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CN-121991682-A - CdSe/ZnS quantum dot based on ligand stabilization of multiple binding sites, preparation method thereof and carrier-free injection LED device

CN121991682ACN 121991682 ACN121991682 ACN 121991682ACN-121991682-A

Abstract

The application provides a CdSe/ZnS quantum dot based on ligand stabilization of multiple binding sites, a preparation method thereof and an LED device without carrier injection. According to the scheme, the alanine modified long-chain alkylamine ligand is used, wherein the alanine endows the ligand with more sites which are mutually combined with the surface of the quantum dot, more combining sites can passivate the surface defects of the CdSe/ZnS quantum dot and improve the luminous efficiency, and the stability of the quantum dot can be improved, so that the prepared modified quantum dot can be applied to a non-injection electroluminescent device driven by a high-frequency alternating current electric field.

Inventors

  • XIAO YIN
  • CAO RUI

Assignees

  • 天津大学

Dates

Publication Date
20260508
Application Date
20241106

Claims (10)

  1. 1. The preparation method of the CdSe/ZnS quantum dot based on ligand stabilization of multiple binding sites is characterized by comprising the following steps: step 1, adding N-t-butoxycarbonyl-alanine and long-chain alkylamine into methylene dichloride for reaction, and removing a protecting group from the obtained reaction product under trifluoroacetic acid to obtain a ligand with multiple binding sites; Step 2, mixing selenium powder with tri-n-octyl phosphine, and carrying out a degassing reaction to obtain a first precursor liquid; Step 3, adding cadmium oxide and oleic acid into octadecene, heating under an inert gas atmosphere to dissolve the cadmium oxide, then adding oleylamine, and heating to raise the temperature to obtain a second precursor liquid; step 4, injecting the first precursor liquid obtained in the step 2 into the second precursor liquid obtained in the step 3, and reacting to obtain CdSe quantum dot solution; and 5, heating the CdSe quantum dot solution obtained in the step 4, and then adding zinc diethyl dithiocarbamate and the ligand with multiple binding sites obtained in the step 1, and reacting to obtain the CdSe/ZnS quantum dot with stable ligand based on multiple binding sites.
  2. 2. The method for preparing CdSe/ZnS quantum dots based on ligand stabilization of multiple binding sites according to claim 1, wherein the long-chain alkylamine in step 1 is a long-chain amine having 14 or more carbon atoms.
  3. 3. The method for preparing the CdSe/ZnS quantum dot based on ligand stabilization of multiple binding sites according to claim 1, wherein the tri-n-octylphosphine in the step 2 is 2.8-3.0 times of the selenium powder.
  4. 4. The method for preparing the CdSe/ZnS quantum dot based on ligand stabilization of multiple binding sites according to claim 1, wherein oleic acid in the step 3 is 0.18-0.20 times of the volume of the octadecene solvent, cadmium oxide is 0.10-0.12 times of the volume of oleic acid, and oleylamine is 0.80-0.90 times of the volume of the octadecene solvent.
  5. 5. The method for preparing the CdSe/ZnS quantum dot based on ligand stabilization of multiple binding sites according to claim 1, wherein the volume of the first precursor solution in the step 4 is 0.10 to 0.12 times the volume of the second precursor solution.
  6. 6. The method for preparing the CdSe/ZnS quantum dot based on multi-binding site ligand stabilization according to claim 1, wherein in the step 5, the amount of the multi-binding site ligand is 0.06-0.07 times the amount of the substance of octadecene solvent, and the amount of zinc diethyldithiocarbamate is 0.32-0.35 times the amount of the substance of the multi-binding site ligand.
  7. 7. A CdSe/ZnS quantum dot stabilized by a ligand based on multiple binding sites, wherein the CdSe/ZnS quantum dot stabilized by a ligand based on multiple binding sites is prepared by the method of any one of claims 1 to 6.
  8. 8. A no-carrier injection LED device, 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 CdSe/ZnS quantum dot based on multi-junction-site ligand stabilization as claimed in claim 7.
  9. 9. The carrier-free injection LED device of claim 8, 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, And the second functional layer comprises at least one of an electron injection layer and an electron transport layer.
  10. 10. The carrier-free injection LED device of claim 9, 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 includes TPBI; Or the material of the electron injection layer comprises LiF; or the material of the cathode includes an Al film.

Description

CdSe/ZnS quantum dot based on ligand stabilization of multiple binding sites, preparation method thereof and carrier-free injection LED device Technical Field The invention relates to a CdSe/ZnS quantum dot based on ligand stabilization of multiple junction sites and a preparation method of an injection-free device thereof, belonging to the field of preparation of novel nano optoelectronic materials. Background Conventional dc-driven LEDs have problems in micro-nano displays (micro-displays and nano-displays). An injection-free LED (i.e., a carrier-free injection LED) refers to a light emitting device with an insulator/QD (quantum dot)/insulator structure driven by a high frequency alternating field, which is composed of an insulating layer and an emitting layer, does not require precise design of energy band matching, and has application advantages in large-scale, flexible, stretchable and micro-nano displays. The non-injection LED is electroluminescence driven by high frequency and high alternating voltage, and the high frequency alternating electric field easily drops the ligand on the surface of the quantum dot, so that the luminous performance of the device is reduced. In view of this, there is a need to effectively enhance the binding of ligands to the CdSe/ZnS quantum dot surface, improving the performance and stability of the device. Disclosure of Invention The invention aims at the limitation of the prior art, and provides a CdSe/ZnS quantum dot based on ligand stabilization of multiple binding sites, a preparation method thereof and a preparation method of an injection-free device applying the quantum dot. The alanine is used for modifying the long-chain alkylamine, so that the obtained novel amine ligand has more action sites on the surface of the CdSe/ZnS quantum dot, the mutual combination of the ligand and the surface of the quantum dot can be enhanced, more binding sites can passivate the surface defects of the CdSe/ZnS quantum dot and improve the luminous efficiency, and the stability of the quantum dot can be improved, so that the prepared modified quantum dot can be applied to a non-injection electroluminescent device driven by a high-frequency alternating current electric field. . According to the invention, a heat injection method is used, and alanine modified long-chain alkylamine is used as a ligand of a multiple binding site, so that the CdSe/ZnS quantum dot with good luminescence and stability is synthesized. The method is simple and quick, and has universality. The invention provides a preparation method of CdSe/ZnS quantum dots based on ligand stabilization of multiple binding sites, which comprises the following steps: Step 1, reacting N-t-butoxycarbonyl-alanine with long-chain alkylamine in dichloromethane, and removing a protecting group from the obtained reaction product under trifluoroacetic acid to obtain the ligand with multiple binding sites. Step 2, mixing selenium powder with tri-n-octyl phosphine, and carrying out degassing reaction at 50-80 ℃ and preferably at 60 ℃ to obtain a first precursor liquid. And 3, heating cadmium oxide, oleic acid and a solvent octadecene to 180-210 ℃ under an argon atmosphere (preferably, heating to 210 ℃) to dissolve the cadmium oxide, then adding oleylamine, and heating to 250-270 ℃ (preferably, heating to 270 ℃) to obtain a second precursor liquid. And 4, injecting a certain amount of the first precursor liquid obtained in the step 2 into the second precursor liquid obtained in the step 3, reacting 25-35 min (preferably, reacting 25 min) and then cooling to obtain the CdSe quantum dot solution. And 5, heating the CdSe quantum dot obtained in the step 4 to 160-180 ℃, then adding zinc diethyl dithiocarbamate and the multi-binding site amine ligand, reacting 10-20 min (preferably, 10-min can be reacted), and cooling and purifying to obtain the CdSe/ZnS quantum dot with stable multi-binding site ligand. Further, the long-chain alkylamine in the step 1 is long-chain amine with carbon number more than fourteen. Further, the tri-n-octyl phosphine in the step 2 is 2.8-3.0 times of the selenium powder. Further, the oleic acid in the step 3 is 0.18-0.20 times of the volume of the octadecene solvent. Further, the amount of the substance of which the cadmium oxide is oleic acid in the step 3 is 0.10-0.12 times of the amount of the substance. Further, the oleylamine in the step 3 is 0.80-0.90 times of the volume of the octadecene solvent. Further, the volume of the first precursor solution injected in the step 4 is 0.10-0.12 times of the volume of the second precursor solution. Further, the amount of the ligand of the multiple binding site in the step 5 is 2.9-3.1 times of the amount of the zinc diethyl dithiocarbamate. Further, the amount of the ligand at the multiple binding site in the step 5 is 0.06-0.07 times of the amount of the octadecene solvent substance. The embodiment of the invention provides a CdSe/ZnS quantum dot based on ligand stabiliza