WO2022143882A1 - 一种量子点发光二极管及其制备方法 - Google Patents

一种量子点发光二极管及其制备方法 Download PDF

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WO2022143882A1
WO2022143882A1 PCT/CN2021/142995 CN2021142995W WO2022143882A1 WO 2022143882 A1 WO2022143882 A1 WO 2022143882A1 CN 2021142995 W CN2021142995 W CN 2021142995W WO 2022143882 A1 WO2022143882 A1 WO 2022143882A1
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layer
quantum dot
dot light
hole transport
emitting diode
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French (fr)
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严怡然
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Tcl科技集团股份有限公司
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    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
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    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H10K50/115—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising active inorganic nanostructures, e.g. luminescent quantum dots
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    • H10K50/14—Carrier transporting layers
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    • H10K2101/30—Highest occupied molecular orbital [HOMO], lowest unoccupied molecular orbital [LUMO] or Fermi energy values
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    • H10K2102/10—Transparent electrodes, e.g. using graphene
    • H10K2102/101—Transparent electrodes, e.g. using graphene comprising transparent conductive oxides [TCO]
    • H10K2102/102—Transparent electrodes, e.g. using graphene comprising transparent conductive oxides [TCO] comprising tin oxides, e.g. fluorine-doped SnO2
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    • H10K2102/101—Transparent electrodes, e.g. using graphene comprising transparent conductive oxides [TCO]
    • H10K2102/103—Transparent electrodes, e.g. using graphene comprising transparent conductive oxides [TCO] comprising indium oxides, e.g. ITO
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    • H10K2102/301—Details of OLEDs
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Definitions

  • the QLED device structure usually consists of an anode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and a cathode. Electrons and holes are injected from both ends of the cathode and the anode, respectively.
  • the point light-emitting layer emits compound light.
  • the existing electron transport layer is usually composed of nano-zinc oxide particles, which have high carrier concentration and mobility; the organic polymer materials used in the hole transport layer, such as PVK, TFB, etc.
  • the carrier mobility is low and the quantum dot energy level is too deep, which leads to the difficulty of hole injection, so that holes accumulate in the hole transport layer or the interface layer between the hole transport layer and the quantum dot light-emitting layer for a long time, and the excessive electrons accumulate.
  • the injection causes it to easily transition to the hole transport layer or its interface layer with the quantum dot light-emitting layer, which eventually leads to the recombination of electrons and holes at the non-emitting layer, which seriously affects the efficiency and lifetime of QLED devices.
  • the purpose of the present disclosure is to provide a quantum dot light emitting diode and a preparation method thereof, aiming at solving the problem of low luminous efficiency of the existing quantum dot light emitting diode.
  • a quantum dot light-emitting diode comprising a cathode, an anode, a quantum dot light-emitting layer disposed between the cathode and the anode, and a hole transport layer disposed between the anode and the quantum dot light-emitting layer, wherein the An interface layer is arranged between the hole transport layer and the quantum dot light-emitting layer, the interface layer material is sulfide, and the general structural formula of the sulfide is Li x By S z , wherein B is P, Si , one or more of Ge and Sn; the HOMO energy level of the interface layer is greater than the HOMO energy level of the hole transport layer and smaller than the HOMO energy level of the quantum dot light-emitting layer.
  • a preparation method of a quantum dot light-emitting diode comprising the steps of:
  • An interface layer is prepared on the hole transport layer, the interface layer material is sulfide, and the general structural formula of the sulfide is Li x By S z , wherein B is one of P, Si, Ge and Sn one or more;
  • a cathode is prepared on the quantum dot light-emitting layer to prepare the quantum dot light-emitting diode;
  • a cathode substrate is provided, and a quantum dot light-emitting layer is prepared on the cathode substrate;
  • An interface layer is prepared on the surface of the quantum dot light-emitting layer, the interface layer material is sulfide, and the general structural formula of the sulfide is Li x By S z , wherein B is one of P, Si, Ge and Sn. one or more;
  • An anode is prepared on the hole transport layer to prepare the quantum dot light emitting diode.
  • the present disclosure provides an interface layer between the hole transport layer and the quantum dot light-emitting layer, since the HOMO energy level of the interface layer is located between the HOMO energy levels of the hole transport layer and the quantum dot light-emitting layer. It can effectively reduce the injection barrier of holes, thereby reducing the deterioration of materials and devices caused by the accumulation of holes at the barrier interface; the interface layer can also effectively block electron tunneling and prevent electrons and holes The non-quantum dot light-emitting layer is recombined, thereby improving the light-emitting efficiency of the quantum dot light-emitting diode.
  • FIG. 1 is a schematic structural diagram of a preferred embodiment of a positive structure quantum dot light emitting diode disclosed.
  • FIG. 2 is a schematic structural diagram of a preferred embodiment of an inversion structure quantum dot light emitting diode disclosed.
  • FIG. 3 is a flow chart of a preferred embodiment of a method for fabricating a quantum dot light-emitting diode with a positive structure disclosed.
  • FIG. 4 is a flow chart of a preferred embodiment of a method for fabricating a quantum dot light-emitting diode with an inversion structure disclosed.
  • the present disclosure provides a quantum dot light-emitting diode and a preparation method thereof.
  • the present disclosure will be described in further detail below. It should be understood that the specific embodiments described herein are only used to explain the present disclosure, but not to limit the present disclosure.
  • quantum dot light-emitting diodes There are many forms of quantum dot light-emitting diodes, and the quantum dot light-emitting diodes are divided into formal structures and trans-structures.
  • the quantum-dot light-emitting diodes of the inverse structure may include substrates, cathodes, quantum dots stacked from bottom to top Light emitting layer, hole transport layer and anode.
  • the positive structure quantum dot light emitting diode as shown in FIG. 1 will be mainly introduced as an example.
  • the quantum dot light-emitting diode of the positive type structure comprises an anode arranged on the surface of the substrate, a hole transport layer arranged on the surface of the anode, an interface layer arranged on the surface of the hole transport layer, and arranged on the interface layer
  • the quantum dot light-emitting layer on the quantum dot light-emitting layer is arranged on the cathode on the surface of the quantum dot light-emitting layer, wherein the interface layer material is sulfide, and the general structural formula of the sulfide is Li x By S z , wherein B is One or more of P, Si, Ge and Sn, the HOMO energy level of the interface layer is greater than the HOMO energy level of the hole transport layer and smaller than the HOMO energy level of the quantum dot light-emitting layer.
  • an interface layer made of sulfide is arranged between the hole transport layer and the quantum dot light-emitting layer, and the HOMO energy level of the interface layer is greater than the HOMO energy level of the hole transport layer and smaller than the HOMO energy level of the hole transport layer.
  • the HOMO energy level of the quantum dot light-emitting layer, the interface layer can effectively reduce the injection barrier of holes, thereby reducing the material and device recession caused by the accumulation of holes at the barrier interface, thereby effectively improving the luminescence of quantum dot light-emitting diodes efficiency and service life.
  • the magnitude of the HOMO energy level in this embodiment refers to the magnitude of the absolute value of the HOMO energy level. That is to say, in this embodiment, the absolute value of the HOMO energy level of the interface layer is greater than the absolute value of the HOMO energy level of the hole transport layer and smaller than the absolute value of the HOMO energy level of the quantum dot light-emitting layer.
  • an interface layer composed of sulfide is arranged between the hole transport layer and the quantum dot light-emitting layer, the interface layer material is sulfide, and the general structural formula of the sulfide is Li x By S z , where B is one or more of P, Si, Ge and Sn, the sulfide has the properties of conducting ions and holes but not conducting electrons, therefore, the sulfide can not only effectively help Hole injection can also effectively prevent electrons from tunneling to the hole transport layer and prevent the device from emitting light in the non-light-emitting region, thereby improving the overall light-emitting efficiency of the quantum dot light-emitting diode.
  • the material used in the hole transport layer of the quantum dot light-emitting diode is usually an organic material, such as PEDOT (polythiophene), this type of material is more sensitive to water and oxygen, and the gradual penetration of water and oxygen from the encapsulant will affect the Stability of hole injection and transport, in this embodiment, the interfacial layer composed of sulfide is arranged between the hole transport layer and the quantum dot light-emitting layer, which can further effectively block the permeation of water and oxygen, thereby improving the service life of the device .
  • PEDOT polythiophene
  • the thickness of the interfacial layer is 10-200 nm, and within this range, the interfacial layer can not only improve the injection rate of holes, but also block the tunneling of electrons. If the thickness of the interface layer is less than 10 nm, the effect of blocking electron tunneling to the hole transport layer is poor; if the thickness of the interface layer is greater than 200 nm, the injection distance of holes is increased, which affects the transport of holes to quantum Efficiency of the point light-emitting layer.
  • the HOMO level of the interfacial layer is 4.9-6.0 eV.
  • the HOMO energy level of the hole transport layer is usually 4.9-5.4 eV
  • the HOMO energy level of the quantum dot light-emitting layer is usually 5.9-6.5 eV
  • the HOMO energy level of the interface layer is located in the hole transport layer. Therefore, it can effectively reduce the injection barrier of holes and promote the injection rate of holes, thereby reducing the deterioration of materials and devices caused by the accumulation of holes at the barrier interface. Effectively improve the luminous efficiency and service life of the quantum dot light-emitting diode.
  • the The HOMO energy level of the interface layer may be 5.4-6 eV.
  • the interface layer material is Li 3 PS 4 .
  • the HOMO energy level of the Li 3 PS 4 is located between the HOMO energy levels of the hole transport layer and the quantum dot light-emitting layer, so the interface layer can effectively reduce the hole injection barrier and promote The injection rate of holes can be reduced, thereby reducing the deterioration of materials and devices caused by the accumulation of holes at the barrier interface, thereby effectively improving the luminous efficiency and service life of quantum dot light-emitting diodes.
  • the hole transport layer material is selected from poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB), polyvinylcarbazole ( PVK), poly(N,N'bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (Poly-TPD), poly(9,9-dioctylfluorene-co- - Bis-N,N-phenyl-1,4-phenylenediamine) (PFB), 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA), 4,4'- Bis(9-carbazole)biphenyl (CBP), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'- One of diamine (TPD), N,N'-dipheny
  • the quantum dot light-emitting layer is selected from one or more of binary phase quantum dots, ternary phase quantum dots and quaternary phase quantum dots, but is not limited thereto.
  • the binary phase quantum dots are at least one of CdS, CdSe, CdTe, InP, AgS, PbS, PbSe, and HgS; and/or, the ternary phase quantum dots are Zn ⁇ Cd 1 - at least one of XS, CuXIn1 - XS, ZnXCd1 - XSe, ZnXSe1 - XS , ZnXCd1 - XTe , PbSeXS1 - X ; and/ Or, the quaternary phase quantum dots are ZnXCd1 - XS /ZnSe, CuXIn1 - XS /ZnS, ZnXCd1 - XSe/ZnS, CuInS
  • an electronic functional layer is disposed between the quantum dot light-emitting layer and the cathode, and the electronic functional layer includes a hole blocking layer, an electron injection layer and an electron transport layer, but is not limited thereto.
  • a hole injection layer is further provided between the anode and the hole transport layer.
  • the hole injection layer is one or more of PEDOT:PSS, WO 3 , MoO 3 and V 2 O 5 , but not limited thereto.
  • the hole injection layer has a thickness of 30-120 nm.
  • the cathode may be Au, Ag, Al, Cu, Mo or alloys thereof, but not limited thereto.
  • the anode has a thickness of 5-120 nm.
  • the hole transport layer has a thickness of 30-120 nm.
  • the quantum dot light-emitting layer has a thickness of 10-200 nm.
  • the electron transport layer has a thickness of 5-100 nm; the cathode has a thickness of 5-120 nm.
  • the anode is one or more of, but not limited to, ITO, FTO, ATO, AZO, GZO, IZO, MZO, and AMO.
  • the present disclosure also provides a quantum dot light emitting diode with an inversion structure.
  • the quantum dot light emitting diode with an inversion structure includes a cathode disposed on the surface of the substrate, and is disposed on the surface of the substrate.
  • the interface layer material is sulfide, and the general structural formula of the sulfide is Li x By S z , wherein B is one or more of P, Si, Ge and Sn, and the HOMO energy level of the interface layer is It is larger than the HOMO energy level of the hole transport layer and smaller than the HOMO energy level of the quantum dot light-emitting layer.
  • an interface layer made of sulfide is arranged between the hole transport layer and the quantum dot light-emitting layer, and the HOMO energy level of the interface layer is greater than the HOMO energy level of the hole transport layer and smaller than the HOMO energy level of the hole transport layer.
  • the HOMO energy level of the quantum dot light-emitting layer, the interface layer can effectively reduce the injection barrier of holes, thereby reducing the material and device recession caused by the accumulation of holes at the barrier interface, thereby effectively improving the luminescence of quantum dot light-emitting diodes efficiency and service life.
  • the interface layer material is a sulfide, and the general structural formula of the sulfide is Li x By S z , wherein B is one or more of P, Si, Ge and Sn, and the sulfide has a Conducting ions and holes, but not conducting electrons, the hole and ionic conductivity of the sulfide at room temperature is close to 10 -2 S/cm, and its electron conductivity is less than the ion/hole conductivity 4- More than 5 orders of magnitude, therefore, the sulfide can not only effectively help hole injection, but also effectively prevent electrons from tunneling to the hole transport layer, preventing the device from emitting light in the non-emitting region, thereby improving the overall luminous efficiency of quantum dot light-emitting diodes .
  • a method for preparing a quantum dot light-emitting diode with a positive structure as shown in FIG. 1 is also provided, as shown in FIG. 3 , which includes the steps:
  • the interface layer material is sulfide, the general structural formula of the sulfide is Li x By S z , wherein, B is P, Si, Ge and Sn one or more of;
  • the preparation methods of the above-mentioned layers may be chemical methods or physical methods, wherein chemical methods include but are not limited to chemical vapor deposition methods, continuous ion layer adsorption and reaction methods, anodic oxidation methods, electrolytic deposition methods, and co-precipitation methods.
  • physical methods include but are not limited to physical coating methods or solution methods, wherein solution methods include but are not limited to spin coating methods, printing methods, blade coating methods, dip-pulling methods, soaking methods, spraying methods, Roller coating method, casting method, slot coating method, strip coating method; physical coating methods include but are not limited to thermal evaporation coating method, electron beam evaporation coating method, magnetron sputtering method, multi-arc ion coating method, One or more of physical vapor deposition, atomic layer deposition, and pulsed laser deposition.
  • an interface layer is prepared on the hole transport layer by a spin coating method, which includes the steps of: dispersing the sulfide in an organic solvent to prepare a sulfide solution; dispersing the sulfide in an organic solvent; The solution was spin-coated on the surface of the hole transport layer, and thermally annealed at 100° C. for 30 minutes to obtain an interface layer.
  • the organic solvent includes ethanol, methanol, butanol, acetone, isoacetone, butyronitrile, chlorobenzene, toluene, xylene, dimethylformamide, dimethylsulfoxide, N-methyl Pyrrolidone, ethyl acetate, etc., but not limited thereto.
  • the concentration of the sulfide solution is 1-2 wt %. Within this concentration range, the prepared interface layer can not only reduce the interface impedance, but also effectively improve the light-emitting performance of the quantum dot light-emitting diode.
  • a preparation method of a quantum dot light-emitting diode with an inversion structure which includes the steps:
  • the present disclosure also provides a preparation method of a QLED with an inversion structure shown in FIG. 2 , as shown in FIG. 4 . It includes the following steps:
  • the interface layer material is sulfide, and the general structural formula of the sulfide is Li x By S z , wherein, B is P, Si, Ge and Sn one or more of;
  • an anode is prepared on the hole transport layer to prepare the quantum dot light-emitting diode.
  • the preparation method of the above-mentioned layers can be a chemical method or a physical method, wherein the chemical method includes but is not limited to one of chemical vapor deposition, continuous ion layer adsorption and reaction, anodization, electrolytic deposition, and co-precipitation.
  • physical methods include but are not limited to physical coating methods or solution methods, wherein solution methods include but are not limited to spin coating, printing, blade coating, dip-pulling, immersion, spraying, roll coating, casting method, slit coating method, strip coating method; physical coating methods include but are not limited to thermal evaporation coating method, electron beam evaporation coating method, magnetron sputtering method, multi-arc ion coating method, physical vapor deposition method, One or more of atomic layer deposition and pulsed laser deposition.
  • a quantum dot light-emitting diode and a preparation method thereof of the present disclosure will be further explained by the following examples:
  • Embodiment 1 of the present disclosure provides a method for preparing a quantum dot light-emitting diode with a positive bottom emission structure, which includes the following steps:
  • Step S1 depositing a hole injection layer on the transparent anode substrate, the transparent anode is ITO, the material of the hole injection layer is WO 3 , the thickness of the transparent anode is 20 nm, and the thickness of the hole injection layer is 60nm;
  • Step S2 depositing a hole transport layer on the hole injection layer, the material of the hole transport layer is PFB, and the thickness of the hole transport layer is 60 nm;
  • Step S3 depositing an interface layer on the hole transport layer, the interface layer material is Li 3 PS 4 , and the thickness of the interface layer is 100 nm;
  • Step S4 depositing a quantum dot light-emitting layer on the interface layer, the material of the quantum dot light-emitting layer is PbSe, and the thickness of the quantum dot light-emitting layer is 50 nm;
  • Step S5 depositing an electron transport layer on the quantum dot light-emitting layer, the material of the electron transport layer is TiO, and the thickness of the electron transport layer is 60 nm;
  • Step S6 depositing a metal cathode on the electron transport layer, the cathode material is Ag, the thickness of the cathode is 100 nm, and the reflection of the cathode to visible light is not less than 98%.
  • Embodiment 2 of the present disclosure provides a method for preparing a quantum dot light-emitting diode with a positive top emission structure, which includes the following steps:
  • Step S1 deposit a hole injection layer on the transparent anode substrate, the transparent anode is FTO, the material of the hole injection layer is WO 3 , the thickness of the transparent anode is 20 nm, and the thickness of the hole injection layer is 60nm;
  • Step S2 depositing a hole transport layer on the hole injection layer, the material of the hole transport layer is TCTA, and the thickness of the hole transport layer is 60 nm;
  • Step S3 depositing an interface layer on the hole transport layer, the interface layer material is Li 3 PS 4 , and the thickness of the interface layer is 100 nm;
  • Step S4 depositing a quantum dot light-emitting layer on the interface layer, the material of the quantum dot light-emitting layer is InP, and the thickness of the quantum dot light-emitting layer is 50 nm;
  • Step S5 depositing an electron transport layer on the quantum dot light-emitting layer, the material of the electron transport layer is NiO, and the thickness of the electron transport layer is 60 nm;
  • Step S6 depositing a cathode on the electron transport layer, the cathode material is Ag, the thickness of the cathode is 100 nm, and the transmittance of the cathode to visible light is not less than 90%.
  • Embodiment 3 of the present disclosure provides a method for preparing a quantum dot light-emitting diode with an inverted bottom emission structure, which includes the following steps:
  • Step S1 depositing an Ag layer on the substrate by means of evaporation, and the thickness of the Ag layer is 5 nm;
  • Step S2 deposit an electron transport layer on the Ag layer, the electron transport layer material is SnO, and the thickness of the electron transport layer is 50nm;
  • Step S3 depositing a quantum dot light-emitting layer on the electron transport layer, the material of the quantum dot light-emitting layer is CdSe, and the thickness of the quantum dot light-emitting layer is 50 nm;
  • Step S4 depositing an interface layer on the quantum dot light-emitting layer, the material of the interface layer is Li 3 PS 4 , and the thickness of the interface layer is 80 nm;
  • Step S5 depositing a hole transport layer on the interface layer, the material of the hole transport layer is PVK, and the thickness of the hole transport layer is 80 nm;
  • Step S6 depositing a hole injection layer on the hole transport layer, the material of the hole injection layer is PEDOT:PSS, and the thickness of the hole injection layer is 60 nm;
  • Step S7 depositing an anode on the hole injection layer, the anode material is ITO, the thickness of the anode is 120 nm; the reflection of the anode to visible light is not less than 98%.
  • Embodiment 4 of the present disclosure provides a method for preparing a quantum dot light-emitting diode with an inverted top emission structure, which includes the following steps:
  • Step S1 depositing an Ag layer on the substrate by means of evaporation, and the thickness of the Ag layer is 5 nm;
  • Step S2 depositing an electron transport layer on the Ag layer, the material of the electron transport layer is TiO, and the thickness of the electron transport layer is 60 nm;
  • Step S3 depositing a quantum dot light-emitting layer on the electron transport layer, the material of the quantum dot light-emitting layer is CdTe, and the thickness of the quantum dot light-emitting layer is 50 nm;
  • Step S4 depositing an interface layer on the quantum dot light-emitting layer, the material of the interface layer is Li 3 PS 4 , and the thickness of the interface layer is 80 nm;
  • Step S5 on the interface layer, depositing a hole transport layer, the material of the hole transport layer is PFB, and the thickness of the hole transport layer is 80 nm;
  • Step S6 depositing a hole injection layer on the hole transport layer, the material of the hole injection layer is MoO 3 , and the thickness of the hole injection layer is 60 nm;
  • Step S7 depositing an anode on the hole injection layer, the anode material is ITO, the thickness of the anode is 120 nm; the visible light transmission of the anode is not less than 90%.
  • the present disclosure also provides a pair of Example 1, including a method for preparing a quantum dot light-emitting diode with a positive bottom emission structure, which includes the following steps:
  • Step S1 depositing a hole injection layer on the transparent anode substrate, the transparent anode is ITO, the material of the hole injection layer is WO 3 , the thickness of the transparent anode is 20 nm, and the thickness of the hole injection layer is 60nm;
  • Step S2 depositing a hole transport layer on the hole injection layer, the material of the hole transport layer is PFB, and the thickness of the hole transport layer is 60 nm;
  • Step S3 depositing a quantum dot light-emitting layer on the hole transport layer, the material of the quantum dot light-emitting layer is PbSe, and the thickness of the quantum dot light-emitting layer is 50 nm;
  • Step S4 depositing an electron transport layer on the quantum dot light-emitting layer, the material of the electron transport layer is TiO, and the thickness of the electron transport layer is 60 nm;
  • Step S5 depositing a metal cathode on the electron transport layer, the cathode material is Ag, the thickness of the cathode is 100 nm, and the reflection of the cathode to visible light is not less than 98%.
  • the present disclosure also provides a pair of Example 2, including a method for preparing a quantum dot light-emitting diode with a positive top emission structure, which includes the following steps:
  • Step S1 deposit a hole injection layer on the transparent anode substrate, the transparent anode is FTO, the material of the hole injection layer is WO 3 , the thickness of the transparent anode is 20 nm, and the thickness of the hole injection layer is 60nm;
  • Step S2 depositing a hole transport layer on the hole injection layer, the material of the hole transport layer is TCTA, and the thickness of the hole transport layer is 60 nm;
  • Step S3 depositing a quantum dot light-emitting layer on the hole transport layer, the material of the quantum dot light-emitting layer is InP, and the thickness of the quantum dot light-emitting layer is 50 nm;
  • Step S4 depositing an electron transport layer on the quantum dot light-emitting layer, the material of the electron transport layer is NiO, and the thickness of the electron transport layer is 60 nm;
  • Step S5 depositing a cathode on the electron transport layer, the cathode material is Ag, the thickness of the cathode is 100 nm, and the transmittance of the cathode to visible light is not less than 90%.
  • the present disclosure also provides a pair of Example 3, including a method for preparing a quantum dot light-emitting diode with an inverted bottom emission structure, which includes the following steps:
  • Step S1 depositing an Ag layer on the substrate by means of evaporation, and the thickness of the Ag layer is 5 nm;
  • Step S2 depositing an electron transport layer on the Ag layer, the material of the electron transport layer is SnO, and the thickness of the electron transport layer is 50 nm;
  • Step S3 depositing a quantum dot light-emitting layer on the electron transport layer, the material of the quantum dot light-emitting layer is CdSe, and the thickness of the quantum dot light-emitting layer is 50 nm;
  • Step S4 depositing a hole transport layer on the quantum dot light-emitting layer, the hole transport layer material is PVK, and the thickness of the hole transport layer is 80 nm;
  • Step S5 depositing a hole injection layer on the hole transport layer, the material of the hole injection layer is PEDOT:PSS, and the thickness of the hole injection layer is 60 nm;
  • Step S6 depositing an anode on the hole injection layer, the anode material is ITO, the thickness of the anode is 120 nm; the reflection of the anode to visible light is not less than 98%.
  • the present disclosure also provides a pair of Example 4, including a method for preparing a quantum dot light-emitting diode with an inverted top emission structure, which includes the following steps:
  • Step S1 depositing an Ag layer on the substrate by means of evaporation, and the thickness of the Ag layer is 5 nm;
  • Step S2 depositing an electron transport layer on the Ag layer, the material of the electron transport layer is TiO, and the thickness of the electron transport layer is 60 nm;
  • Step S3 depositing a quantum dot light-emitting layer on the electron transport layer, the material of the quantum dot light-emitting layer is CdTe, and the thickness of the quantum dot light-emitting layer is 50 nm;
  • Step S4 depositing a hole transport layer on the quantum dot light-emitting layer, the hole transport layer material is PFB, and the thickness of the hole transport layer is 80 nm;
  • Step S6 depositing an anode on the hole injection layer, the anode material is ITO, the thickness of the anode is 120 nm; the visible light transmission of the anode is not less than 90%.
  • Example 1 and Comparative Example 1 Comparing the data in Table 1, it can be seen that the difference between Example 1 and Comparative Example 1 is only that an interface layer formed of Li 3 PS 4 material is added between the hole transport layer and the quantum dot light-emitting layer, and its external quantum efficiency is 7.9. % increased to 10.2%, and its service life was increased from 5.4h to 6.3h; the only difference between Example 2 and Comparative Example 2 was that between the hole transport layer and the quantum dot light-emitting layer, a material formed of Li 3 PS 4 was added. For the interface layer, its external quantum efficiency is increased from 14.6% to 16.3%, and its service life is increased from 3.9h to 5.0h; the difference between Example 3 and Comparative Example 3 is only the increase between the hole transport layer and the quantum dot light-emitting layer.

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Abstract

本公开涉及一种量子点发光二极管及其制备方法，所述量子点发光二极管包括设置在阴极和阳极之间的量子点发光层，以及设置在所述阳极和量子点发光层之间的空穴传输层，所述空穴传输层与所述量子点发光层之间设置有界面层，所述界面层材料为硫化物，所述硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种；所述界面层的HOMO能级大于所述空穴传输层的HOMO能级且小于所述量子点发光层的HOMO能级。本公开中，所述界面层可有效降低空穴注入势垒，提高空穴注入速率，同时有效防止电子发生隧穿与空穴在非量子点发光区复合，从而提高器件的发光效率。

Description

一种量子点发光二极管及其制备方法
优先权
本公开要求申请日为2020年12月31日，申请号为“202011636178.7”，申请名称为“一种量子点发光二极管及其制备方法”的中国专利申请的优先权，其全部内容通过引用结合在本公开中。
技术领域
本公开涉及量子点领域，尤其涉及一种量子点发光二极管及其制备方法。
背景技术
量子点发光二极管(QLED)具有色纯度高、较窄的半高峰宽发光效率高、发光颜色可调以及器件稳定等良好的特点，使得其在平板显示、固态照明等领域具有广泛的应用前景。随着研发的不断推进，量子点发光二极管的外量子效率(EQE)已有显著提高，其中，红光量子点发光二极管以及绿光量子点发光二极管的外量子效率均高于25％的水平，在效率上已可比拟有机发光二极管(OLED)，但蓝光量子点发光二极管的外量子效率及寿命上仍不足以满足要求。
与OLED器件较为相似，QLED器件结构通常由阳极、空穴注入层、空穴传输层、量子点发光层、电子传输层、阴极组成，电子和空穴分别从阴极和阳极两端注入，在量子点发光层复合发光。现有电子传输层通常由纳米氧化锌粒子组成，其有着较高的载流子浓度和迁移率；空穴传输层所使用的有机高分子材料，如PVK,TFB等，由于空穴传输层的载流子迁移率较低以及量子点能级过深而导致空穴注入困难，使得空穴长期在空穴传输层中或空穴传输层与量子点发光层的界面层积累，而电子的过度注入则导致其容易跃迁到空穴传输层或其与量子点发光层的界面层，最终导致电子和空穴在非发光层处发生复合，严重影响了QLED器件的效率及寿命。
因此，现有技术还有待于改进。
发明内容
鉴于上述现有技术的不足，本公开的目的在于提供一种量子点发光二极管及其制备方法，旨在解决由于现有量子点发光二极管发光效率低的问题。
本公开的技术方案如下：
一种量子点发光二极管，包括阴极、阳极，设置在所述阴极和阳极之间的量子点发光层，以及设置在所述阳极和量子点发光层之间的空穴传输层，其中，所述空穴传输层与所述量子点发光层之间设置有界面层，所述界面层材料为硫化物，所述硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种；所述界面层的HOMO能级大于所述空穴传输层的HOMO能级且小于所述量子点发光层的HOMO能级。
一种量子点发光二极管的制备方法，其中，包括步骤：
提供一种阳极基板，在所述阳极基板上空穴传输层；
在所述空穴传输层上制备界面层，所述界面层材料为硫化物，所述硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种；
在所述界面层制备量子点发光层；
在所述量子点发光层制备阴极，制得所述量子点发光二极管；
或者，提供一种阴极基板，在所述阴极基板上制备量子点发光层；
在所述量子点发光层表面制备界面层，所述界面层材料为硫化物，所述硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种；
在所述界面层制备空穴传输层；
在所述空穴传输层上制备阳极，制得所述量子点发光二极管。
有益效果：本公开通过在空穴传输层和量子点发光层之间设置界面层，由于所述界面层的HOMO能级位于所述空穴传输层与所述量子点发光层的HOMO能级之间，其可以有效降低空穴的注入势垒，从而减少由于空穴在势垒界面处积累而造成的材料及器件衰退；所述界面层还可有效阻挡电子隧穿，避免电子与空穴在非量子点发光层复合，从而提高量子点发光二极管的发光效率。
附图说明
图1为本公开一种正型结构量子点发光二极管较佳实施例的结构示意图。
图2为本公开一种反型结构量子点发光二极管较佳实施例的结构示意图。
图3为本公开一种正型结构量子点发光二极管的制备方法较佳实施例的流程图。
图4为本公开一种反型结构量子点发光二极管的制备方法较佳实施例的流程图。
具体实施方式
本公开提供一种量子点发光二极管及其制备方法，为使本公开的目的、技术方案及效果更加清楚、明确，以下对本公开进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本公开，并不用于限定本公开。
量子点发光二极管有多种形式，且所述量子点发光二极管分为正式结构和反式结构，所述反型结构的量子点发光二极管可包括从下往上层叠设置的基板、阴极、量子点发光层、空穴传输层以及阳极。而本公开的具体实施方式中将主要以如图1所示的正型结构的量子点发光二极管为实施例进行介绍。所述正型结构的量子点发光二极管包括设置在衬底表面的阳极，设置在所述阳极表面的空穴传输层，设置在所述空穴传输层表面的界面层，设置在所述界面层上的量子点发光层，设置在所述量子点发光层表面的阴极，其中，所述界面层材料为硫化物，所述硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种，所述界面层的HOMO能级大于所述空穴传输层的HOMO能级且小于所述量子点发光层的HOMO能级。
由于常用的空穴传输层的最高被占据能级(HOMO)与量子点发光层的功函数之间存在较大的势垒，使得空穴从空穴传输层注入到量子点发光层变得困难，导致空穴与电子的注入不平衡，严重影响量子点发光二极管的发光效率。本实施例通过在所述空穴传输层和量子点发光层之间设置由硫化物制备的界面层，所述界面层的HOMO能级大于所述空穴传输层的HOMO能级且小于所述量子点发光层的HOMO能级，所述界面层可以有效降低空穴的注入势垒，从而减少由于空穴在势垒界面处积累造成的材料及器件衰退，从而有效提高量子点发光二极管的发光效率以及使用 寿命。本实施例中的HOMO能级大小是指HOMO能级的绝对值大小。也就是说，本实施例中所述界面层的HOMO能级绝对值大于所述空穴传输层的HOMO能级绝对值且小于所述量子点发光层的HOMO能级绝对值。
进一步地，由于电子传输材料与量子点发光层之间的能级势垒通常较小，电子注入较为容易发生，这导致部分电子容易隧穿至空穴传输层或空穴传输层与量子点发光层之间的界面，并与空穴在非量子点发光层区域发生复合，从而影响量子点发光二极管的整体发光效率。本实施例通过在所述空穴传输层和量子点发光层之间设置由硫化物组成的界面层，所述界面层材料为硫化物，所述硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种，所述硫化物具有可导离子和空穴，但不导电子的性能，因此，所述硫化物不仅能够有效帮助空穴注入，还能够有效防止电子隧穿至空穴传输层，避免器件在非发光区域发光，从而提高量子点发光二极管的整体发光效率。
进一步地，由于量子点发光二极管的空穴传输层采用的材料通常为有机材料，如PEDOT(聚噻吩)等，该类材料对水及氧气较为敏感，水、氧从封装胶中逐渐渗透会影响空穴注入及传输的稳定性，本实施例通过在所述空穴传输层和量子点发光层之间设置由硫化物组成的界面层可进一步有效阻隔水、氧渗透，从而提高器件的使用寿命。
在一些实施方式中，所述界面层的厚度为10-200nm，在该范围内，所述界面层既能够提高空穴的注入速率，又能够阻挡电子的隧穿。若所述界面层的厚度小于10nm，则其阻挡电子隧穿至空穴传输层效果较差；若所述界面层的厚度大于200nm，则增加了空穴的注入距离，影响空穴传输至量子点发光层的效率。
在一些实施方式中，所述界面层的HOMO能级为4.9-6.0eV。本实施例中，由于空穴传输层的HOMO能级通常为4.9-5.4eV，量子点发光层的HOMO能级通常为5.9-6.5eV，此时界面层的HOMO能级位于所述空穴传输层和量子点发光层的HOMO能级之间，因此能够有效降低空穴的注入势垒，促进空穴的注入速率，从而减少由于空穴在势垒界面处积累造成的材料及器件衰退，从而有效提高量子点发光二极管 的发光效率以及使用寿命。作为举例，所述当采用TFB(HOMO能级为5.4eV)作为空穴传输层材料，采用Cds-ZnSe量子点(HOMO能级为5.9-6.1eV)作为量子点发光层材料时，此时所述界面层的HOMO能级可以为5.4-6eV。
在一些实施方式中，所述界面层材料为Li 3PS 4。在本实施例中，所述Li 3PS 4的HOMO能级位于所述空穴传输层和量子点发光层的HOMO能级之间，因此该界面层能够有效降低空穴的注入势垒，促进空穴的注入速率，从而减少由于空穴在势垒界面处积累造成的材料及器件衰退，从而有效提高量子点发光二极管的发光效率以及使用寿命。
在一些实施方式中，所述空穴传输层材料选自聚(9,9-二辛基芴-CO-N-(4-丁基苯基)二苯胺)(TFB)、聚乙烯咔唑(PVK)、聚(N,N'双(4-丁基苯基)-N,N'-双(苯基)联苯胺)(Poly-TPD)、聚(9,9-二辛基芴-共-双-N,N-苯基-1,4-苯二胺)(PFB)、4,4’,4”-三(咔唑-9-基)三苯胺(TCTA)、4,4'-二(9-咔唑)联苯(CBP)、N,N’-二苯基-N,N’-二(3-甲基苯基)-1,1’-联苯-4,4’-二胺(TPD)、N,N’-二苯基-N,N’-(1-萘基)-1,1’-联苯-4,4’-二胺(NPB)中的一种或多种，但不限于此。
在一些实施方式中，所述量子点发光层选自二元相量子点、三元相量子点和四元相量子点中的一种或多种，但不限于此。作为举例，所述所述二元相量子点为CdS、CdSe、CdTe、InP、AgS、PbS、PbSe、HgS中的至少一种；和/或，所述三元相量子点为Zn XCd 1-XS、Cu XIn 1-XS、Zn XCd 1-XSe、Zn XSe 1-XS、Zn XCd 1-XTe、PbSe XS 1-X中的至少一种；和/或，所述四元相量子点为Zn XCd 1-XS/ZnSe、Cu XIn 1-XS/ZnS、Zn XCd 1-XSe/ZnS、CuInSeS、Zn XCd 1-XTe/ZnS、PbSe XS 1-X/ZnS中的至少一种，其中0<X<1。
在一些实施方式中，所述量子点发光层与所述阴极之间设置有电子功能层，所述电子功能层包括空穴阻挡层、电子注入层和电子传输层，但不限于此。
在一些还是方式中，所述阳极和空穴传输层之间还设置有空穴注入层。
在一些实施方式中，所述空穴注入层为PEDOT:PSS、WO 3、MoO 3和V 2O 5中的一种或多种，但不限于此。
在一些实施方式中，所述，空穴注入层的厚度为30-120nm。
在一些实施方式中，阴极可以为Au、Ag、Al、Cu、Mo或它们的合金，但不限于此。
在一些实施方式中，所述阳极的厚度为5-120nm。
在一些实施方式中，所述空穴传输层的厚度为30-120nm。
在一些实施方式中，所述量子点发光层的厚度为10-200nm。
在一些实施方式中，所述电子传输层的厚度为5-100nm；所述阴极的厚度为5-120nm。
在一些实施方式中，所述阳极为ITO、FTO、ATO、AZO、GZO、IZO、MZO、AMO中的一种或多种，但不限于此。
在一些实施方式中，本公开还提供一种反型结构的量子点发光二极管，如图2所示，所述反型结构的量子点发光二极管包括设置在衬底表面的阴极，设置在所述阴极表面的量子点发光层，设置在所述量子点发光层表面的界面层，设置在所述界面层表面的空穴传输层，设置在所述空穴传输层表面的阳极，其中，所述界面层材料为硫化物，所述硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种，所述界面层的HOMO能级大于所述空穴传输层的HOMO能级且小于所述量子点发光层的HOMO能级。
本实施例通过在所述空穴传输层和量子点发光层之间设置由硫化物制备的界面层，所述界面层的HOMO能级大于所述空穴传输层的HOMO能级且小于所述量子点发光层的HOMO能级，所述界面层可以有效降低空穴的注入势垒，从而减少由于空穴在势垒界面处积累造成的材料及器件衰退，从而有效提高量子点发光二极管的发光效率以及使用寿命。所述界面层材料为硫化物，所述硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种，所述硫化物具有可导离子和空穴，但不导电子的性能，所述硫化物在常温下的空穴和离子电导率接近10 -2S/cm，其电子电导率小于所述离子/空穴电导率4-5个数量级以上，因此，所述硫化物不仅能够有效帮助空穴注入，还能够有效防止电子隧穿至空穴传输层，避免器件在非发光区域发光，从而提高量子点发光二极管的整体发光效率。
在一些实施方式中，还提供一种如图1所示正型结构的量子点发光二极管的制备方法，如图3所示，其包括步骤：
S10、提供一种阳极基板，在所述阳极基板上空穴传输层；
S20、在所述空穴传输层上制备界面层，所述界面层材料为硫化物，所述硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种；
S30、在所述界面层制备量子点发光层；
S40、在所述量子点发光层制备阴极，制得所述量子点发光二极管。
本实施例中，上述各层的制备方法可以是化学法或物理法，其中化学法包括但不限于化学气相沉积法、连续离子层吸附与反应法、阳极氧化法、电解沉积法、共沉淀法中的一种或多种；物理法包括但不限于物理镀膜法或溶液法，其中溶液法包括但不限于旋涂法、印刷法、刮涂法、浸渍提拉法、浸泡法、喷涂法、滚涂法、浇铸法、狭缝式涂布法、条状涂布法；物理镀膜法包括但不限于热蒸发镀膜法、电子束蒸发镀膜法、磁控溅射法、多弧离子镀膜法、物理气相沉积法、原子层沉积法、脉冲激光沉积法中的一种或多种。
在一些实施方式中，采用旋涂的方法在所述空穴传输层上制备界面层，其包括步骤：将所述硫化物分散在有机溶剂中，制得硫化物物溶液；将所述硫化物溶液旋涂在所述空穴传输层表面，在100℃下热退火30分钟制得界面层。在本实施例中，所述有机溶剂包括乙醇，甲醇，丁醇，丙酮，异丙酮，丁腈，氯苯，甲苯，二甲苯，二甲基甲酰胺，二甲基亚砜，N-甲基吡咯烷酮以及乙酸乙酯等，但不限于此。本实施例中，所述硫化物溶液的浓度为1-2wt％，在该浓度范围内，制备的界面层既可降低界面阻抗，又可有效提高量子点发光二极管的发光性能。
在一些实施方式中，还提供一种反型结构的量子点发光二极管的制备方法，其包括步骤：本公开还提供一种如图2所示反型结构的QLED的制备方法，如图4所示，其包括如下步骤：
S100、提供一种阴极基板，在所述阴极基板上制备量子点发光层；
S200、在所述量子点发光层表面制备界面层，所述界面层材料为硫化物，所述 硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种；
S300、在所述界面层上制备空穴传输层；
S400、在所述空穴传输层上制备阳极，制得所述量子点发光二极管。
在本公开的一种实施方式中，所述阴极基板包括衬底、设置在衬底上的底电极，所述底电极为阴极；在本公开的又一种实施方式中，所述阴极基板可以包括衬底、层叠设置在衬底表面的底电极和层叠设置在衬底表面的电子注入层；在本公开的又一种实施方式中，所述阴极基板可以包括衬底、层叠设置在衬底表面的底电极、层叠设置在衬底表面的电子注入层和层叠设置在电子注入层表面的电子传输层；在本公开的还一种实施方式中，所述阳极基板可以包括衬底、层叠设置在衬底表面的底电极、层叠设置在衬底表面的电子注入层、层叠设置在电子注入层表面的电子传输层和层叠设置在电子传输层表面的空穴阻挡层。
上述各层的制备方法可以是化学法或物理法，其中化学法包括但不限于化学气相沉积法、连续离子层吸附与反应法、阳极氧化法、电解沉积法、共沉淀法中的一种或多种；物理法包括但不限于物理镀膜法或溶液法，其中溶液法包括但不限于旋涂法、印刷法、刮涂法、浸渍提拉法、浸泡法、喷涂法、滚涂法、浇铸法、狭缝式涂布法、条状涂布法；物理镀膜法包括但不限于热蒸发镀膜法、电子束蒸发镀膜法、磁控溅射法、多弧离子镀膜法、物理气相沉积法、原子层沉积法、脉冲激光沉积法中的一种或多种。
下面通过实施例对本公开一种量子点发光二极管及其制备方法做进一步的解释说明：
本公开的实施例1提供了一种正置底发射结构的量子点发光二极管的制备方法，其包括以下步骤：
步骤S1：在透明阳极衬底上，沉积空穴注入层，所述透明阳极为ITO,所述空穴注入层材料为WO 3，所述透明阳极的厚度为20nm，空穴注入层的厚度为60nm；
步骤S2：在空穴注入层上，沉积空穴传输层，所述空穴传输层材料为PFB，所述空穴传输层的厚度为60nm；
步骤S3：在空穴传输层上，沉积界面层，所述界面层材料为Li 3PS 4,所述界面层的厚度为100nm；
步骤S4：在界面层上沉积量子点发光层，所述量子点发光层材料为PbSe，所述量子点发光层的厚度为50nm；
步骤S5：在量子点发光层上，沉积电子传输层，所述电子传输层材料为TiO，所述电子传输层的厚度为60nm；
步骤S6：在电子传输层上沉积金属阴极，所述阴极材料为Ag，所述阴极的厚度为100nm，阴极对可见光反射不低于98％。
本公开的实施例2提供了一种正置顶发射结构的量子点发光二极管的制备方法，其包括以下步骤：
步骤S1：在透明阳极衬底上，沉积空穴注入层，所述透明阳极为FTO,所述空穴注入层材料为WO 3，所述透明阳极的厚度为20nm，空穴注入层的厚度为60nm；
步骤S2：在空穴注入层上，沉积空穴传输层，所述空穴传输层材料为TCTA，所述空穴传输层的厚度为60nm；
步骤S3：在空穴传输层上，沉积界面层，所述界面层材料为Li 3PS 4,所述界面层的厚度为100nm；
步骤S4：在界面层上沉积量子点发光层，所述量子点发光层材料为InP，所述量子点发光层的厚度为50nm；
步骤S5：在量子点发光层上，沉积电子传输层，所述电子传输层材料为NiO，所述电子传输层的厚度为60nm；
步骤S6：在电子传输层上沉积阴极，所述阴极材料为Ag，所述阴极的厚度为100nm，阴极对可见光的透射不低于90％。
本公开的实施例3提供了一种倒置底发射结构的量子点发光二极管的制备方法，其包括以下步骤：
步骤S1：在衬底上通过蒸镀的方式沉积一层Ag层，所述Ag层的厚度为5nm；
步骤S2：在Ag层上沉积电子传输层，所述电子传输层材料为SnO，所述电子 传输层的厚度为50nm；
步骤S3：在电子传输层上沉积量子点发光层，所述量子点发光层材料为CdSe，所述量子点发光层的厚度为50nm；
步骤S4：在量子点发光层上沉积界面层，所述界面层的材料为Li 3PS 4,所述界面层的厚度为80nm；
步骤S5：在界面层上沉积空穴传输层，所述空穴传输层材料为PVK，所述空穴传输层的厚度为80nm；
步骤S6：空穴传输层上沉积空穴注入层,所述空穴注入层材料为PEDOT:PSS，所述空穴注入层的厚度为60nm；
步骤S7：在空穴注入层上沉积阳极，所述阳极材料为ITO，所述阳极的厚度为120nm；所述阳极对可见光反射不低于98％。
本公开的实施例4提供了一种倒置顶发射结构的量子点发光二极管的制备方法，其包括以下步骤：
步骤S1：在衬底上通过蒸镀的方式沉积一层Ag层，所述Ag层的厚度为5nm；
步骤S2：在Ag层上沉积电子传输层，所述电子传输层材料为TiO，所述电子传输层的厚度为60nm；
步骤S3：在电子传输层上沉积量子点发光层，所述量子点发光层材料为CdTe，所述量子点发光层的厚度为50nm；
步骤S4：在量子点发光层上沉积界面层，所述界面层的材料为Li 3PS 4,所述界面层的厚度为80nm；
步骤S5:在界面层上，沉积空穴传输层，所述空穴传输层材料为PFB，所述空穴传输层的厚度为80nm；
步骤S6：在空穴传输层上，沉积空穴注入层,所述空穴注入层材料为MoO 3，所述空穴注入层的厚度为60nm；
步骤S7：在空穴注入层上沉积阳极，所述阳极材料为ITO，所述阳极的厚度为120nm；所述阳极可见光的透射不低于90％。
本公开还提供一对比例1，包括一种正置底发射结构的量子点发光二极管的制备方法，其包括以下步骤：
步骤S1：在透明阳极衬底上，沉积空穴注入层，所述透明阳极为ITO,所述空穴注入层材料为WO 3，所述透明阳极的厚度为20nm，空穴注入层的厚度为60nm；
步骤S2：在空穴注入层上，沉积空穴传输层，所述空穴传输层材料为PFB，所述空穴传输层的厚度为60nm；
步骤S3：在空穴传输层上沉积量子点发光层，所述量子点发光层材料为PbSe，所述量子点发光层的厚度为50nm；
步骤S4：在量子点发光层上，沉积电子传输层，所述电子传输层材料为TiO，所述电子传输层的厚度为60nm；
步骤S5：在电子传输层上沉积金属阴极，所述阴极材料为Ag，所述阴极的厚度为100nm，阴极对可见光反射不低于98％。
本公开还提供一对比例2，包括一种正置顶发射结构的量子点发光二极管的制备方法，其包括以下步骤：
步骤S1：在透明阳极衬底上，沉积空穴注入层，所述透明阳极为FTO,所述空穴注入层材料为WO 3，所述透明阳极的厚度为20nm，空穴注入层的厚度为60nm；
步骤S2：在空穴注入层上，沉积空穴传输层，所述空穴传输层材料为TCTA，所述空穴传输层的厚度为60nm；
步骤S3：在空穴传输层上沉积量子点发光层，所述量子点发光层材料为InP，所述量子点发光层的厚度为50nm；
步骤S4：在量子点发光层上，沉积电子传输层，所述电子传输层材料为NiO，所述电子传输层的厚度为60nm；
步骤S5：在电子传输层上沉积阴极，所述阴极材料为Ag，所述阴极的厚度为100nm，阴极对可见光的透射不低于90％。
本公开还提供一对比例3，包括一种倒置底发射结构的量子点发光二极管的制备方法，其包括以下步骤：
步骤S1：在衬底上通过蒸镀的方式沉积一层Ag层，所述Ag层的厚度为5nm；
步骤S2：在Ag层上沉积电子传输层，所述电子传输层材料为SnO，所述电子传输层的厚度为50nm；
步骤S3：在电子传输层上沉积量子点发光层，所述量子点发光层材料为CdSe，所述量子点发光层的厚度为50nm；
步骤S4：在量子点发光层上沉积空穴传输层，所述空穴传输层材料为PVK，所述空穴传输层的厚度为80nm；
步骤S5：空穴传输层上沉积空穴注入层,所述空穴注入层材料为PEDOT:PSS，所述空穴注入层的厚度为60nm；
步骤S6：在空穴注入层上沉积阳极，所述阳极材料为ITO，所述阳极的厚度为120nm；所述阳极对可见光反射不低于98％。
本公开还提供一对比例4，包括一种倒置顶发射结构的量子点发光二极管的制备方法，其包括以下步骤：
步骤S1：在衬底上通过蒸镀的方式沉积一层Ag层，所述Ag层的厚度为5nm；
步骤S2：在Ag层上沉积电子传输层，所述电子传输层材料为TiO，所述电子传输层的厚度为60nm；
步骤S3：在电子传输层上沉积量子点发光层，所述量子点发光层材料为CdTe，所述量子点发光层的厚度为50nm；
步骤S4：在量子点发光层上沉积空穴传输层，所述空穴传输层材料为PFB，所述空穴传输层的厚度为80nm；
步骤S5：在空穴传输层上沉积空穴注入层,所述空穴注入层材料为MoO 3，所述空穴注入层的厚度为60nm；
步骤S6：在空穴注入层上沉积阳极阳极，所述阳极材料为ITO，所述阳极的厚度为120nm；所述阳极可见光的透射不低于90％。
对实施例1-4以及对比例1-4中制备的量子点发光二极管的性能进行测试，得到的结果如表1所示：
表1量子点发光二极管的性能测试结果
  外量子效率-EQE(％) LT95(h)
实施例1 10.2 6.3
实施例2 16.3 5.0
实施例3 9.4 6.8
实施例4 16.9 5.8
对比例1 7.9 5.4
对比例2 14.6 3.9
对比例3 8.3 5.9
对比例4 15.8 4.1
对比表1数据可以看出，实施例1与对比例1的差别仅在于在空穴传输层和量子点发光层之间增加了由Li 3PS 4材料形成的界面层，其外量子效率由7.9％提升至10.2％，其使用寿命由5.4h提升至6.3h；实施例2与对比例2的差别仅在于在空穴传输层和量子点发光层之间增加了由Li 3PS 4材料形成的界面层，其外量子效率由14.6％提升至16.3％，其使用寿命由3.9h提升至5.0h；实施例3与对比例3的差别仅在于在空穴传输层和量子点发光层之间增加了由Li 3PS 4材料形成的界面层，其外量子效率由8.3％提升至9.4％，其使用寿命由5.9h提升至6.8h；实施例4与对比例4的差别仅在于在空穴传输层和量子点发光层之间增加了由Li 3PS 4材料形成的界面层，其外量子效率由15.8％提升至16.9％，其使用寿命由4.1h提升至5.8h。通过上述数据可以发现，通过在空穴传输层与所述量子点发光层之间设置有界面层能够有效提升量子点发光二极管的外量子效率以及使用寿命。
综上所述，本公开对量子点发光二极管器件优化，通过在空穴传输层和量子点发光层中加入界面层从而降低空穴注入势垒，提高空穴注入，避免空穴在界面处积累，同时有效减少隧穿到空穴传输层的电子在非量子点发光区复合，提高器件效率 和寿命，界面层也可以有效阻隔水、氧对于有机空穴注入、传输层的影响，提高器件稳定性。
应当理解的是，本公开的应用不限于上述的举例，对本领域普通技术人员来说，可以根据上述说明加以改进或变换，所有这些改进和变换都应属于本公开所附权利要求的保护范围。

Claims (17)

  1. 一种量子点发光二极管，其特征在于，包括阴极、阳极，设置在所述阴极和阳极之间的量子点发光层，以及设置在所述阳极和量子点发光层之间的空穴传输层，所述空穴传输层与所述量子点发光层之间设置有界面层，所述界面层材料为硫化物，所述硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种；所述界面层的HOMO能级大于所述空穴传输层的HOMO能级且小于所述量子点发光层的HOMO能级。
  2. 根据权利要求1所述的量子点发光二极管，其特征在于，所述界面层的厚度为10-200nm。
  3. 根据权利要求1所述的量子点发光二极管，其特征在于，所述界面层的HOMO能级为5.4-6.0eV。
  4. 根据权利要求1所述的量子点发光二极管，其特征在于，所述界面层材料为Li 3PS 4。
  5. 根据权利要求1-3任一所述的量子点发光二极管，其特征在于，所述空穴传输层材料选自TFB、PVK、Poly-TPD、PFB、TCTA、CBP、TPD和NPB中的一种或多种。
  6. 根据权利要求5所述的量子点发光二极管，其特征在于，所述空穴传输材料选自TFB。
  7. 根据权利要求1-3任一所述的量子点发光二极管，其特征在于，所述量子点发光层材料选自二元相量子点、三元相量子点和四元相量子点中的一种或多种。
  8. 根据权利要求7所述的量子点发光二极管，其特征在于，所述二元相量子点为CdS、CdSe、CdTe、InP、AgS、PbS、PbSe、HgS中的至少一种；和/或，所述三元相量子点为Zn XCd 1-XS、Cu XIn 1-XS、Zn XCd 1-XSe、Zn XSe 1-XS、Zn XCd 1-XTe、PbSe XS 1-X中的至少一种；和/或，所述四元相量子点为Zn XCd 1-XS/ZnSe、Cu XIn 1-XS/ZnS、Zn XCd 1-XSe/ZnS、CuInSeS、Zn XCd 1-XTe/ZnS、PbSe XS 1-X/ZnS中的至少一种，其中0<X<1。
  9. 根据权利要求1所述的量子点发光二极管，其特征在于，所述量子点发光层 与所述阴极之间设置有电子功能层；和/或，所述阳极与空穴传输层之间设置有空穴注入层。
  10. 根据权利要求9所述的量子点发光二极管，其特征在于，所述电子功能层包括空穴阻挡层、电子注入层和电子传输层。
  11. 根据权利要求9所述的量子点发光二极管，其特征在于，所述空穴注入层为PEDOT:PSS、WO 3、MoO 3和V 2O 5中的一种或多种。
  12. 根据权利要求1所述的量子点发光二极管，其特征在于，所述阳极的厚度为5-120nm；和/或，所述阴极的厚度为5-120nm；和/或，所述量子点发光层的厚度为10-200nm；和/或，所述空穴传输层的厚度为30-120nm。
  13. 根据权利要求1所述的量子点发光二极管，其特征在于，所述阴极为Au、Ag、Al、Cu、Mo中的一种或多种。
  14. 根据权利要求1所述的量子点发光二极管，其特征在于，所述阳极为ITO、FTO、ATO、AZO、GZO、IZO、MZO、AMO中的一种或多种。
  15. 一种量子点发光二极管的制备方法，其特征在于，包括步骤：
    提供一种阳极基板，在所述阳极基板上空穴传输层；
    在所述空穴传输层上制备界面层，所述界面层材料为硫化物，所述硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种；
    在所述界面层制备量子点发光层；
    在所述量子点发光层制备阴极，制得所述量子点发光二极管；
    或者，提供一种阴极基板，在所述阴极基板上制备量子点发光层；
    在所述量子点发光层表面制备界面层，所述界面层材料为硫化物，所述硫化物的结构通式为Li xB yS z，其中，B为P，Si，Ge和Sn中的一种或多种；
    在所述界面层制备空穴传输层；
    在所述空穴传输层上制备阳极，制得所述量子点发光二极管。
  16. 根据权利要求15所述量子点发光二极管的制备方法，其特征在于，所述在所述空穴传输层上制备界面层的步骤包括：
    将所述硫化物分散在有机溶剂中，制得硫化物溶液；
    在所述空穴传输层表面制备界面层，所述界面层材料为所述硫化物；
    或，所述在所述量子点发光层表面制备界面层的步骤包括：
    将所述硫化物分散在有机溶剂中，制得硫化物溶液；
    在所述量子点发光层表面制备界面层，所述界面层材料为所述硫化物。
  17. 根据权利要求16所述量子点发光二极管的制备方法，其特征在于，所述硫化物溶液的浓度为1-2wt％。
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