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CN-121991683-A - Aqueous phase CdSe@ZnS quantum dot suitable for light-emitting diode without carrier injection, preparation method thereof and light-emitting diode without carrier injection

CN121991683ACN 121991683 ACN121991683 ACN 121991683ACN-121991683-A

Abstract

The embodiment of the specification discloses an aqueous phase CdSe@ZnS quantum dot suitable for a light-emitting diode without carrier injection, a preparation method thereof and the light-emitting diode without carrier injection. According to the method, a water-soluble glutathione ligand is introduced as a surface modifier, a binary system with two phases of water and oil is constructed based on the oil-soluble CdSe@ZnS quantum dots, and the oil-soluble CdSe@ZnS quantum dots can be converted into water-soluble ones due to good coordination of amino groups and mercapto groups of the glutathione ligand, so that the performance of the carrier-free injection type light-emitting diode device is expected to be further improved due to the affinity between the water-phase quantum dot luminescent layer and the insulating layer.

Inventors

  • XIAO YIN
  • YAN XINYAO

Assignees

  • 天津大学

Dates

Publication Date
20260508
Application Date
20241106

Claims (10)

  1. 1. The preparation method of the aqueous phase CdSe@ZnS quantum dot suitable for the light-emitting diode without carrier injection is characterized by comprising the following steps of: Step 1, adding cadmium acetate and zinc oxide into oleic acid for reaction, heating a reaction system to a first temperature, carrying out degassing reaction at the first temperature, and then adding octadecene to heat to a second temperature to obtain a cadmium-zinc precursor liquid; Step 2, adding sulfur powder and selenium powder into tri-n-octyl phosphine for reaction, and heating the reaction system to a third temperature to obtain selenium-sulfur precursor liquid; step 3, injecting the selenium-sulfur precursor liquid obtained in the step 2 into the cadmium-zinc precursor liquid obtained in the step 1, and cooling the reaction system to room temperature after maintaining the reaction system at a second temperature for a period of time to obtain CdSe@ZnS quantum dots; Step 4, washing the CdSe@ZnS quantum dots obtained in the step 3 by using a mixed solution of normal hexane and acetone, and dispersing the washed CdSe@ZnS quantum dots in a nonpolar solvent chloroform to obtain a nonpolar CdSe@ZnS quantum dot solution; step5, dissolving a short-chain amino acid ligand in water to obtain an amino acid ligand solution, and sequentially adding a sodium hydroxide solution, a zinc chloride solution and a thiourea solution into the amino acid ligand solution to obtain a water phase solution; Step 6, adding the aqueous phase solution obtained in the step 5 into the nonpolar CdSe@ZnS quantum dot solution obtained in the step 4, and stirring to obtain a crude product of the aqueous phase CdSe@ZnS quantum dot; And 7, washing the aqueous phase CdSe@ZnS quantum dot crude product obtained in the step 6 with ethanol, and then re-dispersing in deionized water to obtain the aqueous phase CdSe@ZnS quantum dot suitable for the light-emitting diode without carrier injection.
  2. 2. The method for preparing aqueous phase cdse@zns quantum dots suitable for a carrier-free injection light emitting diode according to claim 1, wherein in step 1, the amount of the cadmium acetate substance is 0.01-0.1 times the amount of the oleic acid substance, the amount of the zinc oxide substance is 0.1-0.2 times the amount of the oleic acid substance, the volume of the octadecene is 2-3.5 times the volume of the oleic acid, the first temperature is 140-160 ℃, and the second temperature is 280-320 ℃.
  3. 3. The method for preparing aqueous phase cdse@zns quantum dots suitable for a carrier-free light emitting diode according to claim 1, wherein in step 2, the amount of the substance of sulfur powder is 0.4 to 0.5 times the amount of the substance of tri-n-octylphosphine, the amount of the substance of selenium powder is 0.4 to 0.5 times the amount of the substance of tri-n-octylphosphine, and the third temperature is 50 to 70 ℃.
  4. 4. The method for preparing aqueous phase cdse@zns quantum dots suitable for a carrier-free light emitting diode according to claim 1, wherein in step 3, the volume of the selenium-sulfur precursor solution used is 0.08-0.12 times that of the cadmium-zinc precursor solution, and the second temperature maintaining time is 10-25 minutes.
  5. 5. The method for preparing aqueous phase cdse@zns quantum dots suitable for a light emitting diode without carrier injection according to claim 1, wherein in step 4, the concentration of the nonpolar phase cdse@zns quantum dots is 4-6mg/mL.
  6. 6. The method for preparing the aqueous phase CdSe@ZnS quantum dot suitable for a carrier-free injection light emitting diode according to claim 1, wherein in the step 5, the short-chain amino acid ligand comprises any one or more of glutathione, histidine and cysteine, the concentration of the amino acid ligand solution is 0.3-1.0mol/L, the concentration of the added sodium hydroxide solution is 0.8-1.2mol/L, the pH value of a system after the sodium hydroxide solution is added is 12.0-13.5, the concentration of the added zinc chloride solution is 0.2-0.3mol/L, the volume of the added zinc chloride solution is 0.5-0.7 times the volume of the amino acid ligand solution, the concentration of the added thiourea solution is 0.2-0.3mol/L, and the volume of the added thiourea solution is 0.5-0.7 times the volume of the amino acid ligand solution.
  7. 7. The method for preparing aqueous phase cdse@zns quantum dots suitable for a carrier-free light emitting diode according to claim 1, wherein in step 6, the volume of the nonpolar cdse@zns quantum dot solution used is 0.3-0.4 times the volume of the aqueous phase solution, and the two-phase stirring time is 4-6 hours.
  8. 8. The aqueous phase CdSe@ZnS quantum dot suitable for the carrier-free injection light emitting diode is characterized by comprising a light emitting core and a surface ligand positioned on the surface of the light emitting core, wherein the light emitting core comprises oil-soluble CdSe@ZnS quantum dots, the surface ligand comprises a short chain amino acid ligand, and the short chain amino acid ligand comprises any one or a combination of more of glutathione, histidine and cysteine.
  9. 9. A carrier-free injection light emitting diode comprising: an anode, an insulating layer, a quantum dot light-emitting layer and a cathode which are sequentially stacked, wherein the material of the quantum dot light-emitting layer comprises the aqueous phase CdSe@ZnS quantum dot suitable for the light-emitting diode without carrier injection as claimed in claim 8.
  10. 10. The carrier-free injection light emitting diode of claim 9, further comprising: a first functional layer disposed between the insulating layer and the quantum dot light emitting layer; the first functional layer comprises at least one of a hole injection layer and a hole transport layer; and/or the number of the groups of groups, The second functional layer comprises at least one of an electron injection layer and an electron transport layer; wherein the material of the anode comprises indium tin oxide, or the material of the insulating layer comprises PMMA, or the material of the hole injection layer comprises PEDOT: PSS, or the material of the hole transport layer comprises TFB, or the material of the electron transport layer comprises TPBI, or the material of the electron injection layer comprises LiF, or the material of the cathode comprises an Al film.

Description

Aqueous phase CdSe@ZnS quantum dot suitable for light-emitting diode without carrier injection, preparation method thereof and light-emitting diode without carrier injection Technical Field The application relates to the technical field of preparation of novel nano optoelectronic materials, in particular to a water phase CdSe@ZnS quantum dot suitable for a carrier-free injection electroluminescent device, a preparation method thereof and a preparation method of a carrier-free injection light-emitting diode. Background The carrier-free injection type light-emitting diode is expected to be applied to novel Micro display technologies such as Micro-LEDs, nano pixel luminous display and the like due to a simple device structure, and has wide application prospects in the field of photoelectric devices. In the device structure of the carrier-free injection type light emitting diode, the light emitting layer is generally in contact with the insulating layer or the functional layer based on the polar phase, and the insulating layer or the functional layer are generally hydrophilic, so that it is necessary to introduce an appropriate light emitting layer. The quantum dots are very important nano materials, have the advantages of narrow half-width, adjustable emission wavelength, high color purity and the like, and are also widely focused in the novel display field. The traditional quantum dot synthesis method often faces different challenges such as limited wavelength regulation range, low quantum yield, poor water solubility and the like, and in order to promote uniform spreading of a luminescent layer on an insulating layer of a device, a strategy for synthesizing polar phase quantum dots efficiently and flexibly is needed. Disclosure of Invention The invention can provide the aqueous phase CdSe@ZnS quantum dot suitable for the non-injection device and the synthesis method thereof aiming at the unique structure of the non-carrier injection type light-emitting diode. The CdSe@ZnS in the oil phase is subjected to surface modification by utilizing a water-soluble short-chain amino acid ligand, so that the phase state of the CdSe@ZnS in the oil phase can be transferred to the water phase on the premise of not obviously reducing the luminous performance of the CdSe@ZnS, the uniform spreading of the luminous layer on the device insulating layer or the functional layer can be effectively improved, and the electroluminescent performance of the CdSe@ZnS quantum dot without carrier injection is improved. The invention provides an aqueous phase CdSe@ZnS quantum dot suitable for a carrier-free injection light emitting diode, which comprises a light emitting core and a surface ligand positioned on the surface of the light emitting core, wherein the light emitting core comprises an oil-soluble CdSe@ZnS quantum dot, the surface ligand comprises a short chain amino acid ligand, and the short chain amino acid ligand comprises any one or a combination of more of glutathione, histidine and cysteine. The invention provides a preparation method of aqueous phase CdSe@ZnS quantum dots suitable for a carrier-free injection light-emitting diode, which comprises the following steps: Step 1, adding cadmium acetate and zinc oxide into oleic acid for reaction, heating a reaction system to a first temperature, carrying out degassing reaction at the first temperature, and then adding octadecene to heat to a second temperature to obtain a cadmium-zinc precursor liquid; Step 2, adding sulfur powder and selenium powder into tri-n-octyl phosphine for reaction, and heating the reaction system to a third temperature to obtain selenium-sulfur precursor liquid; Step 3, injecting the reaction product obtained in the step 2 into the reaction product obtained in the step 1, maintaining the reaction system at a second temperature for a period of time, and then cooling to room temperature; Step 4, washing the CdSe@ZnS quantum dots obtained in the step 3 by using a mixed solution of normal hexane and acetone, and dispersing the washed CdSe@ZnS quantum dots in a nonpolar solvent chloroform; step 5, dissolving the short-chain amino acid ligand in water, and sequentially adding sodium hydroxide solution, zinc chloride solution and thiourea solution; And 6, adding the aqueous phase solution obtained in the step 5 into the nonpolar CdSe@ZnS quantum dots obtained in the step 4, and stirring to obtain a crude product of the aqueous phase CdSe@ZnS quantum dots. And 7, washing the aqueous phase CdSe@ZnS quantum dot crude product obtained in the step 6 with ethanol, and redispersing in deionized water to obtain the aqueous phase CdSe@ZnS quantum dot suitable for the light-emitting diode without carrier injection. And 8, the carrier-free injection light-emitting diode comprises a glass substrate, and a cathode, an insulating layer, a hole injection layer, a hole transport layer and a quantum dot light-emitting layer sequentially arranged on the glass substrate, wherein