WO2021184984A1 - Core-shell quantum dot, quantum dot light-emitting diode, quantum dot composition, and display device - Google Patents

Core-shell quantum dot, quantum dot light-emitting diode, quantum dot composition, and display device Download PDF

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WO2021184984A1
WO2021184984A1 PCT/CN2021/074750 CN2021074750W WO2021184984A1 WO 2021184984 A1 WO2021184984 A1 WO 2021184984A1 CN 2021074750 W CN2021074750 W CN 2021074750W WO 2021184984 A1 WO2021184984 A1 WO 2021184984A1
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quantum dot
shell
core
shell layer
layer
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PCT/CN2021/074750
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French (fr)
Chinese (zh)
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胡保忠
毛雁宏
李光旭
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纳晶科技股份有限公司
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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
    • H10K50/115—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising active inorganic nanostructures, e.g. luminescent quantum dots
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • 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

Definitions

  • This application relates to quantum dot materials, in particular to core-shell quantum dots, quantum dot light-emitting diodes, quantum dot compositions, and display devices.
  • Quantum dot light-emitting diode As a strong competitor of organic light-emitting diode (OLED), has been a research hotspot in recent years.
  • the research group of Professor Xiaogang Peng of Zhejiang University inserted an ultra-thin PMMA insulating layer between the quantum dot light-emitting layer and the electron injection layer through the solution spin coating method to improve the balance of carrier injection and make the red light
  • the external quantum efficiency of QLED can reach more than 20.5%, the service life is more than 100,000 hours, and its performance has reached or even surpassed commercial OLED products.
  • blue QLEDs have always been the shortcomings of quantum dot light-emitting diodes, which seriously hinder the commercialization of QLEDs.
  • the blue quantum dots currently used in blue QLEDs are generally CdZnS/ZnS or CdZnSeS/ZnS or ZnCdSe/ZnS structures.
  • the Korean research group obtained a blue quantum dot with a particle size of 11.5 nm and a ZnS shell thickness of 2.6 nm through a 3h ZnS coating.
  • the external quantum efficiency of the blue QLED using this quantum dot reached 7.1%.
  • the outer layer of blue quantum dots is coated with a thicker ZnS shell, which results in a deeper highest occupied molecular orbital (HOMO) energy level of blue quantum dots, and a higher lowest unoccupied molecular orbital (LUMO) energy level, which is not conducive to current carrying.
  • HOMO highest occupied molecular orbital
  • LUMO lowest unoccupied molecular orbital
  • An object of the present application is to provide a core-shell quantum dot with carrier injection balance.
  • Another object of the present application is to provide a quantum dot light-emitting diode with a long service life.
  • a core-shell quantum dot comprising a quantum dot core and a first shell layer, a second shell layer, and a third shell layer that are sequentially coated on the quantum dot core from the inside to the outside,
  • the quantum dot core is CdZnSe
  • the first shell layer is CdZnSeS
  • the second shell layer is ZnSeS
  • the third shell layer is CdZnS.
  • first shell layer, the second shell layer and the third shell layer are all homogeneous shell layers.
  • the particle size of the quantum dot core is 3nm ⁇ 8nm
  • the thickness of the first shell layer is 0.5nm ⁇ 3nm
  • the thickness of the second shell layer is 0.5nm ⁇ 3nm
  • the thickness of the third shell layer is 0.5nm. nm ⁇ 3nm.
  • the fluorescence emission peak of the core-shell quantum dots is 470 nm to 480 nm, and the fluorescence half-peak width of the core-shell quantum dots is 12 nm to 18 nm.
  • the photoluminescence quantum efficiency of the aforementioned core-shell quantum dots is greater than or equal to 90%.
  • the HOMO of the quantum dot core is higher than the HOMO of the first shell, and the energy level difference between the two is greater than or equal to 0.3 eV; the energy level difference between the LUMO of the first shell and the LUMO of the quantum dot core is less than or equal to 0.2 eV;
  • the HOMO of the first shell layer is higher than the HOMO of the second shell layer, and the energy level difference between the two is greater than or equal to 0.2 eV;
  • the energy level difference between the LUMO of the second shell layer and the LUMO of the first shell layer is less than or equal to 0.1 eV;
  • the energy level difference between the HOMO of the third shell layer and the HOMO of the second shell layer is less than or equal to 0.1 eV;
  • the LUMO of the third shell layer is lower than the LUMO of the second shell layer, and the energy level difference between the two is greater than or equal to 0.2 eV.
  • the fluorescence emission peak of the aforementioned core-shell quantum dots is 440 nm to 480 nm.
  • a quantum dot light emitting diode which includes a quantum dot light emitting layer, and the quantum dot light emitting layer includes any of the aforementioned core-shell quantum dots.
  • the external quantum efficiency of the aforementioned quantum dot light-emitting diode is 12%-15%.
  • the T 50 of the quantum dot light-emitting diode is greater than or equal to 9600 h.
  • a quantum dot composition which includes any of the aforementioned core-shell quantum dots.
  • a display device which includes any of the foregoing core-shell quantum dots, or includes any of the foregoing quantum dot light-emitting diodes.
  • the beneficial effect of the present application is that the core-shell quantum dots provided in the present application realize the separation of the hole wave function and the electron wave function, so that the hole wave function is confined in the quantum dot core, and the electron wave
  • the function delocalizes to the third shell layer, while ensuring that the emission peak wavelength is within the range of blue light, the hole injection capability and electron injection capability of the core-shell quantum dots can be adjusted separately to balance the carrier injection.
  • FIG. 1 is a transmission electron microscope (TEM) image of the quantum dot in Example 1 of the application.
  • FIG. 2 is a TEM image of the quantum dot in Example 2 of the application.
  • FIG. 3 is a TEM image of the quantum dot in Example 3 of the application.
  • HOMO refers to the highest occupied orbital in the molecular orbital. The higher the HOMO of the quantum dot material, the easier it is for holes to be injected; the term “LUMO” refers to the lowest vacant orbital in the molecular orbital , The lower the LOMO of the quantum dot material, the easier it is for electrons to be injected.
  • the blue quantum dots in the prior art generally use ZnS as the outer shell layer.
  • the conduction band of ZnS is too high, which is not conducive to the smooth injection of electrons.
  • the valence band is too deep, which hinders the effective transmission of holes. Therefore, the energy level structure of the existing blue quantum dots and the hole transport layer and the energy band gap of the electron transport layer materials are relatively large, resulting in carrier injection difficulties and imbalance in the injection of electrons and holes, and finally quantum dot light-emitting diodes ( QLED) device life is also low.
  • QLED quantum dot light-emitting diodes
  • the inventor of the present application found that to increase the injection of holes, the valence band of the quantum dot shell needs to be as shallow as possible, and to increase the injection of electrons, the conduction band of the shell needs to be as low as possible, but the valence band and the conduction band are at the same time.
  • the direct result of moving closer to the middle is that the forbidden band width of the quantum dots becomes narrower, and the emission wavelength of the quantum dots is red-shifted, which makes it difficult to ensure that the emission wavelength of the quantum dots is in the blue range.
  • the present invention provides a core-shell quantum dot with a hole wave function and an electron wave function separated.
  • the second shell and the third shell, the quantum dot core is CdZnSe
  • the first shell is CdZnSeS
  • the second shell is ZnSeS
  • the third shell is CdZnS.
  • the core-shell quantum dots can obtain red, green, and blue quantum dots by adjusting the size of the quantum dot core, the element composition of the shell, and the thickness of the shell.
  • the quantum dot core of this application selects high HOMO CdZnSe, which is conducive to the injection of holes.
  • the HOMO energy levels of the first shell CdZnSeS and the second shell ZnSeS coated on the quantum dot core are both higher than the HOMO energy of the quantum dot core.
  • the first shell and the second shell can confine the hole wave function of the quantum dot, so that the hole wave function is mainly distributed in the quantum dot core; in addition, the LUMO of the first shell and the second shell
  • the energy level is not much different from the LUMO energy level of the quantum dot core, so the first shell and the second shell are basically not limited to the electronic wave function of the quantum dot.
  • the third shell layer located on the outermost side of the quantum dot core is selected from CdZnS with low LUMO energy level, which is conducive to the injection of electrons.
  • the coating of the third shell layer further delocalizes the electronic wave function of the quantum dot, making the electron wave function main Distributed in the third shell.
  • This application realizes the separation of the electron wave function and the hole wave function of the core-shell quantum dots. While ensuring that the fluorescence emission peak wavelength of the core-shell quantum dots is within the blue range, the hole injection capability of the core-shell quantum dots can be adjusted separately And electron injection ability, thereby effectively solving the problem of carrier injection imbalance, which is beneficial to improve the service life of blue QLED devices.
  • CdZnSe can be expressed as CdZn X Se (1-X) , where 0 ⁇ X ⁇ 1; CdZnSeS can be expressed as CdZn M Se N S (1-MN) , where 0 ⁇ M ⁇ 1, 0 ⁇ N ⁇ 1, and M +N ⁇ 1; ZnSeS can be expressed as ZnSe Y S (1-Y) , where 0 ⁇ Y ⁇ 1; CdZnS can be expressed as CdZn Z S (1-Z) , where 0 ⁇ Z ⁇ 1.
  • the preparation method of the above-mentioned core-shell quantum dots can refer to the prior art or be prepared according to the following method: the zinc salt, the first long-chain fatty acid, and the non-coordinating solvent are mixed and heated to obtain the long-chain fatty acid zinc precursor solution; Add the first selenium precursor solution and the first cadmium precursor solution to the precursor solution and heat the reaction, continue to add the second selenium precursor solution for the heating reaction to obtain a solution containing CdZnSe quantum dot cores; add the first short-chain fatty acid zinc , The second long-chain fatty acid is added to the solution containing the CdZnSe quantum dot core, the temperature is raised to a specific temperature, and then the second cadmium precursor solution, the third selenium precursor solution, and the first sulfur precursor solution are added for heating reaction to obtain Solution of CdZnSe/CdZnSeS quantum dots; add the second short-chain fatty acid zinc and the third long-chain fatty acid to the aforementioned solution containing C
  • the particle size of the quantum dot core is 3nm ⁇ 8nm
  • the thickness of the first shell layer is 0.5nm ⁇ 3nm
  • the thickness of the second shell layer is 0.5nm ⁇ 3nm
  • the thickness of the third shell layer is 0.5nm ⁇ 3nm.
  • the particle size of the quantum dot core or the thickness of each shell layer is obtained by TEM observation and further calculation, and belongs to the average value.
  • the particle size of the quantum dot core is 3nm ⁇ 4nm or 4nm ⁇ 5nm or 5nm ⁇ 6nm or 6nm ⁇ 7nm or 7nm ⁇ 8nm
  • the thickness of the first shell layer is 0.5nm ⁇ 1.5nm or 1.6nm ⁇ 3nm
  • the thickness of the second shell layer is 0.5nm ⁇ 1.5nm or 1.6nm ⁇ 3nm
  • the thickness of the third shell layer is 0.5nm ⁇ 1.5nm or 1.6nm ⁇ 3nm.
  • the shape of the quantum dot includes, but is not limited to, a sphere or a sphere-like body.
  • the first shell layer, the second shell layer, and the third shell layer are all homogeneous shell layers.
  • a homogeneous shell layer means that the chemical composition of all parts of the shell layer is basically the same, which can be inferred from the preparation method, such as covering the first shell layer, the second shell layer and the third shell layer.
  • the shell layer by slowly dropping or adding the reaction precursor at a uniform rate, it can be considered that a homogeneous shell layer is obtained.
  • the shell layer will form a gradual alloy combination, and the cadmium precursor, the selenium precursor and the sulfur precursor are slowly added to the zinc precursor by dropping to obtain a homogeneous shell layer.
  • the fluorescence emission peak wavelength of the core-shell quantum dots is 470 nm to 480 nm.
  • the fluorescence half-width of core-shell quantum dots is 12nm ⁇ 18nm.
  • the core-shell quantum dots of the present application can be applied to the blue wave band, and have performance advantages compared to electroluminescent blue quantum dots with other structures.
  • the fluorescence emission peak wavelength of the core-shell quantum dots is 440 nm to 480 nm.
  • the photoluminescence quantum efficiency of the core-shell quantum dots is greater than or equal to 90%, or greater than or equal to 96%, or greater than or equal to 99%.
  • the HOMO energy level of the quantum dot core is higher than the HOMO energy level of the first shell, and the energy level difference between the two is greater than or equal to 0.3 eV.
  • the HOMO energy level of the first shell layer is higher than the HOMO energy level of the second shell layer, and the energy level difference between the two is greater than or equal to 0.2 eV.
  • the difference between the HOMO energy levels of the first shell layer and the second shell layer and the HOMO energy level of the quantum dot core is relatively large, and the hole wave function can be effectively distributed in the quantum dot core.
  • the difference between the LUMO energy level of the first shell and the LUMO energy level of the quantum dot core is less than or equal to 0.2 eV, and the difference between the LUMO energy level of the second shell and the LUMO energy level of the first shell Less than or equal to 0.1eV.
  • the LUMO energy levels of the first shell and the second shell are close to the LUMO energy levels of the quantum dot core, so the first shell and the second shell are basically not limited to the electronic wave functions of the quantum dots.
  • the LUMO energy level of the first shell layer may be higher or lower than the LUMO energy level of the quantum dot core, and the LUMO energy level of the second shell layer may be higher or lower than the LUMO energy level of the first shell layer.
  • the difference between the HOMO energy level of the third shell layer and the HOMO energy level of the second shell layer is less than or equal to 0.1 eV. It can be understood that the HOMO energy level of the third shell layer may be higher or lower than the HOMO energy level of the second shell layer.
  • the LUMO energy level of the third shell layer is lower than the LUMO energy level of the second shell layer, and the energy level difference between the two is greater than or equal to 0.2 eV.
  • the LUMO energy level of the third shell is lower than that of the second shell, which can further delocalize the electronic wave function of the quantum dots, so that the electronic wave function is mainly distributed in the third shell.
  • the present application also provides a quantum dot light-emitting diode, which includes a quantum dot light-emitting layer, and the quantum dot light-emitting layer includes the aforementioned core-shell quantum dot in this application.
  • the quantum dot light-emitting diode can be a positive device or an inverted device, which is not limited in this application.
  • the external quantum efficiency of the quantum dot light-emitting diode is 12%-15%.
  • the T 50 of the quantum dot light-emitting diode is greater than or equal to 9600 h. In some embodiments, when the initial brightness of the quantum dot light-emitting diode is 1000 cd/m 2 , the quantum dot light-emitting diode has 16000h ⁇ T 50 ⁇ 20000h.
  • the present application also provides a quantum dot composition, which includes any of the aforementioned core-shell quantum dots.
  • the composition can be used for optical materials, color conversion materials, inks, coatings, tagging agents, luminescent materials, and the like.
  • the composition includes glue, polymer colloid, or solvent.
  • the composition is solid or liquid or semi-solid.
  • the host material may be present in the composition in an amount of about 80 to about 99.5 weight percent.
  • particularly useful host materials include, but are not limited to, polymers, oligomers, monomers, resins, adhesives, glasses, metal oxides, and other non-polymer materials.
  • This application also provides a display device, which includes the aforementioned core-shell quantum dots of this application, or the aforementioned quantum dot light-emitting diodes of this application.
  • the above-mentioned display device may be, but not limited to, a liquid crystal display device, an OLED display device, a QLED display device, and the like.
  • Second shell coating Under the protection of nitrogen atmosphere, add 3mmol zinc acetate and 6mmol oleic acid to the solution of step (2), then heat up to 180°C and purge nitrogen for 30min, heat up to 300°C, and start adding Se- dropwise.
  • S-TBP mixed solution (mixing 0.8mL of Se-TBP with a concentration of 1.5mmol/mL and 0.2mL of S-TBP with a concentration of 1.5mmol/mL), the dropping rate is 1mL/h; after the addition, the temperature is cooled to room temperature , Purified to obtain CdZnSe/CdZnSeS/ZnSeS quantum dots, and then dissolved in 20mL ODE for later use.
  • the third shell coating Take 5.0 mL of the CdZnSe/CdZnSeS/ZnSeS quantum dot solution from step (3), 10mmol zinc acetate, 25mmol oleic acid and 10g ODE and mix in a three-necked flask.
  • Example 1 Statistics of the average size of quantum dots by TEM (the same in the following examples), in Example 1, the particle size of the CdZnSe quantum dot core is 5.0nm, the thickness of the first shell of CdZnSeS is 1.5nm, and the thickness of the second shell of ZnSeS The thickness of the third shell of CdZnS is 0.5nm and 3.0nm.
  • step (2) First shell coating: Cool the solution of step (1) to room temperature, under the protection of nitrogen atmosphere, add 2mmol zinc acetate and 5mmol oleic acid, then heat up to 180°C and blow nitrogen for 30min, then heat up to 300°C, start Add dropwise the Cd-ODE-Se-S-TBP mixed solution (from 1.5 mL of cadmium oleate ODE solution with a concentration of 0.1 mmol/mL, 0.8 mL of Se-TBP with a concentration of 1 mmol/mL, and 0.2 mL with a concentration of 1 mmol/mL S-TBP mixing), the dripping rate is 2mL/h, after the dripping is completed, the temperature is reduced to room temperature.
  • Cd-ODE-Se-S-TBP mixed solution from 1.5 mL of cadmium oleate ODE solution with a concentration of 0.1 mmol/mL, 0.8 mL of Se-TBP with a concentration of 1
  • Second shell coating Under the protection of nitrogen atmosphere, add 4mmol zinc acetate and 8mmol oleic acid to the solution of step (2), then heat up to 180°C and purge nitrogen for 30min, heat up to 300°C, and start adding Se- S-TBP mixed solution (mixed with 1.5mL Se-TBP with a concentration of 2mmol/mL and 0.5mL S-TBP with a concentration of 2mmol/mL), the dropping rate is 2mL/h; after the addition, the temperature is reduced to room temperature for purification The CdZnSe/CdZnSeS/ZnSeS quantum dots were obtained, and then dissolved in 20 mL ODE for use.
  • the third shell coating Take 5.0 mL of the CdZnSe/CdZnSeS/ZnSeS quantum dot solution from step (3), 10mmol zinc acetate, 25mmol oleic acid and 10g ODE and mix in a three-necked flask.
  • the particle size of the CdZnSe quantum dot core is 3.0 nm
  • the thickness of the first shell layer of CdZnSeS is 0.5 nm
  • the thickness of the second shell layer of ZnSeS is 3.0 nm
  • the thickness of the third shell layer of CdZnS is 3.0 nm.
  • step (2) First shell coating: Cool the solution of step (1) to room temperature, under the protection of nitrogen atmosphere, add 2mmol zinc acetate and 5mmol oleic acid, then heat up to 180°C and blow nitrogen for 30min, then heat up to 300°C, start Add dropwise Cd-ODE-Se-S-TBP mixed solution (from 2mL of cadmium oleate ODE solution with a concentration of 0.1mmol/mL, 0.7mL of Se-TBP with a concentration of 2mmol/mL and 0.3mL of S with a concentration of 2mmol/mL -TBP mixing), the dripping rate is 3mL/h, after the dripping is completed, the temperature is reduced to room temperature.
  • Cd-ODE-Se-S-TBP mixed solution from 2mL of cadmium oleate ODE solution with a concentration of 0.1mmol/mL, 0.7mL of Se-TBP with a concentration of 2mmol/mL and 0.3m
  • Second shell coating Under the protection of nitrogen atmosphere, add 4mmol zinc acetate and 8mmol oleic acid to the solution of step (2), then heat up to 180°C and purge nitrogen for 30min, heat up to 300°C, and start adding Se- S-TBP mixed solution (mixing 1.0mL of Se-TBP with a concentration of 2mmol/mL and 1.0mL of S-TBP with a concentration of 2mmol/mL), the dropping rate is 2mL/h; after the addition, the temperature is reduced to room temperature for purification The CdZnSe/CdZnSeS/ZnSeS quantum dots were obtained, and then dissolved in 20 mL ODE for use.
  • the third shell coating Take 5.0 mL of the CdZnSe/CdZnSeS/ZnSeS quantum dot solution from step (3), 10mmol zinc acetate, 25mmol oleic acid and 10g ODE and mix in a three-necked flask.
  • the particle size of the CdZnSe quantum dot core is 8.0 nm
  • the thickness of the first shell layer of CdZnSeS is 1.0 nm
  • the thickness of the second shell layer of ZnSeS is 2.0 nm
  • the thickness of the third shell layer of CdZnS is 0.5 nm.
  • the first shell layer coating cool the solution of step (1) to room temperature, add 6mmol zinc acetate and 12mmol oleic acid under the protection of nitrogen atmosphere, then heat up to 180°C and blow nitrogen for 30min, then heat up to 300°C, start Add dropwise Cd-ODE-Se-S-TBP mixed solution (from 2.5 mL of cadmium oleate ODE solution with a concentration of 0.1 mmol/mL, 1.5 mL of Se-TBP with a concentration of 2 mmol/mL, and 1 mL of S with a concentration of 2 mmol/mL -TBP mixing), the dripping rate is 5mL/h, after the dripping is completed, the temperature is reduced to room temperature.
  • Cd-ODE-Se-S-TBP mixed solution from 2.5 mL of cadmium oleate ODE solution with a concentration of 0.1 mmol/mL, 1.5 mL of Se-TBP with a concentration of 2 mmol/
  • Second shell coating Under the protection of nitrogen atmosphere, add 3mmol zinc acetate and 6mmol oleic acid to the solution of step (2), then heat up to 180°C and vent nitrogen for 30min, heat up to 300°C, and start adding Se- dropwise.
  • S-TBP mixed solution (mixed with 0.2mL Se-TBP with a concentration of 1.5mmol/mL and 1.8mL S-TBP with a concentration of 1.5mmol/mL), the dropping rate is 1mL/h; after the addition, the temperature is cooled to room temperature , Purified to obtain CdZnSe/CdZnSeS/ZnSeS quantum dots, and then dissolved in 20mL ODE for later use.
  • the third shell coating Take 5.0 mL of the CdZnSe/CdZnSeS/ZnSeS quantum dot solution from step (3), 10mmol zinc acetate, 25mmol oleic acid and 10g ODE and mix in a three-necked flask.
  • Example 4 the particle size of the CdZnSe quantum dot core is 5.5 nm, the thickness of the first shell layer of CdZnSeS is 3.0 nm, the thickness of the second shell layer of ZnSeS is 1.0 nm, and the thickness of the third shell layer of CdZnS is 2.0 nm.
  • Second shell coating Under the protection of nitrogen atmosphere, add 4mmol zinc acetate and 8mmol oleic acid to the solution of step (2), then heat up to 180°C with nitrogen for 30min, heat up to 300°C, and inject Se-S- TBP mixed solution (mixing 1.0mL Se-TBP with a concentration of 2mmol/mL and 1.0mL S-TBP with a concentration of 2mmol/mL); react at 300°C for 30 minutes, cool to room temperature, and purify to obtain CdZnSe/CdZnSeS/ZnSeS quantum dots. Then dissolve in 20mL Spare in ODE.
  • the third shell coating Take 5.0 mL of the CdZnSe/CdZnSeS/ZnSeS quantum dot solution from step (3), 10mmol zinc acetate, 25mmol oleic acid and 10g ODE and mix in a three-necked flask.
  • Example 5 the particle size of the CdZnSe quantum dot core is 7.0 nm, the thickness of the CdZnSeS first shell layer is 1.0 nm, the thickness of the ZnSeS second shell layer is 2.0 nm, and the thickness of the CdZnS third shell layer is 1.0 nm.
  • step (2) First shell coating: Cool the solution of step (1) to room temperature, add 4mmol zinc acetate and 8mmol oleic acid under the protection of nitrogen atmosphere, then heat up to 180°C and blow nitrogen for 30min, then heat up to 300°C, start Drop the Se-S-TBP mixed solution (1mL of Se-TBP with a concentration of 2mmol/mL and 0.5mL of S-TBP with a concentration of 2mmol/mL) at a rate of 3mL/h. After the addition is complete, cool to room temperature , Purified to obtain CdZnSe/ZnSeS quantum dots, and then dissolved in 20mL ODE for later use.
  • Second shell coating Take 5.0 mL of the CdZnSe/ZnSeS quantum dot solution of step (2), 10 mmol zinc acetate, 25 mmol oleic acid and 10 g ODE and mix in a three-necked flask. Under nitrogen protection, heat up to 150°C for reaction 30min; The temperature is raised to 300°C, and 3mL of S-TBP solution with a concentration of 2mmol/mL is added dropwise at a rate of 3mL/h; after the reaction is completed, the temperature is lowered to room temperature, and CdZnSe/ZnSeS/ZnS quantum dots are purified.
  • the particle size of the CdZnSe quantum dot core is 5.5 nm
  • the thickness of the first shell layer of ZnSeS is 2.0 nm
  • the thickness of the second shell layer of ZnSeS is 3.0 nm.
  • the core-shell quantum dots prepared in Examples 1 to 5 and Comparative Example 1 were tested for their fluorescence emission peak (PL), fluorescence half-width (FWHM) and photoluminescence quantum efficiency (Qys). The test results are recorded in Table 1. During the test, a 450nm blue LED was used as the backlight source to excite the toluene solution of the core-shell quantum dots (purified) to emit light, and the emission spectrum of the core-shell quantum dots was tested with an instrument to obtain the fluorescence emission peak and the fluorescence half-width.
  • PL fluorescence emission peak
  • FWHM fluorescence half-width
  • Qys photoluminescence quantum efficiency
  • the core-shell quantum dots prepared in Examples 1 to 5 and Comparative Example 1 were used to prepare QLED devices, and then the emission peak (EL) and external quantum efficiency (EQE) of each QLED device were tested and the initial brightness of the device was 1000 cd. /m 2 The time when the brightness attenuates by 50% (T 50 ). The test results are recorded in Table 1.
  • the test method of external quantum efficiency is as follows: Keithley 2400 is used to measure the current density-voltage curve of quantum dot light-emitting devices, and the integrating sphere (FOIS-1) combined with Ocean Optics spectrometer (QE-pro) is used to measure the brightness of quantum dot light-emitting devices. According to the measured current density and brightness, the external quantum efficiency of the quantum dot light-emitting device is calculated.
  • the external quantum efficiency characterizes the ratio between the number of photons emitted by the light-emitting device and the number of electrons injected into the device in the observation direction, and is an important parameter characterizing the luminous efficiency of the light-emitting device. The higher the external quantum efficiency, the higher the luminous efficiency of the device.
  • the preparation method of the QLED device can refer to the following steps, the variable is only the material of the light-emitting layer, and other conditions are the same.
  • PEDOT:PSS poly-p-styrene sulfonic acid solution
  • step (4) the device obtained in step (4) is placed in a vacuum evaporation chamber, and the cathode silver electrode is evaporated with a thickness of 100 nm.
  • the core-shell quantum dot structure of Comparative Example 1 is CdZnSe/ZnSeS/ZnS
  • the structure of the core-shell quantum dots of Examples 1-5 is CdZnSe/CdZnSeS/ZnSeS/CdZnS. From the experimental data in Table 1, it can be seen that the photoluminescence quantum efficiency Qys of the core-shell quantum dots of Examples 1-5 is higher than that of the core-shell quantum dots of Comparative Example 1.
  • the core-shell quantum dots of Examples 1-5 The fluorescence half-width (FWHM) of the dots is narrower than that of the core-shell quantum dots of the comparative example, indicating that the structure of the core-shell quantum dots provided in this application is beneficial to improve the photoluminescence quantum efficiency of the core-shell quantum dots and reduce the core-shell quantum dots.
  • the fluorescence half-peak width of the dots, the QLED prepared by using the core-shell quantum dots of Examples 1-5 has higher external quantum dot efficiency and longer service life.
  • the shell layers of the core-shell quantum dots of Examples 1-4 are homogeneous shell layers (the reaction precursor is added dropwise when the shell layer is grown), and the shell layers of the core-shell quantum dots of Example 5 are Heterogeneous shell layer (the reaction precursor is added by one-time injection during shell growth). From the experimental data in Table 1, it can be seen that the external quantum efficiency of the QLED prepared with the core-shell quantum dots of Examples 1-4 Higher, the lifetime of the device is longer.

Abstract

Disclosed in the present application are a core-shell quantum dot, a quantum dot light-emitting diode, a quantum dot composition, and a display device. The core-shell quantum dot comprises a quantum dot core, and a first shell layer, a second shell layer and a third shell layer that are sequentially coated on the quantum dot core from the inside to the outside. The material of the quantum dot core is CdZnSe, the material of the first shell layer is CdZnSeS, the material of the second shell is ZnSeS, and the material of the third shell layer is CdZnS. The core-shell quantum dot provided in the present application implements the separation of a hole wave function and an electron wave function, so that the hole wave function is confined within the quantum dot core, and the electron wave function is delocalized to the third shell layer, so that the hole injection capability and the electron injection capability of the core-shell quantum dot may be separately adjusted when ensuring that the emission peak wavelength is within the range of blue light, thereby balancing the injection of carriers.

Description

核壳量子点、量子点发光二极管、量子点组合物、显示器件Core-shell quantum dots, quantum dot light-emitting diodes, quantum dot compositions, display devices 技术领域Technical field
本申请涉及量子点材料，尤其涉及核壳量子点、量子点发光二极管、量子点组合物、显示器件。This application relates to quantum dot materials, in particular to core-shell quantum dots, quantum dot light-emitting diodes, quantum dot compositions, and display devices.
背景技术Background technique
量子点发光二极管（QLED）作为有机发光二极管（OLED）的有力竞争者，是近年来的研究热点。红光QLED方面，浙江大学彭笑刚教授课题组通过溶液旋涂法，在量子点发光层和电子注入层之间***超薄的PMMA绝缘层，实现对载流子的注入平衡的改善，使得红光QLED的外量子效率可达到20.5%以上、使用寿命超过100000小时，其性能已经达到甚至超越了商用的OLED产品。绿光QLED方面，2012年韩国某课题组通过在CdSe@ZnS外包覆1.6nm厚度的ZnS层得到绿光量子点，将其用于绿光QLED时，外量子效率可达到12.6%；2017年韩国课题组通过在MoO x和量子点层之间***聚乙氧基乙烯亚胺层，把绿光QLED反型器件的外量子效率推高到15.6%；2016年河南大学李林松课题组，通过对ZnCdSe/ZnS量子点表面进行三齿的巯基配体交换，增加了量子点的载流子注入能力，使得绿光QLED的外量子效率达到了16.5% ；绿光QLED的寿命有文献报道超过100000小时（初始亮度100cd/m 2），即绿光QLED的亮度和寿命已经基本满足商业化要求。 Quantum dot light-emitting diode (QLED), as a strong competitor of organic light-emitting diode (OLED), has been a research hotspot in recent years. In terms of red light QLEDs, the research group of Professor Xiaogang Peng of Zhejiang University inserted an ultra-thin PMMA insulating layer between the quantum dot light-emitting layer and the electron injection layer through the solution spin coating method to improve the balance of carrier injection and make the red light The external quantum efficiency of QLED can reach more than 20.5%, the service life is more than 100,000 hours, and its performance has reached or even surpassed commercial OLED products. In terms of green light QLEDs, in 2012, a Korean research group obtained green light quantum dots by coating CdSe@ZnS with a 1.6nm thick ZnS layer. When used in green light QLEDs, the external quantum efficiency can reach 12.6%; in 2017, South Korea The research group pushed the external quantum efficiency of the green QLED inversion device to 15.6% by inserting a polyethoxyethyleneimine layer between the MoO x and the quantum dot layer; in 2016, the research group of Li Linsong of Henan University passed the investigation of ZnCdSe /ZnS quantum dots exchange tridentate sulfhydryl ligands on the surface, increasing the carrier injection capacity of the quantum dots, making the external quantum efficiency of the green QLED reach 16.5%; the lifetime of the green QLED has been reported in the literature to exceed 100,000 hours ( The initial brightness is 100cd/m 2 ), that is, the brightness and lifespan of the green QLED have basically met commercial requirements.
但是，蓝光QLED一直都是量子点发光二极管的短板，严重阻碍QLED的商业化进展。目前用于蓝光QLED的蓝光量子点一般是CdZnS/ZnS或CdZnSeS/ZnS或ZnCdSe/ZnS结构。2013年，韩国课题组通过长达3h的ZnS包覆，得到了粒径11.5nm、ZnS壳厚度为 2.6nm的蓝光量子点，应用该量子点的蓝光QLED的外量子效率达到7.1%。但是目前蓝光量子点外层包覆较厚的ZnS壳层，导致蓝光量子点的最高占据分子轨道（HOMO）能级较深，最低未占分子轨道（LUMO）能级较高，不利于载流子的有效注入，而且目前蓝光QLED器件寿命一般不超过1000小时，远远没有达到商业化的最低要求。However, blue QLEDs have always been the shortcomings of quantum dot light-emitting diodes, which seriously hinder the commercialization of QLEDs. The blue quantum dots currently used in blue QLEDs are generally CdZnS/ZnS or CdZnSeS/ZnS or ZnCdSe/ZnS structures. In 2013, the Korean research group obtained a blue quantum dot with a particle size of 11.5 nm and a ZnS shell thickness of 2.6 nm through a 3h ZnS coating. The external quantum efficiency of the blue QLED using this quantum dot reached 7.1%. However, at present, the outer layer of blue quantum dots is coated with a thicker ZnS shell, which results in a deeper highest occupied molecular orbital (HOMO) energy level of blue quantum dots, and a higher lowest unoccupied molecular orbital (LUMO) energy level, which is not conducive to current carrying. The effective injection of electrons, and the current life of blue QLED devices generally does not exceed 1,000 hours, which is far from reaching the minimum requirements for commercialization.
技术解决方案Technical solutions
本申请的一个目的在于提供一种载流子注入平衡的核壳量子点。An object of the present application is to provide a core-shell quantum dot with carrier injection balance.
本申请的另一个目的在于提供一种使用寿命长的量子点发光二极管。Another object of the present application is to provide a quantum dot light-emitting diode with a long service life.
根据本申请的一个方面，提供了一种核壳量子点，包括量子点核以及由内到外依次包覆在上述量子点核上的第一壳层、第二壳层和第三壳层，上述量子点核为CdZnSe，上述第一壳层为CdZnSeS，上述第二壳层为ZnSeS，上述第三壳层为CdZnS。According to one aspect of the present application, there is provided a core-shell quantum dot, comprising a quantum dot core and a first shell layer, a second shell layer, and a third shell layer that are sequentially coated on the quantum dot core from the inside to the outside, The quantum dot core is CdZnSe, the first shell layer is CdZnSeS, the second shell layer is ZnSeS, and the third shell layer is CdZnS.
进一步地，上述第一壳层、上述第二壳层和上述第三壳层均为均质的壳层。Further, the first shell layer, the second shell layer and the third shell layer are all homogeneous shell layers.
进一步地，上述量子点核的粒径为3nm~8nm，上述第一壳层的厚度为0.5nm~3nm，上述第二壳层的厚度为0.5nm~3nm，上述第三壳层的厚度为0.5nm~3nm。Further, the particle size of the quantum dot core is 3nm~8nm, the thickness of the first shell layer is 0.5nm~3nm, the thickness of the second shell layer is 0.5nm~3nm, and the thickness of the third shell layer is 0.5nm. nm~3nm.
进一步地，上述核壳量子点的荧光发射峰为470nm~480nm，上述核壳量子点的荧光半峰宽为12nm~18nm。Further, the fluorescence emission peak of the core-shell quantum dots is 470 nm to 480 nm, and the fluorescence half-peak width of the core-shell quantum dots is 12 nm to 18 nm.
进一步地，上述核壳量子点的光致荧光量子效率大于等于90%。Further, the photoluminescence quantum efficiency of the aforementioned core-shell quantum dots is greater than or equal to 90%.
进一步地，上述量子点核的HOMO高于上述第一壳层的HOMO，二者的能级差大于等于0.3eV；上述第一壳层的LUMO与上述量子点核的LUMO能级差小于等于0.2eV；上述第一壳层的HOMO高于上述第二壳层的HOMO，二者的能级差大于等于0.2eV；上述第二壳层的LUMO与上述第一壳层的LUMO的能级差小于等于0.1eV；上述第三壳层的HOMO与上述第二壳层的HOMO的能级差小于等于0.1 eV；上述第三壳层的LUMO比上述第二壳层的LUMO低，二者的能级差大于等于0.2eV。Further, the HOMO of the quantum dot core is higher than the HOMO of the first shell, and the energy level difference between the two is greater than or equal to 0.3 eV; the energy level difference between the LUMO of the first shell and the LUMO of the quantum dot core is less than or equal to 0.2 eV; The HOMO of the first shell layer is higher than the HOMO of the second shell layer, and the energy level difference between the two is greater than or equal to 0.2 eV; the energy level difference between the LUMO of the second shell layer and the LUMO of the first shell layer is less than or equal to 0.1 eV; The energy level difference between the HOMO of the third shell layer and the HOMO of the second shell layer is less than or equal to 0.1 eV; the LUMO of the third shell layer is lower than the LUMO of the second shell layer, and the energy level difference between the two is greater than or equal to 0.2 eV.
进一步地，上述核壳量子点的荧光发射峰为440nm~480nm。Further, the fluorescence emission peak of the aforementioned core-shell quantum dots is 440 nm to 480 nm.
根据本申请的另一个方面，提供了一种量子点发光二极管，包括量子点发光层，上述量子点发光层包括前述任一种核壳量子点。According to another aspect of the present application, there is provided a quantum dot light emitting diode, which includes a quantum dot light emitting layer, and the quantum dot light emitting layer includes any of the aforementioned core-shell quantum dots.
进一步地，上述量子点发光二极管的外量子效率为12%~15%。Further, the external quantum efficiency of the aforementioned quantum dot light-emitting diode is 12%-15%.
进一步地，当上述量子点发光二极管的初始亮度为1000cd/m 2时，上述量子点发光二极管的T 50大于等于9600h。 Further, when the initial brightness of the quantum dot light-emitting diode is 1000 cd/m 2 , the T 50 of the quantum dot light-emitting diode is greater than or equal to 9600 h.
根据本申请的另一个方面，提供了一种量子点组合物，该量子点组合物包括前述任一种核壳量子点。According to another aspect of the present application, there is provided a quantum dot composition, which includes any of the aforementioned core-shell quantum dots.
根据本申请的另一个方面，提供了一种显示器件，其包括前述任一种核壳量子点，或者包括前述任一种的量子点发光二极管。According to another aspect of the present application, a display device is provided, which includes any of the foregoing core-shell quantum dots, or includes any of the foregoing quantum dot light-emitting diodes.
与现有技术相比，本申请的有益效果在于：本申请提供的核壳量子点实现了空穴波函数与电子波函数的分离，使空穴波函数限域在量子点核中，电子波函数离域到第三壳层中，在保证发射峰波长在蓝光范围内的同时，可以分别调节核壳量子点的空穴注入能力和电子注入能力，从而平衡载流子的注入。Compared with the prior art, the beneficial effect of the present application is that the core-shell quantum dots provided in the present application realize the separation of the hole wave function and the electron wave function, so that the hole wave function is confined in the quantum dot core, and the electron wave The function delocalizes to the third shell layer, while ensuring that the emission peak wavelength is within the range of blue light, the hole injection capability and electron injection capability of the core-shell quantum dots can be adjusted separately to balance the carrier injection.
附图说明Description of the drawings
图1为本申请实施例1的量子点的透射电子显微镜（TEM）图。FIG. 1 is a transmission electron microscope (TEM) image of the quantum dot in Example 1 of the application.
图2为本申请实施例2的量子点的TEM图。FIG. 2 is a TEM image of the quantum dot in Example 2 of the application.
图3为本申请实施例3的量子点的TEM图。FIG. 3 is a TEM image of the quantum dot in Example 3 of the application.
本发明的实施方式Embodiments of the present invention
下面，结合具体实施方式，对本申请做进一步描述，需要说明的是，在不相冲突的前提下，以下描述的各实施例之间或各技术特征之间可以任意组合形成新的实施例。In the following, the application will be further described in combination with specific implementations. It should be noted that, provided that there is no conflict, the following embodiments or technical features can be combined to form new embodiments.
需要说明的是，本申请的说明书和权利要求书中的术语“第一”、“第二”等是用于区别类似的对象，而不必用于描述特定的顺序或先后次序。It should be noted that the terms "first" and "second" in the specification and claims of this application are used to distinguish similar objects, and not necessarily used to describe a specific sequence or sequence.
本申请的说明书和权利要求书中的术语“包括”和“具有”以及他们的任何变形，意图在于覆盖不排他的包含，例如，包含了一系列步骤或单元的过程、方法、***、产品或设备不必限于清楚地列出的那些步骤或单元，而是可包括没有清楚地列出的或对于这些过程、方法、产品或设备固有的其它步骤或单元。The terms "including" and "having" in the specification and claims of this application and any variations of them are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or process that includes a series of steps or units. The equipment is not necessarily limited to those clearly listed steps or units, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or equipment.
 本申请的说明书和权利要求书中，当一个元件如层、膜或区域被称作“在”另外的元件“上”时，其可直接在所述另外的元件上或者还可存在中间元件。In the specification and claims of this application, when an element such as a layer, film or region is referred to as being "on" another element, it may be directly on the other element or there may also be intermediate elements.
本申请的说明书和权利要求书中，术语“HOMO”是指分子轨道中的最高已占轨道，量子点材料的HOMO越高空穴越容易注入；术语“LUMO”是指分子轨道中的最低空轨道，量子点材料的LOMO越低电子越容易注入。In the specification and claims of this application, the term "HOMO" refers to the highest occupied orbital in the molecular orbital. The higher the HOMO of the quantum dot material, the easier it is for holes to be injected; the term "LUMO" refers to the lowest vacant orbital in the molecular orbital , The lower the LOMO of the quantum dot material, the easier it is for electrons to be injected.
现有技术中的蓝光量子点普遍采用ZnS作为外侧壳层，ZnS的导带过高，不利于电子顺利注入，同时其价带太深，阻碍了空穴的有效传输。因此现有的蓝光量子点的能级结构与空穴传输层以及电子传输层材料的能带隙较大，导致载流子注入困难、电子和空穴的注入不平衡，最终量子点发光二极管（QLED）器件的寿命也低。本申请发明人发现，要增加空穴的注入，需要量子点壳层的价带尽可能浅，而要增加电子的注入，则需要壳层的导带尽可能低，但是价带和导带同时向中间靠拢的直接结果就是量子点的禁带宽度变窄，量子点发射波长红移，这就很难保证量子点的发射波长在蓝光范围内。The blue quantum dots in the prior art generally use ZnS as the outer shell layer. The conduction band of ZnS is too high, which is not conducive to the smooth injection of electrons. At the same time, the valence band is too deep, which hinders the effective transmission of holes. Therefore, the energy level structure of the existing blue quantum dots and the hole transport layer and the energy band gap of the electron transport layer materials are relatively large, resulting in carrier injection difficulties and imbalance in the injection of electrons and holes, and finally quantum dot light-emitting diodes ( QLED) device life is also low. The inventor of the present application found that to increase the injection of holes, the valence band of the quantum dot shell needs to be as shallow as possible, and to increase the injection of electrons, the conduction band of the shell needs to be as low as possible, but the valence band and the conduction band are at the same time The direct result of moving closer to the middle is that the forbidden band width of the quantum dots becomes narrower, and the emission wavelength of the quantum dots is red-shifted, which makes it difficult to ensure that the emission wavelength of the quantum dots is in the blue range.
为解决以上问题，本发明提供一种空穴波函数与电子波函数分离的核壳量子点，其包括量子点核以及由内到外依次包覆在量子点核上的第一壳层、第二壳层和第三壳层，量子点核为CdZnSe，第一壳层为CdZnSeS，第二壳层为ZnSeS，第三壳层为CdZnS。基于量子点的波长可调性特点，该核壳量子点通过调节量子点核的尺寸、壳层的元素组成以及壳层的厚度，从而可以得到红、绿、蓝三色波段量子点。In order to solve the above problems, the present invention provides a core-shell quantum dot with a hole wave function and an electron wave function separated. The second shell and the third shell, the quantum dot core is CdZnSe, the first shell is CdZnSeS, the second shell is ZnSeS, and the third shell is CdZnS. Based on the wavelength tunability of quantum dots, the core-shell quantum dots can obtain red, green, and blue quantum dots by adjusting the size of the quantum dot core, the element composition of the shell, and the thickness of the shell.
本申请的量子点核选择高HOMO的CdZnSe，有利于空穴的注入，在量子点核外包覆的第一壳层CdZnSeS和第二壳层ZnSeS的HOMO能级均比量子点核的HOMO能级低，因此第一壳层和第二壳层能够限域量子点的空穴波函数，使空穴波函数主要分布在量子点核中；此外，第一壳层和第二壳层的LUMO能级与量子点核的LUMO能级相差不大，因此第一壳层和第二壳层基本不限域量子点的电子波函数。位于量子点核最外侧的第三壳层选自低LUMO能级的CdZnS，有利于电子的注入，第三壳层的包覆进一步使量子点的电子波函数发生离域，使电子波函数主要分布在第三壳层中。本申请实现了核壳量子点的电子波函数和空穴波函数的分离，在保证核壳量子点的荧光发射峰波长在蓝光范围内的同时，能够分别调节核壳量子点的空穴注入能力和电子注入能力，从而有效解决了载流子注入不平衡的问题，有利于提高蓝光QLED器件的使用寿命。The quantum dot core of this application selects high HOMO CdZnSe, which is conducive to the injection of holes. The HOMO energy levels of the first shell CdZnSeS and the second shell ZnSeS coated on the quantum dot core are both higher than the HOMO energy of the quantum dot core The first shell and the second shell can confine the hole wave function of the quantum dot, so that the hole wave function is mainly distributed in the quantum dot core; in addition, the LUMO of the first shell and the second shell The energy level is not much different from the LUMO energy level of the quantum dot core, so the first shell and the second shell are basically not limited to the electronic wave function of the quantum dot. The third shell layer located on the outermost side of the quantum dot core is selected from CdZnS with low LUMO energy level, which is conducive to the injection of electrons. The coating of the third shell layer further delocalizes the electronic wave function of the quantum dot, making the electron wave function main Distributed in the third shell. This application realizes the separation of the electron wave function and the hole wave function of the core-shell quantum dots. While ensuring that the fluorescence emission peak wavelength of the core-shell quantum dots is within the blue range, the hole injection capability of the core-shell quantum dots can be adjusted separately And electron injection ability, thereby effectively solving the problem of carrier injection imbalance, which is beneficial to improve the service life of blue QLED devices.
需要说明的是，上述核和壳层材料的化学式仅代表元素组合，其中的各元素比例可以根据实际需要进行调节。CdZnSe 可以表示为CdZn XSe (1-X)，其中0＜X＜1；CdZnSeS可以表示为CdZn MSe NS (1-M-N)，其中0＜M＜1，0＜N＜1，且M+N＜1；ZnSeS 可以表示为ZnSe YS (1-Y)，其中0＜Y＜1；CdZnS可以表示为CdZn ZS (1-Z)，其中0＜Z＜1。此外，量子点核和第一壳层可以没有明显界面，量子点核和第一壳层的接触处可以有一部分融合（或合金化）；第一壳层和第一壳层之间、第二壳层和第三壳层之间也可以没有明显界面，彼此的接触处可以有一部分融合（或合金化）。 It should be noted that the above-mentioned chemical formulas of the core and shell materials only represent element combinations, and the proportions of the elements can be adjusted according to actual needs. CdZnSe can be expressed as CdZn X Se (1-X) , where 0＜X＜1; CdZnSeS can be expressed as CdZn M Se N S (1-MN) , where 0＜M＜1, 0＜N＜1, and M +N<1; ZnSeS can be expressed as ZnSe Y S (1-Y) , where 0<Y<1; CdZnS can be expressed as CdZn Z S (1-Z) , where 0<Z<1. In addition, there may be no obvious interface between the quantum dot core and the first shell, and a part of the contact between the quantum dot core and the first shell may be fused (or alloyed); between the first shell and the first shell, the second There may also be no obvious interface between the shell layer and the third shell layer, and a part of the contact point may be fused (or alloyed).
上述核壳量子点的制备方法可以参考现有技术或者按照下述方法制备：将锌盐、第一长链脂肪酸、非配位溶剂混合加热得到长链脂肪酸锌前体溶液；向长链脂肪酸锌前体溶液中加入第一硒前体溶液和第一镉前体溶液并加热反应，继续加入第二硒前体溶液进行加热反应，得到含CdZnSe量子点核的溶液；加入第一短链脂肪酸锌、第二长链脂肪酸至前述含CdZnSe量子点核的溶液中，升温至特定温度后继续加入第二镉前体溶液、第三硒前体溶液、第一硫前体溶液进行加热反应，得到含CdZnSe/CdZnSeS量子点的溶液；加入第二短链脂肪酸锌、第三长链脂肪酸至前述含CdZnSe/CdZnSeS量子点的溶液中，升温至特定温度后继续加入第四硒前体溶液、第二硫前体溶液进行加热反应，得到含CdZnSe/CdZnSeS/ZnSeS量子点的溶液；加入第三短链脂肪酸锌、第四长链脂肪酸至前述含CdZnSe/CdZnSeS/ZnSeS量子点的溶液中，升温至特定温度后继续加入第三镉前体溶液、第三硫前体溶液进行加热反应，得到含CdZnSe/CdZnSeS/ZnSeS/CdZnS量子点的溶液。上述短链脂肪酸锌中C个数可以为2~6，上述长链脂肪酸中C个数可以为18~22，上述特定温度可以为280~310℃中的任一温度。The preparation method of the above-mentioned core-shell quantum dots can refer to the prior art or be prepared according to the following method: the zinc salt, the first long-chain fatty acid, and the non-coordinating solvent are mixed and heated to obtain the long-chain fatty acid zinc precursor solution; Add the first selenium precursor solution and the first cadmium precursor solution to the precursor solution and heat the reaction, continue to add the second selenium precursor solution for the heating reaction to obtain a solution containing CdZnSe quantum dot cores; add the first short-chain fatty acid zinc , The second long-chain fatty acid is added to the solution containing the CdZnSe quantum dot core, the temperature is raised to a specific temperature, and then the second cadmium precursor solution, the third selenium precursor solution, and the first sulfur precursor solution are added for heating reaction to obtain Solution of CdZnSe/CdZnSeS quantum dots; add the second short-chain fatty acid zinc and the third long-chain fatty acid to the aforementioned solution containing CdZnSe/CdZnSeS quantum dots, and then continue to add the fourth selenium precursor solution and the second sulfur after heating to a specific temperature The precursor solution undergoes heating reaction to obtain a solution containing CdZnSe/CdZnSeS/ZnSeS quantum dots; add the third short-chain fatty acid zinc and the fourth long-chain fatty acid to the aforementioned solution containing CdZnSe/CdZnSeS/ZnSeS quantum dots, and heat to a specific temperature Then continue to add the third cadmium precursor solution and the third sulfur precursor solution for heating reaction to obtain a solution containing CdZnSe/CdZnSeS/ZnSeS/CdZnS quantum dots. The number of C in the zinc short-chain fatty acid can be 2-6, the number of C in the long-chain fatty acid can be 18-22, and the specific temperature can be any temperature from 280 to 310°C.
在一些实施例中，量子点核的粒径为3nm~8nm，第一壳层的厚度为0.5nm~3nm，第二壳层的厚度为0.5nm~3nm，第三壳层的厚度为0.5nm~3nm。量子点核的粒径或各壳层厚度通过TEM观察并进一步计算得到，且属于平均值。In some embodiments, the particle size of the quantum dot core is 3nm~8nm, the thickness of the first shell layer is 0.5nm~3nm, the thickness of the second shell layer is 0.5nm~3nm, and the thickness of the third shell layer is 0.5nm ~3nm. The particle size of the quantum dot core or the thickness of each shell layer is obtained by TEM observation and further calculation, and belongs to the average value.
在一些实施例中，量子点核的粒径为3nm~4nm或4nm~5nm或5nm~6nm或6nm~7nm或7nm~8nm，第一壳层的厚度为0.5nm~1.5nm或1.6nm~3nm，第二壳层的厚度为0.5nm~1.5nm或1.6nm~3nm，第三壳层的厚度为0.5nm~1.5nm或1.6nm~3nm。In some embodiments, the particle size of the quantum dot core is 3nm~4nm or 4nm~5nm or 5nm~6nm or 6nm~7nm or 7nm~8nm, and the thickness of the first shell layer is 0.5nm~1.5nm or 1.6nm~3nm , The thickness of the second shell layer is 0.5nm~1.5nm or 1.6nm~3nm, and the thickness of the third shell layer is 0.5nm~1.5nm or 1.6nm~3nm.
在一些实施例中，量子点的形状包括但不限于球体或者类球体。In some embodiments, the shape of the quantum dot includes, but is not limited to, a sphere or a sphere-like body.
在一些实施例中，第一壳层、第二壳层、第三壳层均为均质的壳层。本领域的技术人员可以理解的是，均质的壳层是指壳层各处的化学组成基本一致，可以从制备方法进行推断，比如在包覆第一壳层、第二壳层以及第三壳层时，通过缓慢滴加或者匀速加入反应前体，可以认为制得的是均质的壳层。以第一壳层的CdZnSeS为例，由于镉前体、锌前体、硒前体与硫前体的反应活性各不相同，如果将硒前体与硫前体一次性注入镉前体与锌前体中，壳层会形成渐变的合金结合，而采用滴加的方式向锌前体中缓慢加入镉前体、硒前体与硫前体，则可以得到均质的壳层。In some embodiments, the first shell layer, the second shell layer, and the third shell layer are all homogeneous shell layers. Those skilled in the art can understand that a homogeneous shell layer means that the chemical composition of all parts of the shell layer is basically the same, which can be inferred from the preparation method, such as covering the first shell layer, the second shell layer and the third shell layer. In the case of the shell layer, by slowly dropping or adding the reaction precursor at a uniform rate, it can be considered that a homogeneous shell layer is obtained. Taking the CdZnSeS of the first shell layer as an example, since the reactivity of cadmium precursor, zinc precursor, selenium precursor and sulfur precursor are different, if the selenium precursor and sulfur precursor are injected into the cadmium precursor and zinc at one time In the precursor, the shell layer will form a gradual alloy combination, and the cadmium precursor, the selenium precursor and the sulfur precursor are slowly added to the zinc precursor by dropping to obtain a homogeneous shell layer.
在一些实施例中，核壳量子点的荧光发射峰波长为470nm~480nm。核壳量子点的荧光半峰宽为12nm~18nm。本申请的核壳量子点可以适用于蓝色波段，相比于其他结构的电致发光蓝色量子点更具性能优势。In some embodiments, the fluorescence emission peak wavelength of the core-shell quantum dots is 470 nm to 480 nm. The fluorescence half-width of core-shell quantum dots is 12nm~18nm. The core-shell quantum dots of the present application can be applied to the blue wave band, and have performance advantages compared to electroluminescent blue quantum dots with other structures.
在一些实施例中，核壳量子点的荧光发射峰波长为440nm~480nm。In some embodiments, the fluorescence emission peak wavelength of the core-shell quantum dots is 440 nm to 480 nm.
在一些实施例中，核壳量子点的光致荧光量子效率大于等于90%，或大于等于96%，或大于等于99%。In some embodiments, the photoluminescence quantum efficiency of the core-shell quantum dots is greater than or equal to 90%, or greater than or equal to 96%, or greater than or equal to 99%.
在一些实施例中，量子点核的HOMO能级高于第一壳层的HOMO能级，二者的能级差大于等于0.3eV。第一壳层的HOMO能级高于第二壳层的HOMO能级，二者的能级差大于等于0.2eV。第一壳层和第二壳层的HOMO能级与量子点核的HOMO能级的差值较大，可以有效使空穴波函数分布在量子点核内。In some embodiments, the HOMO energy level of the quantum dot core is higher than the HOMO energy level of the first shell, and the energy level difference between the two is greater than or equal to 0.3 eV. The HOMO energy level of the first shell layer is higher than the HOMO energy level of the second shell layer, and the energy level difference between the two is greater than or equal to 0.2 eV. The difference between the HOMO energy levels of the first shell layer and the second shell layer and the HOMO energy level of the quantum dot core is relatively large, and the hole wave function can be effectively distributed in the quantum dot core.
在一些实施例中，第一壳层的LUMO能级与量子点核的LUMO能级的差值小于等于0.2eV，第二壳层的LUMO能级与第一壳层的LUMO能级的差值小于等于0.1eV。第一壳层以及第二壳层的LUMO能级与量子点核的LUMO能级接近，因此第一壳层与第二壳层基本不限域量子点的电子波函数。可以理解的是，第一壳层的LUMO能级可以比量子点核的LUMO能级高或低，第二壳层的LUMO能级可以比第一壳层的LUMO能级高或低。In some embodiments, the difference between the LUMO energy level of the first shell and the LUMO energy level of the quantum dot core is less than or equal to 0.2 eV, and the difference between the LUMO energy level of the second shell and the LUMO energy level of the first shell Less than or equal to 0.1eV. The LUMO energy levels of the first shell and the second shell are close to the LUMO energy levels of the quantum dot core, so the first shell and the second shell are basically not limited to the electronic wave functions of the quantum dots. It is understandable that the LUMO energy level of the first shell layer may be higher or lower than the LUMO energy level of the quantum dot core, and the LUMO energy level of the second shell layer may be higher or lower than the LUMO energy level of the first shell layer.
在一些实施例中，第三壳层的HOMO能级与第二壳层的HOMO能级的差值小于等于0.1 eV。可以理解的是，第三壳层的HOMO能级可以比第二壳层的HOMO能级高或低。第三壳层的LUMO能级比第二壳层的LUMO能级低，二者的能级差大于等于0.2eV。第三壳层的LUMO能级低于第二壳层，能够进一步离域量子点的电子波函数，使电子波函数主要分布在第三壳层中。In some embodiments, the difference between the HOMO energy level of the third shell layer and the HOMO energy level of the second shell layer is less than or equal to 0.1 eV. It can be understood that the HOMO energy level of the third shell layer may be higher or lower than the HOMO energy level of the second shell layer. The LUMO energy level of the third shell layer is lower than the LUMO energy level of the second shell layer, and the energy level difference between the two is greater than or equal to 0.2 eV. The LUMO energy level of the third shell is lower than that of the second shell, which can further delocalize the electronic wave function of the quantum dots, so that the electronic wave function is mainly distributed in the third shell.
本申请还提供一种量子点发光二极管，包括量子点发光层，量子点发光层包括本申请前述的核壳量子点。量子点发光二极管可以为正型器件或反型器件，本申请对此不做限定。The present application also provides a quantum dot light-emitting diode, which includes a quantum dot light-emitting layer, and the quantum dot light-emitting layer includes the aforementioned core-shell quantum dot in this application. The quantum dot light-emitting diode can be a positive device or an inverted device, which is not limited in this application.
在一些实施例中，量子点发光二极管的外量子效率为12%~15%。In some embodiments, the external quantum efficiency of the quantum dot light-emitting diode is 12%-15%.
在一些实施例中，当量子点发光二极管的初始亮度为1000cd/m 2时，量子点发光二极管的T 50大于等于9600h。在一些实施例中，当量子点发光二极管的初始亮度为1000cd/m 2时，量子点发光二极管的16000h≤T 50≤20000h。 In some embodiments, when the initial brightness of the quantum dot light-emitting diode is 1000 cd/m 2 , the T 50 of the quantum dot light-emitting diode is greater than or equal to 9600 h. In some embodiments, when the initial brightness of the quantum dot light-emitting diode is 1000 cd/m 2 , the quantum dot light-emitting diode has 16000h≦T 50 ≦20000h.
本申请还提供了一种量子点组合物，该量子点组合物包括前述任一种核壳量子点。组合物可以用于光学材料、颜色转换材料、油墨、涂料、标签剂、发光材料等。The present application also provides a quantum dot composition, which includes any of the aforementioned core-shell quantum dots. The composition can be used for optical materials, color conversion materials, inks, coatings, tagging agents, luminescent materials, and the like.
在一些实施例中，组合物包括胶水、高分子胶体、或者溶剂。组合物为固态或液态或半固态。In some embodiments, the composition includes glue, polymer colloid, or solvent. The composition is solid or liquid or semi-solid.
在某些实施例中，组合物中主体材料的存在量可以为约80至约99.5重量百分比。具体有用的主体材料的实例包括但不限于聚合物、低聚物、单体、树脂、粘合剂、玻璃、金属氧化物、和其它非聚合物材料。In certain embodiments, the host material may be present in the composition in an amount of about 80 to about 99.5 weight percent. Examples of particularly useful host materials include, but are not limited to, polymers, oligomers, monomers, resins, adhesives, glasses, metal oxides, and other non-polymer materials.
本申请还提供了一种显示器件，包括本申请前述的核壳量子点，或者包括本申请前述的量子点发光二极管。上述显示器件可以是但不限于液晶显示装置、OLED显示装置、QLED显示装置等。This application also provides a display device, which includes the aforementioned core-shell quantum dots of this application, or the aforementioned quantum dot light-emitting diodes of this application. The above-mentioned display device may be, but not limited to, a liquid crystal display device, an OLED display device, a QLED display device, and the like.
实施例1Example 1
（1）量子点核制备：取4mmol碱式碳酸锌、4.0mL油酸、15g十八烯加入三口烧瓶，氮气氛围保护下，升温至280℃ 形成澄清透明的溶液；然后向三口烧瓶中依次注入2.0mL浓度为0.5mmol/mL的Se-ODE悬浮液和1.0mL浓度为0.2mmol/mL的油酸镉ODE溶液，升温至300℃，补加1.0mL浓度为 2mmol/mL的Se-TBP溶液，继续升温至310℃ 反应90min。(1) Preparation of quantum dot core: Take 4mmol basic zinc carbonate, 4.0mL oleic acid, and 15g octadecene into a three-necked flask. Under the protection of nitrogen atmosphere, heat up to 280℃ to form a clear and transparent solution; then inject into the three-necked flask one by one 2.0mL Se-ODE suspension with a concentration of 0.5mmol/mL and 1.0mL cadmium oleate ODE solution with a concentration of 0.2mmol/mL, warm up to 300°C, add 1.0mL of Se-TBP solution with a concentration of 2mmol/mL, Continue to heat up to 310°C and react for 90 minutes.
（2）第一壳层包覆：将步骤（1）的溶液降温到室温，氮气氛围保护下，加入3mmol醋酸锌和7.5 mmol 油酸，然后升温到180℃通氮气30min，升温到300℃，开始滴加Cd-ODE-Se-S-TBP混合溶液（由1.0mL浓度为0.1mmol/mL的油酸镉ODE溶液、0.9mL浓度为2mmol/mL的Se-TBP以及0.1mL浓度为2mmol/mL的S-TBP混合），滴加速度为2mL/h，滴加完毕后，降温到室温。(2) Coating of the first shell layer: Cool the solution of step (1) to room temperature, under the protection of nitrogen atmosphere, add 3mmol zinc acetate and 7.5 mmol oleic acid, then heat to 180°C and bubbling nitrogen for 30 minutes, then heat to 300°C, and start to add dropwise Cd-ODE-Se-S-TBP mixed solution (from 1.0mL cadmium oleate ODE solution with a concentration of 0.1mmol/mL, 0.9 mL of Se-TBP with a concentration of 2mmol/mL and 0.1mL of S-TBP with a concentration of 2mmol/mL), the dropping rate is 2mL/h, after the addition, the temperature is cooled to room temperature.
（3）第二壳层包覆：氮气氛围保护下，向步骤（2）的溶液加入3mmol醋酸锌和6mmol 油酸，然后升温到180℃通氮气30min，升温到300℃，开始滴加Se-S-TBP混合溶液（由0.8mL 浓度为1.5mmol/mL的Se-TBP与0.2mL浓度为1.5mmol/mL的S-TBP混合），滴加速度为1mL/h；滴加完毕后，降温到室温，提纯得到CdZnSe/CdZnSeS/ZnSeS量子点，然后溶于20mL ODE中备用。(3) Second shell coating: Under the protection of nitrogen atmosphere, add 3mmol zinc acetate and 6mmol oleic acid to the solution of step (2), then heat up to 180°C and purge nitrogen for 30min, heat up to 300°C, and start adding Se- dropwise. S-TBP mixed solution (mixing 0.8mL of Se-TBP with a concentration of 1.5mmol/mL and 0.2mL of S-TBP with a concentration of 1.5mmol/mL), the dropping rate is 1mL/h; after the addition, the temperature is cooled to room temperature , Purified to obtain CdZnSe/CdZnSeS/ZnSeS quantum dots, and then dissolved in 20mL ODE for later use.
（4）第三壳层包覆：取5.0mL步骤（3）的CdZnSe/CdZnSeS/ZnSeS量子点溶液、10mmol乙酸锌、25mmol油酸和10g ODE于三口烧瓶中混合，氮气保护下，升温到150℃反应30min；升温到300℃，开始滴加Cd-ODE-S-TBP混合溶液（由3mL浓度为0.1mmol/mL的油酸镉ODE溶液与3mL浓度为2mmol/mL的S-TBP混合），滴加速度为3mL/h；滴加完毕后，降温到室温，提纯得到CdZnSe/CdZnSeS/ZnSeS/CdZnS量子点。(4) The third shell coating: Take 5.0 mL of the CdZnSe/CdZnSeS/ZnSeS quantum dot solution from step (3), 10mmol zinc acetate, 25mmol oleic acid and 10g ODE and mix in a three-necked flask. Under nitrogen protection, heat up to 150 React at ℃ for 30min; warm up to 300℃, start to add dropwise Cd-ODE-S-TBP mixed solution (mix 3mL of cadmium oleate ODE solution with a concentration of 0.1mmol/mL and 3mL of S-TBP with a concentration of 2mmol/mL), The dropping rate is 3mL/h; after the dropping, the temperature is lowered to room temperature, and CdZnSe/CdZnSeS/ZnSeS/CdZnS quantum dots are obtained by purification.
通过TEM统计量子点的尺寸平均值（以下实施例相同），实施例1中， CdZnSe量子点核的粒径为5.0nm，CdZnSeS第一壳层的厚度为1.5nm，ZnSeS第二壳层的厚度为0.5nm，CdZnS第三壳层厚度为3.0nm。Statistics of the average size of quantum dots by TEM (the same in the following examples), in Example 1, the particle size of the CdZnSe quantum dot core is 5.0nm, the thickness of the first shell of CdZnSeS is 1.5nm, and the thickness of the second shell of ZnSeS The thickness of the third shell of CdZnS is 0.5nm and 3.0nm.
实施例2Example 2
（1）量子点核制备：取4mmol碱式碳酸锌、4.0mL油酸、15g十八烯加入三口烧瓶，氮气氛围保护下，升温至280℃ 形成澄清透明的溶液；然后向三口烧瓶中依次注入2.0mL浓度为0.5mmol/mL的Se-ODE悬浮液和1.0mL浓度为0.2mmol/mL的油酸镉ODE溶液，升温至300℃，补加1.0mL浓度为 2mmol/mL的Se-TBP溶液，继续升温至310℃反应30min。(1) Preparation of quantum dot core: Take 4mmol basic zinc carbonate, 4.0mL oleic acid, and 15g octadecene into a three-necked flask. Under the protection of nitrogen atmosphere, heat up to 280℃ to form a clear and transparent solution; then inject into the three-necked flask one by one 2.0mL Se-ODE suspension with a concentration of 0.5mmol/mL and 1.0mL cadmium oleate ODE solution with a concentration of 0.2mmol/mL, warm up to 300°C, add 1.0mL of Se-TBP solution with a concentration of 2mmol/mL, Continue to heat up to 310°C and react for 30 minutes.
（2）第一壳层包覆：将步骤（1）的溶液降温到室温，氮气氛围保护下，加入2mmol醋酸锌和5mmol油酸，然后升温到180℃通氮气30min，升温到300℃，开始滴加Cd-ODE-Se-S-TBP混合溶液（由1.5mL浓度为0.1mmol/mL的油酸镉ODE溶液、0.8mL浓度为1mmol/mL的Se-TBP以及0.2mL浓度为1mmol/mL的S-TBP混合），滴加速度为2mL/h，滴加完毕后，降温到室温。(2) First shell coating: Cool the solution of step (1) to room temperature, under the protection of nitrogen atmosphere, add 2mmol zinc acetate and 5mmol oleic acid, then heat up to 180°C and blow nitrogen for 30min, then heat up to 300°C, start Add dropwise the Cd-ODE-Se-S-TBP mixed solution (from 1.5 mL of cadmium oleate ODE solution with a concentration of 0.1 mmol/mL, 0.8 mL of Se-TBP with a concentration of 1 mmol/mL, and 0.2 mL with a concentration of 1 mmol/mL S-TBP mixing), the dripping rate is 2mL/h, after the dripping is completed, the temperature is reduced to room temperature.
（3）第二壳层包覆：氮气氛围保护下，向步骤（2）的溶液加入4mmol醋酸锌和8mmol 油酸，然后升温到180℃通氮气30min，升温到300℃，开始滴加Se-S-TBP混合溶液（由1.5mL 浓度为2mmol/mL的Se-TBP与0.5mL浓度为2mmol/mL的S-TBP混合），滴加速度为2mL/h；滴加完毕后，降温到室温，提纯得到CdZnSe/CdZnSeS/ZnSeS量子点，然后溶于20mL ODE中备用。(3) Second shell coating: Under the protection of nitrogen atmosphere, add 4mmol zinc acetate and 8mmol oleic acid to the solution of step (2), then heat up to 180°C and purge nitrogen for 30min, heat up to 300°C, and start adding Se- S-TBP mixed solution (mixed with 1.5mL Se-TBP with a concentration of 2mmol/mL and 0.5mL S-TBP with a concentration of 2mmol/mL), the dropping rate is 2mL/h; after the addition, the temperature is reduced to room temperature for purification The CdZnSe/CdZnSeS/ZnSeS quantum dots were obtained, and then dissolved in 20 mL ODE for use.
（4）第三壳层包覆：取5.0mL步骤（3）的CdZnSe/CdZnSeS/ZnSeS量子点溶液、10mmol乙酸锌、25mmol油酸和10g ODE于三口烧瓶中混合，氮气保护下，升温到150℃反应30min；升温到300℃，开始滴加Cd-ODE-S-TBP混合溶液（由3mL浓度为0.2mmol/mL的油酸镉ODE溶液与3mL浓度为2mmol/mL的S-TBP混合），滴加速度为3mL/h；滴加完毕后，降温到室温，提纯得到CdZnSe/CdZnSeS/ZnSeS/CdZnS量子点。(4) The third shell coating: Take 5.0 mL of the CdZnSe/CdZnSeS/ZnSeS quantum dot solution from step (3), 10mmol zinc acetate, 25mmol oleic acid and 10g ODE and mix in a three-necked flask. Under nitrogen protection, heat up to 150 React at ℃ for 30 minutes; increase the temperature to 300 ℃, and start to add Cd-ODE-S-TBP mixed solution (mixing 3mL of cadmium oleate ODE solution with a concentration of 0.2mmol/mL and 3mL of S-TBP with a concentration of 2mmol/mL), The dropping rate is 3mL/h; after the dropping, the temperature is lowered to room temperature, and CdZnSe/CdZnSeS/ZnSeS/CdZnS quantum dots are obtained by purification.
实施例2中，CdZnSe量子点核的粒径为3.0nm，CdZnSeS第一壳层的厚度为0.5nm，ZnSeS第二壳层的厚度为3.0nm，CdZnS第三壳层厚度为3.0nm。In Example 2, the particle size of the CdZnSe quantum dot core is 3.0 nm, the thickness of the first shell layer of CdZnSeS is 0.5 nm, the thickness of the second shell layer of ZnSeS is 3.0 nm, and the thickness of the third shell layer of CdZnS is 3.0 nm.
实施例3Example 3
（1）量子点核制备：取6mmol碱式碳酸锌、4.0mL油酸、15g十八烯加入三口烧瓶，氮气氛围保护下，升温至280℃ 形成澄清透明的溶液；然后向三口烧瓶中依次注入2.0mL浓度为0.5mmol/mL的Se-ODE悬浮液和1.2mL浓度为0.2mmol/mL的油酸镉ODE溶液，升温至300℃，补加1.0mL浓度为 2mmol/mL的Se-TBP溶液，继续升温至310℃ 反应30min；然后补加1.5mL浓度为2mmol/ml的Se-TBP溶液，接着反应30min。(1) Preparation of quantum dot core: Take 6mmol basic zinc carbonate, 4.0mL oleic acid, and 15g octadecene into a three-necked flask, and under the protection of nitrogen atmosphere, heat up to 280℃ to form a clear and transparent solution; then pour into the three-necked flask one by one 2.0mL Se-ODE suspension with a concentration of 0.5mmol/mL and 1.2mL cadmium oleate ODE solution with a concentration of 0.2mmol/mL, warm up to 300°C, add 1.0mL of Se-TBP solution with a concentration of 2mmol/mL, Continue to increase the temperature to 310°C and react for 30 minutes; then add 1.5 mL of Se-TBP solution with a concentration of 2 mmol/ml, and then react for 30 minutes.
（2）第一壳层包覆：将步骤（1）的溶液降温到室温，氮气氛围保护下，加入2mmol醋酸锌和5mmol油酸，然后升温到180℃通氮气30min，升温到300℃，开始滴加Cd-ODE-Se-S-TBP混合溶液（由2mL浓度为0.1mmol/mL的油酸镉ODE溶液、0.7mL浓度为2mmol/mL的Se-TBP以及0.3mL浓度为2mmol/mL的S-TBP混合），滴加速度为3mL/h，滴加完毕后，降温到室温。(2) First shell coating: Cool the solution of step (1) to room temperature, under the protection of nitrogen atmosphere, add 2mmol zinc acetate and 5mmol oleic acid, then heat up to 180°C and blow nitrogen for 30min, then heat up to 300°C, start Add dropwise Cd-ODE-Se-S-TBP mixed solution (from 2mL of cadmium oleate ODE solution with a concentration of 0.1mmol/mL, 0.7mL of Se-TBP with a concentration of 2mmol/mL and 0.3mL of S with a concentration of 2mmol/mL -TBP mixing), the dripping rate is 3mL/h, after the dripping is completed, the temperature is reduced to room temperature.
（3）第二壳层包覆：氮气氛围保护下，向步骤（2）的溶液加入4mmol醋酸锌和8mmol 油酸，然后升温到180℃通氮气30min，升温到300℃，开始滴加Se-S-TBP混合溶液（由1.0mL 浓度为2mmol/mL的Se-TBP与1.0mL浓度为2mmol/mL的S-TBP混合），滴加速度为2mL/h；滴加完毕后，降温到室温，提纯得到CdZnSe/CdZnSeS/ZnSeS量子点，然后溶于20mL ODE中备用。(3) Second shell coating: Under the protection of nitrogen atmosphere, add 4mmol zinc acetate and 8mmol oleic acid to the solution of step (2), then heat up to 180°C and purge nitrogen for 30min, heat up to 300°C, and start adding Se- S-TBP mixed solution (mixing 1.0mL of Se-TBP with a concentration of 2mmol/mL and 1.0mL of S-TBP with a concentration of 2mmol/mL), the dropping rate is 2mL/h; after the addition, the temperature is reduced to room temperature for purification The CdZnSe/CdZnSeS/ZnSeS quantum dots were obtained, and then dissolved in 20 mL ODE for use.
（4）第三壳层包覆：取5.0mL步骤（3）的CdZnSe/CdZnSeS/ZnSeS量子点溶液、10mmol乙酸锌、25mmol油酸和10g ODE于三口烧瓶中混合，氮气保护下，升温到150℃反应30min；升温到300℃，开始滴加Cd-ODE-S-TBP混合溶液（由2.5mL浓度为0.2mmol/mL的油酸镉ODE溶液与1.5mL浓度为2mmol/mL的S-TBP混合），滴加速度为4mL/h；滴加完毕后，降温到室温，提纯得到CdZnSe/CdZnSeS/ZnSeS/CdZnS量子点。(4) The third shell coating: Take 5.0 mL of the CdZnSe/CdZnSeS/ZnSeS quantum dot solution from step (3), 10mmol zinc acetate, 25mmol oleic acid and 10g ODE and mix in a three-necked flask. Under nitrogen protection, heat up to 150 Reaction at ℃ for 30min; heating to 300℃, start to add dropwise Cd-ODE-S-TBP mixed solution (mix 2.5mL of cadmium oleate ODE solution with a concentration of 0.2mmol/mL and 1.5mL of S-TBP with a concentration of 2mmol/mL ), the dropping rate is 4mL/h; after the dropping is completed, the temperature is lowered to room temperature, and the CdZnSe/CdZnSeS/ZnSeS/CdZnS quantum dots are obtained by purification.
实施例3中，CdZnSe量子点核的粒径为8.0nm，CdZnSeS第一壳层的厚度为1.0nm，ZnSeS第二壳层的厚度为2.0nm，CdZnS第三壳层厚度为0.5nm。In Example 3, the particle size of the CdZnSe quantum dot core is 8.0 nm, the thickness of the first shell layer of CdZnSeS is 1.0 nm, the thickness of the second shell layer of ZnSeS is 2.0 nm, and the thickness of the third shell layer of CdZnS is 0.5 nm.
实施例4Example 4
（1）量子点核制备：取4mmol碱式碳酸锌、4.0mL油酸、15g十八烯加入三口烧瓶，氮气氛围保护下，升温至280℃ 形成澄清透明的溶液；然后向三口烧瓶中依次注入2.0mL浓度为0.5mmol/mL的Se-ODE悬浮液和1.2mL浓度为0.2mmol/mL的油酸镉ODE溶液，升温至300℃，补加1.0mL浓度为 2mmol/mL的Se-TBP溶液，继续升温至310℃反应90min。(1) Preparation of quantum dot core: Take 4mmol basic zinc carbonate, 4.0mL oleic acid, and 15g octadecene into a three-necked flask. Under the protection of nitrogen atmosphere, heat up to 280℃ to form a clear and transparent solution; then inject into the three-necked flask one by one 2.0mL Se-ODE suspension with a concentration of 0.5mmol/mL and 1.2mL cadmium oleate ODE solution with a concentration of 0.2mmol/mL, warm up to 300°C, add 1.0mL of Se-TBP solution with a concentration of 2mmol/mL, Continue to heat up to 310°C and react for 90 minutes.
（2）第一壳层包覆：将步骤（1）的溶液降温到室温，氮气氛围保护下，加入6mmol醋酸锌和12mmol油酸，然后升温到180℃通氮气30min，升温到300℃，开始滴加Cd-ODE-Se-S-TBP混合溶液（由2.5mL浓度为0.1mmol/mL的油酸镉ODE溶液、1.5mL浓度为2mmol/mL的Se-TBP以及1mL浓度为2mmol/mL的S-TBP混合），滴加速度为5mL/h，滴加完毕后，降温到室温。(2) The first shell layer coating: cool the solution of step (1) to room temperature, add 6mmol zinc acetate and 12mmol oleic acid under the protection of nitrogen atmosphere, then heat up to 180°C and blow nitrogen for 30min, then heat up to 300°C, start Add dropwise Cd-ODE-Se-S-TBP mixed solution (from 2.5 mL of cadmium oleate ODE solution with a concentration of 0.1 mmol/mL, 1.5 mL of Se-TBP with a concentration of 2 mmol/mL, and 1 mL of S with a concentration of 2 mmol/mL -TBP mixing), the dripping rate is 5mL/h, after the dripping is completed, the temperature is reduced to room temperature.
（3）第二壳层包覆：氮气氛围保护下，向步骤（2）的溶液加入3mmol醋酸锌和6mmol 油酸，然后升温到180℃ 通氮气30min，升温到300℃，开始滴加Se-S-TBP混合溶液（由0.2mL 浓度为1.5mmol/mL的Se-TBP与1.8mL浓度为1.5mmol/mL的S-TBP混合），滴加速度为1mL/h；滴加完毕后，降温到室温，提纯得到CdZnSe/CdZnSeS/ZnSeS量子点，然后溶于20mL ODE中备用。(3) Second shell coating: Under the protection of nitrogen atmosphere, add 3mmol zinc acetate and 6mmol oleic acid to the solution of step (2), then heat up to 180°C and vent nitrogen for 30min, heat up to 300°C, and start adding Se- dropwise. S-TBP mixed solution (mixed with 0.2mL Se-TBP with a concentration of 1.5mmol/mL and 1.8mL S-TBP with a concentration of 1.5mmol/mL), the dropping rate is 1mL/h; after the addition, the temperature is cooled to room temperature , Purified to obtain CdZnSe/CdZnSeS/ZnSeS quantum dots, and then dissolved in 20mL ODE for later use.
（4）第三壳层包覆：取5.0mL步骤（3）的CdZnSe/CdZnSeS/ZnSeS量子点溶液、10mmol乙酸锌、25mmol油酸和10g ODE于三口烧瓶中混合，氮气保护下，升温到150℃反应30min；升温到300℃，开始滴加Cd-ODE-S-TBP混合溶液（由4mL浓度为0.1mmol/mL的油酸镉ODE溶液与2mL浓度为2mmol/mL的S-TBP混合），滴加速度为3mL/h；滴加完毕后，降温到室温，提纯得到CdZnSe/CdZnSeS/ZnSeS/CdZnS量子点。(4) The third shell coating: Take 5.0 mL of the CdZnSe/CdZnSeS/ZnSeS quantum dot solution from step (3), 10mmol zinc acetate, 25mmol oleic acid and 10g ODE and mix in a three-necked flask. Under nitrogen protection, heat up to 150 React at ℃ for 30 minutes; increase the temperature to 300℃, and start to add Cd-ODE-S-TBP mixed solution (mixing 4mL of cadmium oleate ODE solution with a concentration of 0.1mmol/mL and 2mL of S-TBP with a concentration of 2mmol/mL), The dropping rate is 3mL/h; after the dropping, the temperature is lowered to room temperature, and CdZnSe/CdZnSeS/ZnSeS/CdZnS quantum dots are obtained by purification.
实施例4中，CdZnSe量子点核的粒径为5.5nm，CdZnSeS第一壳层的厚度为3.0nm，ZnSeS第二壳层的厚度为1.0nm，CdZnS第三壳层厚度为2.0nm。In Example 4, the particle size of the CdZnSe quantum dot core is 5.5 nm, the thickness of the first shell layer of CdZnSeS is 3.0 nm, the thickness of the second shell layer of ZnSeS is 1.0 nm, and the thickness of the third shell layer of CdZnS is 2.0 nm.
实施例5Example 5
（1）量子点核制备：取6mmol碱式碳酸锌、4.0mL油酸、15g十八烯加入三口烧瓶，氮气氛围保护下，升温至280℃ 形成澄清透明的溶液；然后向三口烧瓶中依次注入2.0mL浓度为0.5mmol/mL的Se-ODE悬浮液和1.2mL浓度为0.2mmol/mL的油酸镉ODE前驱体，升温至300℃，补加1.5mL浓度为 2mmol/mL的Se-TBP溶液，继续升温至310℃反应60min。(1) Preparation of quantum dot core: Take 6mmol basic zinc carbonate, 4.0mL oleic acid, and 15g octadecene into a three-necked flask, and under the protection of nitrogen atmosphere, heat up to 280℃ to form a clear and transparent solution; then pour into the three-necked flask one by one 2.0mL Se-ODE suspension with a concentration of 0.5mmol/mL and 1.2mL cadmium oleate ODE precursor with a concentration of 0.2mmol/mL, heated to 300℃, and supplemented with 1.5mL of Se-TBP solution with a concentration of 2mmol/mL , Continue to heat up to 310 ℃ for 60 minutes.
（2）第一壳层包覆：将步骤（1）的溶液降温到室温，氮气氛围保护下，加入2mmol醋酸锌和5mmol油酸，然后升温到180℃通氮气30min，升温到300℃，然后注入Cd-ODE-Se-S-TBP混合溶液（由1.0mL浓度为0.1mmol/mL的油酸镉ODE溶液、0.7mL浓度为2mmol/mL的Se-TBP以及0.3mL浓度为2mmol/mL的S-TBP混合），300℃ 反应30min，反应完毕，降温到室温。(2) Coating of the first shell layer: cool the solution of step (1) to room temperature, add 2mmol zinc acetate and 5mmol oleic acid under the protection of nitrogen atmosphere, then heat up to 180°C and blow nitrogen for 30min, then heat up to 300°C, then Inject the Cd-ODE-Se-S-TBP mixed solution (from 1.0 mL of cadmium oleate ODE solution with a concentration of 0.1 mmol/mL, 0.7 mL of Se-TBP with a concentration of 2 mmol/mL, and 0.3 mL of S with a concentration of 2 mmol/mL -TBP mixed), react at 300°C for 30min, after the reaction is complete, cool to room temperature.
（3）第二壳层包覆：氮气氛围保护下，向步骤（2）的溶液加入4mmol醋酸锌和8mmol 油酸，然后升温到180℃ 通氮气30min，升温到300℃，注入Se-S-TBP混合溶液（由1.0mL 浓度为2mmol/mL的Se-TBP与1.0mL浓度为2mmol/mL的S-TBP混合）；300℃反应30min，降温到室温，提纯得到CdZnSe/CdZnSeS/ZnSeS量子点，然后溶于20mL ODE中备用。(3) Second shell coating: Under the protection of nitrogen atmosphere, add 4mmol zinc acetate and 8mmol oleic acid to the solution of step (2), then heat up to 180°C with nitrogen for 30min, heat up to 300°C, and inject Se-S- TBP mixed solution (mixing 1.0mL Se-TBP with a concentration of 2mmol/mL and 1.0mL S-TBP with a concentration of 2mmol/mL); react at 300°C for 30 minutes, cool to room temperature, and purify to obtain CdZnSe/CdZnSeS/ZnSeS quantum dots. Then dissolve in 20mL Spare in ODE.
（4）第三壳层包覆：取5.0mL步骤（3）的CdZnSe/CdZnSeS/ZnSeS量子点溶液、10mmol乙酸锌、25mmol油酸和10g ODE于三口烧瓶中混合，氮气保护下，升温到150℃反应30min；然后升温到300℃，注入2mL 2mmol/mL的S-TBP溶液；反应5min后注入2mL 0.1mol/mL的油酸镉溶液，300℃ 反应30min，降温到室温，提纯得到CdZnSe/CdZnSeS/ZnSeS/CdZnS量子点。(4) The third shell coating: Take 5.0 mL of the CdZnSe/CdZnSeS/ZnSeS quantum dot solution from step (3), 10mmol zinc acetate, 25mmol oleic acid and 10g ODE and mix in a three-necked flask. Under nitrogen protection, heat up to 150 React at ℃ for 30min; then heat to 300℃, inject 2mL of 2mmol/mL S-TBP solution; after react for 5min, inject 2mL of 0.1mol/mL cadmium oleate solution, react at 300℃ for 30min, cool to room temperature, and purify to obtain CdZnSe/CdZnSeS /ZnSeS/CdZnS quantum dots.
实施例5中，CdZnSe量子点核的粒径为7.0nm，CdZnSeS第一壳层的厚度为1.0nm，ZnSeS第二壳层的厚度为2.0nm，CdZnS第三壳层厚度为1.0nm。In Example 5, the particle size of the CdZnSe quantum dot core is 7.0 nm, the thickness of the CdZnSeS first shell layer is 1.0 nm, the thickness of the ZnSeS second shell layer is 2.0 nm, and the thickness of the CdZnS third shell layer is 1.0 nm.
对比例1Comparative example 1
（1）量子点核制备：取4mmol碱式碳酸锌、4.0mL油酸、15g十八烯加入三口烧瓶，氮气氛围保护下，升温至280℃ 形成澄清透明的溶液；然后向三口烧瓶中依次注入2.0mL浓度为0.5mmol/mL的Se-ODE悬浮液和2.0mL浓度为0.2mmol/mL的油酸镉ODE溶液，升温至300℃，补加1.0mL浓度为 2mmol/mL的Se-TBP溶液，继续升温至310℃ 反应90min。(1) Preparation of quantum dot core: Take 4mmol basic zinc carbonate, 4.0mL oleic acid, and 15g octadecene into a three-necked flask. Under the protection of nitrogen atmosphere, heat up to 280℃ to form a clear and transparent solution; then inject into the three-necked flask one by one 2.0mL Se-ODE suspension with a concentration of 0.5mmol/mL and 2.0mL cadmium oleate ODE solution with a concentration of 0.2mmol/mL, warm up to 300°C, add 1.0mL of Se-TBP solution with a concentration of 2mmol/mL, Continue to heat up to 310°C and react for 90 minutes.
（2）第一壳层包覆：将步骤（1）的溶液降温到室温，氮气氛围保护下，加入4mmol醋酸锌和8mmol油酸，然后升温到180℃通氮气30min，升温到300℃，开始滴加Se-S-TBP混合溶液（1mL浓度为2mmol/mL的Se-TBP以及0.5mL浓度为2mmol/mL的S-TBP混合），滴加速度为3mL/h，滴加完毕后，降温到室温，提纯得到CdZnSe/ZnSeS量子点，然后溶于20mL ODE中备用。(2) First shell coating: Cool the solution of step (1) to room temperature, add 4mmol zinc acetate and 8mmol oleic acid under the protection of nitrogen atmosphere, then heat up to 180°C and blow nitrogen for 30min, then heat up to 300°C, start Drop the Se-S-TBP mixed solution (1mL of Se-TBP with a concentration of 2mmol/mL and 0.5mL of S-TBP with a concentration of 2mmol/mL) at a rate of 3mL/h. After the addition is complete, cool to room temperature , Purified to obtain CdZnSe/ZnSeS quantum dots, and then dissolved in 20mL ODE for later use.
（3）第二壳层包覆：取5.0mL步骤（2）的CdZnSe/ZnSeS量子点溶液、10mmol乙酸锌、25mmol油酸和10g ODE于三口烧瓶中混合，氮气保护下，升温到150℃反应30min；升温到300℃，开始滴加3mL浓度为2mmol/mL的S-TBP溶液，滴加速度为3mL/h；反应完毕后，降温到室温，提纯得到CdZnSe/ZnSeS/ZnS量子点。(3) Second shell coating: Take 5.0 mL of the CdZnSe/ZnSeS quantum dot solution of step (2), 10 mmol zinc acetate, 25 mmol oleic acid and 10 g ODE and mix in a three-necked flask. Under nitrogen protection, heat up to 150°C for reaction 30min; The temperature is raised to 300℃, and 3mL of S-TBP solution with a concentration of 2mmol/mL is added dropwise at a rate of 3mL/h; after the reaction is completed, the temperature is lowered to room temperature, and CdZnSe/ZnSeS/ZnS quantum dots are purified.
对比例1中，CdZnSe量子点核的粒径为5.5nm，ZnSeS第一壳层的厚度为2.0nm，ZnSeS第二壳层的厚度为3.0nm。In Comparative Example 1, the particle size of the CdZnSe quantum dot core is 5.5 nm, the thickness of the first shell layer of ZnSeS is 2.0 nm, and the thickness of the second shell layer of ZnSeS is 3.0 nm.
测试实施例1至实施例5、对比例1制得的核壳量子点的荧光发射峰值（PL）、荧光半峰宽（FWHM）以及光致荧光量子效率（Qys）。测试结果记录于表1。测试时，以450nm的蓝色LED作为背光光源激发核壳量子点（已提纯）的甲苯溶液发光，利用仪器测试核壳量子点的发射光谱，从而可得到荧光发射峰值以及荧光半峰宽。光致荧光量子效率的测试方法为：利用450nm蓝色LED作为背光光源，利用积分球分别测试蓝色背光光谱和透过量子点溶液的光谱，利用谱图的积分面积计算量子效率，量子效率=量子点发射峰面积/（蓝色背光峰面积-透过量子点的甲苯溶液未被吸收的蓝色峰面积）*100%。The core-shell quantum dots prepared in Examples 1 to 5 and Comparative Example 1 were tested for their fluorescence emission peak (PL), fluorescence half-width (FWHM) and photoluminescence quantum efficiency (Qys). The test results are recorded in Table 1. During the test, a 450nm blue LED was used as the backlight source to excite the toluene solution of the core-shell quantum dots (purified) to emit light, and the emission spectrum of the core-shell quantum dots was tested with an instrument to obtain the fluorescence emission peak and the fluorescence half-width. The test method of photoluminescence quantum efficiency is: use 450nm blue LED as the backlight light source, use the integrating sphere to test the blue backlight spectrum and the spectrum through the quantum dot solution respectively, use the integral area of the spectrum to calculate the quantum efficiency, quantum efficiency = Quantum dot emission peak area/(blue backlight peak area-the blue peak area that is not absorbed by the toluene solution passing through the quantum dot) * 100%.
实施例1至实施例5、对比例1制得的核壳量子点分别用于制备QLED器件，然后测试各QLED器件的发射峰值（EL）、外量子效率（EQE）以及器件的初始亮度为1000cd/m 2条件下亮度衰减50%时的时间（T 50）。测试结果记录于表1。 The core-shell quantum dots prepared in Examples 1 to 5 and Comparative Example 1 were used to prepare QLED devices, and then the emission peak (EL) and external quantum efficiency (EQE) of each QLED device were tested and the initial brightness of the device was 1000 cd. /m 2 The time when the brightness attenuates by 50% (T 50 ). The test results are recorded in Table 1.
外量子效率的测试方法为：采用Keithley2400测定量子点发光器件的电流密度-电压曲线，采用积分球（FOIS-1）结合海洋光学的光谱仪（QE-pro）测定量子点发光器件的亮度。根据测定得到的电流密度与亮度计算量子点发光器件的外量子效率。外量子效率表征在观测方向上发光器件发出的光子数与注入器件的电子数之间的比值，是表征器发光器件发光效率的重要参数，外量子效率越高，说明器件的发光效率越高。The test method of external quantum efficiency is as follows: Keithley 2400 is used to measure the current density-voltage curve of quantum dot light-emitting devices, and the integrating sphere (FOIS-1) combined with Ocean Optics spectrometer (QE-pro) is used to measure the brightness of quantum dot light-emitting devices. According to the measured current density and brightness, the external quantum efficiency of the quantum dot light-emitting device is calculated. The external quantum efficiency characterizes the ratio between the number of photons emitted by the light-emitting device and the number of electrons injected into the device in the observation direction, and is an important parameter characterizing the luminous efficiency of the light-emitting device. The higher the external quantum efficiency, the higher the luminous efficiency of the device.
QLED器件的制备方法可参考以下步骤，变量仅为发光层的材料，其它条件相同。The preparation method of the QLED device can refer to the following steps, the variable is only the material of the light-emitting layer, and other conditions are the same.
（1）对厚度为180nm的阳极ITO（氧化铟锡）进行清洗处理：用乙醇、去离子水和丙酮分别超声清洗处理10min，然后用N 2吹干附着于ITO表面的液体，并经过氧气等离子体处理10min，以清除ITO表面的杂质，得到清洁的ITO透明导电玻璃。 (1) Clean the anode ITO (indium tin oxide) with a thickness of 180nm: ultrasonically clean with ethanol, deionized water and acetone for 10 minutes, then dry the liquid attached to the ITO surface with N 2 and pass it through oxygen plasma Body treatment for 10 minutes to remove impurities on the ITO surface to obtain clean ITO transparent conductive glass.
（2）制作空穴注入层以及空穴传输层：在空气环境中，在清洁的ITO透明导电玻璃上以4000转/分钟的转速旋涂PEDOT:PSS（聚对苯乙烯磺酸溶液），时间为50秒，旋涂完成后在空气中150℃下退火处理30分钟，再将其转移至氮气环境的手套箱中，130℃退火20分钟，最终在ITO表面形成一层PEDOT:PSS层，即空穴注入层；然后在PEDOT:PSS层上以2000转/分钟的转速旋涂聚((9,9-二辛基芴-2,7-二基)-共（4,4'-(N-(4-仲-丁基苯基)二苯胺))（TFB）的氯苯溶液（浓度为8mg/mL），旋涂时间为45秒，旋涂完成后在手套箱中150℃退火30分钟形成PVK空穴传输层。(2) Fabrication of hole injection layer and hole transport layer: In an air environment, spin-coating PEDOT:PSS (poly-p-styrene sulfonic acid solution) on clean ITO transparent conductive glass at a speed of 4000 revolutions per minute. For 50 seconds, after the spin coating is completed, annealed at 150°C in air for 30 minutes, then transferred to a glove box in a nitrogen environment, annealed at 130°C for 20 minutes, and finally a layer of PEDOT:PSS is formed on the ITO surface, namely Hole injection layer; then spin-coated poly((9,9-dioctylfluorene-2,7-diyl)-co(4,4'-(N -(4-sec-butylphenyl)diphenylamine)) (TFB) in chlorobenzene solution (concentration of 8mg/mL), spin coating time is 45 seconds, after spin coating is completed, annealed at 150°C for 30 minutes in a glove box The PVK hole transport layer is formed.
（3）制作发光层：在空穴传输层上旋涂量子点墨水（量子点分别为实施例1至实施例4、对比例1制得核壳量子点，溶剂为正辛烷，浓度为20mg/mL），转速为2000转/分钟，旋涂时间为45s。(3) Fabrication of the luminescent layer: spin-coated quantum dot ink on the hole transport layer (quantum dots are in Example 1 to Example 4 and Comparative Example 1 respectively to prepare core-shell quantum dots, the solvent is n-octane, and the concentration is 20 mg /mL), the rotation speed is 2000 rpm, and the spin coating time is 45s.
（4）制作氧化锌纳米晶薄膜：在发光层上以2500转/分钟的转速旋涂氧化锌纳米晶溶液（溶剂为乙醇，浓度为30mg/mL），旋涂时间为50s，旋涂完成后在手套箱中120℃下退火处理30min，最终在发光层表面形成一层氧化锌纳米晶薄膜。(4) Making zinc oxide nanocrystalline film: spin-coating zinc oxide nanocrystalline solution (solvent is ethanol, concentration is 30mg/mL) on the light-emitting layer at a speed of 2500 rpm, the spin coating time is 50 seconds, after the spin coating is completed Annealing in a glove box at 120°C for 30 minutes, finally a zinc oxide nanocrystalline film is formed on the surface of the light-emitting layer.
（5）制作电极：步骤（4）制得的器件置于真空蒸镀仓内，蒸镀阴极银电极，厚度为100nm。(5) Fabrication of electrodes: the device obtained in step (4) is placed in a vacuum evaporation chamber, and the cathode silver electrode is evaporated with a thickness of 100 nm.
表1Table 1
 To PL(nm)PL(nm) QysQys FWHM(nm)FWHM(nm) EL(nm)EL(nm) EQEEQE T 50(h) T 50 (h)
实施例1Example 1 472472 96.3%96.3% 1212 475475 12.3%12.3% 1600016000
实施例2Example 2 474474 93.2%93.2% 1313 476476 13.8%13.8% 1720017,200
实施例3Example 3 476476 96.8%96.8% 1515 478478 14.6%14.6% 1800018000
实施例4Example 4 479479 99.2%99.2% 1818 480480 15.2%15.2% 2000020000
实施例5Example 5 477477 94.2%94.2% 1919 480480 11.2%11.2% 96009600
对比例1Comparative example 1 475475 92.2%92.2% 24twenty four 478478 9.8%9.8% 52005200
 对比例1的核壳量子点结构为CdZnSe/ZnSeS/ZnS，实施例1-5的核壳量子点的结构为CdZnSe/CdZnSeS/ZnSeS/CdZnS。从表1的实验数据可以看出，实施例1-5的核壳量子点的光致荧光量子效率Qys均高于对比例1的核壳量子点，此外，实施例1-5的核壳量子点的荧光半峰宽（FWHM）比对比例的核壳量子点更窄，说明本申请提供的核壳量子点的结构有利于提高核壳量子点的光致荧光量子效率，减小核壳量子点的荧光半峰宽，利用实施例1-5的核壳量子点制备的QLED的外量子点效率更高，使用寿命更长。The core-shell quantum dot structure of Comparative Example 1 is CdZnSe/ZnSeS/ZnS, and the structure of the core-shell quantum dots of Examples 1-5 is CdZnSe/CdZnSeS/ZnSeS/CdZnS. From the experimental data in Table 1, it can be seen that the photoluminescence quantum efficiency Qys of the core-shell quantum dots of Examples 1-5 is higher than that of the core-shell quantum dots of Comparative Example 1. In addition, the core-shell quantum dots of Examples 1-5 The fluorescence half-width (FWHM) of the dots is narrower than that of the core-shell quantum dots of the comparative example, indicating that the structure of the core-shell quantum dots provided in this application is beneficial to improve the photoluminescence quantum efficiency of the core-shell quantum dots and reduce the core-shell quantum dots The fluorescence half-peak width of the dots, the QLED prepared by using the core-shell quantum dots of Examples 1-5 has higher external quantum dot efficiency and longer service life.
此外，实施例1-4的核壳量子点的各壳层为均质壳层（壳层生长时采用滴加的方式添加反应前体），实施例5的核壳量子点的各壳层为非均质壳层（壳层生长时采用一次性注入的方式添加反应前体），从表1的实验数据可以看出，采用实施例1-4的核壳量子点制备的QLED的外量子效率更高，器件的使用寿命更长。In addition, the shell layers of the core-shell quantum dots of Examples 1-4 are homogeneous shell layers (the reaction precursor is added dropwise when the shell layer is grown), and the shell layers of the core-shell quantum dots of Example 5 are Heterogeneous shell layer (the reaction precursor is added by one-time injection during shell growth). From the experimental data in Table 1, it can be seen that the external quantum efficiency of the QLED prepared with the core-shell quantum dots of Examples 1-4 Higher, the lifetime of the device is longer.
以上描述了本申请的基本原理、主要特征和本申请的优点。本行业的技术人员应该了解，本申请不受上述实施例的限制，上述实施例和说明书中描述的只是本申请的原理，在不脱离本申请精神和范围的前提下本申请还会有各种变化和改进，这些变化和改进都落入要求保护的本申请的范围内。本申请要求的保护范围由所附的权利要求书及其等同物界定。The basic principles, main features and advantages of the application are described above. Those skilled in the industry should understand that this application is not limited by the above-mentioned embodiments. The above-mentioned embodiments and the specification describe only the principles of this application, and there will be various details in this application without departing from the spirit and scope of this application. Changes and improvements, these changes and improvements fall within the scope of the claimed application. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims (12)

  1. 核壳量子点，其特征在于，包括量子点核以及由内到外依次包覆在所述量子点核上的第一壳层、第二壳层和第三壳层，所述量子点核为CdZnSe，所述第一壳层为CdZnSeS，所述第二壳层为ZnSeS，所述第三壳层为CdZnS。The core-shell quantum dot is characterized by comprising a quantum dot core and a first shell layer, a second shell layer, and a third shell layer that are sequentially coated on the quantum dot core from the inside to the outside, and the quantum dot core is CdZnSe, the first shell layer is CdZnSeS, the second shell layer is ZnSeS, and the third shell layer is CdZnS.
  2. 根据权利要求1所述的核壳量子点，其特征在于，所述第一壳层、所述第二壳层和所述第三壳层均为均质的壳层。The core-shell quantum dot according to claim 1, wherein the first shell layer, the second shell layer and the third shell layer are all homogeneous shell layers.
  3. 根据权利要求1所述的核壳量子点，其特征在于，所述量子点核的粒径为3nm~8nm，所述第一壳层的厚度为0.5nm~3nm，所述第二壳层的厚度为0.5nm~3nm，所述第三壳层的厚度为0.5nm~3nm。The core-shell quantum dot according to claim 1, wherein the particle size of the quantum dot core is 3nm~8nm, the thickness of the first shell layer is 0.5nm~3nm, and the thickness of the second shell layer is 0.5nm~3nm. The thickness of the third shell layer is 0.5 nm to 3 nm, and the thickness of the third shell layer is 0.5 nm to 3 nm.
  4. 根据权利要求1所述的核壳量子点，其特征在于，所述核壳量子点的荧光发射峰为470nm~480nm，所述核壳量子点的荧光半峰宽为12nm~18nm。The core-shell quantum dot according to claim 1, wherein the fluorescence emission peak of the core-shell quantum dot is 470 nm to 480 nm, and the fluorescence half-peak width of the core-shell quantum dot is 12 nm to 18 nm.
  5. 根据权利要求1所述的核壳量子点，其特征在于，所述核壳量子点的光致荧光量子效率大于等于90%。The core-shell quantum dot according to claim 1, wherein the photoluminescence quantum efficiency of the core-shell quantum dot is greater than or equal to 90%.
  6. 根据权利要求1-5任一所述的核壳量子点，其特征在于，所述量子点核的HOMO高于所述第一壳层的HOMO，二者的能级差大于等于0.3eV；所述第一壳层的LUMO与所述量子点核的LUMO能级差小于等于0.2eV；所述第一壳层的HOMO高于所述第二壳层的HOMO，二者的能级差大于等于0.2eV；所述第二壳层的LUMO与所述第一壳层的LUMO的能级差小于等于0.1eV；所述第三壳层的HOMO与所述第二壳层的HOMO的能级差小于等于0.1 eV；所述第三壳层的LUMO比所述第二壳层的LUMO低，二者的能级差大于等于0.2eV。The core-shell quantum dot according to any one of claims 1-5, wherein the HOMO of the quantum dot core is higher than the HOMO of the first shell, and the energy level difference between the two is greater than or equal to 0.3 eV; The energy level difference between the LUMO of the first shell layer and the LUMO of the quantum dot core is less than or equal to 0.2 eV; the HOMO of the first shell layer is higher than the HOMO of the second shell layer, and the energy level difference between the two is greater than or equal to 0.2 eV; The energy level difference between the LUMO of the second shell layer and the LUMO of the first shell layer is less than or equal to 0.1 eV; the energy level difference between the HOMO of the third shell layer and the HOMO of the second shell layer is less than or equal to 0.1 eV; The LUMO of the third shell layer is lower than the LUMO of the second shell layer, and the energy level difference between the two is greater than or equal to 0.2 eV.
  7. 根据权利要求1所述的核壳量子点，其特征在于，所述核壳量子点的荧光发射峰为440nm~480nm。The core-shell quantum dot according to claim 1, wherein the fluorescence emission peak of the core-shell quantum dot is 440 nm to 480 nm.
  8. 量子点发光二极管，包括量子点发光层，其特征在于，所述量子点发光层包括权利要求1-7任一所述的核壳量子点。The quantum dot light-emitting diode comprises a quantum dot light-emitting layer, wherein the quantum dot light-emitting layer comprises the core-shell quantum dot according to any one of claims 1-7.
  9. 根据权利要求8所述的量子点发光二极管，其特征在于，所述量子点发光二极管的外量子效率为12%~15%。8. The quantum dot light emitting diode according to claim 8, wherein the external quantum efficiency of the quantum dot light emitting diode is 12%-15%.
  10. 根据权利要求8所述的量子点发光二极管，其特征在于，当所述量子点发光二极管的初始亮度为1000cd/m 2时，所述量子点发光二极管的T 50大于等于9600h。 8. The quantum dot light emitting diode according to claim 8, wherein when the initial brightness of the quantum dot light emitting diode is 1000 cd/m 2 , the T 50 of the quantum dot light emitting diode is greater than or equal to 9600 h.
  11. 量子点组合物，其特征在于，包括如权利要求1-7任一所述的核壳量子点。The quantum dot composition is characterized by comprising the core-shell quantum dot according to any one of claims 1-7.
  12. 显示器件，其特征在于，包括如权利要求1-7任一所述的核壳量子点，或者包括如权利要求8-10任一所述的量子点发光二极管。The display device is characterized in that it comprises the core-shell quantum dot according to any one of claims 1-7, or comprises the quantum dot light-emitting diode according to any one of claims 8-10.
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