CN112824477B - Preparation method and application of core-shell quantum dot - Google Patents

Preparation method and application of core-shell quantum dot Download PDF

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CN112824477B
CN112824477B CN201911147617.5A CN201911147617A CN112824477B CN 112824477 B CN112824477 B CN 112824477B CN 201911147617 A CN201911147617 A CN 201911147617A CN 112824477 B CN112824477 B CN 112824477B
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胡保忠
毛雁宏
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Najing Technology Corp Ltd
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Abstract

The invention relates to a preparation method and application of a core-shell quantum dot, comprising the following steps: (1) Providing a solution containing quantum dots, wherein the solution containing quantum dots is a raw material for preparing core-shell quantum dots; (2) Mixing raw materials for preparing the core-shell quantum dot with short-chain fatty acid zinc with a carbon chain length of less than or equal to 8 and long-chain fatty acid with a carbon chain length of more than or equal to 12, and reacting at a first temperature to obtain an intermediate solution; (3) Mixing the intermediate solution with a precursor containing Se element, and reacting at a second temperature to coat a ZnSe shell layer on the surface of the quantum dot to obtain a solution containing a core-shell quantum dot intermediate; (4) And (3) taking the solution containing the core-shell quantum dot intermediate as the raw material for preparing the core-shell quantum dot in the step (1), and coating the core-shell quantum dot by repeating the steps (2) and (3) at least once to obtain the core-shell quantum dot. The quantum yield of the core-shell quantum dot is kept above 95% along with the increase of the thickness of the ZnSe shell, so that the external quantum efficiency and the service life of a photoelectric device applying the core-shell quantum dot can be improved.

Description

Preparation method and application of core-shell quantum dot
Technical Field
The invention relates to the technical field of quantum dots, in particular to a preparation method and application of a core-shell quantum dot.
Background
At present, the outer layers of blue light quantum dots such as CdZnS/ZnS, cdZnSeS/ZnS, znCdSe/ZnS and the like are coated with thicker ZnS shells, so that the HOMO of the blue light quantum dots is deeper, effective injection of holes is not facilitated, the service life of the photoelectric device is lower, and the commercialized minimum requirements cannot be met.
In quantum dot synthesis, znSe is typically used as a shell to encapsulate CdSe, cdZnSe, inP equivalent quantum dots due to its more appropriate conduction and valence band positions and more matched unit cell parameters. Researches show that the ZnSe shell layer with the thickness of about 7nm is coated outside the ZnCdSe, so that the HOMO of the blue light quantum dot can be effectively improved, the energy level difference between the blue light quantum dot and the TFB material of the hole transport layer is shortened, and the photoelectric device is 100cd/m 2 And the lighting condition of (2) reached a level of 7000 h. However, when the ZnSe shell is prepared by the existing heating method, one-pot method or dripping coating method, znO and ZnSeO are formed when the thickness of the ZnSe shell is larger, such as more than 3nm 3 Iso-oxidation products, resulting in lattice dislocation of ZnSe shell during growthThereby creating defect sites. The defect sites can capture excitons and generate non-radiative transitions, which directly lead to the rapid reduction of quantum yield of blue light quantum dots, and the quantum yield is only about 73 percent and is far lower than the level of green light quantum dots and red light quantum dots which are close to 100 percent, so that the external quantum efficiency of a photoelectric device using the blue light quantum dots is only about 8 percent and is far lower than the external quantum efficiency of 20 percent of the photoelectric device using the green light quantum dots and the red light quantum dots.
Disclosure of Invention
Based on the above, it is necessary to provide a method for preparing core-shell quantum dots and applications thereof; the quantum yield of the core-shell quantum dot obtained by the preparation method is always kept above 95% along with the improvement of the thickness of the ZnSe shell, so that the external quantum efficiency and the service life of a photoelectric device applying the core-shell quantum dot can be improved.
In a first aspect of the present invention, a method for preparing a core-shell quantum dot is provided, comprising the steps of:
(1) Providing a solution containing quantum dots, wherein the solution containing quantum dots is a raw material for preparing core-shell quantum dots;
(2) Mixing the raw materials for preparing the core-shell quantum dot with short-chain fatty acid zinc with the carbon chain length less than or equal to 8 and long-chain fatty acid with the carbon chain length more than or equal to 12, and reacting at a first temperature to obtain an intermediate solution;
(3) Mixing the intermediate solution with a precursor containing Se elements, and reacting at a second temperature to coat a ZnSe shell layer on the surface of the quantum dot to obtain a solution containing a core-shell quantum dot intermediate;
(4) And (3) taking the solution containing the core-shell quantum dot intermediate as a raw material for preparing the core-shell quantum dot in the step (1), and coating the core-shell quantum dot by repeating the steps (2) and (3) at least once to obtain the core-shell quantum dot.
Further, the thickness of the ZnSe shell obtained by the single coating in the step (3) is 1.5nm or less, preferably 0.5nm to 1.5nm.
Further, the total thickness of ZnSe shell layers of the core-shell quantum dots is 1 nm-10 nm.
Further, the total thickness of the ZnSe shell is 3nm to 10nm.
Further, the molar ratio of the long-chain fatty acid to the short-chain fatty acid zinc is 2:1 or more, preferably 2:1 to 4:1.
Further, the first temperature is 100 ℃ to 240 ℃, and the second temperature is 280 ℃ to 310 ℃.
Further, the molar ratio of Se element to Zn element is 1:2-2:1, and the molar concentration of Se element in the precursor containing Se element is 0.5 mmol/mL-4 mmol/mL.
Further, the solution containing the quantum dots is a product system containing the quantum dots synthesized by a solution method.
Further, the quantum dots include at least one of CdZnSeS, cdSe, cdZnSe, znSe, cdSeS, inP, inZnP.
In a second aspect, the invention provides a quantum dot composition, which comprises the core-shell quantum dot prepared by the preparation method.
In a third aspect of the invention, an optoelectronic device is provided, including the core-shell quantum dot prepared by the preparation method described above.
In the preparation method of the invention, the first ZnSe shell layer and the ZnSe shell layer are obtained by coating at least twice, and the thickness of each coating is not more than 1.5nm, thereby avoiding excessive accumulation of long-chain fatty acid zinc and reducing the decomposition of the long-chain fatty acid zinc to generate ZnO or ZnSeO under the high-temperature reaction condition 3 The probability of the oxidized products is equal, so that the internal defects of the core-shell quantum dots are reduced to the maximum extent, the ZnSe shell of the core-shell quantum dots grows slowly and maintains higher quantum yield; secondly, because the ZnSe shell is obtained by multiple coating, short-chain fatty acid zinc and long-chain fatty acid are in-situ added in each coating, the short-chain fatty acid zinc which is added in each coating is not excessive, and small molecular acids such as formic acid, acetic acid, propionic acid and butyric acid are formed in the short-chain fatty acid radicals when the short-chain fatty acid radicals in the short-chain fatty acid zinc are replaced in each adding long-chain fatty acid, and can decompose and etch oxidation products on the surfaces of the core-shell quantum dots, so that the internal defects of the core-shell quantum dots are further decomposed and eliminated, and the quantum yield of the core-shell quantum dots is improved; third stepAfter the primary shell layer is coated, the purification of the core-shell quantum dot raw material and the core-shell quantum dot intermediate is not needed, so that Se on the surfaces of the core-shell quantum dot raw material and the core-shell quantum dot intermediate is not easy to oxidize, and the internal quality of the core-shell quantum dot is ensured. Therefore, the quantum yield of the core-shell quantum dot obtained by the preparation method disclosed by the invention is always kept above 95% along with the improvement of the thickness of the ZnSe shell, so that the external quantum efficiency and the service life of a photoelectric device applying the core-shell quantum dot can be improved.
Drawings
FIG. 1 is an electron microscope image of core-shell quantum dots obtained in example 2;
FIG. 2 is an electron microscope image of the core-shell quantum dots obtained in example 4;
fig. 3 is an electron microscope image of the core-shell quantum dot obtained in example 7.
Detailed Description
The preparation method and application of the core-shell quantum dot provided by the invention are further described below.
The preparation method is mainly used for preparing the blue light quantum dot with the core-shell structure, so that the quantum yield of the blue light quantum dot is always kept above 95% along with the improvement of the thickness of the ZnSe shell, and the external quantum efficiency and the service life of a photoelectric device applying the blue light quantum dot are further improved, so that the blue light quantum dot is more similar to the requirements of commercial application.
In the preparation method of blue light quantum dots with ZnSe as a shell layer, the applicant has found that ZnO and ZnSeO are prepared by long and intensive research 3 The iso-oxidation products are mainly formed in two stages: firstly, after the quantum dots serving as raw materials are purified, the bare quantum dots can be slowly oxidized by air to generate an oxidation product; secondly, the reaction system is usually reacted at a high temperature of about 300 ℃, the reaction time is too long, and excessive fatty acid zinc precursor can be decomposed to generate oxidation products.
In order to avoid the generation of oxidation products in the two stages, the preparation method of the core-shell quantum dot provided by the invention comprises the following steps:
(1) Providing a solution containing quantum dots, wherein the solution containing quantum dots is a raw material for preparing core-shell quantum dots;
(2) Mixing the raw materials for preparing the core-shell quantum dots with short-chain fatty acid zinc with the carbon chain length less than or equal to 8 and long-chain fatty acid with the carbon chain length more than or equal to 12, and reacting at a first temperature to obtain an intermediate solution;
(3) Mixing the intermediate solution with a precursor containing Se elements, and reacting at a second temperature to coat a ZnSe shell layer on the surface of the quantum dot to obtain a solution containing a core-shell quantum dot intermediate;
(4) And (3) taking the solution containing the core-shell quantum dot intermediate as a raw material for preparing the core-shell quantum dot in the step (1), and coating the core-shell quantum dot by repeating the steps (2) and (3) at least once to obtain the core-shell quantum dot.
In the step (1), the solution containing the quantum dots is a product system containing the quantum dots synthesized by a solution method, and the specific solution method is not limited and mainly comprises at least one of a CdZnSeS product system, a CdZnSe product system, a ZnSe product system and a CdSeS product system. The product system containing the quantum dots synthesized by the solution method is directly used as the raw material for preparing the core-shell quantum dots, so that not only can the purification of the quantum dots serving as the core raw material be avoided, the operation is simplified, the production efficiency is improved, but also the slow oxidation of the exposed quantum dot core raw material by air can be avoided, and the internal defects of the core-shell quantum dots are reduced.
In the step (2), the zinc short-chain fatty acid and the long-chain fatty acid are mixed, and in the process of reacting at the first temperature, the long-chain fatty acid reacts with the zinc short-chain fatty acid, specifically, the long-chain fatty acid replaces the short-chain fatty acid radical in the zinc short-chain fatty acid to form the zinc long-chain fatty acid. The long-chain fatty acid zinc is used as a precursor of Zn element in a ZnSe shell layer to exist in an intermediate solution, and replaced short-chain fatty acid radicals can form short-chain fatty acids such as formic acid, acetic acid, propionic acid, butyric acid and the like, so that the long-chain fatty acid zinc is used for decomposing oxidation products on the surface of the quantum dot.
In some embodiments, the short chain fatty acid zinc comprises at least one of zinc formate, zinc acetate, zinc propionate, zinc butyrate, and the like, preferably at least one of zinc formate, zinc acetate, zinc propionate. The long chain fatty acid comprises at least one of oleic acid, stearic acid, isostearic acid and the like.
Considering that zinc ions are divalent ions, each short-chain fatty acid zinc contains two short-chain fatty acid radicals, so that in order to fully replace short-chain fatty acid zinc with long-chain fatty acid zinc, the molar ratio of the long-chain fatty acid to the short-chain fatty acid zinc is greater than or equal to 2:1, preferably 2:1-4:1.
In addition, in order for the long chain fatty acid to be able to adequately replace the short chain fatty acid zinc with the long chain fatty acid zinc, the first temperature needs to be greater than the boiling point of the short chain fatty acid, so in some embodiments, the first temperature is preferably 100 ℃ to 240 ℃, specifically adjusted according to the boiling point of the short chain fatty acid.
In the step (3), long-chain fatty acid zinc existing in the intermediate solution reacts with a precursor containing Se element at the second temperature to grow on the surface of the quantum dot to form a ZnSe shell layer.
It can be understood that when the growth of the ZnSe shell layer is repeatedly performed, in order to continue to grow the ZnSe shell layer on the surface of the core-shell quantum dot intermediate, the quantum dot at this time refers to the core-shell quantum dot intermediate.
In order to ensure the internal quality of the core-shell quantum dot, the retention of oxidation products in the core-shell quantum dot is reduced or avoided, and the thickness of a single-grown ZnSe shell layer is 1.5nm or less, and is more preferably 0.5nm to 1.5nm in view of processing efficiency.
In some embodiments, the precursor comprising a Se element comprises at least one of Se-TOP (selenium-trioctylphosphine), se-TBP (selenium-tributylphosphine), se-DPP (selenium-diphenylphosphine).
In order to enable Se element in the precursor and Zn element in long-chain fatty acid zinc to fully react to form a ZnSe shell layer with the thickness of less than or equal to 1.5nm, the molar concentration of Se element in the precursor containing Se element is 0.5 mmol/mL-4 mmol/mL, and the molar ratio of Se element to Zn element is preferably 1:2-2:1. In order to further avoid the generation of oxidation products by the decomposition of zinc long-chain fatty acid in excess and improve the internal quality of the core-shell quantum dot, the molar ratio of Se element to Zn element is more preferably 1:1.
It is understood that the long-chain fatty acid can completely replace the short-chain fatty acid zinc with the long-chain fatty acid zinc, and therefore, the addition amount of Zn element can be controlled by the addition amount of the short-chain fatty acid zinc according to the molar ratio range. In the solution of the quantum dots serving as the raw material for preparing the core-shell quantum dots, the molar quantity of the quantum dots is calculated according to the factors such as the shape, the size and the like of the quantum dots and the conditions such as the specific thickness of the ZnSe shell needing to be coated.
In order to allow the long chain fatty acid zinc and the precursor containing the Se element to sufficiently react to form the ZnSe shell, in some embodiments, the second temperature is 280 ℃ to 310 ℃ and the heating time is 20 minutes to 60 minutes, which is specifically adjusted according to the activity of the precursor containing the Se element.
In the step (4), the obtained solution containing the core-shell quantum dot intermediate is directly used as the raw material for preparing the core-shell quantum dot in the step (1), the steps (2) and (3) are repeatedly carried out to further grow the ZnSe shell layer and improve the total thickness of the ZnSe shell layer, so that the solution containing the core-shell quantum dot intermediate does not need to be purified, the surface of the exposed core-shell quantum dot intermediate is prevented from being slowly oxidized by air, and the complex purification step is avoided, and the operation is simple.
Meanwhile, the ZnSe shell layer is obtained in a repeated coating mode by repeating the step (2) and the step (3), so that the consumption of short-chain fatty acid zinc in single coating can be reduced, and the short-chain fatty acid zinc is ensured not to be excessive, thereby effectively avoiding excessive accumulation of long-chain fatty acid zinc, reducing the probability of generating an oxidation product by decomposing long-chain fatty acid zinc at high temperature, furthest reducing the internal defect of the core-shell quantum dot, enabling the ZnSe shell layer of the core-shell quantum dot to slowly grow and maintaining higher quantum yield. And each time short-chain fatty acid zinc and long-chain fatty acid are supplemented in situ, small molecular acids such as formic acid, acetic acid, propionic acid, butyric acid and the like are generated, so that ZnO or ZnSeO can be continuously decomposed and etched 3 And (3) waiting for oxidation products, so that internal defects of the core-shell quantum dots are further decomposed and eliminated, and the quantum yield of the core-shell quantum dots is improved.
It can be understood that the step (2) and the step (3) can be repeated once or repeated multiple times to obtain the core-shell quantum dot with the total thickness of the ZnSe shell of 1 nm-10 nm. Considering the effect of the core-shell quantum dot when applied to an optoelectronic device, the total thickness of the ZnSe shell is preferably 3nm to 10nm.
In some embodiments, when the total thickness X of ZnSe shells of the core-shell quantum dots is 1.5nm or less, the thickness Y of ZnSe shells coated each time in step (3) is less than X, thereby obtaining core-shell quantum dots by coating at least twice. When the total thickness X of ZnSe shell layers of the core-shell quantum dot is more than 1.5nm, the thickness Y of ZnSe shell layers coated in the step (3) is less than or equal to 1.5nm, preferably 0.5 nm-1.5 nm, so that the core-shell quantum dot is obtained through at least two coating steps.
It is understood that the thickness Y of the ZnSe shell layer obtained by coating may be the same or different at each coating.
For example, the core-shell quantum dot is obtained by cladding twice, the total thickness of the shell layers of the core-shell quantum dot is X, and when the thickness of the ZnSe shell layer obtained by cladding for the first time and the thickness of the ZnSe shell layer obtained by cladding for the second time are both Y 1 When then x=2y 1 The method comprises the steps of carrying out a first treatment on the surface of the When the thickness of the ZnSe shell obtained by the first coating is Y 1 The thickness of the ZnSe shell obtained by the second cladding is Y 2 When then X=Y 1 +Y 2 。
Also, the core-shell quantum dot is obtained by five cladding, the total thickness of the shell layers of the core-shell quantum dot is X, and when the thickness of the ZnSe shell layer obtained by each cladding is Y 1 When then x=5y 1 The method comprises the steps of carrying out a first treatment on the surface of the When the thickness of ZnSe shell obtained by the first coating and the second coating is Y 1 The thickness of ZnSe shell obtained by the third coating and the fourth coating is Y 2 The thickness of ZnSe shell obtained by the fifth coating is Y 3 When then x=2y 1 +2Y 2 +Y 3 The method comprises the steps of carrying out a first treatment on the surface of the When the thickness of ZnSe shell obtained by each coating is different, Y is respectively 1 、Y 2 、Y 3 、Y 4 、Y 5 When then X=Y 1 +Y 2 +Y 3 +Y 4 +Y 5 。
Thus, in the preparation method of the present invention, the preparation is carried out by multiple coatingThe ZnSe shell layer can control the thickness of the ZnSe shell layer obtained by single coating and the recycling of the solution, and ZnO or ZnSeO in two stages can be effectively avoided without purification 3 And the generation of equal oxidation products and the effective elimination of the generated oxidation products can be realized, so that the internal quality of the core-shell quantum dot can be effectively improved, and the quantum yield of the obtained core-shell quantum dot is always kept above 95 percent along with the improvement of the thickness of the ZnSe shell.
It will be appreciated that in the preparation of other core-shell quantum dots (other than blue quantum dots), such as CdSe product systems, inP product systems, inZnP product systems, if ZnSe is used as the shell layer, the method of at least two cladding of the present invention may be used.
The invention also provides a quantum dot composition, which comprises the core-shell quantum dot prepared by the preparation method. The quantum dot composition also comprises quantum dot ink, quantum dot glue and the like.
The invention also provides a photoelectric device which adopts the core-shell quantum dot. The optoelectronic device may be a quantum dot light conversion film, a quantum dot color film, devices used in combination with LEDs, quantum dot light emitting diodes, and the like.
The quantum yield of the core-shell quantum dot is always kept above 95% along with the increase of the thickness of the ZnSe shell, so that the external quantum efficiency and the service life of the quantum dot composition and the photoelectric device can be effectively improved.
Hereinafter, the preparation method and application of the core-shell quantum dot will be further described by the following specific examples.
Example 1:
0.2mmol of cadmium oleate, 2mmol of zinc oleate and 10g of ODE (octadecene) are weighed into a three-necked flask, the temperature is raised to 280 ℃ under the protection of nitrogen atmosphere, then 1mL of 0.5mmol/mL of Se-ODE (selenium-octadecene) is injected, and the temperature is raised to 300 ℃ for reaction for 10min. Then 0.33mL of 3mmol/mL Se-TBP (selenium-tributylphosphine) solution is added, the reaction is carried out for 20min at 300 ℃, and the temperature is reduced to the room temperature, thus obtaining the CdZnSe quantum dot solution with the concentration of 4.0 nm.
Under the protection of nitrogen, 1mmol of zinc acetate and 3mmol of oleic acid are added through a funnel without purifying the CdZnSe quantum dot solution, and then nitrogen is introduced for 30min after the temperature is raised to 150 ℃. And then adding 0.33mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 30min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer is 0.5nm.
Under the protection of nitrogen, 1mmol of zinc acetate and 2mmol of oleic acid are added through a funnel without purifying the CdZnSe/ZnSe quantum dot intermediate solution, and then nitrogen is introduced for 30min after the temperature is raised to 150 ℃. And then adding 0.66mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 30min to obtain the CdZnSe/ZnSe quantum dot, wherein the total thickness of a ZnSe shell layer is 1.0nm.
Example 2:
0.2mmol of cadmium oleate, 2mmol of zinc oleate and 10g of ODE (octadecene) are weighed into a three-necked flask, the temperature is raised to 280 ℃ under the protection of nitrogen atmosphere, then 1mL of 0.5mmol/mL of Se-ODE (selenium-octadecene) is injected, and the temperature is raised to 300 ℃ for reaction for 10min. Then 0.33mL of 3mmol/mL Se-TBP (selenium-tributylphosphine) solution is added, the reaction is carried out for 20min at 300 ℃, and the temperature is reduced to the room temperature, thus obtaining the CdZnSe quantum dot solution with the concentration of 4.0 nm.
Under the protection of nitrogen, 3mmol of zinc acetate and 7mmol of oleic acid are added through a funnel without purifying the CdZnSe quantum dot solution, and then nitrogen is introduced for 30min after the temperature is raised to 150 ℃. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 30min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer is 1.5nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 4mmol of zinc acetate and 8mmol of oleic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 150 ℃. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ for reaction for 40min to obtain the CdZnSe/ZnSe quantum dot shown in the figure 1, wherein the total thickness of a ZnSe shell layer is 3nm.
Example 3:
0.18mmol of cadmium oleate, 2mmol of zinc oleate and 10g of ODE are weighed into a three-necked flask, the temperature is raised to 280 ℃ under the protection of nitrogen atmosphere, 1.2mL of 0.5mmol/mL of Se-ODE is injected, and the temperature is raised to 300 ℃ for reaction for 20min. Then 0.4mL of 2mmol/mL Se-TBP solution is added, the reaction is carried out for 30min at 300 ℃, and the temperature is reduced to the room temperature, thus obtaining the CdZnSe quantum dot solution with the wavelength of 3.6 nm.
Under the protection of nitrogen, 4mmol of zinc propionate and 10mmol of tetradecanoic acid are added through a funnel, and then the temperature is raised to 180 ℃ and nitrogen is introduced for 20min. And then adding 1.0mL of 3mmol/mL Se-TOP solution into the solution, and heating to 290 ℃ to react for 60min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer is 1.4nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 3mmol of zinc formate and 10mmol of isostearic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 100 ℃. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 310 ℃ to react for 20min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 2.6nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 4mmol of zinc octoate and 10mmol of hexadecanoic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 240 ℃. And then adding 2mL of 2mmol/mL Se-TBP solution into the solution, heating to 300 ℃, and reacting for 30min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 4nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 3mmol of zinc caproate and 10mmol of stearic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 200 ℃. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, heating to 310 ℃, and reacting for 30min to obtain the CdZnSe/ZnSe quantum dot, wherein the total thickness of a ZnSe shell layer is 5nm.
Example 4:
0.2mmol of cadmium oleate, 2mmol of zinc oleate and 10g of ODE are weighed into a three-necked flask, the temperature is raised to 290 ℃ under the protection of nitrogen atmosphere, then 0.5mmol of Se-ODE is injected, and the temperature is raised to 300 ℃ for reaction for 5min. Then 1mL of 0.5mmol/mL Se-TBP solution is added, the reaction is carried out for 20min at 300 ℃, and the temperature is reduced to the room temperature, thus obtaining the CdZnSe quantum dot solution with the concentration of 3.0 nm.
Under the protection of nitrogen, 4mmol of zinc acetate and 10mmol of oleic acid are added through a funnel without purifying the CdZnSe quantum dot solution, and then nitrogen is introduced for 20min after the temperature is raised to 150 ℃. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 20min to obtain the CdZnSe/ZnSe quantum dot solution, wherein the thickness of a ZnSe shell layer is 1.5nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 3mmol of zinc acetate and 6mmol of oleic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 150 ℃. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 3nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 4mmol of zinc acetate and 10mmol of oleic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 180 ℃. And then adding 1.33mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 4.5nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 3mmol of zinc acetate and 6mmol of oleic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 180 ℃. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 60min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 5.8nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 3mmol of zinc acetate and 6mmol of oleic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 180 ℃. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 30min to obtain the CdZnSe/ZnSe quantum dot shown in the figure 2, wherein the total thickness of a ZnSe shell layer is 7nm.
Example 5:
0.2mmol of cadmium oleate, 2mmol of zinc oleate and 10g of ODE are weighed into a three-necked flask, the temperature is raised to 290 ℃ under the protection of nitrogen atmosphere, then 1.0mL of 0.5mmol/mL of Se-ODE is injected, and the temperature is raised to 300 ℃ for reaction for 5min. Then adding 1.0mL of 0.5mmol/mL Se-TBP, reacting for 20min at 300 ℃, and cooling to room temperature to obtain 3.0nm CdZnSe quantum dot solution.
Under the protection of nitrogen, 3mmol of zinc butyrate and 6mmol of hexadecanoic acid are added through a funnel, and then the temperature is raised to 200 ℃ and nitrogen is introduced for 20min. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 20min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer is 1.5nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 3mmol of zinc octoate and 8mmol of stearic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 240 ℃. And then 1.0mL of 3mmol/mL Se-TOP solution is added into the solution, the temperature is raised to 310 ℃ for reaction for 40min, and a CdZnSe/ZnSe quantum dot intermediate solution is obtained, wherein the thickness of a ZnSe shell layer reaches 3nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 4mmol of zinc propionate and 10mmol of oleic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 180 ℃. And then adding 1.33mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 4.5nm.
Under the protection of nitrogen, 5mmol of zinc caproate and 10mmol of oleic acid are added through a funnel without purifying the CdZnSe/ZnSe quantum dot intermediate solution, and then nitrogen is introduced for 30min after the temperature is raised to 200 ℃. And then adding 1.33mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 6nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 6mmol of zinc acetate and 12mmol of oleic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 180 ℃. And then adding 1.67mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 60min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 7.5nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 6mmol of zinc formate and 12mmol of oleic acid are added through a funnel under the protection of nitrogen, and then the temperature is raised to 120 ℃ and nitrogen is introduced for 30min. Then adding 2.0mL of 3mmol/mL Se-TBP solution into the solution, heating to 300 ℃ and reacting for 60min to obtain the CdZnSe/ZnSe quantum dot, wherein the total thickness of the ZnSe shell layer is 9nm.
Example 6:
0.1mmol of cadmium oleate, 0.2mmol of oleic acid, 10g of ODE and nitrogen atmosphere are weighed into a three-port bottle, the temperature is raised to 250 ℃, then 0.1mL of 0.5mmol/mL Se-ODE and 0.1mL of 0.5mmol/mL S-ODE mixed solution are injected, and the reaction is carried out for 10min at 240 ℃, so as to obtain the CdSeS quantum dot with the concentration of 3.2 nm.
Under the protection of nitrogen, 4mmol of zinc acetate and 10mmol of oleic acid are added through a funnel without purifying the CdSeS quantum dot solution, and then nitrogen is introduced for 20min after the temperature is raised to 200 ℃. Then 1.0mL of 3mmol/mL Se-TBP solution is added into the solution, the temperature is quickly raised to 310 ℃ for reaction for 60min, and the CdSeS/ZnSe quantum dot intermediate solution is obtained, wherein the thickness of a ZnSe shell layer is 1.5nm.
Under the protection of nitrogen, 3mmol of zinc acetate and 10mmol of oleic acid are added through a funnel without purifying the CdSeS/ZnSe quantum dot intermediate solution, and then nitrogen is introduced for 30min after the temperature is raised to 180 ℃. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain CdSeS/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 2.5nm.
The CdSeS/ZnSe quantum dot intermediate solution is not purified, 4mmol of zinc propionate and 10mmol of oleic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 180 ℃. And then adding 1.33mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain CdSeS/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 4nm.
Under the protection of nitrogen, 5mmol zinc propionate and 10mmol oleic acid are added through a funnel without purification of the CdSeS/ZnSe quantum dot intermediate solution, and then nitrogen is introduced for 30min after the temperature is raised to 180 ℃. And then adding 1.33mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 60min to obtain CdSeS/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 5.5nm.
Under the protection of nitrogen, 5mmol zinc propionate and 10mmol oleic acid are added through a funnel without purification of the CdSeS/ZnSe quantum dot intermediate solution, and then nitrogen is introduced for 30min after the temperature is raised to 180 ℃. And then adding 1.66mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 20min to obtain the CdSeS/ZnSe quantum dot, wherein the thickness of a ZnSe shell layer is 7nm.
Example 7:
0.2mmol of cadmium oleate, 2mmol of zinc oleate and 10g of ODE are weighed into a three-necked flask, the temperature is raised to 290 ℃ under the protection of nitrogen atmosphere, then 1.0mL of 0.5mmol/mL of Se-ODE is injected, and the temperature is raised to 300 ℃ for reaction for 5min. Then adding 1.0mL of 0.5mmol/mL Se-TBP, reacting for 20min at 300 ℃, and cooling to room temperature to obtain 3.0nm CdZnSe quantum dot solution.
Under the protection of nitrogen, 3mmol of zinc acetate and 6mmol of oleic acid are added through a funnel without purifying the CdZnSe quantum dot solution, and then nitrogen is introduced for 20min after the temperature is raised to 150 ℃. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 20min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer is 1.5nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 3mmol of zinc acetate and 8mmol of oleic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 150 ℃. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 3nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 4mmol of zinc propionate and 10mmol of oleic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 180 ℃. And then adding 1.33mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 4.5nm.
Under the protection of nitrogen, 5mmol of zinc acetate and 10mmol of oleic acid are added through a funnel without purifying the CdZnSe/ZnSe quantum dot intermediate solution, and then nitrogen is introduced for 30min after the temperature is raised to 150 ℃. And then adding 1.33mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 6nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 6mmol of zinc acetate and 12mmol of oleic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 180 ℃. And then adding 1.67mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 60min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 7.5nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 6mmol of zinc formate and 12mmol of oleic acid are added through a funnel under the protection of nitrogen, and then the temperature is raised to 120 ℃ and nitrogen is introduced for 30min. Then adding 2.0mL of 3mmol/mL Se-TBP solution into the solution, heating to 300 ℃ and reacting for 60min to obtain the CdZnSe/ZnSe quantum dot, wherein the total thickness of the ZnSe shell layer is 9nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, 6mmol of zinc acetate and 12mmol of oleic acid are added through a funnel under the protection of nitrogen, and then nitrogen is introduced for 30min after the temperature is raised to 150 ℃. Then 2.0mL of 3mmol/mL Se-TBP solution is added into the solution, the temperature is raised to 300 ℃ for reaction for 60min, and the CdZnSe/ZnSe quantum dot shown in the figure 3 is obtained, wherein the total thickness of a ZnSe shell layer is 10nm.
Comparative example 1:
0.2mmol of cadmium oleate, 2mmol of zinc oleate and 10g of ODE are weighed into a three-necked flask, the temperature is raised to 280 ℃ under the protection of nitrogen atmosphere, then 1.0mL of 0.5mmol/mL Se-ODE is injected, and the temperature is raised to 300 ℃ for reaction for 10min. Then adding 0.33mL of 3mmol/mL Se-TBP, reacting for 20min at 300 ℃, and cooling to room temperature to obtain a CdZnSe quantum dot solution of 4.0 nm.
Under the protection of nitrogen, 8mmol of zinc acetate and 20mmol of oleic acid are added through a funnel without purifying the CdZnSe quantum dot solution, and then nitrogen is introduced for 30min after the temperature is raised to 150 ℃. Then adding 2.0mL of 3mmol/mL Se-TBP solution into the solution, heating to 300 ℃ and reacting for 60min to obtain the CdZnSe/ZnSe quantum dot, wherein the thickness of the ZnSe shell layer is 3nm.
Comparative example 2:
0.18mmol of cadmium oleate, 2mmol of zinc oleate and 10g of ODE are weighed into a three-necked flask, the temperature is raised to 280 ℃ under the protection of nitrogen atmosphere, 1.2mL of 0.5mmol/mL of Se-ODE is injected, and the temperature is raised to 300 ℃ for reaction for 20min. Then 0.4mL of 2mmol/mL Se-TBP solution is added, the reaction is carried out for 30min at 300 ℃, and the temperature is reduced to the room temperature, thus obtaining the CdZnSe quantum dot solution with the wavelength of 3.6 nm.
Under the protection of nitrogen, 15mmol of zinc acetate and 30mmol of oleic acid are added through a funnel, and then the temperature is raised to 180 ℃ and nitrogen is introduced for 20min. And then adding 4.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 60min to obtain the CdZnSe/ZnSe quantum dot, wherein the thickness of a ZnSe shell layer is 5nm.
Comparative example 3:
0.18mmol of cadmium oleate, 2mmol of zinc oleate and 10g of ODE are weighed into a three-necked flask, the temperature is raised to 280 ℃ under the protection of nitrogen atmosphere, 1.2mL of 0.5mmol/mL of Se-ODE is injected, and the temperature is raised to 300 ℃ for reaction for 20min. Then 0.4mL of 2mmol/mL Se-TBP solution is added, the reaction is carried out for 30min at 300 ℃, and the temperature is reduced to the room temperature, thus obtaining the CdZnSe quantum dot solution with the wavelength of 3.6 nm.
Under the protection of nitrogen, 8mmol of zinc acetate and 20mmol of oleic acid are added through a funnel, and then the temperature is raised to 180 ℃ and nitrogen is introduced for 20min. And then adding 1.67mL of 3mmol/mL Se-TBP solution into the solution, heating to 300 ℃, and reacting for 60min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer is 2.4nm.
Under the protection of nitrogen, 8mmol of zinc acetate and 16mmol of oleic acid are added through a funnel without purifying the CdZnSe/ZnSe quantum dot intermediate solution, and then the temperature is raised to 180 ℃ and nitrogen is introduced for 20min. Then adding 2.33mL of 3mmol/mL Se-TBP solution into the solution, heating to 300 ℃, and reacting for 60min to obtain the CdZnSe/ZnSe quantum dot, wherein the total thickness of a ZnSe shell layer is 5nm.
Comparative example 4:
0.2mmol of cadmium myristate, 2mmol of zinc stearate and 10g of ODE are weighed into a three-necked flask, the temperature is raised to 290 ℃ under the protection of nitrogen atmosphere, then 1.0mL of 0.5mmol/mL Se-ODE is injected, and the temperature is raised to 300 ℃ for reaction for 5min. Then 1.0mL of 0.5mmol/mL Se-TBP is added, the reaction is carried out for 20min at 300 ℃, and the temperature is reduced to the room temperature, thus obtaining the CdZnSe quantum dot solution with the concentration of 3.0 nm.
Purifying the CdZnSe quantum dot solution, then dispersing in 12g ODE again, adding 4mmol of zinc acetate and 10mmol of oleic acid through a funnel under the protection of nitrogen, and then heating to 200 ℃ and introducing nitrogen for 20min. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 20min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer is 1.5nm.
Purifying the CdZnSe/ZnSe quantum dot intermediate solution, then re-dispersing in 12g ODE, adding 3mmol of zinc acetate and 10mmol of oleic acid through a funnel under the protection of nitrogen, and then heating to 180 ℃ and introducing nitrogen for 30min. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 3nm.
Purifying the CdZnSe/ZnSe quantum dot intermediate solution, then re-dispersing in 15g ODE, adding 4mmol zinc propionate and 10mmol oleic acid through a funnel under the protection of nitrogen, and then heating to 180 ℃ and introducing nitrogen for 30min. And then adding 1.33mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 4.5nm.
Purifying the CdZnSe/ZnSe quantum dot intermediate solution, then re-dispersing in 15g ODE, adding 5mmol zinc propionate and 10mmol oleic acid through a funnel under the protection of nitrogen, and then heating to 180 ℃ and introducing nitrogen for 30min. And then adding 1.33mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 60min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 6nm.
Purifying the CdZnSe/ZnSe quantum dot intermediate solution, then re-dispersing in 20g ODE, adding 3mmol zinc propionate and 6mmol oleic acid through a funnel under the protection of nitrogen, and then heating to 180 ℃ and introducing nitrogen for 30min. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 20min to obtain the CdZnSe/ZnSe quantum dot, wherein the total thickness of a ZnSe shell layer is 7nm.
Comparative example 5:
0.2mmol of cadmium oleate, 2mmol of zinc oleate and 10g of ODE are weighed into a three-necked flask, the temperature is raised to 290 ℃ under the protection of nitrogen atmosphere, then 0.5mmol of Se-ODE is injected, and the temperature is raised to 300 ℃ for reaction for 5min. Then 1mL of 0.5mmol/mL Se-TBP solution is added, the reaction is carried out for 20min at 300 ℃, and the temperature is reduced to the room temperature, thus obtaining the CdZnSe quantum dot solution with the concentration of 3.0 nm.
The CdZnSe quantum dot solution is not purified, and 4mmol of zinc oleate and 2mmol of oleic acid are added through a funnel under the protection of nitrogen. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 20min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer is 1.5nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, and 3mmol of zinc oleate is added through a funnel under the protection of nitrogen. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 3nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, and 4mmol of zinc oleate and 2mmol of oleic acid are added through a funnel under the protection of nitrogen. And then adding 1.33mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 40min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 4.5nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, and 3mmol of zinc oleate is added through a funnel under the protection of nitrogen. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 60min to obtain a CdZnSe/ZnSe quantum dot intermediate solution, wherein the thickness of a ZnSe shell layer reaches 5.8nm.
The CdZnSe/ZnSe quantum dot intermediate solution is not purified, and 3mmol of zinc oleate is added through a funnel under the protection of nitrogen. And then adding 1.0mL of 3mmol/mL Se-TBP solution into the solution, and heating to 300 ℃ to react for 30min to obtain the CdZnSe/ZnSe quantum dot, wherein the total thickness of a ZnSe shell layer is 7nm.
The core-shell Quantum dots of examples 1 to 7 and comparative examples 1 to 5 were fabricated into optoelectronic devices having the structure ITO/PEDOTS: PSS/TFB/Quantum dots/ZnMgO/Al, and the specific preparation method was as follows:
cleaning of ITO glass
The ITO glass piece with the number carved on the back is put into a glass dish filled with ethanol solution, and the ITO surface is scrubbed by a cotton swab. Sequentially ultrasonic treating with acetone, deionized water and ethanol for 10min, and blow-drying with nitrogen gun. Finally, the cleaned ITO glass sheet is placed in oxygen plasma for further cleaning for 10 minutes.
2. Hole injection layer
And spin-coating PEDOTS (periodic Table of the present invention) on the cleaned ITO glass sheet in air respectively, wherein the rotation speed is 3000r/min, and the spin-coating time is 45 seconds. And after spin coating, placing in air for annealing at 150 ℃ for 30 minutes. After the annealing was completed, the tablets were quickly transferred to a glove box under nitrogen atmosphere.
3. Hole transport layer
The ITO/PEDOTS/PSS chip is continuously coated with a hole transport layer of 8-10mg/mL TFB in a spin mode, the rotating speed is 2000r/min, and the spin time is 45 seconds. Annealing in a glove box after spin coating is completed, wherein the annealing temperature is 150 ℃ and the annealing time is 30 minutes.
4. Quantum dot luminescent layer
The core-shell quantum dot has optical concentration of 30-40 at 350nm and is dissolved in octane solvent. And continuously spin-coating the quantum dot solution after finishing annealing the ITO/PEDOTS/PSS/TFB flakes, wherein the spin-coating rotating speed is 2000r/min, and the spin-coating time is 45 seconds. After spin coating is completed, the next layer can be spin coated without annealing.
5. Electron transport layer
Spin coating of MgZnO nanocrystals (30 mg/mL, ethanol solution): the ITO/PEDOTS, PSS/TFB/Quantum dots are spin-coated with MgZnO nanocrystalline solution at a rotation speed of 2000r/min for 45 seconds.
Al electrode
And placing the prepared sample slice into a vacuum cavity, and evaporating a top electrode. The evaporation rate is controlled at the first 10nm
Figure BDA0002282646860000201
Within the range, the evaporation rate after 10nm is improved to +.>
Figure BDA0002282646860000202
Left and right. The thickness of the aluminum electrode was 100nm.
The performance of the photovoltaic devices made of the core-shell quantum dots of examples 1 to 7 and comparative examples 1 to 5 was tested, and the results are shown in table 1.
TABLE 1
Figure BDA0002282646860000211
As can be seen from Table 1, the blue light quantum dots with core-shell structures are obtained by coating ZnSe shell layers for multiple times, so that on one hand, the HOMO of the blue light quantum dots with core-shell structures is improved, the energy level difference between the blue light quantum dots and the TFB hole transport layer is reduced, the injection of carriers is facilitated, on the other hand, the size of the blue light quantum dots is increased, the non-radiative Auger recombination among the blue light quantum dots is reduced, and the light efficiency of the light emitting layer is improved. Therefore, the photoluminescence efficiency of the blue light quantum dot with the core-shell structure is higher, qys is close to 100%, the electroluminescence effect is obviously improved, and particularly when the ZnSe thickness is larger than 5nm, the service life of a blue light device is close to 10000 hours, which is far higher than experimental data of a comparative example.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (9)

1. The preparation method of the core-shell quantum dot is characterized by comprising the following steps:
(1) Providing a solution containing quantum dots, wherein the solution containing quantum dots is a raw material for preparing core-shell quantum dots;
(2) Mixing the raw materials for preparing the core-shell quantum dot with short-chain fatty acid zinc with the carbon chain length of less than or equal to 8 and long-chain fatty acid with the carbon chain length of more than or equal to 12, and reacting at a first temperature to obtain an intermediate solution, wherein the molar ratio of the long-chain fatty acid to the short-chain fatty acid zinc is more than or equal to 2:1;
(3) Mixing the intermediate solution with a precursor containing Se elements, and reacting at a second temperature to coat ZnSe shell layers with the thickness less than or equal to 1.5nm on the surfaces of the quantum dots, thereby obtaining a solution containing core-shell quantum dot intermediates;
(4) And (3) taking the solution containing the core-shell quantum dot intermediate as a raw material for preparing the core-shell quantum dot in the step (1), and coating the core-shell quantum dot by repeating the steps (2) and (3) at least once to obtain the core-shell quantum dot containing the ZnSe shell layer with the total thickness of 3-10 nm.
2. The method for preparing core-shell quantum dots according to claim 1, wherein the thickness of the ZnSe shell layer obtained by single cladding in the step (3) is 0.5nm to 1.5nm.
3. The method for preparing the core-shell quantum dot according to claim 1, wherein the molar ratio of the long-chain fatty acid to the short-chain fatty acid zinc is 2:1-4:1.
4. The method of preparing core-shell quantum dots according to claim 1, wherein the first temperature is 100 ℃ to 240 ℃ and the second temperature is 280 ℃ to 310 ℃.
5. The method for preparing the core-shell quantum dot according to claim 1, wherein the molar ratio of Se element to Zn element is 1:2-2:1, and the molar concentration of Se element in the precursor containing Se element is 0.5-4 mmol/mL.
6. The method for preparing the core-shell quantum dot according to claim 1, wherein the solution containing the quantum dot is a product system containing the quantum dot synthesized by a solution method.
7. The method of claim 1, wherein the quantum dots comprise at least one of CdZnSeS, cdSe, cdZnSe, znSe, cdSeS, inP, inZnP.
8. A quantum dot composition comprising core-shell quantum dots prepared by the method of any one of claims 1 to 7.
9. An optoelectronic device comprising the core-shell quantum dot prepared by the method of any one of claims 1 to 7.
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