WO2022143556A1 - 光电器件 - Google Patents

光电器件 Download PDF

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WO2022143556A1
WO2022143556A1 PCT/CN2021/141746 CN2021141746W WO2022143556A1 WO 2022143556 A1 WO2022143556 A1 WO 2022143556A1 CN 2021141746 W CN2021141746 W CN 2021141746W WO 2022143556 A1 WO2022143556 A1 WO 2022143556A1
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layer
hole transport
quantum dot
energy level
hole
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PCT/CN2021/141746
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English (en)
French (fr)
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杨一行
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Tcl科技集团股份有限公司
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Priority to US18/270,719 priority Critical patent/US20240107791A1/en
Publication of WO2022143556A1 publication Critical patent/WO2022143556A1/zh

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    • H—ELECTRICITY
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    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H10K50/115—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising active inorganic nanostructures, e.g. luminescent quantum dots
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F3/00—Compounds containing elements of Groups 2 or 12 of the Periodic Table
    • C07F3/06—Zinc compounds
    • C—CHEMISTRY; METALLURGY
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    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/88—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing selenium, tellurium or unspecified chalcogen elements
    • C09K11/881—Chalcogenides
    • C09K11/883—Chalcogenides with zinc or cadmium
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    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/14—Carrier transporting layers
    • H10K50/15—Hole transporting layers
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    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/14—Carrier transporting layers
    • H10K50/16—Electron transporting layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H—ELECTRICITY
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    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/30—Coordination compounds
    • H10K85/381—Metal complexes comprising a group IIB metal element, e.g. comprising cadmium, mercury or zinc
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
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    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/30—Highest occupied molecular orbital [HOMO], lowest unoccupied molecular orbital [LUMO] or Fermi energy values
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/40—Interrelation of parameters between multiple constituent active layers or sublayers, e.g. HOMO values in adjacent layers
    • H—ELECTRICITY
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    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2102/00—Constructional details relating to the organic devices covered by this subclass
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2102/00—Constructional details relating to the organic devices covered by this subclass
    • H10K2102/301—Details of OLEDs
    • H10K2102/331—Nanoparticles used in non-emissive layers, e.g. in packaging layer

Definitions

  • the present application relates to the field of display technology, in particular to an optoelectronic device.
  • QLED Quantum dot light-emitting display technology
  • OLED organic light-emitting display
  • QLED is an active light-emitting technology, so it also has high luminous efficiency, fast response speed, high contrast, Wide viewing angle and other advantages.
  • QLED Due to the excellent material properties of quantum dots in QLED display technology, QLED has performance advantages over OLED in many aspects, such as: the emission of quantum dots is continuously adjustable and the emission width is extremely narrow, which can achieve a wider color gamut and higher Purity display; the inorganic material characteristics of quantum dots make QLED have better device stability; the driving voltage of QLED device is lower than that of OLED, which can achieve higher brightness and reduce energy consumption; at the same time, QLED display technology and printing display production process and The matching technology can realize the high-efficiency mass production preparation of large size, low cost, and rollability. Therefore, QLED is considered to be one of the preferred technologies for next-generation display screens that are thin, portable, flexible, transparent and high-performance in the future.
  • the device structure of QLED is more borrowed from OLED display technology, except that the light-emitting layer material is replaced by organic light-emitting material.
  • other functional layer materials such as charge injection layer or charge transport layer, often use existing materials in OLEDs.
  • the explanation of device physics in QLED devices, the selection and collocation of energy levels of functional layer materials, etc. also follow the existing theoretical system in OLED.
  • the application of the classical device physics conclusions obtained in the research of OLED devices to the QLED device system has indeed significantly improved the performance of QLED devices, especially the efficiency of QLED devices.
  • One of the purposes of the embodiments of the present application is to provide an optoelectronic device, which aims to solve the problem that it is difficult to simultaneously improve the optoelectronic efficiency and lifetime performance of the QLED device in the related art.
  • An electrical device comprising: an anode, a hole transport layer on the anode, a quantum dot light emitting layer on the hole transport layer, an electron transport layer on the quantum dot light emitting layer, and A cathode on the electron transport layer; wherein, the quantum dot light-emitting layer includes a core-shell structure quantum dot material, and the outer shell layer material of the quantum dot material has a valence of the hole transport material in the hole transport layer.
  • the band top energy level difference is greater than or equal to 0.5 eV; the electron transport layer contains zinc oxide nanomaterials, and the surface of the zinc oxide nanomaterials is bound with amine group/carboxyl group ligands with a chain length of 3-8 carbon atoms.
  • a valence band top energy level difference greater than or equal to 0.5 eV is constructed between the outer shell layer material of the quantum dot material and the hole transport material, that is, E EML-HTL ⁇ 0.5eV.
  • the hole injection efficiency is reduced by increasing the hole injection barrier, thereby balancing the injection balance of holes and electrons in the light-emitting layer.
  • zinc oxide nanomaterials with amine/carboxyl ligands with a chain length of 3 to 8 carbon atoms bound to the surface in the electron transport layer, and amine group/carboxyl ligands with a chain length of 3 to 8 carbon atoms are replaced
  • the hydroxyl ligands on the surface of zinc oxide colloid can effectively reduce the content of negatively charged hydroxyl groups on the surface of zinc oxide nanomaterials, reduce the electronegativity of zinc oxide nanomaterials, thereby reducing the inhibition of negatively charged hydroxyl groups on electron transport and It can hinder the effect and improve the efficiency of electron transfer and injection.
  • the chain length of amine/carboxyl ligands is 3-8 carbon atoms, the chain length is short, the steric hindrance effect is small, and the distance between ZnO nanoparticles and the inter-nanoparticles in the electron transport layer film will not be increased.
  • electron transfer efficiency The injection rate of holes and electrons in the light-emitting device is balanced, the recombination efficiency of electrons and holes is improved, the charge accumulation caused by unbalanced carrier injection is avoided, and the light-emitting efficiency and service life of the light-emitting device are improved.
  • FIG. 1 is a schematic structural diagram of the optoelectronic device provided by the first aspect of the embodiment of the present application;
  • FIG. 2 is a schematic diagram of a positive structure of a quantum dot light-emitting diode provided by an embodiment of the present application
  • FIG. 3 is a schematic diagram of an inversion structure of a quantum dot light-emitting diode provided by an embodiment of the present application.
  • At least one means one or more
  • plural items means two or more.
  • At least one item(s) below” or similar expressions thereof refer to any combination of these items, including any combination of single item(s) or plural items(s).
  • at least one (one) of a, b, or c or, “at least one (one) of a, b, and c” can mean: a,b,c,a-b( That is, a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple respectively.
  • ⁇ E HTL-HIL E HOMO,HTL -E HIL
  • ⁇ E EML-HTL E HOMO,EML -E HTL
  • all energy level/work function values are absolute values, and the absolute value of the energy level is large The energy level is deep, and the absolute value of the energy level is small, the energy level is shallow.
  • the amount of hydroxyl groups on the surface of the zinc oxide film is measured by X-ray photoelectron spectroscopy (XPS). Specifically: the zinc oxide film is detected, and the O1s energy spectrum in the result can be divided into three sub-peaks by peaks. are the OM peak representing the molar concentration of oxygen atoms in the zinc oxide crystal (peak position is between 529ev-531ev), the OV peak representing the oxygen vacancy molar concentration in the zinc oxide crystal (peak position is between 531ev-532ev), representing the oxidation The OH peak of the molar concentration of hydroxyl ligands on the surface of zinc crystals (peak position is between 532ev-534ev).
  • XPS X-ray photoelectron spectroscopy
  • the area ratio between each sub-peak represents the ratio of the molar concentration of different kinds of oxygen atoms in the zinc oxide film. Therefore, the amount of hydroxyl groups on the surface of the zinc oxide film is defined as "OH peak area/OM peak area", that is, the surface of the zinc oxide film is defined.
  • the amount of hydroxyl groups the molar concentration of hydroxyl ligands on the surface of the zinc oxide film/the molar concentration of oxygen atoms in the zinc oxide crystal.
  • the key of this application is to simultaneously improve the lifetime and photoelectric efficiency of QLED devices.
  • the time of device efficiency test is usually short, so it characterizes the instantaneous state of the QLED device at the beginning of operation; while the device life characterizes the continuous operation of the device and enters into a stable state The ability to maintain device efficiency after state.
  • the injection rate of electrons into the light-emitting layer is usually faster than that of holes. Therefore, in order to balance and improve the recombination efficiency of holes and electrons in the light-emitting layer of a QLED device, a hole injection layer is usually set in the device, and the injection barrier between two adjacent functional layers is minimized to enhance the hole efficiency. injection efficiency, thereby improving carrier injection efficiency and reducing interfacial charge accumulation.
  • this method can only improve the photoelectric efficiency at the initial instant of the QLED device to a certain extent, but cannot improve the device life at the same time, and even reduces the device life.
  • QLED has some special mechanisms different from the OLED device system.
  • the mechanism is closely related to the performance of QLED devices, especially the device lifetime.
  • this application finds through research that: in the initial working state of the QLED device, the injection rate of electrons in the light-emitting layer is faster than that of holes, resulting in the negative charge of the quantum dot material. Factors such as ligand binding and Coulomb blocking effects are maintained.
  • the negatively charged state of the quantum dot material makes it more and more difficult to inject electrons during the continuous operation of the QLED device, resulting in an imbalance between the actual injection of electrons and holes in the light-emitting layer.
  • the negatively charged state of the quantum dot material also tends to be stable, that is, the electrons newly captured and bound by the quantum dots reach a dynamic balance with the electrons consumed by the radiative transition.
  • the injection rate of electrons into the light-emitting layer is much lower than that in the initial state, and the hole injection rate required to achieve the balance of charge injection in the light-emitting layer is actually relatively low.
  • the hole injection efficiency is still improved based on the theoretical system of traditional OLED devices, the use of deep-level hole transport layers can only form an instantaneous balance of charge injection in the initial stage of QLED device operation, and achieve high device efficiency at the initial instant.
  • the QLED device enters a stable working state, excessive hole injection will aggravate the unbalanced state of electrons and holes in the light-emitting layer of the device, and the efficiency of the QLED device cannot be maintained, and thus decreases. And this charge imbalance will continue to increase as the device continues to work, resulting in a corresponding rapid decline in the life of the QLED device.
  • the key to fine-tuning the carrier injection of holes and electrons on both sides of the device is: on the one hand , regulate the hole injection rate to a lower rate, and improve the electron injection efficiency at the same time, so that the hole injection rate and the electron injection rate in the stable working state of the QLED device are balanced, and the recombination efficiency of the QLED device is improved.
  • the hole injection rate required for QLED devices in the actual stable operating state is lower than traditionally expected, carrier accumulation is prone to occur, causing irreversible damage to the device. Therefore, the influence of carrier accumulation on the device life should be avoided as much as possible, and the device life should be improved.
  • a first aspect of an embodiment of the present application provides an optoelectronic device, comprising: an anode, a hole transport layer on the anode, a quantum dot light-emitting layer on the hole transport layer, and a quantum dot light-emitting layer on the The electron transport layer on the electron transport layer, and the cathode on the electron transport layer; wherein, the quantum dot light-emitting layer includes a quantum dot material with a core-shell structure, the outer shell layer material of the quantum dot material and the valence band of the hole transport material in the hole transport layer.
  • the top energy level difference is greater than or equal to 0.5eV; the electron transport layer contains zinc oxide nanomaterials, and the surface of the zinc oxide nanomaterials is combined with amine group/carboxyl group ligands with a chain length of 3-8 carbon atoms.
  • a valence band top energy level difference greater than or equal to 0.5 eV is constructed between the outer shell layer material of the quantum dot material and the hole transport material, that is, E EML-HTL ⁇ 0.5 eV.
  • the hole injection efficiency is reduced by increasing the hole injection barrier, thereby balancing the injection balance of holes and electrons in the light-emitting layer.
  • zinc oxide nanomaterials with amine/carboxyl ligands with a chain length of 3 to 8 carbon atoms bound to the surface in the electron transport layer, and amine group/carboxyl ligands with a chain length of 3 to 8 carbon atoms are replaced
  • the hydroxyl ligands on the surface of zinc oxide colloid can effectively reduce the content of negatively charged hydroxyl groups on the surface of zinc oxide nanomaterials, reduce the electronegativity of zinc oxide nanomaterials, thereby reducing the inhibition of negatively charged hydroxyl groups on electron transport and It can hinder the effect and improve the efficiency of electron transfer and injection.
  • the chain length of amine/carboxyl ligands is 3-8 carbon atoms, the chain length is short, the steric hindrance effect is small, and the distance between ZnO nanoparticles and the inter-nanoparticles in the electron transport layer film will not be increased. electron transfer efficiency.
  • this application finds through research that at least an energy level barrier of ⁇ E EML-HTL ⁇ 0.5 eV is required to realize hole injection.
  • the significant reduction in efficiency balances the injection efficiency of electrons and holes in the light-emitting layer.
  • the hole injection barrier of ⁇ E EML-HTL ⁇ 0.5eV in the present application will not prevent holes from being injected, because the energy level of the outer shell of the quantum dots will be band-bended in the energized working state, and carriers can pass through.
  • the tunneling effect realizes the injection; thus, although this increase in the energy level barrier will cause a decrease in the carrier injection rate, it will not completely hinder the final injection of carriers.
  • the core material determines the luminescence performance
  • the shell material protects and facilitates carrier injection
  • electrons and holes are injected into the core through the shell layer to emit light.
  • the band gap of the inner core is narrower than that of the outer shell, so the energy level difference between the valence band of the hole transport material and the inner core of the quantum dot is smaller than the energy level difference of the valence band of the hole transport material and the outer shell of the quantum dot. Therefore, the ⁇ E EML-HTL is greater than or equal to 0.5 eV, which can simultaneously ensure the effective injection of hole carriers into the inner core of the quantum dot material.
  • the valence band top energy level difference between the outer shell layer material of the quantum dot material and the hole transport material in the hole transport layer is 0.5-1.7 eV, that is, the ⁇ E EML-HTL is 0.5 eV-1.7 eV, and the quantum dot material is 0.5-1.7 eV.
  • the energy level barrier in this range constructed between the outer shell material and the hole transport material can be applied to device systems constructed of different hole transport materials and quantum dot materials to optimize the injection of electrons and holes in different device systems. balance.
  • ⁇ E EML-HTL different top valence band energy level differences ⁇ E EML-HTL can be set according to the specific material properties, and the carrier injection rate of holes and electrons on both sides of the light-emitting layer can be finely adjusted to balance the injection of holes and electrons.
  • the valence band top energy level difference between the shell layer material of the quantum dot material and the hole transport material is 0.5eV ⁇ 0.7eV
  • the applicable hole transport materials are TFB, P12, P15
  • the quantum dot shell material For ZnSe, CdS such as: TFB-ZnSe, P12/P15-CdS and other device systems.
  • the valence band top energy level difference between the outer shell material of the quantum dot material and the hole transport material is 0.7eV ⁇ 1.0eV
  • the applicable hole transport material is TFB, P09
  • the quantum dot shell material is ZnSe , CdS, such as: P09-ZnSe, TFB-CdS and other device systems.
  • the valence band top energy level difference between the outer shell layer material of the quantum dot material and the hole transport material is 1.0eV ⁇ 1.4eV
  • the applicable hole transport materials are FB, P09, P13, P14
  • the shell materials are CdS, ZnSe, ZnS, such as: TFB-ZnS, P09-CdS, P13/P14-ZnSe and other device systems.
  • the valence band top energy level difference between the outer shell layer material of the quantum dot material and the hole transport material is greater than 1.4eV-1.7eV, and the device system of P09-ZnS and P13/P14-ZnS is applicable.
  • zinc oxide nanomaterials with amine groups/carboxyl ligands with a chain length of 3 to 8 carbon atoms bound on the surface are selected, and amine groups with a chain length of 4 to 6 carbon atoms bound on the surface are selected.
  • ZnO nanomaterials with /carboxyl ligands If the chain length of the amine/carboxyl ligand is too short, the acidity and alkalinity of the amine/carboxyl ligand will increase significantly.
  • zinc oxide nanomaterials with amine group/carboxyl group ligands with chain lengths of 3 to 8 carbon atoms bound on the surface of the examples of the present application can be prepared by a sol-gel method. During the process, add a suitable concentration of amino/carboxyl ligand compound solution with a chain length of 3-8 carbons to the zinc oxide precursor solution. ZnO nanomaterials with amine group/carboxyl group ligands of target chain length bound on the surface were obtained.
  • the exchange amount of the amine group/carboxyl group ligand on the surface of the zinc oxide nanomaterial can be flexibly regulated, thereby regulating the zinc oxide.
  • the amount of negatively charged hydroxyl groups on the nanoparticle surface can be flexibly regulated, thereby regulating the zinc oxide.
  • the zinc oxide nanomaterial is prepared by a sol-gel method according to the molar ratio of the amine group/carboxyl group ligand compound to the zinc oxide precursor of (1-10):1.
  • zinc oxide nanomaterials are prepared according to the molar ratio of the amine group/carboxyl group ligand compound to the zinc oxide precursor (1-10): 1, and the amount of hydroxyl groups on the surface of the zinc oxide nanoparticles is controlled at a low level, reducing the The negatively charged hydroxyl group inhibits and hinders electron transport and improves the efficiency of electron transfer and injection.
  • the appropriate amine/carboxyl ligand compound and zinc oxide can be selected comprehensively according to factors such as the length of the carbon chain of the target ligand, the size of steric hindrance, and the ligand exchange effect with the hydroxyl group.
  • the ratio of precursors In some specific embodiments, when the chain length of the amine/carboxyl ligand compound is 3-4 carbon atoms, the molar ratio of the amine/carboxyl ligand compound to the zinc oxide precursor is (4-10): 1. Preparation of ZnO nanomaterials.
  • the molar ratio of the amine group/carboxyl group ligand compound to the zinc oxide precursor is (1 to 5) : 1. Preparation of zinc oxide nanomaterials.
  • the amino/carboxyl ligand compound is selected from at least one of propionic acid, propylamine, butyric acid, butylamine, caproic acid, hexylamine, pentylamine, and octylamine.
  • the chain length of the amine group/carboxyl group ligand compound used in the above embodiments of the present application is 3-8 carbon atoms, and the exchange effect with the hydroxyl group ligand on the surface of the zinc oxide nanoparticle is good.
  • the zinc oxide precursor is selected from at least one of zinc acetate, zinc nitrate, zinc sulfate, and zinc chloride.
  • at room temperature at least one zinc oxide precursor selected from zinc acetate, zinc nitrate, zinc sulfate, and zinc chloride is dissolved in water, methanol, ethanol, propanol, butanol, ethylene glycol, Add potassium hydroxide, sodium hydroxide, lithium hydroxide, tetramethylammonium hydroxide TMAH, ammonia water, ethanolamine to a solvent such as ethylene glycol monomethyl ether, dimethyl sulfoxide, DMSO, etc., after the temperature is adjusted to 0 to 70 °C , ethylenediamine and other alkaline solutions, then keep stirring/reacting the mixed solution for 30min-4h while the reaction temperature is kept at 0 ⁇ 70°C, and add a precipitant to the mixed solution after the reaction for precipitation.
  • the time node of adding the amine group/carboxyl ligand compound solution with chain length of 3-8 carbons in the embodiment of the present application can be the initial stage of the synthesis of the zinc oxide colloidal solution, that is, it is added to the zinc oxide precursor solution simultaneously with the lye; It can also be added in the middle stage of zinc oxide colloidal solution synthesis, that is, added to the zinc oxide precursor solution to which alkali solution has been added; it can also be added to the solution before cleaning after the synthesis of zinc oxide colloid solution; it can also be added during cleaning After that, it is added to the final zinc oxide colloidal solution obtained. No matter at which stage the ligand solution is added, it needs to be stirred for 10min-2h after the addition, so that the reaction can be fully carried out. More preferably, the stirring time is 30min-1h.
  • the electron transport layer is a laminated composite structure, and in addition to the zinc oxide nanomaterials with surface-bound amine group/carboxyl ligands with a chain length of 3 to 8 carbon atoms, it also includes an organic transport material.
  • electron transport layer Organic transport materials can achieve energy level regulation in a wide range. Through the co-coordination of metal oxo compound transport materials and organic transport materials in the electron transport layer, the electron transport layer has both high electron mobility and energy level matching. flexibility. Effective regulation of the energy level and electron mobility of the electron transport layer is achieved, so as to achieve a sufficient match with hole injection.
  • the electron transport layer in the embodiments of the present application can be prepared into a thin film in a light-emitting device by vacuum evaporation or solution method; wherein the solution method includes inkjet printing, spin coating, jet printing, slot coating or screen printing.
  • the electron mobility of the organic transport material is not less than 10 ⁇ 4 cm 2 /Vs.
  • the organic transport material is selected from the group consisting of 8-quinolinolato-lithium, aluminum octaquinolate, fullerene derivatives, 3,5-bis(4-tert-butylphenyl)-4-phenyl -At least one of 4H-1,2,4-triazole and 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene.
  • These organic transport materials can realize energy level regulation in a wide range, which is more conducive to regulating the energy levels of each functional layer of the device and improving the stability and photoelectric conversion efficiency of the device.
  • the electron transport layer further includes a metal oxo compound transport layer, wherein the metal oxo compound is selected from at least one of titanium oxide, zinc sulfide, and cadmium sulfide. These metal oxo compound transport materials all have high electron transfer efficiency.
  • the particle size of the metal oxide transport material is less than or equal to 10 nm.
  • the metal oxide transport material with small particle size is more conducive to deposition to obtain electrons with a dense film layer and a uniform thickness.
  • the thin film of the transmission layer improves the bonding tightness with the adjacent functional layer, reduces the interface resistance, and is more conducive to improving the performance of the device.
  • the metal oxide compound transport material with small particle size has a wider band gap, which reduces the quenching of the exciton emission of the quantum dot material and improves the device efficiency.
  • the electron mobility of the metal oxo compound transport material is 10 -2 to 10 -3 cm 2 /Vs, and the electron transport material with high mobility can reduce the accumulation of charges in the interface layer, improve electron injection, compound efficiency.
  • the QLED device of the embodiment of the present application needs to regulate the hole injection rate to a lower rate in a certain way. Therefore, in some specific embodiments, the hole injection layer may not be provided in the optoelectronic device provided in the first aspect of the embodiments of the present application to enhance the hole injection efficiency.
  • the setting of the hole injection layer in the QLED device can not only improve the hole injection efficiency, but also is the key to regulating the stable and balanced injection of holes, and is also one of the key factors affecting the performance and life of the device. Therefore, in the embodiments of the present application, the hole injection efficiency in the device can also be controlled by arranging a hole injection layer in the device, and the influence of charge accumulation on the life of the device can be avoided. specifically:
  • the voltage rise of the QLED device caused at this time is significantly different from the voltage rise caused by the charge accumulation at the EML interface as follows:
  • the interface between the HIL and the HTL generates an electric field due to the charge accumulation, and the irreversible damage caused by the charge accumulation will follow the device. What happens all the time with continuous energization will continue to deteriorate; while the charge accumulation at the EML interface is reversible and will reach a certain degree of saturation. Therefore, the interfacial charge accumulation between HIL and HTL has a greater impact on the performance of the device, such as lifetime.
  • an optoelectronic device is provided on the basis of the embodiments of the first aspect.
  • the optoelectronic device includes a hole transport layer and a first hole injection layer.
  • the absolute value of the work function difference with the first hole injection material in the first hole injection layer is less than or equal to 0.2 eV.
  • the energy level barrier of hole injection between HTL and HIL can be significantly reduced, and the injection efficiency of holes from the anode can be improved, It is conducive to the effective injection of holes from HIL to HTL, eliminates potential barriers and interface charges, and reduces the overall resistance of the device, thereby avoiding irreversible damage caused by charge accumulation at the interface between HIL and HTL, reducing device driving voltage and improving device life. .
  • the absolute value of the difference between the valence band top energy level of the hole transport layer material and the work function of the first hole injection material is 0 eV.
  • the absolute value of the work function of the first hole injection material is 5.3 eV ⁇ 5.6 eV
  • the absolute value of the valence band energy level of the hole injection material with the work function size is compared with that of the existing hole transport material. Close to (about 5.4eV), it is beneficial to control
  • HIL and HTL materials with suitable energy levels so that
  • the mobility of the hole transport material is higher than 1 ⁇ 10 ⁇ 4 cm 2 /Vs.
  • hole transport materials with a mobility higher than 1 ⁇ 10 -4 cm 2 /Vs are used to ensure the transport and migration effect of holes, prevent charge accumulation, eliminate interface charges, and better reduce the device driving voltage and improve the device. life.
  • a third aspect of the embodiments of the present application provides an optoelectronic device based on the embodiments of the first aspect, comprising a hole transport layer and a second hole injection layer, wherein the hole transport layer has a valence band top of a material of the hole transport layer.
  • the difference between the energy level and the work function of the second hole injection material in the second hole injection layer is less than -0.2 eV.
  • the anode direction is increased.
  • the hole injection barrier of the HIL reduces the overall rate of hole injection in the QLED device and effectively controls the number of holes entering the QLED device. On the one hand, it effectively reduces the rate of hole injection into the light-emitting layer, balances the hole-electron injection rate in the light-emitting layer, and improves the carrier recombination efficiency; on the other hand, it can avoid excessive hole injection in HTL and HIL.
  • Charge accumulation is formed at the interface to prevent irreversible damage to the life of the device caused by the charge accumulation at the interface.
  • a hole blocking barrier from HTL to HIL is formed, which prevents holes from diffusing to the HIL layer, improves the utilization rate of holes, and ensures the effective "survival" of holes before being injected into the light-emitting layer.
  • the holes injected in the device are fully and effectively utilized, the luminous efficiency of the device is guaranteed, and the device efficiency and service life are improved at the same time.
  • the quantum dot material of the core-shell structure contained in the quantum dot light-emitting layer of the optoelectronic device has a valence band top energy level difference between the outer shell layer material and the hole transport material greater than 0 eV, that is, ⁇ E EML-HTL >0,
  • the hole injection barrier existing in the light-emitting layer and the barrier between HTL and HIL make the transport layer form a hole carrier trap, effectively "storing" the accumulated holes without diffusing to the outside of the HTL layer.
  • the valence band top energy level difference between the outer shell layer material of the quantum dot material and the hole transport material is greater than or equal to 0.5eV ⁇ 1.7eV, that is, the ⁇ E EML-HTL is 0.5eV ⁇ 1.7eV, forming a better empty space.
  • Hole carrier trap in practical application, the hole carrier hydrazine is used to control the injection balance of holes and electrons in the light-emitting layer of the device more precisely, and improve the carrier recombination efficiency.
  • the difference between the valence band top energy level of the hole transport layer material and the work function of the second hole injection material is -0.9eV ⁇ -0.2eV, and the difference between ⁇ E HTL-HIL is -0.9eV ⁇ - 0.2eV, in this range, the injection and transport of holes have a better balance effect. If it is lower than -0.9eV, the hole injection resistance is too large, which will lead to too little hole injection, which is not conducive to the balanced injection and effective recombination of holes and electrons in the light-emitting layer; if the potential barrier is greater than -0.2eV, the hole injection It is easy to form accumulation at the interface, and the utilization rate is not high.
  • the absolute value of the work function of the second hole injection material is 5.4 eV ⁇ 5.8 eV.
  • the absolute value of the work function of the second hole injection material in the embodiment of the present application is 5.4 eV to 5.8 eV, which is favorable for forming a hole blocking barrier with an energy range of less than -0.2 eV with the hole transport material.
  • the absolute value of the valence band of the conventional hole transport material is about 5.3-5.4 eV
  • the second hole injection material with the absolute value of the work function greater than or equal to 5.4 eV can form a negative energy less than -0.2 eV with the conventional hole transport material level difference, thereby forming a hole blocking barrier, optimizing the hole injection rate, and improving the hole utilization rate.
  • the mobility of the hole transport material is higher than 1 ⁇ 10 -4 cm 2 /Vs
  • the embodiment of the present application adopts a hole transport material with a mobility higher than 1 ⁇ 10 -4 cm 2 /Vs to ensure that The transport and migration effect of holes prevents charge accumulation, eliminates interface charges, and better reduces device driving voltage and improves device life.
  • the hole injection material is selected from a metal oxide material. That is, in some embodiments, when the optoelectronic device includes a first hole injection layer, the first hole injection material in the first hole injection layer is selected from metal oxide materials. In other specific embodiments, when the optoelectronic device includes a second hole injection layer, the second hole injection material in the second hole injection layer is selected from metal oxide materials.
  • the metal oxide material used as the hole injection material has better stability and is not acidic, which not only meets the requirements for hole injection in the above embodiments, but also does not affect adjacent holes.
  • the functional layer has a negative impact. It avoids the degradation of the device life caused by the thermal effect or the electrical effect damage of the organic hole injection material during the working process of the device, and at the same time avoids the damage to the adjacent functional layer caused by the acidity of the organic hole injection material.
  • the metal oxide material includes at least one metal nanomaterial selected from tungsten oxide, molybdenum oxide, vanadium oxide, nickel oxide, and copper oxide. These metal nanomaterials not only have better stability, but also have no acidity. , and in the actual application process, the size of the work function can be adjusted to realize the construction of energy level barriers of different sizes with the hole transport layer, which is beneficial to control hole injection and transport, improve the carrier recombination efficiency, and avoid charge accumulation. impact on device life.
  • the particle size of the metal oxide material is 2 to 10 nm, and the metal oxide material with a small particle size is more conducive to depositing a thin film with a dense film layer and a uniform thickness, which improves the bonding with the adjacent functional layer. It can reduce the interface resistance, which is more conducive to improving the device performance.
  • the hole injection material can also be poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT:PSS), HIL2, HIL1-1, HIL1-2, copper phthalocyanine (CuPc), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinone-dimethane (F4-TCNQ), 2,3,6,7,10,11-hexa Organic hole injection materials such as cyano-1,4,5,8,9,12-hexaazatriphenylene (HATCN).
  • PEDOT:PSS poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid
  • HIL2 HIL1-1, HIL1-2
  • CuPc copper phthalocyanine
  • F4-TCNQ 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinone-dimethane
  • HTCN 2,3,6,7
  • PEDOT:PSS contains the structural formula: The organic molecule of , its work function is -5.1eV; HIL2 contains the structural formula: The organic molecule of , its work function is -5.6eV; HIL1-1 and HIL1-2 both contain the structural formula: The work function of HIL1-1 is -5.4 eV and the work function of HIL1-2 is -5.3 eV.
  • the thickness of the first hole injection layer is 10-150 nm. In other embodiments, the thickness of the second hole injection layer is 10-150 nm.
  • the thickness of the hole injection layer of the present application can be flexibly adjusted according to actual application requirements, and at the same time, the hole injection rate can be better adjusted by adjusting the thickness of the hole injection layer.
  • the hole transport material is selected from at least one of TFB, poly-TPD, P11, P09, P13, P15, P12.
  • the mobility of the hole transport material is higher than 1 ⁇ 10 ⁇ 4 cm 2 /Vs.
  • the hole transport material provided by the above embodiments of the present application can not only build a hole injection barrier with an energy level difference greater than or equal to 0.5 eV with the outer shell layer material of the quantum dot material, but also effectively ensure the migration rate of holes and avoid the slow migration rate. Charge accumulation increases the service life of the device.
  • the embodiments of the present application achieve the purpose of reducing the hole injection rate in the QLED device, regulating the injection and recombination efficiency of carriers, and avoiding HIL and HTL at the same time. Interfacial charge accumulation causes irreversible damage to device lifetime performance.
  • a fourth aspect of the present application provides an optoelectronic device, the hole transport layer of the optoelectronic device comprises at least two hole transport materials, wherein the valence band top energy level of at least one hole transport material The absolute value of is less than or equal to 5.3 eV, and the absolute value of the top energy level of the valence band of at least one hole transport material is greater than 5.3 eV.
  • the hole transport layer of the optoelectronic device provided by the fourth aspect of the present application is a hybrid material, wherein the top energy level of the valence band of at least one hole transport material is less than or equal to 5.3 eV, while the shell energy level of conventional quantum dot light-emitting materials is often relatively Deep (6.0 eV or deeper), therefore, an energy level difference of 0.5 eV or more is formed between the hole transport material of the shallow energy level and the quantum dot shell material.
  • the hole transport layer through the combination of shallow-level materials and deep-level materials, the fine control of the hole injection barrier between the hole transport material and the quantum dot shell layer can be achieved.
  • the hole transport material with deep energy levels modulates the hole mobility in the HTL layer.
  • the hole transport layer further includes a hole transport material whose absolute value of the top energy level of the valence band is greater than 5.3 eV and less than 5.8 eV. In some embodiments, the hole transport layer further includes a hole transport material whose absolute value of the top energy level of the valence band is greater than or equal to 5.8 eV. In other embodiments, the hole transport layer simultaneously includes a hole transport material with an absolute value of the top energy level of the valence band greater than 5.3 eV and less than 5.8 eV and holes with an absolute value of the top energy level of the valence band greater than or equal to 5.8 eV transfer material.
  • the hole injection barrier can be flexibly adjusted according to practical application requirements, device systems and other factors, so that the injection energy level barrier of holes to the light-emitting material is greater than or equal to 0.5eV, reducing the injection efficiency of holes, so as to balance the injection balance of holes and electrons in the light-emitting layer, and the application is flexible and convenient.
  • the electron transport layer of the optoelectronic device is selected to include: an organic electron transport material layer, ZnO nanoparticles, etc. At least one of a metal oxide nanoparticle layer, a sputter deposited metal oxide layer.
  • the hole transport layer when the hole transport layer includes at least one hole transport material with a valence band top energy level of less than or equal to 5.3 eV and a valence band top energy level greater than 5.3 eV and less than 5.8 eV, the hole transport The layer has a relatively moderate top energy level of the valence band and hole mobility, so it can be well matched with conventional metal oxides such as ZnO or organic electron transport materials, which is beneficial to the regulation of the charge balance between holes and electrons.
  • the electron transport layer of the optoelectronic device is selected to include: metal oxide nanoparticles, and the surface groups are selected to connect more Fewer metal oxide nanoparticles.
  • the hole transport layer includes a hole transport material whose valence band top energy level is greater than 5.8 eV, the energy level and mobility are both the same as the valence band top energy level of the aforementioned hole transport material.
  • the hole transport layer materials with a shallow valence band top energy level of less than or equal to 5.3eV have great differences, and continuous regulation in a large window range can be achieved through different mixing ratios, which is suitable for devices from the initial state to continuous operation to QLED device systems with more variable electron injection and transport changes during steady state, such as metal oxide nanoparticles with fewer surface groups attached.
  • the mass percentage of the hole transport material whose absolute value of the top energy level of the valence band is less than or equal to 5.3 eV is 30-90%; According to the content, it can form a hole injection barrier greater than or equal to 0.5eV with the outer shell layer of the luminescent material. In practical applications, the mixing ratio of materials of each energy level can be flexibly adjusted according to the depth of the material energy level.
  • the mobility of at least one hole transport material is higher than 1 ⁇ 10 -3 cm 2 /Vs, and the high mobility of the hole transport material in the embodiments of the present application ensures that holes It can improve the transport and migration performance and avoid the accumulation of holes at the interface, which will affect the device performance.
  • the top energy level of the valence band of the hole transport layer material with high hole mobility is relatively shallow, which also ensures the formation of a suitable energy range with the quantum dot shell material.
  • the mobility of the at least one hole transport material in the hole transport layer is higher than 1 ⁇ 10 ⁇ 2 cm 2 /Vs. In other specific embodiments, in the hole transport layer, the mobility of each hole transport material is higher than 1 ⁇ 10 -3 cm 2 /Vs.
  • the above-mentioned embodiments of the present application optimize the mobility of hole transport materials, ensure the hole transport efficiency, avoid charge accumulation affecting device performance, and ensure the combination of deep and shallow hole transport materials in the hole transport layer.
  • the injection barrier of the hole ensures the formation of an energy level barrier with ⁇ E EML-HTL greater than or equal to 0.5eV, and optimizes the injection balance and recombination efficiency of carriers in the QLED device.
  • a fifth aspect of the present application provides an optoelectronic device, the hole transport layer of the optoelectronic device includes at least two kinds of hole transport materials, and the absolute value of the top energy level of the valence band of the hole transport materials is less than is equal to 5.3eV.
  • the hole transport layer of the optoelectronic device provided by the fifth aspect of the present application is a mixed material, and the top energy level of the valence band of the hole transport material is all less than or equal to 5.3 eV, and the quantum dot light-emitting material with a deeper shell energy level can form a quantum dot light-emitting material greater than or equal to 0.5eV energy level difference.
  • the device ⁇ E EML-HTL ⁇ 0.5 eV. Therefore, after the QLED device enters a stable working state, the charge injection balance and the device efficiency are maintained, and the device life is optimized.
  • the hole mobility of the mixed hole transport layer can also be finely regulated by different mixing ratios by using the different hole mobilities of the hole transport layer materials that are also all of the hole transport layer materials with shallow valence band top energy levels.
  • the mass percentage of each hole transport material is 5-95%.
  • the hole mobility and injection barrier of the hole transport layer can be better controlled.
  • the mobility of at least one hole transport material is higher than 1 ⁇ 10 -3 cm 2 /Vs, and the hole transport layer material with high hole mobility has a top energy level in the valence band. relatively shallow.
  • the mobility of the hole transport material is limited, and the high mobility ensures the transport and mobility of holes, and at the same time ensures the formation of a more suitable injection barrier, so as to avoid the accumulation of holes at the interface and affect the device performance.
  • the mobility of at least one hole transport material in the hole transport layer is higher than 1 ⁇ 10 ⁇ 2 cm 2 /Vs.
  • the mobility of each hole transport material in the hole transport layer is higher than 1 ⁇ 10 ⁇ 3 cm 2 /Vs.
  • the selection of the electron transport layer of the optoelectronic device includes: surface-passivated metal oxide nanoparticles, and the selected surface is sufficient Modification of passivated metal oxide nanoparticles.
  • the top energy level of the valence band of the hole transport material in the hole transport layer is all less than or equal to 5.3 eV, it is necessary to correspond to the material with small changes in electron injection and transport. At this time, it is suitable for the device from the initial state to continuous operation to a stable state. QLED device systems with less variation in electron injection and transport changes during the process, such as metal oxide nanoparticles with adequate surface modification and passivation.
  • the hole transport material is at least one selected from the group consisting of polymers containing aniline groups and copolymers containing fluorene groups and aniline groups, and these hole transport materials have holes It has the advantages of high transmission efficiency, good stability and easy access.
  • hole transport materials with suitable energy level and mobility can be selected according to the actual application requirements, specifically:
  • a hole transport material with an absolute value of valence band top energy level less than or equal to 5.3 eV can be selected: At least one of P09 and P13. Among them, the structural formula of P13 is: The structural formula of P09 is:
  • the transmission material includes: at least one of TFB, poly-TPD, and P11.
  • the structural formula of P11 is:
  • the structural formula of poly-TPD is:
  • the structural formula of TFB is:
  • the hole transport material with an absolute value of valence band top energy level greater than or equal to 5.8 eV includes: At least one of P15 and P12. Among them, the structural formula of P12 is: The structural formula of P15 is:
  • the mobility of the hole transport material is higher than 1 ⁇ 10 -4 cm 2 /Vs, and the high mobility ensures the transport and mobility of holes and avoids the effect of charge accumulation on the device lifetime.
  • the quantum dot material of the core-shell structure further includes an inner core, and an intermediate shell layer located between the inner core and the outer shell layer; wherein, the top energy level of the valence band of the core material is shallower than the valence band of the outer shell layer material Top energy level; the top energy level of the valence band of the intermediate shell material is between the top energy level of the valence band of the core material and the top energy level of the valence band of the outer shell material.
  • the core material determines the luminescence performance
  • the shell material plays the role of protection and facilitates the injection of carriers
  • the intermediate shell layer with the valence band between the core and the shell layer plays an intermediate role.
  • the transition effect is more conducive to carrier injection.
  • the intermediate shell layer can form a stepped energy level transition from the inner core to the outer shell layer, which helps to achieve effective carrier injection, effective confinement and reduction of lattice. interface flickering.
  • the outer shell layer of the quantum dot material includes: an alloy material formed by at least one or at least two of CdS, ZnSe, ZnTe, ZnS, ZnSeS, CdZnS, and PbS.
  • These shell layer materials not only protect and facilitate the injection of carriers into the quantum dot core for light emission, but also form an energy level barrier with ⁇ E EML-HTL greater than or equal to 0.5eV with the HTL layer material.
  • the injection efficiency of holes is improved, so as to balance the injection balance of holes and electrons in the light-emitting layer, improve the luminous efficiency of the device, and avoid the influence of charge accumulation on the life of the device.
  • the inner core of the quantum dot material includes: at least one of CdSe, CdZnSe, CdZnS, CdSeS, CdZnSeS, InP, InGaP, GaN, GaP, ZnSe, ZnTe, ZnTeSe.
  • the luminescent properties of quantum dot materials are related to the core materials. These materials ensure that QLED devices can emit light in the visible light range of 400-700 nm, which not only meets the range required for the application of optoelectronic display devices, but also the beneficial effects achieved by the energy level relationship of these materials can be achieved. better reflect.
  • the intermediate shell material is selected from at least one of CdZnSe, ZnSe, CdZnS, CdZnSeS, CdS, CdSeS.
  • the composition of the intermediate shell layer preferably forms a continuous and natural transition from the inner core to the outer layer, which helps to achieve the least crystallinity among the inner core, the intermediate shell and the outer shell. Lattice mismatch and minimum lattice defects, so as to achieve the optimal luminescence performance of the core-shell quantum dot material itself.
  • the emission peak wavelength range of the quantum dot material is 400-700 nm. On the one hand, this wavelength range is required for the application of optoelectronic display devices; The beneficial effect can be better reflected.
  • the thickness of the outer shell layer of the quantum dot material is 0.2-6.0 nm, which covers the thickness of the conventional outer shell and can be widely used in QLED devices of different systems. If the thickness of the outer shell layer is too large, the rate at which carriers are injected into the light-emitting quantum dots through the tunneling effect will decrease; and if the thickness of the outer shell layer is too small, the outer shell material cannot sufficiently protect and passivate the core material. , which affects the luminescence and stability properties of quantum dot materials.
  • the optoelectronic device further includes an electron transport layer
  • the electron transport material in the electron transport layer is selected from at least one of metal oxo compound transport materials and organic transport materials.
  • metal oxide materials generally have high electron mobility, and can be prepared into thin films in QLED devices by solution method or vacuum sputtering method.
  • Organic electron transport layer materials can achieve energy level regulation in a wide range, and can be prepared into thin films in QLED devices by vacuum evaporation or solution methods; solution methods include inkjet printing, spin coating, jet printing , slot coating or screen printing, etc. More suitable electron transport materials can be flexibly selected according to actual application requirements.
  • the metal oxide transport material is selected from at least one of zinc oxide, titanium oxide, zinc sulfide, cadmium sulfide. These metal oxo compound transport materials used in the above embodiments of the present application all have high electron transfer efficiency. In some embodiments, in order to improve electron transfer efficiency, the metal oxo compound transport material is selected from at least one of zinc oxide, titanium oxide, zinc sulfide, and cadmium sulfide doped with metal elements, wherein the metal elements include aluminum, At least one of magnesium, lithium, lanthanum, yttrium, manganese, gallium, iron, chromium, and cobalt, these metal elements can improve the electron transfer efficiency of the material.
  • the particle size of the metal oxo compound transport material is less than or equal to 10 nm.
  • the metal oxy compound transport material with small particle size is more conducive to the deposition of electron transport layer films with dense film layers and uniform thickness. The tightness of its bonding with the adjacent functional layers reduces the interface resistance and is more conducive to improving the performance of the device.
  • the metal oxide compound transport material with small particle size has a wider band gap, which reduces the quenching of the exciton emission of the quantum dot material and improves the device efficiency.
  • the electron mobility of the metal oxo compound transport material is 10 -2 to 10 -3 cm 2 /Vs, and the electron transport material with high mobility can reduce the accumulation of charges in the interface layer, improve electron injection, compound efficiency.
  • the electron mobility of the organic transport material is not less than 10 ⁇ 4 cm 2 /Vs.
  • the organic transport material is selected from at least one of NaF, LiF, CsF, 8-hydroxyquinoline-lithium, Cs 2 CO 3 , and Alq 3 . These organic transport materials can realize energy level regulation in a wide range, which is more conducive to regulating the energy levels of each functional layer of the device and improving the stability and photoelectric conversion efficiency of the device.
  • the electron transport layer is a laminated composite structure, which includes at least two sub-electron transport layers.
  • the electron transport layer can be regulated more flexibly to better optimize device performance.
  • the material of at least one sub-electron transport layer is a metal oxo compound transport material.
  • all sub-electron transport layers are metal oxides, and the metal oxide materials of different sub-electron transport layers may be the same or different. That is, in the multilayer electron transport layer in which all the sub-electron transport layers are metal oxides, there may be a sub-electron transport layer comprising at least one layer of metal oxide nanoparticles and at least one layer of non-nanoparticle type metal oxides. Sub electron transport layer.
  • the sub-electron transport layers can be doped and intrinsic metal oxides (eg, Mg-doped ZnO + intrinsic ZnO), respectively. It can also be that the sub-electron transport layers are all of the same metal oxide nanoparticles. When the sub-electron transport layers are all of the same metal oxide nanoparticle, the electron mobilities of different sub-electron transport layers may be the same or different.
  • the material of at least one sub-electron transport layer is an organic transport material. In some embodiments, in the electron transport layer, the material of at least one sub-electron transport layer is a metal oxo compound transport material, the material of at least one sub-electron transport layer is an organic transport material, and the metal oxide of different sub-electron transport layers
  • the metal oxide materials can be the same or different; the metal oxide materials are selected as nanoparticles of the corresponding metal oxide.
  • the electron transport layer has both high electron mobility and flexibility of energy level matching through the co-coordination of the metal oxo compound transport material and the organic transport material in the electron transport layer.
  • the electron transport layer comprising multiple sub-electron transport layers may be a combination of ZnO nanoparticles + NaF, a combination of Mg-doped ZnO nanoparticles + NaF, and other stacked composite structures.
  • the core material determines the luminescence properties of the quantum dot material
  • the shell material plays a protective role and is conducive to carrier injection.
  • the thickness of the shell layer and the top energy level of the valence band of the hole transport material can be adjusted so that the difference in the top energy level of the valence band between the shell layer material of the quantum dot material and the hole transport material is greater than or equal to 0.5 eV, that is, to construct the expected injection barrier, E EML-HTL ⁇ 0.5 eV, optimize the balance of electron and hole injection efficiency in the light-emitting layer, and improve the device efficiency and service life.
  • the device is not limited by the device structure, and may be a device with a positive structure or a device with an inversion structure.
  • the positive structure optoelectronic device includes a stacked structure of oppositely disposed anode and cathode, a light-emitting layer disposed between the anode and the cathode, and the anode disposed on the substrate.
  • a hole functional layer such as a hole injection layer and a hole transport layer can also be provided between the anode and the light emitting layer; and an electron functional layer such as an electron transport layer and an electron injection layer can also be provided between the cathode and the light emitting layer. layer, as shown in Figure 2.
  • the optoelectronic device includes a substrate, an anode disposed on the surface of the substrate, a hole transport layer disposed on the surface of the anode, a light emitting layer disposed on the surface of the hole transport layer, An electron transport layer on the surface of the layer and a cathode disposed on the surface of the electron transport layer.
  • the inversion structure optoelectronic device comprises a stacked structure of oppositely disposed anode and cathode, a light-emitting layer disposed between the anode and the cathode, and the cathode disposed on the substrate.
  • a hole functional layer such as a hole injection layer and a hole transport layer can also be set between the anode and the light-emitting layer; and an electron functional layer such as an electron transport layer and an electron injection layer can also be set between the cathode and the light-emitting layer, as shown in Figure 3 shown.
  • the optoelectronic device includes a substrate, a cathode disposed on the surface of the substrate, an electron transport layer disposed on the surface of the cathode, a light emitting layer disposed on the surface of the electron transport layer,
  • the hole transport layer is an anode disposed on the surface of the hole transport layer.
  • the choice of the substrate is not limited, and a rigid substrate or a flexible substrate may be used.
  • the rigid substrate includes, but is not limited to, one or more of glass and metal foil.
  • the flexible substrate includes, but is not limited to, polyethylene terephthalate (PET), polyethylene terephthalate (PEN), polyetheretherketone (PEEK), polystyrene (PS), polyethersulfone (PES), polycarbonate (PC), polyarylate (PAT), polyarylate (PAR), polyimide (PI), polyvinyl chloride (PV), poly One or more of ethylene (PE), polyvinylpyrrolidone (PVP), and textile fibers.
  • PET polyethylene terephthalate
  • PEN polyethylene terephthalate
  • PEEK polyetheretherketone
  • PS polystyrene
  • PS polyethersulfone
  • PC polycarbonate
  • PAT polyarylate
  • PAR polyarylate
  • PI polyimide
  • PV polyviny
  • the choice of anode material is not limited and can be selected from doped metal oxides, including but not limited to indium doped tin oxide (ITO), fluorine doped tin oxide (FTO), antimony doped tin oxide (ATO), Aluminum-Doped Zinc Oxide (AZO), Gallium-Doped Zinc Oxide (GZO), Indium-Doped Zinc Oxide (IZO), Magnesium-Doped Zinc Oxide (MZO), Aluminum-Doped Magnesium Oxide (AMO) one or more.
  • doped metal oxides including but not limited to indium doped tin oxide (ITO), fluorine doped tin oxide (FTO), antimony doped tin oxide (ATO), Aluminum-Doped Zinc Oxide (AZO), Gallium-Doped Zinc Oxide (GZO), Indium-Doped Zinc Oxide (IZO), Magnesium-Doped Zinc Oxide (MZO), Aluminum-Doped Magnesium Oxide (AMO)
  • the cathode material may be one or more of various conductive carbon materials, conductive metal oxide materials, and metallic materials.
  • conductive carbon materials include, but are not limited to, doped or undoped carbon nanotubes, doped or undoped graphene, doped or undoped graphene oxide, C60, graphite, carbon fiber, many Empty carbon, or a mixture thereof.
  • the conductive metal oxide material includes, but is not limited to, ITO, FTO, ATO, AZO, or mixtures thereof.
  • the metal materials include, but are not limited to, Al, Ag, Cu, Mo, Au, or their alloys; among the metal materials, their forms include but are not limited to dense films, nanowires, nanospheres, nanometers Rods, nano cones, nano hollow spheres, or their mixtures; the cathode is Ag, Al.
  • the quantum dot light-emitting layer has a thickness of 8-100 nm.
  • the hole transport layer has a thickness of 10-150 nm.
  • the electron transport layer has a thickness of 10-200 nm.
  • the electronic functional layer, the light-emitting layer, and the hole functional layer in the device can be designed with appropriate functional layers according to the characteristics of the device in the above embodiments.
  • a hole injection layer is grown on the surface of the anode
  • an electron transport layer is deposited on the quantum dot light-emitting layer, and a cathode is evaporated on the electron transport layer to obtain an optoelectronic device.
  • step S10 the ITO substrate needs to undergo a pretreatment process, and the steps include: cleaning the ITO conductive glass with a detergent to preliminarily remove the stains existing on the surface, and then sequentially soaking in deionized water, acetone, anhydrous ethanol, and deionized water. Ultrasonic cleaning was carried out for 20 min to remove impurities on the surface, and finally dried with high-purity nitrogen to obtain the ITO positive electrode.
  • the step of growing the hole injection layer includes: preparing a metal oxide and other materials into a thin film in the QLED device by a solution method, a vacuum sputtering method, and a vacuum evaporation method; wherein, the solution method method Including inkjet printing, spin coating, spray printing (spray printing), slot-die printing (slot-die printing) or screen printing (screen printing) and the like.
  • the step of growing the hole transport layer includes: placing the ITO substrate on a spin coater, and using the prepared solution of the hole transport material to spin to form a film; adjusting the concentration of the solution and the spin coating speed and spin coating time to control the film thickness, followed by thermal annealing at an appropriate temperature.
  • the step of depositing the quantum dot light-emitting layer on the hole transport layer includes: placing the substrate on which the hole transport layer has been spin-coated on a spin coater, and spinning a solution of a prepared light-emitting substance with a certain concentration. Coating into a film, controlling the thickness of the light-emitting layer by adjusting the concentration of the solution, the spin coating speed and the spin coating time, about 20-60 nm, and drying at an appropriate temperature.
  • the step of depositing the electron transport layer on the quantum dot light-emitting layer includes: placing the substrate on which the quantum dot light-emitting layer has been spin-coated on a spin coater, and preparing a certain concentration of electron transport composite material
  • the solution is spin-coated to form a film by drip coating, spin coating, soaking, coating, printing, evaporation and other processes, and is controlled by adjusting the concentration of the solution, the spin coating speed (for example, the rotation speed is between 3000 and 5000 rpm) and the spin coating time.
  • the thickness of the electron transport layer is about 20 to 60 nm, and then annealed under the conditions of 150 ° C to 200 ° C to form a film, and the solvent is fully removed.
  • the cathode preparation step includes: placing the substrate on which each functional layer has been deposited into an evaporation chamber and thermally evaporated a layer of 60-100 nm metal silver or aluminum as a cathode through a mask plate.
  • the method for preparing an optoelectronic device further includes encapsulating the laminated optoelectronic device; the curing resin used in the encapsulation is acrylic resin, acrylate resin or epoxy resin; resin curing adopts UV irradiation, Heat or a combination of both.
  • the encapsulation process can be done by conventional machine encapsulation or manual encapsulation. In the packaging process environment, the oxygen content and water content are both lower than 0.1ppm to ensure the stability of the device.
  • the method for preparing an optoelectronic device further includes, after encapsulating the optoelectronic device, introducing one or more processes including ultraviolet irradiation, heating, positive and negative pressure, applied electric field, and applied magnetic field; applying a process
  • the atmosphere can be air or an inert atmosphere.
  • the devices in the embodiments of the present application all adopt the ITO/HIL/HTL/QD/ETL/AL structure, and a certain heating treatment is performed after packaging.
  • the advantages of the technical solutions of the present application are explained in detail by comparing the collocation of different functional layers in the device.
  • the life test adopts the constant current method, under the constant current of 50mA/ cm2 , the silicon photosystem is used to test the brightness change of the device, and the time when the brightness of the device starts from the highest point and decays to 95% of the highest brightness is recorded LT95, Then extrapolate the 1000nit LT95S life of the device through the empirical formula.
  • This method is convenient for comparing the lifetime of devices with different brightness levels, and has a wide range of applications in practical optoelectronic devices.
  • the energy level test method of each material in the examples of the present application after spin-coating each functional layer material to form a film, the energy level test is carried out by UPS (ultraviolet photoelectron spectroscopy) method.
  • UPS ultraviolet photoelectron spectroscopy
  • Valence band top VB(HOMO): E HOMO E F-HOMO + ⁇ , where E F-HOMO is the difference between the material HOMO(VB) and the Fermi level, corresponding to the first occurrence of the low binding energy end in the binding energy spectrum the starting edge of a peak;
  • E LOMO E HOMO -E HOMO-LOMO
  • E HOMO-LOMO is the band gap of the material, obtained from UV-Vis (ultraviolet absorption spectrum).
  • this application sets up Examples 1 to 11, and compares the combinations of different HTLs and QDs to illustrate the empty space.
  • the effect of hole injection barrier on performance such as device lifetime.
  • the two kinds of quantum dots used in Examples 1 to 11 of the present application are: blue QD1 whose outer shell is CdZnS (the inner core is CdZnSe, the middle shell is ZnSe, the outer shell thickness is 1.5 nm, and the top energy level of the valence band is 6.2 eV),
  • the outer shell is a blue QD2 of ZnS (the inner core is CdZnSe, the intermediate shell is ZnSe, the ZnS shell thickness is 0.3 nm, and the valence band top energy level is 6.5 eV).
  • the blue QD3 with ZnSeS shell (the inner core is CdZnSe, the middle shell is ZnSe), the hole transport materials are P9 (E HOMO : 5.1 eV), P15 (E HOMO : 5.8 eV), and the hole injection layer is PEDOT:PSS (E HOMO : 5.1eV), the electron transport layer is made of ZnO nanomaterials with amine/carboxyl ligands with a chain length of 3 to 8 carbon atoms bound on the surface, using amine/carboxyl ligand compounds (Ligand) and zinc oxide
  • the precursor (Precursor) is prepared by the sol-gel method, as shown in Table 1 below:
  • the ⁇ E EML-HTL barrier difference increases from 0.4eV to 0.7eV, and the device lifetime is significantly improved
  • the 1000nit LT95S life is increased from 0.72 to 6.29.
  • the device injection balance is optimized, and the device lifetime can be enhanced. It shows that reducing the hole injection efficiency by increasing the hole injection barrier can better balance the injection balance of holes and electrons in the light-emitting layer, and improve the luminous efficiency and luminous life of the device. In addition, it can be seen from Examples 7-11 that when the carbon chains of ZnO surface-bound ligands are 3-8, the device performance is better promoted.
  • this application sets up Examples 12 to 15, through the comparison of different HTL and HTL, to illustrate the effect of the ⁇ E HTL-HIL hole injection barrier on the device life. and other performance effects.
  • blue quantum dots with ZnS outer shells (the inner core is CdZnSe, the middle shell is ZnSe, the outer shell thickness is 0.3 nm, and the top energy level of the valence band is 6.5 eV) are used, and in Examples 14 to 15
  • the red quantum dots with the outer shell of ZnS (the core is CdZnSe, the middle shell is ZnSe, the shell thickness is 0.3 nm, and the top energy level of the valence band is 6.5 eV) are used, and the hole transport materials are P9 (E HOMO : 5.5 eV), P11 (E HOMO : 5.5eV), P13 (E HOMO : 4.9eV), the hole injection layer adopts PEDOT:PSS (E HOMO : 5.1eV) and HIL2 (work function: 5.6eV), and the electron transport layer adopts surface-bonded
  • the ZnO nanomaterial of propylamine ligand is obtained by sol
  • blue quantum dots whose outer shells are ZnS are ZnS (the inner core is CdZnSe, the middle shell is ZnSe, the outer shell thickness is 0.3 nm, and the top energy level of the valence band is 6.5 eV) are used, and in Examples 19 to 23
  • the red quantum dots with the outer shell of ZnS (the core is CdZnSe, the middle shell is ZnSe, the shell thickness is 0.3 nm, and the top energy level of the valence band is 6.5 eV) are used, and the hole transport materials are P9 (E HOMO : 5.5 eV), P13 (E HOMO : 4.9 eV), TFB (E HOMO : 5.4 eV), the hole injection layer adopts PEDOT: PSS (E HOMO : 5.1 eV), HIL1-1 (work function: 5.4 eV) and HIL1-2 (work function: 5.4 eV)
  • the electron transport layer is made of Zn
  • red quantum dots whose outer shells are ZnS are used in Examples 24 to 26.
  • red quantum dots whose outer shells are ZnS are used in Examples 27-28.
  • red quantum dots whose outer shells are ZnS are used in Examples 27-28.
  • the electron transport layer is made of ZnO nanomaterials with propylamine ligands bound on the surface. As shown in Table 4:
  • the damage of the hole injection material of MoO 3 is effectively suppressed, so that the voltage rise of the device in the working process is compared with that of the organic material.
  • the hole injection layer material device has a significant reduction, and the measured time of the device life has also been effectively improved.

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Abstract

本申请公开一种光电器件，包括依次叠层设置的阳极、空穴传输层、量子点发光层、电子传输层和阴极，量子点发光层中包括核壳结构的量子点材料，量子点材料的外壳层材料与空穴传输材料的价带顶能级差大于等于0.5eV；电子传输层中包含有氧化锌纳米材料，氧化锌纳米材料的表面结合有链长为3～8个碳原子的胺基/羧基配体。本申请提供的光电器件，构建≥0.5eV的空穴注入势垒降低空穴注入效率，同时电子传输层采用表面结合有链长为3～8个碳原子的胺基/羧基配体的氧化锌材料，提高电子迁移注入效率，使发光器件中空穴与电子的注入速率平衡，提高电子与空穴复合效率，避免因载流子注入不平衡导致的电荷积累。

Description

光电器件
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202011639205.6、发明名称为“光电器件”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，具体涉及一种光电器件。
背景技术
这里的陈述仅提供与本申请有关的背景信息，而不必然构成现有技术。量子点发光显示技术(QLED)是近年来迅速兴起的一种新型显示技术，QLED与有机发光显示(OLED)类似，均为主动发光技术，因此同样具有发光效率高、响应速度快、对比度高、可视角度宽等优点。由于QLED显示技术中量子点自身所具有的优良材料特性，使得QLED在众多方面比OLED更具性能优势，如：量子点的发光连续可调且发光宽度极窄，可实现更广色域更高纯度显示；量子点的无机材料特性使得QLED具有更好的器件稳定性；QLED器件的驱动电压比OLED更低，能实现更高亮度并降低能耗；同时QLED显示技术与印刷显示的生产工艺和技术相匹配，能够实现大尺寸、低成本、可卷曲的高效量产制备。因此，QLED被认为是未来轻薄，便携，柔性，透明，高性能的下一代显示屏幕的首选技术之一。
由于QLED与OLED显示技术在发光原理上的相似性，因此，目前在QLED显示技术的开发过程中，QLED的器件结构更多地都是借鉴OLED显示技术，除了发光层材料由有机发光材料替换为量子点材料外，其他功能层材料诸如电荷注入层或电荷传输层等材料往往是利用OLED中已有的材料。同时对于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也均是遵循OLED中的已有理论体系。将OLED器件研究中所得到经典器件物理结论应用到QLED器件体系中，确实对于QLED器件性能起到了显著的提升效果，尤其是QLED器件效率。
但是，目前OLED中所形成的经典思路和策略均无法实现对QLED器件寿命的有效提升，而且通过OLED器件经典思路和策略虽然能提高QLED器件效率，但研究发现这些高效QLED器件的器件寿命却显著差于具有更低效率的相似器件。因此，现有的基于OLED器件理论体系所设计的QLED器件结构并不能同时提升QLED器件的光电效率和寿命性能。对应于QLED器件体系所具有的独特的器件机制，需要开发新的更具有针对性的新QLED器件结构。
技术问题
本申请实施例的目的之一在于：提供一种光电器件，旨在解决相关技术难以同时提高QLED器件的光电效率和寿命性能的问题。
技术解决方案
为解决上述技术问题，本申请实施例采用的技术方案是：
提供了一种电器件，包括：阳极、在所述阳极上的空穴传输层、在所述空穴传输层上的量子点发光层，在所述量子点发光层上的电子传输层，和在所述电子传输层上的阴极；其中，所述量子点发光层中包括核壳结构的量子点材料，所述量子点材料的外壳层材料与 所述空穴传输层中空穴传输材料的价带顶能级差大于等于0.5eV；所述电子传输层中包含有氧化锌纳米材料，所述氧化锌纳米材料的表面结合有链长为3～8个碳原子的胺基/羧基配体。
本申请实施例提供的光电器件的有益效果在于：一方面，在量子点材料的外壳层材料与空穴传输材料之间构建了大于等于0.5eV的价带顶能级差，即E EML-HTL≥0.5eV。通过提高空穴注入势垒来降低空穴的注入效率，从而平衡发光层中空穴与电子的注入平衡。另一方面，电子传输层中表面结合有链长为3～8个碳原子的胺基/羧基配体的氧化锌纳米材料，链长为3～8个碳原子的胺基/羧基配体置换氧化锌胶体表面的羟基配体，有效降低氧化锌纳米材料表面带负电的羟基基团的含量，减小氧化锌纳米材料的电负性，从而降低带负电的羟基基团对电子传输的抑制和阻碍作用，提高电子迁移注入效率。另外，胺基/羧基配体的链长为3～8个碳原子，链长较短，空间位阻效应小，不会增加电子传输层薄膜中氧化锌纳米颗粒之间的距离以及纳米颗粒间的电子迁移效率。使发光器件中空穴与电子的注入速率平衡，提高电子与空穴复合效率，避免因载流子注入不平衡导致的电荷积累，提高发光器件发光效率和使用寿命。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例或示范性技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其它的附图。
图1是本申请实施例第一方面提供的光电器件的结构示意图；
图2是本申请实施例提供的量子点发光二极管的正型结构示意图；
图3是本申请实施例提供的量子点发光二极管的反型结构示意图。
本发明的实施方式
为了使本申请的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本申请进行详细说明。应当理解，此处所描述的具体实施例仅用以解释本申请，并不用于限定本申请。
本申请中，术语“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B的情况。其中A，B可以是单数或者复数。
本申请中，“至少一个”是指一个或者多个，“多个”是指两个或两个以上。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，“a,b,或c中的至少一项(个)”，或，“a,b,和c中的至少一项(个)”，均可以表示：a,b,c,a-b(即a和b),a-c,b-c,或a-b-c，其中a,b,c分别可以是单个，也可以是多个。
应理解，在本申请的各种实施例中，上述各过程的序号的大小并不意味着执行顺序的先后，部分或全部步骤可以并行执行或先后执行，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本申请实施例的实施过程构成任何限定。在本申请实施例中使用的术语是仅仅出于描述特定实施例的目的，而非旨在限制本申请。在本申请实施例和所附权利要求书中所使用的单数形式的“一种”和“该”也旨在包括多数形式，除非上下文清楚地表示其 他含义。
在本申请实施例中，ΔE HTL-HIL＝E HOMO,HTL-E HIL，ΔE EML-HTL＝E HOMO,EML-E HTL，所有能级/功函值均取绝对值，能级绝对值大表示能级深，能级绝对值小表示能级浅。
在本申请实施例中，氧化锌薄膜表面羟基量通过X射线光电子能谱(XPS)测得，具体地：对氧化锌薄膜进行检测，结果中的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之间)，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之间)。各个子峰之间的面积比就代表了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＝氧化锌薄膜表面上羟基配体的摩尔浓度/氧化锌晶体中氧原子摩尔浓度。
本申请的关键在于同时提高QLED器件的寿命和光电效率。目前，器件寿命的测试与器件效率的表征存在显著的差异：器件效率测试的时间通常较短，因此表征的是QLED器件工作起始时瞬间状态；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。
目前，基于传统OLED器件已有的理论体系，认为电子向发光层注入的速率通常比空穴要快。因此，为平衡以及提高QLED器件发光层中空穴和电子的复合效率，通常会在器件中设置空穴注入层、尽量减小相邻两层功能层之间注入势垒等方式来增强空穴的注入效率，从而提高载流子注入效率并减少界面电荷积累。但是该方法仅能在一定程度上提高QLED器件起始瞬间的光电效率，却无法同时提高器件寿命，甚至会降低器件寿命。本申请通过对于QLED器件机理研究的逐步开展和深入，发现在QLED器件体系中由于量子点材料以及其他具有特殊材料表面的纳米材料的使用，使得QLED具有一些不同于OLED器件体系的特殊机制，这些机制与QLED器件的性能尤其是器件寿命具有密切的关系。
具体地，本申请通过研究发现：QLED器件在初始工作状态时，发光层中电子注入速率比空穴快，导致量子点材料带负电，且这种负电状态会因量子点材料的结构特性和表面配体的束缚作用、库仑阻塞效应等因素得以保持。然而，量子点材料的负电状态使得QLED器件在持续工作过程中，电子的注入变得越来越困难，从而导致发光层中电子与空穴实际注入不平衡。QLED器件持续点亮工作至稳定状态的过程中，量子点材料带负电的状态也趋于稳定，即被量子点新捕获束缚的电子与发生辐射跃迁所消耗的电子达到动态平衡。此时电子向发光层的注入速率相比起始状态时要低很多，达到发光层中电荷注入平衡所需的空穴注入速率实际也相对较低。若仍然基于传统OLED器件的理论体系提高空穴的注入效率，采用深能级的空穴传输层只能在QLED器件工作起始阶段形成电荷注入的瞬间平衡，达到起始瞬间的高器件效率。但是，随着QLED器件进入稳定的工作状态，过量的空穴注入反而会加重器件发光层中电子与空穴的不平衡状态，QLED器件效率无法保持，随之降低。且这种电荷的不平衡状态会随着器件持续工作而不断加剧，导致QLED器件寿命也会相应地迅速衰减。
因此，为了实现在器件发光层中载流子的注入平衡，获得更高效率和更长使用寿命的器件，对器件两侧空穴和电子的载流子注入进行精细调控的关键在于：一方面，调控空穴 注入至较低的速率，同时提高电子的注入效率，使QLED器件稳定工作状态中空穴的注入速率与电子的注入速率平衡，提高QLED器件复合效率。另一方面，由于QLED器件在实际稳定工作状态中所需的空穴注入速率比传统预期的低，容易出现载流子积累，对器件造成不可逆转的破坏。因此，要尽量避免载流子积累对器件寿命的影响，提高器件使用寿命。
如附图1所示，本申请实施例第一方面提供一种光电器件，包括：阳极、在阳极上的空穴传输层、在空穴传输层上的量子点发光层，在量子点发光层上的电子传输层，和在电子传输层上的阴极；其中，量子点发光层中包括核壳结构的量子点材料，量子点材料的外壳层材料与空穴传输层中空穴传输材料的价带顶能级差大于等于0.5eV；电子传输层中包含有氧化锌纳米材料，氧化锌纳米材料的表面结合有链长为3～8个碳原子的胺基/羧基配体。
本申请第一方面提供的光电器件，一方面，在量子点材料的外壳层材料与空穴传输材料之间构建了大于等于0.5eV的价带顶能级差，即E EML-HTL≥0.5eV。通过提高空穴注入势垒来降低空穴的注入效率，从而平衡发光层中空穴与电子的注入平衡。另一方面，电子传输层中表面结合有链长为3～8个碳原子的胺基/羧基配体的氧化锌纳米材料，链长为3～8个碳原子的胺基/羧基配体置换氧化锌胶体表面的羟基配体，有效降低氧化锌纳米材料表面带负电的羟基基团的含量，减小氧化锌纳米材料的电负性，从而降低带负电的羟基基团对电子传输的抑制和阻碍作用，提高电子迁移注入效率。另外，胺基/羧基配体的链长为3～8个碳原子，链长较短，空间位阻效应小，不会增加电子传输层薄膜中氧化锌纳米颗粒之间的距离以及纳米颗粒间的电子迁移效率。
本申请基于目前空穴传输材料的能级特性，以及量子点材料的外壳材料的能级特性，本申请通过研究发现至少需要ΔE EML-HTL≥0.5eV的能级势垒，才能实现空穴注入效率的显著减小，使发光层中电子与空穴注入效率平衡。另外，本申请ΔE EML-HTL≥0.5eV的空穴注入势垒并不会导致空穴无法注入，因为量子点在通电工作状态下外壳层的能级会发生能带弯曲，载流子可以通过隧穿效应实现注入；因而这种能级势垒的增加虽然会造成载流子注入速率的降低，但并不会完全阻碍载流子的最终注入。
本申请实施例核壳结构的量子点材料中内核材料决定发光性能，外壳材料起到保护和利于载流子注入作用，电子、空穴经过外壳层注入到内核进行发光。一般内核的带隙比外壳窄，所以空穴传输材料与量子点内核价带能级差要小于空穴传输材料与量子点外壳价带能级差。因此，ΔE EML-HTL大于等于0.5eV能够同时确保空穴载流子有效的注入量子点材料的内核。
在一些实施例中，量子点材料的外壳层材料与空穴传输层中空穴传输材料的价带顶能级差为0.5～1.7eV，即ΔE EML-HTL为0.5eV～1.7eV，在量子点材料的外壳层材料与空穴传输材料之间构建的该范围的能级势垒，可适用于由不同空穴传输材料和量子点材料构筑的器件体系，优化不同器件体系中电子与空穴的注入平衡。在实际应用中可根据具体的材料性能，设置不同顶价带能级差ΔE EML-HTL的情形，精细调控发光层两侧空穴和电子的载流子注入速率，使空穴和电子注入平衡。
在一些具体实施例中，量子点材料的外壳层材料与空穴传输材料的价带顶能级差为0.5eV～0.7eV，此时适用空穴传输材料为TFB、P12、P15，量子点外壳材料为ZnSe、CdS，如：TFB-ZnSe、P12/P15-CdS等器件体系。
在一些具体实施例中，量子点材料的外壳层材料与空穴传输材料的价带顶能级差为0.7eV～1.0eV，此时适用空穴传输材料为TFB、P09，量子点外壳材料为ZnSe、CdS，如：P09-ZnSe、TFB-CdS等器件体系。
在一些具体实施例中，量子点材料的外壳层材料与空穴传输材料的价带顶能级差为1.0eV～1.4eV，此时适用空穴传输材料为FB、P09、P13、P14，量子点外壳材料为CdS、ZnSe、ZnS，如：TFB-ZnS、P09-CdS、P13/P14-ZnSe等器件体系。
在一些具体实施例中，量子点材料的外壳层材料与空穴传输材料的价带顶能级差大于1.4eV～1.7eV，此时适用P09-ZnS、P13/P14-ZnS的器件体系。
本申请实施例电子传输层中选择表面结合有链长为3～8个碳原子的胺基/羧基配体的氧化锌纳米材料，选择表面结合有链长为4～6个碳原子的胺基/羧基配体的氧化锌纳米材料。若胺基/羧基配体的链长过短，则胺基/羧基配体的酸碱性将会明显增加，在制备过程中胺基/羧基配体会与氧化锌纳米颗粒发生酸碱反应，影响最终成膜的氧化锌薄膜品质；而若胺基/羧基配体的链长过长时，在空间位阻效应的作用下，会增加溶液中以及成膜后氧化锌纳米颗粒之间的距离，进而降低成膜后氧化锌电子传输层的电子迁移率，与原本设计的目的相反，达不到提高电子迁移效率的目的。
在一些实施例中，本申请实施例表面结合有链长为3～8个碳原子的胺基/羧基配体的氧化锌纳米材料，可采用溶胶凝胶法制备，在合成氧化锌胶体溶液的过程中，向氧化锌前驱物溶液中添加合适浓度的链长为3-8个碳的胺基/羧基配体化合物溶液，通过搅拌使配体交换反应充分进行后，进行正常清洗，便可制得表面结合有目标链长的胺基/羧基配体的氧化锌纳米材料。在合成过程中，根据配体链长的大小，通过控制胺基/羧基配体与前驱体的摩尔比，可灵活调控氧化锌纳米材料表面的胺基/羧基配体交换量，从而调控氧化锌纳米颗粒表面带负电的羟基基团量。
在一些实施例中，按胺基/羧基配体化合物与氧化锌前驱体的摩尔比为(1～10)：1，通过溶胶凝胶法制备氧化锌纳米材料。本申请实施例按胺基/羧基配体化合物与氧化锌前驱体的摩尔比为(1～10)：1制备氧化锌纳米材料，将氧化锌纳米颗粒表面羟基量控制在较低的水平，降低带负电的羟基基团对电子传输的抑制和阻碍作用，提高电子迁移注入效率。
本申请在制备氧化锌纳米颗粒时，可根据目标配体碳链的长短，空间位阻大小，与羟基的配体交换效果等因素，综合考虑选择合适的胺基/羧基配体化合物与氧化锌前驱体的配比。在一些具体实施例中，当胺基/羧基配体化合物的链长为3～4个碳原子时，按胺基/羧基配体化合物与氧化锌前驱体的摩尔比为(4～10)：1，制备氧化锌纳米材料。在另一些具体实施例中，当胺基/羧基配体化合物的链长为5～7个碳原子时，按胺基/羧基配体化合物与氧化锌前驱体的摩尔比为(1～5)：1，制备氧化锌纳米材料。
在一些实施例中，胺基/羧基配体化合物选自丙酸、丙胺、丁酸、丁胺、己酸、己胺、戊胺、辛胺中的至少一种。本申请上述实施例采用的胺基/羧基配体化合物链长为3-8个碳原子，与氧化锌纳米颗粒表面的羟基配体交换效果好。
在一些实施例中，氧化锌前驱体选自醋酸锌、硝酸锌、硫酸锌、氯化锌中至少一种。在一些实施例中，在室温下，将醋酸锌、硝酸锌、硫酸锌、氯化锌中至少一种氧化锌前驱体，溶解在水、甲醇、乙醇、丙醇、丁醇、乙二醇、乙二醇单甲醚、二甲基亚砜DMSO等 溶剂中，温度调整至0～70℃后，添加氢氧化钾、氢氧化钠、氢氧化锂、四甲基氢氧化铵TMAH、氨水、乙醇胺、乙二胺等碱液，随后在反应温度保持为0～70℃的情况下将混合溶液持续搅拌/反应30min～4h，向反应结束后的混合溶液中加入沉淀剂进行沉淀。将混合溶液离心，清洗沉淀物，最终所得沉淀溶于溶剂中，即得到氧化锌胶体溶液。而本申请实施例添加链长为3-8个碳的胺基/羧基配体化合物溶液的时间节点，可以是氧化锌胶体溶液合成初期，即和碱液同时添加到氧化锌前驱物溶液中；也可以是在氧化锌胶体溶液合成中期，即向已经添加了碱溶液的氧化锌前驱物溶液中添加；也可以是在氧化锌胶体溶液合成结束后清洗之前的溶液中添加；也可以是在清洗之后得到的最终氧化锌胶体溶液中添加。无论是在哪个阶段添加配体溶液，添加后都需进行10min-2h的搅拌，以使反应充分进行。更优的，搅拌时间为30min-1h。
在一些实施例中，电子传输层为叠层复合结构，除包含有表面结合有链长为3～8个碳原子的胺基/羧基配体的氧化锌纳米材料外，还包括有机传输材料的电子传输层。有机传输材料可以在较宽的范围内实现能级的调控，通过电子传输层中金属氧族化合物传输材料和有机传输材料的共同调配作用，使电子传输层同时具有高电子迁移率以及能级匹配的灵活性。实现电子传输层的能级和电子迁移率的有效调控，从而达到与空穴注入的充分匹配。本申请实施例电子传输层可通过真空蒸镀方式或溶液法方式在发光器件中制备成薄膜；其中溶液法方式包括喷墨打印、旋涂、喷印、狭缝涂布或丝网印刷等。
在一些实施例中，有机传输材料的电子迁移率不低于10 -4cm 2/Vs。在一些实施例中，有机传输材料选自8-羟基喹啉-锂、八羟基喹啉铝、富勒烯衍生物、3,5-双(4-叔丁基苯基)-4-苯基-4H-1,2,4-三唑、1,3,5-三(1-苯基-1H-苯并咪唑-2-基)苯中的至少一种。这些有机传输材料可以在较宽的范围内实现能级的调控，更有利于调控器件各功能层能级，提高器件的稳定性和光电转化效率。
在一些实施例中，电子传输层中，还包含有金属氧族化合物传输层，其中，金属氧族化合物选自氧化钛、硫化锌、硫化镉中的至少一种。这些金属氧族化合物传输材料均具有较高的电子迁移效率。
在一些实施例中，电子传输层中，金属氧族化合物传输材料的粒径小于等于10nm，一方面，小粒径的金属氧族化合物传输材料更有利于沉积得到膜层致密、厚度均一的电子传输层薄膜，提高其与相邻功能层的结合紧密性，降低界面电阻，更有利于提高器件性能。另一方面，小粒径的金属氧族化合物传输材料带隙更宽，减小了对量子点材料的激子发光淬灭，提高器件效率。
在一些实施例中，金属氧族化合物传输材料的电子迁移率为10 -2～10 -3cm 2/Vs，高迁移率的电子传输材料，能够减少电荷在界面层的积累，提高电子注入、复合效率。
从一方面考虑，由于目前器件中空穴注入层往往是为了提高空穴的注入效率，而本申请实施例QLED器件需要通过一定的方式调控空穴注入至较低的速率。因此，在一些具体实施例中，本申请实施例第一方面提供的光电器件中可以不设置空穴注入层来增强空穴注入效率。
从另一方面考虑，QLED器件中空穴注入层的设置不仅仅可以提高空穴注入效率，同时也是调节空穴平稳、均衡注入的关键，也是影响器件的性能、寿命等性能关键因素之一。 因此，本申请实施例也可以通过在器件中设置空穴注入层调控器件中空穴注入效率，以及避免电荷积累对器件寿命的影响。具体地：
通常在QLED器件性能的研究中，更多关注的是发光层EML两侧，如HTL或ETL界面的电荷积累所造成的界面损坏，以及对于EML发光层中激子的淬灭。但实际上HIL到HTL的界面能级势垒也容易形成电荷积累，从而使得HIL与HTL之间的界面在电场的作用下发生不可逆的破坏，造成器件电压上升，器件亮度衰减。而且，此时所造成的QLED器件电压上升与在EML界面处电荷积累所造成的电压上升存在如下明显不同：HIL与HTL之间界面由于电荷积累产生电场，所造成的不可逆破坏是会随着器件持续通电一直发生的，即会持续恶化；而EML界面处的电荷积累是可逆的且会达到一定程度的饱和。因此，HIL与HTL之间界面电荷积累对器件的寿命等性能影响更大。
一方面，本申请实施例为了避免HIL与HTL界面电荷积累对器件寿命性能造成不可逆破坏，优化QLED器件内载流子的注入、复合效率。本申请实施例第二方面，在上述第一方面实施例的基础上提供一种光电器件，光电器件包括空穴传输层和第一空穴注入层，空穴传输层材料的价带顶能级与第一空穴注入层中第一空穴注入材料的功函差值的绝对值小于等于0.2eV。
本申请第二方面提供的光电器件，通过限定|ΔE HTL-HIL|小于等于0.2eV，使HTL与HIL之间的空穴注入能级势垒能够显著降低，提高空穴从阳极的注入效率，有利于空穴从HIL向HTL的有效注入，消除势垒及界面电荷，减小器件的整体电阻，从而避免在HIL和HTL之间界面处电荷积累造成不可逆破坏，降低器件驱动电压、提升器件寿命。若|ΔE HTL-HIL|大于0.2eV，则HIL到HTL的界面能级势垒容易形成电荷积累，从而使得HIL与HTL之间的界面在电场的作用下发生不可逆的破坏，造成器件电压上升，器件亮度衰减。
在一些实施例中，空穴传输层材料的价带顶能级与第一空穴注入材料的功函差值的绝对值为0eV。本申请实施例选择|ΔE HTL-HIL|为0，更有利于空穴从HIL向HTL的有效注入，消除势垒及界面电荷，减小器件的整体电阻，从而降低器件驱动电压、提升器件寿命。
在一些实施例中，第一空穴注入材料的功函绝对值为5.3eV～5.6eV，该功函大小的空穴注入材料与目前现有空穴传输材料的价带能级的绝对值比较接近(5.4eV左右)，有利于控制|ΔE HTL-HIL|在较低的范围，使两者能级基本齐平，消除势垒及界面电荷，降低器件驱动电压、提升器件寿命。本申请实施例通过选择具有合适能级的HIL和HTL材料，使|ΔE HTL-HIL|小于等于0.2eV，可以有效消除HIL到HTL的能级势垒，以及界面处的电荷积累，从而避免在HIL和HTL之间界面处造成不可逆破坏。
在一些实施例中，空穴传输材料的迁移率高于1×10 -4cm 2/Vs。本申请实施例采用迁移率高于1×10 -4cm 2/Vs的空穴传输材料，确保空穴的传输迁移效果，防止电荷积累，消除界面电荷，更好的降低器件驱动电压、提升器件寿命。
另一方面，本申请实施例为了降低QLED器件内空穴注入速率，调控载流子的注入、复合效率，同时避免HIL与HTL界面电荷积累对器件寿命性能造成不可逆破坏。本申请实施例第三方面，在上述第一方面实施例的基础上提供一种光电器件，包括空穴传输层和第二空穴注入层，空穴传输层中空穴传输层材料的价带顶能级与第二空穴注入层中第二空穴注入材料的功函差值小于-0.2eV。
本申请第三方面提供的光电器件，通过在空穴传输层材料与第二空穴注入材料之间构筑小于-0.2eV的注入势垒，即ΔE HTL-HIL＜-0.2eV，增大阳极向HIL的空穴注入势垒，从而降低QLED器件内空穴注入的整体速率，有效控制了进入QLED器件内的空穴数量。一方面，有效的减少了空穴注入到发光层内的速率，使发光层中空穴电子注入速率平衡，提高载流子复合效率；另一方面，又能避免空穴注入过多在HTL和HIL界面处形成电荷积累，防止界面电荷积累对器件寿命造成不可逆的破坏作用。同时，形成从HTL向HIL的空穴阻挡势垒，防止空穴扩散至HIL层，提高空穴的利用率，确保空穴在注入到发光层之前有效的“存活”。保证载流子在器件稳定工作状态下注入平衡的基础上，充分有效地利用器件中注入的空穴，保证器件的发光效率，实现器件效率和寿命的同时提升。
在一些实施例中，光电器件的量子点发光层中包含的核壳结构的量子点材料，其外壳层材料与空穴传输材料的价带顶能级差大于0eV，即ΔE EML-HTL＞0，发光层中存在的空穴注入势垒，与HTL和HIL之间的势垒，使传输层形成空穴载流子阱，有效地“存储”住累积的空穴而不扩散至HTL层以外的其他功能层或界面，消除界面电荷对器件的影响，在保证载流子在器件稳定工作状态下注入平衡的基础上，更充分有效地利用器件中注入的空穴，保证器件的发光效率，实现器件效率和寿命的同时提升。在一些具体实施例中，量子点材料的外壳层材料与空穴传输材料的价带顶能级差大于等于0.5eV～1.7eV，即ΔE EML-HTL为0.5eV～1.7eV，形成更好的空穴载流子阱，在实际应用过程中通过空穴载流子肼更精细的调控器件发光层中空穴与电子的注入平衡，提高载流子复合效率。
在一些实施例中，空穴传输层材料的价带顶能级与第二空穴注入材料的功函差值为-0.9eV～-0.2eV，ΔE HTL-HIL差值为-0.9eV～-0.2eV，在该范围内对空穴的注入和传输有更好的平衡效果。若低于-0.9eV，则空穴注入阻力过大，会导致空穴注入量太少，不利于发光层中空穴与电子的平衡注入以及有效复合；若势垒大于-0.2eV，则空穴容易在界面形成积累，且利用率不高。
在一些实施例中，第二空穴注入材料的功函绝对值为5.4eV～5.8eV。本申请实施例第二空穴注入材料的功函绝对值为5.4eV～5.8eV，在该范围内有利于与空穴传输材料之间形成能极差小于-0.2eV空穴阻挡势垒。具体地，常规空穴传输材料的价带绝对值大概在5.3-5.4eV，功函绝对值大于等于5.4eV的第二空穴注入材料可与常规空穴传输材料形成小于-0.2eV的负能级差，从而形成空穴阻挡势垒，优化空穴注入速率，提高空穴利用率。
在一些实施例中，空穴传输材料的迁移率高于1×10 -4cm 2/Vs，本申请实施例采用迁移率高于1×10 -4cm 2/Vs的空穴传输材料，确保空穴的传输迁移效果，防止电荷积累，消除界面电荷，更好的降低器件驱动电压、提升器件寿命。
本申请上述第二方面和第三方面实施例中，空穴注入材料选择金属氧化物材料。即，在一些具体实施例中，当光电器件包含第一空穴注入层时，第一空穴注入层中第一空穴注入材料选自金属氧化物材料。在另一些具体实施例中，当光电器件包含第二空穴注入层时，第二空穴注入层中第二空穴注入材料选自金属氧化物材料。本申请上述实施例中，空穴注入材料采用的金属氧化物材料，具有更好的稳定性，且不具有酸性，不但能满足上述各实施例对空穴注入的要求，而且不会对相邻功能层产生负面影响。避免了有机空穴注入材料在器件工作过程中由于热效应或电学效应破坏对器件寿命造成的衰减，同时避免了有机空 穴注入材料的酸性对相邻功能层的破坏作用。
在一些实施例中，金属氧化物材料包括：氧化钨、氧化钼、氧化钒、氧化镍、氧化铜中的至少一种金属纳米材料，这些金属纳米材料不但具有更好的稳定性，不具有酸性，而且在实际应用过程中可通过调控功函大小，实现与空穴传输层构筑不同大小的能级势垒，进而有利于调控空穴注入和传输，提高载流子复合效率，避免电荷积累对器件寿命的影响。
在一些实施例中，金属氧化物材料的粒径为2～10nm，小粒径的金属氧化物材料更有利于沉积得到膜层致密、厚度均一的薄膜，提高其与相邻功能层的结合紧密性，降低界面电阻，更有利于提高器件性能。
在另一些实施例中，空穴注入材料也可以采用聚(3,4-乙烯二氧噻吩)-聚苯乙烯磺酸(PEDOT:PSS)、HIL2、HIL1-1、HIL1-2、酞菁铜(CuPc)、2,3,5,6-四氟-7,7',8,8'-四氰醌-二甲烷(F4-TCNQ)、2,3,6,7,10,11-六氰基-1,4,5,8,9,12-六氮杂苯并菲(HATCN)等有机空穴注入材料。其中，PEDOT:PSS包含结构式为：
Figure PCTCN2021141746-appb-000001
的有机分子，其功函为-5.1eV；HIL2包含结构式为：
Figure PCTCN2021141746-appb-000002
的有机分子，其功函为-5.6eV；HIL1-1和HIL1-2中均包含结构式为：
Figure PCTCN2021141746-appb-000003
Figure PCTCN2021141746-appb-000004
的有机分子，HIL1-1的功函为-5.4eV，HIL1-2的功函为-5.3eV。
在一些实施例中，第一空穴注入层的厚度为10～150nm。在另一些实施例中，第二空穴注入层的厚度为10～150nm。本申请空穴注入层的厚度可根据实际应用需求进行灵活调控，同时也可通过对空穴注入层厚度的调节更好的实现对空穴注入速率的调节。
在一些实施例中，空穴传输材料选自TFB、poly-TPD、P11、P09、P13、P15、P12中的至少一种。在另一些实施例中，空穴传输材料的迁移率高于1×10 -4cm 2/Vs。本申请上述实施例提供的空穴传输材料不但能与量子点材料的外壳层材料构建能级差大于等于0.5eV空穴注入势垒，而且有效确保了空穴的迁移速率，避免迁移速率慢导致的电荷积累，提高器件的使用寿命。具体地，本申请实施例为了构筑ΔE EML-HTL大于等于0.5eV的能级势垒，实现降低QLED器件内空穴注入速率，调控载流子的注入、复合效率的目的，同时避免HIL与HTL界面电荷积累对器件寿命性能造成不可逆破坏。在一些实施例中，本申请第四方面提供一种光电器件，该光电器件的空穴传输层中至少包含两种空穴传输材料，其中，至少一种空穴传输材料的价带顶能级的绝对值小于等于5.3eV，至少一种空穴传输材料的价带顶 能级的绝对值大于5.3eV。
本申请第四方面提供的光电器件的空穴传输层为混合材料，其中至少一种空穴传输材料的价带顶能级小于等于5.3eV，而常规量子点发光材料的壳层能级往往比较深(6.0eV或更深)，因此，使得浅能级的空穴传输材料与量子点外壳材料之间形成大于等于0.5eV的能级差。空穴传输层中通过浅能级材料、深能级材料之间的相互搭配，可实现对空穴传输材料与量子点外壳层之间的空穴注入势垒的精细调控，同时也可以通过不同能级深浅的空穴传输材料调节HTL层中空穴迁移率。实现ΔE EML-HTL大于等于0.5eV的能级势垒，通过提高空穴注入势垒，降低空穴的注入效率，从而平衡发光层中空穴与电子的注入平衡，提高器件发光效率，同时避免电荷积累对器件寿命的影响。
在一些实施例中，空穴传输层中还包括价带顶能级的绝对值大于5.3eV小于5.8eV的空穴传输材料。在一些实施例中，空穴传输层中还包括价带顶能级的绝对值大于等于5.8eV的空穴传输材料。在另一些实施例中，空穴传输层中，同时包括价带顶能级的绝对值大于5.3eV小于5.8eV的空穴传输材料和价带顶能级的绝对值大于等于5.8eV的空穴传输材料。本申请实施例通过浅能级材料和深能级材料的混合匹配，可根据实际应用需求、器件体系等因素灵活调控空穴注入势垒，使空穴到发光材料的注入能级势垒大于等于0.5eV，降低空穴的注入效率，从而平衡发光层中空穴与电子的注入平衡，应用灵活方便。
在一些实施例中，当空穴传输层中包括价带顶能级大于5.3eV小于5.8eV的空穴传输材料时，光电器件的电子传输层中选择包括：有机电子传输材料层、ZnO纳米颗粒等金属氧化物纳米颗粒层、溅射沉积的金属氧化物层中的至少一种。本申请实施例当空穴传输层中包括至少一种空穴传输材料的价带顶能级小于等于5.3eV和价带顶能级大于5.3eV小于5.8eV的空穴传输材料时，此时空穴传输层具有较为适中的价带顶能级和空穴迁移率，因此可以较好地与ZnO等常规金属氧化物或有机电子传输材料相匹配，有利于空穴与电子电荷平衡的调控。
在一些实施例中，当空穴传输层中包括价带顶能级大于等于5.8eV的空穴传输材料时，光电器件的电子传输层中选择包括：金属氧化物纳米颗粒，选择表面基团连接较少的金属氧化物纳米颗粒。本申请实施例当空穴传输层中包括价带顶能级大于5.8eV的空穴传输材料时，此时在能级和迁移率两个性能上均与前述空穴传输材料的价带顶能级小于等于5.3eV的浅价带顶能级的空穴传输层材料具有较大的差异，通过不同的混合比例可以实现在较大窗口范围内的连续调控，适合于从器件初始状态到持续工作至稳定状态过程中电子注入和传输变化差异性较大的QLED器件体系，例如表面基团连接较少的金属氧化物纳米颗粒。
在一些实施例中，空穴传输层中，价带顶能级的绝对值小于等于5.3eV的空穴传输材料的质量百分含量为30～90％；浅能级空穴传输材料的该百分含量，确保能与发光材料的外壳层形成大于等于0.5eV的空穴注入势垒，在实际应用中，可根据材料能级深浅，灵活调控各能级大小材料的混合比例。
在一些实施例中，空穴传输层中，至少一种空穴传输材料的迁移率高于1×10 -3cm 2/Vs，本申请实施例空穴传输材料的高迁移率确保了空穴的传输迁移性能，避免空穴在界面积累导致影响器件性能。另外，高空穴迁移率的空穴传输层材料其价带顶能级相对比较浅，也确保了与量子点外壳材料之间形成合适的能极差。
在一些具体实施例中，空穴传输层中至少一种空穴传输材料的迁移率高于1×10 -2cm 2/Vs。在另一些具体实施例中，空穴传输层中，每一种空穴传输材料的迁移率均高于1×10 -3cm 2/Vs。本申请上述实施例通过优化空穴传输材料的迁移率，同时确保空穴的迁移效率，避免电荷积累影响器件性能，同时确保空穴传输层中深浅能级的空穴传输材料的搭配，构筑空穴的注入势垒，确保形成ΔE EML-HTL大于等于0.5eV的能级势垒，优化QLED器件内载流子的注入平衡和复合效率。
在一些实施例中，本申请实施例为了构筑ΔE EML-HTL大于等于0.5eV的能级势垒，实现降低QLED器件内空穴注入速率，调控载流子的注入、复合效率的目的，同时避免HIL与HTL界面电荷积累对器件寿命性能造成不可逆破坏。在一些实施例中，本申请第五方面提供一种光电器件，该光电器件的空穴传输层中至少包含两种空穴传输材料，空穴传输材料的价带顶能级的绝对值均小于等于5.3eV。
本申请第五方面提供的光电器件的空穴传输层为混合材料，空穴传输材料的价带顶能级均小于等于5.3eV，与壳层能级较深的量子点发光材料可形成大于等于0.5eV的能级差。实现对于构造HTL与EML中量子点外壳层之间的空穴注入势垒更精细的调控，使器件ΔE EML-HTL≥0.5eV。从而实现QLED器件在进入稳定工作状态后，电荷注入平衡以及器件效率保持，实现器件寿命的最优化。另外，利用同样都为具有浅价带顶能级的空穴传输层材料的不同空穴迁移率，通过不同混合比例还可以对混合空穴传输层的空穴迁移率进行精细调控。
在一些实施例中，空穴传输层中，每一种空穴传输材料的质量百分含量为5～95％，通过不同能级深浅、迁移率大小的空穴传输材料混合搭配，对混合空穴传输层的空穴迁移率和注入势垒有更好的调控效果。
在一些实施例中，空穴传输层中，至少一种空穴传输材料的迁移率高于1×10 -3cm 2/Vs，高空穴迁移率的空穴传输层材料其价带顶能级相对比较浅。限定空穴传输材料的迁移率，高迁移率确保了空穴的传输迁移性能，同时确保了形成更合适的注入势垒，避免空穴在界面积累导致影响器件性能。在一些实施例中，空穴传输层中至少一种空穴传输材料的迁移率高于1×10 -2cm 2/Vs。在一些实施例中，空穴传输层中，每一种空穴传输材料的迁移率均高于1×10 -3cm 2/Vs。
在一些实施例中，当空穴传输层中空穴传输材料的价带顶能级均小于等于5.3eV时，光电器件的电子传输层中选择包括：表面钝化的金属氧化物纳米颗粒，选择表面充分修饰钝化的金属氧化物纳米颗粒。本申请实施例当空穴传输层中空穴传输材料的价带顶能级均小于等于5.3eV时，要对应电子注入和传输变化小的材料，此时适合于从器件初始状态到持续工作至稳定状态过程中电子注入和传输变化差异性较小的QLED器件体系，例如表面充分修饰钝化的金属氧化物纳米颗粒。
本申请上述各实施例的光电器件中，空穴传输材料选自含苯胺基团的聚合物、含有芴基团和苯胺基团的共聚物中的至少一种，这些空穴传输材料具有空穴传输效率高，稳定性好，容易获取等优点。在实际应用过程中，可根据实际应用需求，选择合适能级大小、迁移率的空穴传输材料，具体地：
在一些具体实施例中，当光电器件中需要价带顶能级的绝对值小于等于5.3eV的空穴 材料时，价带顶能级的绝对值小于等于5.3eV的空穴传输材料可选择：P09、P13中的至少一种。其中，P13的结构式为：
Figure PCTCN2021141746-appb-000005
P09的结构式为：
Figure PCTCN2021141746-appb-000006
在另一些具体实施例中，当光电器件中需要价带顶能级的绝对值大于5.3eV小于5.8eV的空穴材料时，价带顶能级的绝对值大于5.3eV小于5.8eV的空穴传输材料包括：TFB、poly-TPD、P11中的至少一种。其中，P11的结构式为：
Figure PCTCN2021141746-appb-000007
poly-TPD的结构式为：
Figure PCTCN2021141746-appb-000008
TFB的结构式为：
Figure PCTCN2021141746-appb-000009
在另一些具体实施例中，当光电器件中需要价带顶能级的绝对值大于等于5.8eV的空穴材料时，价带顶能级的绝对值大于等于5.8eV的空穴传输材料包括：P15、P12中的至少 一种。其中，P12的结构式为：
Figure PCTCN2021141746-appb-000010
P15的结构式为：
Figure PCTCN2021141746-appb-000011
在一些实施例中，空穴传输材料的迁移率高于1×10 -4cm 2/Vs，高迁移率确保了空穴的传输迁移性能，避免电荷积累对器件寿命的影响。
本申请上述各实施例中，核壳结构的量子点材料还包括内核，以及位于内核与外壳层之间的中间壳层；其中，内核材料的价带顶能级浅于外壳层材料的价带顶能级；中间壳层材料的价带顶能级介于内核材料的价带顶能级和外壳层材料的价带顶能级之间。本申请实施例核壳结构的量子点材料中，内核材料决定发光性能，外壳材料起到保护和利于载流子注入作用，价带介于内核与外壳层之间的中间壳层，起到中间过渡作用，更有利于载流子注入，中间壳层在能级上可形成从内核到外壳层的阶梯式能级过渡，这样有助于实现载流子的有效注入、有效束缚以及减少晶格界面的闪烁。
在一些实施例中，量子点材料的外壳层包括：CdS、ZnSe、ZnTe、ZnS、ZnSeS、CdZnS、PbS中的至少一种或者至少两种形成的合金材料。这些外壳层材料不但保护和利于载流子注入到量子点内核进行发光，而且能与HTL层材料形成ΔE EML-HTL大于等于0.5eV的能级势垒，通过提高空穴注入势垒，降低空穴的注入效率，从而平衡发光层中空穴与电子的注入平衡，提高器件发光效率，同时避免电荷积累对器件寿命的影响。
在一些实施例中，量子点材料的内核包括：CdSe、CdZnSe、CdZnS、CdSeS、CdZnSeS、InP、InGaP、GaN、GaP、ZnSe、ZnTe、ZnTeSe中的至少一种。量子点材料的发光性能与内核材料相关，这些材料确保了QLED器件在400～700nm可见光范围内实现发光，不但满足光电显示器件应用所需的范围，而且这些材料能级相互关系实现的有益效果能够更好地体现。
在一些实施例中，中间壳层材料选自CdZnSe、ZnSe、CdZnS、CdZnSeS、CdS、CdSeS中的至少一种。本申请实施例选择的，中间壳层在组成成分上最好是形成从内核到外层的 组成成分连续自然过渡，这样有助于实现内核、中间壳层、外壳层三者之间最少的晶格失配及最少的晶格缺陷，从而实现核壳量子点材料自身最优的发光性能。
在一些实施例中，量子点材料的发光峰波长范围为400～700nm，一方面这个波长范围是光电显示器件应用所需的范围，另一方面器件中发光层在此波长范围能级相互关系实现的有益效果能够更好地体现。
在一些实施例中，量子点材料的外壳层厚度为0.2～6.0nm，该厚度涵盖了常规外壳的厚度，可广泛是适用于不同体系的QLED器件中。若外壳层的厚度过大时，载流子通过隧穿效应注入到发光量子点的速率会降低；而外壳层的厚度过小时，外壳材料无法对内核材料起到足够的保护作用和钝化作用，影响量子点材料的发光性能和稳定性能。
本申请上述各实施例中，光电器件还包括电子传输层，电子传输层中电子传输材料选自金属氧族化合物传输材料、有机传输材料中的至少一种。其中，金属氧化物材料一般来说具有较高的电子迁移率，可通过溶液法方式或真空溅射方式在QLED器件中制备成薄膜。有机电子传输层材料可以在较宽的范围内实现能级的调控，可通过真空蒸镀方式或溶液法方式在QLED器件中制备成薄膜；其中溶液法方式包括喷墨打印、旋涂、喷印、狭缝涂布或丝网印刷等。可根据实际应用需求灵活选择更合适的电子传输材料。
在一些实施例中，金属氧族化合物传输材料选自氧化锌、氧化钛、硫化锌、硫化镉中的至少一种。本申请上述实施例采用的这些金属氧族化合物传输材料均具有较高的电子迁移效率。在一些实施例中，为提高电子迁移效率，金属氧族化合物传输材料选自掺杂有金属元素的氧化锌、氧化钛、硫化锌、硫化镉中的至少一种，其中，金属元素包括铝、镁、锂、镧、钇、锰、镓、铁、铬、钴中至少一种，这些金属元素可提高材料的电子迁移效率。
在一些实施例中，金属氧族化合物传输材料的粒径小于等于10nm，一方面，小粒径的金属氧族化合物传输材料更有利于沉积得到膜层致密、厚度均一的电子传输层薄膜，提高其与相邻功能层的结合紧密性，降低界面电阻，更有利于提高器件性能。另一方面，小粒径的金属氧族化合物传输材料带隙更宽，减小了对量子点材料的激子发光淬灭，提高器件效率。
在一些实施例中，金属氧族化合物传输材料的电子迁移率为10 -2～10 -3cm 2/Vs，高迁移率的电子传输材料，能够减少电荷在界面层的积累，提高电子注入、复合效率。
在一些实施例中，有机传输材料的电子迁移率不低于10 -4cm 2/Vs。在一些实施例中，有机传输材料选自NaF、LiF、CsF、8-羟基喹啉-锂、Cs 2CO 3、Alq 3中的至少一种。这些有机传输材料可以在较宽的范围内实现能级的调控，更有利于调控器件各功能层能级，提高器件的稳定性和光电转化效率。
在一些实施例中，电子传输层为叠层复合结构，其中包括至少两层子电子传输层，通过选择不同传输迁移效率、能级调控特性的子电子传输层，可更灵活的调控电子传输层性，从而更好的优化器件性能。
在一些实施例中，电子传输层中，至少一层子电子传输层的材料为金属氧族化合物传输材料。在一些实施例中，电子传输层中，所有子电子传输层均为金属氧化物，不同子电子传输层的金属氧化物材料可以相同或不同。即在所有子电子传输层均为金属氧化物的多层电子传输层中，可以为包含至少一层的金属氧化物纳米颗粒的子电子传输层以及至少一 层的非纳米颗粒类型金属氧化物的子电子传输层。也可以为子电子传输层分别是掺杂和本征金属氧化物(如Mg掺杂ZnO+本征ZnO)。也可以为子电子传输层均为同一种金属氧化物纳米颗粒。当子电子传输层均为同一种金属氧化物纳米颗粒时，不同子电子传输层的电子迁移率可以相同或不相同。
在一些实施例中，电子传输层中，至少一层子电子传输层的材料为有机传输材料。在一些实施例中，电子传输层中，至少一层子电子传输层的材料为金属氧族化合物传输材料，至少一层子电子传输层的材料为有机传输材料，不同子电子传输层的金属氧化物材料可以相同或不同；的金属氧化物材料选择为相应金属氧化物的纳米颗粒。通过电子传输层中金属氧族化合物传输材料和有机传输材料的共同调配作用，使电子传输层同时具有高电子迁移率以及能级匹配的灵活性。实现电子传输层的能级和电子迁移率的有效调控，从而达到与空穴注入的充分匹配。在一些具体实施例中，包含多层子电子传输层的电子传输层可以是ZnO纳米颗粒+NaF的组合、Mg掺杂ZnO纳米颗粒+NaF的组合等叠层复合结构。
由于核壳结构的量子点材料中，内核材料决定量子点材料的发光性能，壳层材料起到保护作用，以及有利于载流子注入。当外壳层材料确定后，可以通过调节壳层厚度以及空穴传输材料的价带顶能级大小等，使量子点材料的外壳层材料与空穴传输材料之间价带顶能级差大于等于0.5eV，即构建预期的注入势垒，E EML-HTL≥0.5eV，优化发光层中电子与空穴注入效率平衡，提高器件效率和使用寿命。
本申请上述各实施例中，器件不受器件结构的限制，可以是正型结构的器件，也可以反型结构的器件。
在一种实施方式中，正型结构光电器件包括相对设置的阳极和阴极的层叠结构，设置在阳极和阴极之间的发光层，且阳极设置在衬底上。在一些实施例中，阳极和发光层之间还可以设置空穴注入层、空穴传输层等空穴功能层；在阴极和发光层之间还可以设置电子传输层、电子注入层等电子功能层，如附图2所示。在一些具体正型结构器件的实施例中，光电器件包括衬底，设置在衬底表面的阳极，设置在阳极表面的空穴传输层，设置在空穴传输层表面的发光层，设置在发光层表面的电子传输层和设置在电子传输层表面的阴极。
在一种实施方式中，反型结构光电器件包括相对设置的阳极和阴极的叠层结构，设置在阳极和阴极之间的发光层，且阴极设置在衬底上。阳极和发光层之间还可以设置空穴注入层、空穴传输层等空穴功能层；在阴极和发光层之间还可以设置电子传输层、电子注入层等电子功能层，如附图3所示。在一些反型结构器件的实施例中，光电器件包括衬底，设置在衬底表面的阴极，设置在阴极表面的电子传输层，设置在电子传输层表面的发光层，设置在发光层表面的空穴传输层，设置在空穴传输层表面的阳极。
在一些实施例中，衬底的选用不受限制，可以采用刚性基板，也可以采用柔性基板。在一些具体实施例中，刚性基板包括但不限于玻璃、金属箔片中的一种或多种。在一些具体实施例中，柔性基板包括但不限于聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸乙二醇酯(PEN)、聚醚醚酮(PEEK)、聚苯乙烯(PS)、聚醚砜(PES)、聚碳酸酯(PC)、聚芳基酸酯(PAT)、聚芳酯(PAR)、聚酰亚胺(PI)、聚氯乙烯(PV)、聚乙烯(PE)、聚乙烯吡咯烷酮(PVP)、纺织纤维中的一种或多种。
在一些实施例中，阳极材料的选用不受限制，可选自掺杂金属氧化物，包括但不限于 铟掺杂氧化锡(ITO)、氟掺杂氧化锡(FTO)、锑掺杂氧化锡(ATO)、铝掺杂氧化锌(AZO)、镓掺杂氧化锌(GZO)、铟掺杂氧化锌(IZO)、镁掺杂氧化锌(MZO)、铝掺杂氧化镁(AMO)中的一种或多种。也可以选自掺杂或非掺杂的透明金属氧化物之间夹着金属的复合电极，包括但不限于AZO/Ag/AZO、AZO/Al/AZO、ITO/Ag/ITO、ITO/Al/ITO、ZnO/Ag/ZnO、ZnO/Al/ZnO、TiO 2/Ag/TiO 2、TiO 2/Al/TiO 2、ZnS/Ag/ZnS、ZnS/Al/ZnS、TiO 2/Ag/TiO 2、TiO 2/Al/TiO 2中的一种或多种。
在一些实施例中，阴极材料可以是各种导电碳材料、导电金属氧化物材料、金属材料中的一种或多种。在一些具体实施例中，导电碳材料包括但不限于掺杂或非掺杂碳纳米管、掺杂或非掺杂石墨烯、掺杂或非掺杂氧化石墨烯、C60、石墨、碳纤维、多空碳、或它们的混合物。在一些具体实施例中，导电金属氧化物材料包括但不限于ITO、FTO、ATO、AZO、或它们的混合物。在一些具体实施例中，金属材料包括但不限于Al、Ag、Cu、Mo、Au、或它们的合金；其中的金属材料中，其形态包括但不限于致密薄膜、纳米线、纳米球、纳米棒、纳米锥、纳米空心球、或它们的混合物；阴极为Ag、Al。
在一些实施例中，量子点发光层的厚度为8～100nm。在一些实施例中，空穴传输层的厚度为10～150nm。在一些实施例中，电子传输层的厚度为10～200nm。在实际应用中，器件中的电子功能层、发光层、空穴功能层可根据上述各实施例中器件的特性对应设计合适的功能层。
本申请实施例光电器件的制备包括步骤：
S10.获取沉积有阳极的基板；
S20.在阳极表面生长一空穴注入层；
S30.在空穴注入层表面生长一空穴传输层；
S40.接着沉积量子点发光层于空穴传输层上；
S50.最后沉积电子传输层于量子点发光层上，并蒸镀阴极于电子传输层上，得到光电器件。
具体地，步骤S10中，ITO基底需要经过预处理过程，步骤包括：将ITO导电玻璃用清洁剂清洗，初步去除表面存在的污渍，随后依次在去离子水、丙酮、无水乙醇、去离子水中分别超声清洗20min，以除去表面存在的杂质，最后用高纯氮气吹干，即可得到ITO正极。
具体地，步骤S20中，生长空穴注入层的步骤包括：将金属氧化物等材料通过溶液法方式、真空溅射方式、真空蒸镀方式在QLED器件中制备成薄膜；其中，溶液法的方式包括喷墨打印、旋涂、喷印(spray printing)、狭缝涂布(slot-die printing)或丝网印刷(screen printing)等。
具体地，步骤S30中，生长空穴传输层的步骤包括：将ITO基板置于旋涂仪上，用配制好的空穴传输材料的溶液旋涂成膜；通过调节溶液的浓度、旋涂速度和旋涂时间来控制膜厚，然后在适当温度下热退火处理。
具体地，步骤S40中，沉积量子点发光层于空穴传输层上的步骤包括：将已旋涂上空穴传输层的基片置于旋涂仪上，将配制好一定浓度的发光物质溶液旋涂成膜，通过调节溶液的浓度、旋涂速度和旋涂时间来控制发光层的厚度，约20～60nm，在适当温度下干燥。
具体地，步骤S50中，沉积电子传输层于量子点发光层上的步骤包括：将已旋涂上量子点发光层的基片置于旋涂仪上，将配制好一定浓度的电子传输复合材料溶液通过滴涂、旋涂、浸泡、涂布、打印、蒸镀等工艺旋涂成膜，通过调节溶液的浓度、旋涂速度(例如，转速在3000～5000rpm之间)和旋涂时间来控制电子传输层的厚度，约20～60nm，然后在150℃～200℃的条件下退火成膜，充分去除溶剂。
具体地，步骤S50中，阴极制备的步骤包括：将沉积完各功能层的衬底置于蒸镀仓中通过掩膜板热蒸镀一层60-100nm的金属银或者铝作为阴极。
在一些实施例中，光电器件的制备方法，还包括对层叠制备的光电器件进行封装；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。封装处理可采用常用的机器封装，也可以采用手动封装。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。
在一些实施例中，光电器件的制备方法，还包括在对光电器件进行封装后，引入包括紫外照射、加热、正负压力、外加电场、外加磁场在内的一种或多种工艺；施加工艺时的气氛可以为空气或惰性气氛。
为使本申请上述实施细节和操作能清楚地被本领域技术人员理解，以及本申请实施例光电器件的进步性能显著的体现，以下通过多个实施例来举例说明上述技术方案。
本申请实施例器件均采用ITO/HIL/HTL/QD/ETL/AL结构，封装后进行一定的加热处理，通过对器件中不同功能层的搭配对比，来说明详细说明本申请技术方案的优势。在下列实施例中，寿命测试采用恒流法，在恒定50mA/cm 2电流驱动下，采用硅光系统测试器件亮度变化，记录器件亮度从最高点开始，衰减到最高亮度95％的时间LT95，再通过经验公式外推器件1000nit LT95S寿命。此方法便于不同亮度水平器件的寿命比较，在实际光电器件中有着广泛的应用。
1000nit LT95＝(L Max/1000) 1.7×LT95
本申请实施例中各材料能级测试方法：将各功能层材料进行旋涂成膜后，采用UPS(紫外光电子能谱)的方法进行能级测试。
功函数Φ＝hν-E cutoff，其中hv为入射激发光子的能量，E cutoff为激发的二次电子截止位置；
价带顶VB(HOMO)：E HOMO＝E F-HOMO+Φ，其中E F-HOMO为材料HOMO(VB)与费米能级差值，对应结合能谱中低结合能端出现的第一个峰的起始边；
导带底(LOMO)：E LOMO＝E HOMO-E HOMO-LOMO，其中，E HOMO-LOMO为材料的带隙，由UV-Vis(紫外吸收谱)得到。
实施例1～11
为验证量子点材料的外壳层材料与空穴传输材料之间的空穴注入势垒对器件性能的影响，本申请设置了实施例1～11，通过不同HTL和QD的搭配对比，来说明空穴注入势垒对器件寿命等性能的影响。
本申请实施例1～11中采用的两种量子点为：外壳为CdZnS的蓝色QD1(内核为CdZnSe，中间壳层为ZnSe，外壳厚度为1.5nm，价带顶能级为6.2eV)、外壳为ZnS的蓝色QD2(内 核为CdZnSe，中间壳层为ZnSe，ZnS外壳厚度为0.3nm，价带顶能级为6.5eV)。外壳为ZnSeS的蓝色QD3(内核为CdZnSe，中间壳层为ZnSe)空穴传输材料分别为P9(E HOMO:5.1eV)、P15(E HOMO:5.8eV)，空穴注入层采用PEDOT:PSS(E HOMO:5.1eV)，电子传输层采用表面结合有链长为3～8个碳原子的胺基/羧基配体的ZnO纳米材料，采用胺基/羧基配体化合物(Ligand)与氧化锌前驱体(Precursor)通过溶胶凝胶法制得，具体如下表1所示：
表1
Figure PCTCN2021141746-appb-000012
由上表1的测试结果可知，对于同一CdZnS(6.2eV)外壳量子点，将HTL从P15(5.8eV)改为P9(5.1eV)，ΔE EML-HTL势垒差从0.4eV增大至1.1eV，器件寿命得到提高，1000nit LT95S寿命从0.72提高到1.26。另外，对于同一P15(5.8eV)材料，改变量子点外壳，从CdZnS(6.2eV)改为ZnS(6.5eV)，ΔE EML-HTL势垒差从0.4eV增大至0.7eV，器件寿命得到显著提高，1000nit LT95S寿命从0.72提高到6.29。
由此可见，无论是调整HTL或者EML材料，使价带顶能级差ΔE EML-HTL增大到0.5eV以上，器件注入平衡得到优化，器件寿命都能得到增强。说明通过提高空穴注入势垒来降低空穴的注入效率，能够更好的平衡发光层中空穴与电子的注入平衡，提高器件发光效率和发光寿命。另外，通过实施例7～11可知，当ZnO表面结合配体碳链为3～8时，对器件性能有更优的促进作用。
实施例12～15
为验证HIL到HTL的界面能级势垒对器件性能的影响，本申请设置了实施例12～15，通过不同HTL和HTL的搭配对比，来说明ΔE HTL-HIL空穴注入势垒对器件寿命等性能的影 响。
本申请实施例12～13中采用外壳为ZnS的蓝色量子点(内核为CdZnSe，中间壳层为ZnSe，外壳厚度为0.3nm，价带顶能级为6.5eV)，实施例14～15中采用外壳为ZnS的红色量子点(内核为CdZnSe，中间壳层为ZnSe，外壳厚度为0.3nm，价带顶能级为6.5eV)，空穴传输材料分别为P9(E HOMO:5.5eV)、P11(E HOMO:5.5eV)、P13(E HOMO:4.9eV)，空穴注入层采用PEDOT:PSS(E HOMO:5.1eV)和HIL2(功函:5.6eV)，电子传输层采用表面结合有丙胺配体的ZnO纳米材料，按配体化合物(Ligand)与氧化锌前驱体(Precursor)的摩尔比为6:1通过溶胶凝胶法制得，具体如下表2所示：
表2
Figure PCTCN2021141746-appb-000013
注释：当ΔE HTL-HIL＜0.2eV时，在现有的HIL材料和实验数据下，ΔE EML-HTL必然是大于0.5eV的。
由上述表2的测试结果可知，实施例12和13蓝色量子点器件相对较，以及实施例14与15红色量子点器件相对较，当HTL与HIL之间的空穴注入能级势垒ΔE HTL-HIL＜-0.2eV时，相对于ΔE HTL-HIL大于等于-0.2eV的实施例，器件寿命1000nit LT95S得到提高。说明增大阳极向HIL的空穴注入势垒，降低了QLED器件内空穴注入的整体速率，有效控制了进入QLED器件内的空穴数量，不但提高载流子复合效率；而且避免了空穴注入过多在HTL和HIL界面处形成电荷积累，提高了器件的发光寿命。
实施例16～23
为验证HIL到HTL的界面能级势垒对器件性能的影响，本申请设置了实施例16～23，通过不同HTL和HTL的搭配对比，来说明|ΔE HTL-HIL|空穴注入势垒对器件驱动电压等性能的影响。
本申请实施例16～18中采用外壳为ZnS的蓝色量子点(内核为CdZnSe，中间壳层为ZnSe，外壳厚度为0.3nm，价带顶能级为6.5eV)，实施例19～23中采用外壳为ZnS的红色量子点(内核为CdZnSe，中间壳层为ZnSe，外壳厚度为0.3nm，价带顶能级为6.5eV)，空穴传输材料分别为P9(E HOMO:5.5eV)、P13(E HOMO:4.9eV)、TFB(E HOMO:5.4eV)，空穴注入层采用PEDOT:PSS(E HOMO:5.1eV)、HIL1-1(功函:5.4eV)和HIL1-2(功函:5.3eV)，电子传输层采用表面结合有丙胺配体的ZnO纳米材料，按配体化合物(Ligand)与氧化锌前驱体(Precursor)的摩尔比为6:1通过溶胶凝胶法制得，具体如下表3所示：
表3
Figure PCTCN2021141746-appb-000014
Figure PCTCN2021141746-appb-000015
由上述表3的测试结果可知，当HTL与HIL之间的空穴注入能级势垒|ΔE HTL-HIL|小于等于0.2eV时，相对于|ΔE HTL-HIL|大于0.2的实施例，器件空穴传输侧的电荷积累很小，器件长时间恒流工作下，器件的驱动电压涨幅明显减小，器件寿命1000nit LT95S得到提高。同时，当HIL和HTL间的势垒差很小时，界面几乎无电荷积累，对侧无老化，器件的空穴注入能力稳定，器件的寿命也得到提升。说明降低空穴注入能级势垒，有利于空穴从HIL向HTL的有效注入，消除势垒及界面电荷，减小器件的整体电阻，从而提高器件的寿命。
实施例24～28
为了验证空穴注入层对器件性能的影响，本申请设置如下实施例。实施例24～26中，采用外壳为ZnS的红色量子点(内核为CdZnSe，中间壳层为ZnSe，价带顶能级为6.5eV)。实施例27～28中，采用外壳为ZnS的红色量子点(内核为CdZnSe，中间壳层为ZnSe，价带顶能级为6.5eV)。电子传输层采用表面结合有丙胺配体的ZnO纳米材料，按配体化合物(Ligand)与氧化锌前驱体(Precursor)的摩尔比为6:1通过溶胶凝胶法制得。如表4所示：
表4
Figure PCTCN2021141746-appb-000016
由上述表4测试结果可知，当器件去掉HIL层后，空穴注入层和空穴传输层间的电荷 积累和酸性PEDOT对器件的影响消失，在器件长时间恒流工作下，器件的驱动电压几乎不变，甚至因为电荷填补了器件内的缺陷，器件驱动电压有下降趋势。采用迁移率更高的P11材料，制备无HIL器件后，器件长时间恒流工作下，器件的驱动电压下降更明显，说明选择的HTL迁移率高于1x10 -3cm 2/Vs,可取得更优的抑制器件电压上涨的效果。
另外，当使用无机金属氧化物MoO 3代替有机的PEDOT:PSS作为空穴注入层材料后，由于MoO 3空穴注入材料的破坏被有效抑制，使得器件在工作工程中的电压上升相比于有机空穴注入层材料器件有着显著的降低，同时器件寿命的实测时长也得到了有效的提升。
以上仅为本申请的可选实施例而已，并不用于限制本申请。对于本领域的技术人员来说，本申请可以有各种更改和变化。凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的权利要求范围之内。

Claims (18)

  1. 一种光电器件，其特征在于，包括：阳极、在所述阳极上的空穴传输层、在所述空穴传输层上的量子点发光层，在所述量子点发光层上的电子传输层，和在所述电子传输层上的阴极；其中，所述量子点发光层中包括核壳结构的量子点材料，所述量子点材料的外壳层材料与所述空穴传输层中空穴传输材料的价带顶能级差大于等于0.5eV；所述电子传输层中包含有氧化锌纳米材料，所述氧化锌纳米材料的表面结合有链长为3～8个碳原子的胺基/羧基配体。
  2. 如权利要求1所述的光电器件，其特征在于，所述量子点材料的外壳层材料与所述空穴传输材料的价带顶能级差为0.5eV～0.7eV。
  3. 如权利要求1所述的光电器件，其特征在于，所述量子点材料的外壳层材料与所述空穴传输材料的价带顶能级差为0.7eV～1.0eV。
  4. 如权利要求1所述的光电器件，其特征在于，所述量子点材料的外壳层材料与所述空穴传输材料的价带顶能级差为1.0eV～1.4eV。
  5. 如权利要求1所述的光电器件，其特征在于，所述量子点材料的外壳层材料与所述空穴传输材料的价带顶能级差大于1.4eV～1.7eV。
  6. 如权利要求1～5任一项所述的光电器件，其特征在于，所述氧化锌纳米材料，按胺基/羧基配体化合物与氧化锌前驱体的摩尔比为(1～10)：1，通过溶胶凝胶法制得。
  7. 如权利要求6所述的光电器件，其特征在于，所述胺基/羧基配体化合物选自丙酸、丙胺、丁酸、丁胺、己酸、己胺、戊胺、辛胺中的至少一种。
  8. 如权利要求6所述的光电器件，其特征在于，所述氧化锌前驱体选自醋酸锌、硝酸锌、硫酸锌、氯化锌中至少一种。
  9. 如权利要求7或8所述的光电器件，其特征在于，当所述胺基/羧基配体化合物的链长为3～4个碳原子时，按所述胺基/羧基配体化合物与所述氧化锌前驱体的摩尔比为(4～10)：1，制备所述氧化锌纳米材料；
    当所述胺基/羧基配体化合物的链长为5～7个碳原子时，按所述胺基/羧基配体化合物与所述氧化锌前驱体的摩尔比为(1～5)：1，制备所述氧化锌纳米材料。
  10. 如权利要求1所述的光电器件，其特征在于，所述空穴传输材料选自TFB、poly-TPD、P11、P09、P13、P15、P12中的至少一种。
  11. 如权利要求1所述的光电器件，其特征在于，所述空穴传输材料的迁移率高于1×10-4cm2/Vs。
  12. 如权利要求10或11所述的光电器件，其特征在于，所述光电器件还包括空穴注入层，所述空穴注入层位于所述阳极层和所述空穴传输层之间，所述空穴传输层材料的价带顶能级与所述空穴注入层中空穴注入材料的功函差值小于-0.2eV或者功函差值的绝对值小于等于0.2eV。
  13. 如权利要求12所述的光电器件，其特征在于，当所述空穴传输层材料的价带顶能级与所述空穴注入材料的功函差值小于-0.2eV时，所述空穴注入材料的功函绝对值为5.4eV～5.8eV；
    当所述空穴传输层材料的价带顶能级与所述空穴注入材料的功函差值的绝对值小于等于0.2eV时，所述空穴注入材料的功函绝对值为5.3eV～5.6eV。
  14. 如权利要求13所述的光电器件，其特征在于，所述空穴注入材料选自氧化钨、氧化钼、氧化钒、氧化镍、氧化铜中的至少一种金属纳米材料。
  15. 如权利要求1所述的光电器件，其特征在于，所述核壳结构的量子点材料还包括内核，以及位于所述内核与所述外壳层之间的中间壳层。
  16. 如权利要求15所述的光电器件，其特征在于，所述量子点材料的外壳层包括：CdS、ZnSe、ZnTe、ZnS、ZnSeS、CdZnS、PbS中的至少一种或者至少两种形成的合金材料。
  17. 如权利要求15所述的光电器件，其特征在于，所述量子点材料的内核包括：CdSe、CdZnSe、CdZnS、CdSeS、CdZnSeS、InP、InGaP、GaN、GaP、ZnSe、ZnTe、ZnTeSe中的至少一种。
  18. 如权利要求15所述的光电器件，其特征在于，所述中间壳层材料选自CdZnSe、ZnSe、CdZnS、CdZnSeS、CdS、CdSeS中的至少一种。
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