CN111088045A

CN111088045A - Method for preparing high-performance perovskite quantum dots based on mercaptosilane ligand exchange

Info

Publication number: CN111088045A
Application number: CN201911395343.1A
Authority: CN
Inventors: 王向华; 徐志梁; 陈幸福
Original assignee: Shanghai Biying Semiconductor Technology Co Ltd
Current assignee: Shanghai Biying Semiconductor Technology Co Ltd
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2020-05-01
Anticipated expiration: 2039-12-30
Also published as: CN111088045B

Abstract

The invention discloses a method for preparing a high-performance perovskite quantum dot based on mercaptosilane ligand exchange, which is characterized in that 3-mercaptopropyltrimethoxysilane is used as a new surface ligand to replace the original surface ligands oleylamine and oleic acid of the perovskite quantum dot, so that the high-performance perovskite quantum dot is obtained. The method can simply and effectively improve the fluorescence quantum efficiency and the solution processing performance of the perovskite quantum dots.

Description

Method for preparing high-performance perovskite quantum dots based on mercaptosilane ligand exchange

Technical Field

The invention belongs to the field of semiconductor materials, and particularly relates to a perovskite quantum dot material with surface passivation by adopting mercaptosilane.

Background

The inorganic perovskite quantum dot is a nano material formed by ionic bond combination, in particular CsPbBr₃The nano crystal has the advantages of good stability, high fluorescence quantum efficiency, narrow emission spectrum half-peak width and the like. The preparation method of the high-performance inorganic perovskite nanocrystalline is mainly a high-temperature thermal injection method, and comprises the steps of adopting a non-polar solvent octadecene, taking long-chain oleylamine and oleic acid as ligands, quickly and uniformly mixing cesium oleate and a lead chloride solution under a high-temperature condition, and after a quick nucleation growth process, placing a reactor in an ice water bath for quick cooling to form quantum dots. The product is washed, centrifugally separated and dispersed in non-polar solvent such as n-hexane, toluene or heptane. The quantum dot product obtained by the method has rapid degradation of optical performance in a polar solvent environment with high dielectric constant, so that only a solvent with lower dielectric constant can be adoptedCleaning or preparing films^[1]. Due to the limitation of the polarity of the solvent, the materials are difficult to form mixed dispersion with other materials, thereby limiting the application of the materials in terms of technology. In addition, the combination of oleylamine and oleic acid with the surface of the nanocrystal is weak, the thermal stability is poor, the oleylamine and oleic acid are easy to fall off under the heating or illumination condition, the optical performance of the quantum dot is attenuated, and the service life of a corresponding device is short.

Reference documents:

[1]Chiba,T.,et al.(2018)."Anion-exchange red perovskite quantum dotswith ammonium iodine salts for highly efficient light-emitting devices."Nature Photonics 12(11):681-687.

disclosure of Invention

Based on the defects of the prior art, the invention discloses a method for preparing high-performance perovskite quantum dots based on mercaptosilane ligand exchange, so that the high-performance perovskite quantum dots with higher fluorescence quantum efficiency and better solution processability can be obtained.

In order to realize the purpose of the invention, the following technical scheme is adopted:

the invention relates to a method for preparing high-performance perovskite quantum dots based on mercaptosilane ligand exchange, which is characterized by comprising the following steps: adding 3-mercaptopropyltrimethoxysilane MPTMS into a dispersion liquid of a non-polar solvent of the perovskite quantum dots, which is prepared by taking oleylamine and oleic acid as surface ligands through a thermal injection method, stirring for reaction, and enabling the MPTMS to serve as a new surface ligand to replace an original surface ligand, thereby obtaining the high-performance perovskite quantum dots.

In the method, the MPTMS forms stable Pb-S covalent bond combination with lead atoms on the surface of the perovskite quantum dot through sulfydryl, so that the fluorescence quantum efficiency and the solution processability of the perovskite quantum dot are improved.

Further, the perovskite quantum dot is CsPbBr₃And (4) quantum dots.

Further, the mass ratio of the perovskite quantum dots to the MPTMS is 1.2-2: 1.

Further, the stirring reaction is carried out for 12 hours under the condition of normal temperature.

Compared with the prior art, the invention has the beneficial effects that:

1. the method provided by the invention simply and effectively improves the fluorescence quantum efficiency of the perovskite quantum dots, and improves the surface chemical stability of the quantum dots, and the contrast experiment proves that the fluorescence quantum efficiency of the quantum dots after ligand exchange can reach 95%, and is improved by about 35-45% compared with that before ligand exchange.

2. After the surface ligand exchange, the surface polarity of the quantum dots is changed, the obtained quantum dots can be mutually dissolved with a polar solvent, the fluorescence quantum efficiency is further improved, and the solution processability is better.

Drawings

FIG. 1 shows MP-CsPbBr₃Quantum dot dispersion liquid and MP-CsPbBr diluted by p-xylene₃An absorption spectrum of the quantum dot dispersion;

FIG. 2 shows MP-CsPbBr₃Quantum dot dispersion liquid and MP-CsPbBr diluted by p-xylene₃PL spectrum of quantum dot dispersion;

FIG. 3 shows CsPbBr before ligand exchange₃Quantum dot dispersion (untreated control), MP-CsPbBr after ligand exchange₃Quantum dot dispersion (MP-QD) and MP-CsPbBr after dilution of paraxylene₃PLQY vs. plot of quantum dot dispersion (p-xylene diluted MP-QD).

Detailed Description

The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.

Example 1

This example prepares MP-CsPbBr as follows₃Quantum dot:

(1) preparation of cesium oleate

0.319g of Cs₂CO₃Adding into 15mL ODE solution, adding 1.5mL oleic acid, introducing nitrogen, heating and stirring at 150 deg.C until Cs₂CO₃The mixture is completely dissolved and dissolved in the solvent,a cesium oleate solution is obtained, preheated at 100 ℃ before use.

(2)CsPbBr₃Preparation of Quantum dot Dispersion

0.2g of PbBr was added₂Adding into 20mL ODE solution, vacuum drying at 100 deg.C for 20min, adding 2mL oleic acid and 2mL oleylamine, stirring to PbBr₂Completely dissolving; then heating to 165 ℃, quickly injecting 2mL of cesium oleate solution, reacting for 10s, quickly cooling in an ice-water bath for 1min, adding 2 times of ethyl acetate, centrifuging for 5min at the rotating speed of 8000rpm, dispersing the obtained precipitate in 5mL of non-polar solvent n-heptane, centrifuging for 3min at the rotating speed of 5000rpm, and separating the obtained supernatant, namely CsPbBr₃A quantum dot dispersion.

(3)MP-CsPbBr₃Preparation of

CsPbBr at 5mL concentration of 15mg/mL₃Adding 50 μ L MPTMS into the quantum dot dispersion liquid, stirring at 1000rpm at normal temperature for 12h, centrifuging at 5000rpm for 3min to obtain supernatant as MP-CsPbBr₃And the concentration of the quantum dot dispersion liquid is 24 mg/mL.

To verify the obtained MP-CsPbBr₃The stability of the quantum dots in different solvents is realized, and the obtained MP-CsPbBr is used₃The quantum dot dispersion liquid is diluted to the concentration of 12mg/mL by paraxylene, and the obtained dispersion liquid becomes clearer, so that the method provided by the invention improves the dispersibility of the quantum dots. And CsPbBr without MPTMS treatment₃The quantum dots cannot be stably dispersed in the mixed solvent of p-xylene. Although p-xylene is a non-polar solvent, it has a higher dielectric constant than heptane, i.e., it is relatively polar. Paraxylene is an excellent solvent of organic micromolecules, can be mutually soluble with heptane or hexane with lower dielectric constant and can also be mutually soluble with a solvent with higher dielectric constant, so that the solution processing performance of the material is greatly improved when the dispersion liquid is used as the perovskite quantum dot dispersion liquid.

FIG. 1 and FIG. 2 show MP-CsPbBr₃Quantum dot dispersion liquid and MP-CsPbBr diluted by p-xylene₃An absorption spectrum and a PL spectrum of the quantum dot dispersion. It can be seen that the PL half-peak width (FWHM) of the quantum dots was 24nm before and after dilution without any change.

High PLQY forThe application of perovskite quantum dots is critical. For quantum dot emitters, a high PLQY produces brighter emission at the same input energy. For quantum dot absorbers in solar cells, higher PLQY will result in higher open circuit voltages and greater energy conversion efficiency. By integrating sphere method (the main testing equipment is a Horiba FluoroMax-4 high-sensitivity integrated fluorescence spectrometer, and the configured integrating sphere is Horiba Quanta-

) Detection of CsPbBr before ligand exchange at 365nm excitation wavelength₃Quantum dot dispersion liquid and MP-CsPbBr after ligand exchange₃Quantum dot dispersion and MP-CsPbBr diluted by paraxylene₃PLQY of quantum dot dispersion. The results are shown in figure 3. It can be seen that CsPbBr was present before exchange with ligand₃Quantum dots (PLQY 65.26% only) MP-CsPbBr after surface ligand exchange by MPTMS₃The PLQY of the quantum dots is improved to 89.18%, and the quantum dots are diluted by p-xylene to obtain MP-CsPbBr₃The PLQY of the quantum dots is further improved to 95.63 percent.

The above examples fully demonstrate that CsPbBr can be significantly improved by the simple surface ligand exchange method₃The fluorescence quantum efficiency and solution processibility of quantum dots.

The above description is only exemplary of the present invention and should not be taken as limiting the invention, and any modifications, equivalents, improvements and the like that are within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The method for preparing the high-performance perovskite quantum dot based on mercaptosilane ligand exchange is characterized by comprising the following steps of: adding 3-mercaptopropyltrimethoxysilane MPTMS into a dispersion liquid of a non-polar solvent of the perovskite quantum dots, which is prepared by taking oleylamine and oleic acid as surface ligands through a thermal injection method, stirring for reaction, and enabling the MPTMS to serve as a new surface ligand to replace an original surface ligand, thereby obtaining the high-performance perovskite quantum dots.

2. The method of claim 1, wherein: the MPTMS forms stable Pb-S covalent bond combination with lead atoms on the surface of the perovskite quantum dot through sulfydryl, so that the fluorescence quantum efficiency and the solution processability of the perovskite quantum dot are improved.

3. The method according to claim 1 or 2, characterized in that: the perovskite quantum dot is CsPbBr₃And (4) quantum dots.

4. The method according to claim 1 or 2, characterized in that: the mass ratio of the perovskite quantum dots to the MPTMS is 1.2-2: 1.

5. The method according to claim 1 or 2, characterized in that: the stirring reaction is carried out for 12 hours under the condition of normal temperature.