Core-shell quantum dot, composition containing core-shell quantum dot, and photoluminescent device containing core-shell quantum dot
By designing the energy level structure of core-shell quantum dots to isolate excitons from the external environment, the problem of quantum dot instability under illumination was solved, achieving high stability and excellent optical performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NAJING TECHNOLOGY CORPORATION LIMITED
- Filing Date
- 2024-10-22
- Publication Date
- 2026-04-24
AI Technical Summary
Existing core-shell quantum dots are not stable enough under light conditions and are prone to photo-oxidation and photo-hydrolysis, which affects display performance.
Design a core-shell quantum dot structure, in which the core and shell layers consist of a quantum dot core, N shells, and M shells from the inside out. The band widths of the N shells gradually decrease, with the luminescent shell having the smallest band width. The valence band and conduction band of the N shells gradually increase and decrease along the direction away from the quantum dot core, thus isolating the excitons from contact with the external environment.
This improves the light stability of quantum dots while maintaining excellent optical performance and enhances their environmental stability.
Smart Images
Figure CN121914710A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of quantum dot technology, and more specifically, to a core-shell quantum dot and a composition containing the same, and a photoluminescent device. Background Technology
[0002] The application of quantum dots in displays often involves exciting red and green quantum dots with a blue backlight to achieve red and green light emission, thereby enabling high color gamut and high purity in the display. This requires quantum dots to possess high light stability. The essence of light stability is the resistance of quantum dots to water and oxygen. Under light conditions, water and oxygen in the air can damage quantum dots, causing photo-oxidation and photo-hydrolysis processes. According to literature reports (J. Am. Chem. Soc. 2021, 143, 44, 18721–18732; J. Am. Chem. Soc. 2023, 145, 25, 13938–13949), in the presence of both water and oxygen, electrons in the CdSe / CdS and CdSe / ZnSe shells (electrons in the CdS and ZnSe shells, respectively) are excited during blue light excitation. These electrons combine with water and oxygen in the air to form oxygen free radical anions and hydroxyl free radicals, which then react with metal carboxylates, metal cations, and anions on the quantum dot surface to form inorganic acid metal salts, thus initiating the quantum dot etching process. Improving the light-induced stability of quantum dots has become a key issue for quantum dot display applications. Summary of the Invention
[0003] The purpose of this disclosure is to provide a core-shell quantum dot and a composition containing the same, as well as a photoluminescent device, to solve the problem of insufficient light stability of existing core-shell quantum dots.
[0004] According to a first aspect of this disclosure, a core-shell quantum dot is provided, comprising, from the inside out, a quantum dot core, N shells, a luminescent shell, and M shells, where N is an integer greater than or equal to 3 and M is an integer greater than or equal to 2. The luminescent shell has the smallest band width. The valence bands of the N shells gradually increase in the direction away from the quantum dot core, and the conduction bands of the N shells gradually decrease in the direction away from the quantum dot core. The conduction band of the Nth shell is lower than the conduction band corresponding to the smallest band width among the M shells, and the valence band of the Nth shell is higher than the valence band corresponding to the smallest band width among the M shells.
[0005] Optionally, the size of the core-shell quantum dot is larger than the Bohr exciton diameter of the luminescent shell. Preferably, the thickness of the N shells is independently selected from 0.5-3 nm.
[0006] Optionally, the band width of the M shells gradually increases along the direction away from the quantum dot nucleus.
[0007] Optionally, the core-shell quantum dots include cadmium, zinc, sulfur, and selenium; optionally, the core-shell quantum dots also include tellurium; optionally, each of the N shells contains three elements or each contains four elements.
[0008] Optionally, the core-shell quantum dots are CdS / CdSeS / CdSeS / CdSeS / CdSe / CdZnS / ZnS, CdS / CdSeS / CdSeS / CdSeS / CdSe / CdS / CdZnS / ZnS, ZnS / CdZnS / CdS / CdSe / CdZnS / ZnS, ZnS / CdZnS / CdS / CdSeS / Cd Se / CdZnS / ZnS, ZnS / CdZnS / CdS / CdSeS / CdSe / CdS / CdZnS / ZnS, CdS / CdSeS / CdSeS / C dSeS / CdSe / CdS / CdZnS / ZnS, ZnS / ZnSeS / CdZnSe / ZnSe / CdSe / CdZnS / ZnS, ZnS / ZnSeS / ZnSe / CdZnSe / CdSe / CdZnSe / CdZnS / ZnS、ZnS / ZnSeS / ZnSe / CdZnSe / CdSe / CdZnSe / ZnSe / CdZnS / ZnS, ZnS / ZnSeS / ZnSe / CdZnSe / CdSe / CdZnSe / ZnSe / ZnSeS / ZnS, ZnS / Cd ZnS / CdS / CdSeS / CdSe / CdSeS / CdS / CdZnS / ZnS、CdS / CdSeS / CdSeS / CdSeS / CdSe / CdS , ZnS / CdZnS / CdS / CdSeS / CdSeS / CdS / CdZnS / ZnS, ZnS / ZnSeS / ZnSe / CdSe / CdZnS / ZnS ZnS / CdS / CdSeS / CdSe / CdS / CdZnS / ZnS, ZnS / ZnSeS / ZnSe / CdZnSe / CdTe / CdZnS / ZnS, ZnS / Z nSeS / ZnSe / CdZnSe / CdTe / ZnSeS / ZnS or ZnS / ZnSeS / ZnSe / CdZnSe / CdTe / ZnSeS / CdZnS / ZnS.
[0009] Optionally, the N shells have the same constituent elements, but the element ratios of each shell are different; preferably, the sum of M and N is less than or equal to 10, more preferably, N is less than or equal to 6 and M is less than or equal to 4.
[0010] Optionally, the difference between the valence band energy level corresponding to the smallest band width among the N shells and the smallest band width among the M shells is less than 0.5 eV, and the difference between the conduction band energy level corresponding to the smallest band width among the N shells and the smallest band width among the M shells is less than 1.5 eV.
[0011] Optionally, the fluorescence half-width of the core-shell quantum dots is less than or equal to 35 nm, and the quantum yield of the core-shell quantum dots is greater than or equal to 75%.
[0012] According to a second aspect of this disclosure, a quantum dot composition is provided, comprising any core-shell quantum dot.
[0013] According to a third aspect of this disclosure, a quantum dot photoluminescent device is provided, comprising any core-shell quantum dot.
[0014] By applying the above technical solution, core-shell quantum dots with the above energy level structure have excellent light stability while maintaining the excellent optical performance of quantum dots. Attached Figure Description
[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure. In the drawings:
[0016] Figure 1 This is a schematic diagram of the core-shell quantum dot energy level structure of some embodiments of this disclosure.
[0017] Figure 2 This is an electron microscope image of a core-shell quantum dot according to an embodiment of the present disclosure.
[0018] Figure 3 These are comparative photographs of quantum dot toluene solutions after aging, representing an embodiment and a comparative example of this disclosure.
[0019] Figure 4 The fluorescence emission spectrum of a quantum dot photoluminescent device according to an embodiment of the present disclosure changes with aging time under specific aging conditions.
[0020] Figure 5 The fluorescence emission spectrum of a quantum dot photoluminescent device according to another embodiment of this disclosure changes with aging time under specific aging conditions.
[0021] Figure 6 The fluorescence emission spectrum of a pair of quantum dot photoluminescent devices disclosed herein under specific aging conditions varies with aging time.
[0022] Figure 7This is another comparative example of the fluorescence emission spectrum of a quantum dot photoluminescent device under specific aging conditions, showing the change of fluorescence emission spectrum with different aging times. Note that in the embodiments described below, the same reference numerals are sometimes used across different figures to denote the same parts or parts having the same function, and repeated descriptions are omitted. In some cases, similar reference numerals and letters are used to denote similar items, so once an item is defined in one figure, it does not need to be discussed further in subsequent figures. For ease of understanding, the positions, dimensions, and extents of the structures shown in the accompanying drawings and other materials may not represent actual positions, dimensions, and extents. Therefore, this disclosure is not limited to the positions, dimensions, and extents disclosed in the accompanying drawings and other materials. Detailed Implementation
[0023] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the present disclosure.
[0024] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this disclosure or its application or use. That is, the structures and methods herein are shown in an exemplary manner to illustrate different embodiments of the structures and methods in this disclosure. However, those skilled in the art will understand that they merely illustrate exemplary ways that can be used to implement this disclosure, and not exhaustive ways. Furthermore, the drawings are not necessarily drawn to scale, and some features may be enlarged to show details of specific components.
[0025] In addition, techniques, methods and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods and equipment should be considered part of the specification.
[0026] In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.
[0027] Additionally, terms such as “first,” “second,” etc., may be used in this document for reference purposes only and are not intended to be limiting. For example, unless the context clearly indicates otherwise, the words “first,” “second,” and other such numerical terms relating to structures or elements do not imply order or sequence.
[0028] It should also be understood that when the term “including / contains” is used herein, it indicates the presence of the indicated feature, whole, step, operation, unit and / or component, but does not preclude the presence or addition of one or more other features, wholes, steps, operations, units and / or components and / or combinations thereof.
[0029] In this disclosure, the term “provide” is used broadly to cover all ways of obtaining an object, and therefore “provide an object” includes, but is not limited to, “purchasing,” “preparing / manufacturing,” “arranging / setting up,” “installing / assembling,” and / or “ordering” an object.
[0030] As used herein, the term “and / or” includes any and all combinations of one or more of the listed items in association. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise.
[0031] In existing technologies, the main method to obtain quantum dots with high water and oxygen stability is to coat them with a thick shell. The inventors believe that this method does not take into account the lattice stress and internal defects it brings, which makes the optical performance of quantum dots worse. Although the environmental stability (resistance to water, oxygen, and light) is improved, it is only partially alleviated and cannot be maintained for a long time.
[0032] Through the inventors' reflection and practice, it was found that to obtain quantum dots with high stability and excellent optical properties under light illumination, it is necessary to isolate the electrons or holes in the shell excitons from the water and oxygen in the external environment. When irradiated with blue light, electrons in the nucleus (light-emitting part) are excited to form electron-hole pairs. Due to the quantum confinement effect, it is traditionally believed that these electron-hole pairs will diffuse into the shell. However, if the overall size of the core-shell quantum dot is smaller than the diameter of the Bohr exciton in the nucleus (light-emitting part), then the electrons and holes formed by exciting the nucleus (light-emitting part) will come into contact with oxygen and water in the external environment, thereby causing photo-oxidation and photo-hydrolysis processes. Based on this, the inventors proposed a new approach: first, a quantum dot (containing a quantum dot core and N shells) with a larger band width than the luminescent part is formed before the luminescent part. The band width of the N shells of this quantum dot gradually decreases but is still larger than that of the luminescent part. Then, the luminescent part (i.e., the luminescent shell) is grown again, and then a subsequent shell structure (M shells) is wrapped on it. After the luminescent shell is excited, the excitons can diffuse inward instead of outward in the traditional sense, thereby isolating the excitons from the environment and realizing an environmentally stable core-shell quantum dot. Therefore, to address the problem of quantum dot instability under illumination, this disclosure proposes a core-shell quantum dot. The core-shell quantum dot, from the inside out, comprises a quantum dot core, N shells, a luminescent shell, and M shells, where N is an integer greater than or equal to 3 and M is an integer greater than or equal to 1. The smallest band width among the N shells is smaller than the smallest band width among the M shells. The luminescent shell has the smallest band width. The valence band of the N shells gradually increases away from the quantum dot core, and the conduction band of the N shells gradually decreases away from the quantum dot core. The conduction band of the Nth shell is lower than the conduction band corresponding to the largest band width among the M shells, and the valence band of the Nth shell is higher than the valence band corresponding to the smallest band width among the M shells. Due to this energy level structure design, electrons and holes in the luminescent shell preferentially diffuse inward, consuming some energy, thus greatly reducing the probability of subsequent outward diffusion. The core-shell quantum dot with this structure exhibits excellent quantum dot illumination stability while maintaining the superior optical performance of the quantum dot.
[0033] It should be noted that the quantum dot core and all shells are semiconductor materials. Those skilled in the art can determine the band width or its relative size based on the elemental composition and proportions of the quantum dot core and shell materials.
[0034] In some embodiments, N = M = 3, and the schematic diagram of the energy level structure of the core-shell quantum dot is shown below. Figure 1 As shown, the area circled in dashed lines represents the light-emitting shell, with the valence band at the bottom and the conduction band at the top.
[0035] In some embodiments, the size of the core-shell quantum dot is larger than the diameter of the Bohr exciton in the luminescent shell. This results in higher optical stability of the quantum dot.
[0036] In some embodiments, the thickness of the N shells is independently selected from 0.5-3 nm. If the shell thickness is too large, the morphology of the quantum dots is prone to change, which can easily affect the coating of subsequent luminescent shells.
[0037] In some embodiments, the band width of the M shells gradually increases along the direction away from the quantum dot core. This allows electrons or holes in the luminescent shells to diffuse more easily into the core-shell quantum dot in front of the luminescent shell.
[0038] In some embodiments, the valence bands of the M shells gradually decrease along the direction away from the quantum dot nucleus, and the conduction bands of the M shells gradually increase along the direction away from the quantum dot nucleus.
[0039] In some embodiments, the core-shell quantum dots include cadmium, zinc, sulfur, and selenium. In some embodiments, the core-shell quantum dots also include tellurium. In some embodiments, each of the N shells contains three elements or each contains four elements.
[0040] In some embodiments, the core-shell quantum dots are CdS / CdSeS / CdSeS / CdSeS / CdSe / CdZnS / ZnS, CdS / CdSeS / CdSeS / CdSe / CdS / CdZnS / ZnS, ZnS / CdZnS / CdS / CdSe / CdZnS / ZnS, ZnS / CdZnS / CdS / CdSeS / CdSe / CdZnS / ZnS, ZnS / CdZnS / CdS / CdSeS / CdSe / CdZnS / ZnS, Zn S / CdZnS / CdS / CdSeS / CdSe / CdS / CdZnS / ZnS, CdS / CdSeS / CdSeS / CdSeS / CdSe / CdS / CdZnS / ZnS, Z nS / ZnSeS / CdZnSe / ZnSe / CdSe / CdZnS / ZnS、ZnS / ZnSeS / ZnSe / CdZnSe / CdSe / CdZnSe / CdZnS / ZnS , ZnS / ZnSeS / ZnSe / CdZnSe / CdSe / CdZnSe / ZnSe / CdZnS / ZnS, ZnS / ZnSeS / ZnSe / CdZnSe / CdSe / CdZnSe / ZnSe / ZnSeS / ZnS, ZnS / CdZnS / CdS / CdSeS / CdSe / CdSeS / CdS / CdZnS / ZnS, CdS / CdSeS / CdSeS / CdSeS / CdSe / CdS、ZnS / CdZnS / CdS / CdSeS / CdSeS / CdS / CdZnS / ZnS、ZnS / ZnSeS / ZnSe / CdSe / CdZnS / ZnS、ZnS / CdS / CdSeS / CdSe / CdS / The quantum dots CdZnS / ZnS, ZnS / ZnSeS / ZnSe / CdZnSe / CdTe / CdZnS / ZnS, or ZnS / ZnSeS / ZnSe / CdZnSe / CdTe / ZnSeS / ZnS, ZnS / ZnSeS / ZnSe / CdZnSe / CdTe / ZnSeS / CdZnS / ZnS, among which only the ZnS / CdZnS / CdS / CdSeS / CdSeS / CdZnS / ZnS quantum dots have a CdSeS luminescent shell, the last three have a CdTe luminescent shell, and the remaining core-shell quantum dots have a CdSe luminescent shell.
[0041] In some embodiments, the N shells have the same constituent elements, but the element ratios of each shell are different. In some embodiments, the sum of M+N is less than or equal to 10, reducing the cost of core-shell quantum dot fabrication while also reducing the degradation of optical performance. In some embodiments, the sum of M+N is less than or equal to 8. In some embodiments, more preferably, N is less than or equal to 6 and M is less than or equal to 4.
[0042] In some embodiments, the difference between the valence band energy level corresponding to the smallest band width among the N shells and the smallest band width among the M shells is less than 0.5 eV, and the difference between the conduction band energy level corresponding to the smallest band width among the N shells and the smallest band width among the M shells is less than 1.5 eV.
[0043] In some embodiments, the fluorescence half-width at half-maximum (FWHM) of the core-shell quantum dots is less than or equal to 35 nm, and the quantum yield of the core-shell quantum dots is greater than or equal to 75%. In some embodiments, the fluorescence FWHM of the core-shell quantum dots is less than or equal to 30 nm, and the quantum yield of the core-shell quantum dots is greater than or equal to 75%. In some embodiments, the fluorescence FWHM of the core-shell quantum dots is less than or equal to 30 nm and greater than or equal to 20 nm, and the quantum yield of the core-shell quantum dots is greater than or equal to 75% and less than or equal to 85%. In some embodiments, the fluorescence FWHM of the core-shell quantum dots is less than or equal to 30 nm and greater than or equal to 20 nm, and the quantum yield of the core-shell quantum dots is greater than or equal to 75% and less than or equal to 90%.
[0044] This disclosure also provides a quantum dot composition comprising any of the above-described core-shell quantum dots. This quantum dot composition exhibits excellent environmental stability.
[0045] This disclosure also provides a quantum dot photoluminescent device comprising any of the above-described core-shell quantum dots. This quantum dot photoluminescent device exhibits excellent environmental stability.
[0046] The implementation methods are described in more detail below with reference to specific embodiments. However, these are exemplary examples of the present disclosure, and the present disclosure is not limited thereto.
[0047] Preparation of reaction precursors
[0048] Preparation of 0.1 mmol / mL selenium powder suspension (Se-SUS): Disperse selenium powder (0.0237 g, 0.3 mmol, 100 or 200 mesh) in 3 mL of ODE and sonicate for 5 minutes to prepare a 0.1 mmol / mL suspension. The preparation of selenium powder suspensions of other concentrations is similar, only the amount of selenium powder needs to be changed. Shake well by hand before use.
[0049] Preparation of 2 mmol / mL Se-TBP solution: Weigh 1.58 g of Se, place it in a 20 mL glass bottle with a rubber stopper and seal it. Use an inert gas to purge the air from the bottle, inject 10 mL of TBP, and repeatedly shake and sonicate the mixture until the Se is completely dissolved.
[0050] Preparation of 2 mmol / mL S-TBP solution: Weigh 0.64 g of Se, place it in a 20 mL glass bottle with a rubber stopper and seal it. Use an inert gas to purge the air from the bottle, inject 10 mL of TBP, and repeatedly shake and sonicate the mixture until the S is completely dissolved.
[0051] Example 1: Synthesis of CdS / CdSeS / CdSeS / CdSeS / CdSeS / CdSe / CdZnS / ZnS core-shell quantum dots:
[0052] Synthesis of CdS / CdSeS / CdSeS / CdSeS / CdSe quantum dots: CdO (0.0256 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the mixture was heated to 280 °C to obtain a clear solution, which was then cooled to 250 °C. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the three-necked flask, and the reaction temperature was maintained at 250 °C. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of 0.05 mmol / mL selenium powder suspension and 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension and 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Then, inject 1 mL of 0.2 mmol / mL cadmium oleate solution, warm to room temperature, and then every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension and 0.05 mmol / mL S-ODE into the three-necked flask, repeating twice. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating twice. Finally, immediately stop heating.
[0053] Weigh 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified CdS / CdSeS / CdSeS / CdSeS / CdSe quantum dot solution with a first exciton absorption peak absorbance of 50. Raise the temperature to 300 °C. Add 1 mL of a mixture of cadmium oleate and 1 mL of S-TBP at a rate of 5 mL / h, followed by 4 mL of S-TBP solution at a rate of 5 mL / h. After the addition is complete, cool down to stop the reaction, yielding the desired quantum dots. See the electron micrograph for details. Figure 2 .
[0054] Example 2: Synthesis of CdS / CdSeS / CdSeS / CdSeS / CdSeS / CdSe / CdS / CdZnS / ZnS core-shell quantum dots:
[0055] Synthesis of CdS / CdSeS / CdSeS / CdSeS / CdSe / CdS quantum dots: CdO (0.0256 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the mixture was heated to 280 °C to obtain a clear solution, which was then cooled to 250 °C. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the three-necked flask, and the reaction temperature was maintained at 250 °C. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of 0.05 mmol / mL selenium powder suspension and 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension and 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Next, inject 1 mL of 0.2 mmol / mL cadmium oleate solution, allow to warm, and then every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating twice. Finally, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating twice. A 0.1 mmol / mL S-ODE solution was added, and the reaction was carried out for 10 minutes, after which heating was immediately stopped.
[0056] Weigh 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified CdS / CdSeS / CdSeS / CdSeS / CdSe / CdS quantum dot solution with a first exciton absorption peak absorbance of 50. Raise the temperature to 300 °C. Add 1 mL of a mixture of cadmium oleate and 1 mL of S-TBP at a rate of 5 mL / h, followed by 4 mL of S-TBP solution at a rate of 5 mL / h. After the addition is complete, cool down to stop the reaction, thus obtaining the desired quantum dots.
[0057] Example 3 Synthesis of ZnS / CdZnS / CdS / CdSe / CdZnS / ZnS core-shell quantum dots
[0058] Synthesis of ZnS / CdS / CdSe quantum dots: ZnO (0.016 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the mixture was heated to 300 °C to obtain a clear solution. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the flask, and the reaction temperature was maintained at 300 °C. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of a mixed solution of 0.2 mmol / mL cadmium oleate and 0.1 mmol / mL S-ODE into the three-necked flask. React for another 5 minutes, then cool to 250°C and inject 1 mL of 0.2 mmol / mL cadmium oleate solution. Allow the mixture to warm to room temperature. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Next, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating twice. React for 10 minutes, then immediately stop heating.
[0059] Weigh 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified ZnS / CdS / CdS / CdSe quantum dot solution with an absorbance of 50 at the first exciton absorption peak. Raise the temperature to 300 °C. Add 1 mL of a mixture of cadmium oleate and 1 mL of S-TBP at a rate of 5 mL / h, followed by 4 mL of S-TBP solution at a rate of 5 mL / h. After the addition is complete, cool down to stop the reaction, thus obtaining the desired quantum dots.
[0060] Example 4: Synthesis of ZnS / CdZnS / CdS / CdSeS / CdSe / CdZnS / ZnS core-shell quantum dots
[0061] Synthesis of ZnS / CdS / CdS / CdSe quantum dots: ZnO (0.016 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the temperature was raised to 300 °C to obtain a clear solution. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the above three-necked flask, and the reaction temperature was controlled at 300 °C. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of a mixed solution of 0.2 mmol / mL cadmium oleate and 0.1 mmol / mL S-ODE into the three-necked flask. React for another 5 minutes, then cool to 250°C and inject 1 mL of 0.2 mmol / mL cadmium oleate solution. Allow the mixture to warm to room temperature. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Next, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension and 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Finally, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating twice. React for 10 minutes, then immediately stop heating.
[0062] Weigh 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified ZnS / CdS / CdS / CdSeS / CdSe quantum dot solution with an absorbance of 50 at the first exciton absorption peak. Raise the temperature to 300 °C. Add 1 mL of a mixture of cadmium oleate and 1 mL of S-TBP at a rate of 5 mL / h, followed by 4 mL of S-TBP solution at a rate of 5 mL / h. After the addition is complete, cool down to stop the reaction, thus obtaining the desired quantum dots.
[0063] Example 5: Synthesis of ZnS / CdZnS / CdS / CdSeS / CdSe / CdS / CdZnS / ZnS core-shell quantum dots
[0064] Synthesis of ZnS / CdZnS / CdS / CdSeS / CdSe / CdS core-shell quantum dots: ZnO (0.016 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the temperature was raised to 300 °C to obtain a clear solution. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the above three-necked flask, and the reaction temperature was controlled at 300 °C. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of a mixed solution of 0.2 mmol / mL cadmium oleate and 0.1 mmol / mL S-ODE into the three-necked flask. React for another 5 minutes, then cool to 250°C and inject 1 mL of 0.2 mmol / mL cadmium oleate solution. Allow the mixture to warm to room temperature. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Next, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension and 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating twice. React for 10 minutes, then every 2–3 minutes, rapidly inject 0.1 mL of... Add 0.1 mmol / mL S-ODE solution, react for 10 minutes, and immediately stop heating.
[0065] Weigh 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified ZnS / CdS / CdS / CdSeS / CdSe / CdS quantum dot solution with an absorbance of 50 at the first exciton absorption peak. Raise the temperature to 300 °C. Add 1 mL of a mixture of cadmium oleate and 1 mL of S-TBP at a rate of 5 mL / h, followed by 4 mL of S-TBP solution at a rate of 5 mL / h. After the addition is complete, cool down to stop the reaction, thus obtaining the desired quantum dots.
[0066] Example 6: Synthesis of ZnS / ZnSeS / ZnSe / CdSe / CdZnS / ZnS core-shell quantum dots
[0067] Synthesis of ZnS / ZnSeS / ZnSe / CdSe core-shell quantum dots: ZnO (0.016 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the temperature was raised to 300 °C to obtain a clear solution. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the above three-necked flask, and the reaction temperature was controlled at 300 °C. After reacting for 5 minutes, every 2-3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL mixture of selenium powder-ODE and 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating 3 times. React for 5 minutes. Then, every 2-3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL Se powder-ODE solution into the three-necked flask, repeating 4 times. Then, inject 1 mL of a 0.2 mmol / mL cadmium oleate solution. Every 2-3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating 5 times. React for 10 minutes, then immediately stop heating.
[0068] Weigh 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified ZnS / ZnSeS / ZnSe / CdSe quantum dot solution with a first exciton absorption peak absorbance of 50. Raise the temperature to 300 °C. Add 1 mL of a mixture of cadmium oleate and 1 mL of S-TBP at a rate of 5 mL / h, followed by 4 mL of S-TBP solution at a rate of 5 mL / h. After the addition is complete, cool down to stop the reaction, thus obtaining the desired quantum dots.
[0069] Example 7 Synthesis of ZnS / ZnSeS / CdZnSe / ZnSe / CdSe / CdZnS / ZnS core-shell quantum dots
[0070] Synthesis of ZnS / ZnSeS / CdZnSe / ZnSe / CdSe core-shell quantum dots: ZnO (0.016 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the temperature was raised to 300 °C to obtain a clear solution. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the above three-necked flask, and the reaction temperature was controlled at 300 °C. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL mixture of selenium powder-ODE and 0.1 mL of a 0.1 mmol / mL S-ODE solution into the three-necked flask, repeating this process 3 times. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL mixture of Se powder-ODE and 0.1 mL of a 0.2 mmol / mL cadmium oleate solution into the three-necked flask, repeating this process twice. Then, rapidly inject 0.1 mL of a 0.1 mmol / mL Se powder-ODE solution into the three-necked flask, repeating this process twice. Next, inject 1 mL of a 0.2 mmol / mL cadmium oleate solution. Every 2–3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating this process 5 times. After reacting for 10 minutes, immediately stop heating.
[0071] Weigh 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified ZnS / ZnSeS / CdZnSe / ZnSe / CdSe quantum dot solution with a first exciton absorption peak absorbance of 50. Raise the temperature to 300 °C. Add 1 mL of a mixture of cadmium oleate and 1 mL of S-TBP at a rate of 5 mL / h, followed by 4 mL of S-TBP solution at a rate of 5 mL / h. After the addition is complete, cool down to stop the reaction, thus obtaining the desired quantum dots.
[0072] Example 8: Synthesis of ZnS / ZnSeS / ZnSe / CdZnSe / CdSe / CdZnSe / CdZnS / ZnS core-shell quantum dots
[0073] Synthesis of ZnS / ZnSeS / ZnSe / CdZnSe / CdSe core-shell quantum dots: ZnO (0.016 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the temperature was raised to 300 °C to obtain a clear solution. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the above three-necked flask, and the reaction temperature was controlled at 300 °C. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL mixture of selenium powder-ODE and 0.1 mL of a 0.1 mmol / mL S-ODE solution into the three-necked flask, repeating 3 times. React for 5 minutes. Then, every 2–3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL Se powder-ODE solution into the three-necked flask, repeating 2 times. Then, rapidly inject 0.1 mL of a 0.1 mmol / mL mixture of Se powder-ODE and 0.1 mL of a 0.2 mmol / mL cadmium oleate solution into the three-necked flask, repeating 2 times. Then, inject 1 mL of a 0.2 mmol / mL cadmium oleate solution. Every 2–3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating 5 times. React for 10 minutes, then immediately stop heating.
[0074] Weigh 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified ZnS / ZnSeS / ZnSe / CdZnSe / CdSe quantum dot solution with an absorbance of 50 at the first exciton absorption peak. Raise the temperature to 300 °C. Add 0.5 mL of a mixture of cadmium oleate and 1 mL of Se-TBP at a rate of 5 mL / h, followed by 1 mL of a mixture of cadmium oleate and 1 mL of S-TBP at a rate of 5 mL / h, and then 3 mL of S-TBP solution at a rate of 10 mL / h. After the addition is complete, cool down to stop the reaction, thus obtaining the desired quantum dots.
[0075] Example 9: Synthesis of ZnS / ZnSeS / ZnSe / CdZnSe / CdSe / CdZnSe / ZnSe / CdZnS / ZnS core-shell quantum dots
[0076] Synthesis of ZnS / ZnSeS / ZnSe / CdZnSe / CdSe core-shell quantum dots: ZnO (0.016 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the temperature was raised to 300 °C to obtain a clear solution. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the above three-necked flask, and the reaction temperature was controlled at 300 °C. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL mixture of selenium powder-ODE and 0.1 mL of a 0.1 mmol / mL S-ODE solution into the three-necked flask, repeating 3 times. React for 5 minutes. Then, every 2–3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL Se powder-ODE solution into the three-necked flask, repeating 2 times. Then, rapidly inject 0.1 mL of a 0.1 mmol / mL mixture of Se powder-ODE and 0.1 mL of a 0.2 mmol / mL cadmium oleate solution into the three-necked flask, repeating 2 times. Then, inject 1 mL of a 0.2 mmol / mL cadmium oleate solution. Every 2–3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating 5 times. React for 10 minutes, then immediately stop heating.
[0077] Weigh 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified ZnS / ZnSeS / ZnSe / CdZnSe / CdSe quantum dot solution with an absorbance of 50 at the first exciton absorption peak. Raise the temperature to 300 °C. Add 0.5 mL of a mixture of cadmium oleate and 1 mL of Se-TBP at a rate of 5 mL / h, followed by 1 mL of a Se-TBP mixture at a rate of 5 mL / h, then 1 mL of a cadmium oleate and 1 mL of S-TBP mixture at a rate of 5 mL / h, and finally 2 mL of S-TBP solution at a rate of 10 mL / h. After the addition is complete, cool down to stop the reaction, yielding the desired quantum dots.
[0078] Example 10 Synthesis of ZnS / ZnSeS / ZnSe / CdZnSe / CdSe / CdZnSe / ZnSe / ZnSeS / ZnS core-shell quantum dots
[0079] Synthesis of ZnS / ZnSeS / ZnSe / CdZnSe / CdSe core-shell quantum dots: ZnO (0.016 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the temperature was raised to 300 °C to obtain a clear solution. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the above three-necked flask, and the reaction temperature was controlled at 300 °C. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL mixture of selenium powder-ODE and 0.1 mL of a 0.1 mmol / mL S-ODE solution into the three-necked flask, repeating 3 times. React for 5 minutes. Then, every 2–3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL Se powder-ODE solution into the three-necked flask, repeating 2 times. Then, rapidly inject 0.1 mL of a 0.1 mmol / mL mixture of Se powder-ODE and 0.1 mL of a 0.2 mmol / mL cadmium oleate solution into the three-necked flask, repeating 2 times. Then, inject 1 mL of a 0.2 mmol / mL cadmium oleate solution. Every 2–3 minutes, rapidly inject 0.1 mL of a 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating 5 times. React for 10 minutes, then immediately stop heating.
[0080] Weigh 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified ZnS / ZnSeS / ZnSe / CdZnSe / CdSe quantum dot solution with an absorbance of 50 at the first exciton absorption peak. Raise the temperature to 300 °C. Add 0.5 mL of a mixture of cadmium oleate and 1 mL of Se-TBP at a rate of 5 mL / h, followed by 1 mL of a Se-TBP mixture at a rate of 5 mL / h. Then add 1 mL of a Se-TBP and 1 mL of S-TBP mixture at a rate of 5 mL / h, followed by 1 mL of S-TBP solution at a rate of 10 mL / h. After the addition is complete, cool down to stop the reaction, yielding the desired quantum dots.
[0081] Example 11 Synthesis of ZnS / CdZnS / CdS / CdSeS / CdSe / CdSeS / CdS / CdZnS / ZnS core-shell quantum dots
[0082] Synthesis of ZnS / CdZnS / CdS / CdSeS / CdSe / CdSeS / CdS quantum dots: ZnO (0.016 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the temperature was raised to 300 °C to obtain a clear solution. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the above three-necked flask, and the reaction temperature was controlled at 300 °C. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of a mixed solution of 0.2 mmol / mL cadmium oleate and 0.1 mmol / mL S-ODE into the three-necked flask. React for another 5 minutes, then cool to 250°C and inject 2 mL of 0.2 mmol / mL cadmium oleate solution. Allow the mixture to warm to room temperature. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Next, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension and 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating twice. React for 10 minutes, then every 2–3 minutes, rapidly inject 0.1 mL of... Add 0.1 mmol / mL selenium powder suspension and 0.2 mL of 0.1 mmol / mL S-ODE, repeating twice. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Immediately stop heating.
[0083] Weigh 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified ZnS / CdS / CdSeS / CdSe / CdSeS / CdS quantum dot solution with a first exciton absorption peak absorbance of 50. Raise the temperature to 300 °C. Add 1 mL of a mixture of cadmium oleate and 1 mL of S-TBP at a rate of 5 mL / h, followed by 4 mL of S-TBP solution at a rate of 5 mL / h. After the addition is complete, cool down to stop the reaction, thus obtaining the desired quantum dots.
[0084] Example 12 Synthesis of CdS / CdSeS / CdSeS / CdSeS / CdSe / CdS core-shell quantum dots:
[0085] Synthesis of CdS / CdSeS / CdSeS / CdSeS / CdSe quantum dots: CdO (0.0256 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the mixture was heated to 280 °C to obtain a clear solution, which was then cooled to 250 °C. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the three-necked flask, and the reaction temperature was maintained at 250 °C. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of 0.05 mmol / mL selenium powder suspension and 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Then, every 2–3 minutes, inject 1 mL of 0.2 mmol / mL cadmium oleate solution. After warming, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension and 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension and 0.1 mL of 0.05 mmol / mL S-ODE into the three-necked flask, repeating twice. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension into the three-necked flask, repeating twice. React for 10 minutes, then immediately stop heating.
[0086] Weigh 5 mmol of cadmium oxide, 5.6 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified CdS / CdSeS / CdSeS / CdSeS / CdSe quantum dot solution with an absorbance of 50 at the first exciton absorption peak. Raise the temperature to 250 °C. Add 2.5 mL of S-TBP solution at a rate of 5 mL / h. After the addition is complete, cool down to stop the reaction, thus obtaining the desired quantum dots.
[0087] Example 13 Synthesis of ZnS / CdZnS / CdS / CdSeS / CdSeS / CdS / CdZnS / ZnS core-shell quantum dots
[0088] Synthesis of ZnS / CdZnS / CdS / CdSeS / CdSeS / CdS quantum dots: ZnO (0.016 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the temperature was raised to 300 °C to obtain a clear solution. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the above three-necked flask, and the reaction temperature was controlled at 300 °C. After reacting for 5 minutes, every 2–3 minutes, rapidly inject 0.1 mL of a mixed solution of 0.2 mmol / mL cadmium oleate and 0.1 mmol / mL S-ODE into the three-necked flask. React for another 5 minutes, then cool to 250°C and inject 2 mL of 0.2 mmol / mL cadmium oleate solution. Allow the mixture to warm to room temperature. Then, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Next, every 2–3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL selenium powder suspension and 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask, repeating twice. Finally, every 2–3 minutes, rapidly inject 0.2 mL of 0.2 mmol / mL selenium powder suspension and 0.1 mL of S-ODE into the three-necked flask. Add 0.1 mmol / mL S-ODE twice. Then, every 2 to 3 minutes, rapidly inject 0.1 mL of 0.1 mmol / mL S-ODE into the three-necked flask twice. Stop heating immediately afterward.
[0089] Weigh 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified ZnS / CdS / CdSeS / CdSeS / CdS quantum dot solution with an absorbance of 50 at the first exciton absorption peak. Raise the temperature to 300 °C. Add 1 mL of a mixture of cadmium oleate and 1 mL of S-TBP at a rate of 5 mL / h, followed by 4 mL of S-TBP solution at a rate of 5 mL / h. After the addition is complete, cool down to stop the reaction, thus obtaining the desired quantum dots.
[0090] Comparative Example 1: Synthesis of CdS / CdSe / CdS core-shell quantum dots:
[0091] Synthesis of CdS / CdSe quantum dots: CdO (0.0256 g, 0.2 mmol), HSt (stearic acid, 0.1420 g, 0.5 mmol), and ODE (octadecene, 4 mL) were placed in a 25 mL three-necked flask. After stirring and purging with argon gas for 10 minutes, the mixture was heated to 280 °C to obtain a clear solution, which was then cooled to 250 °C. 1 mL of 0.1 mmol / mL S-ODE was rapidly injected into the three-necked flask, and the reaction temperature was maintained at 250 °C. After 5 minutes of reaction, 1 mL of 0.2 mmol / mL cadmium oleate solution was injected, and the mixture was allowed to cool. Subsequently, every 2–3 minutes, 0.2 mL of 0.1 mmol / mL selenium powder suspension was rapidly injected into the three-necked flask, repeating this process 6 times. The reaction was carried out for 10 minutes, after which heating was immediately stopped.
[0092] Weigh 5 mmol of cadmium oxide, 5.6 g of oleic acid, and 20 mL of ODE into a 100 mL three-necked flask. At 200 °C, purge with inert gas for 30 minutes. Inject a purified CdS / CdSe quantum dot solution with an absorbance of 50 at the first exciton absorption peak. Raise the temperature to 250 °C. Add 2.5 mL of S-TBP solution at a rate of 5 mL / h. After the addition is complete, cool down to stop the reaction, thus obtaining the desired quantum dots.
[0093] Synthesis of Comparative Example 2: CdSe / CdZnS / ZnS core-shell quantum dots: 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL LODE were weighed into a 100 mL three-necked flask. The mixture was purged with an inert gas for 30 minutes at 200 °C. A purified CdSe quantum dot solution with an absorbance of 50 at the first exciton absorption peak (UV peak position consistent with the first step in Example 1) was then injected. The temperature was raised to 300 °C. A mixture of 1 mL of cadmium oleate and 1 mL of S-TBP was added at a rate of 5 mL / h, followed by the dropwise addition of 4 mL of S-TBP solution at a rate of 5 mL / h. After the addition was complete, the temperature was lowered to stop the reaction, yielding the desired quantum dots.
[0094] Synthesis of Comparative Example 3: CdSeS / CdS / CdZnS / ZnS core-shell quantum dots: 10 mmol of zinc acetate, 11.2 g of oleic acid, and 20 mL of ODE were weighed into a 100 mL three-necked flask. The mixture was purged with an inert gas for 30 minutes at 200 °C. A purified CdSeS / CdS quantum dot solution with an absorbance of 50 at the first exciton absorption peak (UV peak position consistent with the first step in Example 13) was then injected. The temperature was raised to 300 °C. A mixture of 1 mL of cadmium oleate and 1 mL of S-TBP was added at a rate of 5 mL / h, followed by the dropwise addition of 4 mL of S-TBP solution at a rate of 5 mL / h. After the addition was complete, the temperature was lowered to stop the reaction, yielding the desired quantum dots.
[0095] The parameters of the quantum dots in Examples 1-13 and the comparative examples are shown in Table 1.
[0096]
[0097] Example 12 and Comparative Example 1 were obtained by aging the toluene solution (prepared to have an absorbance of 4 at 450 nm) under 20 mW light for 5 hours. Figure 3 The photos show Example 12 on the left and a comparative example on the right. It can be seen that the quantum dot toluene solution on the left is more efficient.
[0098] Verification Example
[0099] The quantum dots from Examples 1 and 13, and the quantum dots from Comparative Examples 2 and 3, were used in quantum dot polystyrene diffusion plates (multi-layer high-temperature co-extrusion integral molding, with the quantum dot layer in the middle, and the same formulation). The quantum dot diffusion plates were then aged for 0-480 hours under conditions of 80°C, 80% humidity, and 20mW light. The results for the quantum dot diffusion plates corresponding to Examples 1 and 13 are shown in [reference 1]. Figure 4 and Figure 5 For the results of quantum dot diffusion plates corresponding to Comparative Examples 2 and 3, please refer to [link / reference]. Figure 6 and Figure 7 As can be seen, under the above aging conditions, unlike the quantum dots in the comparative example, the fluorescence emission spectrum of the quantum dot diffuser plate in the embodiment remains basically unchanged. Under the same conditions, this demonstrates that the quantum dots in the embodiment have excellent light stability.
[0100] While specific embodiments of this disclosure have been described in detail by way of example, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. The various embodiments disclosed herein can be combined in any way without departing from the spirit and scope of this disclosure. Those skilled in the art should also understand that various modifications can be made to the embodiments without departing from the scope and spirit of this disclosure. The scope of this disclosure is defined by the appended claims.
Claims
1. A core-shell quantum dot, characterized in that, The core-shell quantum dot comprises, from the inside out, a quantum dot core, N shells, a light-emitting shell, and M shells, where N is an integer greater than or equal to 3 and M is an integer greater than or equal to 2. The light-emitting shell has the smallest band width. The valence bands of the N shells gradually increase away from the quantum dot core, and the conduction bands of the N shells gradually decrease away from the quantum dot core. The conduction band of the Nth shell is lower than the conduction band corresponding to the smallest band width among the M shells, and the valence band of the Nth shell is higher than the valence band corresponding to the smallest band width among the M shells.
2. The core-shell quantum dot according to claim 1, characterized in that, The size of the core-shell quantum dot is larger than the Bohr exciton diameter of the luminescent shell; preferably, the thickness of the N shells is independently selected from 0.5-3 nm.
3. The core-shell quantum dot according to claim 1, characterized in that, The band widths of the M shells gradually increase along the direction away from the quantum dot core.
4. The core-shell quantum dot according to claim 1, characterized in that, The core-shell quantum dots include cadmium, zinc, sulfur, and selenium; optionally, the core-shell quantum dots also include tellurium; optionally, each of the N shells contains three elements or each contains four elements.
5. The core-shell quantum dot according to claim 4, characterized in that, The core-shell quantum dots are CdS / CdSeS / CdSeS / CdSeS / CdSe / CdZnS / ZnS, CdS / CdSeS / CdSeS / CdSeS / CdSe / CdS / CdZnS / ZnS, Zn S / CdZnS / CdS / CdSe / CdZnS / ZnS, ZnS / CdZnS / CdS / CdSeS / CdSe / CdZnS / ZnS, ZnS / CdZnS / CdS / CdSeS / CdSe / C dS / CdZnS / ZnS, CdS / CdSeS / CdSeS / CdSeS / CdSe / CdS / CdZnS / ZnS, ZnS / ZnSeS / CdZnSe / ZnSe / CdSe / CdZnS / Z nS、ZnS / ZnSeS / ZnSe / CdZnSe / CdSe / CdZnSe / CdZnS / ZnS、ZnS / ZnSeS / ZnSe / CdZnSe / CdSe / CdZnSe / ZnSe / CdZ nS / ZnS, ZnS / ZnSeS / ZnSe / CdZnSe / CdSe / CdZnSe / ZnSe / ZnSeS / ZnS, ZnS / CdZnS / CdS / CdSeS / CdSe / CdSeS / C dS / CdZnS / ZnS, CdS / CdSeS / CdSeS / CdSeS / CdSe / CdS, ZnS / CdZnS / CdS / CdSeS / CdSeS / CdS / CdZnS / ZnS, ZnS / ZnSeS / ZnSe / CdSe / CdZnS / ZnSZnS / CdS / CdSeS / CdSe / CdS / CdZnS / ZnS、ZnS / ZnSeS / ZnSe / CdZnSe / CdTe / CdZ nS / ZnS, ZnS / ZnSeS / ZnSe / CdZnSe / CdTe / ZnSeS / ZnS, or ZnS / ZnSeS / ZnSe / CdZnSe / CdTe / ZnSeS / CdZnS / ZnS.
6. The core-shell quantum dot according to claim 1, characterized in that, The N shells are composed of the same elements, but the element ratios of each shell are different; preferably, the sum of M and N is less than or equal to 10, more preferably, N is less than or equal to 6 and M is less than or equal to 4.
7. The core-shell quantum dot according to claim 1, characterized in that, The difference between the valence band energy level corresponding to the smallest band width among the N shells and the smallest band width among the M shells is less than 0.5 eV, and the difference between the conduction band energy level corresponding to the smallest band width among the N shells and the smallest band width among the M shells is less than 1.5 eV.
8. The core-shell quantum dot according to claim 1, characterized in that, The fluorescence half-width of the core-shell quantum dots is less than or equal to 35 nm, and the quantum yield of the core-shell quantum dots is greater than or equal to 75%.
9. A quantum dot composition comprising the core-shell quantum dot according to any one of claims 1-8.
10. A quantum dot photoluminescent device comprising the core-shell quantum dot as described in any one of claims 1-8.