Quantum dots, method for preparing the same, and optical component including the quantum dots

Abstract

A quantum dot, a method for preparing the same, and an optical component including the quantum dot are provided. The quantum dot includes: a core including a III-V semiconductor compound alloyed with gallium (Ga); a first shell surrounding the core; and a second shell surrounding the first shell, wherein the first shell includes a first compound including a II-VI semiconductor compound, a III-V semiconductor compound, or a III-VI semiconductor compound, the second shell includes a second compound including a II-VI semiconductor compound, a III-V semiconductor compound, or a III-VI semiconductor compound, the first compound and the second compound are different from each other, and the atomic percentage of a specific element in the material of the core, and the ratio of the elements in the first shell and the second shell relative to the core meet a certain range.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2020-0186767 filed in the Korean Intellectual Property Office on December 29, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] One or more aspects of embodiments of the present disclosure relate to quantum dots and methods of preparing the same, and optical members and electronic devices each including the quantum dots. Background Art

[0004] Quantum dots, which are nanocrystals of semiconductor materials, exhibit quantum confinement effects. When quantum dots receive light from an excitation source and reach a high-energy excited state, the quantum dots can spontaneously emit energy (e.g., light energy or photons) corresponding to the energy band gap of the quantum dots. In this regard, even when the particles are formed (composed) of the same material, the wavelength of the light emitted by the particles can also be changed according to the particle size, and accordingly, light with a desired or appropriate wavelength range can be obtained by adjusting the size of the quantum dots, thereby obtaining excellent or appropriate color purity and / or high luminous efficiency. Therefore, quantum dots can be applied to various appropriate devices or equipment.

[0005] Quantum dots can be used to perform various optical functions (e.g., light conversion functions) in optical components. For example, an optical component including quantum dots can have the form of a film, for example, a film patterned for each sub-pixel. Such an optical component can be used as a color conversion component of a device including one or more light sources.

[0006] As for the quantum dots included in the color conversion member in the art, InP-based quantum dots are mainly used. However, due to the low blue light absorption rate of InP-based quantum dots, the color conversion member in the prior art uses a color conversion member including a large number of quantum dots, or a blue light blocking film is additionally arranged on the color conversion member, which is disadvantageous. Summary of the invention

[0007] One or more aspects of the embodiments of the present disclosure are directed to quantum dots having an enhanced weight absorption coefficient, methods of preparing the same, optical members including the quantum dots, and devices including the quantum dots.

[0008] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments of the disclosure.

[0009] One or more embodiments of the present disclosure provide a quantum dot, which includes: a core including a Group III-V semiconductor compound alloyed with gallium (Ga), a first shell around the core (e.g., surrounding the core), and a second shell around the first shell (e.g., surrounding the first shell), wherein the first shell includes a first compound, the first compound includes a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound, the second shell includes a second compound, the second compound includes a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound, the first compound and the second compound are different from each other, the atomic percentage of gallium in the core relative to the Group III element other than Ga in the core is 25 atomic % to 30 atomic %, the atomic percentage of the Group V element or the Group VI element in the first shell relative to the Group III element in the core is 5 atomic % to 50 atomic %, and the atomic percentage of the Group V element or the Group VI element in the second shell relative to the Group III element in the core is 5 atomic % to 50 atomic %.

[0010] One or more embodiments of the present disclosure provide a method for preparing a quantum dot, the method comprising: preparing a first mixture in which a core including a Group III-V semiconductor compound alloyed with gallium (Ga) is dispersed in an organic solvent at a concentration of 0.1 mM to 100 mM; forming a first shell by reacting a second mixture, the second mixture being obtained by adding a first precursor including a Group V element or a Group VI element and a second precursor including a Group II element or a Group III element to the first mixture; and forming a second shell by reacting a third mixture, the third mixture being obtained by adding a first precursor including a Group V element or a Group VI element and a second precursor including a Group II element or a Group III element to the first mixture. A second precursor comprising a Group II element or a Group VI element and a fourth precursor comprising a Group II element or a Group III element are added to the reacted second mixture, wherein the atomic percentage (%) of gallium in the core relative to the Group III element other than Ga is 25 atomic % to 30 atomic %, the first precursor and the third precursor are different from each other, the first shell comprises a Group II-VI semiconductor compound, a Group III-V semiconductor compound or a Group III-VI semiconductor compound, and the second shell comprises a Group II-VI semiconductor compound, a Group III-V semiconductor compound or a Group III-VI semiconductor compound.

[0011] One or more embodiments of the present disclosure provide an optical member including quantum dots.

[0012] One or more embodiments of the present disclosure provide an electronic device including quantum dots. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and other aspects, features and advantages of selected embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0014] Figure 1 is a schematic diagram showing the structure of a quantum dot according to an embodiment;

[0015] Figure 2 shows a transmission electron microscope (TEM) image of quantum dots according to an embodiment;

[0016] Figure 3A shows a TEM image of quantum dots prepared using a preparation method according to an embodiment;

[0017] Figure 3B shows a TEM image of quantum dots prepared using a preparation method according to an embodiment;

[0018] Figure 4 showing line graphs of valley-to-peak ratio (V to P) in absorption spectra and full width at half maximum (FWHM) in photoluminescence spectra of InGaP core quantum dots having atomic percentages of Ga / In of 26 atomic %, 45 atomic % or 55 atomic %, respectively; and

[0019] Figure 5 The absorbance of the quantum dot compositions prepared in Preparation Examples 4 and 8 with respect to wavelength (eg, absorption spectrum) is shown. DETAILED DESCRIPTION

[0020] The embodiments in the accompanying drawings will now be explained in more detail with reference to their examples, wherein the same reference numerals refer to the same elements throughout, and a repeated description thereof may not be provided. In this regard, the present embodiment may have different forms and should not be construed as being limited to the description set forth herein. Accordingly, the following merely describes the embodiments with reference to the accompanying drawings to explain aspects of the present description. As used herein, the term "and / or" includes any and all combinations of one or more related enumerated items. Throughout this disclosure, the expression "at least one of a, b, and c" indicates only a, only b, only c, both a and b (e.g., a and b at the same time), both a and c (e.g., a and c at the same time), both b and c (e.g., b and c at the same time), all a, b, and c or variations thereof.

[0021] Because the present disclosure is capable of various suitable transformations and can have various suitable embodiments, it will be illustrated in the drawings, and selected embodiments will be described in more detail in the detailed description. The effects and features of the present disclosure and methods for achieving them will become clear with reference to the embodiments described in more detail in conjunction with the drawings. However, the present disclosure is not limited to the following embodiments and can be implemented in various suitable forms.

[0022] As used herein, the terms “first” and / or “second” and the like are not limited to relevant components but are used for the purpose of distinguishing one component from another.

[0023] As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0024] As used herein, terms such as "include", "comprising" and / or "having" specify the presence of the described features, integers, processes, operations, elements, components and / or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, processes, operations, elements, components and / or combinations thereof. For example, terms such as "include", "comprising" and / or "having", unless otherwise limited, may refer to the case consisting of only the features or components described in the specification, as well as the case further including other features and / or components.

[0025] As used herein, the terms "use," "using," and "used" may be considered synonymous with the terms "utilize," "utilizing," and "utilized," respectively. Expressions such as "at least one of," "one of," and "selected from," when preceding / following a list of elements, modify the entire list of elements and do not modify the individual elements of the list. The term "and / or" includes any and all combinations of one or more of the associated listed items. Further, the use of "may" when describing embodiments of the present disclosure refers to "one or more embodiments of the present disclosure."

[0026] As used herein, "Group II elements" may include Group IIA elements and / or Group IIB elements of the IUPAC periodic table. Examples of Group II elements may include magnesium (Mg) and / or zinc (Zn), but are not limited thereto.

[0027] As used herein, "Group III elements" may include Group IIIA elements and Group IIIB elements of the IUPAC periodic table. Examples of Group III elements may include aluminum (Al), indium (In), gallium (Ga) and / or thallium (Tl), but are not limited thereto.

[0028] As used herein, "Group V elements" may include Group VA elements and / or Group VB elements of the IUPAC periodic table. Examples of Group V elements may include phosphorus (P), arsenic (As) and / or antimony (Sb), but are not limited thereto.

[0029] As used herein, "Group VI elements" may include Group VIA elements and / or Group VIB elements of the IUPAC periodic table. Examples of Group VI elements may include oxygen (O), sulfur (S), selenium (Se) and / or tellurium (Te), but are not limited thereto.

[0030] As used herein, "atomic percent" refers to the percentage of the number of atoms of a first atom (element) relative to the number of atoms of a second atom (element), for example, the ratio of the number of atoms of the first element to 100 atoms of the second element.

[0031] As used herein, "sphericity" is a measure of the degree of sphericity (roundness) of an object and a measure of the compactness of a shape. According to Wadell, H., "Volume, Shape, and Roundness of Quartz Particles," J. of Geology 43:250-280 (1935), the sphericity (ψ) of a particle is defined by Equation 1:

[0032] Equation 1

[0033] Ψ=(π 1 / 3 (6V p ) 2 / 3 ) / A p .

[0034] In Equation 1, V p is the volume of the particle, and A p is the surface area of ​​the particle. The sphericity of a sphere (eg, a perfect sphere) is 1, and any non-spherical particle has a sphericity less than 1.

[0035] As used herein, "weight absorption coefficient" or "mass extinction coefficient" is a coefficient used to quantify the absorption of a given mass (weight) of quantum dots to light of a specific wavelength, and is calculated using the following equation based on the Lambert-Beer law. As used herein, the "weight" or "mass" in the term "weight absorption coefficient" or "mass extinction coefficient" may refer to weight in grams. The weight absorption coefficient is defined by Equation 2:

[0036] Equation 2

[0037] Weight absorption coefficient (a) = A / c·L.

[0038] In Equation 2, A is absorbance, c is the concentration of the sample solution (g / mL), and L is the length of the sample solution (cm).

[0039] As used herein, the terms "quantum efficiency" and "luminous efficiency" are used interchangeably.

[0040] Below, we will refer to Figure 1Embodiments of quantum dots 10 and methods of making the same are described.

[0041] Quantum dot 10

[0042] According to an embodiment, the quantum dot includes: a core 10a including a Group III-V semiconductor compound alloyed with gallium (Ga); a first shell 10b surrounding the core 10a; and a second shell 10c surrounding the first shell 10b, wherein the first shell 10b includes a first compound, the first compound may include a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound, the second shell 10c includes a second compound, the second compound may include a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound, and the first compound and the second compound are different from each other (for example, the composition of the second shell 10c is different from the composition of the first shell 10b), and the atomic percentage (%) of Ga in the core 10a relative to the Group III element other than Ga in the core 10a may be about 25 atomic % to about 30 atomic %. For example, based on the number of atoms of the Group III element other than Ga in the core 10a, the number of atoms of Ga in the core 10a may be about 25 atomic % to about 30 atomic %.

[0043] The amounts of Ga and Group III elements other than Ga in the core 10a may each be measured by qualitative analysis and / or quantitative analysis of elements constituting a sample, for example, by analysis of binding energy measured using X-ray photoelectron spectroscopy (XPS). However, the embodiment is not limited thereto.

[0044] In one or more embodiments, the Group III-V semiconductor compound alloyed with Ga may include InGaP. For example, the atomic percentage of Ga relative to In (eg, Ga / In) in the core 10a including InGaP may be about 25 atomic % to about 30 atomic %.

[0045] In a quantum dot having a core / shell structure with a band gap (e.g., band gap difference) that is too large between the core and the shell, the quantum dot may have reduced quantum efficiency and / or stability. For example, in a quantum dot structure such as InP / ZnSe, the quality of the quantum dot may be degraded due to lattice defects caused by a large band gap difference between InP as a core material and ZnSe as a shell material. When Ga is present in the lattice of a III-V semiconductor compound, the band gap increases compared to a pure III-V semiconductor compound. Therefore, the quantum dot 10 according to an embodiment may have a reduced band gap difference between the material of the core 10a and the material of the first shell 10b surrounding the core 10a, and therefore has improved quantum efficiency, stability, and / or color reproducibility.

[0046] When the band gap difference between the material of the core 10a and the material of the first shell 10b is too small (e.g., insufficient), the luminous efficiency and / or weight absorption coefficient, etc. of the quantum dot 10 may be deteriorated. By including the core 10a including a III-V semiconductor compound alloyed with Ga, the quantum dot 10 according to one or more embodiments may optimize or improve the band gap difference between the material of the core 10a and the material of the first shell 10b. Further, when the amount of Ga in the core 10a is controlled or selected to be within the above range, the quantum dot 10 according to one or more embodiments may have high quantum efficiency, photochemical stability, and / or color reproducibility.

[0047] The quantum dot 10 according to one or more embodiments may satisfy the amount of Ga in the above range in the core 10a, and thus may have a high weight absorption coefficient. For example, the quantum dot 10 may have a higher weight absorption coefficient than a quantum dot including a group III-V core (which does not include Ga). Accordingly, when applied to an optical member (e.g., a color conversion member), the quantum dot 10 may exhibit high quantum efficiency and / or color reproducibility, and / or may have high color conversion efficiency.

[0048] For example, when the atomic percentage of Ga in the core 10a relative to the group III element other than Ga in the core 10a is 25 atomic % or more, the quantum dot 10 can have a high weight absorption coefficient (at 450 nm), and thus can effectively absorb blue light from the light source. When the atomic percentage of Ga in the core 10a relative to the group III element other than Ga in the core 10a is 30 atomic % or less, because the surface defect density of the alloy core is low, the error of the luminescence peak can be minimized or reduced, and high color purity can be exhibited.

[0049] In one or more embodiments, the III-V semiconductor compound alloyed with Ga may have an absorption peak (e.g., peak absorption wavelength) of about 420 nm to about 435 nm. For example, in the absorption spectrum of the III-V semiconductor compound alloyed with Ga, the first exciton absorption peak may have a wavelength of about 420 nm to about 435 nm. Accordingly, the III-V semiconductor compound alloyed with Ga may absorb blue light within the above wavelength range and may emit green light or red light. The emission wavelength of the light emitted by the quantum dot 10 may be controlled or selected by adjusting the thickness of the shell (the first shell 10b and / or the second shell 10c) and / or the size of the quantum dot 10, etc.

[0050] In one or more embodiments, in the absorption spectrum of the III-V semiconductor compound alloyed with Ga, the first exciton region may have a valley-to-peak ratio (V to P) of 0.6 to 0.8. When the minimum absorbance at the valley region in the first exciton region of the absorption spectrum of the III-V semiconductor compound alloyed with Ga is defined as A, and the maximum absorbance at the peak region is defined as B, the result of A divided by B is defined as the valley-to-peak ratio. When the valley-to-peak ratio of the III-V semiconductor compound alloyed with Ga satisfies the above range, the quantum dot 10 may have a high quantum efficiency and a narrow full width at half maximum (FWHM). Further, when the valley-to-peak ratio satisfies the above range, the plurality of quantum dots 10 may have a dense distribution of particles (e.g., a narrow size distribution) and a substantially uniform energy band distribution.

[0051] When the first shell 10 b and the second shell 10 c each independently include a Group III-V semiconductor compound, the Group III-V semiconductor compound of the core 10 a may be different from the Group III-V semiconductor compound of the first shell 10 b and the Group III-V semiconductor compound of the second shell 10 c .

[0052] In one or more embodiments, as the material of the first shell 10b and the second shell 10c, the II-VI semiconductor compound may include ZnSe, ZnS, ZnTe, ZnO, ZnMgSe, ZnMgS or any combination thereof, the III-V semiconductor compound may include GaP, GaAs, GaSb, InAs, InSb, AlP, AlAs, AlSb or any combination thereof, and the III-VI semiconductor compound may include GaSe, GaTe or any combination thereof.

[0053] In one or more embodiments, the first shell 10b may include ZnSe, and the second shell 10c may include ZnS.

[0054] The atomic percentage of the Group V element or the Group VI element in the first shell 10b relative to the Group III element in the core 10a may be about 5 atomic % to about 50 atomic %. The number of atoms of the Group V element or the Group VI element in the first shell 10b may be about 5 atomic % to about 50 atomic % based on the number of atoms of the Group III element in the core 10a.

[0055] The atomic percentage of the Group V element or the Group VI element in the second shell 10c relative to the Group III element in the core 10a may be about 5 atomic % to about 50 atomic %. For example, the number of atoms of the Group V element or the Group VI element in the second shell 10c may be about 5 atomic % to about 50 atomic % based on the number of atoms of the Group III element in the core 10a.

[0056] The thickness of the shell of the quantum dot 10 may vary according to the atomic percentage of the Group V element or the Group VI element relative to the Group III element in the core 10a. When the amount of the Group V element or the Group VI element in each shell relative to the amount of the Group III element in the core 10a satisfies the above range, the thickness of each shell may be controlled or selected to be within a desired or appropriate range, and thus the quantum dot 10 may have a high sphericity and weight absorption coefficient.

[0057] For example, the amount of the Group V element or the Group VI element in the first shell 10 b and the second shell 10 c may be measured by qualitative analysis and quantitative analysis of elements of a sample, such as analysis of binding energy measured by X-ray photoelectron spectroscopy (XPS).

[0058] For example, the core 10a may include InGaP, the first shell 10b may include ZnSe, the second shell 10c may include ZnS, the atomic percentage of Se in the first shell 10b relative to In in the core 10a may be about 5 atomic % to about 50 atomic %, and the atomic percentage of S in the second shell 10c relative to In in the core 10a may be about 5 atomic % to about 50 atomic %.

[0059] For example, the smaller the amount (number of atoms) of the Group V element or the Group VI element in the first shell 10b and / or the second shell 10c relative to the number of atoms of the Group III element in the core 10a, the higher the sphericity of the quantum dot 10. However, embodiments are not limited thereto.

[0060] Figure 2 A transmission electron microscope (TEM) image of a quantum dot according to an embodiment is shown, the quantum dot having an InGaP / ZnSe / ZnS structure (e.g., an InGaP core having shells of ZnSe and ZnS sequentially formed thereon), having an atomic percentage of Se (or S) of 5 atomic % relative to In or an atomic percentage of Se (or S) of 30 atomic % relative to In. Figure 2 It was found that quantum dots with 5 atomic % of Se (or S) relative to In exhibited higher sphericity than quantum dots with 30 atomic % of Se (or S) relative to In.

[0061] In one or more embodiments, the atomic percentage of the Group V element or the Group VI element in the first shell 10b relative to the Group III element in the core 10a may be about 10 atomic % to about 15 atomic %, and the atomic percentage of the Group V element or the Group VI element in the second shell 10c relative to the Group III element in the core 10a may be about 10 atomic % to about 15 atomic %. When the amount of the Group V element or the Group VI element in each shell of the quantum dot 10 satisfies the above range, the quantum dot 10 may have high sphericity and high weight absorption coefficient.

[0062] In one or more embodiments, the first shell 10b and the second shell 10c may each independently include different Group II-VI semiconductor compounds, the atomic percentage of the Group VI element in the first shell 10b relative to the Group III element in the core 10a may be about 10 atomic % to about 15 atomic %, and the atomic percentage of the Group VI element in the second shell 10c relative to the Group III element in the core 10a may be about 10 atomic % to about 15 atomic %. When the amount of the Group VI element in each shell of the quantum dot 10 satisfies the above range, the quantum dot 10 may have a high weight absorption coefficient.

[0063] For example, the core 10a may include InGaP, the first shell 10b may include ZnSe, the second shell 10c may include ZnS, the atomic percentage of Se in the first shell 10b relative to In in the core 10a may be about 10 atomic % to about 15 atomic %, and the atomic percentage of S in the second shell 10c relative to In in the core 10a may be about 10 atomic % to about 15 atomic %.

[0064] In one or more embodiments, the quantum dot 10 may further include a ligand chemically bonded to its surface. The ligand may chemically bond to the surface of the quantum dot 10 to passivate the quantum dot 10. For example, the quantum dot 10 may further include a ligand chemically bonded to the second shell 10c.

[0065] The ligand may include an organic ligand or a metal halide.

[0066] For example, the organic ligand can include oleic acid, oleylamine, octylamine, decylamine, trioctylamine, hexadecylamine, mercaptopropionic acid, dodecanethiol, 1-octanethiol, thionyl chloride, trioctylphosphine, trioctylphosphine oxide, hexylphosphonic acid, tetradecylphosphonic acid, octylphosphonic acid, or any combination thereof.

[0067] In one or more embodiments, the quantum dot 10 may have a molecular weight of about 350 mL·g at a wavelength of 450 nm. -1 cm -1 About 1,000 mL·g -1 cm -1 For example, the quantum dot 10 may have a weight absorption coefficient of about 500 mL·g at a wavelength of 450 nm. -1 cm -1 About 1,000 mL·g -1 cm -1 When the weight absorption coefficient of the quantum dot 10 satisfies the above range, the quantum dot 10 may have a high absorbance of blue light. Accordingly, when applied to an optical member, for example, a color conversion member, the quantum dot 10 may have a high color conversion efficiency.

[0068] In one or more embodiments, the quantum dot 10 may have a sphericity of about 0.7 to about 1.0. For example, the quantum dot 10 may have a sphericity of about 0.7 to about 0.9.

[0069] As a method for measuring the sphericity of quantum dots 10, any appropriate method in the art can be used. For example, the sphericity of quantum dots 10 can be measured using a transmission electron microscope (TEM) image. TEM is an imaging technique in which an electron beam is directed through a sample to form an image, and the image is magnified to appear on a fluorescent screen or photographic film layer, or detected with a sensor such as a charge coupled device (CCD) camera. Using TEM, information such as the particle size, particle size distribution, and / or particle shape of the nanoparticles can be calculated.

[0070] In one or more embodiments, the sphericity of the quantum dot 10 may be measured by TEM and image observation using an image analysis tool (eg, software). However, the embodiment is not limited thereto.

[0071] In one or more embodiments, the quantum dot 10 may have a quantum efficiency of about 90% or greater, for example, about 92% or greater.

[0072] The quantum dot 10 may emit visible light other than blue light. For example, the quantum dot 10 may emit light having a maximum emission wavelength of about 495 nm to about 750 nm. Accordingly, the quantum dot 10 may be designed to absorb blue light and emit green or red light when applied to an optical member, for example, a color conversion member.

[0073] In one or more embodiments, the quantum dot 10 may emit green light having a maximum emission wavelength of about 495 nm to about 570 nm, for example, about 500 nm to about 550 nm or about 520 nm to about 530 nm. In other embodiments, the quantum dot 10 may emit red light having a maximum emission wavelength of about 630 nm to about 750 nm, for example, about 630 nm to about 700 nm or about 630 nm to about 680 nm. Accordingly, for example, when applied to a color conversion member, the quantum dot 10 may implement green light or red light having high brightness and high color purity.

[0074] In one or more embodiments, the photoluminescence (PL) spectrum of the quantum dot 10 may have a maximum emission wavelength of about 495 nm to about 750 nm. For example, the PL spectrum of the quantum dot 10 may have a maximum emission wavelength of about 495 nm to about 570 nm, for example, about 500 nm to about 550 nm or about 520 nm to about 530 nm. Accordingly, for example, when the quantum dot 10 is applied to a color conversion member, the color conversion member can provide green light with high color purity. In other embodiments, the PL spectrum of the quantum dot 10 may have a maximum emission wavelength of about 630 nm to about 750 nm, for example, about 630 nm to about 700 nm or about 630 nm to about 680 nm. Accordingly, for example, when the quantum dot 10 is applied to a color conversion member, the color conversion member can provide red light with high color purity.

[0075] For example, when the atomic percentage of Ga / Group III elements other than Ga in the core 10a satisfies the above range, the maximum emission wavelength of the PL spectrum can be about 525nm to about 530nm. Accordingly, the quantum dot 10 can emit green light with high color purity.

[0076] In one or more embodiments, the PL spectrum of the quantum dot 10 may have a full width at half maximum (FWHM) of 40 nm or less. When the FWHM of the quantum dot 10 satisfies the above range, the quantum dot 10 may provide excellent or appropriate color purity and / or color reproducibility, and / or an improved viewing angle.

[0077] In one or more embodiments, the first shell 10b may have a thickness of about 0.5 nm to about 3 nm, for example, about 0.5 nm to about 2 nm. However, the embodiment is not limited thereto. When the thickness of the first shell 10b satisfies the above range, the quantum dot 10 may have high sphericity and high weight absorption coefficient.

[0078] In one or more embodiments, the second shell 10c may have a thickness of about 0.5 nm to about 4 nm, for example, about 0.5 nm to about 1 nm. However, the embodiment is not limited thereto. When the thickness of the second shell 10c satisfies the above range, the quantum dot 10 may have high sphericity and high weight absorption coefficient.

[0079] The thickness of the first shell 10b and the thickness of the second shell 10c may each be independently changed according to the amount of the Group V element or the Group VI element in each shell relative to the amount of the Group III element in the core 10a. For example, the higher the amount of the Group V element or the Group VI element in each shell becomes relative to the amount of the Group III element in the core, the greater the thickness of each shell becomes (for example, the thickness of each shell tends to increase). However, the embodiment is not limited thereto.

[0080] In one or more embodiments, the quantum dot 10 may further include a mixed layer in which the material of the first shell 10b and the material of the second shell 10c are mixed at the interface between the first shell 10b and the second shell 10c. The mixed layer may have a concentration gradient, wherein the concentration of the material of the first shell 10b and / or the material of the second shell 10c increases or decreases toward the center (e.g., the center of the quantum dot 10). For example, the concentration of the material of the first shell 10b in the mixed layer may increase toward the center. For another example, the concentration of the material of the second shell 10c in the mixed layer may decrease toward the center.

[0081] In one or more embodiments, the quantum dot 10 may have an average particle size of about 1 nm to about 20 nm. For example, the quantum dot 10 may have an average particle size of about 3 nm to about 13 nm, about 4 nm to about 12 nm, about 4 nm to about 8 nm, about 5 nm to about 11 nm, about 6 nm to about 10 nm, or about 7 nm to about 9 nm. When the quantum dot 10 meets the above average particle size range, the quantum dot 10 can not only exhibit characteristic behavior as a quantum dot, but also exhibit excellent or appropriate dispersibility in the composition for pattern formation. In some embodiments, by selecting one or more appropriate average particle sizes of the quantum dot 10 within the above range, the emission wavelength and / or semiconductor characteristics of the quantum dot 10 can be changed differently.

[0082] The shape of the quantum dot 10 is not particularly limited and may be any shape commonly used in the art. For example, the quantum dot 10 may be in the form of spherical, pyramidal, multi-armed or cubic nanoparticles, nanotubes, nanowires, nanofibers or nanoplates.

[0083] In one or more embodiments, the quantum dots 10 may have a spherical form.

[0084] The quantum dots 10 may be synthesized by various methods such as a wet chemical process, metal organic chemical vapor deposition (MOCVD), and / or a molecular beam epitaxy (MBE) process.

[0085] The first shell 10 b and the second shell 10 c of the quantum dot 10 may each serve as a protective layer for preventing or reducing chemical denaturation of the core 10 a and / or as a charging layer for imparting electrophoretic characteristics to the quantum dot 10 .

[0086] In one or more embodiments, the first shell 10 b and / or the second shell 10 c may further include a metal oxide or a non-metal oxide, a semiconductor compound, or a combination thereof.

[0087] Method for preparing quantum dots 10

[0088] Hereinafter, a method of preparing the quantum dot 10 according to the above-described embodiment will be described in more detail.

[0089] The method for preparing the quantum dot 10 according to the embodiment may include: preparing a first mixture in which a core 10a including a group III-V semiconductor compound alloyed with Ga is dispersed in an organic solvent at a concentration of 0.1 mM to 100 mM; forming a first shell 10b by reacting a second mixture, the second mixture being obtained by adding a first precursor including a group V element or a group VI element and a second precursor including a group II element or a group III element to the first mixture; and forming a second shell 10c by reacting a third mixture, the third mixture being obtained by adding a third precursor including a group V element or a group VI element and a fourth precursor including a group II element or a group III element to the reacted second mixture,

[0090] The atomic percentage (%) of Ga in the core 10a relative to the Group III elements other than Ga may be 25 atomic % to 30 atomic %, the first precursor and the third precursor may be different from each other, the first shell 10b may include a first compound which may be a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound, and the second shell 10c may include a second compound which may be a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound.

[0091] The synthesis method for the core 10a may be any suitable method in the art.

[0092] In one or more embodiments, the organic solvent may include trioctylamine, 1-nonadecene, 1-octadecene, 1-heptadecene, 1-hexadecene, 1-pentadecene, 1-tetradecene, or any combination thereof. For example, the organic solvent may include trioctylamine or 1-octadecene.

[0093] In one or more embodiments, the first mixture may further include a dispersant. The dispersant allows the core 10a to be uniformly dispersed in the organic solvent. The dispersant may include an anionic polymer material, a cationic polymer material, or a nonionic polymer material.

[0094] The amount of the dispersant may be about 10 to 50 parts by weight, for example, about 15 to about 30 parts by weight, relative to 100 parts by weight of the quantum dots 10. When the amount of the dispersant satisfies these ranges, the quantum dots 10 may be uniformly dispersed in the first mixture.

[0095] In the method of preparing quantum dots 10 according to one or more embodiments, by adjusting the concentration of cores 10a in the first mixture to 0.1 mM to 100 mM, the sphericity and weight absorption coefficient of the quantum dots 10 may be controlled or selected within a desired or appropriate range.

[0096] For example, when the concentration of the core 10a in the first mixture is about 0.1mM to about 1mM, the prepared quantum dot 10 may have a sphericity of about 0.9 or more. For another example, when the concentration of the core 10a in the first mixture is about 1mM to about 100mM, the prepared quantum dot 10 may have a sphericity of about 0.7 to about 0.9.

[0097] When the concentration of the core 10a in the first mixture satisfies these ranges, the prepared quantum dots 10 may have a carbon content of about 350 mL·g at a wavelength of 450 nm. -1 cm -1 About 1000 mL·g -1 cm -1 The weight absorption coefficient.

[0098] In one or more embodiments, the Group III-V semiconductor compound alloyed with Ga may include InGaP.

[0099] Figure 3A and Figure 3B TEM image of a quantum dot according to an embodiment having an InGaP / ZnSe / ZnS structure (having an InGaP core on which shells of ZnSe and ZnS are sequentially formed), wherein the InGaP core is concentrated at a concentration of 0.1 mM ( Figure 3A ) and 100 mM concentration ( Figure 3B ) is added to an organic solvent.

[0100] As Figure 3A and Figure 3B According to the results of TEM image analysis and calculation, the quantum dots prepared by adding 0.1 mM InGaP cores have an average sphericity of 0.9, and the quantum dots prepared by adding 100 mM InGaP cores have an average sphericity of 0.7. Accordingly, it can be confirmed that the quantum dots prepared by the preparation method according to the embodiment have a high sphericity of 0.7 or more.

[0101] In one or more embodiments, the first precursor may include trioctylphosphine-selenide (TOP-Se), tributylphosphine-selenide, triphenylphosphine-selenide, or any combination thereof. For example, the first precursor may include trioctylphosphine-selenide, but is not limited thereto.

[0102] In one or more embodiments, the third precursor may include trioctylphosphine-sulfide (TOP-S), tributylphosphine-sulfide, triphenylphosphine-sulfide, or any combination thereof. For example, the third precursor may include trioctylphosphine-sulfide, but is not limited thereto.

[0103] In one or more embodiments, the second precursor and the fourth precursor may each independently be or include: a compound including a Group II element. For example, the second precursor and the fourth precursor may each independently be or include zinc oleate, zinc acetate, zinc acetylacetonate, zinc stearate, or any combination thereof, but are not limited thereto.

[0104] In one or more embodiments, the method of preparing quantum dots 10 may further include adding a zinc precursor to the first mixture. For example, the zinc precursor may be or include zinc oleate, zinc acetate, zinc acetylacetonate, zinc stearate, or any combination thereof, but is not limited thereto.

[0105] The zinc precursor is not a constituent material of the core 10 a , but may adhere to the surface of the core 10 a to eliminate surface defects of the core 10 a , and thus minimize or reduce lattice defects of the first shell 10 b to be formed.

[0106] In one or more embodiments, in order to maintain the first mixture in a vacuum state, the method may further include adding a zinc precursor to the first mixture, and degassing at a temperature of 110° C. or higher.

[0107] The synthesis method for the first shell 10b may be any appropriate method in the art.

[0108] In one or more embodiments, the forming of the first shell 10b may be performed at a temperature ranging from about 240° C. to about 340° C. For example, the forming of the first shell 10b may be performed at a temperature ranging from about 260° C. to about 320° C.

[0109] The synthesis method for the second shell 10c may be any appropriate method in the art.

[0110] In one or more embodiments, the forming of the second shell 10c may be performed at a temperature ranging from about 240° C. to about 340° C. For example, the forming of the second shell 10c may be performed at a temperature ranging from about 260° C. to about 320° C.

[0111] As such, by forming the second shell 10 c , the quantum dot 10 having a core / shell structure in which the first shell 10 b and the second shell 10 c are sequentially formed on the surface of the core 10 a may be prepared.

[0112] The method of preparing the quantum dot 10 may further include, after the formation of the second shell 10c, purifying the synthesized quantum dot 10. The purification may be performed using chloroform, ethanol, acetone, or any combination thereof.

[0113] Optical components

[0114] According to another aspect, an optical component including quantum dots 10 is provided.

[0115] The optical member may be a color conversion member. Since the color conversion member includes the quantum dots 10 having excellent or appropriate light conversion efficiency as described above, the color conversion member may have excellent or appropriate light conversion efficiency.

[0116] The color conversion member may include a substrate and a pattern layer formed on the substrate.

[0117] The substrate itself may be or serve as a substrate for a color conversion member, or may be a region of a device (e.g., a display device) on which a color conversion member is disposed. The substrate may be glass, silicon (Si), silicon oxide (SiO x ) and / or a polymer substrate. The polymer substrate may be polyethersulfone (PES) and / or polycarbonate (PC).

[0118] The pattern layer may be or include quantum dots 10 in the form of a thin film. For example, the pattern layer may be or include quantum dots 10 in the form of a thin film.

[0119] The color conversion member including the substrate and the pattern layers may further include a partition wall or a black matrix formed between each pattern layer. In some embodiments, the color conversion member may further include a color filter to further improve light conversion efficiency.

[0120] The color conversion member may include a red pattern layer capable of emitting red light, a green pattern layer capable of emitting green light, a blue pattern layer capable of emitting blue light, or any combination thereof. The red pattern layer, the green pattern layer, and / or the blue pattern layer may be implemented by controlling the components, composition, and / or structure of the quantum dots 10.

[0121] For example, the quantum dots 10 in the color conversion member may absorb the first light and emit the second light different from the first light. For example, the quantum dots 10 may absorb blue light and emit visible light other than blue light, for example, visible light with a maximum emission wavelength of 495nm to 750nm. Accordingly, the color conversion member including the quantum dots 10 may be designed to absorb blue light and emit wavelengths of various color ranges.

[0122] For another example, the quantum dots 10 in the color conversion member may absorb blue light and emit green light having a maximum emission wavelength of 495 nm to 570 nm. Therefore, the color conversion member including the quantum dots 10 may implement green light having high brightness and high color purity.

[0123] Electronic Devices

[0124] The quantum dot 10 may be included in various electronic devices. For example, the electronic device including the quantum dot may be a light emitting device and / or an authentication device.

[0125] The electronic device may further include a light source. The quantum dot 10 may be arranged in a light path of light emitted from the light source.

[0126] In other embodiments, an electronic device may include a light source and a color conversion member, wherein the color conversion member may include quantum dots 10. The color conversion member may be disposed in (eg, intersect) an optical path of light emitted from the light source.

[0127] In this case, the fact that the color conversion member is located in at least one traveling direction of light emitted from the light source does not exclude the case where other elements are further included between the quantum dot 10 or the color conversion member and the light source.

[0128] For example, a polarizing plate, a liquid crystal layer, a light guide plate, a diffusion plate, a prism sheet, a microlens sheet, a brightness enhancement sheet, a reflective film, a color filter, or any combination thereof may be disposed between the light source and the quantum dots 10 or between the light source and the color conversion member.

[0129] As another example, a polarizing plate, a liquid crystal layer, a light guide plate, a diffusion plate, a prism sheet, a microlens sheet, a brightness enhancement sheet, a reflective film, a color filter, or any combination thereof may be disposed on the quantum dot 10 or the color conversion member.

[0130] The light source may be a backlight unit (BLU) utilized in a liquid crystal display (LCD), a fluorescent lamp, a light emitting diode (LED), an organic light emitting device (OLED), or a quantum dot light emitting device, but is not limited thereto.

[0131] As described above, light emitted from the light source may undergo light conversion while passing through the quantum dot 10. For example, the quantum dot 10 may absorb the first light emitted from the light source and emit visible light different from the first light. For example, the quantum dot 10 may absorb the blue light emitted from the light source and emit visible light having a maximum emission wavelength of 495 nm to 750 nm. Accordingly, the quantum dot 10 or a color conversion member including the quantum dot 10 may be designed to absorb the blue light emitted from the light source and emit wavelengths of various color ranges.

[0132] For example, the quantum dot 10 can absorb blue light emitted from the light source and emit green light with a maximum emission wavelength of 495nm to 570nm. For another example, the quantum dot 10 can absorb blue light emitted from the light source and emit red light with a maximum emission wavelength of 630nm to 750nm. Accordingly, the quantum dot 10 or a color conversion member including the quantum dot 10 can absorb blue light emitted from the light source and emit green light or red light with high brightness and high color purity.

[0133] Hereinafter, embodiments of the quantum dot 10 and a method of preparing the same will be described in more detail through the following examples and / or comparative examples.

[0134] Example

[0135] Preparation Example 1

[0136] Preparation of InGaP core

[0137] In a microwave reaction tube, an indium precursor and a gallium precursor of 80 wt% to 200 wt% relative to the indium precursor are mixed, and tris(trimethylsilyl)phosphine diluted to 20 wt% is added thereto, and microwave irradiation is performed for 7 minutes. The reaction temperature is 280°C. After the reaction product is cooled to room temperature, the reaction product is purified twice by centrifugation with 5 mL of toluene and 30 mL of acetone to obtain an InGaP core with 26 atomic % of Ga / In. The resulting InGaP core is dispersed in toluene.

[0138] Growth of ZnSe shell (first shell) / ZnS shell (second shell)

[0139] InGaP crystals dispersed in toluene were added to a reaction flask containing 80 mL of trioctylamine at a concentration of 0.5 mM, and 4.9 mmol of zinc oleate was added thereto and then dispersed by ultrasound to prepare a first mixture. Subsequently, the first mixture was degassed at 110° C. and kept in a vacuum state.

[0140] In a nitrogen atmosphere, 4.5 mmol of TOP-Se and 18.0 mmol of zinc oleate were added to a reaction flask to prepare a second mixture. The reaction flask was then heated to 320°C and reacted for 60 minutes. Subsequently, 22.4 mmol of TOP-S and 9.6 mmol of zinc oleate were added to the reaction flask to prepare a third mixture. The reaction flask was then heated to 320°C and reacted for 90 minutes.

[0141] After the reaction was terminated, the reaction flask was cooled to room temperature. Subsequently, the crude product was purified once with 5 mL of toluene and 30 mL of ethanol by centrifugation to obtain a green quantum dot composition. The prepared quantum dots had an InGaP / ZnSe / ZnS structure.

[0142] Preparation Examples 2 and 3

[0143] Quantum dot compositions were prepared in substantially the same manner as in Preparation Example 1, except that the atomic percentages of Ga / In in the InGaP cores of Preparation Examples 2 and 3 were 45 atomic % and 55 atomic %, respectively.

[0144] Preparation Example 4

[0145] Preparation of InGaP core

[0146] After growing InGaP cores having Ga / In of 26 atomic % in substantially the same manner as in Preparation Example 1, the reaction solution was rapidly cooled to room temperature, and acetone was added thereto and centrifuged. The resulting precipitate was dispersed in toluene.

[0147] Growth of ZnSe shell (first shell) / ZnS shell (second shell)

[0148] InGaP crystals dispersed in toluene were added to a reaction flask containing 80 mL of trioctylamine at a concentration of 0.1 mM, and 4.8 mmol of zinc oleate was added thereto and then dispersed by ultrasound to prepare a first mixture. Subsequently, the first mixture was degassed at 110° C. and kept in a vacuum state.

[0149] In a nitrogen atmosphere, 4.5 mmol of TOP-Se and 18.0 mmol of zinc oleate were added to a reaction flask to prepare a second mixture. The reaction flask was then heated to 320°C and reacted for 60 minutes. Subsequently, 22.4 mmol of TOP-S and 9.6 mmol of zinc oleate were added to the reaction flask to prepare a third mixture. The reaction flask was then heated to 320°C and reacted for 90 minutes.

[0150] After the reaction was terminated, the reaction flask was cooled to room temperature. Subsequently, the crude product was purified once with 5 mL of toluene and 30 mL of ethanol by centrifugation to obtain a green quantum dot composition. The prepared quantum dots had an InGaP / ZnSe / ZnS structure.

[0151] Preparation Examples 5 to 8

[0152] Quantum dot compositions were prepared in substantially the same manner as in Preparation Example 4, except that InGaP crystals dispersed in toluene were added at concentrations of 1 mM, 10 mM, 50 mM, and 100 mM, respectively, to prepare first mixtures for Preparation Examples 5 to 8.

[0153] Preparation Examples 9 to 13

[0154] A quantum dot composition having an atomic percentage of Se / In and an atomic percentage of S / In as shown in Table 1 was prepared in substantially the same manner as in Preparation Example 1, except that InGaP crystals (Ga / In = 26 atomic %) dispersed in toluene were added in an amount as shown in Table 1, wherein the atomic percentage of Se / In and the atomic percentage of S / In are expressed as percentages based on (e.g., relative to) 50 atomic % Se / In and 50 atomic % S / In, respectively.

[0155] Table 1

[0156]

[0157] Evaluation Example 1: Experiment on the change of shell characteristics relative to the amount of Ga element in the InGaP core

[0158] The UV-Vis absorption spectra of InGaP cores (having a core diameter of 2.5 nm) with 26 atomic %, 45 atomic % or 55 atomic % of Ga / In were analyzed to obtain the respective first exciton absorption peak wavelengths.

[0159] Table 2

[0160]

[0161]

[0162] The valley-to-peak ratio (V to P) was obtained from the absorption spectra of InGaP cores (having a core diameter of 2.5 nm) with 26 atomic %, 45 atomic % or 55 atomic % Ga / In, and the full width at half maximum (FWHM) was obtained from the emission spectra of the InGaP cores. The line graphs of the valley-to-peak ratio (V to P) and FWHM of the InGaP cores with respect to the Ga / In atomic percentage are shown in Figure 4 middle.

[0163] refer to Figure 4 The InGaP core with a Ga / In atomic percentage of 26% according to the embodiment of the present disclosure has a valley-to-peak ratio of about 0.75 and a very narrow FWHM of about 25 nm. Therefore, it is found that the InGaP core of Preparation Example 1 has a dense particle size distribution and energy band distribution, and has improved color purity.

[0164] The luminescence spectra of the quantum dot compositions prepared in Preparation Examples 1 to 3 were measured to obtain quantum efficiency, PL maximum emission wavelength and FWHM. The results are shown in Table 3.

[0165] Table 3

[0166]

[0167] It is found from Table 3 that the quantum dot composition of Preparation Example 1 exhibits higher quantum efficiency than the quantum dot compositions of Preparation Examples 2 and 3, and has a PL maximum emission wavelength of 530 nm and a relatively narrow FWHM.

[0168] Evaluation Example 2: Measurement of Gravimetric Absorption Coefficient Relative to InGaP Core Concentration

[0169] The absorbance of the quantum dot compositions prepared in Preparation Examples 4 to 8 was measured using an Agilent Cary 300Bio UV-Vis spectrophotometer having a cuvette with an optical path length of 10 mm and filled with a 10 ppm solution, and the weight absorption coefficient (mL·g -1 cm -1). The results are shown in Table 4.

[0170] Table 4

[0171]

[0172] Referring to Table 4, it was found that the quantum dot compositions prepared in Preparation Examples 4 to 8 exhibited a 350 mL·g -1 cm -1 or greater weight absorption coefficient.

[0173] The absorbance graphs of the quantum dot compositions (0.1 mM and 100 mM) prepared in Preparation Examples 4 and 8 are shown in Figure 5 In. From Figure 5 It was found that as the concentration of InGaP crystals added to make quantum dots increased, the absorbance increased and therefore the gravimetric absorption coefficient increased.

[0174] Evaluation Example 3: Measurement of weight absorption coefficient relative to Se / In and S / In atomic percentage

[0175] The weight absorption coefficients of the quantum dot compositions prepared in Preparation Examples 9 to 13 were calculated in substantially the same manner as in Evaluation Example 2. The results are shown in Table 5.

[0176] In Table 5, the atomic percentage of Se / In and the atomic percentage of S / In are expressed as percentages based on (eg, relative to) 50 atomic % of Se / In and 50 atomic % of S / In, respectively.

[0177] Table 5

[0178]

[0179] Referring to Table 5, it was found that the quantum dot compositions prepared in Preparation Examples 9 to 13 exhibited a 350 mL·g -1 cm -1 or greater high weight absorption coefficient.

[0180] As described above, the quantum dots according to one or more embodiments of the present disclosure have high sphericity and high weight absorption coefficient, and therefore, when a small content (amount) of quantum dots is used in an optical member, high luminous efficiency can be obtained, and the quantum dots can be economical. Electronic devices including quantum dots can achieve excellent or appropriate color reproducibility.

[0181] As used herein, the terms "substantially," "about," and similar terms are used as terms of approximation, and not as terms of degree, and are intended to take into account the inherent deviations of measured or calculated values ​​that one of ordinary skill in the art would recognize. Taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system), "about" or "approximately" as used herein include the stated value and mean within the range of acceptable deviations of the particular value as determined by one of ordinary skill in the art. For example, "about" can mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0182] Any numerical range set forth herein is intended to include all sub-ranges of the same numerical precision falling within the range set forth. For example, the range of "1.0 to 10.0" is intended to include between the minimum value of 1.0 set forth and the maximum value of 10.0 set forth (and including 1.0 and 10.0), that is, all sub-ranges with a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limit set forth herein is intended to include all lower numerical limits falling therein, and any minimum numerical limit set forth in this specification is intended to include all higher numerical limits falling therein. Accordingly, the applicant reserves the right to modify this specification, including the claims, to explicitly set forth any sub-range falling within the range explicitly set forth herein.

[0183] It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for limiting purposes. The description of the features or aspects in each embodiment should generally be considered to be applicable to other similar features or aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, it will be understood by those of ordinary skill in the art that various appropriate changes may be made in form and detail without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A quantum dot, comprising: A core comprising a Group III-V semiconductor compound alloyed with gallium; a first shell surrounding the core; as well as a second shell surrounding the first shell, wherein the first shell comprises a first compound, the first compound comprises a Group II-VI semiconductor compound, a Group III-V semiconductor compound or a Group III-VI semiconductor compound, the second shell includes a second compound, the second compound includes a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound, and the first compound and the second compound are different from each other, The atomic percentage of gallium in the core relative to the Group III element other than Ga in the core is 25 atomic % to 30 atomic %, The atomic percentage of the Group V element or the Group VI element in the first shell relative to the Group III element in the core is 5 atomic % to 50 atomic %, and The atomic percentage of the Group V element or the Group VI element in the second shell relative to the Group III element in the core is 5 atomic % to 50 atomic %. 2 . The quantum dot of claim 1 , wherein the Group III-V semiconductor compound alloyed with gallium in the core comprises InGaP.

3. The quantum dot of claim 1, wherein the II-VI semiconductor compounds in the first shell and the second shell include ZnSe, ZnS, ZnTe, ZnO, ZnMgSe, ZnMgS or a combination thereof, the III-V semiconductor compounds in the first shell and the second shell include GaP, GaAs, GaSb, InAs, InSb, AlP, AlAs, AlSb or a combination thereof, and the III-VI semiconductor compounds in the first shell and the second shell include GaSe, GaTe or a combination thereof.

4. The quantum dot of claim 1, wherein the first shell and the second shell each independently comprise a different Group II-VI semiconductor compound, The atomic percentage of the Group VI element in the first shell relative to the Group III element in the core is 10 atomic % to 15 atomic %, and The atomic percentage of the Group VI element in the second shell relative to the Group III element in the core is 10 atomic % to 15 atomic %.

5. The quantum dots according to claim 1, wherein the weight absorption coefficient of the quantum dots at a wavelength of 450 nm is 350 mL·g -1 cm -1 Up to 1000mL·g -1 cm -1 . The quantum dot according to claim 1 , wherein the quantum dot has a quantum efficiency of 90% or greater. The quantum dot according to claim 1 , wherein the full width at half maximum of the photoluminescence spectrum of the quantum dot is 40 nm or less. The quantum dots according to claim 1 , wherein the quantum dots have a sphericity of 0.7 to 0.

9.

9. A method for preparing a quantum dot according to any one of claims 1 to 8, the method comprising: preparing a first mixture in which a core including a Group III-V semiconductor compound alloyed with gallium is dispersed in an organic solvent at a concentration of 0.1 mM to 100 mM; forming a first shell by reacting a second mixture obtained by adding a first precursor including a Group V element or a Group VI element and a second precursor including a Group II element or a Group III element to the first mixture; as well as forming a second shell by reacting a third mixture obtained by adding a third precursor including a Group V element or a Group VI element and a fourth precursor including a Group II element or a Group III element to the reacted second mixture, wherein the atomic percentage of gallium in the core relative to the atomic percentage of the Group III element other than Ga in the core is 25 atomic % to 30 atomic %, The first precursor and the third precursor are different from each other, The first shell includes a first compound, the first compound includes a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound; and the second shell includes a second compound, the second compound includes a Group II-VI semiconductor compound, a Group III-V semiconductor compound, or a Group III-VI semiconductor compound. 10 . An optical member comprising the quantum dot according to claim 1 or the quantum dot prepared by the method according to claim 9 .

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