CN111384274A - Quantum dot light-emitting diode and preparation method thereof - Google Patents

Quantum dot light-emitting diode and preparation method thereof Download PDF

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CN111384274A
CN111384274A CN201811643094.9A CN201811643094A CN111384274A CN 111384274 A CN111384274 A CN 111384274A CN 201811643094 A CN201811643094 A CN 201811643094A CN 111384274 A CN111384274 A CN 111384274A
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quantum dot
layer
dot light
emitting
blocking material
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CN111384274B (en
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聂志文
杨一行
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TCL Corp
TCL Research America Inc
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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]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/40—Interrelation of parameters between multiple constituent active layers or sublayers, e.g. HOMO values in adjacent layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • 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]
    • H10K50/11—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]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H10K50/125—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light
    • H10K50/13—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light comprising stacked EL layers within one EL unit
    • H10K50/131—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light comprising stacked EL layers within one EL unit with spacer layers between the electroluminescent layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/18—Carrier blocking layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass

Abstract

The invention discloses a quantum dot light-emitting diode and a preparation method thereof, wherein the quantum dot light-emitting diode comprises a cathode, an anode and a light-emitting layer arranged between the cathode and the anode, the light-emitting layer comprises n quantum dot light-emitting layers which are arranged in a stacked mode, n-1 electronic blocking material layers are arranged between the two adjacent quantum dot light-emitting layers, and n is an integer greater than or equal to 2. According to the quantum dot light-emitting diode, the injection rate of electrons and holes can be effectively balanced through the arrangement of the light-emitting layer, so that the recombination efficiency of carriers in the quantum dot light-emitting layer is improved, and further, the light-emitting efficiency, the stability and the service life of the quantum dot light-emitting diode are improved.

Description

Quantum dot light-emitting diode and preparation method thereof
Technical Field
The invention relates to the field of quantum dots, in particular to a quantum dot light-emitting diode and a preparation method thereof.
Background
A quantum dot light emitting diode (QLED) is a typical sandwich structure, and is composed of an electrode, a functional layer, a light emitting layer, and the like. Under the excitation of an external voltage, current carriers enter the quantum dots from the functional layers through the electrodes at the two ends to be compounded to form excitons, and the compounded excitons release photons in a radiation transition mode, so that light is emitted. Because the colloidal quantum dots have the characteristics of high luminous efficiency, high color purity, wide color gamut, good stability and the like, the QLED not only inherits the excellent performances of the quantum dots, but also has the characteristics of self-luminescence, wide visual angle, flexibility and the like, shows great commercial application prospect, and becomes an important research direction in the fields of new generation and illumination display. Meanwhile, the quantum dots are prepared by a solution method, so that the quantum dots are very suitable for being prepared into printing ink, and then large-scale and large-area preparation is realized by printing, ink jetting and other modes. At present, through more than twenty years of research and development, the QLED device is rapidly developed, and remarkable results are obtained. Especially, in recent years, the regulation of the functional layer is changed into the regulation of the quantum dots, and the performance of the QLED device is greatly promoted by alloying the quantum dots and growing the thick shell layer.
At present, for the QLED device, how to synchronously improve the efficiency, lifetime and stability of the device remains a very challenging problem. Generally, semiconductor quantum dots generally have a deep HOMO energy level, and a large potential barrier exists when charges are transported in each functional layer, so that electron and hole injection of the device are unbalanced during operation. On the one hand, a high carrier injection barrier increases the operating voltage of the device; on the other hand, unbalanced charge injection can greatly reduce the recombination probability of carriers in the luminescent layer, and easily trigger the non-radiative transition of excitons, thereby affecting the luminescent efficiency and the service life of the device.
Accordingly, the prior art is yet to be improved and developed.
Disclosure of Invention
In view of the defects of the prior art, the present invention aims to provide a quantum dot light emitting diode and a preparation method thereof, and aims to solve the problem that the emission efficiency and the service life of the device are affected due to the reduction of recombination probability of carriers in a light emitting layer caused by the unbalanced carrier injection in the conventional QLED device.
The technical scheme of the invention is as follows:
the quantum dot light-emitting diode comprises a cathode, an anode and a light-emitting layer arranged between the cathode and the anode, wherein the light-emitting layer comprises n quantum dot light-emitting layers which are arranged in a stacked mode, an electronic blocking material layer is arranged between every two adjacent quantum dot light-emitting layers, the number of the electronic blocking material layer is n-1, and n is an integer greater than or equal to 2.
A preparation method of a quantum dot light-emitting diode comprises the following steps:
providing a substrate;
preparing a light-emitting layer on the substrate, wherein the light-emitting layer comprises n quantum dot light-emitting layers which are arranged in a stacked mode, an electronic blocking material layer is arranged between every two adjacent quantum dot light-emitting layers, the number of the electronic blocking material layers is n-1, and n is an integer larger than or equal to 2.
Has the advantages that: the quantum dot light-emitting diode provided by the invention comprises a light-emitting layer arranged between a cathode and an anode, wherein the light-emitting layer comprises n quantum dot light-emitting layers which are arranged in a laminated manner, an electronic blocking material layer is arranged between the two adjacent quantum dot light-emitting layers, and n is an integer which is more than or equal to 2. According to the quantum dot light-emitting diode, the injection rate of electrons and holes can be effectively balanced through the arrangement of the light-emitting layer, so that the recombination efficiency of carriers in the quantum dot light-emitting layer is improved, and further, the light-emitting efficiency, the stability and the service life of the quantum dot light-emitting diode are improved.
Drawings
Fig. 1 is a schematic structural diagram of a quantum dot light emitting diode according to a preferred embodiment of the invention.
Fig. 2 is a schematic diagram of an energy band structure of a quantum dot light emitting diode according to the present invention.
FIG. 3 is a flowchart illustrating a method for fabricating a quantum dot light emitting diode according to a preferred embodiment of the present invention.
Detailed Description
The invention provides a quantum dot light-emitting diode and a preparation method thereof, and the invention is further described in detail below in order to make the purpose, technical scheme and effect of the invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention provides a quantum dot light-emitting diode which comprises cathodes, anodes and light-emitting layers arranged between the cathodes, wherein the light-emitting layers comprise n quantum dot light-emitting layers which are arranged in a laminated mode, an electronic blocking material layer is arranged between two adjacent quantum dot light-emitting layers, the number of the electronic blocking material layer is n-1, and n is an integer larger than or equal to 2.
For the quantum dot light-emitting diode, in the process of transmitting electrons from the cathode to the quantum dot light-emitting layer, the deeper the LUMO energy level of the electrons in each transmission layer, the larger the potential barrier in electron transmission, and the higher the energy required for electron tunneling through the transmission layer, the slower the electron transmission rate is caused, because the LUMO energy level of the electron blocking material layer is usually greater than the LUMO energy level of the quantum dot light-emitting layer, the transmission rate of the electrons can be effectively reduced by arranging the electron blocking material layer between adjacent quantum dot light-emitting layers, so that the injection rates of the electrons and holes are balanced, the recombination efficiency of carriers in the quantum dot light-emitting layer is improved, and further, the light-emitting efficiency, the stability and the service life of the quantum dot light-emitting diode are improved.
In some embodiments, the material of the electron blocking material layer is selected from one or more of PVK, Poly-TPD, NPB, TCTA, TAPC, CBP, TFB, and DNA, but is not limited thereto.
In some embodiments, the material of the electron blocking material layer is selected from one or more of compound-doped PVK, Poly-TPD, NPB, TCTA, TAPC, CBP, TFB and DNA, and the compound is selected from Li-TFSI, NiO, CuSCN, MoO3、CuO、V2O5Or CuS, but not limited thereto.
In some embodiments, the HOMO energy level of the material in the electronic barrier material layer is-5.0 to-8.0 eV, and the LUMO energy level of the electronic barrier material layer is-2.0 to-5.0 eV.
In some embodiments, the present invention further provides a quantum dot light emitting diode with a positive type structure as shown in fig. 1, the quantum dot light emitting diode with a positive type structure includes a substrate 10, an anode 20, a hole transport layer 30, a light emitting layer, an electron transport layer 50, and a cathode 60, which are stacked from bottom to top, the light emitting layer includes n quantum dot light emitting layers 41 stacked, n-1 electron blocking material layers 42 are disposed between two adjacent quantum dot light emitting layers, n is an integer greater than or equal to 3, and in the n-1 electron blocking material layers, between two adjacent electron blocking material layers, a HOMO energy level and a LUMO energy level of an electron blocking material layer material close to the cathode are both greater than a HOMO energy level and a LUMO energy level of an electron blocking material layer material close to the anode.
The quantum dot light-emitting diode can effectively balance the injection rate of electrons and holes through the arrangement of the light-emitting layer, so that the recombination efficiency of carriers in the quantum dot light-emitting layer is improved, and the light-emitting efficiency, the stability and the service life of the quantum dot light-emitting diode are further improved. The mechanism for achieving the above effects is specifically as follows:
for a quantum dot light-emitting diode, in the process of transmitting electrons from a cathode to a quantum dot light-emitting layer, the deeper the LUMO energy level of the electrons in each transmission layer, the larger the potential barrier during electron transmission, and the higher the energy required for electron tunneling through the transmission layer, resulting in slower electron transmission rate; in the process of transmitting the holes from the anode to the quantum dot light-emitting layer, the deeper the HOMO energy level of the holes in each transmission layer, the larger the potential barrier during hole transmission, and the higher the energy required for hole tunneling through the transmission layer, which results in the slower hole transmission rate. In this embodiment, a light-emitting layer in the quantum dot light-emitting diode includes n quantum dot light-emitting layers stacked and an electron blocking material layer disposed between adjacent quantum dot light-emitting layers, and between two adjacent electron blocking material layers, a HOMO energy level and a LUMO energy level of an electron blocking material layer material close to a cathode are both greater than a HOMO energy level and a LUMO energy level of an electron blocking material layer material close to an anode. As shown in fig. 2, the LUMO energy levels of the electron blocking material layers are all greater than the LUMO energy level of the quantum dot light emitting layer, when electrons are transmitted from the cathode to each quantum dot light emitting layer, the electrons need to tunnel through the electron blocking material layer with the largest LUMO energy level, and at this time, the electron barrier to be overcome is the largest; then tunneling the electron blocking material layers with sequentially reduced LUMO energy levels to reach the corresponding quantum dot light emitting layers, wherein in the subsequent tunneling process, electrons still need to overcome the potential barrier with larger energy levels, and the transmission rate of the electrons in each electron blocking material layer shows a slowing trend; because the HOMO energy level of the electronic blocking material layer is smaller than that of the quantum dot light-emitting layer, when holes are transmitted to the quantum dot light-emitting layers from the anode and tunnel through the quantum dot light-emitting layer with the deepest HOMO energy level, the potential barrier to be overcome is the largest, and the accumulation quantity of the holes in the quantum dot light-emitting layer is relatively small; as the HOMO energy level of the electron blocking material layer in the quantum dot light emitting layer becomes deeper in a stepwise manner, the barrier to be overcome when the hole tunnels through the corresponding electron blocking material layer becomes smaller and smaller, and therefore, the transmission rate of the hole is accelerated along with the further transmission of the hole. According to the quantum dot light-emitting diode, the injection rate of electrons and holes can be effectively balanced through the arrangement of the light-emitting layer, so that the recombination efficiency of carriers in the quantum dot light-emitting layer is improved, and further, the light-emitting efficiency, the stability and the service life of the quantum dot light-emitting diode are improved.
In some embodiments, the number of layers of the quantum dot light emitting layer is 3 to 11, i.e., the number of layers of the electron blocking material is 2 to 10. Preferably, the number of the layers of the electron blocking material layer is 2-5.
In some embodiments, the thickness of each layer of electron blocking material is 2-5 nm.
In some embodiments, the HOMO energy level of the material of the electronic barrier material is-5.0 to-8.0 eV, and the LUMO energy level of the material of the electronic barrier material is-2.0 to-5.0 eV. In some specific embodiments, between two adjacent electron blocking material layers in the n-1 electron blocking material layers, the HOMO level and the LUMO level of the electron blocking material layer material close to the cathode are both greater than the HOMO level and the LUMO level of the electron blocking material layer material close to the anode, the difference between the HOMO levels of the adjacent electron blocking material layer materials is-0.1 to-0.5 eV, and the difference between the LUMO levels of the adjacent electron blocking material layer materials is-0.1 to-0.5 eV.
In some embodiments, the electron blocking material layer material is selected from one or more of PVK, Poly-TPD, NPB, TCTA, TAPC, CBP, TFB, and DNA, but is not limited thereto.
In some embodiments, the material of the electron blocking material layer is selected from one or more of compound-doped PVK, Poly-TPD, NPB, TCTA, TAPC, CBP, TFB and DNA, and the compound is selected from Li-TFSI, NiO, CuSCN, MoO3、CuO、V2O5Or CuS, but not limited thereto. The purpose of selecting the electron blocking material doped with the compound is mainly to adjust the HOMO and LUMO energy levels of the material of the electron blocking material layer and realize a stepped potential barrier between the step energy levels, so that the transmission rate of electrons and holes is adjusted, and the recombination efficiency of excitons is improved. By way of example, the material of the electron barrier material layer is selected from PVK: Li-TFSI, PVK: NiO, PVK: CuSCN, PVK: MoO3、PVK: CuO、PVK: V2O5、PVK: CuS、Poly-TPD、Poly-TPD: Li-TFSI，Poly-TPD:-NiO，Poly-TPD: CuSCN，Poly-TPD: MoO3、Poly-TPD: CuO、Poly-TPD: V2O5、Poly-TPD: CuS、NPB、NPB: Li-TFSI，NPB -TPD:-NiO，NPB -TPD: CuSCN，NPB:MoO3、NPB: CuO、NPB: V2O5、NPB: CuS、TCTA、TCTA: Li-TFSI，TCTA -TPD:-NiO，TCTA -TPD:CuSCN、TCTA: MoO3、TCTA: CuO、TCTA: V2O5、TCTA: CuS、TAPC、TAPC: Li-TFSI、TAPC -TPD:-NiO，TAPC -TPD: CuSCN，TAPC: MoO3、TAPC: CuO、TAPC: V2O5、TAPC: CuS、CBP、CBP: Li-TFSI，CBP -TPD:-NiO、CBP -TPD: CuSCN、CBP: MoO3、CBP: CuO、CBP: V2O5、CBP: CuS、TFB、TFB: Li-TFSI、TFB -TPD:-NiO、TFB -TPD: CuSCN、TFB: MoO3、TFB: CuO、TFB: V2O5And TFB CuS, but is not limited thereto.
In some embodiments, between two adjacent quantum dot light emitting layers, the thickness of the quantum dot light emitting layer near the cathode is greater than the thickness of the quantum dot light emitting layer near the cathode. When the light emitting layer in the quantum dot light emitting diode includes n quantum dot light emitting layers arranged in a stacked manner and n-1 electron blocking material layers arranged between adjacent quantum dot light emitting layers, the transmission rate of the holes transmitted from the anode to each quantum dot light emitting layer is gradually increased, and the transmission rate of the electrons transmitted from the cathode to each quantum dot light emitting layer is gradually decreased. In some specific embodiments, in the n quantum dot light emitting layers, the thickness of two adjacent quantum dot light emitting layers differs by 5-20 nm. In some more specific embodiments, the thickness of the quantum dot light emitting layer closest to the anode among the n quantum dot light emitting layers is 1 to 10nm, and the thickness of the quantum dot light emitting layer closest to the cathode is 10 to 40 nm.
In some embodiments, the quantum dot light emitting layer material is selected from one or more of group II-VI compounds, group III-V compounds, and group I-III-VI compounds, but is not limited thereto. By way of example, the II-VI compound is selected from CdSe, CdS, CdTe, ZnSe, ZnS, CdTe, ZnTe, CdZnS, CdZnSe, CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS; one or more of CdZnSeS, CdZnSeTe and CdZnSTe; the III-V compound is selected from one or more of InP, InAs, GaP, GaAs, GaSb, AlN, AlP, InAsP, InNP, InNSb, GaAlNP and InAlNP; the group I-III-VI compound is selected from CuInS2、CuInSe2And AgInS2One or more of (a).
In some embodiments, the anode material is selected from Li, Ca, Ba, LiF, CsN3、Cs2CO3One or more of CsF, Ag, Mo, Al, Cu, and Au, but not limited thereto. In some embodiments, the anode has a thickness of 20 to 150 nm.
In some embodiments, the hole transport layer material is selected from the group consisting of TFB, PVK, Poly-TBP, Poly-TPD, NPB, TCTA, TAPC, CBP, PEODT: PSS, MoO3、WoO3、NiO、CuO、V2O5And CuS, but notAnd is limited thereto. In some embodiments, the hole transport layer has a thickness of 30 to 100 nm.
In some embodiments, the electron transport layer material is selected from ZnO, TiO2、Alq3SnO, ZrO, AlZnO, ZnSnO, BCP, TAZ, PBD, TPBI, Bphen and CsCO3But is not limited thereto. In some embodiments, the electron transport layer has a thickness of 10 to 120 nm.
In some embodiments, the cathode material is selected from one of ITO, FTO, or ZTO. In some embodiments, the cathode has a thickness of 60 to 130 nm.
It should be noted that the quantum dot light emitting diode of the present invention may further include one or more of the following functional layers: a hole injection layer arranged between the anode and the hole transport layer, and an electron injection layer arranged between the cathode and the electron transport layer.
The embodiment of the invention also provides a preparation method of the quantum dot light-emitting diode, as shown in fig. 3, comprising the following steps:
s01, providing a substrate;
s02, preparing a light emitting layer on the substrate, wherein the light emitting layer comprises n quantum dot light emitting layers which are arranged in a stacked mode, an electronic blocking material layer is arranged between the two adjacent quantum dot light emitting layers, the number of the electronic blocking material layers is n-1, and n is an integer larger than or equal to 2.
In some embodiments, the substrate is an anode substrate, and in some embodiments of the present invention, the anode substrate may include a base, an anode stacked on a surface of the base; in still other embodiments of the present invention, the anode substrate may include a base, an anode stacked on a surface of the base, and a hole injection layer stacked on a surface of the anode; in still other embodiments of the present invention, the substrate may include a base, an anode stacked on a surface of the base, a hole transport layer stacked on a surface of the anode; in still other embodiments of the present invention, the substrate may include a base, an anode stacked on a surface of the base, a hole injection layer stacked on a surface of the anode, and a hole transport layer stacked on a surface of the hole injection layer. In still other embodiments of the present invention, the anode substrate may include a base, an anode stacked on a surface of the base, a hole injection layer stacked on a surface of the anode, a hole transport layer stacked on a surface of the hole injection layer, and an electron blocking layer stacked on a surface of the hole transport layer.
In some embodiments, the substrate is a cathode substrate, and in some embodiments of the present invention, the cathode substrate includes a base and a cathode stacked on a surface of the base; in some embodiments of the present invention, the second substrate includes a base, a cathode stacked on a surface of the base, and an electron injection layer stacked on a surface of the cathode. In some embodiments of the present invention, the second substrate includes a base, a cathode stacked on a surface of the base, an electron injection layer stacked on a surface of the cathode, and an electron transport layer stacked on a surface of the electron injection layer; in some embodiments of the present invention, the second substrate includes a base, a cathode stacked on a surface of the base, an electron injection layer stacked on a surface of the cathode, an electron transport layer stacked on a surface of the electron injection layer, and a hole blocking layer stacked on a surface of the electron transport layer.
The embodiment of the present invention further provides an example of a method for manufacturing a quantum dot light emitting diode with a formal structure as shown in fig. 1, which specifically includes the following steps:
providing a substrate, and forming an anode on the substrate;
preparing a hole transport layer on the anode;
preparing a quantum dot light-emitting layer on the hole transport layer, preparing an electronic barrier material layer on the quantum dot light-emitting layer, continuously preparing another quantum dot light-emitting layer on the electronic barrier material layer, and repeating the steps until the last nth quantum dot light-emitting layer is prepared on the last electronic barrier material layer according to a preset thickness to prepare the light-emitting layer;
preparing an electron transport layer on the light emitting layer;
preparing a cathode on the electron transport layer to obtain the quantum dot light-emitting diode;
and in the n-1 layers of electronic blocking material layers, the HOMO energy level and the LUMO energy level of the electronic blocking material layer material close to the cathode are both greater than the HOMO energy level and the LUMO energy level of the electronic blocking material layer material close to the anode between two adjacent layers of electronic blocking material layers.
In the present invention, the preparation method of each layer may be a chemical method or a physical method, wherein the chemical method includes, but is not limited to, one or more of a chemical vapor deposition method, a continuous ionic layer adsorption and reaction method, an anodic oxidation method, an electrolytic deposition method, and a coprecipitation method; the physical method includes, but is not limited to, one or more of solution method (such as spin coating, printing, knife coating, dip-coating, dipping, spraying, roll coating, casting, slit coating, or bar coating), evaporation method (such as thermal evaporation, electron beam evaporation, magnetron sputtering, or multi-arc ion plating), deposition method (such as physical vapor deposition, atomic layer deposition, pulsed laser deposition, etc.).
The present invention will be described in detail below with reference to examples.
Example 1
The quantum dot light-emitting diode sequentially comprises a substrate, an anode, a hole injection layer, a hole transmission layer, a light-emitting layer, an electron transmission layer and a cathode which are stacked, wherein the light-emitting layer comprises 6 quantum dot light-emitting layers which are stacked and an electron blocking material layer arranged between the adjacent quantum dot light-emitting layers, and the electron blocking material layer is made of PVK, PVK doped with 1.5wt.% of Li-TFSI, PVK doped with 3wt.% of Li-TFSI, PVK doped with 4.5wt.% of Li-TFSI and PVK doped with 6wt.% of Li-TFSI along the direction from the anode to the cathode; the anode is made of ITO and has the thickness of 100 nm; PSS, the thickness of the hole injection layer is 40 nm; the hole transport layer is made of TFB and is 80 nm thick; the quantum dot light-emitting layer is made of InP/ZnS, and the thickness of each layer is 16 nm; the thickness of each layer of the electronic blocking material layer is 4 nm; the electron transport layer is made of ZnO and has the thickness of 60 nm; the cathode is Al and has a thickness of 50 nm.
Example 2
The quantum dot light-emitting diode sequentially comprises a substrate, an anode, a hole injection layer, a hole transmission layer, a light-emitting layer, an electron transmission layer and a cathode which are stacked, wherein the light-emitting layer comprises 6 quantum dot light-emitting layers which are stacked and an electron blocking material layer arranged between the adjacent quantum dot light-emitting layers, and the electron blocking material layer comprises TFB, TFB doped with 1.5wt.% of Li-TFSI, TFB doped with 3wt.% of Li-TFSI, TFB doped with 4.5wt.% of Li-TFSI and TFB doped with 6wt.% of Li-TFSI along the direction from the anode to the cathode; the anode is made of ITO and has the thickness of 100 nm; PSS, the thickness of the hole injection layer is 40 nm; the hole transport layer is made of TFB and is 80 nm thick; the quantum dot light-emitting layer is made of InP/ZnS, and the thickness of each layer is 16 nm; the thickness of each layer of the electronic blocking material layer is 4 nm; the electron transport layer is made of ZnO and has the thickness of 60 nm; the cathode is Al and has a thickness of 50 nm.
Example 3
The utility model provides a quantum dot emitting diode, from supreme substrate, positive pole, hole injection layer, hole transport layer, luminescent layer, electron transport layer and the negative pole of including range upon range of setting in proper order down, the luminescent layer is including range upon range of 6 quantum dot luminescent layers that set up and the electron barrier material layer of setting between adjacent quantum dot luminescent layer, along positive pole to the direction of negative pole, the material of every layer of electron barrier material layer is TCTA in proper order, is doped with 1.5wt.% MoO3TCTA of (a) doped with 3wt.% MoO3TCTA, 4.5wt.% MoO3TCTA and 6wt.% MoO3TCTA of (2); the anode is made of ITO and has the thickness of 100 nm; PSS, the thickness of the hole injection layer is 40 nm; the hole transport layer is made of TFB and is 80 nm thick; the quantum dot light-emitting layer is made of InP/ZnS, and the thickness of each layer is 16 nm; the thickness of each layer of the electronic blocking material layer is 4 nm; the electron transport layer is made of ZnO and has the thickness of 60 nm; the cathode is Al and has a thickness of 50 nm.
Example 4
The quantum dot light-emitting diode sequentially comprises a substrate, an anode, a hole injection layer, a hole transmission layer, a light-emitting layer, an electron transmission layer and a cathode which are stacked, wherein the light-emitting layer comprises 6 quantum dot light-emitting layers which are stacked and an electron blocking material layer arranged between the adjacent quantum dot light-emitting layers, and the electron blocking material layer is made of PVK, PVK doped with 1.5wt.% of Li-TFSI, PVK doped with 3wt.% of Li-TFSI, PVK doped with 4.5wt.% of Li-TFSI and PVK doped with 6wt.% of Li-TFSI along the direction from the anode to the cathode; the anode is made of ITO and has the thickness of 100 nm; PSS, the thickness of the hole injection layer is 40 nm; the hole transport layer is made of TFB and is 80 nm thick; the quantum dot light-emitting layer is made of CdZnS/CdZnSe/ZnS, and the thickness of each layer is 16 nm; the thickness of each layer of the electronic blocking material layer is 4 nm; the electron transport layer is made of ZnO and has the thickness of 60 nm; the cathode is Al and has a thickness of 50 nm.
Example 5
The quantum dot light-emitting diode sequentially comprises a substrate, an anode, a hole injection layer, a hole transmission layer, a light-emitting layer, an electron transmission layer and a cathode which are stacked, wherein the light-emitting layer comprises 6 quantum dot light-emitting layers which are stacked and an electron blocking material layer arranged between the adjacent quantum dot light-emitting layers, and the electron blocking material layer comprises TFB, TFB doped with 1.5wt.% of Li-TFSI, TFB doped with 3wt.% of Li-TFSI, TFB doped with 4.5wt.% of Li-TFSI and TFB doped with 6wt.% of Li-TFSI along the direction from the anode to the cathode; the anode is made of ITO and has the thickness of 100 nm; PSS, the thickness of the hole injection layer is 40 nm; the hole transport layer is made of TFB and is 80 nm thick; the quantum dot light-emitting layer is made of CdZnS/CdZnSe/ZnS, and the thickness of each layer is 16 nm; the thickness of each layer of the electronic blocking material layer is 4 nm; the electron transport layer is made of ZnO and has the thickness of 60 nm; the cathode is Al and has a thickness of 50 nm.
Example 6
A quantum dot light-emitting diode comprises a substrate, an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer and a cathode which are arranged in a laminated manner from bottom to top in sequence,the luminescent layer comprises 6 quantum dot luminescent layers arranged in a stacked mode and an electronic blocking material layer arranged between the adjacent quantum dot luminescent layers, and along the direction from the anode to the cathode, the material of each electronic blocking material layer is TCTA and doped with 1.5wt.% of MoO3TCTA of (a) doped with 3wt.% MoO3TCTA, 4.5wt.% MoO3TCTA and 6wt.% MoO3TCTA of (2); the anode is made of ITO and has the thickness of 100 nm; PSS, the thickness of the hole injection layer is 40 nm; the hole transport layer is made of TFB and is 80 nm thick; the quantum dot light-emitting layer is made of CdZnS/CdZnSe/ZnS, and the thickness of each layer is 16 nm; the thickness of each layer of the electronic blocking material layer is 4 nm; the electron transport layer is made of ZnO and has the thickness of 60 nm; the cathode is Al and has a thickness of 50 nm.
In summary, the quantum dot light emitting diode provided by the present invention includes a light emitting layer disposed between a cathode and an anode, the light emitting layer includes n quantum dot light emitting layers disposed in a stacked manner, n-1 electron blocking material layers are disposed between two adjacent quantum dot light emitting layers, n is an integer greater than or equal to 3, and in the n-1 electron blocking material layers, between two adjacent electron blocking material layers, a HOMO energy level and a LUMO energy level of an electron blocking material layer material close to the cathode are both greater than a HOMO energy level and a LUMO energy level of an electron blocking material layer material close to the anode. The electron blocking material layer with the stepped energy level structure is beneficial to reducing a hole injection barrier, so that the transmission performance of holes is increased, and the electron blocking material layer with the stepped energy level structure is also beneficial to slowing down the transmission performance of electrons; that is to say, the quantum dot light-emitting diode can effectively balance the injection rate of electrons and holes through the arrangement of the light-emitting layer, so that the recombination efficiency of carriers in the quantum dot light-emitting layer is improved, and further, the light-emitting efficiency, the stability and the service life of the quantum dot light-emitting diode are improved.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims (12)

1. The quantum dot light-emitting diode comprises a cathode, an anode and a light-emitting layer arranged between the cathode and the anode, and is characterized in that the light-emitting layer comprises n quantum dot light-emitting layers which are arranged in a stacked mode, an electronic blocking material layer is arranged between every two adjacent quantum dot light-emitting layers, the number of the electronic blocking material layer is n-1, and n is an integer greater than or equal to 2.
2. The quantum dot light-emitting diode of claim 1, wherein the material of the electron blocking material layer is selected from one or more of PVK, Poly-TPD, NPB, TCTA, TAPC, CBP, TFB and DNA;
or the material of the electronic barrier material layer is selected from one or more of compound-doped PVK, Poly-TPD, NPB, TCTA, TAPC, CBP, TFB and DNA, and the compound is selected from Li-TFSI, NiO, CuSCN and MoO3、CuO、V2O5Or CuS.
3. The quantum dot light-emitting diode of claim 1, wherein the HOMO energy level of the electron blocking material layer is-5.0 to-8.0 eV, and the LUMO energy level of the electron blocking material layer is-2.0 to-5.0 eV.
4. The quantum dot light-emitting diode of claim 1, wherein n is an integer of 3 or more, and between two adjacent electron blocking material layers in the n-1 electron blocking material layer, the HOMO level and the LUMO level of the material in the electron blocking material layer near the cathode are both greater than the HOMO level and the LUMO level of the material in the electron blocking material layer near the anode.
5. The QD LED of claim 4 wherein n is 3 ≦ n ≦ 11.
6. The QOS according to claim 4, wherein the difference of HOMO energy levels of materials in adjacent electron blocking material layers is-0.1 to-0.5 eV, and the difference of LUMO energy levels of materials in adjacent electron blocking material layers is-0.1 to-0.5 eV.
7. The quantum dot light-emitting diode of claim 1, wherein between two adjacent quantum dot light-emitting layers in the n quantum dot light-emitting layers, the thickness of the quantum dot light-emitting layer close to the cathode is greater than that of the close quantum dot light-emitting layer.
8. The qd-led of claim 7, wherein the thickness difference between two adjacent qd-luminescent layers in the n qd-luminescent layers is 5-20 nm.
9. The qd-led of claim 7, wherein the thickness of the qd-luminescent layer closest to the anode is 1-10nm and the thickness of the qd-luminescent layer closest to the cathode is 10-40nm in the n qd-luminescent layers.
10. The qd-led of any one of claims 1 to 9, wherein each layer of the electron blocking material has a thickness of 2 nm to 5 nm.
11. The qd-led according to any one of claims 1 to 9, wherein an electron transport layer is disposed between said cathode and the qd-light emitting layer; and/or the presence of a gas in the gas,
and a hole transport layer is arranged between the anode and the quantum dot light-emitting layer.
12. A preparation method of a quantum dot light-emitting diode is characterized by comprising the following steps:
providing a substrate;
preparing a light-emitting layer on the substrate, wherein the light-emitting layer comprises n quantum dot light-emitting layers which are arranged in a stacked mode, an electronic blocking material layer is arranged between every two adjacent quantum dot light-emitting layers, the number of the electronic blocking material layers is n-1, and n is an integer larger than or equal to 2.
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