个碳的胺基配体和/或羧基配体配位在氧化锌胶体的表面。由于配位的胺基/羧基配体的链长较长，在空间位阻效应的作用下，增加了氧化锌胶体溶液中以及成膜后氧化锌纳米颗粒之间的距离，进而降低了成膜后氧化锌电子传输层的电子迁移率，实际上发挥了和氧化锌薄膜表面羟基量大于或等于0.6相同的作用。
采用锌盐溶液、碱液和碳原子数为8-18的胺基配体和/或羧基配体作为原料，通过溶液法制备氧化锌胶体溶液的方法中，添加碳原子数为8-18的胺基配体和/或羧基配体的时间节点有多个，制备溶液法制备氧化锌胶体溶液的方式对应有几种。
在第一种实现方式中，在氧化锌胶体溶液合成初期添加碳原子数为8-18的胺基配体和/或羧基配体，即添加碳原子数为8-18的胺基配体和/或羧基配体和碱液同时添加到锌盐溶液。
此时，通过溶液法制备氧化锌胶体溶液的步骤，包括：
将锌盐溶液、碱液和碳原子数为8-18的胺基配体和/或羧基配体混合反应，制备表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒；
将氧化锌纳米颗粒溶解，得到氧化锌胶体溶液。
上述步骤中，锌盐溶液为锌盐溶解在溶剂形成的盐溶液。其中，锌盐选择能够与碱液反应生成锌的氢氧化物的盐，包括但不局限于醋酸锌、硝酸锌、硫酸锌、氯化锌中的一种。溶剂选择对锌盐具有溶解性的溶剂，包括但不局限于水、有机醇、有机醚、砜等极性较大的溶剂。在一些实施例中，溶剂选自水、有机醇、有机醚、砜中的至少一种。这类溶剂对锌盐具有较好的溶解性，作为反应介质在碱性环境中比较稳定，不容易引入副反应。示例性的，溶剂可选择水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、二甲基亚砜(DMSO)中的至少一种。
本申请实施例中，碱液为能够与锌盐反应生成锌的氢氧化物的碱形成的溶液。碱液通过溶剂溶解或稀释获得。其中，碱液中的碱，可以选择无机碱，也可以选择有机碱。在一种可能的实施方式中，碱液中的碱为无机碱，示例性的，无机碱选自氢氧化钾、氢氧化钠、氢氧化锂中的至少一种。在一种可能的实施方式中，碱液中的碱为有机碱，示例性的，弱碱选自TMAH、氨水、乙醇胺、乙二胺中的至少一种。在一些实施例中，用于溶解或稀释碱形成碱液的溶剂，可以与锌盐溶液中的溶剂相同，也可以与锌盐溶液中的溶剂不同。在一些实施例中，用于溶解或稀释碱形成碱液的溶剂溶剂选择与锌盐溶液相同的溶剂，更有利于获得稳定的反应体系。其中，相同的溶剂包括但不局限于水、有机醇、有机醚、砜等极性较大的溶剂。在一些实施例中，溶剂选自水、有机醇、有机醚、砜中的至少一种。示例性的，溶剂可选择水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、二甲基亚砜(DMSO)中的至少一种。
在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体包括但不局限于辛酸、辛胺、十二酸、十二胺、油酸、油胺。在一些实施例中，将碳原子数为8-18的胺基配体和/或羧基配体配置成配体溶液 后，与锌盐溶液和碱液混合反应。配体溶液中的溶剂，选择极性较大的溶剂，主要考虑对反应原料和产物的溶解性。示例性的，配体溶液中的溶剂选自甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体为配体溶液，且配体溶液的浓度为0.2-0.4mmol/L。当浓度过低时，碳原子数为8-18的胺基配体和/或羧基配体加入量过少，不易起到有效的配体交换作用；而当浓度过高时，碳原子数为8-18的胺基配体和/或羧基配体加入量过多，会对氧化锌胶体溶液的极性产生影响，进而影响下一步清洗的效果。
在一些实施例中，碱液的添加量满足：碱液提供的氢氧根离子与锌盐提供的锌离子的摩尔比为1.5:1～2.5:1，以确保氧化锌纳米颗粒的形成，并减少反应副产物的生成。当氢氧根离子与锌离子的摩尔比小于1.5：1时，锌盐显著过量，导致大量锌盐不易生成氧化锌纳米颗粒；而当氢氧根离子与锌离子的摩尔比大于2.5：1时，碱液显著过量，过量的氢氧根离子与氢氧化锌中间体形成稳定的络合物，不易缩聚生成氧化锌纳米颗粒。在一些实施例中，将锌盐溶液与碱液混合处理的步骤中，锌盐溶液与碱液的添加量满足：碱液提供的氢氧根离子的摩尔量与锌盐提供的锌离子的摩尔量之比为1.7:1～1.9:1。
在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：碳原子数为8-18的胺基配体和/或羧基配体与锌盐溶液中的锌盐的摩尔比为1:1～10:1。在这种情况下，加入的碳原子数为8-18的胺基配体和/或羧基配体结合在产生的氧化锌纳米颗粒中的表面，从而使氧化锌薄膜借助使碳原子数为8-18的胺基配体和/或羧基配体，降低电子传输效率，进而平衡量子点发光二极管中载流子注入平衡，从而有利于提高器件的外量子效率。但同时，碳原子数为8-18的胺基配体和/或羧基配体添加量太少时，连接在氧化锌表面的长链配体会较少，不易起到降低电子传输效率，提高EQE的目的；而当配体添加量太多时，氧化锌表面会有过多的长链配体连接，氧化锌纳米颗粒的亲疏水性会由亲水向疏水转变，导致在极性溶剂中的溶解性变差，影响最终器件中的成膜性及器件性能。
当配体链长较长(13-18)时，配体交换后样品的电子迁移率会有的下降，因此链长较长的配体添加量不多时也可以达到降低电子迁移率，提高EQE的目的，此外链长较长配体添加量过多时，会降低氧化锌纳米颗粒在极性溶剂中的溶解性，影响最终器件中氧化锌层的成膜性，降低最终器件的器件性能；而当配体链长较短(8-12)时，配体交换后电子迁移率下降的幅度较小，因此链长较多配体的添加量需要高一些才能实现提高EQE的目的。在一些实施例中，胺基配体和/或羧基配体的碳原子数为8-12，且胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与锌盐溶液中的锌盐的摩尔比为4:1～10:1。在一些实施例中，胺基配体和/或羧基配体的碳原子数为13-18，且胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与锌盐溶液中的锌盐的摩尔比为1:1～5:1。
在一些实施例中，在温度为0～70℃的条件下，将锌盐溶液、碱液和碳原子数为8-18的胺基配体和/或羧基配体，反应30分钟～4h，以制备表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒。在一些实施例中，锌盐溶液与碱液混合处理的方式为：在室温(5℃～40℃)下溶解锌盐获得锌盐溶液，在室温下溶解或稀释碱获得碱液，在室温下溶解碳原子数为8-18的胺基配体和/或羧基配体获得配体溶液；将锌盐溶液的温度调整至0～70℃，加入碱液和配体溶液。在这种情况下，加入的碱与锌盐溶液中的锌盐反应，生成氧化锌纳米颗粒，加入的配体与氧化锌纳米颗粒表面的羟基配体交换，制得表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒，并能获得良好的颗粒分散性。当反应温度低于0℃时，会显著减缓氧化锌纳米颗粒的生成，甚至不易生成氧化锌纳米颗粒，而只能得到氢氧化物中间体；而当反应温度高于70℃时，所得氧化锌纳米颗粒的团聚严重，分散性较差，影响氧化锌胶体溶液的后期成膜。在一些实施例中，锌盐溶液与碱液的反应温度为室温～50℃，在这种情况下，不仅有利于氧化锌纳米颗粒的形成，而且得到的氧化锌离子具有较好的颗粒分散性，有利于氧化锌胶体溶液的成膜。
在一些实施例中，将锌盐溶液与碱液混合处理的步骤中，按照氢氧根离子与锌离子的摩尔比为1.5:1～2.5:1的比例，将锌盐溶液与碱液混合处理，以确保氧化锌纳米颗粒的形成，并减少反应副产物的生成。当氢氧根离子与锌离子的摩尔比小于1.5：1时，锌盐显著过量，导致大量锌盐不易生成氧化锌纳米颗粒；而当氢氧根离子与锌离子的摩尔比大于2.5：1时，碱液显著过量，过量的氢氧根离子与氢氧化锌中间体形成稳定的络合物，不易缩聚生成氧化锌纳米颗粒。在一些实施例中，将锌盐溶液与碱液混合 处理的步骤中，锌盐溶液与碱液的添加量满足：碱液提供的氢氧根离子的摩尔量与锌盐提供的锌离子的摩尔量之比为1.7:1～1.9:1。
在一些实施例中，将锌盐溶液与碱液混合后，在反应温度下反应30分钟～4h以确保氧化锌纳米颗粒的形成，并控制纳米粒子的粒径。当反应时间少于30分钟时，反应时间过短，氧化锌纳米颗粒形成不充分，并且所得纳米粒子的结晶性较差；而当反应时间超过4h时，过长的颗粒长大时间使生成的纳米粒子过大并且粒径不均匀，影响氧化锌胶体溶液的后期成膜性。在一些实施例中，加入所述碳原子数为8-18的胺基配体和/或羧基配体后，反应10分钟-2小时。在一些实施例中，将锌盐溶液与碱液混合后，在反应温度下反应1～2h。
在一些实施例中，在温度为0～70℃的条件下，将锌盐溶液、碱液和碳原子数为8-18的胺基配体和/或羧基配体混合，搅拌反应，以促进反应的均匀性和得到的氧化锌纳米颗粒的颗粒均匀性。
在一些实施例中，反应结束后，向反应结束后的混合溶液中加入沉淀剂，收集沉淀物。沉淀剂选择与终产物氧化锌纳米颗粒极性相反的溶剂，从而通过降低氧化锌纳米颗粒的溶解性，将其沉淀下来。在一些实施例中，沉淀剂选择极性较弱的溶剂，这类沉淀剂与氧化锌纳米颗粒的极性相反，有利于氧化锌纳米颗粒的沉淀。示例性的，沉淀剂包括但不局限于乙酸乙酯、丙酮、正己烷、正庚烷，以及其余低极性的长链烷烃等。
在一些实施例中，向反应结束后的混合溶液中加入2～6倍体积的沉淀剂(即：沉淀剂与混合溶液的体积比为2:1～6:1)，混合溶液中产生白色沉淀。在这种情况下，确保在充分沉淀氧化锌纳米颗粒的前提下，不会因为沉淀剂过多导致氧化锌粒子溶解性受到破坏的情况。在一些实施例中，沉淀剂与混合溶液的体积比为3:1～5:1。
本申请实施例中，将经沉淀处理的混合体系进行离心处理，收集沉淀物。在一些实施例中，采用反应溶剂对收集到的沉淀物进行清洗处理，以去除没有参与反应的反应物。采用反应溶剂对得到的氧化锌纳米颗粒进行清洗，能够将制备氧化锌纳米颗粒的多余锌盐、碱等原料去除，以提高氧化锌纳米颗粒的纯度。应当注意的是，反应溶剂如上文。在一些实施例中，反应溶剂选自水、有机醇、有机醚、砜中的至少一种。这类反应溶剂的极性较大，能够有效去除氧化锌纳米颗粒中残余的锌盐、碱等原料杂质以及中间体杂质。示例性的，反应溶剂选自水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。
将经清洗处理后的沉淀物进行溶解，得到氧化锌胶体溶液。
在第二种实现方式中，在氧化锌胶体溶液合成中期添加碳原子数为8-18的胺基配体和/或羧基配体，即向已经添加了碱液的氧化锌前驱物溶液中添加碳原子数为8-18的胺基配体和/或羧基配体。
此时，通过溶液法制备氧化锌胶体溶液的步骤，包括：
将锌盐溶液与碱液混合反应，在反应过程中加入碳原子数为8-18的胺基配体和/或羧基配体，制备表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒；其中，加入碳原子数为8-18的胺基配体和/或羧基配体后的反应时间大于或等于10分钟；
将氧化锌纳米颗粒溶解，得到氧化锌胶体溶液。
上述步骤中，锌盐溶液为锌盐溶解在溶剂形成的盐溶液，碱液为能够与锌盐反应生成锌的氢氧化物的碱形成的溶液。其中，锌盐溶液中锌盐和溶剂的选择，碱液中的碱及其形成方式、溶剂选择，反应体系中锌盐和碱液的添加比例，如上述第一种实现方式所述。
在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体包括但不局限于辛酸、辛胺、十二酸、十二胺、油酸、油胺。在一些实施例中，将碳原子数为8-18的胺基配体和/或羧基配体配置成配体溶液后，与锌盐溶液和碱液混合反应。配体溶液中的溶剂，选择极性较大的溶剂，主要考虑对反应原料和产物的溶解性。示例性的，配体溶液中的溶剂选自甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体为配体溶液，且配体溶液的浓度为0.2-0.4mmol/L。当浓度过低时，碳原子数为8-18的胺基配体和/或羧基配体加入量过少，不易起到有效的配体交换作用；而当浓度过高时，碳原子数为8-18的胺基配体和/或羧基配体加入量过多，会对氧化锌胶体溶液的极性产生影响，进而影响下一步清洗的效果。
本申请实施例中，将锌盐溶液与碱液混合反应的反应温度和时间，如上述第一种实现施方式所述。
本申请实施例中，在反应过程中加入碳原子数为8-18的胺基配体和/或羧基配体，制备表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒。
在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：碳原子数为8-18的胺基配体和/或羧基配体与锌盐溶液中的锌盐的摩尔比为1:1～10:1。在这种情况下，加入的碳原子数为8-18的胺基配体和/或羧基配体结合在产生的氧化锌纳米颗粒中的表面，从而使氧化锌薄膜借助使碳原子数为8-18的胺基配体和/或羧基配体，降低电子传输效率，进而平衡量子点发光二极管中载流子注入平衡，从而有利于提高器件的外量子效率。但同时，碳原子数为8-18的胺基配体和/或羧基配体添加量太少时，连接在氧化锌表面的长链配体会较少，不易起到降低电子传输效率，提高EQE的目的；而当配体添加量太多时，氧化锌表面会有过多的长链配体连接，氧化锌纳米颗粒的亲疏水性会由亲水向疏水转变，导致在极性溶剂中的溶解性变差，影响最终器件中的成膜性及器件性能。
当配体链长较长(13-18)时，配体交换后样品的电子迁移率会有的下降，因此链长较长的配体添加量不多时也可以达到降低电子迁移率，提高EQE的目的，此外链长较长配体添加量过多时，会降低氧化锌纳米颗粒在极性溶剂中的溶解性，影响最终器件中氧化锌层的成膜性，降低最终器件的器件性能；而当配体链长较短(8-12)时，配体交换后电子迁移率下降的幅度较小，因此链长较多配体的添加量需要高一些才能实现提高EQE的目的。在一些实施例中，胺基配体和/或羧基配体的碳原子数为8-12，且胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与锌盐溶液中的锌盐的摩尔比为4:1～10:1。在一些实施例中，胺基配体和/或羧基配体的碳原子数为13-18，且胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与锌盐溶液中的锌盐的摩尔比为1:1～5:1。
应当注意的是，加入碳原子数为8-18的胺基配体和/或羧基配体后继续反应的反应时间大于或等于10分钟，使配体与生成的氧化锌纳米颗粒表面的羟基充分交换。在一些实施例中，在反应过程中加入碳原子数为8-18的胺基配体和/或羧基配体后，搅拌处理，搅拌时间为10分钟-2h，以使交换反应充分进行。在一些实施例中，搅拌时间为30分钟-1h。
在一些实施例中，反应结束后，向反应结束后的混合溶液中加入沉淀剂，收集沉淀物。沉淀剂的选择、添加量如上述第一种实现方式所述。
本申请实施例中，将经沉淀处理的混合体系进行离心处理，收集沉淀物。在一些实施例中，采用反应溶剂对收集到的沉淀物进行清洗处理，以去除没有参与反应的反应物。采用反应溶剂对得到的氧化锌纳米颗粒进行清洗，能够将制备氧化锌纳米颗粒的多余锌盐、碱等原料去除，以提高氧化锌纳米颗粒的纯度。应当注意的是，反应溶剂如上文。在一些实施例中，反应溶剂选自水、有机醇、有机醚、砜中的至少一种。这类反应溶剂的极性较大，能够有效去除氧化锌纳米颗粒中残余的锌盐、碱等原料杂质以及中间体杂质。示例性的，反应溶剂选自水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。
将经清洗处理后的沉淀物进行溶解，得到氧化锌胶体溶液。
在第三种实现方式中，在制得氧化锌胶体溶液后添加碳原子数为8-18的胺基配体和/或羧基配体。
此时，通过溶液法制备氧化锌胶体溶液的步骤，包括：
将锌盐溶液与碱液混合反应3制得氧化锌纳米颗粒后，加入碳原子数为8-18的胺基配体和/或羧基配体，继续反应，制备制备表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒；
将氧化锌纳米颗粒溶解，得到氧化锌胶体溶液。
上述步骤中，锌盐溶液为锌盐溶解在溶剂形成的盐溶液，碱液为能够与锌盐反应生成锌的氢氧化物的碱形成的溶液。其中，锌盐溶液中锌盐和溶剂的选择，碱液中的碱及其形成方式、溶剂选择，反应体系中锌盐和碱液的添加比例，如上述第一种实现方式所述。
在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体、配体溶液中的溶剂选择以及配体溶液的浓度，如上述第一种实现方式所述。
本申请实施例中，将锌盐溶液与碱液混合反应的反应温度和时间，如上述第一种实现施方式所述。
本申请实施例中，在反应制得氧化锌纳米颗粒后加入碳原子数为8-18的胺基配体和/或羧基配体， 制备表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒。
在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：碳原子数为8-18的胺基配体和/或羧基配体与锌盐溶液中的锌盐的摩尔比为1:1～10:1。在这种情况下，加入的碳原子数为8-18的胺基配体和/或羧基配体结合在产生的氧化锌纳米颗粒中的表面，从而使氧化锌薄膜借助使碳原子数为8-18的胺基配体和/或羧基配体，降低电子传输效率，进而平衡量子点发光二极管中载流子注入平衡，从而有利于提高器件的外量子效率。但同时，碳原子数为8-18的胺基配体和/或羧基配体添加量太少时，连接在氧化锌表面的长链配体会较少，不易起到降低电子传输效率，提高EQE的目的；而当配体添加量太多时，氧化锌表面会有过多的长链配体连接，氧化锌纳米颗粒的亲疏水性会由亲水向疏水转变，导致在极性溶剂中的溶解性变差，影响最终器件中的成膜性及器件性能。
当配体链长较长(13-18)时，配体交换后样品的电子迁移率会有的下降，因此链长较长的配体添加量不多时也可以达到降低电子迁移率，提高EQE的目的，此外链长较长配体添加量过多时，会降低氧化锌纳米颗粒在极性溶剂中的溶解性，影响最终器件中氧化锌层的成膜性，降低最终器件的器件性能；而当配体链长较短(8-12)时，配体交换后电子迁移率下降的幅度较小，因此链长较多配体的添加量需要高一些才能实现提高EQE的目的。在一些实施例中，胺基配体和/或羧基配体的碳原子数为8-12，且胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与锌盐溶液中的锌盐的摩尔比为4:1～10:1。在一些实施例中，胺基配体和/或羧基配体的碳原子数为13-18，且胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与锌盐溶液中的锌盐的摩尔比为1:1～5:1。
应当注意的是，加入碳原子数为8-18的胺基配体和/或羧基配体后继续反应的反应时间大于或等于10分钟，使配体与生成的氧化锌纳米颗粒表面的羟基充分交换。在一些实施例中，在反应过程中加入碳原子数为8-18的胺基配体和/或羧基配体后，搅拌处理，搅拌时间为10分钟-2h，以使交换反应充分进行。在一些实施例中，搅拌时间为30分钟-1h。
在一些实施例中，反应结束后，向反应结束后的混合溶液中加入沉淀剂，收集沉淀物。沉淀剂的选择沉淀剂的选择、添加量如上述第一种实现方式所述。
本申请实施例中，将经沉淀处理的混合体系进行离心处理，收集沉淀物。在一些实施例中，采用反应溶剂对收集到的沉淀物进行清洗处理，以去除没有参与反应的反应物。采用反应溶剂对得到的氧化锌纳米颗粒进行清洗，能够将制备氧化锌纳米颗粒的多余锌盐、碱等原料去除，以提高氧化锌纳米颗粒的纯度。应当注意的是，反应溶剂如上文。在一些实施例中，反应溶剂选自水、有机醇、有机醚、砜中的至少一种。这类反应溶剂的极性较大，能够有效去除氧化锌纳米颗粒中残余的锌盐、碱等原料杂质以及中间体杂质。示例性的，反应溶剂选自水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。
将经清洗处理后的沉淀物进行溶解，得到氧化锌胶体溶液。
在第四种实现方式中，在制得氧化锌纳米颗粒，且对氧化锌纳米颗粒进行清洗后添加碳原子数为8-18的胺基配体和/或羧基配体。
此时，通过溶液法制备氧化锌胶体溶液的步骤，包括：
将锌盐溶液与碱液混合反应后，收集产物清洗处理，得到氧化锌纳米颗粒；
将氧化锌纳米颗粒溶解后，加入碳原子数为8-18的胺基配体和/或羧基配体反应，在氧化锌表面结合碳原子数为8-18的胺基配体和/或羧基配体，得到氧化锌胶体溶液。
上述步骤中，锌盐溶液为锌盐溶解在溶剂形成的盐溶液，碱液为能够与锌盐反应生成锌的氢氧化物的碱形成的溶液。其中，锌盐溶液中锌盐和溶剂的选择，碱液中的碱及其形成方式、溶剂选择，反应体系中锌盐和碱液的添加比例，如上述第一种实现方式所述。
实施例中，将锌盐溶液反应的反应温度和时间，如上述第一种实现施方式所述。
在一些实施例中，反应结束后，向反应结束后的混合溶液中加入沉淀剂，收集沉淀物。沉淀剂的选择沉淀剂的选择、添加量如上述第一种实现方式所述。
本申请实施例中，将经沉淀处理的混合体系进行离心处理，收集产物。在一些实施例中，采用反应溶剂对收集到的产物进行清洗处理，以去除没有参与反应的反应物。采用反应溶剂对得到的氧化锌纳米 颗粒进行清洗，能够将制备氧化锌纳米颗粒的多余锌盐、碱等原料去除，以提高氧化锌纳米颗粒的纯度。应当注意的是，反应溶剂如上文。在一些实施例中，反应溶剂选自水、有机醇、有机醚、砜中的至少一种。这类反应溶剂的极性较大，能够有效去除氧化锌纳米颗粒中残余的锌盐、碱等原料杂质以及中间体杂质。示例性的，反应溶剂选自水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。
本申请实施例中，将氧化锌纳米颗粒溶解后，加入碳原子数为8-18的胺基配体和/或羧基配体反应，在氧化锌表面结合碳原子数为8-18的胺基配体和/或羧基配体，得到氧化锌胶体溶液。
在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体包括但不局限于辛酸、辛胺、十二酸、十二胺、油酸、油胺。在一些实施例中，将碳原子数为8-18的胺基配体和/或羧基配体配置成配体溶液后，与锌盐溶液和碱液混合反应。配体溶液中的溶剂，选择极性较大的溶剂，主要考虑对反应原料和产物的溶解性。示例性的，配体溶液中的溶剂选自甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体为配体溶液，且配体溶液的浓度为0.05-0.1mmol/L。当浓度过低时，碳原子数为8-18的胺基配体和/或羧基配体加入量过少，不易起到有效的配体交换作用；本实施例在清洗之后最终得到的氧化锌胶体溶液中添加胺基/羧基配体溶液，后续不再有清洗提纯过程，因此，当浓度过高时，碳原子数为8-18的胺基配体和/或羧基配体加入量过多，剩余的配体将直接残留在最终的氧化锌电子传输层薄膜中，多余的配体对氧化锌电子传输层的成膜品质及性质产生影响。
在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：碳原子数为8-18的胺基配体和/或羧基配体与锌盐溶液中的锌盐的摩尔比为1:4～4:1。在这种情况下，加入的碳原子数为8-18的胺基配体和/或羧基配体结合在产生的氧化锌纳米颗粒中的表面，降低氧化锌电子传输层的电子迁移率，从而提高器件的初始EQE。但同时，碳原子数为8-18的胺基配体和/或羧基配体添加量太少时，连接在氧化锌表面的长链配体会较少，不易起到降低电子传输效率，提高EQE的目的；而当配体添加量太多时，氧化锌表面会有过多的长链配体连接，氧化锌纳米颗粒的亲疏水性会由亲水向疏水转变，导致在极性溶剂中的溶解性变差，影响最终器件中的成膜性及器件性能。
当配体链长较长(13-18)时，配体交换后样品的电子迁移率会有的下降，因此链长较长的配体添加量不多时也可以达到降低电子迁移率，提高EQE的目的，此外链长较长配体添加量过多时，会降低氧化锌纳米颗粒在极性溶剂中的溶解性，影响最终器件中氧化锌层的成膜性，降低最终器件的器件性能；而当配体链长较短(8-12)时，配体交换后电子迁移率下降的幅度较小，因此链长较多配体的添加量需要高一些才能实现提高EQE的目的。在一些实施例中，胺基配体和/或羧基配体的碳原子数为8-12，且胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与锌盐溶液中的锌盐的摩尔比为1:1～10:1。在一些实施例中，胺基配体和/或羧基配体的碳原子数为13-18，且胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与锌盐溶液中的锌盐的摩尔比为1:4～5:1。
应当注意的是，加入碳原子数为8-18的胺基配体和/或羧基配体后继续反应的反应时间大于或等于10分钟，使配体与生成的氧化锌纳米颗粒表面的羟基充分交换。在一些实施例中，在反应过程中加入碳原子数为8-18的胺基配体和/或羧基配体后，搅拌处理，搅拌时间为10分钟-2h，以使交换反应充分进行。在一些实施例中，搅拌时间为30分钟-1h。
上述步骤S42中，可以根据制备的量子点发光二极管器件的类型，在预制器件基板上形成上述氧化锌胶体溶液，去除溶剂，制得氧化锌表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜。
在一些实施例中，在预制器件基板上形成上述氧化锌胶体溶液，可以采用包括但不局限于旋涂法、刮涂法、印刷法、喷涂法、滚涂法、电沉积法等中的一种。在预制器件基板上形成上述氧化锌胶体溶液后，通过退火处理去除溶剂，得到氧化锌表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜。
在一种可能的实施方式中，量子点发光二极管为正置量子点发光二极管，预制器件基板包括阳极基板，结合在阳极基板上的量子点发光层。在一些实施例中，预制器件基板还包括设置在阳极基板和量子 点发光层之间的空穴功能层。其中，空穴功能层包括空穴传输层、空穴注入层和电子阻挡层中的至少一种。
在一种可能的实施方式中，量子点发光二极管为倒置量子点发光二极管，预制器件基板为阴极基板。在一些实施例中，预制器件基板还包括结合在阴极基板的阴极表面的电子注入层。
在一些实施例中，第一电子传输层可以单独作为电子传输层。
在一些实施例中，电子传输层包括两层氧化锌薄膜或包括n个由两层氧化锌薄膜组成的薄膜叠层单元，两层氧化锌薄膜分别命名为第一电子传输层和第二电子传输层，n大于或等于2。在一些实施例中，n为大于或等于2且小于或等于9的整数。其中，至少第一电子传输层为上述方法制备的表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜，第二电子传输层的情形，可以参考上文量子点发光二极管器件第二电子传输层中的情形。
在一些实施例中，第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜，或第二电子传输层为金属掺杂氧化锌薄膜。其中，第一电子传输层可以设置在邻近量子点发光层的一侧，也可以设置在邻近阴极的一侧。优选的，第二电子传输层设置在邻近量子点发光层的一侧或金属掺杂氧化锌薄膜设置在邻近量子点发光层的一侧，可以得到更加平整的氧化锌薄膜。
在一些实施例中，电子传输层包括三层氧化锌薄膜，三层氧化锌薄膜分别命名为第一电子传输层、第二电子传输层和第三电子传输层。其中，至少第一电子传输层为上述方法制备的表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜，第二电子传输层和第三电子传输层的情形，可以参考上文量子点发光二极管器件中电子传输层包含第三电子传输层的情形。
上述实施例中，表面羟基量大于或等于0.6的氧化锌薄膜，可以通过表面羟基量大于或等于0.6的氧化锌胶体溶液形成。
上述实施例中，表面羟基量小于或等于0.4的氧化锌薄膜，可以通过表面羟基量小于或等于0.4的氧化锌胶体溶液形成。
上述实施例中，金属掺杂氧化锌薄膜，可以按照下述方法制备获得：
在温度为0～70℃的条件下，将含有掺杂金属离子的锌盐溶液与碱液混合，反应30分钟～4h；向反应结束后的混合溶液中加入沉淀剂，收集沉淀物；采用反应溶剂对沉淀物进行清洗处理后，将得到的白色沉淀物溶解，得到掺杂金属氧化锌胶体溶液；将掺杂掺杂金属氧化锌胶体溶液形成在待制备金属掺杂氧化锌薄膜的基板上，制得金属掺杂氧化锌薄膜。该实施例中，锌盐溶液的锌盐和溶剂类型以及锌盐溶液的含量、掺杂离子的类型和掺杂含量、碱液的类型和添加量、反应温度和反应时间、沉淀剂的选择和添加量，均参照本申请实施例上述步骤S11进行。该方法中，含有掺杂金属离子的锌盐溶液可以通过将锌盐和选定的金属盐按一定比例在室温下溶解在溶剂中获得。将含有掺杂金属离子的锌盐溶液与碱液混合的步骤中，碱的添加量满足：金属离子的摩尔量与化合价数的乘积与氢氧根离子的摩尔量之比为0.75：1～1.25:1。
在第五种实施方式中，本申请实施例提供一种量子点发光二极管的制备方法，量子点发光二极管包括相对设置的阳极和阴极，设置在阳极和阴极之间的量子点发光层，设置在量子点发光层和阴极之间的电子传输层，其中，电子传输层包括第一电子传输层，且至少第一电子传输层的一侧表面含有碳原子数为8-18的胺基配体和/或羧基配体；
其中，如图10所示，第一电子传输层的制备方法，包括：
S51.在待制备第一电子传输层的预制器件基板上制备氧化锌预制薄膜；
S52.在氧化锌预制薄膜的表面沉积碳原子数为8-18的胺基配体和/或羧基配体溶液后进行干燥处理，得到氧化锌薄膜。
本申请实施例提供的量子点发光二极管的制备方法，在氧化锌预制薄膜的表面沉积碳原子数为8-18的胺基配体和/或羧基配体溶液，促使胺基配体和/或羧基配体和氧化锌胶体表面的羟基配体进行配体交换，进而将碳原子数为8-18的胺基配体和/或羧基配体配位在氧化锌胶体的表面。由于配位的碳原子数为8-18的胺基配体和/或羧基配体的链长较长，在空间位阻效应的作用下，增加了溶液中以及成膜后的氧化锌纳米颗粒之间的距离，进而降低了电子传输层的电子迁移率，抑制电子在电子传输层中的传输， 降低电子在量子点发光二极管中的传输，从而减少量子点发光层中注入的电子，实现量子点发光二极管中载流子的注入平衡，最终得到具有较高外量子效率的量子点发光二极管。
本申请实施例中，量子点发光二极管的组成，特别是电子传输层的情形，如上文第一方面，为了节约篇幅，此处不再赘述。
上述步骤S51中，氧化锌预制薄膜可以通过多种方式制备获得，示例性的，通过溶液法或溶胶凝胶法制备氧化锌预制薄膜。
在一些实施例中，氧化锌预制薄膜通过溶液法制备获得，包括：将锌盐溶液与碱液混合反应，制备氧化锌纳米颗粒；将氧化锌纳米颗粒溶解，得到氧化锌胶体溶液；在待制备第一电子传输层的预制器件基板上形成氧化锌胶体溶液，去除溶剂，制得氧化锌预制薄膜。
通过溶液法制备氧化锌胶体溶液，溶液法可以是醇解法、水解法等中的一种。溶液法制备氧化锌的基本流程为：将锌盐溶液与碱液混合，反应生成氢氧化物中间体如氢氧化锌；氢氧化物中间体发生缩聚反应逐步生成氧化锌纳米颗粒。
本申请实施例中，锌盐溶液、锌盐溶液中的锌盐及溶剂的选择依据、类型，以及锌盐溶液的形成方式如上述第一种实施方式。
本申请实施例中，碱液、碱液中的碱及溶剂的选择依据、类型，以及碱液的形成方式如上述第一种实施方式。
在一些实施例中，在温度为0～70℃的条件下，将锌盐溶液与碱液混合处理，反应30min～4h，以制备氧化锌纳米颗粒。在一些实施例中，锌盐溶液与碱液混合处理的方式为：在室温(5℃～40℃)下溶解锌盐获得锌盐溶液，在室温下溶解或稀释碱获得碱液；将锌盐溶液的温度调整至0～70℃，加入碱液。在这种情况下，加入的碱与锌盐溶液中的锌盐反应，生成氧化锌纳米颗粒，并能获得良好的颗粒分散性。当反应温度低于0℃时，会显著减缓氧化锌纳米颗粒的生成，且反应需要借助特殊设备才能实现，增加了反应难度，甚至在一些条件下不易生成氧化锌纳米颗粒，而只能得到氢氧化物中间体；而当反应温度高于70℃时，反应活性过高，生成的氧化锌纳米颗粒团聚严重，不易得到分散性良好的胶体溶液，影响氧化锌胶体溶液的后期成膜。在一些实施例中，锌盐溶液与碱液的反应温度为室温～50℃，在这种情况下，不仅有利于氧化锌纳米颗粒的形成，而且得到的氧化锌离子具有较好的颗粒分散性，有利于氧化锌胶体溶液的成膜。在一些实施例中，在温度为0～30℃的条件下，将锌盐溶液与碱液混合处理，可以轻松生成合格的氧化锌胶体溶液；在一些实施例中，在温度为30℃～70℃的条件下，也可以生成氧化锌胶体溶液，得到的氧化锌胶体溶液品质不如0～30℃的条件下生成的氧化锌胶体溶液，同时反应时间也要减少。
在一些实施例中，将锌盐溶液与碱液混合处理的步骤中，按照氢氧根离子与锌离子的摩尔比为1.5:1～2.5:1的比例，将锌盐溶液与碱液混合处理，以确保氧化锌纳米颗粒的形成，并减少反应副产物的生成。当氢氧根离子与锌离子的摩尔比小于1.5：1时，锌盐显著过量，导致大量锌盐不易生成氧化锌纳米颗粒；而当氢氧根离子与锌离子的摩尔比大于2.5：1时，碱液显著过量，过量的氢氧根离子与氢氧化锌中间体形成稳定的络合物，不易缩聚生成氧化锌纳米颗粒。在一些实施例中，将锌盐溶液与碱液混合处理的步骤中，锌盐溶液与碱液的添加量满足：碱液提供的氢氧根离子的摩尔量与锌盐提供的锌离子的摩尔量之比为1.7:1～1.9:1。
本申请实施例中，将锌盐溶液与碱液混合后，在0～70℃的反应温度下反应30min～4h以确保氧化锌纳米颗粒的形成，并控制纳米粒子的粒径。当反应时间少于30min时，过低的反应时间反应得到的是氧化锌的团簇种子，此时样品的结晶状态不完整，晶体结构较差，如果将其用作电子传输层材料的话，会使得电子传输层的导电性很差；而当反应时间超过4h时，过长的颗粒长大时间使生成的纳米粒子过大并且粒径不均匀，氧化锌胶体溶液成膜后表面粗糙度会较高，影响电子的传输性能。在一些实施例中，将锌盐溶液与碱液混合后，在反应温度下反应1～2h。
在一些实施例中，在温度为0～70℃的条件下，将锌盐溶液与碱液混合，反应30min～4h，在搅拌的条件下进行，以促进反应的均匀性和得到的氧化锌纳米颗粒的颗粒均匀性，制得尺寸均匀的氧化锌纳米颗粒。
本申请实施例中，将制得的氧化锌纳米颗粒溶解，即可得到氧化锌胶体溶液。
在一些实施例中，获得氧化锌纳米颗粒的方法还包括：在反应结束后，向反应结束后的混合溶液中加入沉淀剂，收集沉淀物。沉淀剂选择与终产物氧化锌纳米颗粒极性相反的溶剂，从而通过降低氧化锌纳米颗粒的溶解性，将其沉淀下来。在一些实施例中，沉淀剂选择极性较弱的溶剂，这类沉淀剂与氧化锌纳米颗粒的极性相反，有利于氧化锌纳米颗粒的沉淀。示例性的，沉淀剂包括但不局限于乙酸乙酯、丙酮、正己烷、正庚烷，以及其余低极性的长链烷烃等。
在一些实施例中，向反应结束后的混合溶液中加入2～6倍体积的沉淀剂(即：沉淀剂与混合溶液的体积比为2:1～6:1)，混合溶液中产生白色沉淀。在这种情况下，确保在充分沉淀氧化锌纳米颗粒的前提下，不会因为沉淀剂过多导致氧化锌粒子溶解性受到破坏的情况。在一些实施例中，沉淀剂与混合溶液的体积比为3:1～5:1。
本申请实施例中，将经沉淀处理的混合体系进行离心处理，收集沉淀物。本申请实施例采用反应溶剂对收集到的沉淀物进行清洗处理，以去除没有参与反应的反应物。采用反应溶剂对得到的氧化锌纳米颗粒进行清洗，能够将制备氧化锌纳米颗粒的多余锌盐、碱等原料去除，以提高氧化锌纳米颗粒的纯度。应当注意的是，反应溶剂如上文。在一些实施例中，反应溶剂选自水、有机醇、有机醚、砜中的至少一种。示例性的，反应溶剂选自水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。
清洗处理后得到白色沉淀物，将得到的白色沉淀物溶解，得到氧化锌胶体溶液。
在一种可能的实施方式中，第一电子传输层为金属掺杂氧化锌薄膜，对应的，第一电子传输层中的氧化锌为金属掺杂氧化锌，此时，锌盐溶液中还含有掺杂金属离子。该实施例中，掺杂金属离子的选择以及掺杂含量，如上文金属掺杂氧化锌薄膜中的掺杂金属的选择。
本申请实施例中，可以根据制备的量子点发光二极管器件的类型，在待制备第一电子传输层的预制器件基板上形成上述氧化锌胶体溶液，去除溶剂，制得氧化锌预制薄膜。
在一些实施例中，在预制器件基板上形成上述氧化锌胶体溶液，可以采用包括但不局限于旋涂法、刮涂法、印刷法、喷涂法、滚涂法、电沉积法等中的一种。在预制器件基板上形成上述氧化锌胶体溶液后，通过退火处理去除溶剂，得到氧化锌预制薄膜。
在一些实施例中，通过溶胶凝胶法(高温煅烧法)制备氧化锌预制薄膜，具体的，将氧化锌前驱物直接旋涂在待制备氧化锌预制薄膜的基板上，然后高温热处理，使其变成氧化锌。
上述步骤S52中，通过在氧化锌预制薄膜上沉积碳原子数为8-18的胺基配体和/或羧基配体溶液，促使胺基配体和/或羧基配体和氧化锌胶体表面的羟基配体进行配体交换，进而将碳原子数为8-18的胺基配体和/或羧基配体配位在氧化锌胶体的表面。
本申请实施例中，碳原子数为8-18的胺基配体和/或羧基配体配位溶液是指将碳原子数为8-18的胺基配体和/或羧基配体配位溶解在溶剂中得到的配体溶液。在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体包括但不局限于辛酸、辛胺、十二酸、十二胺、油酸、油胺。在一些实施例中，选择极性较大的溶剂，主要考虑对反应原料和产物的溶解性。在一些实施例中，用于溶解碳原子数为8-18的胺基配体和/或羧基配体的溶剂，包括但不局限于水、醇类等极性较大的溶剂中的一种，示例性的，用于溶解碳原子数为8-18的胺基配体和/或羧基配体的溶剂选自水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。
本申请实施例中，需要对碳原子数为8-18的胺基配体和/或羧基配体溶液的浓度和添加量进行控制。这是因为：当浓度过低时，碳原子数为8-18的胺基配体和/或羧基配体加入量过少，不易起到有效的配体交换作用。而当配体浓度过高时，碳原子数为8-18的胺基配体和/或羧基配体加入量过多，溶液中剩余的大量配体将直接残留在最终的第一电子传输层中，对电子传输层的成膜品质及性质产生影响。在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体为配体溶液的浓度为0.05-0.1mmol/L。
在一些实施例中，碳原子数为8-18的胺基配体和/或羧基配体为配体溶液的浓度为0.05-0.1mmol/L，且在氧化锌预制薄膜的表面沉积碳原子数为8-18的胺基配体和/或羧基配体溶液后的步骤中，碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：每5mg氧化锌预制薄膜，沉积碳原子数为8-18的胺基配体和/或羧基配体溶液50μL-1000μL。
当配体链长较长(13-18)时，配体交换后样品的电子迁移率会有的下降，因此链长较长的配体添加量不多时也可以达到降低电子迁移率，提高EQE的目的，此外链长较长配体添加量过多时，会改变氧化锌纳米颗粒的极性，进而影响氧化锌薄膜的浸润性和成膜性，最终降低器件的器件性能；而当配体链长较短(8-12)时，配体交换后电子迁移率下降的幅度较小，因此链长较多配体的添加量需要高一些才能实现提高EQE的目的。在一些实施例中，当碳原子数为8-18的胺基配体和/或羧基配体的碳原子为8-12时，碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：每5mg氧化锌预制薄膜，沉积碳原子数为8-12的胺基配体和/或羧基配体溶液100μL-500μL；当碳原子数为8-18的胺基配体和/或羧基配体的碳原子为13-18时，碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：每5mg氧化锌预制薄膜，沉积碳原子数为13-18的胺基配体和/或羧基配体溶液50μL-300μL。
本申请实施例中，在氧化锌预制薄膜的表面沉积碳原子数为8-18的胺基配体和/或羧基配体溶液的方法可以采用溶液加工法，包括但不限于旋涂法、刮涂法、印刷法、喷涂法、滚涂法、电沉积法等中的一种。
在氧化锌预制薄膜的表面沉积碳原子数为8-18的胺基配体和/或羧基配体溶液后，进行干燥处理，通过干燥处理使碳原子数为8-18的胺基配体和/或羧基配体溶液中的配体与氧化锌表面的羟基充分交换。在一些实施例中，干燥处理的温度为10℃～100℃，干燥时间为10分钟～2小时。在这种情况下，碳原子数为8-18的胺基配体和/或羧基配体中的电配体与氧化锌表面的羟基充分反应，从而在空间位阻效应的作用下，增加成膜后氧化锌纳米颗粒之间的距离，进而降低了成膜后氧化锌电子传输层的电子迁移率。若干燥温度过高或干燥处理的时间过长，会导致碳原子数为8-18的胺基配体和/或羧基配体迅速烘干，氧化锌预制薄膜迅速变成固体膜，进而使得碳原子数为8-18的胺基配体和/或羧基配体中的配体子与氧化锌表面的羟基不易进行充分的反应；而当干燥温度过低或干燥处理的时间过短时，会导致氧化锌预制薄膜较难充分干燥，影响下一层的制备，特别是影响电极的蒸镀质量。在一些实施例中，干燥处理的温度为10℃～50℃，干燥时间为30分钟～2小时。
在一种可能的实施方式中，量子点发光二极管为正置量子点发光二极管，预制器件基板包括阳极基板，结合在阳极基板上的量子点发光层。在一些实施例中，预制器件基板还包括设置在阳极基板和量子点发光层之间的空穴功能层。其中，空穴功能层包括空穴传输层、空穴注入层和电子阻挡层中的至少一种。
在一种可能的实施方式中，量子点发光二极管为倒置量子点发光二极管，预制器件基板为阴极基板。在一些实施例中，预制器件基板还包括结合在阴极基板的阴极表面的电子注入层。
在一些实施例中，第一电子传输层可以单独作为电子传输层。
在一些实施例中，电子传输层包括两层氧化锌薄膜或包括n个由两层氧化锌薄膜组成的薄膜叠层单元，两层氧化锌薄膜分别命名为第一电子传输层和第二电子传输层，n大于或等于2。在一些实施例中，n为大于或等于2且小于或等于9的整数。其中，至少第一电子传输层为上述方法制备的表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜，第二电子传输层的情形，可以参考上文量子点发光二极管器件第二电子传输层中的情形。
在一些实施例中，第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜，或第二电子传输层为金属掺杂氧化锌薄膜。其中，第一电子传输层可以设置在邻近量子点发光层的一侧，也可以设置在邻近阴极的一侧。优选的，第二电子传输层设置在邻近量子点发光层的一侧或金属掺杂氧化锌薄膜设置在邻近量子点发光层的一侧，可以得到更加平整的氧化锌薄膜。
在一些实施例中，电子传输层包括三层氧化锌薄膜，三层氧化锌薄膜分别命名为第一电子传输层、第二电子传输层和第三电子传输层。其中，至少第一电子传输层为上述方法制备的表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜，第二电子传输层和第三电子传输层的情形，可以参考上文量子点发光二极管器件中电子传输层包含第三电子传输层的情形。
本申请实施例中，表面羟基量大于或等于0.6的氧化锌薄膜的制备方法可参考上文。
在一些实施例中，上述表面羟基量小于或等于0.4的氧化锌薄膜的制备方法，包括：
将锌盐溶液与碱液混合反应，制备氧化锌纳米颗粒；将氧化锌纳米颗粒溶解，得到氧化锌胶体溶液； 向氧化锌胶体溶液加入酸液，调节氧化锌胶体溶液的pH为7～8，得到氧化锌溶液；
在待制备表面羟基量小于或等于0.4的氧化锌薄膜的预制器件基板上形成氧化锌溶液，去除溶剂，制得表面羟基量小于或等于0.4的氧化锌薄膜。
在一些实施例中，在氧化锌胶体溶液加入酸液，调节氧化锌胶体溶液的pH为7～8的步骤中，向氧化锌胶体溶液加入酸液，使得到的混合溶液的pH值在7.2～7.8之间。
在一些实施例中，在氧化锌胶体溶液加入酸液，调节氧化锌胶体溶液的pH为7～8的步骤中，向氧化锌胶体溶液加入酸液，使得到的混合溶液的pH值在7.3～7.6之间。
在一些实施例中，酸液中的酸选自盐酸、硫酸、硝酸、氢氟酸、甲酸、乙酸、丙酸、乙二酸、丙烯中的至少一种。
在一些实施例中，碱液选自氢氧化钾、氢氧化钠、氢氧化锂、TMAH、氨水、乙醇胺、乙二胺中的至少一种形成的碱液。
在一些实施例中，锌盐溶液中的溶剂、碱液中的溶剂中的溶剂各自独立地选自水、有机醇、有机醚、砜中的至少一种。
在一些实施例中，酸液中的溶剂选自水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。
在一些实施例中，表面羟基量小于或等于0.4的氧化锌薄膜为金属掺杂氧化锌薄膜，且锌盐溶液中还含有掺杂金属离子。
上述实施例中，金属掺杂氧化锌薄膜，如上文所述，为了节约篇幅，此处不再赘述。
应当理解，本申请上述两种实施方式中，当器件为正置量子点发光二极管时，在制备电子传输层之后，还包括在电子传输层上蒸镀阴极，得到量子点发光二极管。在一些实施例中，在蒸镀阴极之前，还包括在电子传输层上制备电子注入层。当器件为倒置量子点发光二极管时，在制备电子传输层之后，还包括在电子传输层上制备两点发光层，在量子点发光层上蒸镀阳极，得到量子点发光二极管。在一些实施例中，在蒸镀阳极之前，还包括在量子点发光层上制备空穴功能层。
本申请实施例中，空穴功能层(包括空穴注入层、空穴传输层和电子阻挡层中的至少一层)、量子点发光层的形成方法，优选采用溶液加工法，包括但不局限于旋涂法、刮涂法、印刷法、喷涂法、滚涂法、电沉积法等中的一种。
本申请上述实施方式中，将制备得到的量子点发光二极管进行封装处理，封装处理可采用常用的机器封装，也可以采用手动封装。优选的，封装处理的环境中，氧含量和水含量均低于0.1ppm，以保证器件的稳定性。封装所采用的固化树脂为丙烯酸类树脂、丙烯酸酯类树脂或环氧类树脂；树脂固化采用UV照射、加热或两者的结合。
在一些实施例中，根据量子点发光二极管器件的性能需求，将制备得到的量子点发光二极管进行封装处理后，还包括在对得到的量子点发光二极管进行紫外照射、加热、正负压力、外加电场、外加磁场在内的一种或多种处理，以改善量子点发光二极管器件一方面或多方面的性能，其中，施加工艺时的气氛可以为空气或惰性气氛。
下面结合具体实施例进行说明。
首先介绍本申请实施例用到的三种检测方法：
(1)X射线光电子能谱技术(X-ray photoelectron spectroscopy，简称XPS)是一种表面分析方法，使用一定能量的X射线去辐射样品，使原子或分子的内层电子或价电子受激发射出来，被光子激发出来的电子称为光电子，可以测量光电子的能量和数量，从而获得待测物组成。采用该技术可有效区分氧化锌材料存在有三种化学状态的氧，分别为与金属原子相连的晶格氧，晶体生长中形成的氧缺陷以及羟基氧。利用X射线光电子能谱(XPS)进行表面羟基测试时，设备型号：赛默飞NEXSA，样品制备方法：将制备好的氧化锌溶液稀释至30mg/mL，旋涂至预处理好的玻璃片上，旋涂成膜。其中，羟基量计算方法：羟基氧峰面积与晶格氧峰面积之比即为羟基含量比例：
Figure PCTCN2021143433-appb-000006
如图11所示。
(2)JVL(电流密度-电压-亮度)设备外量子效率测试方法
设备型号：Keithley 2400/6485
外量子效率参数主要包括六个参数：电压，电流，亮度，外量子点效率，功率效率以及发光光谱；在暗盒中对器件进行一定的电压输出使器件导电发光并记录及时电流，并通过硅光二极管对光源进行采集，分析光谱数据，得到色坐标的同时即可计算出G(λ)人眼明视觉函数以及S(λ)归一化的电致发光光谱，所以电流效率η A的计算方法为：
Figure PCTCN2021143433-appb-000007
其中，L为硅光二极管读出的亮度，JD为器件电流密度，为器件面积(a)与流经器件电流(I)的比值。
外量子效率ηEQE的计算方法为：
Figure PCTCN2021143433-appb-000008
其中，q为基本电荷，h为普朗克常量，c为真空中光速。
如从实施例图示12中读出，即为EQE-亮度曲线的EQE最高值，即为该器件的外量子效率。
(3)QLED寿命测试系统
型号：新视界NVO-QLED-LT-128
工作原理：
128路QLED寿命测试系统通过中央处理计算机的PCI总线通信，控制NI(美国国家仪器)的数字IO卡实现路数的片选以及数字信号的输出，相应的数字信号通过D/A芯片转换为模拟信号，完成电流输出(I)，并通过数据采集卡实现数据采集。亮度的采集通过传感器将光信号转换为电信号，利用电信号模拟亮度变化(L)。
测试方法：
QLED寿命测试方法(恒流法)
(A)选择三到四个不同的恒定电流密度，(比如100mA cm^2、50mA cm^2、20mA cm^2、10mA cm^2)，测试在相应条件下的起始亮度。
(B)维持恒定电流，记录亮度和器件电压随时间的变化。
(C)记录在不同恒定电流下去器件衰减到T95,T80,T75,T50的时间。
(D)通过曲线拟合计算加速因子。
(E)通过经验公式外推器件1000nit T95,T80,T75,T50的寿命，如图示13。
计算方法：T T95@1000nits＝(L MAX/1000)^A*T 95
其中：L MAX-------最高亮度
A-------加速因子
T 95------器件最高亮度衰减至95％时所经历的时间。
实施例1
一种量子点发光二极管，包括相对设置的阳极基板和阴极，设置在阳极和阴极之间的量子点发光层，设置在阳极和量子点发光层之间的空穴传输层，设置在阳极和空穴传输层之间的空穴注入层，设置在量子点发光层和阴极之间的电子传输层，其中，阳极为ITO(55nm)，空穴注入层为空穴注入层为PEDOT:PSS(50nm)，空穴传输层为TFB(30nm)，量子点发光层为红色量子点Cd xZn 1-xSe/ZnSe(40nm)，电子传输层为下述方法制得的ZnO材料(50nm)，阴极为Ag电极(100nm)。
上述量子点发光二极管的制备方法，包括：
在阳极基板上依次制备空穴注入层、空穴传输层和量子点发光层；
在量子点发光层上制备电子传输层；
蒸镀或者溅射顶电极于氧化锌电子传输层或者掺杂氧化锌电子传输层上，得到量子点发光二极管；
其中，电子传输层的制备方法为：
步骤一、
(A)将醋酸锌在室温下溶解在二甲基亚砜中配置成浓度为0.6mol/L的锌盐溶液，将氢氧化钠在室温下溶解在甲醇中，得到浓度为0.96mol/L的碱液，氢氧根离子与锌离子的摩尔比为1.6:1的比例；
(B)将锌盐溶液的温度调整至40℃，并按照氢氧根离子与锌离子的摩尔比为1.6:1的比例将碱液滴加入锌盐溶液中，随后在反应温度保持为40℃的情况下将混合溶液持续搅拌，反应90min；
(C)向反应结束后的混合溶液中加入体积比为4.5：1的沉淀剂后，混合溶液中产生白色沉淀。
(D)将得到的白色沉淀物溶解，向氧化锌胶体溶液加入浓度为0.2mol/L的氢氧化钾溶液，调节溶液的pH为8，得到羟基含量为0.85的氧化锌胶体溶液。
步骤二、在量子点发光层上形成氧化锌胶体溶液，去除溶剂，制得表面羟基量为0.85的氧化锌薄膜即电子传输层，氧化锌薄膜的厚度为50nm。
利用X射线光电子能谱(XPS)对制电子传输层的氧化锌中的羟基进行检测，测定电子传输层的羟基含量为0.85。
对比例1
与实施例1的不同之处在于：采用市售普通氧化锌纳米颗粒作为电子传输层材料。利用X射线光电子能谱(XPS)对制电子传输层的氧化锌中的羟基进行检测，测定电子传输层的羟基含量为0.5。
实施例1和对比例1提供的量子点发光二极管的器件寿命测试结果如图14所示。
实施例2
一种量子点发光二极管，包括相对设置的阳极基板和阴极，设置在阳极和阴极之间的量子点发光层，设置在阳极和量子点发光层之间的空穴传输层，设置在阳极和空穴传输层之间的空穴注入层，设置在量子点发光层和阴极之间的电子传输层，其中，阳极为ITO(55nm)，空穴注入层为空穴注入层为PEDOT:PSS(50nm)，空穴传输层为TFB(30nm)，量子点发光层为红色量子点Cd xZn 1-xSe/ZnSe(40nm)，电子传输层为下述方法制得的ZnO材料，阴极为Ag电极(100nm)。
上述量子点发光二极管的制备方法，包括：
在阳极基板上依次制备空穴注入层、空穴传输层和量子点发光层；
在量子点发光层上制备电子传输层；
蒸镀或者溅射顶电极于氧化锌电子传输层或者掺杂氧化锌电子传输层上，得到量子点发光二极管；
其中，电子传输层的制备方法为：
(1)、(A)将醋酸锌在室温下溶解在二甲基亚砜中配置成浓度为0.5mol/L的锌盐溶液，将氢氧化钾在室温下溶解在甲醇中，得到浓度为0.85mol/L的碱液，氢氧根离子与锌离子的摩尔比为1.7:1的比例；
(B)将锌盐溶液的温度调整至60℃，并按照氢氧根离子与锌离子的摩尔比为1.7:1的比例将碱液滴加入锌盐溶液中，随后在反应温度保持为60℃的情况下将混合溶液持续搅拌，反应90min；
(C)向反应结束后的混合溶液中加入体积比为3：1的沉淀剂后，混合溶液中产生白色沉淀。
(D)将得到的白色沉淀物溶解，得到浓度为0.6mol/L的第一氧化锌胶体溶液；
(2)、(A)将醋酸锌在室温下溶解在二甲基亚砜中配置成浓度为0.5mol/L的锌盐溶液，将氢氧化钾在室温下溶解在甲醇中，得到浓度为0.85mol/L的碱液，氢氧根离子与锌离子的摩尔比为1.7:1的比例；
(B)将锌盐溶液的温度调整至60℃，并按照氢氧根离子与锌离子的摩尔比为1.7:1的比例将碱液滴加入锌盐溶液中，随后在反应温度保持为60℃的情况下将混合溶液持续搅拌，反应90min；
(C)向反应结束后的混合溶液中加入体积比为3：1的沉淀剂后，混合溶液中产生白色沉淀。
(D)将得到的白色沉淀物溶解，向氧化锌胶体溶液加入0.05mol/L的盐酸，调节溶液的pH为7.2，得到羟基含量为0.25的第二氧化锌胶体溶液；
(3)在量子点发光层上形成第一氧化锌胶体溶液，去除溶剂，制得氧化锌预制薄膜；在氧化锌预 制薄膜表面沉积碱液，碱液为0.05mol/L的氢氧化钾溶液，且碱液的沉积量与下层氧化锌预制薄膜的重量满足：每5mg氧化锌预制薄膜，使用20μL的碱液进行处理，在温度为80℃的条件下加热30min，去除溶剂，制得表面羟基量为0.85的第一氧化锌薄膜即第一电子传输层；在第一氧化锌薄膜形成第二氧化锌胶体溶液，去除溶剂，制得表面羟基量为0.25的第二氧化锌薄膜即第二电子传输层。第一氧化锌层厚度为60nm，第二氧化锌层厚度为40nm。
利用X射线光电子能谱(XPS)对制备第一电子传输层、第二电子传输层的氧化锌中的羟基进行检测，测定第一电子传输层的羟基含量为0.85，第二电子传输层的羟基含量为0.25。
实施例2和对比例1提供的量子点发光二极管的器件EQE测试结果如图15所示，寿命测试结果如图16所示。
实施例3
一种量子点发光二极管，包括相对设置的阳极基板和阴极，设置在阳极和阴极之间的量子点发光层，设置在阳极和量子点发光层之间的空穴传输层，设置在阳极和空穴传输层之间的空穴注入层，设置在量子点发光层和阴极之间的电子传输层，其中，阳极为ITO(55nm)，空穴注入层为空穴注入层为PEDOT:PSS(50nm)，空穴传输层为TFB(30nm)，量子点发光层为红色量子点CdxZn1-xSe/ZnSe(40nm)，电子传输层为下述方法制得的ZnO材料，阴极为Ag电极(100nm)。
上述量子点发光二极管的制备方法，包括：
在阳极基板上依次制备空穴注入层、空穴传输层和量子点发光层；
在量子点发光层上制备电子传输层；
蒸镀或者溅射顶电极于氧化锌电子传输层或者掺杂氧化锌电子传输层上，得到量子点发光二极管；
其中，电子传输层的制备方法为：
(1)、(A)将醋酸锌在室温下溶解在二甲基亚砜中配置成浓度为0.5mol/L的锌盐溶液，将氢氧化钠在室温下溶解在甲醇中，得到浓度为0.85mol/L的碱液，氢氧根离子与锌离子的摩尔比为1.7:1的比例；
(B)将锌盐溶液的温度调整至60℃，并按照氢氧根离子与锌离子的摩尔比为1.7:1的比例将碱液滴加入锌盐溶液中，随后在反应温度保持为60℃的情况下将混合溶液持续搅拌，反应90min；
(C)向反应结束后的混合溶液中加入体积比为3：1的沉淀剂后，混合溶液中产生白色沉淀。采用反应溶剂甲醇对沉淀物进行清洗处理1次后，将得到的白色沉淀物溶解，得到表面羟基量为0.88的第一氧化锌胶体溶液。
(2)、(A)将醋酸锌在室温下溶解在二甲基亚砜中配置成浓度为0.5mol/L的锌盐溶液，将氢氧化钠在室温下溶解在甲醇中，得到浓度为0.85mol/L的碱液，氢氧根离子与锌离子的摩尔比为1.7:1的比例；
(B)将锌盐溶液的温度调整至60℃，并按照氢氧根离子与锌离子的摩尔比为1.7:1的比例将碱液滴加入锌盐溶液中，随后在反应温度保持为60℃的情况下将混合溶液持续搅拌，反应90min；
(C)向反应结束后的混合溶液中加入体积比为4：1的沉淀剂后，混合溶液中产生白色沉淀。
(D)将得到的白色沉淀物溶解，向氧化锌胶体溶液加入0.05mol/L的盐酸，调节溶液的pH为7.2，得到羟基含量为0.22的第二氧化锌胶体溶液。
(3)(A)将醋酸锌在室温下溶解在二甲基亚砜中配置成浓度为0.5mol/L的锌盐溶液，将氢氧化钠在室温下溶解在甲醇中，得到浓度为0.85mol/L的碱液，氢氧根离子与锌离子的摩尔比为1.7:1的比例；
(B)将锌盐溶液的温度调整至60℃，并按照氢氧根离子与锌离子的摩尔比为1.7:1的比例将碱液滴加入锌盐溶液中，随后在反应温度保持为60℃的情况下将混合溶液持续搅拌，反应90min；
(C)向反应结束后的混合溶液中加入体积比为3：1的沉淀剂后，混合溶液中产生白色沉淀。
(D)将得到的白色沉淀物溶解，向氧化锌胶体溶液加入0.05mol/L氢氧化钾溶液，调节溶液的pH为8.2，得到羟基含量为0.85的第二氧化锌胶体溶液。
(4)在量子点发光层上形成第一氧化锌胶体溶液，去除溶剂，制得表面羟基量为0.88的第一氧化 锌薄膜；在第一氧化锌薄膜形成第二氧化锌胶体溶液，去除溶剂，制得表面羟基量为0.22的第二氧化锌薄膜；在第二氧化锌薄膜形成第三氧化锌胶体溶液，去除溶剂，制得表面羟基量为0.85的第三氧化锌薄膜。第一氧化锌层厚度为30nm，第二氧化锌层厚度为60nm，第三氧化锌层厚度为30nm。
利用X射线光电子能谱(XPS)对制备得到的第一电子传输层、第二电子传输层、第三电子传输层中的羟基进行检测，测定第一电子传输层的羟基含量为0.88，第二电子传输层的羟基含量为0.22，第三电子传输层的羟基含量为0.85。
实施例3和对比例1提供的量子点发光二极管的器件EQE测试结果如图17所示，寿命测试结果如图18所示。
将上述3个实施例和对比例提供的量子点发光二极管进行性能测试，测试结果，如下表2：
表2
Figure PCTCN2021143433-appb-000009
应当理解的是，量子点发光二极管器件寿命的测试不同于量子点发光二极管器件效率的表征，器件效率测试的时间通常较短，因此表征的是QLED器件工作起始瞬时状态；而器件寿命表征的是器件持续工作并进入稳定状态后对于器件效率的保持能力，即进入稳定工作状态后器件中载流子注入平衡的情况。
实施例4
一种量子点发光二极管，包括相对设置的阳极基板和阴极，设置在阳极和阴极之间的量子点发光层，设置在阳极和量子点发光层之间的空穴传输层，设置在阳极和空穴传输层之间的空穴注入层，设置在量子点发光层和阴极之间的电子传输层，其中，阳极为ITO(55nm)，空穴注入层为空穴注入层为PEDOT:PSS(50nm)，空穴传输层为TFB(30nm)，量子点发光层为红色量子点Cd xZn 1-xSe/ZnSe(40nm)，电子传输层为下述方法制得的ZnO材料(50nm)，阴极为Ag电极(100nm)。
上述量子点发光二极管的制备方法，包括：
在阳极基板上依次制备空穴注入层、空穴传输层和量子点发光层；
在量子点发光层上制备电子传输层；
蒸镀或者溅射顶电极于氧化锌电子传输层或者掺杂氧化锌电子传输层上，得到量子点发光二极管；
其中，电子传输层的制备方法为：
(1)、(A)将二水合醋酸锌在室温下溶解在二甲基亚砜中配置成浓度为0.4mol/L的锌盐溶液，将氢氧化锂在室温下溶解在丁醇中，得到浓度为0.7mol/L的碱液，氢氧根离子与锌离子的摩尔比为1.75：1的比例；
(B)将锌盐溶液的温度调整至40℃，并按照氢氧根离子与锌离子的摩尔比为1.75:1的比例将碱液滴加入锌盐溶液中，随后加入油胺混合(0.4mol/L)，其中油胺配体的添加量满足：油胺配体与锌盐溶液中的锌盐的摩尔比为2:1，在反应温度保持为40℃的情况下将混合溶液持续搅拌，反应120min；
(C)向反应结束后的混合溶液中加入体积比为5：1的沉淀剂后，混合溶液中产生白色沉淀。
(D)将得到的白色沉淀物溶解，得到浓度为0.6mol/L的氧化锌胶体溶液；
(2)在量子点发光层上形成氧化锌胶体溶液，在温度为100℃的条件下干燥处理，制得厚度为50nm的氧化锌薄膜即电子传输层。
对比例2
与实施例4的不同之处在于：采用市售普通的氧化锌纳米颗粒作为电子传输层材料。
实施例4和对比例2提供的量子点发光二极管的器件EQE结果如图19所示。
实施例5
一种量子点发光二极管，包括相对设置的阳极基板和阴极，设置在阳极和阴极之间的量子点发光层，设置在阳极和量子点发光层之间的空穴传输层，设置在阳极和空穴传输层之间的空穴注入层，设置在量子点发光层和阴极之间的电子传输层，其中，阳极为ITO(55nm)，空穴注入层为空穴注入层为PEDOT:PSS(50nm)，空穴传输层为TFB(30nm)，量子点发光层为红色量子点Cd xZn 1-xSe/ZnSe(40nm)，电子传输层为下述方法制得的ZnO材料，阴极为Ag电极(100nm)。
上述量子点发光二极管的制备方法，包括：
在阳极基板上依次制备空穴注入层、空穴传输层和量子点发光层；
在量子点发光层上制备电子传输层；
蒸镀或者溅射顶电极于氧化锌电子传输层或者掺杂氧化锌电子传输层上，得到量子点发光二极管；
其中，电子传输层的制备方法为：
(1)、(A)将二水合醋酸锌在室温下溶解在二甲基亚砜中配置成浓度为0.4mol/L的锌盐溶液，将氢氧化锂在室温下溶解在丁醇中，得到浓度为0.7mol/L的碱液，氢氧根离子与锌离子的摩尔比为1.75：1的比例；
(B)将锌盐溶液的温度调整至40℃，并按照氢氧根离子与锌离子的摩尔比为1.75:1的比例将碱液滴加入锌盐溶液中，随后加入油酸混合(0.4mol/L)，其中油酸配体的添加量满足：油酸配体与锌盐溶液中的锌盐的摩尔比为1:1，在反应温度保持为40℃的情况下将混合溶液持续搅拌，反应120min；
(C)向反应结束后的混合溶液中加入体积比为5：1的沉淀剂后，混合溶液中产生白色沉淀。
(D)将得到的白色沉淀物溶解，得到浓度为0.6mol/L的氧化锌胶体溶液。
(2)在量子点发光层上形成氧化锌胶体溶液，在温度为100℃的条件下干燥处理，制得厚度为50nm的氧化锌薄膜即电子传输层。
实施例5和对比例2提供的量子点发光二极管的器件EQE测试结果如图20所示。
实施例6
一种量子点发光二极管，包括相对设置的阳极基板和阴极，设置在阳极和阴极之间的量子点发光层，设置在阳极和量子点发光层之间的空穴传输层，设置在阳极和空穴传输层之间的空穴注入层，设置在量子点发光层和阴极之间的电子传输层，其中，阳极为ITO(55nm)，空穴注入层为空穴注入层为PEDOT:PSS(50nm)，空穴传输层为TFB(30nm)，量子点发光层为红色量子点CdxZn1-xSe/ZnSe(40nm)，电子传输层为下述方法制得的ZnO材料，阴极为Ag电极(100nm)。
上述量子点发光二极管的制备方法，包括：
在阳极基板上依次制备空穴注入层、空穴传输层和量子点发光层；
在量子点发光层上制备电子传输层；
蒸镀或者溅射顶电极于氧化锌电子传输层或者掺杂氧化锌电子传输层上，得到量子点发光二极管；
其中，电子传输层的制备方法为：
(1)、(A)将二水合醋酸锌在室温下溶解在二甲基亚砜中配置成浓度为0.5mol/L的锌盐溶液，将氢氧化锂在室温下溶解在丁醇中，得到浓度为0.9mol/L的碱液，氢氧根离子与锌离子的摩尔比为1.8：1的比例；
(B)将锌盐溶液的温度调整至40℃，并按照氢氧根离子与锌离子的摩尔比为1.8:1的比例将碱液滴加入锌盐溶液中，随后在反应温度保持为30℃的情况下将混合溶液持续搅拌，反应80min；
(C)向反应结束后的混合溶液中加入体积比为4：1的沉淀剂后，混合溶液中产生白色沉淀。
(D)将得到的白色沉淀物溶解，得到浓度为0.6mol/L的氧化锌胶体溶液。
(2)、在量子点发光层上形成第一氧化锌胶体溶液，去除溶剂，制得氧化锌预制薄膜；在氧化锌预制薄膜表面沉积油胺溶液(0.4mol/L)，且油胺溶液的沉积量与下层氧化锌预制薄膜的重量满足：每5mg氧化锌预制薄膜，使用40μL的油胺溶液进行处理，在温度为120℃的条件下反应20min，去除溶剂，制得厚度为60nm的氧化锌薄膜即电子传输层。
实施例6和对比例2提供的量子点发光二极管的器件EQE测试结果如图21所示。
实施例7
一种量子点发光二极管，包括相对设置的阳极基板和阴极，设置在阳极和阴极之间的量子点发光层，设置在阳极和量子点发光层之间的空穴传输层，设置在阳极和空穴传输层之间的空穴注入层，设置在量子点发光层和阴极之间的电子传输层，其中，阳极为ITO(55nm)，空穴注入层为空穴注入层为PEDOT:PSS(50nm)，空穴传输层为TFB(30nm)，量子点发光层为红色量子点Cd xZn 1-xSe/ZnSe(40nm)，电子传输层为下述方法制得的ZnO材料，阴极为Ag电极(100nm)。
上述量子点发光二极管的制备方法，包括：
在阳极基板上依次制备空穴注入层、空穴传输层和量子点发光层；
在量子点发光层上制备电子传输层；
蒸镀或者溅射顶电极于氧化锌电子传输层或者掺杂氧化锌电子传输层上，得到量子点发光二极管；
其中，电子传输层的制备方法为：
(1)、(A)将二水合醋酸锌在室温下溶解在二甲基亚砜中配置成浓度为0.5mol/L的锌盐溶液，将氢氧化锂在室温下溶解在丁醇中，得到浓度为0.9mol/L的碱液，氢氧根离子与锌离子的摩尔比为1.8：1的比例；
(B)将锌盐溶液的温度调整至40℃，并按照氢氧根离子与锌离子的摩尔比为1.8:1的比例将碱液滴加入锌盐溶液中，随后在反应温度保持为30℃的情况下将混合溶液持续搅拌，反应80min；
(C)向反应结束后的混合溶液中加入体积比为4：1的沉淀剂后，混合溶液中产生白色沉淀。
(D)将得到的白色沉淀物溶解，得到浓度为0.6mol/L的氧化锌胶体溶液；
(2)、在量子点发光层上形成第一氧化锌胶体溶液，去除溶剂，制得氧化锌预制薄膜；在氧化锌预制薄膜表面沉积油酸溶液(0.4mol/L)，且油酸溶液的沉积量与下层氧化锌预制薄膜的重量满足：每5mg氧化锌预制薄膜，使用30μL的油酸溶液进行处理，在温度为120℃的条件下反应20min，去除溶剂，制得厚度为60nm的氧化锌薄膜及电子传输层。
实施例7和对比例2提供的量子点发光二极管的器件EQE测试结果如图22所示。
将上述实施例4-7和对比例2提供的量子点发光二极管器件的EQE进行测试，测试采用JVL(电流密度-电压-亮度)设备外量子效率测试方法，具体如上文所述。
4个实施例和对比例提供的量子点发光二极管的测试结果，如下表3：
表3
样品 外量子效率EQE
实施例1 12.62％
对比例1 7.09％
实施例2 11.95％
实施例3 10.58％
实施例4 13.12％
应当理解的是，量子点发光二极管器件寿命的测试不同于量子点发光二极管器件效率的表征，器件效率测试的时间通常较短，因此表征的是QLED器件工作起始瞬时状态；而器件寿命表征的是器件持续工作并进入稳定状态后对于器件效率的保持能力，即进入稳定工作状态后器件中载流子注入平衡的情况。
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 (69)

  1. 一种量子点发光二极管，其特征在于，包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层；
    其中，所述电子传输层包括第一电子传输层，且所述第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；或
    所述电子传输层含有氧化锌，且至少部分所述氧化锌的表面含有碳原子数为8-18的胺基配体和/或羧基配体。
  2. 如权利要求1所述的量子点发光二极管，其特征在于，所述电子传输层为所述第一电子传输层，且所述第一电子传输层中的氧化锌为掺杂金属或未掺杂金属的氧化锌。
  3. 如权利要求1所述的量子点发光二极管，其特征在于，当所述电子传输层含有氧化锌时，所述电子传输层包括含有氧化锌的第一电子传输层，且形成所述第一电子传输层的氧化锌表面含有碳原子数为8-18的胺基配体和/或羧基配体。
  4. 如权利要求3所述的量子点发光二极管，其特征在于，所述电子传输层为所述第一电子传输层，且形成所述第一电子传输层的氧化锌为未掺杂氧化锌或金属掺杂氧化锌。
  5. 如权利要求1至4任一项所述的量子点发光二极管，其特征在于，所述电子传输层还包括第二电子传输层，所述第二电子传输层设置在所述第一电子传输层靠近所述阴极或所述量子点发光层的一侧表面，且所述第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜或金属掺杂氧化锌。
  6. 如权利要求5所述的量子点发光二极管，其特征在于，所述电子传输层由所述第一电子传输层和所述第二电子传输层组成，且所述第二电子传输层较所述第一电子传输层更靠近所述量子点发光层。
  7. 如权利要求6所述的量子点发光二极管，其特征在于，所述电子传输层包括n个由第一电子传输层和所述第二电子传输层组成的薄膜叠层单元，其中，n大于或等于2。
  8. 如权利要求5所述的量子点发光二极管，其特征在于，所述电子传输层还包括第三电子传输层。
  9. 如权利要求8所述的量子点发光二极管，其特征在于，所述第三电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜。
  10. 如权利要求9所述的量子点发光二极管，其特征在于，所述第三电子传输层设置在所述第二电子传输层背离所述第一电子传输层的一侧表面，且所述第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜。
  11. 如权利要求9所述的量子点发光二极管，其特征在于，所述第三电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜。
  12. 如权利要求11所述的量子点发光二极管，其特征在于，所述第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜，且所述第三电子传输层设置在所述第一电子传输层背离所述第二电子传输层的一侧表面；或
    所述第二电子传输层为金属掺杂氧化锌薄膜，且所述第三电子传输层设置在所述第二电子传输层和所述第一电子传输层之间。
  13. 如权利要求9所述的量子点发光二极管，其特征在于，所述第三电子传输层为金属掺杂氧化锌薄膜。
  14. 如权利要求13所述的量子点发光二极管，其特征在于，所述第三电子传输层设置在所述第二电子传输层背离所述第一电子传输层的一侧表面。
  15. 如权利要求14所述的量子点发光二极管，其特征在于，所述第二电子传输层为表面羟基量小于或等于0.4的氧化锌薄膜。
  16. 如权利要求5所述的量子点发光二极管，其特征在于，所述第三电子传输层选自表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜，且所述第二电子传输层结合在所述第一电子传输层的一侧表面，所述第三电子传输层结合在所述第二电子传输层背离所述第一电子传输层的一侧表 面。
  17. 如权利要求所述的量子点发光二极管，其特征在于，所述碳原子数为8-18的胺基配体和/或羧基配体选自辛酸、辛胺、十二酸、十二胺、油酸、油胺中的至少一种。
  18. 如权利要求1至16任一项所述的量子点发光二极管，其特征在于，所述表面含有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌薄膜中，所述碳原子数为8-18的胺基配体和/或羧基配体与氧化锌的摩尔比为1:4～10:1。
  19. 如权利要求18所述的量子点发光二极管，其特征在于，所述表面含有碳原子数为8-18的胺基配体和/或羧基配体选自碳原子数为8-12的胺基配体和/或羧基配体，所述碳原子数为8-12的胺基配体和/或羧基配体与氧化锌的摩尔比为1:1～10:1；或
    所述表面含有碳原子数为8-18的胺基配体和/或羧基配体选自碳原子数为13-18的胺基配体和/或羧基配体，所述碳原子数为13-18的胺基配体和/或羧基配体与氧化锌的摩尔比为1:4～5:1。
  20. 如权利要求2至16任一项所述的量子点发光二极管，其特征在于，所述电子传输层的厚度为10～100nm；和/或
    所述表面羟基量大于或等于0.6的氧化锌薄膜的厚度为10-30nm；和/或
    所述第一电子传输层的厚度为10-80nm。
  21. 如权利要求5至16任一项所述的量子点发光二极管，其特征在于，所述表面羟基量小于或等于0.4的氧化锌薄膜的厚度为20-60nm；或
    所述金属掺杂氧化锌薄膜的厚度为10-30nm。
  22. 如权利要求1至21任一项所述的量子点发光二极管，其特征在于，所述量子点发光层中的量子点选自单核量子点或核壳结构量子点，且所述量子点的核和壳化合物各自独立地选自CdS、CdSe、CdTe、ZnO、ZnS、ZnSe、ZnTe、GaAs、GaP、GaSb、HgS、HgSe、HgTe、InAs、InP、InSb、AlAs、AlP、CuInS、CuInSe、以及上述物质形成的核壳结构量子点或合金结构量子点中的至少一种；和/或
    所述阳极的材料包括氧化锌、氧化铟、氧化锡、氧化铟锡、氧化铟锌、氟掺杂的氧化锡中的至少一种；和/或
    所述阴极的材料为Ag、Al、Au、Mg、Ca、Yb、Ba或者它们的合金。
  23. 如权利要求22所述的量子点发光二极管，其特征在于，所述量子点发光二极管还包括设置在所述阳极和所属量子点发光层中的空穴功能层，且所述空穴功能层至少包括空穴注入层、空穴传输层中的至少一种。
  24. 如权利要求23所述的量子点发光二极管，其特征在于，所述空穴注入层的材料选自聚(亚乙基二氧噻吩):聚苯乙烯磺酸盐(PEDOT:PSS)、HTL-1、HTL-2中的至少一种；和/或
    所述空穴传输层的材料选自4,4'-N,N'-二咔唑基-联苯、聚[(9,9'-二辛基芴-2,7-二基)-co-(4,4'-(N-(4-仲丁基苯基)二苯胺))]、聚(4-丁基苯基-二苯基胺)、4,4',4'-三(N-咔唑基)-三苯胺、聚(N-乙烯基咔唑)及其衍生物中的至少一种。
  25. 如权利要求5至16任一项所述的量子点发光二极管，其特征在于，所述金属掺杂氧化锌薄膜中的掺杂金属选自Mg 2+、Mn 2+中的至少一种；或所述金属掺杂氧化锌薄膜中的掺杂金属选自Al 3+、Y 3+、La 3+、Li +、Gd 3+、Zr 4+、Ce 4+中的至少一种。
  26. 如权利要求25所述的量子点发光二极管，其特征在于，所述掺杂金属的掺杂含量如下：
    当所述掺杂金属为Mg 2+时，所述金属掺杂氧化锌薄膜中Mg 2+的掺杂摩尔浓度为0.1％～35％；
    当所述掺杂金属为Mn 2+时，所述金属掺杂氧化锌薄膜中Mn 2+的掺杂摩尔浓度为0.1％～30％；
    当所述掺杂金属为Al 3+时，所述金属掺杂氧化锌薄膜中Al 3+的掺杂摩尔浓度为0.1％～15％；
    当所述掺杂金属为Y 3+时，所述金属掺杂氧化锌薄膜中Y 3+的掺杂摩尔浓度为0.1％～10％；
    当所述掺杂金属为La 3+时，所述金属掺杂氧化锌薄膜中La 3+的掺杂摩尔浓度为0.1％～7％；
    当所述掺杂金属为Li +时，所述金属掺杂氧化锌薄膜中Li +的掺杂摩尔浓度为0.1％～45％；
    当所述掺杂金属为Gd 3+时，所述金属掺杂氧化锌薄膜中Gd 3+的掺杂摩尔浓度为0.01％～8％；
    当所述掺杂金属为Zr 4+时，所述金属掺杂氧化锌薄膜中Zr 4+的掺杂摩尔浓度为0.1％～45％；
    当所述掺杂金属为Ce 4+时，所述金属掺杂氧化锌薄膜中Ce 4+的掺杂摩尔浓度为0.1％～10％。
  27. 一种量子点发光二极管的制备方法，其特征在于，所述量子点发光二极管包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层，其中，所述电子传输层包括第一电子传输层，且所述第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；
    所述表面羟基量大于或等于0.6的氧化锌薄膜的制备方法，包括：
    将锌盐溶液与第一碱液混合反应，反应结束后向混合溶液中加入沉淀剂，收集沉淀物；采用反应溶剂对所述沉淀物进行清洗处理两次或两次以下后，将得到的白色沉淀物溶解，得到氧化锌胶体溶液；
    在待制备所述表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上形成所述氧化锌胶体溶液，去除溶剂，制得表面羟基量大于或等于0.6的氧化锌薄膜。
  28. 如权利要求27所述的量子点发光二极管的制备方法，其特征在于，所述第一碱液中的碱选自K b＞10 -1的碱，所述清洗处理的次数小于或等于2次；
    所述第一碱液中的碱选自K b＜10 -1的碱，所述清洗处理的次数小于或等于1次。
  29. 如权利要求28所述的量子点发光二极管的制备方法，其特征在于，所述K b＞10 -1的碱选自氢氧化钾、氢氧化钠、氢氧化锂中的至少一种，所述K b＜10 -1的碱选自TMAH、氨水、乙醇胺、乙二胺中的至少一种。
  30. 如权利要求29所述的量子点发光二极管的制备方法，其特征在于，所述反应溶剂选自水、有机醇、有机醚、砜中的至少一种。
  31. 如权利要求30所述的量子点发光二极管的制备方法，其特征在于，所述反应溶剂选自水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。
  32. 如权利要求27至31任一项所述的量子点发光二极管的制备方法，其特征在于，所述锌盐溶液与第一碱液混合的步骤中，按照氢氧根离子与锌离子的摩尔比为1.5:1～2.5:1的比例，将所述锌盐溶液与所述第一碱液混合处理。
  33. 如权利要求27至31任一项所述的量子点发光二极管的制备方法，其特征在于，所述表面羟基量大于或等于0.6的氧化锌薄膜为金属掺杂氧化锌薄膜，且所述锌盐溶液中还含有掺杂金属离子。
  34. 一种量子点发光二极管的制备方法，其特征在于，所述量子点发光二极管包括所述量子点发光二极管包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层，其中，所述电子传输层包括第一电子传输层，且形成所述第一电子传输层的氧化锌表面含有碳原子数为8-18的胺基配体和/或羧基配体；
    所述第一电子传输层的制备方法为：
    采用锌盐溶液、碱液和碳原子数为8-18的胺基配体和/或羧基配体作为原料，通过溶液法制备氧化锌胶体溶液；其中，所述氧化锌溶液中的氧化锌表面结合有碳原子数为8-18的胺基配体和/或羧基配体；
    在待制备所述第一电子传输层的预制器件基板上形成氧化锌胶体溶液，去除溶剂，制得第一电子传输层。
  35. 如权利要求34所述的量子点发光二极管的制备方法，其特征在于，所述通过溶液法制备氧化锌胶体溶液的步骤，包括：
    将所述锌盐溶液、所述碱液和所述碳原子数为8-18的胺基配体和/或羧基配体混合反应，制备表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒；
    将所述氧化锌纳米颗粒溶解，得到氧化锌胶体溶液。
  36. 如权利要求34所述的量子点发光二极管的制备方法，其特征在于，所述通过溶液法制备氧化锌胶体溶液的步骤，包括：
    将所述锌盐溶液与所述碱液混合反应，在反应过程中加入所述碳原子数为8-18的胺基配体和/或羧基配体，制备表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒；其中，加入所述碳原子数为8-18的胺基配体和/或羧基配体后的反应时间大于或等于10分钟；
    将所述氧化锌纳米颗粒溶解，得到氧化锌胶体溶液。
  37. 如权利要求34所述的量子点发光二极管的制备方法，其特征在于，所述通过溶液法制备氧化锌胶体溶液的步骤，包括：
    将锌盐溶液与碱液混合反应制得氧化锌纳米颗粒后，加入所述碳原子数为8-18的胺基配体和/或羧基配体，继续反应，制备制备表面结合有碳原子数为8-18的胺基配体和/或羧基配体的氧化锌纳米颗粒；
    将所述氧化锌纳米颗粒溶解，得到氧化锌胶体溶液。
  38. 如权利要求34所述的量子点发光二极管的制备方法，其特征在于，所述通过溶液法制备氧化锌胶体溶液的步骤，包括：
    将锌盐溶液与碱液混合反应，收集产物清洗处理，得到氧化锌纳米颗粒；
    将所述氧化锌纳米颗粒溶解后，加入碳原子数为8-18的胺基配体和/或羧基配体反应，在氧化锌表面结合碳原子数为8-18的胺基配体和/或羧基配体，得到氧化锌胶体溶液。
  39. 如权利要求34至38任一项所述的量子点发光二极管的制备方法，其特征在于，加入碳原子数为8-18的胺基配体和/或羧基配体后，反应10分钟-2小时。
  40. 如权利要求34至38任一项所述的量子点发光二极管的制备方法，其特征在于，所述碳原子数为8-18的胺基配体和/或羧基配体为配体溶液，且所述配体溶液的浓度为0.2-0.4mmol/L。
  41. 如权利要求40所述的量子点发光二极管的制备方法，其特征在于，所述碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：所述碳原子数为8-18的胺基配体和/或羧基配体与所述锌盐溶液中的锌盐的摩尔比为1:1～10:1。
  42. 如权利要求41所述的量子点发光二极管的制备方法，其特征在于，所述胺基配体和/或羧基配体的碳原子数为8-12，且所述胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与所述锌盐溶液中的锌盐的摩尔比为4:1～10:1；
    所述胺基配体和/或羧基配体的碳原子数为13-18，且所述胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与所述锌盐溶液中的锌盐的摩尔比为1:1～5:1。
  43. 如权利要求39所述的量子点发光二极管的制备方法，其特征在于，所述碳原子数为8-18的胺基配体和/或羧基配体为配体溶液，且所述配体溶液的浓度为0.05-0.1mmol/L。
  44. 如权利要求43所述的量子点发光二极管的制备方法，其特征在于，所述碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：所述碳原子数为8-18的胺基配体和/或羧基配体与所述锌盐溶液中的锌盐的摩尔比为1:4～4:1。
  45. 如权利要求44所述的量子点发光二极管的制备方法，其特征在于，所述胺基配体和/或羧基配体的碳原子数为8-12，且所述胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与所述锌盐溶液中的锌盐的摩尔比为1:1～10:1；
    所述胺基配体和/或羧基配体的碳原子数为13-18，且所述胺基配体和/或羧基配体的添加量满足：胺基配体和/或羧基配体与所述锌盐溶液中的锌盐的摩尔比为1:4～5:1。
  46. 如权利要求35至38任一项所述的量子点发光二极管的制备方法，其特征在于，所述碳原子数为8-18的胺基配体和/或羧基配体选自辛酸、辛胺、十二酸、十二胺、油酸、油胺中的至少一种。
  47. 一种量子点发光二极管的制备方法，其特征在于，所述量子点发光二极管包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层，其中，所述电子传输层包括含有氧化锌的第一电子传输层，且至少第一电子传输层的一侧表面含有碳原子数为8-18的胺基配体和/或羧基配体；
    其中，第一电子传输层的制备方法，包括：
    在待制备第一电子传输层的预制器件基板上制备氧化锌预制薄膜；
    在氧化锌预制薄膜的表面沉积碳原子数为8-18的胺基配体和/或羧基配体溶液后进行干燥处理，得到氧化锌薄膜。
  48. 如权利要求47所述的量子点发光二极管的制备方法，其特征在于，所述碳原子数为8-18的胺 基配体和/或羧基配体溶液的浓度为0.05-0.1mmol/L。
  49. 如权利要求48所述的量子点发光二极管的制备方法，其特征在于，所述碳原子数为8-18的胺基配体和/或羧基配体的碳原子为8-12，且所述碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：每5mg氧化锌预制薄膜，沉积碳原子数为8-12的胺基配体和/或羧基配体溶液100μL-500μL。
  50. 如权利要求48所述的量子点发光二极管的制备方法，其特征在于，所述碳原子数为8-18的胺基配体和/或羧基配体的碳原子为13-18，且所述碳原子数为8-18的胺基配体和/或羧基配体的添加量满足：每5mg氧化锌预制薄膜，沉积碳原子数为13-18的胺基配体和/或羧基配体溶液50μL-300μL。
  51. 如权利要求47至50任一项所述的量子点发光二极管的制备方法，其特征在于，所述碳原子数为8-18的胺基配体和/或羧基配体选自丙酸、丙胺、丁酸、丁胺、己酸、己胺中的至少一种。
  52. 如权利要求47至50任一项所述的量子点发光二极管的制备方法，其特征在于，所述干燥处理的温度为10℃～100℃，干燥时间为10分钟～2小时。
  53. 一种量子点发光二极管的制备方法，其特征在于，所述量子点发光二极管包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层，其中，所述电子传输层包括第一电子传输层，且所述第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；
    所述表面羟基量大于或等于0.6的氧化锌薄膜的制备方法，包括：
    将锌盐溶液与第一碱液混合反应，制备氧化锌；将所述氧化锌溶解，得到氧化锌胶体溶液；向所述氧化锌胶体溶液加入第二碱液，调节所述氧化锌胶体溶液的pH大于或等于8，得到氧化锌溶液；
    在待制备所述表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上形成氧化锌溶液，去除溶剂，制得表面羟基量大于或等于0.6的氧化锌薄膜。
  54. 如权利要求53所述的量子点发光二极管的制备方法，其特征在于，所述在所述氧化锌胶体溶液加入第二碱液，调节所述氧化锌胶体溶液的pH大于或等于8的步骤中，向所述氧化锌胶体溶液加入第二碱液，使得到的混合溶液的pH值为9～12。
  55. 如权利要求54所述的量子点发光二极管的制备方法，其特征在于，所述在所述氧化锌胶体溶液加入第二碱液，调节所述氧化锌胶体溶液的pH大于或等于8的步骤中，向所述氧化锌胶体溶液加入第二碱液，使得到的混合溶液的pH值为9～10。
  56. 如权利要求53所述的量子点发光二极管的制备方法，其特征在于，所述第二碱液中的碱选自氢氧化钾、氢氧化钠、氢氧化锂、TMAH、氨水、乙醇胺、乙二胺中的至少一种。
  57. 如权利要求53至56任一项所述的量子点发光二极管的制备方法，其特征在于，所述第一碱液选自氢氧化钾、氢氧化钠、氢氧化锂、TMAH、氨水、乙醇胺、乙二胺中的至少一种形成的第一碱液。
  58. 如权利要求53至56任一项所述的量子点发光二极管的制备方法，其特征在于，所述锌盐溶液中的溶剂、所述第一碱液中的溶剂中的溶剂各自独立地选自水、有机醇、有机醚、砜中的至少一种。
  59. 如权利要求53至56任一项所述的量子点发光二极管的制备方法，其特征在于，所述第二碱液中的溶剂选自水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、DMSO中的至少一种。
  60. 如权利要求53至56任一项所述的量子点发光二极管的制备方法，其特征在于，所述表面羟基量大于或等于0.6的氧化锌薄膜为金属掺杂氧化锌薄膜，且所述锌盐溶液中还含有掺杂金属离子。
  61. 一种量子点发光二极管的制备方法，其特征在于，所述量子点发光二极管包括相对设置的阳极和阴极，设置在所述阳极和所述阴极之间的量子点发光层，设置在所述量子点发光层和所述阴极之间的电子传输层，其中，所述电子传输层包括第一电子传输层，所述第一电子传输层为表面羟基量大于或等于0.6的氧化锌薄膜；
    所述表面羟基量大于或等于0.6的氧化锌薄膜的制备方法，包括：
    在待制备所述表面羟基量大于或等于0.6的氧化锌薄膜的预制器件基板上制备氧化锌预制薄膜；
    在所述氧化锌预制薄膜的表面沉积第二碱液后进行干燥处理，得到氧化锌薄膜。
  62. 如权利要求61所述的量子点发光二极管的制备方法，其特征在于，所述第二碱液选自氢氧化钾、氢氧化钠、氢氧化锂、TMAH、氨水、乙醇胺、乙二胺中的至少一种形成的碱液。
  63. 如权利要求62所述的量子点发光二极管的制备方法，其特征在于，所述第二碱液的浓度为0.05-0.5mmol/L。
  64. 如权利要求63所述的量子点发光二极管的制备方法，其特征在于，所述第二碱液中的碱为无机碱，且所述第二碱液的浓度为0.05-0.1mmol/L。
  65. 如权利要求64所述的量子点发光二极管的制备方法，其特征在于，所述在所述氧化锌预制薄膜的表面沉积第二碱液的步骤中，所述第二碱液的添加量满足：每5mg氧化锌预制薄膜，使用50μL-400μL的第二碱液进行处理。
  66. 如权利要求63所述的量子点发光二极管的制备方法，其特征在于，所述第二碱液中的碱为有机碱，且所述第二碱液的浓度为0.2-0.4mmol/L。
  67. 如权利要求66所述的量子点发光二极管的制备方法，其特征在于，所述在所述氧化锌预制薄膜的表面沉积第二碱液的步骤中，所述第二碱液的添加量满足：每5mg氧化锌预制薄膜，使用500μL-1000μL的第二碱液进行处理。
  68. 如权利要求61至67任一项所述的量子点发光二极管的制备方法，其特征在于，所述干燥处理的温度为10℃～100℃，干燥时间为10分钟～2小时。
  69. 如权利要求61至67任一项所述的量子点发光二极管的制备方法，其特征在于，所述表面羟基量大于或等于0.6的氧化锌薄膜为金属掺杂氧化锌薄膜。
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