CN109932379B - Method for measuring content of ligand on surface of quantum dot and method for preparing quantum dot ink - Google Patents
Method for measuring content of ligand on surface of quantum dot and method for preparing quantum dot ink Download PDFInfo
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Abstract
The invention provides a method for measuring the content of a ligand on the surface of a quantum dot and a method for preparing quantum dot ink. The method for preparing the quantum dot ink can ensure the uniformity of the quality of the quantum dot ink, ensure the solubility, the drying rate and the coffee ring effect of quantum dot ink in different batches to be the same, and improve the uniformity of the pixel resolution, the turn-on voltage and the photoelectric efficiency of the quantum dot display panel.
Description
Technical Field
The invention relates to the technical field of quantum dot ink, in particular to a method for measuring the content of a ligand on the surface of a quantum dot and a method for preparing the quantum dot ink.
Background
Quantum dots, refers to semiconductor nanocrystals whose geometric dimensions are smaller than the exciton bohr radius. The quantum dots have excellent optical properties such as wide absorption band, narrow fluorescence emission band, high quantum efficiency, good light stability and the like, and have great potential application in the fields of biomedicine, environmental energy, illumination display and the like. In recent years, the display technology based on quantum dot light emission receives high attention from the display industry, and compared with liquid crystal display and organic light emitting display, quantum dot light emission has the advantages of wider color gamut, higher color purity, simpler structure and higher stability, and is considered as a new generation display technology.
The preparation technology of the quantum dot display device comprises spraying, ink-jet printing, slit coating, gravure printing, screen printing and the like. The specific process of the ink-jet printing is that quantum dot ink is sprayed on a printing stock and forms a quantum dot film at a specific position after being dried. Compared with other preparation technologies, the ink-jet printing has the characteristics of low cost, convenience, high printing quality, suitability for manufacturing large-size panels and the like. The preparation of the quantum dot ink is to dissolve quantum dots in a specific solvent to form a solution with certain viscosity, surface tension and charge transport capacity. The viscosity, surface tension and charge transport capacity of the quantum dot ink determine the wetting capacity, drying rate, coffee ring effect and photoelectric properties of the film of ink droplets during ink-jet printing, and therefore, the quality of the quantum dot ink plays a crucial role in the ink-jet printing effect. In the process of preparing the quantum dot ink, the surface ligand of the quantum dot has an important influence on the quantum dot ink, so that the photoelectric property of the quantum dot is influenced, and the solubility and the stability of the quantum dot ink are also influenced. Common surface ligands are carboxylic acids, amines, alkyl phosphorus, alkyl phosphine oxides, alkyl phosphoric acids, thiols, and the like. The influence of the surface ligand on the optical performance of the quantum dot per se is shown as follows: the size of the quantum dot is smaller than the bohr radius of the exciton, the exciton is exposed on the surface to a certain extent, and the surface is easily influenced to reduce the optical performance of the exciton; when the surface atomic number of the quantum dot is increased, the surface dangling bonds are also increased rapidly, the surface of the quantum dot has many defects due to insufficient atom coordination, the probability of non-radiative recombination is increased due to the existence of the defects such as electrons or holes, and the recombination efficiency of normal radiative recombination is greatly reduced. When a proper surface ligand is added, the surface dangling bonds of the quantum dots can be effectively reduced, excitons are not exposed on the surface any more, and the optical performance of the quantum dots is improved. The influence of the surface ligand on the solubility and stability of the quantum dot is shown as follows: the increase of dangling bonds on the surface of the quantum dot leads the surface free energy to be very large, the surface becomes abnormally active, the system is unstable, the quantum dot tends to aggregate to reduce the surface area, and the solubility of the quantum dot solution is reduced. After the surface ligand is introduced, one end of the ligand is connected to the surface atoms of the quantum dots, and the other end of the ligand is dissolved in the solution, so that the surface energy of the quantum dots can be reduced, the solubility of the quantum dots can be improved, and the generation of precipitation in the quantum dot solution can be effectively inhibited.
In the current quantum dot ink-jet printing process, a common problem exists, that is, the properties of inks prepared by the same process and different batches of the same quantum dots under the same ink formula condition are different, and the reason for the difference is mainly caused by the difference of the ligand exchange rates on the surfaces of the quantum dots. If the amount of the ligand on the surface of the quantum dot is too small, the quantum dot is not easily dissolved in the ink solvent, and thus ink jet printing cannot be performed. If the quantum dot surface ligand exchange rates of different batches are different, the solubility, drying rate and coffee ring effect of the quantum dot ink are different, so that the quality of a luminescent layer film is affected, and the problems of uneven quality of a printed panel, low pixel resolution, uneven lighting voltage, uneven photoelectric efficiency and the like are directly caused.
Disclosure of Invention
In view of the defects of the prior art, in order to ensure the quality stability of the quantum dot ink, the invention firstly provides a method for measuring the content of the ligand on the surface of the quantum dot, and further provides a method for preparing the quantum dot ink.
A method for measuring the content of a ligand on the surface of a quantum dot comprises the following steps:
providing sample particles, wherein each particle in the sample particles comprises a quantum dot and a phosphorus-containing organic ligand bound on the surface of the quantum dot, the quantum dot does not contain phosphorus element, the organic ligands are one or more, and when the organic ligands are multiple, the molar molecular mass of each organic ligand is different from that of each other by no more than 5%;
and (3) measuring the mass percentage of the P element in the organic ligand in the sample particles by using a nuclear magnetic resonance analyzer, and calculating the mass percentage as the content of the ligand on the surface of the quantum dot.
The method for measuring the content of the ligand on the surface of the particle is simple, has strong operability, can be used for evaluating the synthesis quality of quantum dots in different batches, and particularly provides reliable guarantee for guaranteeing the quality of quantum dots synthesized in different batches in the same preparation process.
The invention also provides a configuration method of quantum dot ink, which comprises the following steps:
providing sample particles, wherein each particle in the sample particles comprises a quantum dot and organic ligands containing phosphorus, wherein the organic ligands are bound on the surface of the quantum dot, the quantum dot does not contain phosphorus, the organic ligands are the same or different, and when the organic ligands are different, the molar molecular mass of each organic ligand is different by no more than 5%;
respectively measuring the surface ligand content of different batches of the sample particles according to the method for measuring the particle surface ligand content;
selecting one batch of sample particles as a reference batch of sample particles;
when the surface ligand content of other batch of sample particles is different from the surface ligand content of the reference batch of particles by no more than 10%, using the other batch of sample particles for configuring ink;
when the surface ligand content of other batch of sample particles is different from the surface ligand content of the reference batch of particles by more than 10%, adjusting the surface ligand content of the other batch of particles to be within 10% of the surface ligand content of the reference batch of particles, and then using the other batch of particles after adjusting the surface ligand content for configuring ink.
In order to ensure the stability of the quantum dot ink, the invention provides a preparation method of the quantum dot ink. Specifically, aiming at the same quantum dots of different batches, determining the content of the organic ligand on the surface of the reference sample particle by a nuclear magnetic resonance analysis method and recording the content as omega1Determining the surface ligand content omega of other sample particles prepared from different batches (for example, other sample particles obtained based on the same method or the same preparation process)2If ω is2=【90%ω1, 110%ω1The content of the ligand on the surface of the quantum dots of the sample particles in batches is consistent, and the preparation of the quantum dot ink can be carried out; if omega2<90%ω1Regulation of omega by ligand-exchange2To 90% omega1~110%ω1Then preparing quantum dot ink; if omega2>110%ω1Firstly, the omega is adjusted by adopting a ligand removal method2To 90% omega1~110%ω1And preparing the quantum dot ink. The method for preparing the quantum dot ink can ensure the uniformity of the quality of the quantum dot ink, ensure the solubility, the drying rate and the coffee ring effect of quantum dot ink in different batches to be the same, and improve the uniformity of the pixel resolution, the turn-on voltage and the photoelectric efficiency of the quantum dot display panel.
Detailed Description
The present invention provides a method for measuring the content of a ligand on the surface of a particle, and the present invention is further described in detail below in order to make the object, technical scheme and effect of the present invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
A method for measuring the content of a ligand on the surface of a quantum dot comprises the following steps:
s10 providing sample particles, wherein individual particles in the sample particles comprise quantum dots and phosphorus-containing organic ligands bound to the surfaces of the quantum dots, the quantum dots do not contain phosphorus element, the organic ligands are the same or different, and when the organic ligands are different, the molar molecular mass of each organic ligand is different by no more than 5%;
s20, measuring the mass percentage of P element in the organic ligand in the sample particles by using a nuclear magnetic resonance analyzer, and calculating the mass percentage as the content of the ligand on the surface of the quantum dot.
The quantum dot comprises a known quantum dot A, wherein the quantum dot A comprises a unary, binary, ternary and quaternary quantum dot.
Specifically, in step S10, the quantum dots may be selected from unary quantum dots, binary quantum dots, ternary quantum dots, or quaternary quantum dots. For example: the unitary quantum dots are selected from Au, Ag, Cu, Pt or C quantum dots; the binary quantum dots are selected from CdSe, ZnSe, PbSe, CdTe, ZnO, MgO and CeO2、NiO、TiO2InP or CaF2Quantum dots; the ternary quantum dots are selected from CdZnS, CdZnSe, CdSeS, PbSeS, ZnCdTe, CdS/ZnS, CdZnS/ZnS, CdZnSe/ZnSe, CdSeS/CdSeS/CdS, CdSe/CdZnSe/CdZnSe/ZnSe, CdS/CdZnS/CdZnS/ZnS, NaYF4Or NaCdF4Quantum dots; the quaternary quantum dots comprise CdSZnSeyS, CdSe/ZnS, CdSe/CdS/ZnS, CdSe/ZnSe/ZnS, CdSZnSe/CdS/ZnS or InP/ZnS quantum dots.
Specifically, in step S10, the phosphorus-containing organic ligand is selected from alkyl phosphorus, alkyl phosphine oxide or alkyl phosphoric acid. Preferably, the alkyl phosphine is selected from the group consisting of tributylphosphine, tripentylphosphine, trihexylphosphine, trimore-ylphosphine, trioctylphosphine, trinonyl phosphine, and tridecyl phosphine, but is not limited thereto; preferably, the alkyl phosphine oxide is selected from the group consisting of tributyl phosphine oxide, tripentyl phosphine oxide, trihexyl phosphine oxide, triheptyl phosphine oxide, trioctyl phosphine oxide, trinonyl phosphine oxide and tridecyl phosphine oxide, but not limited thereto; preferably, the alkyl phosphoric acid is selected from alkyl phosphoric acids having more than 8 carbon atoms, such as, but not limited to, dodecyl phosphoric acid, undecyl phosphoric acid, dodecyl phosphoric acid, tridecyl phosphoric acid, tetradecyl phosphoric acid, pentadecyl phosphoric acid, hexadecyl phosphoric acid, or octadecyl phosphoric acid.
Specifically, the step S20 includes the following steps:
s201, providing an internal standard solution, wherein a solvent of the internal standard solution is deuterated chloroform, and obtaining a PNMR curve of the internal standard solution by using nuclear magnetic resonance equipment;
s202, providing a sample particle solution, wherein a solvent of the sample particle solution is deuterated chloroform, adding the internal standard solution into the sample particle solution to prepare a solution to be detected, and obtaining a PNMR curve of the solution to be detected by using nuclear magnetic resonance equipment;
s203, performing integral operation according to the PNMR curve of the internal standard substance solution and the PNMR curve of the solution to be detected, calculating to obtain the concentration of the P element in the sample particle solution, and converting to obtain the mass percentage content of the P element in the organic ligand in the sample particles, wherein the mass percentage content is counted as the content of the quantum dot surface ligand.
According to the PNMR nuclear magnetic resonance analysis method, according to an internal standard substance solution PNMR curve (phosphorus nuclear magnetic resonance spectral line) with known concentration, the internal standard solution is added into the sample particle solution to prepare a solution to be detected, and a nuclear magnetic resonance device is used for obtaining the PNMR curve of the solution to be detected. And performing integral operation according to the internal standard substance solution PNMR curve and the to-be-detected solution PNMR curve, and calculating to obtain the concentration of the P element in the sample particle solution, so that the calculated mass percentage content of the P element in the sample particle is calculated, wherein the P element only exists in the organic ligands, and the organic ligands are one or more, and when the organic ligands are multiple, the molar molecular mass difference between the organic ligands is not more than 5%. The mass percentage content of the P element can be used as the content of the surface ligand of the quantum dot.
In step S20, the internal standard solution and the sample particle solution are respectively placed in a nuclear magnetic resonance device, the operating frequency of the nuclear magnetic resonance device is adjusted to be 150-200MHz, the testing temperature is 275-325K, and the spectrum width of the PNMR is 64-102Hz, so as to obtain the PNMR curve of the internal standard solution and the NMR curve of the sample particle solution through testing. Preferably, a baseline scan is performed with the internal standard prior to the sample particle solution test. Respectively obtaining 5-10 PNMR curves for the sample particle solution, calculating the concentration of the P element in the sample particle solution by taking an average value according to the relative peak integral areas of the PNMR curve of the internal standard solution and the PNMR curves of the 5-10 solutions to be detected, converting to obtain the mass ratio of the P element in the organic ligand to the sample particles, and calculating to obtain the content of the quantum dot surface ligand. More preferably, the content ratio of the P element is obtained by taking an average value after the maximum value and the minimum value are cut off according to the relative peak integral areas of the PNMR curve of the internal standard substance solution and the PNMR curves of the 5-10 solutions to be detected respectively.
Preferably, in the internal standard substance solution, the internal standard substance is triphenyl phosphate, tributyl phosphate or monocrotophos, and the like, but is not limited thereto, the concentration of the internal standard substance solution is 10-60mg/mL, and the solvent of the internal standard substance solution is deuterated chloroform.
Preferably, in the sample particle solution, the concentration of the sample particle solution is 10-60mg/ml, and the solvent of the sample particle solution is deuterated chloroform.
Further, a method for configuring quantum dot ink is also provided, which comprises:
s301, providing sample particles, wherein each particle in the sample particles comprises a quantum dot and a phosphorus-containing organic ligand bound on the surface of the quantum dot, the quantum dot does not contain phosphorus element, the organic ligands are one or more, and when the organic ligands are multiple, the molar molecular mass of each organic ligand is different from that of each other by no more than 5%;
s302, respectively measuring the surface ligand content of the sample particles of different batches according to the measuring method of the surface ligand content of the quantum dots;
s303, selecting one batch of sample particles as a reference batch of sample particles;
s304, when the content of the surface ligand of the quantum dots of the other batch of samples is not more than 10% different from the content of the surface ligand of the reference batch of particles, using the other batch of sample particles for configuring ink;
s305, when the content of the surface ligand of the other batch of the sample quantum dots is different from the content of the surface ligand of the reference batch of particles by more than 10%, adjusting the content of the surface ligand of the other batch of the quantum dots to be within 10% of the content of the surface ligand of the reference batch of particles, and then using the other batch of particles with the adjusted content of the surface ligand for configuring ink.
In the step S304, in order to ensure the stability of the quantum dot ink, the invention provides a method for preparing the quantum dot ink. Specifically, aiming at a plurality of different batches of same-kind sample particles, a nuclear magnetic resonance method is utilized to select a reference batch of sample particles and determine the content of the organic ligand on the surface of the quantum dot of the reference batch of sample particles and record the content as omega1Determining the organic ligand content omega on the surface of other quantum dots prepared in other batches (for example, the organic ligand content omega on the surface of other quantum dots obtained based on the same method or the same preparation process2According to ω1And omega2The relationship between the other batches of sample particles determines whether the other batches of sample particles can be mixed directly with the other batches of sample particles for use in the ink configuration. If omega2=【90%ω1, 110%ω1】（ω2Value of (d) is at 90% omega1~110%ω1And (b) the organic ligand content on the surface of the quantum dot of the other batch of sample particles is consistent with the organic ligand content on the surface of the quantum dot of the reference sample particle, and the quantum dot ink can be prepared. In the process, using the other batch of sample particles to formulate ink comprises: using the other batch of sample particles directly for preparing ink; or mixing the other batch of sample particles with other sample particles satisfying the condition (the reference particle and/or surface ligand content is 90% omega)1~110%ω1Sample particles in between) are mixed for configuring the ink.
In the step S305, if ω is2<90%ω1Regulation of omega by ligand re-exchange2To 90%ω1~110%ω1Then preparing quantum dot ink; if omega2>110%ω1The omega is regulated by a ligand-removing method2To 90% omega1~110%ω1And preparing the quantum dot ink. The method for preparing the quantum dot ink can ensure the uniformity of the quality of the quantum dot ink, ensure the solubility, the drying rate and the coffee ring effect of quantum dot ink in different batches to be the same, and improve the uniformity of the pixel resolution, the turn-on voltage and the photoelectric efficiency of the quantum dot display panel. The step of using the other batch of sample particles with the adjusted surface ligand content for preparing the ink comprises the following steps: using the other batch of sample particles directly for preparing ink; or mixing the other batch of sample particles with other sample particles satisfying the condition (the reference particle and/or surface ligand content is 90% omega)1~110%ω1Sample particles in between) are mixed for configuring the ink.
Specifically, the surface ligand content of the reference batch of particles is noted as ω1And the content omega of the ligand on the surface of the quantum dots of other batches of samples2Less than 90% omega1When in use, the content of the surface ligand of the quantum dots of other batches of samples can be increased by a quantum dot ligand re-exchange method, which comprises the steps of dissolving other batches of sample particles in a non-polar solvent, and then adding the original surface ligand to carry out exchange at 25-100 ℃. The nonpolar solvent can be selected from one or more of chloroform, n-hexane, heptane, octane, toluene, chlorobenzene, dichlorobenzene, carbon tetrachloride, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, cyclodecane and cycloundecane. The ligand is added in the exchange process in an amount of (90% omega) of substance1-ω2)n~(110%ω1-ω2) And n, wherein n is the mass amount of the ligand added in the preparation process of the quantum dot.
Specifically, the surface ligand content of the reference batch of particles is noted as ω1And the content omega of the ligand on the surface of the quantum dots of other batches of samples2Higher than 110% omega1Then, the quantum dots of other batches of samples can be reduced by a method of removing ligandsSurface ligand content. For example, the ligand removal method may be an acid treatment method, in which the other batch of sample particles is mixed with a mineral acid solution to remove the ligands on the surfaces of the other batch of sample particles. At this time, the inorganic acid solution ionizes to give H+And anions, surface ligands and H+The binding generates a weak acid, thereby removing the ligand. The inorganic acid is preferably selected from hydrochloric acid, nitric acid or sulfuric acid, and the inorganic acid solution is an aqueous solution, a methanol solution or an ethanol solution with the volume concentration of the acid being 1.25% -5%. The amount of the material of the de-ligand agent added in the de-ligand process is mQ(ω2-110%ω1)/Ml~mQ(ω2-90%ω1)/MlWherein m isQThe mass of the other batch of sample particles, MlIs the molar molecular mass of the characteristic element (in the present invention, the P element).
The present invention will be described in detail below with reference to examples.
Example 1
(1) The quantum dot sample is CdZnSe/CdZnSe/ZnSe quantum dots, and the surface ligand is tetradecyl phosphoric acid. The method comprises the following steps of determining the content of the P-containing surface ligand in a standard quantum dot sample, wherein the steps comprise: 10mg of triphenyl phosphate was weighed out and added to 1.000 mL of deuterated chloroform to prepare a 10.0 mg/mL internal standard solution. Weighing quantum dot samples, adding 0.500 mL of deuterated chloroform to prepare a solution of 60.0 mg/mL, and then adding 0.1 mL of internal standard substance solution to obtain a sample solution. Respectively placing the internal standard substance solution and the sample solution in a nuclear magnetic resonance device, adjusting the working frequency of the nuclear magnetic resonance device to be 150MHz and the testing temperature to be 275K,31the spectral width of PNMR was 70 Hz. Obtaining an internal standard substance solution PNMR curve map and 5 sample solution PNMR curve maps; and (3) performing integral operation, after the maximum value and the minimum value are cut off, averaging to obtain an integral result, and obtaining that the content ratio of the P element in the quantum dot sample is 5.43%.
(2) Determining the content omega of the P element in other batches of CdZnSe/CdZnSe/ZnSe quantum dot surface ligands in the same preparation process2. Obtaining another batch of CdZnSe/CdZnSe/ZnSe quantum dot surface preparation according to the reaction and test processP element content omega in body25.40%, omega2At 90% omega1~110%ω1In the range, the method can be directly used for preparing quantum dot ink.
Example 2
(1) The quantum dot sample is CdZnS/ZnS quantum dot, and the surface ligand is hexadecyl phosphoric acid. The method comprises the following steps of determining the content of the P-containing surface ligand in a standard quantum dot sample, wherein the steps comprise: 30mg of tributyl phosphate is weighed and added with 1.000 mL of deuterated chloroform to prepare 30.0 mg/mL of internal standard substance solution. Weighing quantum dot samples, adding 0.500 mL of deuterated chloroform to prepare a 45 mg/mL solution, and then adding 0.200 mL of internal standard substance solution to obtain a sample solution. Respectively placing the internal standard substance solution and the sample solution in nuclear magnetic resonance equipment, adjusting the working frequency of the nuclear magnetic resonance equipment to 180 MHz and the testing temperature to 320K,31the spectral width of PNMR was 90 Hz. During testing, the internal standard substance is used for base line scanning, and then the sample is tested. Obtaining an internal standard substance solution PNMR curve map and 8 sample solution PNMR curve maps; and performing integral operation, after the maximum value and the minimum value are cut off, averaging to obtain an integral result, and obtaining that the content ratio of the P element in the quantum dot sample is 6.38%.
(2) Determining P-containing surface ligand content omega of other batches of CdZnSe/ZnS quantum dots prepared in the same preparation process2. Obtaining the content omega of the P element in the other batch of CdZnSe/ZnS quantum dot surface ligand according to the testing process in the step (1)27.8%, omega2Greater than 110% omega1Firstly, the quantum dots are treated by a ligand removing agent, and the P element in the surface ligand is adjusted to 90 percent omega1~110%ω1After the range, the ink is disposed.
(3) The method for removing the ligand from the quantum dot comprises the following steps: taking 300mg of the CdZnSe/ZnS quantum dot in the step (2), and adding the CdZnSe/ZnS quantum dot into the quantum dot containing 0.15mmol of H+Stirring the mixture in an ethanol solution with the volume concentration of hydrochloric acid of 2% at room temperature, and washing the mixture by using a mixed solution of chloroform and ethanol after stirring to obtain the quantum dots with part of ligands removed.
(4) Determining the content omega of the P element in the CdZnSe quantum dot surface ligand after ligand removal3. Measurement according to step (1)In the testing process, the content omega of the P element in the ligand on the surface of the CdZnSe quantum dot after the ligand is removed is obtained36.45%, omega3At 90% omega1~110%ω1Within the range, the ink can be directly disposed.
Example 3
(1) The quantum dot sample is CdZnSe quantum dot, and the surface ligand is octadecyl phosphoric acid. The method comprises the following steps of determining the content of the P-containing surface ligand in a standard quantum dot sample, wherein the steps comprise: 30mg of monocrotophos was weighed out and added to 1.000 mL of deuterated chloroform to prepare a 30.0 mg/mL internal standard solution. Weighing quantum dot samples, adding 0.500 mL of deuterated chloroform to prepare a solution of 30 mg/mL, and then adding 0.05 mL of internal standard substance solution to obtain a sample solution. Respectively placing the internal standard substance solution and the sample solution in nuclear magnetic resonance equipment, adjusting the working frequency of the nuclear magnetic resonance equipment to 200MHz and the testing temperature to 300K,31the spectral width of PNMR was 100 Hz. Obtaining an internal standard substance solution PNMR curve map and 10 sample solution PNMR curve maps; and performing integral operation, after the maximum value and the minimum value are cut off, averaging to obtain an integral result, and obtaining that the content ratio of the P element in the quantum dot sample is 7.52%.
(2) Determining the content omega of the P element in the surface ligands of other batches of the quantum dots CdZnSe quantum dots in the same preparation process2. Obtaining the content omega of the P element in the surface ligand of another batch of CdZnSe quantum dots according to the reaction and the test process25.6%, omega2Less than 90% omega1Firstly, ligand exchange is carried out on the quantum dots, and the P element in the surface ligand is adjusted to 90 percent omega1~110%ω1After the range, the ink formulation is performed.
(3) And (4) re-exchanging the quantum dot ligands. And (3) taking the CdZnSe quantum dots obtained in the step (2), wherein the content of octadecyl phosphoric acid and trioctyl phosphine oxide ligand added in the preparation of the quantum dots is known to be 14 mmol. Adding the CdZnSe quantum dots into chloroform to prepare a solution of 10mg/ml, adding 0.8mmol of octadecyl phosphoric acid into the solution, stirring the mixture at 40 ℃, and washing the mixture by using a mixed solution of chloroform and ethanol after stirring to obtain the quantum dots after ligand re-exchange.
(4) Determining P in CdZnSe quantum dot surface ligand after ligand re-exchangeContent of element omega3. According to the testing process of the step 1), the content omega of the P element in the CdZnSe quantum dot surface ligand after ligand exchange is obtained37.36%, omega3At 90% omega1~110%ω1Within the range, the ink can be directly prepared.
While the method for configuring quantum dot ink according to the embodiments of the present invention has been described in detail, it will be apparent to those skilled in the art that the embodiments of the present invention can be modified in various ways, such as the following descriptions.
Claims (14)
1. A method for measuring the content of a ligand on the surface of a quantum dot is characterized by comprising the following steps:
providing sample particles, wherein each particle in the sample particles comprises a quantum dot and a phosphorus-containing organic ligand bound on the surface of the quantum dot, the quantum dot does not contain phosphorus element, the organic ligands are one or more, and when the organic ligands are multiple, the molar molecular mass of each organic ligand is different from that of each other by no more than 5%;
and (3) measuring the mass percentage of the P element in the organic ligand in the sample particles by using a nuclear magnetic resonance analyzer, and calculating the mass percentage as the content of the ligand on the surface of the quantum dot.
2. The method for determining the content of the ligand on the surface of the particle according to claim 1, wherein the step of determining the content of the P element in the organic ligand in the mass percent of the sample particle as the content of the ligand on the surface of the quantum dot by using a nuclear magnetic resonance analyzer comprises the following steps:
providing an internal standard solution, wherein the solvent of the internal standard solution is deuterated chloroform, and obtaining a PNMR curve of the internal standard solution by using nuclear magnetic resonance equipment;
providing a sample particle solution, wherein a solvent of the sample particle solution is deuterated chloroform, adding the internal standard solution into the sample particle solution to prepare a solution to be detected, and obtaining a PNMR curve of the solution to be detected by using nuclear magnetic resonance equipment;
and performing integral operation according to the PNMR curve of the internal standard substance solution and the PNMR curve of the solution to be detected, calculating to obtain the concentration of the P element in the sample particle solution, and converting to obtain the mass percentage content of the P element in the organic ligand in the sample particles, wherein the mass percentage content is counted as the content of the quantum dot surface ligand.
3. The method for measuring the content of the ligand on the surface of the quantum dot according to claim 2, wherein the concentration of the internal standard substance in the internal standard solution is 10-60 mg/mL.
4. The method for measuring the content of the ligand on the surface of the quantum dot according to claim 2, wherein the internal standard substance in the internal standard solution is selected from phenyl ester, tributyl phosphate or monocrotophos.
5. The method for determining the content of the ligand on the surface of the quantum dot according to claim 2, wherein the concentration of the sample particles in the sample solution is 10-60 mg/ml.
6. The method for determining the content of the ligand on the surface of the quantum dot according to claim 2, wherein the determination conditions for obtaining the PNMR curve of the internal standard solution by using the nuclear magnetic resonance device or obtaining the PNMR curve of the solution to be measured by using the nuclear magnetic resonance device are as follows: the working frequency is 150-200MHz, the testing temperature is 275-325K, and the spectrum width of PNMR is 64-102 Hz.
7. The method for determining the content of the ligand on the surface of the quantum dot according to claim 6, wherein a nuclear magnetic resonance device is used for obtaining 5-10 PNMR curves of the solution to be measured, integral operation is respectively carried out on the PNMR curves of the internal standard solution and the 5-10 PNMR curves of the solution to be measured, the average value is taken for calculation to obtain the concentration of the P element in the sample particle solution, the mass ratio of the P element in the organic ligand to the sample particle is obtained through conversion, and the content of the ligand on the surface of the quantum dot is obtained through calculation.
8. The method for measuring the content of the ligand on the surface of the quantum dot according to claim 1, wherein the quantum dot is a univalent quantum dot, a binary quantum dot, a ternary quantum dot or a quaternary quantum dot.
9. The method for measuring the content of the ligand on the surface of the quantum dot according to claim 8, wherein the univalent quantum dot is selected from Au, Ag, Cu, Pt or C quantum dots;
the binary quantum dots are selected from CdSe, ZnSe, PbSe, CdTe, ZnO, MgO and CeO2、NiO、TiO2InP or CaF2Quantum dots;
the ternary quantum dots are selected from CdZnSe and NaYF4、NaCdF4ZnCdTe, CdZnSe/ZnSe, CdSe/CdZnSe/CdZnSe/ZnSe or CdZnSe/CdZnSe/ZnSe quantum dots;
the quaternary quantum dots are selected from CdSZnSeyS, CdSe/ZnS, CdSe/CdS/ZnS, CdSe/ZnSe/ZnS, CdSZnSe/CdSZnS/ZnS or InP/ZnS quantum dots.
10. A method for configuring quantum dot ink, comprising:
providing sample particles, wherein each particle in the sample particles comprises a quantum dot and organic ligands containing phosphorus, wherein the organic ligands are bound on the surface of the quantum dot, the quantum dot does not contain phosphorus, the organic ligands are the same or different, and when the organic ligands are different, the molar molecular mass of each organic ligand is different by no more than 5%;
measuring the surface ligand content of different batches of said sample particles according to the method for measuring the surface ligand content of particles according to any one of claims 1 to 9;
selecting one batch of sample particles as a reference batch of sample particles;
when the surface ligand content of other batch of sample particles is different from the surface ligand content of the reference batch of particles by no more than 10%, using the other batch of sample particles for configuring ink;
when the surface ligand content of other batch of sample particles is different from the surface ligand content of the reference batch of particles by more than 10%, adjusting the surface ligand content of the other batch of particles to be within 10% of the surface ligand content of the reference batch of particles, and then using the other batch of particles after adjusting the surface ligand content for configuring ink.
11. The method of claim 10, wherein the surface ligand content of the reference batch of particles is denoted as ω1When the ligand content omega on the surface of other batches of sample particles2Higher than 110% omega1Reducing the ligand content on the surface of the other batch of sample particles by a de-ligand method, wherein the de-ligand method comprises the following steps: and mixing the other batch of sample particles with a mineral acid solution, and removing the ligands on the surfaces of the other batch of sample particles.
12. The method according to claim 11, wherein the inorganic acid solution is selected from a hydrochloric acid solution, a nitric acid solution, or a sulfuric acid solution;
and/or the volume concentration of the inorganic acid solution is 1.25-5%;
and/or the solvent in the inorganic acid solution is water, methanol or ethanol.
13. The method of claim 11, wherein the amount of the inorganic acid is mQ(ω2-110%ω1)/Ml~mQ(ω2-90%ω1)/MlMixing the other batch of sample particles with a mineral acid solution, wherein mQIs the mass of the other batch of sample particles, MlIs the molar mass of P.
14. The method of claim 11, wherein different batches of the sample particles are prepared by the same preparation process.
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