WO2020215882A1 - 发光结构、显示面板和显示装置 - Google Patents

发光结构、显示面板和显示装置 Download PDF

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WO2020215882A1
WO2020215882A1 PCT/CN2020/076750 CN2020076750W WO2020215882A1 WO 2020215882 A1 WO2020215882 A1 WO 2020215882A1 CN 2020076750 W CN2020076750 W CN 2020076750W WO 2020215882 A1 WO2020215882 A1 WO 2020215882A1
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light
electron transport
transport layer
layer
emitting
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PCT/CN2020/076750
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English (en)
French (fr)
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李东
梅文海
克里斯塔尔·鲍里斯
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京东方科技集团股份有限公司
北京京东方技术开发有限公司
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Priority to US17/255,569 priority Critical patent/US20210288281A1/en
Priority to EP20795474.4A priority patent/EP3961740A4/en
Priority to JP2020572775A priority patent/JP2022529544A/ja
Publication of WO2020215882A1 publication Critical patent/WO2020215882A1/zh

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    • 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
    • H10K50/16—Electron transporting layers
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/08—Other phosphides
    • C01B25/082—Other phosphides of boron, aluminium, gallium or indium
    • C01B25/087—Other phosphides of boron, aluminium, gallium or indium of gallium or indium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G9/00—Compounds of zinc
    • C01G9/006—Compounds containing, besides zinc, two ore more other elements, with the exception of oxygen or hydrogen
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    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/0883—Arsenides; Nitrides; Phosphides
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    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/70—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing phosphorus
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    • 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]
    • H10K50/11—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
    • 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
    • H10K50/16—Electron transporting layers
    • H10K50/166—Electron transporting layers comprising a multilayered structure
    • 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
    • H10K50/80—Constructional details
    • H10K50/805—Electrodes
    • H10K50/82—Cathodes
    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
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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
    • 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 embodiments of the present disclosure relate to a light emitting structure, a display panel, and a display device.
  • LED Light Emitting Diode
  • Quantum Dot is a new type of luminescent material, which has the advantages of high light color purity, high luminous quantum efficiency, adjustable luminous color, and long service life. It has become the current research hotspot of new LED luminescent materials. Therefore, Quantum Dot Light Emitting Diode (QLED) using quantum dot materials as the light-emitting layer has become the main direction of current research on new display devices.
  • QLED Quantum Dot Light Emitting Diode
  • the embodiments of the present disclosure provide a light emitting structure, a display panel, and a display device.
  • the light emitting structure includes a first light emitting element; the first light emitting element includes a first light emitting layer, a first electron transport layer and a first cathode; the first cathode is arranged in contact with the first electron transport layer, and the conduction band of the first electron transport layer
  • the energy level is greater than the Fermi level of the first cathode, and the difference between the bottom energy level of the conduction band of the first electron transport layer and the Fermi level of the first cathode is in the range of 0.3-0.6 eV.
  • the bottom energy level of the conduction band of the first electron transport layer is greater than the Fermi level of the first cathode, electrons need to cross the barrier from the first cathode to the first electron transport layer, and the first electron transports
  • the difference between the bottom energy level of the conduction band of the layer and the Fermi level of the first cathode is in the range of 0.3-0.6 eV, so that the electron injection efficiency of the first light-emitting element can be appropriately reduced and the hole injection efficiency of the first light-emitting element Matching, thereby improving the luminous efficiency and stability of the first light-emitting element.
  • At least one embodiment of the present disclosure provides a light emitting structure including: a first light emitting element, including a first light emitting layer, a first electron transport layer, and a first cathode, the first cathode being in contact with the first electron transport layer Setting, the conduction band bottom energy level of the first electron transport layer is greater than the Fermi energy level of the first cathode, and the conduction band bottom energy level of the first electron transport layer is greater than the Fermi energy level of the first cathode
  • the range of the difference between the levels is 0.3-0.6 eV.
  • the material of the first light-emitting layer includes a cadmium-free quantum dot material
  • the first electron transport layer includes ZnMgO nanoparticles
  • the Mg The mole percentage is 10%-20%.
  • the material of the first light emitting layer includes indium phosphide.
  • the mole percentage of Mg in the first electron transport layer is 13%-16%.
  • the light-emitting structure provided by an embodiment of the present disclosure further includes: a second light-emitting element including a second light-emitting layer, a second electron transport layer and a second cathode, the second cathode being arranged in contact with the second electron transport layer
  • a second light-emitting element including a second light-emitting layer, a second electron transport layer and a second cathode, the second cathode being arranged in contact with the second electron transport layer
  • the bottom energy level of the conduction band of the first light-emitting layer is smaller than the bottom energy level of the conduction band of the second light-emitting layer, and the bottom energy level of the conduction band of the first electron transport layer is greater than that of the second electron transport layer. With bottom energy level.
  • the potential barrier of electrons from the first cathode to the first electron transport layer is greater than the potential of electrons from the second cathode to the second electron transport layer. base.
  • the bottom energy level of the conduction band of the first light-emitting layer is smaller than the bottom energy level of the conduction band of the first electron transport layer, and the conduction band of the second light-emitting layer
  • the bottom energy level is greater than the conduction band bottom energy level of the second electron transport layer, and the Fermi energy level of the second cathode is approximately equal to the conduction band bottom energy level of the second electron transport layer.
  • the first electron transport layer includes ZnMgO nanoparticles
  • the second electron transport layer includes ZnO nanoparticles or ZnMgO nanoparticles
  • the first electron transport layer The mole percentage of Mg is greater than the mole percentage of Mg in the second electron transport layer.
  • the mole percentage of Mg in the first electron transport layer is 10%-20%, and the mole percentage of Mg in the second electron transport layer is less than 5%.
  • At least one of the first light-emitting layer and the second light-emitting layer is a quantum dot light-emitting layer, and the first cathode and the second cathode are the same conductive layer.
  • the light-emitting structure provided by an embodiment of the present disclosure further includes: a third light-emitting element including a third light-emitting layer, a third electron transport layer, and a third cathode, the third cathode being arranged in contact with the third electron transport layer
  • a third light-emitting element including a third light-emitting layer, a third electron transport layer, and a third cathode, the third cathode being arranged in contact with the third electron transport layer
  • the bottom energy level of the conduction band of the third light-emitting layer is greater than the bottom energy level of the conduction band of the first light-emitting layer and less than the bottom energy level of the conduction band of the second light-emitting layer.
  • the band bottom energy level is smaller than the conduction band bottom energy level of the first electron transport layer, and the conduction band bottom energy level of the third electron transport layer is greater than the conduction band bottom energy level of the second electron transport layer.
  • the potential barrier of electrons from the third cathode to the third electron transport layer is greater than the potential of electrons from the second cathode to the second electron transport layer.
  • the barrier is smaller than the barrier of electrons from the first cathode to the first electron transport layer.
  • the first electron transport layer includes ZnMgO nanoparticles
  • the second electron transport layer includes ZnO nanoparticles or ZnMgO nanoparticles
  • the third electron transport layer includes For ZnMgO nanoparticles, the mole percentage of Mg in the third electron transport layer is less than the mole percentage of Mg in the first electron transport layer and greater than the mole percentage of Mg in the second electron transport layer.
  • the mole percentage of Mg in the first electron transport layer is 10%-20%, and the mole percentage of Mg in the second electron transport layer is less than 5%.
  • the mole percentage of Mg in the third electron transport layer is 5%-10%.
  • the electron mobility of the first electron transport layer is lower than the electron mobility of the second electron transport layer.
  • the electron mobility of the third electron transport layer is greater than the electron mobility of the second electron transport layer and is less than the electron mobility of the second electron transport layer. rate.
  • the first light emitting layer is configured to emit red light
  • the second light emitting layer is configured to emit blue light
  • the first light-emitting layer is configured to emit red light
  • the second light-emitting layer is configured to emit blue light
  • the third light-emitting layer is configured to emit green light. Light.
  • At least one embodiment of the present disclosure further provides a display panel including a plurality of light-emitting structures arranged in an array, and each of the light-emitting structures is the aforementioned light-emitting structure.
  • At least one embodiment of the present disclosure also provides a display device including the above-mentioned display panel.
  • FIG. 1 is a schematic structural diagram of a light-emitting structure according to an embodiment of the present disclosure
  • FIG. 2 is a comparison diagram of electron injection efficiency and hole injection efficiency of a first light-emitting element with a light-emitting structure using different electron transport layers according to an embodiment of the present disclosure
  • FIG. 3 is a comparison diagram of current efficiencies of a first light-emitting element with a light-emitting structure using different electron transport layers according to an embodiment of the present disclosure
  • FIG. 4 is a schematic diagram of the energy levels of different light-emitting layers and different electron transport layers in a light-emitting structure according to an embodiment of the present disclosure.
  • FIG. 5 is a schematic diagram of energy levels of different light-emitting layers and different electron transport layers in another light-emitting structure according to an embodiment of the present disclosure.
  • the electron injection efficiency of the red and green quantum dot light-emitting layer is generally better than the hole injection efficiency, resulting in the red and green quantum dot light-emitting layer of the carrier
  • the number of electrons is greater than the number of holes; on the contrary, the electron injection efficiency of the blue quantum dot light-emitting layer is weaker than the hole injection efficiency, resulting in that the number of holes in the carriers of the blue quantum dot light-emitting layer is greater than the number of electrons.
  • the electron and hole imbalance of the quantum dot light-emitting layer in the QLED device, and the electron-hole imbalance will not only reduce the ability of the injected charge to be converted into excitons, but also cause the charge to accumulate in the QLED device , Increasing the non-radiative transition of the charged excitons, reducing the efficiency and attenuating the service life, thus becoming a bottleneck limiting the further improvement of the efficiency and stability of the QLED device.
  • inventions of the present disclosure provide a light emitting structure, a display panel, and a display device.
  • the light emitting structure includes a first light emitting element; the first light emitting element includes a first light emitting layer, a first electron transport layer and a first cathode; the first cathode is arranged in contact with the first electron transport layer, and the conduction band of the first electron transport layer
  • the energy level is greater than the Fermi level of the first cathode, and the difference between the bottom energy level of the conduction band of the first electron transport layer and the Fermi level of the first cathode is in the range of 0.3-0.6 eV.
  • the bottom energy level of the conduction band of the first electron transport layer is greater than the Fermi level of the first cathode, electrons need to cross the barrier from the first cathode to the first electron transport layer, and the first electron transports
  • the difference between the bottom energy level of the conduction band of the layer and the Fermi level of the first cathode is in the range of 0.3-0.6 eV, so that the electron injection efficiency of the first light-emitting element can be appropriately reduced and the hole injection efficiency of the first light-emitting element Matching, thereby improving the luminous efficiency and stability of the first light-emitting element.
  • FIG. 1 is a schematic structural diagram of a light emitting structure provided according to an embodiment of the present disclosure.
  • the light emitting structure 100 includes a first light emitting element 110; the first light emitting element 110 includes a first light emitting layer 111, a first electron transport layer 112 and a first cathode 113; the first cathode 113 and the first electron transport The layer 112 is arranged in contact.
  • the first cathode 113 is used to provide electrons.
  • the bottom energy level of the conduction band of the first electron transport layer 112 is greater than the Fermi level of the first cathode 113, and the difference between the bottom energy level of the conduction band of the first electron transport layer 112 and the Fermi level of the first cathode 113 is in the range 0.3-0.6eV.
  • contact arrangement refers to the case of direct contact, and no other film structure is provided between the first cathode and the first electron transport layer.
  • the electron injection efficiency of the first light-emitting layer is better than the hole injection efficiency
  • the bottom energy level of the conduction band of the first electron transport layer is greater than the Fermi level of the first cathode
  • electrons need to cross the barrier from the first cathode to the first electron transport layer, and the difference between the bottom energy level of the conduction band of the first electron transport layer and the Fermi level of the first cathode is in the range of 0.3-0.6 eV, so that The electron injection efficiency of the first light-emitting element is appropriately reduced and matched with the hole injection efficiency of the first light-emitting element, thereby improving the luminous efficiency and stability of the first light-emitting element.
  • the first light-emitting layer 111 and the first electron transport layer 112 are arranged in contact, that is, the first light-emitting element 110 is not provided with an electron injection layer, thereby reducing the first light emission.
  • the electron injection efficiency of the element 110 reduces the thickness of the first light-emitting element 110 at the same time, thereby providing a thin and light light-emitting structure.
  • the first light-emitting layer 111 may be a red quantum dot light-emitting layer. Since the electron injection efficiency of the usual red quantum dot light-emitting layer is generally better than the hole injection efficiency, the holes and electrons in the carriers of the red quantum dot light-emitting layer are very unbalanced; and the light-emitting structure provided by the embodiment of the present disclosure is Choose a suitable material so that the bottom energy level of the conduction band of the first electron transport layer is greater than the Fermi level of the first cathode, and the difference between the bottom energy level of the conduction band of the first electron transport layer and the Fermi level of the first cathode The range is 0.3-0.6 eV, so that the electron injection efficiency and hole injection efficiency of the first light-emitting element match, thereby improving the luminous efficiency and stability of the first light-emitting element.
  • the material of the first light-emitting layer 111 may include a cadmium-free quantum dot material, thereby reducing environmental pollution.
  • the first electron transport layer 112 includes ZnMgO nanoparticles, that is, Mg-doped ZnO nanoparticles, and the mole percentage of Mg in the first electron transport layer 112 is 10%-20%, so that the conductivity of the first electron transport layer 112
  • the difference between the bottomed energy level and the Fermi energy level of the first cathode 113 is in the range of 0.3-0.6 eV.
  • the material of the first cathode 113 may be silver or aluminum. Therefore, the Fermi level of the first cathode 113 may be in the range of -4.3 to -4.2 eV.
  • the material of the first light-emitting layer 111 may include indium phosphide (InP), and the mole percentage of Mg in the first electron transport layer 112 is 13%-16%.
  • the bottom energy level of the conduction band of the first electron transport layer 112 is approximately -3.83 eV, and the Fermi energy level of the first cathode 113 may range from -4.3 to
  • the difference between the bottom energy level of the conduction band of the first electron transport layer 112 and the Fermi energy level of the first cathode 113 is approximately 0.37-0.47 eV.
  • the luminous efficiency and stability of the first light-emitting element 110 may be greatly increased.
  • FIGS. 2 and 3 are comparison diagrams of electron injection efficiency and hole injection efficiency of a first light-emitting element with a light-emitting structure provided according to an embodiment of the present disclosure using different electron transport layers;
  • FIG. 3 is a comparison diagram provided according to an embodiment of the present disclosure A comparison chart of current efficiency of different electron transport layers used in the first light-emitting element of this light-emitting structure.
  • the first light-emitting element in FIGS. 2 and 3 is a red quantum dot light-emitting element, and the first light-emitting layer is made of indium phosphide (InP).
  • InP indium phosphide
  • curve 1 is the hole injection efficiency of the first light-emitting element
  • curve 2 is the electron injection efficiency of the first light-emitting element using ZnMgO nanoparticles with 15% Mg in the electron transport layer
  • curve 3 The electron injection efficiency of the first light-emitting element using ZnMgO nanoparticles with 5% mole percentage of Mg in the electron transport layer
  • curve 4 shows that the electron transport layer uses ZnMgO nanoparticles or ZnMgO nanoparticles with 0% mole percentage of Mg, that is, ZnO The electron injection efficiency of the first light-emitting element of the nanoparticle.
  • the electron injection efficiency shown in curve 2 is more matched with the hole injection efficiency shown in curve 1, which is beneficial to improving the luminous efficiency and stability of the first light-emitting element.
  • the hole injection efficiency of curve 1 is the curve measured when the first light-emitting element only includes the light-emitting layer and the hole transport layer;
  • the electron injection efficiency of curve 2 is the first light-emitting element only includes the light-emitting layer and electrons The curve measured by the transport layer;
  • the electron injection efficiency of curve 3 is the curve measured when the first light-emitting element only includes the light-emitting layer and the electron transport layer;
  • the electron injection efficiency of curve 4 is the first light-emitting element only includes the light-emitting layer and electrons The measured curve of the transmission layer.
  • curve 5 is the current efficiency of the first light-emitting element with 15% Mg ZnMgO nanoparticles in the electron transport layer
  • curve 6 is the electron transport layer ZnMgO nano particles with 5% Mg mole percentage The current efficiency of the first light-emitting element of the particle
  • curve 7 is the current efficiency of the first light-emitting element with ZnO nanoparticles or 0% ZnMgO nanoparticles with a molar percentage of Mg as the electron transport layer.
  • the first light-emitting element 110 further includes a first hole transport layer 114, a first hole injection layer 115 and a first anode 116.
  • the first hole transport layer 114 is provided on the side of the first light-emitting layer 111 away from the first electron transport layer 112, and the first hole injection layer 115 is provided on the side of the first hole transport layer 114 away from the first light-emitting layer 111
  • the first anode 116 is disposed on the side of the first hole injection layer 115 away from the first hole transport layer 114.
  • the first anode 116 may be a transparent conductive oxide or a conductive polymer, and the transparent conductive oxide may be indium tin oxide (ITO), FTO (SnO 2 ), or the like.
  • the materials of the first hole transport layer 114 and the first hole injection layer 115 can be selected according to actual conditions, and the embodiments of the present disclosure are not limited herein.
  • the light-emitting structure further includes a base substrate 101 for carrying the aforementioned first light-emitting element 110.
  • the base substrate 101 may be a transparent substrate, such as a glass substrate, a quartz substrate, a plastic substrate, or the like.
  • the base substrate 101 may also be a flexible transparent substrate, for example, a polyethylene terephthalate (PET) substrate.
  • PET polyethylene terephthalate
  • the light emitting structure 100 further includes a second light emitting element 120; the first light emitting element 110 and the second light emitting element 120 can be used to emit light of different colors.
  • the second light-emitting element 120 includes a second light-emitting layer 121, a second electron transport layer 122 and a second cathode 123.
  • the second cathode 123 is arranged in contact with the second electron transport layer 122, the conduction band bottom energy level of the first light emitting layer 111 is smaller than the conduction band bottom energy level of the second light emitting layer 121, and the conduction band bottom energy level of the first electron transport layer 112 It is greater than the bottom energy level of the conduction band of the second electron transport layer 122.
  • different light-emitting elements use electron transport layers made of different materials. Since the bottom energy level of the conduction band of the first light-emitting layer 111 is smaller than that of the second light-emitting layer 121, the difficulty for electrons from the first electron transport layer 112 to the first light-emitting layer 111 is less than that of the electrons from the second electron transport layer 122 It is difficult to reach the second light-emitting layer 121.
  • the potential barrier of electrons from the first cathode 113 to the first transport layer 112 is greater than the barrier of electrons from the second cathode 123 to the second electron transport layer 122, thereby reducing the electron injection to a certain extent.
  • the efficiency of the first light-emitting layer 111 is thus balanced with the hole injection efficiency in the first light-emitting layer 111; and, because the bottom energy level of the conduction band of the first electron transport layer 112 is greater than that of the second electron transport layer 122
  • the light-emitting structure provided in this example can also reduce the barrier of electrons from the second cathode 123 to the second electron transport layer 122, and improve the efficiency of electron injection into the second light-emitting layer 121 to a certain extent.
  • the hole injection efficiency in the layer 121 is balanced, thereby simultaneously improving the luminous efficiency and stability of the first light-emitting element 110 and the second light-emitting element 120.
  • the first cathode 113 and the second cathode 123 are the same conductive layer, that is, the first light-emitting element 110 and the second light-emitting element 120 share a cathode layer.
  • the potential barrier of electrons from the first cathode 113 to the first electron transport layer 112 is greater than the potential barrier of electrons from the second cathode 123 to the second electron transport layer 122.
  • FIG. 4 is a schematic diagram of the energy levels of different light-emitting layers and different electron transport layers in a light-emitting structure according to an embodiment of the present disclosure.
  • the conduction band bottom energy level of the first light-emitting layer 111 is smaller than that of the first electron transport layer 112, and the conduction band bottom energy level of the second light-emitting layer 121 is greater than that of the second electron transport layer 122.
  • the bottom energy level of the conduction band that is, there is no or almost no potential barrier for electrons from the first electron transport layer 112 to the first light-emitting layer 111, while the electrons need to cross from the second electron transport layer 122 to the second light-emitting layer 121 Barrier.
  • the Fermi level of the second cathode 123 is approximately equal to the bottom energy level of the conduction band of the second electron transport layer 122, that is, there is no or almost no electrons from the second cathode 123 to the second electron transport layer 122.
  • the light-emitting structure can improve the electron injection efficiency of electrons from the second cathode 123 to the second light-emitting layer 121 to a certain extent, so as to balance with the hole injection efficiency in the second light-emitting layer 121, thereby improving the second light emission.
  • the luminous efficiency and stability of the element 120 can improve the electron injection efficiency of electrons from the second cathode 123 to the second light-emitting layer 121 to a certain extent, so as to balance with the hole injection efficiency in the second light-emitting layer 121, thereby improving the second light emission.
  • the above-mentioned Fermi level of the second cathode is approximately equal to the bottom energy level of the conduction band of the second electron transport layer, which means that the Fermi level of the second cathode is equal to the bottom energy of the conduction band of the second electron transport layer.
  • the ratio of the difference between the levels to the absolute value of the Fermi level of the second cathode is within 4%.
  • the first electron transport layer 112 includes ZnMgO nanoparticles
  • the second electron transport layer 122 includes ZnO nanoparticles or ZnMgO nanoparticles
  • the mole percentage of Mg in the first electron transport layer 112 is greater than that of the second electron transport layer.
  • the mole percentage of Mg in 122 is greater than that of the second electron transport layer.
  • the mole percentage of Mg in the first electron transport layer 112 is 10%-20%, and the mole percentage of Mg in the second electron transport layer 122 is less than 5%. It should be noted that when the second electron transport layer 122 is ZnO nanoparticles, it can be considered that the second electron transport layer 122 is ZnMgO nanoparticles with 0 mole percentage of Mg.
  • Table 1 is an energy level data table of an electron transport layer provided according to an embodiment of the present disclosure.
  • the first electron transport layer 112 is ZnMgO nanoparticles with a Mg mole percentage of 15%
  • the second electron transport layer 122 is ZnMgO nanoparticles with a Mg mole percentage of 0%. It can be seen that the bottom energy level of the conduction band of the first electron transport layer 112 is greater than the bottom energy level of the conduction band of the second electron transport layer 122.
  • the difference between the bottom energy level of the conduction band of the first electron transport layer 112 and the Fermi level of the first cathode 113 is approximately It is 0.37-0.47 eV, and the difference between the bottom energy level of the conduction band of the second electron transport layer 122 and the Fermi energy level of the second cathode 123 is less than 0.1 eV.
  • the light-emitting structure can reduce the efficiency of electron injection into the first light-emitting layer 111 to a certain extent, so as to balance with the hole injection efficiency in the first light-emitting layer 111; and to a certain extent, improve the electron injection into the second light-emitting layer 111.
  • the efficiency of the light-emitting layer 121 is thus balanced with the hole injection efficiency in the second light-emitting layer 121.
  • the electron mobility of the first electron transport layer 112 is less than the electron mobility of the second electron transport layer 122, thereby also reducing the efficiency of electron injection into the first light-emitting layer 111 to a certain extent, thereby reducing
  • the hole injection efficiency in a light-emitting layer 111 is balanced; and the efficiency of electron injection into the second light-emitting layer 121 is improved to a certain extent, so as to be balanced with the hole injection efficiency in the second light-emitting layer 121.
  • the electrons of the first electron transport layer 112 is ZnMgO nanoparticles with 15% Mg mole percentage
  • the second electron transport layer 122 is ZnMgO nanoparticles with 0% Mg mole percentage
  • the electrons of the first electron transport layer 112 The mobility is less than the electron mobility of the second electron transport layer 122.
  • the first light-emitting layer and the second light-emitting layer is a quantum dot light-emitting layer.
  • the first light-emitting layer can be a red quantum dot light-emitting layer
  • the second light-emitting layer can be a blue quantum dot light-emitting layer
  • the first light-emitting layer can be a red cadmium-free quantum dot light-emitting material, such as indium phosphide (InP),
  • the second light-emitting layer can be a blue quantum dot luminescent material, for example, cadmium selenide (CdSe), such as CdSe/ZnS core-shell quantum dot material.
  • CdSe cadmium selenide
  • the second light-emitting element 120 further includes a second hole transport layer 124, a second hole injection layer 125 and a second anode 116.
  • the second hole transport layer 124 is disposed on the side of the second light emitting layer 121 away from the second electron transport layer 122
  • the second hole injection layer 125 is disposed on the side of the second hole transport layer 124 away from the second light emitting layer 121
  • the second anode 126 is disposed on the side of the second hole injection layer 125 away from the second hole transport layer 124.
  • the second anode 126 may be a transparent conductive oxide or a conductive polymer, and the transparent conductive oxide may be indium tin oxide (ITO), FTO (SnO2), or the like.
  • ITO indium tin oxide
  • FTO FTO
  • the materials of the second hole transport layer 124 and the second hole injection layer 125 can be selected according to actual conditions, and the embodiments of the present disclosure are not limited herein.
  • the first light-emitting element 110 and the second light-emitting element 120 are disposed on the base substrate 101 in the same layer. That is, the first anode 116 of the first light-emitting element 110 and the second anode 126 of the second light-emitting element 120 can be arranged in the same layer; the first hole injection layer 115 of the first light-emitting element 110 and the second light-emitting element 120 The second hole injection layer 125 may be provided in the same layer; the first hole transport layer 114 of the first light-emitting element 110 and the second hole transport layer 124 of the second light-emitting element 120 may be provided in the same layer; The first light-emitting layer 111 and the second light-emitting layer 121 of the second light-emitting element 120 can be provided in the same layer; the first electron transport layer 112 of the first light-emitting element 110 and the second electron transport layer 122 of the second light-emitting element 120 can be the same
  • first anode 116 and the second anode 126 can be made of the same material
  • first anode 116 and the second anode 126 can be formed by patterning the same conductive layer.
  • the base substrate 101 may be a transparent substrate, such as a glass substrate, a quartz substrate, a plastic substrate, or the like.
  • the base substrate 101 may also be a flexible transparent substrate, for example, a polyethylene terephthalate (PET) substrate.
  • PET polyethylene terephthalate
  • the light-emitting structure 100 further includes a third light-emitting element 130; the third light-emitting element 130 includes a third light-emitting layer 131, a third electron transport layer 132 and a third cathode 133.
  • the third cathode 133 is arranged in contact with the third electron transport layer 132, and the bottom energy level of the conduction band of the third light-emitting layer 131 is greater than the bottom energy level of the conduction band of the first light-emitting layer 111 and smaller than that of the second light-emitting layer 121 ,
  • the conduction band bottom energy level of the third electron transport layer 132 is smaller than the conduction band bottom energy level of the first electron transport layer 112, and the conduction band bottom energy level of the third electron transport layer 132 is greater than that of the second electron transport layer 122 energy level.
  • different light-emitting elements adopt electron transport layers of different materials. Since the conduction band bottom energy level of the third light-emitting layer 131 is greater than the conduction band bottom energy level of the first light-emitting layer 111 and smaller than the conduction band bottom energy level of the second light-emitting layer 121, that is, the conduction band bottom energy level of the third light-emitting layer 131 Between the first light-emitting layer 111 and the second light-emitting layer 121, the difficulty of electrons from the third electron transport layer 132 to the third light-emitting layer 131 is also between that of electrons from the first electron transport layer 112 to the first light-emitting layer 111.
  • the potential barrier of layer 132 is smaller than the potential barrier of electrons from the first cathode 113 to the first electron transport layer 112, and is greater than the potential barrier of electrons from the second cathode 123 to the second electron transport layer 122, thereby reducing the electrons to a certain extent.
  • the efficiency of injection into the third light-emitting layer 131 is balanced with the hole injection efficiency in the third light-emitting layer 131, thereby simultaneously improving the luminous efficiency and the efficiency of the first light-emitting element 110, the second light-emitting element 120, and the third light-emitting element 130. stability.
  • the first cathode 113, the second cathode 123, and the third cathode 133 are the same conductive layer, that is, the first light-emitting element 110, the second light-emitting element 120, and the third light-emitting element 130 share a cathode layer.
  • the barrier of electrons from the third cathode 133 to the third electron transport layer 132 is greater than the barrier of electrons from the second cathode 123 to the second electron transport layer 122, and is smaller than the barrier of electrons from the first cathode 113 to the first electron transport layer 112. Barrier.
  • FIG. 5 is a schematic diagram of energy levels of different light-emitting layers and different electron transport layers in another light-emitting structure according to an embodiment of the present disclosure.
  • the conduction band bottom energy level of the first light-emitting layer 111 is smaller than that of the first electron transport layer 112
  • the conduction band bottom energy level of the second light-emitting layer 121 is greater than that of the second electron transport layer 122.
  • the conduction band bottom energy level of the third light-emitting layer 131 is slightly larger than that of the third electron transport layer 132.
  • the light-emitting structure can greatly improve the electron injection efficiency of electrons from the first cathode 113 to the first light-emitting layer 111, and reduce the electron injection efficiency of electrons from the third cathode 133 to the third light-emitting layer 131 to a small extent, and Improve the electron injection efficiency from the second cathode 123 to the second light-emitting layer 121, so as to balance the hole-electron injection efficiency in the first light-emitting layer 111, the second light-emitting layer 121, and the third light-emitting layer 131 at the same time, thereby Improve the luminous efficiency and stability of the light-emitting structure.
  • the first electron transport layer 112 includes ZnMgO nanoparticles
  • the second electron transport layer 122 includes ZnO nanoparticles or ZnMgO nanoparticles
  • the third electron transport layer 132 includes ZnMgO nanoparticles
  • the third electron transport layer 132 The mole percentage of Mg in the first electron transport layer 112 is less than the mole percentage of Mg in the first electron transport layer 112 and greater than the mole percentage of Mg in the second electron transport layer 122.
  • the mole percentage of Mg in the first electron transport layer 112 is 10%-20%
  • the mole percentage of Mg in the second electron transport layer 122 is less than 5%
  • the mole percentage of Mg in the third electron transport layer 132 The percentage is 5%-10%. It should be noted that when the second electron transport layer 122 is ZnO nanoparticles, it can be considered that the second electron transport layer 122 is ZnMgO nanoparticles with 0 mole percentage of Mg.
  • Table 2 is an energy level data table of another electron transport layer provided according to an embodiment of the present disclosure.
  • the first electron transport layer 112 is ZnMgO nanoparticles with a molar percentage of Mg of 15%
  • the second electron transport layer 122 is ZnMgO nanoparticles with a molar percentage of Mg of 0%
  • the third electron transport layer 132 is The molar percentage of Mg is 5% of ZnMgO nanoparticles. It can be seen that the bottom energy level of the conduction band of the first electron transport layer 112 is greater than that of the third electron transport layer 132, and the bottom energy level of the conduction band of the third electron transport layer 132 is greater than that of the second electron transport layer 122 Bottom energy level.
  • the bottom energy level of the conduction band of the first electron transport layer 112 and the Fermi level of the first cathode 113 range from -4.3 to -4.2 eV
  • the bottom energy level of the conduction band of the first electron transport layer 112 and the Fermi level of the first cathode 113 The difference in energy level is approximately 0.37-0.47 eV
  • the difference between the bottom energy level of the conduction band of the second electron transport layer 122 and the Fermi level of the second cathode 123 is less than 0.1 eV
  • the bottom energy of the conduction band of the third electron transport layer 132 The difference between the Fermi level of the third cathode 133 and the third cathode 133 is less than 0.2 eV.
  • the light-emitting structure can reduce the efficiency of electron injection into the first light-emitting layer 111 to a certain extent, so as to balance with the hole injection efficiency in the first light-emitting layer 111, and improve the electron injection into the second light-emitting layer to a certain extent.
  • the efficiency of the layer 121 is thus balanced with the hole injection efficiency in the second light-emitting layer 121, and the efficiency of electron injection into the third light-emitting layer 131 is reduced to a certain extent, which is compared with the hole injection efficiency in the third light-emitting layer 131. The efficiency is balanced.
  • the electron mobility of the third electron transport layer 132 is greater than the electron mobility of the second electron transport layer 122 and is less than the electron mobility of the second electron transport layer 112. Therefore, the light-emitting structure can further greatly improve the electron injection efficiency from the first cathode 113 to the first light-emitting layer 111, and reduce the electrons from the third cathode 133 to the third light-emitting layer 131.
  • Injection efficiency and improve the electron injection efficiency from the second cathode 123 to the second light-emitting layer 121, thereby simultaneously increasing the hole-electron injection efficiency in the first light-emitting layer 111, the second light-emitting layer 121, and the third light-emitting layer 131 A balance is achieved, thereby improving the luminous efficiency and stability of the light-emitting structure.
  • the first electron transport layer 112 is made of ZnMgO nanoparticles with a molar percentage of Mg of 15%
  • the second electron transport layer 122 is made of ZnMgO nanoparticles with a molar percentage of Mg of 0%
  • the third electron transport layer 132 is made of Mg.
  • the electron mobility of the third electron transport layer 132 is greater than the electron mobility of the second electron transport layer 122 and is less than the electron mobility of the second electron transport layer 112.
  • the first light-emitting layer may be a red quantum dot light-emitting layer
  • the second light-emitting layer may be a blue quantum dot light-emitting layer
  • the third light-emitting layer may be a green quantum dot light-emitting layer
  • the first light-emitting layer may be red Cadmium-free quantum dot light-emitting materials, for example, indium phosphide (InP), such as InP/ZnS core-shell quantum dot materials
  • the second light-emitting layer can use blue quantum dot light-emitting materials, for example, cadmium selenide (CdSe), such as CdSe /ZnS core-shell quantum dot material
  • the third light-emitting layer can be a green cadmium-free quantum dot light-emitting material, for example, indium phosphide (InP), such as InP/ZnS core-shell quantum dot material.
  • the third light-emitting element 130 further includes a third hole transport layer 134, a third hole injection layer 135 and a third anode 136.
  • the third hole transport layer 134 is disposed on the side of the third light-emitting layer 131 away from the third electron transport layer 132
  • the third hole injection layer 135 is disposed on the side of the third hole transport layer 134 away from the third light-emitting layer 131
  • the third anode 136 is disposed on the side of the third hole injection layer 135 away from the third hole transport layer 134.
  • the third anode 136 may be a transparent conductive oxide or a conductive polymer, and the transparent conductive oxide may be indium tin oxide (ITO), FTO (SnO2), or the like.
  • ITO indium tin oxide
  • FTO FTO
  • the materials of the third hole transport layer 134 and the third hole injection layer 135 can be selected according to actual conditions, and the embodiments of the present disclosure are not limited herein.
  • the first light emitting element 110, the second light emitting element 120 and the third light emitting element 130 may be provided on the base substrate 101 in the same layer. That is, the first anode 116 of the first light-emitting element 110, the second anode 126 of the second light-emitting element 120, and the third anode 136 of the third light-emitting element 130 can be arranged in the same layer; The hole injection layer 115, the second hole injection layer 125 of the second light emitting element 120, and the third hole injection layer 135 of the third light emitting element 130 may be provided in the same layer; the first hole transport layer 114 of the first light emitting element 110 The second hole transport layer 124 of the second light emitting element 120 and the third hole transport layer 134 of the third light emitting element 130 can be arranged in the same layer; the first light emitting layer 111 and the second light emitting element 120 of the first light emitting element 110 The second light-emitting layer 121 of the third light
  • first hole injection layer 115, the second hole injection layer 125, and the third hole injection layer 135 can have different thicknesses according to actual conditions; the first hole transport layer 114, the second hole transport layer The layer 124 and the third hole transport layer 134 can have different thicknesses according to actual conditions.
  • first anode 116, the second anode 126 and the third anode 127 can be made of the same material
  • the first anode 116, the second anode 126 and the third anode 137 can be formed by patterning the same conductive layer.
  • the base substrate 101 may be a transparent substrate, such as a glass substrate, a quartz substrate, a plastic substrate, or the like.
  • the base substrate 101 may also be a flexible transparent substrate, for example, a polyethylene terephthalate (PET) substrate.
  • PET polyethylene terephthalate
  • the light-emitting structure 100 further includes between different light-emitting elements (for example, between the first light-emitting element 110 and the second light-emitting element 120, and between the second light-emitting element 120 and the third light-emitting element 130).
  • the pixel defining layer 180 between the third light-emitting element 130 and the first light-emitting element 110).
  • At least one embodiment of the present disclosure provides a method for manufacturing a light emitting structure.
  • the production method includes the following steps S201-S205.
  • Step S201 forming a first anode, a second anode and a third anode on a base substrate.
  • a deposition method may be used to form an anode layer on a base substrate, and then the anode layer may be patterned to form a first anode, a second anode, and a third anode;
  • the base substrate may be a transparent substrate, such as a glass substrate, a quartz substrate, and a plastic Substrate, etc.;
  • the anode layer can be a transparent conductive oxide or a conductive polymer, and the transparent conductive oxide can be indium tin oxide (ITO), FTO (SnO 2 ), etc.
  • Step S202 forming a first hole injection layer, a second hole injection layer and a third hole injection layer on the side of the first anode, the second anode and the third anode away from the base substrate, respectively.
  • inkjet printing or nanoimprinting can be used to form the first hole injection layer, the second hole injection layer, and the third anode on the side of the first anode, the second anode, and the third anode away from the base substrate, respectively.
  • Hole injection layer The material of the first hole injection layer, the second hole injection layer and the third hole injection layer may be an organic hole injection material, for example: PEDOT: PSS (poly(3,4-ethylenedioxythiophene)-polyphenylene) Ethylene sulfonic acid), or inorganic oxides such as molybdenum oxide (MoOx).
  • PEDOT PEDOT: PSS (poly(3,4-ethylenedioxythiophene)-polyphenylene) Ethylene sulfonic acid), or inorganic oxides such as molybdenum oxide (MoOx).
  • Step S203 forming a first hole transport layer, a second hole transport layer and a third hole on the first hole injection layer, the second hole injection layer and the third hole injection layer far away from the base substrate. Hole transport layer.
  • the first hole transport layer, the second hole transport layer, and the third hole transport layer may be organic hole transport materials, for example, PVK (polyvinylcarbazole), TFB (poly(9,9-dioctyl) Fluorene-CO-N-(4-butylphenyl)diphenylamine)) and TPD(N,N'-diphenyl-N,N'-bis(3-methyllphenyl)-(1,1'-biphenyl)- 4,4'-diamine) and its derivatives, or inorganic hole transport materials, such as nickel oxide (NiOx) and vanadium oxide (VOx).
  • PVK polyvinylcarbazole
  • TFB poly(9,9-dioctyl) Fluorene-CO-N-(4-butylphenyl)diphenylamine)
  • TPD T,N'-diphenyl-N,N'-bis(3-methyllphenyl)-(1,
  • Step S204 forming a first light-emitting layer, a second light-emitting layer and a third light-emitting layer on the side of the first hole transport layer, the second hole transport layer and the third hole transport layer away from the base substrate, respectively.
  • Step S205 forming a first electron transport layer, a second electron transport layer and a third electron transport layer on the side of the first light emitting layer, the second light emitting layer and the third light emitting layer away from the base substrate, respectively.
  • the first electron transport layer is ZnMgO nanoparticles with a molar percentage of Mg of 10%-20%
  • the second electron transport layer is ZnMgO nanoparticles with a molar percentage of Mg less than 5%
  • the third electron transport layer is a mole of Mg. The percentage is 5%-10% of ZnMgO nanoparticles.
  • Step S206 forming a cathode layer on the side of the first electron transport layer, the second electron transport layer and the third electron transport layer away from the base substrate.
  • the cathode layer can be formed on the side of the first electron transport layer, the second electron transport layer, and the third electron transport layer away from the base substrate by evaporation; the material of the cathode layer can be aluminum or silver; The thickness can range from 100-150 nanometers.
  • At least one embodiment of the present disclosure also provides a display panel.
  • the display panel includes a plurality of light-emitting structures 100 arranged in an array, and the light-emitting structures are the light-emitting structures provided in the foregoing embodiments. Therefore, the display panel can appropriately reduce the electron injection efficiency of the first light-emitting element and match the hole injection efficiency of the first light-emitting element, thereby improving the luminous efficiency and stability of the first light-emitting element.
  • the display panel adopts the light-emitting structure in which different light-emitting elements adopt different electron transport layers in the above-mentioned embodiment
  • the display panel can simultaneously improve the luminous efficiency and stability of the first light-emitting element, the second light-emitting element, and the third light-emitting element.
  • the specific description of the embodiment of the light emitting structure please refer to the specific description of the embodiment of the light emitting structure.
  • At least one embodiment of the present disclosure further provides a display device, including the display panel provided in the foregoing embodiment. Therefore, the display panel can appropriately reduce the electron injection efficiency of the first light-emitting element and match the hole injection efficiency of the first light-emitting element, thereby improving the luminous efficiency and stability of the first light-emitting element. Moreover, when the display panel adopts the light-emitting structure in which different light-emitting elements adopt different electron transport layers in the above-mentioned embodiment, the display panel can simultaneously improve the luminous efficiency and stability of the first light-emitting element, the second light-emitting element, and the third light-emitting element. For details, please refer to the specific description of the embodiment of the light emitting structure.
  • the display device may be any product or component with a display function, such as a smart phone, a tablet computer, a television, a monitor, a notebook computer, a digital photo frame, a navigator, and the like.
  • a display function such as a smart phone, a tablet computer, a television, a monitor, a notebook computer, a digital photo frame, a navigator, and the like.

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Abstract

一种发光结构、显示面板和显示装置。该发光结构(100)包括第一发光元件(110)；第一发光元件(110)包括第一发光层(111)、第一电子传输层(112)和第一阴极(113)；第一阴极(113)与第一电子传输层(112)接触设置，第一电子传输层(112)的导带底能级大于第一阴极(113)的费米能级，第一电子传输层(112)的导带底能级与第一阴极(113)的费米能级之差的范围在0.3-0.6eV。

Description

发光结构、显示面板和显示装置
本申请要求于2019年04月26日递交的中国专利申请第201910343913.6号的优先权，在此全文引用上述中国专利申请公开的内容以作为本申请的一部分。
技术领域
本公开的实施例涉及一种发光结构、显示面板和显示装置。
背景技术
随着显示技术的不断发展，显示装置的种类也越来越多。发光二极管(Light Emitting Diode，LED)显示装置由于其具有自发光、亮度高、工作电压低、功耗小、寿命长、耐冲击和性能稳定等优点受到业界广泛的关注。并且，由于发光二极管显示装置不需要额外设置背光模组，具有较轻的重量，从而利于显示装置的轻薄化，因此具有较好的市场前景。
量子点(Quantum Dot，QD)是一种新型的发光材料，具有光色纯度高、发光量子效率高、发光颜色可调、使用寿命长等优点，成为目前新型的LED发光材料的研究热点。因此，以量子点材料作为发光层的量子点发光二极管(Quantum Dot Light Emitting Diode，QLED)成为了目前新型显示器件研究的主要方向。
发明内容
本公开实施例提供一种发光结构、显示面板和显示装置。该发光结构包括第一发光元件；第一发光元件包括第一发光层、第一电子传输层和第一阴极；第一阴极与第一电子传输层接触设置，第一电子传输层的导带底能级大于第一阴极的费米能级，第一电子传输层的导带底能级与第一阴极的费米能级之差的范围在0.3-0.6eV。在该发光结构中，由于第一电子传输层的导带底能级大于第一阴极的费米能级，因此电子从第一阴极到第一电子传输层需要跨越势垒，并且第一电子传输层的导带底能级与第一阴极的费米能级之差的范围在0.3-0.6eV，从而可适当地降低第一发光元件的电子注入效率并与第一发光元件的空穴注入效率相匹配，进而提高第一发光元件的发光效率和稳定性。
本公开至少一个实施例提供一种发光结构，其包括：第一发光元件，包括第一发光层、第一电子传输层和第一阴极，所述第一阴极与所述第一电子传输层接触设置，所述第一电子传输层的导带底能级大于所述第一阴极的费米能级，所述第一电子传输层的导带底能级与所述第一阴极的费米能级之差的范围在0.3-0.6eV。
例如，在本公开一实施例提供的发光结构中，所述第一发光层的材料包括无镉量子点材料，所述第一电子传输层包括ZnMgO纳米粒子，所述第一电子传输层中Mg的摩尔百分比为10％-20％。
例如，在本公开一实施例提供的发光结构中，所述第一发光层的材料包括磷化铟。
例如，在本公开一实施例提供的发光结构中，所述第一电子传输层中Mg的摩尔百分比为13％-16％。
例如，本公开一实施例提供的发光结构还包括：第二发光元件，包括第二发光层、第二电子传输层和第二阴极，所述第二阴极与所述第二电子传输层接触设置，所述第一发光层的导带底能级小于所述第二发光层的导带底能级，所述第一电子传输层的导带底能级大于所述第二电子传输层的导带底能级。
例如，在本公开一实施例提供的发光结构中，电子从所述第一阴极到所述第一电子传输层的势垒大于电子从所述第二阴极到所述第二电子传输层的势垒。
例如，在本公开一实施例提供的发光结构中，所述第一发光层的导带底能级小于所述第一电子传输层的导带底能级，所述第二发光层的导带底能级大于所述第二电子传输层的导带底能级，所述第二阴极的费米能级与所述第二电子传输层的导带底能级大致相等。
例如，在本公开一实施例提供的发光结构中，所述第一电子传输层包括ZnMgO纳米粒子，所述第二电子传输层包括ZnO纳米粒子或ZnMgO纳米粒子，所述第一电子传输层中Mg的摩尔百分比大于所述第二电子传输层中Mg的摩尔百分比。
例如，在本公开一实施例提供的发光结构中，所述第一电子传输层中Mg的摩尔百分比为10％-20％，所述第二电子传输层中Mg的摩尔百分比小于5％。
例如，在本公开一实施例提供的发光结构中，所述第一发光层和所述第二发光层至少之一为量子点发光层，所述第一阴极和第二阴极为同一导电层。
例如，本公开一实施例提供的发光结构还包括：第三发光元件，包括第三发光层、第三电子传输层和第三阴极，所述第三阴极与所述第三电子传输层接触设置，所述第三发光层的导带底能级大于所述第一发光层的导带底能级，小于所述第二发光层的导带底能级，所述第三电子传输层的导带底能级小于所述第一电子传输层的导带底能级，所述第三电子传输层的导带底能级大于所述第二电子传输层的导带底能级。
例如，在本公开一实施例提供的发光结构中，电子从所述第三阴极到所述第三电子传输层的势垒大于电子从所述第二阴极到所述第二电子传输层的势垒，且小于电子从所述第一阴极到所述第一电子传输层的势垒。
例如，在本公开一实施例提供的发光结构中，所述第一电子传输层包括ZnMgO纳米粒子，所述第二电子传输层包括ZnO纳米粒子或ZnMgO纳米粒子，所述第三电子传输层包括ZnMgO纳米粒子，所述第三电子传输层中Mg的摩尔百分比小于所述第一电子传输层中Mg的摩尔百分比，且大于所述第二电子传输层中Mg的摩尔百分比。
例如，在本公开一实施例提供的发光结构中，所述第一电子传输层中Mg的摩尔百分比为10％-20％，所述第二电子传输层中Mg的摩尔百分比小于5％，所述第三电子传输层中Mg的摩尔百分比为5％-10％。
例如，在本公开一实施例提供的发光结构中，所述第一电子传输层的电子迁移率小于所述第二电子传输层的电子迁移率。
例如，在本公开一实施例提供的发光结构中，所述第三电子传输层的电子迁移率大于所述第二电子传输层的电子迁移率，且小于所述第二电子传输层的电子迁移率。
例如，在本公开一实施例提供的发光结构中，所述第一发光层被配置为发红光，所述第二发光层被配置为发蓝光。
例如，在本公开一实施例提供的发光结构中，所述第一发光层被配置为发红光，所述第二发光层被配置为发蓝光，所述第三发光层被配置为发绿光。
本公开至少一个实施例还提供一种显示面板，包括阵列设置的多个发光结构，各所述发光结构为上述的发光结构。
本公开至少一个实施例还提供一种显示装置，包括上述的显示面板。
附图说明
为了更清楚地说明本公开实施例的技术方案，下面将对实施例的附图作简单地介绍，显而易见地，下面描述中的附图仅仅涉及本公开的一些实施例，而非对本公开的限制。
图1为根据本公开一实施例提供的一种发光结构的结构示意图；
图2为根据本公开一实施例提供的一种发光结构的第一发光元件采用不同电子传输层的电子注入效率和空穴注入效率的对比图；
图3为根据本公开一实施例提供的一种发光结构的第一发光元件采用不同电子传输层的电流效率的对比图；
图4为根据本公开一实施例提供的一种发光结构中不同发光层和不同电子传输层的能级示意图；以及
图5为根据本公开一实施例提供的另一种发光结构中不同发光层和不同电子传输层的能级示意图。
具体实施方式
为使本公开实施例的目的、技术方案和优点更加清楚，下面将结合本公开实施例的附图，对本公开实施例的技术方案进行清楚、完整地描述。显然，所描述的实施例是本公开的一部分实施例，而不是全部的实施例。基于所描述的本公开的实施例，本领域普通技术人员在无需创造性劳动的前提下所获得的所有其他实施例，都属于本公开保护的范围。
除非另外定义，本公开使用的技术术语或者科学术语应当为本公开所属领域内具有一般技能的人士所理解的通常意义。本公开中使用的“第一”、“第二”以及类似的词语并不表示任何顺序、数量或者重要性，而只是用来区分不同的组成部分。“包括”或者“包含”等类似的词语意指出现该词前面的元件或者物件涵盖出现在该词后面列举的元件或者物件及其等同，而不排除其他元件或者物件。“连接”或者“相连”等类似的词语并非限定于物理的或者机械的连接，而是可以包括电性的连接，不管是直接的还是间接的。
在通常的QLED器件中，由于量子点材料的能级位置等原因，红、绿量子点发光层的电子注入效率普遍优于空穴注入效率，导致红、绿量子点发光层的载流子中电子的数量大于空穴的数量；相反地，蓝色量子点发光层的电子注入效率弱于空穴注入效率，导致蓝色量子点发光层的载流子中空穴的数量大于电子的数量。因此，QLED器件中的量子点发光层的电子和空穴的不平衡，而电 子-空穴的不平衡不仅仅会减少注入的电荷转化为激子的能力，也会使得电荷在QLED器件内累积，增加了带电激子的非辐射跃迁，使得效率降低和使用寿命衰减，从而成为限制QLED器件效率和稳定性进一步提高的瓶颈。
对此，本公开实施例提供一种发光结构、显示面板和显示装置。该发光结构包括第一发光元件；第一发光元件包括第一发光层、第一电子传输层和第一阴极；第一阴极与第一电子传输层接触设置，第一电子传输层的导带底能级大于第一阴极的费米能级，第一电子传输层的导带底能级与第一阴极的费米能级之差的范围在0.3-0.6eV。在该发光结构中，由于第一电子传输层的导带底能级大于第一阴极的费米能级，因此电子从第一阴极到第一电子传输层需要跨越势垒，并且第一电子传输层的导带底能级与第一阴极的费米能级之差的范围在0.3-0.6eV，从而可适当地降低第一发光元件的电子注入效率并与第一发光元件的空穴注入效率相匹配，进而提高第一发光元件的发光效率和稳定性。
下面，结合附图对本公开实施例提供的发光结构、显示面板和显示装置进行说明。
图1为根据本公开一实施例提供的一种发光结构的结构示意图。如图1所示，该发光结构100包括第一发光元件110；第一发光元件110包括第一发光层111、第一电子传输层112和第一阴极113；第一阴极113与第一电子传输层112接触设置，在第一发光元件110进行发光时，第一阴极113用于提供电子。第一电子传输层112的导带底能级大于第一阴极113的费米能级，第一电子传输层112的导带底能级与第一阴极113的费米能级之差的范围在0.3-0.6eV。需要说明的是，上述的“接触设置”是指直接接触的情况，第一阴极与第一电子传输层之间不再设置其他膜层结构。
在本公开实施例提供的发光结构中，当第一发光层的电子注入效率优于空穴注入效率时，由于第一电子传输层的导带底能级大于第一阴极的费米能级，因此电子从第一阴极到第一电子传输层需要跨越势垒，并且第一电子传输层的导带底能级与第一阴极的费米能级之差的范围在0.3-0.6eV，从而可适当地降低第一发光元件的电子注入效率并与第一发光元件的空穴注入效率相匹配，进而提高第一发光元件的发光效率和稳定性。
例如，在一些示例中，如图1所示，第一发光层111和第一电子传输层112接触设置，也就是说，第一发光元件110不设置电子注入层，从而可在降低第一发光元件110的电子注入效率的同时降低第一发光元件110的厚度，从而可 提供一种轻薄的发光结构。
例如，在一些示例中，第一发光层111可为红色量子点发光层。由于通常的红色量子点发光层的电子注入效率普遍优于空穴注入效率，导致红色量子点发光层的载流子中的空穴和电子十分不平衡；而本公开实施例提供的发光结构通过选择合适的材料使得第一电子传输层的导带底能级大于第一阴极的费米能级，并且第一电子传输层的导带底能级与第一阴极的费米能级之差的范围在0.3-0.6eV，使得第一发光元件的电子注入效率和空穴注入效率相匹配，从而可提高第一发光元件的发光效率和稳定性。
例如，在一些示例中，第一发光层111的材料可包括无镉量子点材料，从而降低对环境的污染。第一电子传输层112包括ZnMgO纳米粒子，即掺杂Mg的ZnO纳米粒子，并且第一电子传输层112中Mg的摩尔百分比为10％-20％，从而可使得第一电子传输层112的导带底能级与第一阴极113的费米能级之差的范围在0.3-0.6eV。
例如，在一些示例中，第一阴极113的材料可为银或铝。由此，第一阴极113的费米能级可在-4.3到-4.2eV的范围。
例如，在一些示例中，第一发光层111的材料可包括磷化铟(InP)，第一电子传输层112中Mg的摩尔百分比为13％-16％。此时，第一电子传输层112的导带底能级大致为-3.83eV，而第一阴极113的费米能级范围可为-4.3到
-4.2eV，从而使得第一电子传输层112的导带底能级与第一阴极113的费米能级之差大致为0.37-0.47eV。此时，第一发光元件110的发光效率和稳定性可大大增加。
图2为根据本公开一实施例提供的一种发光结构的第一发光元件采用不同电子传输层的电子注入效率和空穴注入效率的对比图；图3为根据本公开一实施例提供的一种发光结构的第一发光元件采用不同电子传输层的电流效率的对比图。图2和图3中的第一发光元件为红色量子点发光元件，第一发光层采用磷化铟(InP)制作。
如图2所示，曲线1为第一发光元件的空穴注入效率；曲线2为电子传输层采用Mg的摩尔百分比为15％的ZnMgO纳米粒子的第一发光元件的电子注入效率；曲线3为电子传输层采用Mg的摩尔百分比为5％的ZnMgO纳米粒子的第一发光元件的电子注入效率；曲线4为电子传输层采用ZnO纳米粒子或者Mg的摩尔百分比为0％的ZnMgO纳米粒子，即ZnO纳米粒子的第一发光 元件的电子注入效率。实验结果显示，曲线2所示的电子注入效率和曲线1所示的空穴注入效率更加匹配，有利于提高第一发光元件的发光效率和稳定性。需要说明的是，曲线1的空穴注入效率是在第一发光元件仅包括发光层和空穴传输层测得的曲线；曲线2的电子注入效率是在第一发光元件仅包括发光层和电子传输层测得的曲线；曲线3的电子注入效率是在第一发光元件仅包括发光层和电子传输层测得的曲线；曲线4的电子注入效率是在第一发光元件仅包括发光层和电子传输层测得的曲线。
如图3所示，曲线5为电子传输层采用Mg的摩尔百分比为15％的ZnMgO纳米粒子的第一发光元件的电流效率；曲线6为电子传输层采用Mg的摩尔百分比为5％的ZnMgO纳米粒子的第一发光元件的电流效率；曲线7为电子传输层采用ZnO纳米粒子或者Mg的摩尔百分比为0％的ZnMgO纳米粒子，即ZnO纳米粒子的第一发光元件的电流效率。实验结果显示，曲线5所示的第一发光元件的电流效率明显高于曲线6和曲线7；并且，随着Mg的摩尔百分比的提高，曲线5所示的第一发光元件的电流效率并非线性提高，而是发生突变，大大高于曲线6和曲线7。由此，当电子传输层采用Mg的摩尔百分比为15％的ZnMgO纳米粒子时，第一发光元件具有较高的电流效率。需要说明的是，曲线5、曲线6和曲线7所示的第一发光元件的其他膜层(例如，空穴传输层等)均采用相同的材料和结构。
例如，在一些示例中，如图1所示，第一发光元件110还包括第一空穴传输层114、第一空穴注入层115和第一阳极116。第一空穴传输层114设置在第一发光层111远离第一电子传输层112的一侧，第一空穴注入层115设置在第一空穴传输层114远离第一发光层111的一侧，第一阳极116设置在第一空穴注入层115远离第一空穴传输层114的一侧。
例如，第一阳极116可采用透明导电氧化物或者导电聚合物，透明导电氧化物可为氧化铟锡(ITO)、FTO(SnO 2)等。另外，第一空穴传输层114和第一空穴注入层115的材料可根据实际情况进行选择，本公开实施例在此不作限制。
例如，在一些示例中，如图1所示，该发光结构还包括衬底基板101，用于承载上述的第一发光元件110。例如，衬底基板101可为透明基板，例如，玻璃基板、石英基板、塑料基板等。衬底基板101也可为柔性透明基板，例如，聚对苯二甲酸类塑料(PET)基板。
例如，在一些示例中，如图1所示，该发光结构100还包括第二发光元件120；第一发光元件110和第二发光元件120可用于发出不同颜色的光。第二发光元件120包括第二发光层121、第二电子传输层122和第二阴极123。第二阴极123与第二电子传输层122接触设置，第一发光层111的导带底能级小于第二发光层121的导带底能级，第一电子传输层112的导带底能级大于第二电子传输层122的导带底能级。
在该示例提供的发光结构中，不同的发光元件(例如第一发光元件和第二发光元件)采用不同材料制作的电子传输层。由于第一发光层111的导带底能级小于第二发光层121的导带底能级，电子从第一电子传输层112到第一发光层111的难度小于电子从第二电子传输层122到第二发光层121的难度，此时，由于第一电子传输层112的导带底能级大于第二电子传输层122的导带底能级，当第一阴极113和第二阴极123的费米能级大致相同时，电子从第一阴极113到第一传输层112的势垒大于电子从第二阴极123到第二电子传输层122的势垒，从而在一定程度上降低了电子注入第一发光层111的效率，从而与第一发光层111中的空穴注入效率达到平衡；并且，由于第一电子传输层112的导带底能级大于第二电子传输层122的导带底能级，该示例提供的发光结构还可降低电子从第二阴极123到第二电子传输层122的势垒，在一定程度上提高了电子注入第二发光层121的效率，从而与第二发光层121中的空穴注入效率达到平衡，进而同时提高了第一发光元件110和第二发光元件120的发光效率和稳定性。
例如，在一些示例中，第一阴极113和第二阴极123为同一导电层，即第一发光元件110和第二发光元件120共用阴极层。此时，电子从第一阴极113到第一电子传输层112的势垒大于电子从第二阴极123到第二电子传输层122的势垒。
图4为根据本公开一实施例提供的一种发光结构中不同发光层和不同电子传输层的能级示意图。如图4所示，第一发光层111的导带底能级小于第一电子传输层112的导带底能级，第二发光层121的导带底能级大于第二电子传输层122的导带底能级，也就是说，电子从第一电子传输层112到第一发光层111不存在或几乎不存在势垒，而电子从第二电子传输层122到第二发光层121需要跨越势垒。此时，第二阴极123的费米能级与第二电子传输层122的导带底能级大致相等，也就是说，电子从第二阴极123到第二电子传输层122不存在 或几乎不存在势垒。由此，该发光结构可在一定程度上提高电子从第二阴极123到第二发光层121的电子注入效率，从而与第二发光层121中的空穴注入效率达到平衡，从而提高第二发光元件120的发光效率和稳定性。需要说明的是，上述的第二阴极的费米能级与第二电子传输层的导带底能级大致相等是指第二阴极的费米能级与第二电子传输层的导带底能级的差值与第二阴极的费米能级的绝对值的比例范围在4％之内。
例如，在一些示例中，第一电子传输层112包括ZnMgO纳米粒子，第二电子传输层122包括ZnO纳米粒子或ZnMgO纳米粒子，第一电子传输层112中Mg的摩尔百分比大于第二电子传输层122中Mg的摩尔百分比。
例如，在一些示例中，第一电子传输层112中Mg的摩尔百分比为10％-20％，第二电子传输层122中Mg的摩尔百分比小于5％。需要说明的是，当第二电子传输层122为ZnO纳米粒子时，可认为第二电子传输层122为Mg的摩尔百分比为0的ZnMgO纳米粒子。
表1为根据本公开一实施例提供的一种电子传输层的能级数据表。在表1中，第一电子传输层112为Mg的摩尔百分比为15％的ZnMgO纳米粒子，第二电子传输层122为Mg的摩尔百分比为0％的ZnMgO纳米粒子。可见，第一电子传输层112的导带底能级大于第二电子传输层122的导带底能级。当第一阴极113和第二阴极123的费米能级范围为-4.3到-4.2eV时，第一电子传输层112的导带底能级与第一阴极113的费米能级之差大致为0.37-0.47eV，第二电子传输层122的导带底能级与第二阴极123的费米能级之差小于0.1eV。由此，该发光结构可在一定程度上降低了电子注入第一发光层111的效率，从而与第一发光层111中的空穴注入效率达到平衡；并且在一定程度上提高了电子注入第二发光层121的效率，从而与第二发光层121中的空穴注入效率达到平衡。
Figure PCTCN2020076750-appb-000001
表1-电子传输层的能级数据表
例如，在一些示例中，第一电子传输层112的电子迁移率小于第二电子传输层122的电子迁移率，从而也在一定程度上降低了电子注入第一发光层111的效率，从而与第一发光层111中的空穴注入效率达到平衡；并且在一定程度 上提高了电子注入第二发光层121的效率，从而与第二发光层121中的空穴注入效率达到平衡。例如，当第一电子传输层112为Mg的摩尔百分比为15％的ZnMgO纳米粒子，第二电子传输层122为Mg的摩尔百分比为0％的ZnMgO纳米粒子时，第一电子传输层112的电子迁移率小于第二电子传输层122的电子迁移率。
例如，在一些示例中，第一发光层和第二发光层至少之一为量子点发光层。例如，第一发光层可为红色量子点发光层，第二发光层可为蓝色量子点发光层；第一发光层可采用红色无镉量子点发光材料，例如，磷化铟(InP)，例如InP/ZnS核壳量子点材料；第二发光层可采用蓝色量子点发光材料，例如，硒化镉(CdSe)，例如CdSe/ZnS核壳量子点材料。
例如，在一些示例中，如图1所示，第二发光元件120还包括第二空穴传输层124、第二空穴注入层125和第二阳极116。第二空穴传输层124设置在第二发光层121远离第二电子传输层122的一侧，第二空穴注入层125设置在第二空穴传输层124远离第二发光层121的一侧，第二阳极126设置在第二空穴注入层125远离第二空穴传输层124的一侧。
例如，第二阳极126可采用透明导电氧化物或者导电聚合物，透明导电氧化物可为氧化铟锡(ITO)、FTO(SnO2)等。另外，第二空穴传输层124和第二空穴注入层125的材料可根据实际情况进行选择，本公开实施例在此不作限制。
例如，在一些示例中，如图1所示，第一发光元件110和第二发光元件120同层设置在衬底基板101上。也就是说，第一发光元件110的第一阳极116和第二发光元件120的第二阳极126可同层设置；第一发光元件110的第一空穴注入层115和第二发光元件120的第二空穴注入层125可同层设置；第一发光元件110的第一空穴传输层114和第二发光元件120的第二空穴传输层124可同层设置；第一发光元件110的第一发光层111和第二发光元件120的第二发光层121可同层设置；第一发光元件110的第一电子传输层112和第二发光元件120的第二电子传输层122可同层设置。需要说明的是，第一空穴注入层115和第二空穴注入层125可根据实际情况选择不同的厚度；第一空穴传输层114和第二空穴传输层124可根据实际情况选择不同的厚度。
例如，由于第一阳极116和第二阳极126可采用相同的材料制作，因此，第一阳极116和第二阳极126可采用同一导电层图案化形成。
例如，衬底基板101可为透明基板，例如，玻璃基板、石英基板、塑料基板等。衬底基板101也可为柔性透明基板，例如，聚对苯二甲酸类塑料(PET)基板。
例如，在一些示例中，如图1所示，该发光结构100还包括第三发光元件130；第三发光元件130包括第三发光层131、第三电子传输层132和第三阴极133。第三阴极133与第三电子传输层132接触设置，第三发光层131的导带底能级大于第一发光层111的导带底能级，小于第二发光层121的导带底能级，第三电子传输层132的导带底能级小于第一电子传输层112的导带底能级，第三电子传输层132的导带底能级大于第二电子传输层122的导带底能级。
在该示例提供的发光结构中，不同的发光元件(例如第一发光元件和第二发光元件)采用不同材料的电子传输层。由于第三发光层131的导带底能级大于第一发光层111的导带底能级，小于第二发光层121的导带底能级，即第三发光层131的导带底能级介于第一发光层111和第二发光层121之间，电子从第三电子传输层132到第三发光层131的难度也介于电子从第一电子传输层112到第一发光层111的难度和电子从第二电子传输层122到第二发光层121的难度之间，此时，由于第三电子传输层132的导带底能级小于第一电子传输层112的导带底能级，且大于第二电子传输层122的导带底能级，当第一阴极113、第二阴极123和第三阴极133的费米能级大致相同时，电子从第三阴极133到第三传输层132的势垒小于电子从第一阴极113到第一电子传输层112的势垒，且大于电子从第二阴极123到第二电子传输层122的势垒，从而在一定程度上降低了电子注入第三发光层131的效率，从而与第三发光层131中的空穴注入效率达到平衡，进而可同时提高第一发光元件110、第二发光元件120和第三发光元件130的发光效率和稳定性。
例如，在一些示例中，第一阴极113、第二阴极123和第三阴极133为同一导电层，即第一发光元件110、第二发光元件120和第三发光元件130共用阴极层。电子从第三阴极133到第三电子传输层132的势垒大于电子从第二阴极123到第二电子传输层122的势垒，且小于电子从第一阴极113到第一电子传输层112的势垒。
图5为根据本公开一实施例提供的另一种发光结构中不同发光层和不同电子传输层的能级示意图。如图5所示，第一发光层111的导带底能级小于第一电子传输层112的导带底能级，第二发光层121的导带底能级大于第二电子传 输层122的导带底能级，第三发光层131的导带底能级略大于第三电子传输层132的导带底能级。也就是说，电子从第一电子传输层112到第一发光层111不存在或几乎不存在势垒，电子从第二电子传输层122到第二发光层121需要跨越较大的势垒(相对于第三发光元件)，电子从第三电子传输层132到第三发光层131需要跨越较小的势垒。此时，电子从第一阴极113到第一电子传输层112的势垒较大，电子从第二阴极123到第二电子传输层122不存在或几乎不存在势垒，电子从第三阴极133到第三电子传输层132的势垒较小。由此，该发光结构可较大地提高降低电子从第一阴极113到第一发光层111的电子注入效率，较小地降低电子从第三阴极133到第三发光层131的电子注入效率，并且提高电子从第二阴极123到第二发光层121的电子注入效率，从而同时使得第一发光层111、第二发光层121和第三发光层131中的空穴-电子注入效率达到平衡，从而提高该发光结构的发光效率和稳定性。
例如，在一些示例中，第一电子传输层112包括ZnMgO纳米粒子，第二电子传输层122包括ZnO纳米粒子或ZnMgO纳米粒子，第三电子传输层132包括ZnMgO纳米粒子，第三电子传输层132中Mg的摩尔百分比小于第一电子传输层112中Mg的摩尔百分比，且大于第二电子传输层122中Mg的摩尔百分比。
例如，在一些示例中，第一电子传输层112中Mg的摩尔百分比为10％-20％，第二电子传输层122中Mg的摩尔百分比小于5％，第三电子传输层132中Mg的摩尔百分比为5％-10％。需要说明的是，当第二电子传输层122为ZnO纳米粒子时，可认为第二电子传输层122为Mg的摩尔百分比为0的ZnMgO纳米粒子。
表2为根据本公开一实施例提供的另一种电子传输层的能级数据表。在表2中，第一电子传输层112为Mg的摩尔百分比为15％的ZnMgO纳米粒子，第二电子传输层122为Mg的摩尔百分比为0％的ZnMgO纳米粒子，第三电子传输层132为Mg的摩尔百分比为5％的ZnMgO纳米粒子。可见，第一电子传输层112的导带底能级大于第三电子传输层132的导带底能级，第三电子传输层132的导带底能级大于第二电子传输层122的导带底能级。当第一阴极113、第二阴极123和第三阴极133的费米能级范围为-4.3到-4.2eV时，第一电子传输层112的导带底能级与第一阴极113的费米能级之差大致为0.37-0.47eV，第二电子传输层122的导带底能级与第二阴极123的费米能级之差小于 0.1eV，第三电子传输层132的导带底能级与第三阴极133的费米能级之差小于0.2eV。由此，该发光结构可在一定程度上降低了电子注入第一发光层111的效率，从而与第一发光层111中的空穴注入效率达到平衡，在一定程度上提高了电子注入第二发光层121的效率，从而与第二发光层121中的空穴注入效率达到平衡，并且在一定程度上降低了电子注入第三发光层131的效率，从而与第三发光层131中的空穴注入效率达到平衡。
Figure PCTCN2020076750-appb-000002
表2-电子传输层的能级数据表
例如，在一些示例中，第三电子传输层132的电子迁移率大于第二电子传输层122的电子迁移率，且小于第二电子传输层112的电子迁移率。由此，由此，该发光结构可进一步较大地提高降低电子从第一阴极113到第一发光层111的电子注入效率，较小地降低电子从第三阴极133到第三发光层131的电子注入效率，并且提高电子从第二阴极123到第二发光层121的电子注入效率，从而同时使得第一发光层111、第二发光层121和第三发光层131中的空穴-电子注入效率达到平衡，从而提高该发光结构的发光效率和稳定性。
例如，当第一电子传输层112为Mg的摩尔百分比为15％的ZnMgO纳米粒子，第二电子传输层122为Mg的摩尔百分比为0％的ZnMgO纳米粒子，第三电子传输层132为Mg的摩尔百分比为5％的ZnMgO纳米粒子时，第三电子传输层132的电子迁移率大于第二电子传输层122的电子迁移率，且小于第二电子传输层112的电子迁移率。
例如，在一些示例中，第一发光层可为红色量子点发光层，第二发光层可为蓝色量子点发光层，第三发光层为绿色量子点发光层；第一发光层可采用红色无镉量子点发光材料，例如，磷化铟(InP)，例如InP/ZnS核壳量子点材料；第二发光层可采用蓝色量子点发光材料，例如，硒化镉(CdSe)，例如CdSe/ZnS核壳量子点材料；第三发光层可采用绿色无镉量子点发光材料，例如，磷化铟(InP)，例如InP/ZnS核壳量子点材料。
例如，在一些示例中，如图1所示，第三发光元件130还包括第三空穴传输层134、第三空穴注入层135和第三阳极136。第三空穴传输层134设置在 第三发光层131远离第三电子传输层132的一侧，第三空穴注入层135设置在第三空穴传输层134远离第三发光层131的一侧，第三阳极136设置在第三空穴注入层135远离第三空穴传输层134的一侧。
例如，第三阳极136可采用透明导电氧化物或者导电聚合物，透明导电氧化物可为氧化铟锡(ITO)、FTO(SnO2)等。另外，第三空穴传输层134和第三空穴注入层135的材料可根据实际情况进行选择，本公开实施例在此不作限制。
例如，在一些示例中，如图1所示，第一发光元件110、第二发光元件120和第三发光元件130可同层设置在衬底基板101上。也就是说，第一发光元件110的第一阳极116、第二发光元件120的第二阳极126和第三发光元件130的第三阳极136可同层设置；第一发光元件110的第一空穴注入层115、第二发光元件120的第二空穴注入层125和第三发光元件130的第三空穴注入层135可同层设置；第一发光元件110的第一空穴传输层114、第二发光元件120的第二空穴传输层124和第三发光元件130的第三空穴传输层134可同层设置；第一发光元件110的第一发光层111、第二发光元件120的第二发光层121和第三发光元件130的第三发光层131可同层设置；第一发光元件110的第一电子传输层112、第二发光元件120的第二电子传输层122和第三发光元件130的第三电子传输层132可同层设置。需要说明的是，第一空穴注入层115、第二空穴注入层125和第三空穴注入层135可根据实际情况选择不同的厚度；第一空穴传输层114、第二空穴传输层124和第三空穴传输层134可根据实际情况选择不同的厚度。
例如，由于第一阳极116、第二阳极126和第三阳极127可采用相同的材料制作，因此，第一阳极116、第二阳极126和第三阳极137可采用同一导电层图案化形成。
例如，衬底基板101可为透明基板，例如，玻璃基板、石英基板、塑料基板等。衬底基板101也可为柔性透明基板，例如，聚对苯二甲酸类塑料(PET)基板。
例如，如图1所示，该发光结构100还包括位于不同发光元件之间(例如，第一发光元件110和第二发光元件120之间，第二发光元件120和第三发光元件130之间，第三发光元件130和第一发光元件110之间)的像素限定层180。
本公开至少一个实施例提供一种发光结构的制作方法。该制作方法包括以 下步骤S201-S205。
步骤S201：在衬底基板上形成第一阳极、第二阳极和第三阳极。
例如，可采用沉积方法在衬底基板上形成阳极层，然后图案化阳极层形成第一阳极、第二阳极和第三阳极；衬底基板可为透明基板，例如，玻璃基板、石英基板、塑料基板等；阳极层可采用透明导电氧化物或者导电聚合物，透明导电氧化物可为氧化铟锡(ITO)、FTO(SnO 2)等。
步骤S202：在第一阳极、第二阳极和第三阳极远离衬底基板的一侧分别形成第一空穴注入层、第二空穴注入层和第三空穴注入层。
例如，可采用喷墨打印或者纳米压印的方式在第一阳极、第二阳极和第三阳极远离衬底基板的一侧分别形成第一空穴注入层、第二空穴注入层和第三空穴注入层。第一空穴注入层、第二空穴注入层和第三空穴注入层的材料可为有机空穴注入材料，例如：PEDOT：PSS(聚(3,4-乙烯二氧噻吩)-聚苯乙烯磺酸)，或者无机氧化物，例如氧化钼(MoOx)。
步骤S203：在第一空穴注入层、第二空穴注入层和第三空穴注入层远离衬底基板的一测分别形成第一空穴传输层、第二空穴传输层和第三空穴传输层。
例如，第一空穴传输层、第二空穴传输层和第三空穴传输层可为有机空穴传输材料，例如，PVK(聚乙烯咔唑)、TFB(聚(9,9-二辛基芴-CO-N-(4-丁基苯基)二苯胺))和TPD(N,N’-diphenyl-N,N’-bis(3-methyllphenyl)-(1,1’-biphenyl)-4,4’-diamine)及其衍生物，或者无机空穴传输材料，例如氧化镍(NiOx)和氧化钒(VOx)。
步骤S204：在第一空穴传输层、第二空穴传输层和第三空穴传输层远离衬底基板的一侧分别形成第一发光层、第二发光层和第三发光层。
步骤S205：在第一发光层、第二发光层和第三发光层远离衬底基板的一侧分别形成第一电子传输层、第二电子传输层和第三电子传输层。
例如，第一电子传输层为Mg的摩尔百分比为10％-20％的ZnMgO纳米粒子，第二电子传输层为Mg的摩尔百分比小于5％的ZnMgO纳米粒子，第三电子传输层为Mg的摩尔百分比为5％-10％的ZnMgO纳米粒子。
步骤S206：在第一电子传输层、第二电子传输层和第三电子传输层远离衬底基板的一侧形成阴极层。
例如，可采用蒸镀的方式在第一电子传输层、第二电子传输层和第三电子传输层远离衬底基板的一侧形成阴极层；阴极层的材料可为铝或银；阴极层的 厚度范围可为100-150纳米。
本公开至少一个实施例还提供一种显示面板。该显示面板包括阵列设置的多个发光结构100，该发光结构为上述实施例提供的发光结构。由此，该显示面板可适当地降低第一发光元件的电子注入效率并与第一发光元件的空穴注入效率相匹配，进而提高第一发光元件的发光效率和稳定性。并且，当该显示面板采用上述实施例中不同发光元件采用不同的电子传输层的发光结构时，该显示面板可同时提高第一发光元件、第二发光元件和第三发光元件的发光效率和稳定性，具体可参见发光结构的实施例的具体描述。
本公开至少一个实施例还提供一种显示装置，包括上述实施例提供的显示面板。由此，该显示面板可适当地降低第一发光元件的电子注入效率并与第一发光元件的空穴注入效率相匹配，进而提高第一发光元件的发光效率和稳定性。并且，当该显示面板采用上述实施例中不同发光元件采用不同的电子传输层的发光结构时，该显示面板可同时提高第一发光元件、第二发光元件和第三发光元件的发光效率和稳定性，具体可参见发光结构的实施例的具体描述。
例如，在一些示例中，该显示装置可以为智能手机、平板电脑、电视机、显示器、笔记本电脑、数码相框、导航仪等任何具有显示功能的产品或部件。
(1)本公开实施例附图中，只涉及到与本公开实施例涉及到的结构，其他结构可参考通常设计。
(2)在不冲突的情况下，本公开同一实施例及不同实施例中的特征可以相互组合。
以上，仅为本公开的具体实施方式，但本公开的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本公开揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本公开的保护范围之内。因此，本公开的保护范围应以权利要求的保护范围为准。

Claims (20)

  1. 一种发光结构，包括：
    第一发光元件，包括第一发光层、第一电子传输层和第一阴极，
    其中，所述第一阴极与所述第一电子传输层接触设置，所述第一电子传输层的导带底能级大于所述第一阴极的费米能级，所述第一电子传输层的导带底能级与所述第一阴极的费米能级之差的范围在0.3-0.6eV。
  2. 根据权利要求1所述的发光结构，其中，所述第一发光层的导带底能级小于所述第一电子传输层的导带底能级，所述第一电子传输层包括ZnMgO纳米粒子，所述第一电子传输层中Mg的摩尔百分比为10％-20％。
  3. 根据权利要求2所述的发光结构，其中，所述第一电子传输层中Mg的摩尔百分比为13％-16％。
  4. 根据权利要求2或3所述的发光结构，其中，所述第一发光层的材料包括红色无镉量子点材料。
  5. 根据权利要求4所述的发光结构，其中，所述第一发光层的材料包括磷化铟。
  6. 根据权利要求1-5中任一项所述的发光结构，还包括：
    第二发光元件，包括第二发光层、第二电子传输层和第二阴极，
    其中，所述第二阴极与所述第二电子传输层接触设置，所述第一发光层的导带底能级小于所述第二发光层的导带底能级，所述第一电子传输层的导带底能级大于所述第二电子传输层的导带底能级。
  7. 根据权利要求6所述的发光结构，其中，电子从所述第一阴极到所述第一电子传输层的势垒大于电子从所述第二阴极到所述第二电子传输层的势垒。
  8. 根据权利要求6所述的发光结构，其中，所述第一发光层的导带底能级小于所述第一电子传输层的导带底能级，所述第二发光层的导带底能级大于所述第二电子传输层的导带底能级，所述第二阴极的费米能级与所述第二电子传输层的导带底能级大致相等。
  9. 根据权利要求6-8中任一项所述的发光结构，其中，所述第一电子传输层包括ZnMgO纳米粒子，所述第二电子传输层包括ZnO纳米粒子或ZnMgO纳米粒子，所述第一电子传输层中Mg的摩尔百分比大于所述第二电子传输层 中Mg的摩尔百分比。
  10. 根据权利要求9所述的发光结构，其中，所述第一电子传输层中Mg的摩尔百分比为10％-20％，所述第二电子传输层中Mg的摩尔百分比小于5％。
  11. 根据权利要求6-10中任一项所述的发光结构，其中，所述第一发光层和所述第二发光层至少之一为量子点发光层，所述第一阴极和第二阴极为同一导电层。
  12. 根据权利要求6-11中任一项所述的发光结构，还包括：
    第三发光元件，包括第三发光层、第三电子传输层和第三阴极，
    其中，所述第三阴极与所述第三电子传输层接触设置，所述第三发光层的导带底能级大于所述第一发光层的导带底能级，小于所述第二发光层的导带底能级，所述第三电子传输层的导带底能级小于所述第一电子传输层的导带底能级，所述第三电子传输层的导带底能级大于所述第二电子传输层的导带底能级。
  13. 根据权利要求12所述的发光结构，其中，电子从所述第三阴极到所述第三电子传输层的势垒大于电子从所述第二阴极到所述第二电子传输层的势垒，且小于电子从所述第一阴极到所述第一电子传输层的势垒。
  14. 根据权利要求12所述的发光结构，其中，所述第一电子传输层包括ZnMgO纳米粒子，所述第二电子传输层包括ZnO纳米粒子或ZnMgO纳米粒子，所述第三电子传输层包括ZnMgO纳米粒子，所述第三电子传输层中Mg的摩尔百分比小于所述第一电子传输层中Mg的摩尔百分比，且大于所述第二电子传输层中Mg的摩尔百分比。
  15. 根据权利要求14所述的发光结构，其中，所述第一电子传输层中Mg的摩尔百分比为10％-20％，所述第二电子传输层中Mg的摩尔百分比小于5％，所述第三电子传输层中Mg的摩尔百分比为5％-10％。
  16. 根据权利要求6-15中任一项所述的发光结构，其中，所述第一电子传输层的电子迁移率小于所述第二电子传输层的电子迁移率。
  17. 根据权利要求12所述的发光结构，其中，所述第三电子传输层的电子迁移率大于所述第二电子传输层的电子迁移率，且小于所述第二电子传输层的电子迁移率。
  18. 根据权利要求6-17中任一项所述的发光结构，其中，所述第一发光层被配置为发红光，所述第二发光层被配置为发蓝光。
  19. 一种显示面板，包括阵列设置的多个发光结构，
    其中，各所述发光结构为根据权利要求1-18中任一项所述的发光结构。
  20. 一种显示装置，包括根据权利要求19所述的显示面板。
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