A boron-containing quantum dot, a preparation method thereof, an optical member, and an electronic device

Abstract

The present application relates to the technical field of optical materials, and in particular to a boron-containing quantum dot, a preparation method thereof, an optical component and an electronic device. The boron-containing quantum dot comprises a core layer and a shell layer covering the core layer; at least one of the core layer and the shell layer comprises boron and a II-VI semiconductor compound. The boron is doped into at least one of the core layer and the shell layer in the form of interlattice doping, and in the core layer and / or the shell layer, the boron is connected to a non-metal element in the II-VI semiconductor compound by a chemical bond. The boron-containing quantum dot further comprises an adsorption layer on the surface of the shell layer, and the adsorption layer comprises boron. The II-VI semiconductor compound comprises at least one of a II-VI binary compound, a II-VI ternary compound and a II-VI quaternary compound. The present application can improve the thermal stability of quantum dot materials.

Description

Technical Field

[0001] This invention relates to the technical field of optical materials, specifically to a boron-containing quantum dot and its preparation method, optical components, and electronic devices. Background Technology

[0002] Quantum dot materials are nanoscale semiconductor materials with quantum confinement effects, exhibiting unique optoelectronic properties. Currently, based on chemical composition, quantum dot materials mainly include group II-VI quantum dots, group III-V quantum dots, perovskite quantum dots, and other novel quantum dots. Among them, group II-VI quantum dots are the most extensively studied and widely used quantum dot materials.

[0003] Taking group II-VI quantum dot materials as an example, their internal structure and surface properties often lead to thermal stability defects, significantly affecting their performance and lifespan at high temperatures. For instance, on the one hand, the internal stability of group II-VI quantum dot crystals relies on the electrostatic interaction of ionic bonds and the orbital hybridization of covalent bonds. However, these crystals have relatively low lattice energy and numerous interstitial sites within the unit cell. When thermally excited, the vibrational amplitude of atoms increases, easily leading to cation / anion displacement or vacancies, disrupting the long-range order of the crystal. On the other hand, due to the large specific surface area of ​​quantum dot materials, the coordination number of surface atoms is much lower than that of bulk atoms, resulting in numerous defects such as dangling bonds, surface vacancies, and unsaturated coordination sites. These defects exacerbate nonradiative recombination processes at high temperatures, leading to decreased luminescence efficiency and rapid material degradation. Therefore, these properties of quantum dot materials reduce their thermal stability, limiting their application in high-temperature environments.

[0004] Doping quantum dot materials with metallic or non-metallic elements is an effective way to control their optical, electrical, magnetic properties and thermal stability. Commonly, related technologies involve doping the inorganic structures of quantum dot materials such as InP, GaAs, and group II-VI CdSe and ZnS with metallic elements like Mn, Al, Zr, and Cu to regulate the optical properties and thermal stability of the quantum dot system. The effects vary greatly depending on the quantum dot structure, doping system, specific preparation method, and doping amount. Currently, the core challenge in elemental doping of quantum dots lies in precisely controlling the doping process. At the nanoscale, doped atoms may enter incorrect lattice positions or be repelled to the surface, thus failing to perform their intended function; or disordered and excessive doping may severely disrupt the main lattice structure, significantly reducing the original optical properties of the quantum dot material. Summary of the Invention

[0005] The present invention aims to improve the thermal stability of quantum dot materials.

[0006] To solve or partially solve the above problems, as a first aspect, the present invention provides a boron-containing quantum dot, the boron-containing quantum dot comprising a core layer and a shell layer covering the core layer; at least one of the core layer and the shell layer comprises boron and a group II-VI semiconductor compound, the boron is doped into at least one of the core layer and the shell layer in the form of interlattice doping, and in the core layer and / or the shell layer, the boron is connected to the non-metallic element in the group II-VI semiconductor compound by chemical bonds.

[0007] Optionally, the boron-containing quantum dot further includes an adsorption layer located on the surface of the shell, the adsorption layer comprising boron.

[0008] Optionally, the II-VI semiconductor compound includes at least one of II-VI binary compounds, II-VI ternary compounds, and II-VI quaternary compounds.

[0009] Optionally, the group II-VI binary compound includes at least one of CdS, CdSe, CdTe, CdO, ZnS, ZnSe, ZnTe, and ZnO; the group II-VI ternary compound includes at least one of CdSeS, CdZnSe, ZnCdS, and ZnSeS; and the group II-VI quaternary compound includes CdZnSeS.

[0010] Optionally, the diameter of the core layer ranges from 1 nm to 12 nm, and the thickness of the shell layer ranges from 2 nm to 5 nm.

[0011] Optionally, the boron content of the boron-containing quantum dots is 30 to 7500 ppm; and / or, when the core layer comprises boron and a group II-VI semiconductor compound, the boron content of the boron-containing quantum dots in the core layer is 10 to 1000 ppm; and / or, when the shell layer comprises boron and a group II-VI semiconductor compound, the boron content of the boron-containing quantum dots in the shell layer is 50 to 6000 ppm.

[0012] Optionally, the number of shells includes one or at least two layers. When the number of shells is two and the shells include boron and group II-VI semiconductor compounds, the boron is located in any one or more of the at least two shells.

[0013] As a second aspect, the present invention also provides a method for preparing boron-containing quantum dots, for preparing boron-containing quantum dots as described in the first aspect, the method for preparing boron-containing quantum dots comprising: sequentially preparing a core layer and a shell layer, and contacting a boron-containing precursor with a group II-VI semiconductor compound precursor during the nucleation and / or shell formation process to obtain the boron-containing quantum dots;

[0014] The boron-containing precursor is the compound corresponding to Formula I:

[0015] Formula I: ;

[0016] In Formula I, R1 and R2 are independently selected from hydrocarbon, substituted hydrocarbon, aryl, substituted aryl, alkoxy, hydroxyl and allyl, respectively. R3, R4 and R5 are independently selected from hydrocarbon, substituted hydrocarbon, aryl, substituted aryl, alkoxy, carboxyl, allyl and hydroxyl, respectively.

[0017] Optionally, during the nucleation and / or shell formation process, the boron-containing precursor is contacted with the group II-VI semiconductor compound precursor at a temperature of 250°C to 350°C to obtain the boron-containing quantum dots.

[0018] Optionally, after sequentially preparing the core layer and the shell layer, the method further includes: mixing the boron-containing quantum dots with a boron-containing compound to form an adsorption layer on the surface of the boron-containing quantum dots.

[0019] Optionally, the boron-containing precursor is obtained by reacting a boron-containing compound with a silicon-containing compound, wherein the boron-containing compound includes boron hydroxyl compounds and / or boron ester compounds, and the silicon-containing compound has silanoxy and / or silanol groups.

[0020] As a third aspect, the present invention also provides an optical component comprising boron-containing quantum dots as described in the first aspect, or boron-containing quantum dots prepared by the method for preparing boron-containing quantum dots as described in the second aspect.

[0021] As a fourth aspect, the present invention also provides an electronic device comprising boron-containing quantum dots as described in the first aspect, or boron-containing quantum dots prepared by the method for preparing boron-containing quantum dots as described in the second aspect.

[0022] The beneficial effects of this invention compared to related technologies include at least the following:

[0023] Compared to related technologies where boron exists only in chemical ligands on the surface of quantum dots, in the boron-containing quantum dots of this invention, boron can be located in the core and / or shell layers of group II-VI quantum dots. Introducing boron into the core and / or shell layers allows boron atoms to enter the interlayer space, leading to slight lattice dislocations and exhibiting lattice distortion caused by interlayer doping. A small amount of boron doping affects the band gap of the semiconductor, causing a red shift in the first exciton absorption peak and a blue shift in the fluorescence emission peak. This demonstrates that boron, through doping into the lattice, forms a new structure and possesses novel photoelectric properties. Furthermore, the boron element inside the quantum dot enhances the transport of charge carriers within the shell through empty orbitals to optimize optical properties. At the same time, boron atoms can also form stronger bonds with non-metallic elements through chemical bonds (such as covalent or coordinate bonds like B-Se, BS, BO, B-Te, etc.) to form more stable intra-layer or inter-layer lattice nodes. This reduces interlayer slip and improves lattice stability, resulting in stronger thermal stability and water and oxygen tolerance. These factors synergistically improve the optical properties and thermal stability of quantum dot materials. Under appropriate conditions, doping still maintains a fluorescence quantum yield of more than 80% for quantum dots.

[0024] Furthermore, the boron-containing quantum dots in this invention are prepared using boron-containing precursors that do not contain halogen compounds or hazardous boranes. The BO-Si chemical bonds in the boron-containing precursors possess a certain bond energy, thus the thermal stability of the boron-containing precursors is higher than that of the boron-containing compounds before bonding, which is beneficial for improving the utilization efficiency and safety of the boron-containing precursors under high-temperature (260℃ to 340℃) reaction conditions. Through the rational selection and proportioning of reactants, the number and type of various groups in the boron-containing precursors can be adjusted, giving it the characteristic of adjustable thermal decomposition temperature. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of boron-containing quantum dots in an exemplary embodiment of the present invention;

[0026] Figure 2 This is a graph showing the mass residual rate (residual weight rate) of octyltrimethoxysilane, phenylboronic acid, and the prepared boron-containing precursor as a function of temperature in an exemplary embodiment of the present invention.

[0027] Figure 3 This is a graph showing the first derivative of the mass residual rate (residual weight rate) of octyltrimethoxysilane, phenylboronic acid, and the prepared boron-containing precursor as a function of temperature in an exemplary embodiment of the present invention.

[0028] Figure 4 This is a TEM characterization image of boron-containing quantum dots in an exemplary embodiment of the present invention;

[0029] Figure 5 This is a TEM image of a boron-containing quantum dot before boron element is doped into the internal lattice of the quantum dot in an exemplary embodiment of the present invention;

[0030] Figure 6 This is a TEM image of a boron-containing quantum dot after its internal lattice has been doped with boron in an exemplary embodiment of the present invention.

[0031] Figure 7 The graphs show the fluorescence quantum efficiency changes of the quantum dot samples of Example 3-c and Control Example 3 at different temperatures (normalized with the initial fluorescence quantum efficiency at 50℃ as 100%).

[0032] Figure 8 The fluorescence emission spectra of quantum dot samples from Example 3-c and Control Example 3 at different temperatures are shown.

[0033] Figure 9 The UV-Vis absorption spectra of the quantum dot samples of Example 3-c and Control Example 3 are shown (with the first exciton absorption peak normalized).

[0034] Explanation of reference numerals in the attached figures: 1. Core; 2. Shell; 21. First shell; 22. Second shell; 3. Boron. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0036] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit this application.

[0037] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the description below. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0038] II-VI group semiconductor compound materials (such as CdSe, CdS, ZnSe, ZnS, etc.) are the most widely used quantum dot systems. Their thermal stability is mainly limited by the high atomic mobility caused by high surface energy, as well as the desorption / oxidation of organic ligands, increased surface defects, and non-radiative recombination at high temperatures, ultimately leading to luminescence quenching and performance degradation. Related technologies typically employ methods such as constructing core-shell structures and physical encapsulation to improve the thermal stability or optical properties of quantum dot systems. For example, coating a CdSe core with a higher bandgap ZnSe, CdS, or ZnS shell, or encapsulating the core with a higher bond energy wide bandgap material (ZnS), can passivate the surface and form a physical barrier, which is one of the most effective means to improve stability, while also effectively improving the luminescence efficiency of quantum dots. Another example is embedding quantum dots into solid matrices such as glass, polymers, or silicon dioxide for physical encapsulation to isolate oxygen and limit their movement and ripening.

[0039] Some related technologies, such as Chinese patents and their families with publication numbers CN118546671A, CN114686205A, and CN113634240A, disclose the use of boron-containing compounds of various structures as ligands to modify the surface of quantum dots through chemical bonding, thereby improving the antioxidant properties of quantum dot materials or optimizing surface carrier transport. However, the effect of boron attached to the surface of quantum dot materials on improving the various properties of quantum dots is very limited.

[0040] Doping quantum dot materials with metallic or non-metallic elements is an effective means of controlling their optical, electrical, and magnetic properties. Commonly, related technologies, such as Chinese patents and their families with publication numbers CN103450904A, CN109337689A, and CN111909698A, involve doping metallic elements such as Mn, Al, Zr, and Cu into the inorganic structures of quantum dot materials like InP, GaAs, and group II-VI CdSe and ZnS to control the optical properties of the quantum dot system. The effects vary greatly depending on the quantum dot structure, doping system, specific preparation method, and doping amount. Currently, the core challenge in elemental doping of quantum dots lies in how to precisely control the doping process. At the nanoscale, doped atoms may enter incorrect lattice positions or be repelled to the surface, thus failing to perform their intended function; or disordered and excessive doping may severely damage the main lattice structure, significantly reducing the original optical properties of the quantum dot material.

[0041] To improve the doping efficiency of elements within crystals, some related technologies disclose the use of boron halides, alkyl borons, or boranes as boron sources for doping group III-V quantum dot materials such as InP. A key feature of these technologies is the use of small-molecule, low-boiling-point boron compounds, such as boron trifluoride. 、Triethylboron is synthesized at high temperatures (280°C) by introducing a boron source, which is then induced to decompose and release boron atoms into the quantum dot material. This process aims to suppress side reactions during quantum dot synthesis, passivate shell defects, and improve quantum yield. It should be noted that sufficient boron doping within the quantum dot structure depends on a high-temperature environment. High temperatures promote rapid decomposition of the boron source and simultaneously drive the complete growth of the quantum dot lattice, providing sufficient kinetic energy for boron atoms to overcome the lattice barrier and achieve uniform doping. However, due to the low boiling point of some boron sources, at reaction temperatures of 280°C or higher, these low-boiling-point boron sources are prone to vaporization or decomposition at extremely rapid rates at a specific temperature. This results in insufficient time for individual boron atoms to diffuse in bulk and find suitable lattice vacancies or substitution sites, increasing the risk of boron agglomeration or the formation of a second phase (such as metal borides) due to local supersaturation. This significantly reduces the doping efficiency and uniformity of boron, leading to localized stress concentration and uneven defect density in the crystal structure, which adversely affects the thermal stability and optical properties of the quantum dot material. Therefore, based on these objective problems, it is currently difficult to effectively control the doping morphology of boron in group III-V or group II-VI quantum dots, which limits the industrial application of boron doping technology in group III-V quantum dots.

[0042] Based on the above background, as a first aspect, embodiments of the present invention provide a boron-containing quantum dot, including a core layer 1 and a shell layer 2 covering the core layer 1; at least one of the core layer 1 and the shell layer 2 includes boron 3 and a group II-VI semiconductor compound, wherein boron 3 is doped into at least one of the core layer 1 and the shell layer 2 in the form of interlattice doping, and in the core layer 1 and / or the shell layer 2, boron 3 is connected to the non-metallic elements in the group II-VI semiconductor compound by chemical bonds.

[0043] It should be noted that the boron-containing quantum dots in the embodiments of the present invention have a core-shell structure, which has stronger thermal stability compared to a single-core structure. Furthermore, at least a portion of the boron-containing quantum dots in this core-shell structure contain a group II-VI semiconductor compound, and boron is doped into the group II-VI semiconductor compound. It can be understood that in some embodiments, both the core layer 1 and the shell layer 2 of the boron-containing quantum dots respectively contain a group II-VI semiconductor compound and boron 3; while in other optional embodiments, the group II-VI semiconductor compound and boron may only exist in the core layer 1 or the shell layer 2, and the composition of the corresponding shell layer 2 or core layer 1 is not limited, and may be any one or more of group III-V quantum dots (such as AlN, GaAs, InP), perovskite quantum dots, and other novel quantum dots.

[0044] In some alternative embodiments, the II-VI semiconductor compound includes at least one of II-VI binary compounds, II-VI ternary compounds, and II-VI quaternary compounds. For example, the II-VI binary compound may include at least one of CdS, CdSe, CdTe, CdO, ZnS, ZnSe, ZnTe, and ZnO; the II-VI ternary compound may include at least one of CdSeS, CdZnSe, ZnCdS, and ZnSeS; and the II-VI quaternary compound may include CdZnSeS.

[0045] Compared to related technologies where boron exists only as a chemical ligand on the surface of quantum dots, in the boron-containing quantum dots of this invention, boron 3 can be located in the core layer 1 and / or shell layer 2. After introducing boron into the core layer 1 and / or shell layer 2, boron atoms can enter the interlayer and dopantize at least one of the core layer 1 and shell layer 2 in the form of interlayer doping, leading to slight lattice dislocation and exhibiting lattice distortion caused by interlayer doping. Furthermore, within the quantum dot structure, boron atoms can interact with electrons through empty orbitals, making it more difficult for electrons to be taken away by oxidants. This enhances the stability of non-metallic elements in the core and shell structures as "electron donors," preventing changes in the valence state of the inorganic structure of the quantum dot and improving the performance of the quantum dot material. Simultaneously, empty orbitals can improve the transport of charge carriers within the shell to optimize optical properties. In addition, for the elements in group II-VI semiconductor compounds and boron, a comparison is made based on the size of their ionic radii. 3+ (27pm) < Zn 2+ (74pm) < Cd 2+ (78pm) <S 2- (170pm) <Se 2- (184 pm), while comparing covalent radii, B (82 pm) < S (105 pm) < Se (116 pm) < Zn (122 pm) < Cd (138 pm). Therefore, small-radius boron atoms or ions can be alloyed into the quantum dot lattice and further bond strongly with surrounding Group II / VI nonmetallic elements (O, S, Se, Te) through chemical bonds (such as covalent or coordinate bonds like B-Se, BS, BO, B-Te), forming more stable intralayer or interlayer lattice nodes. This reduces interlayer slip, improves lattice stability, and ultimately enhances the thermal stability of quantum dot materials.

[0046] In summary, the boron element inside the quantum dot of this invention enhances carrier transport within shell 2 through empty orbitals to optimize optical properties. Furthermore, it can form stable intralayer or translayer lattice nodes through lattice doping of boron atoms and chemical bonding with Group II / VI elements, thereby reducing interlayer slip and improving lattice stability. This results in stronger thermal stability and water / oxygen resistance. Consequently, the optical properties and thermal stability of the quantum dot material are synergistically improved, effectively suppressing the thermal quenching phenomenon of quantum dots. With appropriate doping levels, the fluorescence quantum yield of the quantum dots is greater than 80%.

[0047] In some optional embodiments, the diameter of the boron-containing quantum dot core layer 1 ranges from 1 nm to 12 nm, the thickness of the shell layer 2 ranges from 2 nm to 5 nm, and the emission wavelength of the boron-containing quantum dots is between 450 nm and 700 nm.

[0048] In some optional embodiments, the boron-containing quantum dots further include an adsorption layer on the surface of the shell 2, the adsorption layer comprising boron.

[0049] It should be noted that, based on the introduction of boron into the core layer 1 and / or shell layer 2, boron can also be bonded to the surface of the quantum dots in the form of chemical ligands to form an adsorption layer, thereby achieving surface modification of the quantum dots. For example, this can be achieved by chemically bonding boron-containing compounds to quantum dots to form tri-coordinate boron-containing quantum dot complexes and tetra-coordinate boron-containing quantum dot complexes. This part of the technology has been disclosed as prior art in patent publications such as CN118546671A, CN114686205A, and CN113634240A, and will not be elaborated here. It is understood that, because boron is further doped into the quantum dots to form stable intra- or inter-layer lattice nodes, the adsorption layer on the surface of shell layer 2 can bind to the anions on the quantum dot surface to form a more stable protection, resulting in superior overall heat resistance and stability of the boron-containing quantum dots.

[0050] In some optional embodiments, the boron content of the boron-containing quantum dots is 30 to 7500 ppm; when the core layer 1 includes boron and a group II-VI semiconductor compound, the boron content of the boron-containing quantum dots in the core layer 1 is 10 to 1000 ppm; when the shell layer 2 includes boron and a group II-VI semiconductor compound, the boron content of the boron-containing quantum dots in the shell layer 2 is 50 to 6000 ppm; and when the surface of the boron-containing quantum dots has an adsorption layer, the boron content of the boron-containing quantum dots in the adsorption layer is 5 to 500 ppm.

[0051] The above content values ​​can be understood as follows: taking the total mass of boron-containing quantum dots as 100%, the mass concentrations of core layer 1, shell layer 2, and adsorption layer, as well as the mass concentrations of all boron elements. It should be noted that the boron content in core layer 1 and the content of all boron elements relative to the total mass of boron-containing quantum dots can be obtained separately through ICP-OES testing. For boron-containing quantum dots where both core layer 1 and shell layer 2 contain boron, after the preparation of core layer 1, the mass and boron content of core layer 1 before coating can be tested first, followed by the mass and boron content of the quantum dots after coating. Subtracting the boron content before coating from the boron content after coating yields the boron content in shell layer 2. Furthermore, the boron content in the adsorption layer on the quantum dot surface can be obtained by calculating the difference between the total boron content and the purified content after thorough purification of the boron-containing quantum dots to remove the surface adsorption layer. The boron content in each layer relative to the corresponding mass of each layer can be calculated separately based on the corresponding mass of each layer and the mass of boron-containing quantum dots.

[0052] It should be noted that for boron-containing quantum dots with an adsorption layer on their surface, octane can be used as a solvent and ethanol as a precipitant. These can be mixed with the boron-containing quantum dots to remove the adsorption layer through a dissolution-precipitation purification method. A specific purification process may include: dispersing the boron-containing quantum dots in octane solvent until fully dissolved, then adding ethanol as a precipitant, mixing thoroughly, and centrifuging to discard the solution to obtain the quantum dot material precipitate. It can be understood that for boron-containing quantum dots with boron in the core / shell layer, purifying them 3 / 7 / 11 times respectively, and using ICP-OES to determine the elemental content of Zn, Cd, Se, S, and B in the boron-containing quantum dots after each purification round, it can be found that as the number of purification rounds increases, the boron content in the boron-containing quantum dots decreases and gradually stabilizes. This indicates that the boron bound solely to the adsorption layer on the surface of the boron-containing quantum dots through adsorption is removed after purification.

[0053] It is understandable that excessive doping can damage the main lattice structure and cause optical property degradation. By controlling the boron content of each layer within a certain range, the thermal stability of the quantum dot lattice can be significantly improved, and the impact on the optical properties of the quantum dot can be controlled at a low level, thereby achieving a comprehensive balance between its luminescence performance and thermal stability.

[0054] In some alternative embodiments, the number of shells 2 includes one or at least two layers. When the number of shells 2 is two and the shells 2 include boron and a group II-VI semiconductor compound, the boron is located in any one or more of the at least two shells 2.

[0055] It is understood that in the boron-containing quantum dots of this invention, the number of shell layers 2 outside the core layer 1 can be one or more, and the composition of the multiple shell layers 2 does not need to be the same. Boron can be located in any one or several of the shell layers 2. In an exemplary embodiment, the number of shell layers 2 is two. The core layer 1 of the boron-containing quantum dot is composed of CdSeS, and the shell layers 2 are CdS and ZnS in order from the inside to the outside, with boron located in the ZnS shell layer. Figure 1 As shown, Figure 1 This is an exemplary schematic diagram of a boron-containing quantum dot structure, wherein the shell 2 includes a first shell 21 and a second shell 22 distributed sequentially from the inside to the outside, and boron 3 is located simultaneously on the core layer 11, the first shell 21, the second shell 22 and the surface of the second shell 22.

[0056] As a second aspect, another embodiment of the present invention provides a method for preparing boron-containing quantum dots, used to prepare the boron-containing quantum dots as described above. The method for preparing boron-containing quantum dots includes: sequentially preparing a core layer 1 and a shell layer 2, and contacting a boron-containing precursor with a group II-VI semiconductor compound precursor during the nucleation and / or shell formation process to obtain boron-containing quantum dots;

[0057] The boron-containing precursor is the compound corresponding to Formula I:

[0058] Formula I: ;

[0059] In Formula I, R1 and R2 are independently selected from hydrocarbon, substituted hydrocarbon, aryl, substituted aryl, alkoxy, hydroxyl and allyl, respectively. R3, R4 and R5 are independently selected from hydrocarbon, substituted hydrocarbon, aryl, substituted aryl, alkoxy, carboxyl, allyl and hydroxyl, respectively.

[0060] It should be noted that the precursors of group II-VI semiconductor compounds include Zn precursors, Cd precursors, Se precursors, Te precursors, and S precursors. Zn precursors may include at least one of zinc acetate, zinc stearate, zinc oleate, zinc acetylacetonate, zinc carbonate, basic zinc carbonate, zinc nitrate, zinc oxide, and zinc sulfate; Cd precursors may include at least one of cadmium acetate, cadmium stearate, cadmium oleate, cadmium acetylacetonate, cadmium carbonate, basic cadmium carbonate, cadmium nitrate, cadmium oxide, and cadmium sulfate; Se precursors may include at least one of elemental selenium, trioctylphosphine-selenium (TOP-Se), tributylphosphine-selenium (TBP-Se), and triphenylphosphine-selenium (TPP-Se). The Te precursor includes at least one of TOP-Te (trioctylphosphine-tellurium complex) and TBP-Te (tributylphosphine-tellurium complex), and the S precursor may include at least one of elemental sulfur, hexamethylenetetramine, octylthiol, decanethiol, dodecanethiol, hexadecanethiol, mercaptopropylsilane, trioctylphosphine-sulfur (TOP-S), tributylphosphine-sulfur (TBP-S), triphenylphosphine-sulfur (TPP-S), trioctylamine-sulfur (TOA-S), hexamethyldisiloxane, ammonium sulfide, and sodium sulfide.

[0061] Furthermore, during the nucleation and / or shell formation process, the boron-containing precursor is contacted with the group II-VI semiconductor compound precursor at a temperature of 250°C to 350°C. The key to preparing quantum dots using the hot-injection method lies in the rapid injection of a highly reactive anionic precursor (such as S precursor, Se precursor, Te precursor) into a mixture of a hot cationic precursor (such as Zn precursor, Cd precursor), ligand, and solvent. It should be noted that in this embodiment of the invention, the boron-containing precursor should be added to the hot cationic precursor solution first, followed by the anionic precursor, and finally the temperature should be lowered to introduce the boron-containing precursor during the nucleation or shell formation process.

[0062] In some optional embodiments, the boron-containing precursor is obtained by reacting a boron-containing compound with a silane compound, wherein the molar ratio of the boron-containing compound to the silane is 1:(1.2 to 2.0). It is understood that since hot-injection polymerization is generally carried out at relatively high reaction temperatures, and some boron-containing compounds have boiling points below these reaction temperatures, such as triethylboron, borane, and boron trifluoride, directly using these low-boiling-point boron-containing compounds in the hot-injection reaction process results in easy vaporization, low utilization rate, and low safety, leading to uncontrolled and uneven doping of boron within the quantum dot structure. Therefore, it is necessary to further process the boron-containing compound to obtain a boron-containing precursor with a higher boiling point and thermal decomposition temperature.

[0063] In some optional embodiments, the boron-containing compounds include boron hydroxyl compounds and / or borate esters, and the silicon-containing compounds have silanoxy and / or silanol groups.

[0064] It should be noted that in the boron-containing compounds of the embodiments of the present invention, boron hydroxyl compounds are defined as boron-containing compounds containing a B-OH chemical bond in the molecule; boron ester compounds are defined as boron-containing compounds containing a B-OR bond (R is a C1-C12 alkyl or aryl group) in the molecule; wherein, based on safety considerations during use, halogenated boron compounds are excluded from the above-mentioned boron-containing compounds. As an example, the boron-containing compound may be selected from at least one of boric acid, phenylboronic acid, 4-methylphenylboronic acid, cyclopropylboronic acid, and triethyl borate. The silicon-containing compound may be selected from at least one of tetramethoxysilane, tetraethoxysilane, octyltrimethoxysilane, mercaptopropyltrimethoxysilane, aminopropyltrimethoxysilane, phenyltrimethoxysilane, trimethylsilanol, diphenylsilanediol, and orthosilicic acid (H4SiO4).

[0065] For example, taking phenylboronic acid and octyltrimethoxysilane as examples, the reaction formula for the synthesis of boron-containing precursors is as follows:

[0066]

[0067] The residual mass percentage (residual weight percentage) of octyltrimethoxysilane, phenylboronic acid, and the prepared boron-containing precursor, and their first derivative as a function of temperature, are shown in the following figures. Figure 2 and Figure 3 As shown in the figure, a comparison revealed that the boron-containing precursor exhibited a 50% mass residue at high temperatures (>300℃), and even at 600℃, it still retained a 10% mass residue. Compared to the weight loss peak temperatures obtained by first-order conduction for the two raw materials (150℃ for octyltrimethoxysilane and 300℃ for phenylboronic acid), the weight loss peak temperatures obtained by first-order conduction for the boron-containing precursor (first weight loss peak 200℃, second weight loss peak 500℃) also shifted towards the higher temperature range. This clearly indicates that the boron-containing precursor has superior thermal stability. Further analysis revealed that the first weight loss peak (200℃) of the boron-containing precursor is mainly composed of the superposition of weight loss peaks from the octyltrimethoxysilane and phenylboronic acid monomers (unreacted raw materials). The second weight loss peak (500℃) is generated by the partial removal of organic matter from the organic-inorganic hybrid macromolecule formed by the boron-containing compound and silane. Furthermore, the boron-containing precursor residue at 600℃, which accounts for approximately 10% of its mass, is mainly composed of inorganic substances formed by elements such as B, Si, and O.

[0068] from Figure 2 , Figure 3Further analysis reveals that the residual weight of phenylboronic acid decreases rapidly at 300℃, indicating a violent decomposition or vaporization. This suggests that when applied to quantum dot synthesis, the boron-containing precursor is extremely sensitive to the nucleation and growth temperatures and times of quantum dots. The reaction temperature of the quantum dots must be precisely aligned with this decomposition point, making it difficult to match the actual doping process window. In contrast, the boron-containing precursor undergoes a multi-step decomposition process, continuously and slowly releasing active boron over a wider temperature range. This low-concentration, continuous boron supply provides individual boron atoms with sufficient time for bulk diffusion, finding suitable lattice vacancies or substitution sites for incorporation. Simultaneously, it forms strong chemical bonds with non-metallic elements (O, S, Se, Te), significantly reducing the risk of boron agglomeration or the formation of second phases (such as metal borides) due to local supersaturation. Furthermore, because the release of boron spans a wider temperature range, its compatibility with the quantum dot growth / annealing process is higher, and minor fluctuations in process parameters (such as temperature and time) have a relatively smaller impact on the final doping result, effectively broadening the doping process window.

[0069] Further, optionally, an exemplary preparation process is provided for the synthesis of boron-containing precursors by reacting boron-containing compounds, such as any one or a combination of boric acid, phenylboronic acid, methylphenylboronic acid, and triethyl borate, with octyltrimethoxysilane and / or tetraethoxysilane:

[0070] 4g of phenylboronic acid was added to 6g of octyltrimethoxysilane and dissolved under argon protection. After removing water and alcohol byproducts from the system by distillation at 100℃ to 150℃, the first boron-containing precursor was obtained, with a boron content of 3 mmol / mL.

[0071] 2g of boric acid was added to 8g of octyltrimethoxysilane and dissolved under argon protection. After removing water and alcohol byproducts from the system by distillation at 80℃ to 120℃, the second boron-containing precursor was obtained, with a boron content of 3.3 mmol / mL.

[0072] 4.5 g of 4-methylphenylboronic acid was added to 6.5 g of tetraethoxysilane and dissolved under argon protection by heating. After removing water and alcohol byproducts from the system by distillation at 80°C to 120°C, the third boron-containing precursor was obtained. The boron content in the third boron-containing precursor was 3 mmol / mL.

[0073] 2 g of boric acid was added to 8 g of tetraethoxysilane and 20 g of octyltrimethoxysilane, and dissolved by heating under argon protection. After removing water and alcohol byproducts from the system by distillation at 80°C to 120°C, the fourth boron-containing precursor was obtained. The boron content in the fourth boron-containing precursor was 1.1 mmol / mL.

[0074] 2 g of triethyl borate and 4.5 g of 4-methylphenylboronic acid were added to 12 g of octyltrimethoxysilane and dissolved under argon protection. After removing water and alcohol byproducts by distillation at 80°C to 120°C, the fifth boron-containing precursor was obtained. The boron content in the fifth boron-containing precursor was 3.3 mmol / mL.

[0075] In some optional embodiments, after obtaining the boron-containing quantum dots, the method further includes: mixing the boron-containing quantum dots with a boron-containing compound to form an adsorption layer on the surface of the boron-containing quantum dots.

[0076] It is understandable that when boron is introduced onto the surface of boron-containing quantum dots to form an adsorption layer, the reaction temperature at this stage is relatively low, generally between room temperature and 230°C. Therefore, boron-containing compounds that are inconvenient to use in the core / shell preparation process can be directly used in the preparation of the adsorption layer. That is, the types of boron-containing compounds used in the stage of forming the adsorption layer on the surface of boron-containing quantum dots do not need to be exactly the same as those used in the core layer 1 / shell layer 2 preparation stage. Similarly, the specific preparation method for forming the adsorption layer on the surface of boron-containing quantum dots has been disclosed as prior art in patent publications such as CN118546671A, CN114686205A, and CN113634240A, and will not be repeated here.

[0077] As a third aspect, another embodiment of the present invention provides an optical component comprising boron-containing quantum dots as described in the above embodiments, or boron-containing quantum dots prepared by the method for preparing boron-containing quantum dots as described in the above embodiments.

[0078] As a fourth aspect, another embodiment of the present invention provides an electronic device comprising boron-containing quantum dots as described in the above embodiments, or boron-containing quantum dots prepared by the method for preparing boron-containing quantum dots as described in the above embodiments.

[0079] It should be noted that the aforementioned optical components or electronic devices include, but are not limited to, quantum dot light diffusion plates, solar cell light conversion films, OLED-based quantum dot inks and on-chip packaging, QLED (quantum dot TVs), smartphones, laptops and automotive displays; LED lights, bio-imaging devices and photodetectors, etc.

[0080] The present invention will be described in detail below with reference to specific embodiments and comparative examples:

[0081] Compare with Example 1

[0082] This comparative example provides a boron-free quantum dot comprising a CdSe core layer, a CdS shell layer, and a ZnS shell layer distributed sequentially from the inside out. The preparation method of the quantum dot in this comparative example includes:

[0083] Nucleation stage: Take 5 mmol of cadmium oleate, heat to 300℃ under inert gas protection, then rapidly inject 3.1 mL of TOP-Se with a concentration of 1.5 mmol / mL, keep warm for 1 min and then rapidly cool down to obtain the CdSe core layer.

[0084] First coating stage: Take 4.4 mL of the above CdSe core layer, add 2 mmol of cadmium oleate, heat to 300℃ and add 5.3 mmol of TOP-S. After cooling, CdS shell layer is obtained by coating the surface of CdSe core layer, hereinafter referred to as CdSe / CdS.

[0085] Second coating stage: Take the above CdSe / CdS material, mix with 10 mmol of zinc oleate, heat to 300℃ and add 10 mmol of TOP-S. After cooling, a ZnS shell is obtained by coating the CdS shell, i.e., CdSe / CdS / ZnS quantum dots.

[0086] Example 1-a

[0087] This embodiment provides a boron-containing quantum dot, comprising a CdSe core layer, a CdS shell layer, and a ZnS shell layer distributed sequentially from the inside out, with boron element introduced into the CdSe core layer. The preparation method of the boron-containing quantum dot in this embodiment includes:

[0088] Nucleation stage: 5 mmol of cadmium oleate was taken, and a boron-containing precursor with a boron element molar concentration of 3.3 mmol / mL was added simultaneously. The boron-containing compound in the boron-containing precursor was boric acid, and the silane compound was octyltrimethoxysilane. The preparation process for the second boron-containing precursor described above was followed. The mixture was then heated to 300 °C under inert gas protection, and then 3.1 mL of TOP-Se with a concentration of 1.5 mmol / mL was rapidly injected. After holding at this temperature for 1 min, the mixture was rapidly cooled to obtain the boron-containing CdSe core layer.

[0089] The first and second encapsulation stages of this embodiment are the same as those in Comparative Example 1.

[0090] Example 1-b

[0091] This embodiment provides a boron-containing quantum dot, comprising a CdSe core layer, a CdS shell layer, and a ZnS shell layer distributed sequentially from the inside out, with boron element introduced into the ZnS shell layer. The preparation method of the boron-containing quantum dot in this embodiment includes:

[0092] The nucleation stage and the first encapsulation stage in this embodiment are the same as those in Comparative Example 1.

[0093] Second coating stage: Take the CdSe / CdS material coated once above, mix with 10 mmol of zinc oleate, heat to 300℃, and simultaneously add a boron-containing precursor with a boron element molar concentration of 3 mmol / ml. The boron-containing precursor reactants include 4-methylphenylboronic acid and tetraethoxysilane. The preparation process follows the same procedure as the third boron-containing precursor described above. Then, 10 mmol of TOP-S is added dropwise, followed by cooling to obtain boron-containing CdSe / CdS / ZnS quantum dots with a ZnS shell.

[0094] Example 1-c

[0095] This embodiment provides a boron-containing quantum dot, comprising a CdSe core layer, a CdS shell layer, and a ZnS shell layer distributed sequentially from the inside out, with boron element introduced into the CdSe core layer and the ZnS shell layer. The preparation method of the boron-containing quantum dot in this embodiment includes:

[0096] The nucleation stage in this embodiment is the same as in Example 1-a, and the first encapsulation stage is the same as in Comparative Example 1. The second encapsulation stage is the same as in Example 1-b.

[0097] Example 1-d

[0098] This embodiment provides a boron-containing quantum dot, comprising a CdSe core layer and a CdS shell layer distributed sequentially from the inside out, with boron element introduced into the CdS shell layer. The preparation method of the boron-containing quantum dot in this embodiment includes:

[0099] The nucleation stage in this embodiment is the same as that in Comparative Example 1.

[0100] Coating stage: Take 4.4 mL of the above CdSe core layer and add 2 mmol of cadmium oleate. Simultaneously, add a boron-containing precursor with a boron element molar concentration of 3 mmol / mL. The boron-containing compound in the boron-containing precursor reaction is 4-methylphenylboronic acid, and the silane compound is tetraethoxysilane. The preparation process follows the same procedure as the third boron-containing precursor described above. Then, heat the mixture to 300℃, followed by the dropwise addition of 5.3 mmol of TOP-S. After the addition is complete, cool down to obtain CdSe / CdS quantum dots with a boron-containing CdS shell.

[0101] Example 1-e

[0102] This embodiment provides a boron-containing quantum dot, comprising a CdSe core layer, a CdS shell layer, and a ZnS shell layer distributed sequentially from the inside out, with a moderate amount of boron introduced into the CdSe core layer and the ZnS shell layer. The specific preparation method includes:

[0103] The overall preparation steps in this embodiment are the same as in Example 1-c, the only difference being that the amount of boron-containing precursor used in the nucleation stage and the second coating stage is increased by 5 times.

[0104] Example 1-f

[0105] This embodiment provides a boron-containing quantum dot, comprising a CdSe core layer, a CdS shell layer, and a ZnS shell layer distributed sequentially from the inside out, with a large amount of boron element introduced into the CdSe core layer and the ZnS shell layer. The specific preparation method includes:

[0106] The overall preparation steps in this embodiment are the same as in Example 1-c, the only difference being that the amount of boron-containing precursor used in the nucleation stage and the second coating stage is increased by 25 times.

[0107] Example 1-g

[0108] This embodiment provides a boron-containing quantum dot, comprising a CdSe core layer, a CdS shell layer, and a ZnS shell layer distributed sequentially from the inside out, with boron element introduced after the synthesis of the boron-containing quantum dot. The specific preparation method includes:

[0109] Take the boron-free CdSe / CdS / ZnS quantum dots from Comparative Example 1, dissolve them in chloroform solution, and add 4-methylphenylboronic acid, the amount of which is 0.33 times the mass of the quantum dots. After mixing and stirring at room temperature for 2 hours, evaporate the supernatant containing the quantum dots and 4-methylphenylboronic acid to dryness using a rotary evaporator to obtain solid CdSe / CdS / ZnS quantum dots with a moderate amount of boron on the surface.

[0110] Example 1-h

[0111] This embodiment provides a boron-containing quantum dot, comprising a CdSe core layer, a CdS shell layer, and a ZnS shell layer distributed sequentially from the inside out, with boron element introduced after the synthesis of the boron-containing quantum dot. The specific preparation method includes:

[0112] Take the boron-free CdSe / CdS / ZnS quantum dots from Comparative Example 1, dissolve them in chloroform solution, and add 4-methylphenylboronic acid, the amount of which is 10 times the mass of the quantum dots. After mixing and stirring at room temperature for 2 hours, evaporate the supernatant containing the quantum dots and 4-methylphenylboronic acid to dryness using a rotary evaporator to obtain solid CdSe / CdS / ZnS quantum dots with a large amount of boron on the surface.

[0113] Compare with Example 2

[0114] This comparative example provides a boron-free quantum dot comprising a CdSeS core layer, a CdS shell layer, and a ZnS shell layer distributed sequentially from the inside out. The preparation method of the quantum dot in this comparative example includes:

[0115] Nucleation stage: Take 20 mmol of cadmium oleate, heat to 320℃ under inert gas protection, then rapidly inject 4.6 mL of Se and S mixed precursor with a concentration of 1 mmol / mL, keep warm for 1 min and then rapidly cool down to obtain CdSeS core layer.

[0116] First coating stage: Take 4.4 mL of the above CdSeS core layer, add 4 mmol of cadmium oleate, heat to 300℃ and add 10.3 mmol of TOP-S. After cooling, the CdS shell layer is obtained by coating the surface of the CdSe core layer, hereinafter referred to as CdSeS / CdS.

[0117] Second coating stage: Take the above CdSeS / CdS material, mix with 10 mmol of zinc oleate, heat to 300℃ and add 10 mmol of TOP-S. After cooling, a ZnS shell is obtained by coating the CdS shell, i.e., CdSe / CdS / ZnS quantum dots.

[0118] Example 2-a

[0119] This embodiment provides a boron-containing quantum dot, comprising a CdSeS core layer, a CdS shell layer, and a ZnS shell layer distributed sequentially from the inside out, with boron element introduced into the CdSeS core layer. The preparation method of the boron-containing quantum dot in this embodiment includes:

[0120] Nucleation stage: 20 mmol of cadmium oleate was taken, and a boron-containing precursor with a boron element molar concentration of 3.3 mmol / mL was added simultaneously. The boron-containing compound in the boron-containing precursor was boric acid, and the silane compound was octyltrimethoxysilane. The preparation process for the second boron-containing precursor described above was followed. The mixture was then heated to 320 °C under inert gas protection, and then 4.6 mL of a Se / S mixed precursor with a concentration of 1 mmol / mL was rapidly injected. After holding at this temperature for 1 min, the temperature was rapidly lowered to obtain the boron-containing CdSeS core layer.

[0121] The first and second encapsulation stages of this embodiment are the same as those in Comparative Example 2.

[0122] Example 2-b

[0123] This embodiment provides a boron-containing quantum dot, comprising a CdSeS core layer, a CdS shell layer, and a ZnS shell layer distributed sequentially from the inside out, with boron element introduced into the ZnS shell layer. The preparation method of the boron-containing quantum dot in this embodiment includes:

[0124] The nucleation stage and the first encapsulation stage in this embodiment are the same as those in Comparative Example 2.

[0125] Second coating stage: Take the CdSeS / CdS material coated once above, mix with 10 mmol of zinc oleate, heat to 300℃, and simultaneously add a boron-containing precursor with a boron element molar concentration of 3 mmol / ml. The boron-containing precursor reactants include 4-methylphenylboronic acid and tetraethoxysilane. The preparation process follows the same procedure as the third boron-containing precursor described above. Then, 10 mmol of TOP-S is added dropwise, followed by cooling to obtain boron-containing CdSeS / CdS / ZnS quantum dots with a ZnS shell.

[0126] Example 2-c

[0127] This embodiment provides a boron-containing quantum dot, comprising a CdSeS core layer, a CdS shell layer, and a ZnS shell layer distributed sequentially from the inside out, with boron element introduced into the CdSeS core layer and the ZnS shell layer. The preparation method of the boron-containing quantum dot in this embodiment includes:

[0128] The nucleation stage in this embodiment is the same as in Example 2-a, and the first encapsulation stage is the same as in Comparative Example 1. The second encapsulation stage is the same as in Example 2-b.

[0129] Compare with Example 3

[0130] This comparative example provides a boron-free quantum dot comprising a CdZnSeS core layer and a ZnS shell layer distributed sequentially from the inside out. The preparation method of the quantum dot in this comparative example includes:

[0131] Nucleation stage: Mix 2 mmol of cadmium oleate and 10 mmol of zinc oleate, heat to 340℃ under inert gas protection, inject 4 mmol of Se and S mixed precursor, keep warm for 2 min, and cool down to obtain CdZnSeS core layer.

[0132] Coating stage: Take the above CdZnSeS core layer and mix it with 20 mmol of zinc oleate, heat it to 300℃, add 10 mmol of TOP-S dropwise, and cool it down after the addition is complete to obtain CdZnSeS / ZnS quantum dots.

[0133] Example 3-a

[0134] This embodiment provides a boron-containing quantum dot, comprising a CdZnSeS core layer and a ZnS shell layer distributed sequentially from the inside out, with boron element introduced into the CdZnSeS core layer. The preparation method of the boron-containing quantum dot in this embodiment includes:

[0135] Nucleation stage: 2 mmol of cadmium oleate and 10 mmol of zinc oleate were mixed and heated to 340 °C under inert gas protection. 4 mmol of a Se / S mixed precursor was injected and held at this temperature for 2 min. Simultaneously, a boron-containing precursor with a boron element molar concentration of 1.1 mmol / ml was added. The boron-containing compound in the boron-containing precursor was boric acid, and the silane compound was octyltrimethoxysilane. The preparation was carried out according to the same procedure as the second boron-containing precursor described above. Cooling was then performed to obtain a boron-containing CdZnSeS core layer.

[0136] The encapsulation stage in this embodiment is the same as in Comparative Example 3.

[0137] Example 3-b

[0138] This embodiment provides a boron-containing quantum dot, comprising a CdZnSeS core layer and a ZnS shell layer distributed sequentially from the inside out, with boron element introduced into the ZnS shell layer. The preparation method of the boron-containing quantum dot in this embodiment includes:

[0139] The nucleation stage in this embodiment is the same as that in Control Example 3.

[0140] Coating stage: The above-mentioned CdZnSeS core layer was mixed with 20 mmol of zinc oleate, and the mixture was heated to 300℃. Simultaneously, a boron-containing compound precursor with a boron element molar concentration of 3 mmol / ml was added. The boron-containing compound in the boron-containing precursor was 4-methylphenylboronic acid, and the silane compound was tetraethoxysilane. The preparation was carried out according to the preparation process of the third boron-containing precursor described above. Then, 10 mmol of TOP-S was added dropwise, and the mixture was cooled after the addition was complete to obtain CdZnSeS / ZnS quantum dots with a boron-containing shell.

[0141] Example 3-c

[0142] This embodiment provides a boron-containing quantum dot, comprising a CdZnSeS core layer and a ZnS shell layer distributed sequentially from the inside out, with boron element introduced into the CdZnSeS core layer and the ZnS shell layer. The preparation method of the boron-containing quantum dot in this embodiment includes:

[0143] The nucleation stage in this embodiment is the same as in Embodiment 3-a, and the encapsulation stage is the same as in Embodiment 3-b.

[0144] Compare with Example 4

[0145] This comparative example provides a boron-containing quantum dot comprising a CdZnSeS core layer and a ZnS shell layer distributed sequentially from the inside out, with boron element introduced after the synthesis of the boron-containing quantum dot. The specific preparation method includes:

[0146] Take the boron-free CdZnSeS / ZnS quantum dots from Comparative Example 3, add 4-methylphenylboronic acid with a boron molar concentration of 3 mmol / ml, mix and stir at room temperature for 1 hour to obtain CdZnSeS / ZnS quantum dots with boron on the surface.

[0147] The relevant performance parameters of the boron-containing quantum dots in Examples 1 to 3 are shown in Table 1, and the structural characteristics and relevant performance parameters of the boron-containing quantum dots in Comparative Examples 1 to 3 are shown in Table 2.

[0148] Table 1. Relevant performance parameters of boron-containing quantum dots in Examples 1 to 3

[0149]

[0150] Table 2. Structural characteristics and related performance parameters of boron-containing quantum dots in Comparative Examples 1 to 3

[0151]

[0152] (I) Purification Experiment of Boron-Containing Quantum Dots

[0153] Quantum dot solutions from Example 3-c, Control Examples 3, and 4 were used. Octane was used as the solvent and ethanol as the precipitant. Boron in the adsorbed layer outside the quantum dot structure was removed by a dissolution-precipitation purification method. The single-round purification process was as follows: 100 mg of quantum dot material was dispersed in 10 mL of octane solvent and fully dissolved. 10 mL of ethanol precipitant was added, mixed thoroughly, and the solution was discarded by centrifugation to obtain the quantum dot material precipitate. Quantum dot materials from Example 3-c, Control Examples 3, and 7, and Control Examples 4 were purified in 3 / 7 / 11 rounds, respectively. The contents of Zn, Cd, Se, S, and B were determined by ICP-OES. The results are shown in Table 3.

[0154] Table 3. Elemental content of quantum dot materials from purification cycles 3 / 7 / 11 in Example 3-c and Control Example 3 and Control Example 4.

[0155]

[0156] As shown in Table 3, even after multiple rounds of purification (3 / 7 / 11), the concentrations and proportions of elements other than boron remained almost unchanged in each group of samples. With increasing purification and washing cycles, boron bound to the quantum dot surface solely through adsorption (Control Example 4) was removed after 7 rounds of purification. In Example 3-c, the boron concentration in the quantum dot material reached a stable state after 7 rounds of purification, indicating that boron was successfully introduced into the core and shell layers of the quantum dots, and that the boron in these layers remained stable during multiple purification cycles. It should be noted that the boron concentration in the quantum dot material of Example 3-c after 7 rounds of purification was lower than that after 3 rounds of purification. This is because a certain amount of free boron remained on the surface after core layer preparation. This free boron existed through physical adhesion, and after 7 rounds of purification, it was also fully removed.

[0157] (II) Microstructure of boron-containing quantum dots

[0158] Taking Example 3-c as an example, the boron-containing quantum dots were characterized by TEM, and their dimensions were as follows: Figure 4 As shown. Furthermore, TEM images of the boron-containing quantum dots before and after boron doping of the internal lattice are shown below. Figure 5 , Figure 6 As shown. By Figure 5 , Figure 6 The comparison revealed that the undoped boron lattice was ordered and free of dislocations. After boron doping, the presence of boron atoms in the interlayer caused slight lattice dislocations, exhibiting lattice distortion caused by interlayer doping (white dashed circle). This further demonstrates that boron also forms new structures by doping into the lattice.

[0159] (III) Thermal stability experiment of boron-containing quantum dots

[0160] Quantum dot samples from Example 3-c and Control Example 3 were thoroughly purified to remove boron adhering to the quantum dot surface. Quantum dot films were then prepared on 20mm diameter circular glass slides using spin coating. A Sipu Optoelectronics integrating sphere testing system, along with the manufacturer's heating sample stage and temperature control components, was used. A staged heating program was set, increasing the temperature from 50℃ to 200℃ at a rate of 10℃ / min, followed by a 20min hold. The fluorescence quantum efficiency of the samples was continuously measured and recorded during this period. Figure 7 As shown, with the initial fluorescence quantum efficiency at 50℃ as 100%, the changes in fluorescence quantum efficiency of the samples at different temperatures were normalized; the fluorescence emission spectra of the quantum dot samples of Example 3-c and Control Example 3 at different temperatures are shown below. Figure 8 As stated above.

[0161] from Figure 7It can be seen that the fluorescence quantum efficiency of the quantum dot sample in Example 3-c is significantly higher than that of the quantum dot sample in Control Example 3 after high-temperature treatment. Specifically, the fluorescence quantum efficiency of the quantum dot sample in Control Example 3, without boron, decayed to about 90% after being kept at 200°C for 20 minutes. However, the fluorescence quantum efficiency of the sample in Example 3-c, which is doped with boron, only decayed to 94% after being kept at 200°C for 20 minutes.

[0162] Depend on Figure 8 A comparison reveals that, with increasing temperature, both the fluorescence peaks of the quantum dot samples in Example 3-c and Control Example 3 exhibited a red shift and a decrease. However, the decrease in fluorescence peak value of the quantum dot sample in Example 3-c was significantly less than that in Control Example 3, further indicating a significant improvement in the thermal stability of the boron-containing quantum dot sample in Example 3-c. Overall, compared to Control Example 3, the quantum dot sample in Example 3-c exhibits stronger optical properties and greater thermal stability.

[0163] Depend on Figure 8 Further comparison revealed that, at the same temperature (e.g., 50°C), compared to the undoped boron control 3, the fluorescence peak of the boron-doped quantum dot sample in Example 3-c exhibited a slight blue shift. This is partly because the fluorescence peak did not exhibit a red shift after boron doping, indicating that the exciton radius did not increase; and partly because the fluorescence peak showed a slight blue shift, suggesting that boron atoms interacted with the inorganic structure of the quantum dot, thus affecting the change in the electronic state of the quantum dot. Based on this phenomenon, Figure 9 The images show the UV-Vis absorption spectra of the quantum dot samples in Example 3-c and Control Example 3 (with the first exciton absorption peak normalized). Figure 9 As can be seen, the first exciton absorption peak of the quantum dot sample in Example 3-c exhibits a redshift, while its exciton radius does not increase. Combined with the TEM image of the boron-containing quantum dot lattice after boron doping, it can be inferred that the substitution of a small number of boron atoms within the lattice leads to local orbital hybridization. The substitution of Cd by B slightly contracts the lattice constant, thereby enhancing the atomic orbital overlap. The hybridization of the 2p orbital of B with the 4p orbital of Se results in a decrease in the band gap, causing the first exciton absorption peak to redshift. Therefore, based on the fluorescence emission and ultraviolet absorption spectra of the quantum dot samples before and after boron doping, it can be further confirmed that boron atoms have entered the lattice and undergone doping.

[0164] Furthermore, the boron content in the core / shell / adsorption layer was changed to increase the content of the samples in Examples 1-e, 1-f, 1-g, and 1-h.

[0165] All quantum dot samples from Examples 1 to 3 and Comparative Examples 1 to 3 were prepared as quantum dot solids and subjected to heat treatment at different temperatures in a tube muffle furnace under an argon atmosphere. The heat treatment parameters were as follows: initial temperature 20℃, heating to the target temperature at a rate of 20℃ / min, holding at the target temperature until the total heat treatment time was 30 min, and then rapidly cooling to room temperature. Specifically, at a target temperature of 200℃, the heat treatment process involved heating for 9 min and holding at that temperature for 21 min; at a target temperature of 500℃, the heat treatment process involved heating for 24 min and holding at that temperature for 6 min; and at a target temperature of 600℃, the heat treatment process involved heating for 29 min and holding at that temperature for 1 min. Finally, the fluorescence efficiency of each quantum dot solid before and after heat treatment was measured using an integrating sphere, and the results are shown in Table 4.

[0166] Table 4. Fluorescence efficiency of each quantum dot solid before and after heat treatment in Examples 1 to 3 and Comparative Examples 1 to 3.

[0167]

[0168] Table 4 shows that the quantum dots in Examples 1-a to 1-c, Examples 2-a to 2-c, and Examples 3-a to 3-c all exhibited excellent initial fluorescence efficiency, and their fluorescence efficiency remained at a high level (above 95%) even after heat treatment at 200℃. In Example 1-e, while increasing the boron content in the quantum dot core / shell layer affected the initial fluorescence efficiency, it further improved the high-temperature stability, maintaining a certain fluorescence efficiency (46.9%) even after heat treatment at 500℃. However, in Example 1-f, when the total boron content reached 34625 ppm and the boron content in the core and shell layers reached 29841 ppm, the excessive boron severely affected the nucleation and growth process of the quantum dots, resulting in an initial fluorescence efficiency of <1% and no fluorescence generation. In Examples 1-g and 1-h, boron was introduced only into the surface adsorption layer of the quantum dots. It was found that without introducing boron into the core-shell structure of the quantum dots, the boron content in the surface adsorption layer needed to reach 10000 ppm to have a certain impact on the thermal stability of the quantum dots. Therefore, compared to introducing boron only on the surface of quantum dots, this invention, by rationally controlling the boron content in the core / shell layer, can optimize the thermal stability of quantum dots and maintain high fluorescence efficiency with a relatively small amount of boron added, thus having better economic value.

[0169] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A boron-containing quantum dot, characterized in that, The quantum dot comprises a core layer and a shell layer covering the core layer; at least one of the core layer and the shell layer comprises boron and a group II-VI semiconductor compound, wherein the boron is doped into at least one of the core layer and the shell layer in the form of interlattice doping, and in the core layer and / or the shell layer, the boron is chemically bonded to a non-metallic element in the group II-VI semiconductor compound. The boron-containing quantum dot is prepared from a boron-containing precursor and a group II-VI semiconductor compound precursor, wherein the boron-containing precursor is a compound corresponding to formula I. Formula I: ; In Formula I, R1 and R2 are independently selected from hydrocarbon, aryl, alkoxy, hydroxyl and allyl groups, respectively; R3, R4 and R5 are independently selected from hydrocarbon, aryl, alkoxy, carboxyl, allyl and hydroxyl groups, respectively. The II-VI semiconductor compounds include at least one of II-VI binary compounds, II-VI ternary compounds, and II-VI quaternary compounds; The group II-VI binary compound is selected from at least one of CdS, CdSe, CdTe, CdO, ZnS, ZnSe, ZnTe and ZnO; the group II-VI ternary compound is selected from at least one of CdSeS, CdZnSe, ZnCdS and ZnSeS; and the group II-VI quaternary compound is CdZnSeS.

2. The boron-containing quantum dot according to claim 1, characterized in that, The boron-containing quantum dot further includes an adsorption layer located on the surface of the shell, the adsorption layer comprising boron.

3. The boron-containing quantum dot according to claim 1, characterized in that, The boron content in the boron-containing quantum dots is 30 to 7500 ppm; and / or, the boron content in the core layer is 10 to 1000 ppm; and / or, the boron content in the shell layer is 50 to 6000 ppm.

4. The boron-containing quantum dot according to claim 1, characterized in that, The number of shells includes one or at least two layers. When the number of shells is at least two layers and the shells include boron and group II-VI semiconductor compounds, the boron is located in any one or more of the at least two shells.

5. A method for preparing boron-containing quantum dots, characterized in that, The method for preparing boron-containing quantum dots as described in any one of claims 1 to 4 includes: sequentially preparing a core layer and a shell layer, and during the nucleation and / or shell formation process, contacting a boron-containing precursor with a group II-VI semiconductor compound precursor to obtain the boron-containing quantum dots; The boron-containing precursor is the compound corresponding to Formula I: Formula I: ; In Formula I, R1 and R2 are independently selected from hydrocarbon, aryl, alkoxy, hydroxyl and allyl groups, respectively; R3, R4 and R5 are independently selected from hydrocarbon, aryl, alkoxy, carboxyl, allyl and hydroxyl groups, respectively.

6. The method for preparing boron-containing quantum dots according to claim 5, characterized in that, During the nucleation and / or shell formation process, the boron-containing precursor is contacted with the II-VI group semiconductor compound precursor at a temperature of 250°C to 350°C to obtain the boron-containing quantum dots; The boron-containing precursor is obtained by reacting a boron-containing compound with a silicon-containing compound, wherein the boron-containing compound includes boron hydroxyl compounds and / or boron ester compounds, and the silicon-containing compound has silanoxy and / or silanol groups.

7. The method for preparing boron-containing quantum dots according to claim 5, characterized in that, After sequentially preparing the core layer and shell layer, the method further includes: mixing the boron-containing quantum dots with a boron-containing compound to form an adsorption layer on the surface of the boron-containing quantum dots.

8. An optical component, characterized in that, The optical component includes boron-containing quantum dots as described in any one of claims 1 to 4, or boron-containing quantum dots prepared by the method described in any one of claims 5 to 7.

9. An electronic device, characterized in that, The electronic device includes boron-containing quantum dots as described in any one of claims 1 to 4, or boron-containing quantum dots prepared by the method described in any one of claims 5 to 7.

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