Quantum dot and photoelectric device comprising same

Abstract

The quantum dot comprises a core, a first layer and a second layer which are sequentially arranged in the radius direction from inside to outside, the first layer wraps the core, the second layer wraps the first layer, the band gap of the first layer is smaller than the band gap of the core, the band gap of the first layer is smaller than the band gap of the second layer, and the band gap of the second layer is smaller than the band gap of the core. The quantum dot has a well-type structure, is favorable for increasing an exciton confinement effect, constraining excitons to be far away from the surface and preventing the excitons from being captured by surface defects, improves the fluorescence quantum efficiency of the quantum dot, and is favorable for improving the device efficiency of a photoelectric device by applying the quantum dot to the photoelectric device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optoelectronic materials, in particular to a quantum dot and an optoelectronic device containing the quantum dot. BACKGROUND

[0002] Quantum dots (QDs) are also called semiconductor nanocrystals, which are nanocrystals with a radius less than or close to the Bohr radius of excitons, and the average particle size is usually between 1nm and 30nm. Quantum dots have unique fluorescence nanometer effect, and the luminescence wavelength of quantum dots can be regulated by changing their size and composition. Quantum dots have the advantages of narrow half-peak width of luminescence spectrum, high color purity, good light stability, wide excitation spectrum, and controllable emission spectrum, and have wide application prospects in photovoltaic power generation, optoelectronic display, biological probes and other technical fields.

[0003] With more and more in-depth research and development of quantum dots, the existing types of quantum dots are gradually difficult to meet the needs of more and more application scenarios, therefore, it is urgent to develop new types of quantum dots to expand the types of quantum dots. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a quantum dot and an optoelectronic device containing the quantum dot.

[0005] The technical scheme of the present application is as follows:

[0006] In a first aspect, the present application provides a quantum dot, which comprises, in the direction of radius from inside to outside, a core, a first layer and a second layer arranged in sequence, the first layer coats the core, and the second layer coats the first layer; the band gap of the first layer is smaller than the band gap of the core, and the band gap of the first layer is smaller than the band gap of the second layer.

[0007] In a second aspect, the present application provides an optoelectronic device, which comprises:

[0008] a cathode and an anode arranged oppositely; and

[0009] a plurality of functional layers arranged between the anode and the cathode;

[0010] Among them, the material of at least one functional layer in the plurality of functional layers comprises the quantum dot as described in the first aspect.

[0011] The present application provides a quantum dot and an optoelectronic device containing the quantum dot, which has the following technical effects:

[0012] The quantum dot has a well structure, which is conducive to increasing the exciton confinement effect, binding excitons away from the surface, avoiding the capture of excitons by surface defects, and improving the fluorescence quantum efficiency of the quantum dot. BRIEF DESCRIPTION OF DRAWINGS

[0013] The technical solutions and other advantages of the present application will be apparent from the following detailed description of the application, taken in conjunction with the accompanying drawings.

[0014] Figure 1 A structure diagram of a first quantum dot provided by an embodiment of the present application.

[0015] Figure 2 A structure diagram of a second quantum dot provided by an embodiment of the present application.

[0016] Figure 3 A structure diagram of a third quantum dot provided by an embodiment of the present application.

[0017] Figure 4 A structure diagram of a photoelectric device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0018] The technical solutions and other advantages of the present application will be apparent from the following detailed description of the application, taken in conjunction with the accompanying drawings.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Any method and material similar or equivalent to those described herein can be used in the present application. The preferred methods and materials described herein are illustrative only and not intended to be limiting. Equivalent steps and procedures can be employed as long as they achieve the same results.

[0020] It should be noted that the description of the following embodiments is not intended to limit the preferred order of the embodiments. Each embodiment of the present application can exist in a range of forms; it should be understood that the description of a range of forms is merely for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single values within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated in this document, it refers to any cited number (fraction or integer) within the indicated range.

[0021] In the description of the present application, the term "comprising" means "including but not limited to".

[0022] The term "at least one" means one or more, "multiple" means two or more. The terms "at least one of," "one or more of," or "one or more," means any combination of one or more of the items, including single items or combinations of multiple items. For example, "at least one of a, b, or c" or "one or more of a, b, or c" can be interpreted as a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, where a, b, and c can be single items or multiple items.

[0023] The term "and / or" includes any combination of associated items, including any two or more of the associated items, any of the associated items, or all of the associated items. For example, "A and / or B" includes A, B, and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (i.e., the technical solution connected by "logical or"), and includes any and all combinations of A, B, C, and D, that is, includes any two or any three combinations of A, B, C, and D, and includes the four-item combination of A, B, C, and D (i.e., the technical solution connected by "logical and").

[0024] In the present application, "A layer is formed on one side of B layer", "A layer is formed on the side of B layer away from C layer", or the like can mean that A layer is directly formed on one side of B layer or on the side of B layer away from C layer, that is, A layer is in direct contact with B layer, or can mean that A layer is indirectly formed on one side of B layer or on the side of B layer away from C layer, that is, other spacer structure layers can be further formed between A layer and B layer. Similarly, "A layer is disposed on one side of B layer", "A layer is disposed on the side of B layer away from C layer", or "A layer is disposed between B layer and C layer" can mean that A layer is in direct contact with B layer, or can mean that other spacer structure layers are further provided between A layer and B layer.

[0025] The term "particle size" refers to the diameter of a nanoparticle.

[0026] The term "conduction band" refers to the energy level of excited electrons in a crystal in the excited state. In this application, the conduction band is referenced to the vacuum energy level of 0, and the "conduction band bottom" is the lowest energy level of the conduction band.

[0027] The term "valence band" refers to the energy level of unexcited electrons in a crystal in its ground state. In this application, the valence band is referenced with the vacuum energy level being 0, and "valence band top" refers to the highest energy level of the valence band.

[0028] The term "gap" refers to the difference between the bottom of the price band and the top of the price band.

[0029] In this application, the difference between A and B refers to the value obtained by subtracting B from A, where A is the minuend and B is the subtrahend. Taking "the difference between the valence band peak of the core and the valence band peak of the first layer is not greater than -0.2 eV" as an example, the valence band peak of the core is the minuend, and the valence band peak of the first layer is the subtrahend. The value obtained by subtracting the valence band peak of the first layer from the valence band peak of the core is not greater than -0.2 eV. The difference between the valence band peak of the core and the valence band peak of the first layer can be expressed as ΔE. V,核-第一层 .

[0030] This application provides a quantum dot, such as... Figures 1 to 3 As shown, in the radial direction from the inside to the outside, the quantum dot 11 includes a core 111, a first layer 112 and a second layer 113 arranged sequentially. The first layer 112 covers the core 111, and the second layer 113 covers the first layer 112. The band gap of the first layer 112 is smaller than the band gap of the core 111, and the band gap of the first layer 112 is smaller than that of the second layer 113.

[0031] In the quantum dot 11 of this application embodiment, the quantum dot 11 has a trap structure, which is beneficial to increase the exciton confinement effect, trap the excitons away from the surface, avoid the excitons being captured by surface defects, and improve the fluorescence quantum efficiency of the quantum dot.

[0032] In order to reduce the difficulty of carrier injection, in some embodiments of this application, the band gap of the second layer 113 is not greater than the band gap of the core 111.

[0033] In some embodiments of this application, quantum dot 11 is a light-emitting quantum dot, for example, quantum dot 11 is a blue quantum dot.

[0034] To improve the recombination luminescence efficiency of injected electrons and holes in the trap core, in some embodiments of this application, the difference between the valence band peak of core 111 and the valence band peak of the first layer 112 is no greater than -0.2 eV, for example, no greater than -0.22 eV, no greater than -0.25 eV, or no greater than -0.3 eV. In at least one embodiment of this application, the difference between the valence band peak of core 111 and the valence band peak of the first layer 112 is no less than -0.8 eV and no greater than -0.2 eV; the difference between the valence band peak of the first layer 112 and the valence band peak of the second layer 113... The difference between them is not less than 0.2eV, for example, not less than 0.22eV, not less than 0.25eV, not less than 0.28eV or not less than 0.3eV. The difference between the conduction band bottom of the first layer 112 and the conduction band bottom of the second layer 113 is not greater than -0.2eV, for example, not greater than -0.22eV, not greater than -0.25eV or not greater than -0.3eV. In at least one embodiment of this application, the difference between the valence band top of the first layer 112 and the valence band top of the second layer 113 is not less than 0.2eV and not greater than 0.8eV.

[0035] In order to achieve an emission wavelength of quantum dot 11 of no more than 475 nm, in some embodiments of this application, the average particle size of core 111 is 2 nm to 8 nm, for example, 2 nm, 4 nm, 6 nm, 8 nm or any two of the aforementioned values; and / or, the average thickness of the first layer 112 is 1 nm to 3 nm, for example, 1 nm, 2 nm, 3 nm or any two of the aforementioned values; and / or, the average thickness of the second layer 113 is 1 nm to 4 nm, for example, 1 nm, 2 nm, 3 nm, 4 nm or any two of the aforementioned values; and / or, the average particle size of quantum dot core 11 is 4 nm to 15 nm, for example, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 15 nm or any two of the aforementioned values.

[0036] For the quantum dot core 11, the material of core 111 is a first compound, the material of the first layer 112 is a second compound, and the material of the second layer 113 is a third compound.

[0037] In some embodiments of this application, see further reference. Figures 1 to 3The quantum dot 11 also includes a first interface fusion layer 114 located between the core 111 and the first layer 112. The material of the first interface fusion layer 114 includes a first compound and a second compound. Along the radial direction from the core 111 to the first layer 112, the molar percentage of the first compound gradually decreases, and the molar percentage of the second compound gradually increases to form a gradient energy level, which is beneficial to further reduce the difficulty of carrier injection. The thickness of the first interface fusion layer 114 is, for example, 0.2 nm to 2 nm, with examples being 0.2 nm, 0.5 nm, 0.8 nm, 1 nm, 1.5 nm, 2 nm, or any two of the aforementioned values. It should be noted that the first interface fusion layer 114 mainly originates from the exchange of interface atoms. At a specific temperature, a first layer 112 with different compositions is grown on the surface of the core 111. Atom exchange occurs at the interface between the core 111 and the first layer 112, thereby forming the first interface fusion layer 114.

[0038] In some embodiments of this application, see further reference. Figures 1 to 3 The quantum dot 11 also includes a second interface fusion layer 115 located between the first layer 112 and the second layer 113. The second interface fusion layer 115 comprises a second compound and a third compound. Along the radial direction from the first layer 112 to the second layer 113, the molar percentage of the second compound gradually decreases, while the molar percentage of the third compound gradually increases, to form a gradient energy level, which is beneficial for further reducing the difficulty of carrier injection. The thickness of the second interface fusion layer 115 is, for example, 0.2 nm to 2 nm, with examples being 0.2 nm, 0.5 nm, 0.8 nm, 1 nm, 1.5 nm, 2 nm, or any two of the aforementioned values. It should be noted that the second interface fusion layer 115 mainly originates from the exchange of interface atoms. At a specific temperature, a second layer 113 with a different composition is grown on the surface of the first layer 112. Atom exchange occurs at the interface between the first layer 112 and the second layer 113, thereby forming the second interface fusion layer 115.

[0039] In some embodiments of this application, the materials of core 111, the first layer 112, and the second layer 113 are independently selected from one or more of group II-VI compounds, group III-V compounds, group III-VI compounds, group IV-VI compounds, and group I-III-VI compounds. Among them, group II-VI compounds include, but are not limited to, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, CdZnSeS, and CdZnSeT. e, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; and / or, III-V compounds including but not limited to GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InP One or more of As, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; and / or, group III-VI compounds including but not limited to one or more of In2S3, In2Se3, InGaS3, and InGaSe3; and / or, group IV-VI compounds including but not limited to SnS, SnSe, One or more of SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; and / or, group I-III-VI compounds, including but not limited to one or more of AgInS, AgInS2, CuInS, CuInS2, AgGaS2, CuGaS2, CuGaO2, AgGaO2, AgAlO2, AgInGaS2, and CuInGaS2.

[0040] In some embodiments of this application, the core 111 is made of ZnA, the first layer 112 is made of CdM, and the second layer 113 is made of Cd. x Zn (1-x) N, where Zn is zinc, Cd is cadmium, A, M and N are independently selected from Se or S, 0.2≤x≤0.5, where x is, for example, 0.2, 0.3, 0.4, 0.5 or any two of the aforementioned values.

[0041] To further improve the exciton lifetime of quantum dots and reduce the probability of nonradiative Auger recombination, further reference is made to some embodiments of this application. Figures 1 to 3 The quantum dot also includes one or more of the following: a third layer 116 with a hole confinement structure, a fourth layer 117 with an electron confinement structure, and a fifth layer 118 with a Type I confinement structure.

[0042] In the radial direction from the inside out, taking the core 111 to the second layer 113 as a whole structure (including the core 111, the first interface fusion layer 114, the first layer 112, the second interface fusion layer 115, and the second layer 113), the absolute value of the difference between the valence band top of the third layer 116 and the valence band top of the whole structure is greater than 0 eV and not less than 0.2 eV, for example, it can be 0.1 eV, 0.15 eV, 0.18 eV, or any two of the aforementioned values, and the absolute value of the difference between the conduction band bottom of the whole structure and the conduction band bottom of the third layer 116 is not less than 0.2 eV and not greater than 0.8 eV, for example, it can be 0.2 eV, 0.3 eV, 0.4 eV, 0.5 eV, 0.6 eV, 0.7 eV, 0.8 eV, or any two of the aforementioned values.

[0043] In some embodiments of this application, the difference between the valence band top of the third layer 116 and the valence band top of the overall structure is not less than -0.2 eV and less than 0 eV, and the difference between the conduction band bottom of the overall structure and the conduction band bottom of the third layer 116 is not less than 0.2 eV and not greater than 0.8 eV.

[0044] In the radial direction from the inside out, taking the core 111 to the second layer 113 as a whole structure (including the core 111, the first interface fusion layer 114, the first layer 112, the second interface fusion layer 115, and the second layer 113), for the fourth layer 117 with an electron confinement structure, the absolute value of the difference between the valence band top of the fourth layer 117 and the valence band top of the whole structure is not less than 0.2 eV and not greater than 0.8 eV, for example, it can be 0.2 eV, 0.3 eV, 0.4 eV, 0.5 eV, 0.6 eV, 0.7 eV, 0.8 eV, or any two of the aforementioned values; and the absolute value of the difference between the conduction band bottom of the whole structure and the conduction band bottom of the fourth layer 117 is greater than 0 eV and not greater than 0.2 eV, for example, it can be 0.1 eV, 0.15 eV, 0.18 eV, or any two of the aforementioned values.

[0045] In some embodiments of this application, the difference between the valence band top of the fourth layer 117 and the valence band top of the overall structure is not less than -0.8 eV and not greater than -0.2 eV, and the difference between the conduction band bottom of the overall structure and the conduction band bottom of the fourth layer 117 is greater than 0 eV and not greater than 0.2 eV.

[0046] In the radial direction from the inside out, taking the core 111 to the second layer 113 as a whole structure (including the core 111, the first interface fusion layer 114, the first layer 112, the second interface fusion layer 115, and the second layer 113), for those with Type The absolute value of the difference between the fifth layer 118 of the type I confined structure and the valence band top of the overall structure is not less than 0.2 eV and not greater than 0.8 eV, for example, it can be 0.2 eV, 0.3 eV, 0.4 eV, 0.5 eV, 0.6 eV, 0.7 eV, 0.8 eV or any two of the aforementioned values; and the absolute value of the difference between the conduction band bottom of the overall structure and the conduction band bottom of the fifth layer 118 is not less than 0.2 eV and not greater than 0.8 eV, for example, it can be 0.2 eV, 0.3 eV, 0.4 eV, 0.5 eV, 0.6 eV, 0.7 eV, 0.8 eV or any two of the aforementioned values.

[0047] In some embodiments of this application, the difference between the valence band top of the fifth layer 118 and the valence band top of the overall structure is not less than -0.8 eV and not greater than -0.2 eV, and the difference between the conduction band bottom of the overall structure and the conduction band bottom of the fifth layer 118 is not less than 0.2 eV and not greater than 0.8 eV.

[0048] It should be noted that the valence band top and conduction band bottom of each layer or the overall structure can be obtained by ultraviolet photoelectron spectroscopy (UPS).

[0049] To further improve the fluorescence quantum efficiency and stability of quantum dot 11, further reference is made to some embodiments of this application. Figure 1 The quantum dot 11 includes the third layer 116 and the fifth layer 118, with the fifth layer 118 located on the outermost layer, increasing the delocalization range of holes and helping to improve the hole propagation speed. It is understood that in this embodiment, in the radial direction from the inside out, the quantum dot 11 includes a core 111, a first layer 112, a second layer 113, a third layer 116, and a fifth layer 118 arranged sequentially. Based on the atomic exchange phenomenon occurring at the interface, a third interface fusion layer may be present between the third layer 116 and the second layer 113, and a fourth interface fusion layer may be present between the third layer 116 and the fifth layer 118.

[0050] To further improve the fluorescence quantum efficiency and stability of quantum dot 11, further reference is made to some other embodiments of this application. Figure 2 The quantum dot 11 includes a fourth layer 117 and a fifth layer 118, with the fifth layer 118 located on the outermost layer, increasing the delocalization range of electrons and helping to improve electron transport speed. It is understood that in this embodiment, in the radial direction from the inside out, the quantum dot 11 includes a core 111, a first layer 112, a second layer 113, a fourth layer 117, and a fifth layer 118 arranged sequentially. Based on the atomic exchange phenomenon occurring at the interface, a fifth interface fusion layer may be present between the fourth layer 117 and the second layer 113, and a sixth interface fusion layer may be present between the fourth layer 117 and the fifth layer 118.

[0051] To further improve the fluorescence quantum efficiency and stability of quantum dot 11, in some embodiments of this application, quantum dot 11 includes a third, fourth, and fifth layer, with the fourth layer located between the third and fifth layers, or the third layer located between the fourth and fifth layers. By fully delocalizing holes and electrons, the overlap between the wave functions of holes and electrons is reduced, thereby improving the exciton lifetime of the quantum dot and reducing the risk of quenching of surface defect states, thus improving the radiative recombination efficiency. It is understood that, in the radial direction from the inside out, [further details are needed]. Figure 3The quantum dot may include a core 111, a first layer 112, a second layer 113, a third layer 116, a fourth layer 117, and a fifth layer 118 arranged sequentially. Based on the atomic exchange phenomenon that occurs at the interface, there may be a third interface fusion layer between the third layer 116 and the second layer 113, a seventh interface fusion layer between the third layer 116 and the fourth layer 117, and a sixth interface fusion layer between the fourth layer 117 and the fifth layer 118. Alternatively, in the radial direction from the inside out, the quantum dot may include a core 111, a first layer 112, a second layer 113, a fourth layer 117, a third layer 116, and a fifth layer 118 arranged sequentially. Based on the atomic exchange phenomenon that occurs at the interface, there may be a fifth interface fusion layer between the fourth layer 117 and the second layer 113, an eighth interface fusion layer between the fourth layer 117 and the third layer 116, and a fourth interface fusion layer between the third layer 116 and the fifth layer 118.

[0052] In some embodiments of this application, quantum dot 11 is used as the light-emitting material of quantum dot light-emitting diode. Since quantum dot light-emitting diodes have the problem that the electron injection level is much greater than the hole injection level, especially blue quantum dot light-emitting diodes, the shell of the quantum dot is composed of a third layer, a fourth layer and a fifth layer. The third layer is located between the fourth layer and the fifth layer, which has a greater influence on confining the delocalization of the electron wave function and can promote the balance of electron-hole transport.

[0053] In some embodiments of this application, the material of the third layer is Cd. y1 Zn (1-y1) Se, where 0 ≤ y1 < 1, the average thickness of the third layer is, for example, 1 nm to 3 nm; and / or, the material of the fourth layer is Cd. y2 Zn (1-y2) S, where 0 < y2 ≤ 1, the average thickness of the fourth layer is, for example, 1 nm to 3 nm; and / or, the material of the fifth layer is ZnS, the average thickness of the fifth layer is, for example, 0.5 nm to 2 nm; and / or, the average thickness of the quantum dot shell is 2.5 nm to 8 nm, for example, 2.5 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm or any two of the aforementioned values.

[0054] In some embodiments of this application, the general structural formula of the quantum dot is any of the following:

[0055] (A1)ZnA / CdM / Cd x Zn (1-x) N / Cd y1 Zn (1-y1) Se / Cd y2 Zn (1-y2) S / ZnS;

[0056] (A2)ZnA / CdM / Cdx Zn (1-x) N / Cd y1 Zn (1-y1) Se / ZnS;

[0057] (A3)ZnA / CdM / Cd x Zn (1-x) N / Cd y2 Zn (1-y2) S / ZnS;

[0058] Where A, M, and N are independently selected from elements Se or S, 0.2≤x≤0.5, 0≤y1<1, 0<y2≤1. x is selected, for example, from 0.2, 0.3, 0.4, 0.5 or any two of the aforementioned values; y1 is selected, for example, from 0, 0.2, 0.4, 0.6, 0.8, 0.9, 0.95 or any two of the aforementioned values; and y2 is selected, for example, from 0.05, 0.1, 0.2, 0.4, 0.6, 0.8, 1 or any two of the aforementioned values.

[0059] It should be noted that, in order to improve the stability and solution processing performance of quantum dot 11, in some embodiments of this application, the surface of the quantum dot is connected with ligands. The ligands can be common ligands in the art, including but not limited to C1 to C1. 30 aliphatic carboxylic acid ligands, C6-C 30 Aromatic carboxylic acid ligands, C1-C 30 Aliphatic thiol ligands, C6-C 30 Thiol aromatic ligands, C1-C 30 fatty amine ligands, C6-C 30 Aromatic amine ligands, C1-C 30 Aliphatic phosphine ligands, C6~C 30 Aromatic phosphine ligands and C6-C 30 One or more of aromatic phosphate ligands and halogen ligands.

[0060] Among them, C1~C 30 The aliphatic carboxylic acid ligands include, but are not limited to, one or more of the following: octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, eicosanoic acid, teicosanoic acid, oleic acid, linoleic acid, arachidic acid, arachidonic acid, erucic acid, and docosahexaenoic acid; C6~C 30 Aromatic carboxylic acid ligands include, but are not limited to, one or more of benzoic acid, biphenylic acid, and 1-naphthoic acid. (C1-C2) 30 The aliphatic thiol ligands include, but are not limited to, one or more of hexamethylenetetramine, octanethiol, nonanethiol, decanethiol, undecylthiol, dodecathiol, hexadecylthiol, and octadecylthiol, C6–C6.30 Thiol aromatic ligands include, but are not limited to, one or more of benzenethiol, triphenylmethanethiol, and p-terphenyl-4,4”-dithiol. C1~C 30 The aliphatic amine ligands include, but are not limited to, one or more of hexylamine, octylamine, dioctylamine, trioctylamine, nonylamine, decylamine, dodecylamine, trideamine, tetradeamine, pentadecylamine, hexadecylamine, heptadecanamine, octadecylamine, and oleylamine, C6-C6. 30 The aromatic amine ligands include, but are not limited to, one or more of aniline, indenepropylamine, 4-octylaniline, and benzidine. (C1-C2) 30 The aliphatic phosphine ligands include, but are not limited to, one or more of trimethylphosphine, triethylphosphine, tripropylphosphine, tributylphosphine, trihexylphosphine, trioctylphosphine, tridecylphosphine, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide, and tridecylphosphine oxide, C6–C6. 30 Aromatic phosphine ligands include, but are not limited to, one or more of bis(2-diphenylphosphineethyl)phenylphosphine and triphenylphosphine oxide, C6-C6. 30 The aromatic phosphate ligands include, but are not limited to, one or more of tetraethyl p-xylene diphosphate and ethyl diphenyl phosphate. Halogen ligands include, but are not limited to, -Cl, -F, -I, or -Br.

[0061] To further improve the stability of quantum dots, when the outermost layer of the quantum dot contains sulfur, for example, if the outermost layer of the quantum dot is made of ZnS, a sulfur-containing anion source that is easily decomposed by heat (e.g., at temperatures of 120℃ to 250℃), such as C1 to C2, can be used when preparing the outermost layer of the quantum dot. 30 One or more of the following: aliphatic thiol compounds, diethyl dithiocarbamate, diethyl dithiocarbamate, potassium diethyl xanthate, and hexadecyl xanthate. These sulfur-containing anions are derived from the decomposition of alkane chain anions containing sulfur atoms, which can act as anions to form the outermost layer with cations, and the retained alkane chains (e.g., C1-C30 chain hydrocarbon groups) are tightly connected to the quantum dot surface.

[0062] It is understandable that the aforementioned quantum dots can be synthesized using a conventional hot-injection method. As an example, the synthesis method for quantum dots includes the following steps:

[0063] S1. Preparation of basic solution and anionic precursor, wherein the preparation method of basic solution includes the following steps: providing a container containing a cationic precursor, the cationic precursor being a solution containing a zinc source and a cadmium source, then passing an inert gas through at room temperature, and after the air in the container is completely removed, heating to 125℃~180℃, and maintaining the temperature for 30min~90min in an inert gas atmosphere to remove water and low-boiling-point impurities from the solution to obtain basic solution;

[0064] S2. Heat the base solution to the reaction temperature, inject anionic precursor into it, and ripen it at a constant temperature to obtain the core;

[0065] S3. Multiple layers are sequentially prepared on the surface of the core obtained in step S2 to obtain a reaction solution containing quantum dots.

[0066] Specifically, in step S1, the zinc source includes, but is not limited to, one or more of zinc oleate, zinc stearate, zinc dodecanoate, zinc tetradecanoate, zinc hexadecanoate, zinc palmitate, zinc acetate, zinc acetylacetonate, zinc iodide, zinc bromide, zinc chloride, zinc fluoride, zinc carbonate, zinc cyanide, zinc nitrate, zinc oxide, zinc peroxide, zinc perchlorate, and zinc sulfate. The cadmium source includes, but is not limited to, one or more of cadmium oxide, cadmium acetate, cadmium acetylacetonate, cadmium iodide, cadmium bromide, cadmium chloride, cadmium fluoride, cadmium carbonate, cadmium nitrate, cadmium oxide, cadmium perchlorate, cadmium phosphate, cadmium sulfate, cadmium oleate, cadmium stearate, cadmium dodecanoate, cadmium tetradecanoate, and cadmium hexadecanoate.

[0067] In step S1, the solvent for the cationic precursor includes, but is not limited to, one or more of octadecene, paraffin oil, diphenyl ether, dioctyl ether, oleic acid, stearic acid, palmitic acid, and olive oil. The solvent for the cationic precursor, for example, consists of oleic acid and octadecene. To balance increasing the synthesis yield of quantum dots with improving the mixing efficiency of anion and cation precursors in subsequent processes, in some embodiments of this application, the volume ratio of oleic acid to octadecene is 1:(1-5).

[0068] In order to balance increasing the synthesis yield of quantum dots and improving the solution processing performance of the cationic precursor, in some embodiments of this application, the concentration of zinc in the cationic precursor is 0.05 mol / L to 1 mol / L.

[0069] In the process of purging air from the container, the inert gas includes, but is not limited to, one or more of nitrogen, argon, helium, neon, krypton, and xenon. The flow rate of the inert gas is, for example, 50 mL / min to 300 mL / min, and the purging time is, for example, 10 min to 30 min.

[0070] In step S2, the anion precursor may be a selenium precursor and / or a sulfur precursor, wherein the selenium precursor is selected from at least one of Se-TOP, Se-TBP, Se-TPP, Se-ODE, Se-OA, Se-ODA, Se-TOA, Se-ODPA, Se-OLA, Se-OCA, and Se-DPP; and the sulfur precursor is selected from at least one of S-TOP, S-TBP, S-TPP, S-ODE, S-OA, S-ODA, S-TOA, S-ODPA, S-OLA, S-OCA, S-DPP, mercaptopropylsilane, and alkyl thiols. In step S2, the injection rate of the anion precursor is, for example, 1 mmol / min to 5 mmol / min.

[0071] In step S3, during the formation of multiple layers, in order to improve the layer quality, the injection rate of the anion precursor is, for example, 1 mmol / min to 5 mmol / min.

[0072] To improve the purity of quantum dots, after step S3, conventional methods can be used to separate and purify the reaction products containing quantum dots to obtain purified quantum dots.

[0073] This application also provides an optoelectronic device, which includes, but is not limited to, light-emitting devices, solar cells, or photodetectors, such as... Figure 3 As shown, the optoelectronic device 10 includes multiple functional layers, and at least one of the functional layers is made of a quantum dot as described above, in order to improve the device efficiency and device lifetime of the optoelectronic device 10.

[0074] In some embodiments of this application, see further reference. Figure 3 The multiple functional layers include a light-emitting layer 103, the material of which includes quantum dots as described above. As an example, the quantum dots emit light in blue.

[0075] In some embodiments of this application, the materials of the anode 101 and the cathode 102 are independently selected from one or more of metals, carbon materials, and first metal oxides. The metals include, but are not limited to, one or more of Al, Ag, Cu, Mo, Au, Ba, Pt, Ca, Ir, Ni, and Mg. The carbon materials include, but are not limited to, one or more of graphite, carbon nanotubes, graphene, and carbon fibers. The first metal oxide may be doped or undoped. The doped first metal oxides include, but are not limited to, one or more of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), and magnesium-doped zinc oxide (MZO). The undoped first metal oxides include, but are not limited to, one or more of TiO2, SnO2, ZnO, and In2O3.

[0076] It should be noted that the anode 101 and cathode 102 can also be composite electrodes, which have a sandwich-like structure. The upper and lower layers are made of doped or undoped first metal oxides, respectively, and the middle layer is made of metal, such as one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2. The average thickness of the anode 101 and cathode 102 is, for example, independently selected from 20 nm to 300 nm.

[0077] In some embodiments of this application, see further reference. Figure 3 The plurality of functional layers further includes an electronic functional layer 104, which is disposed between the cathode 102 and the light-emitting layer 103. The electronic functional layer 104 can be a single-layer structure or a multi-layer structure, and the thickness of the electronic functional layer 104 is, for example, 10 nm to 100 nm. When the electronic functional layer 104 is a multi-layer structure, the electronic functional layer 104 includes, for example, one or more of an electron injection layer, an electron transport layer, and a hole blocking layer. For an electronic functional layer 104 including an electron injection layer, an electron transport layer, and a hole blocking layer, the electron transport layer is located between the electron injection layer and the hole blocking layer, and the electron injection layer is closer to the cathode 102 than the hole blocking layer; for an electronic functional layer 104 including an electron transport layer and a hole blocking layer, the electron transport layer is closer to the cathode 102 than the hole blocking layer; for an electronic functional layer 104 including an electron injection layer and an electron transport layer, the electron injection layer is closer to the cathode 102 than the electron transport layer.

[0078] The electronic functional layer 104 includes at least one undoped second metal oxide, at least one IIB-VIA group semiconductor material, at least one IIIA-VA group semiconductor material, at least one IB-IIIA-VIA group semiconductor material, and at least one doped third metal oxide. The undoped second metal oxide is selected from ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, or ZrO2; and / or, the IIB-VIA group semiconductor material is selected from ZnS, ZnSe, or CdS; and / or, the IIIA-VA group semiconductor material is selected from InP or GaP; and / or, the IB-IIIA-VIA group semiconductor material is selected from CuInS or CuGaS; and / or, the host material of the doped third metal oxide is selected from ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, or ZrO2, and the doping element of the doped third metal oxide is, but is not limited to, one or more of Mg, Ca, Zr, W, Ga, Li, Al, Ti, Y, In, and Sn, and the molar percentage of the doping element in the doped third metal oxide is, for example, not higher than 5%, not higher than 10%, not higher than 20%, not higher than 30%, or not higher than 50%. Doped third metal oxides include, but are not limited to, zinc magnesium oxide, zinc calcium oxide, zinc zirconium oxide, zinc gallium oxide, zinc aluminum oxide, zinc lithium oxide, zinc titanium oxide, yttrium zinc oxide, indium tin oxide, or lithium titanium oxide, with Zn as an example. (1-x) Mg x O, Zn (1-x) Ca x O, Zn (1-x) Zr x O, Zn (1-x) Ga x O, Zn (1-x) Al x O, Zn (1-x) Li x O, Al (1-x) Zn x O, Zn (1-x) Ti x O, Zn (1-x) Y x O、In (1-x) Sn x O and Ti (1-x) Li x One or more of O, where 0 < x ≤ 0.5.

[0079] It should be noted that when the electronic functional layer 104 comprises multiple materials and the electronic functional layer 104 has a multi-layer structure, the multiple materials may all be in the same layer, or may be in different layers, or may be partially in the same layer.

[0080] In some embodiments of this application, see further reference. Figure 3 The plurality of functional layers further includes a hole functional layer 105, which is disposed between the light-emitting layer 103 and the anode 101. The hole functional layer 105 can be a single-layer structure or a multi-layer structure, and the thickness of the hole functional layer 105 is, for example, 10 nm to 100 nm. When the hole functional layer 105 is a multi-layer structure, the hole functional layer 105 includes, for example, one or more of a hole injection layer, a hole transport layer, and an electron blocking layer. For a hole functional layer 105 including a hole injection layer, a hole transport layer, and an electron blocking layer, the hole transport layer is located between the hole injection layer and the electron blocking layer, and the hole injection layer is closer to the anode 101 than the electron blocking layer; for a hole functional layer 105 including a hole transport layer and an electron blocking layer, the hole transport layer is closer to the anode 101 than the electron blocking layer; for a hole functional layer 105 including a hole injection layer and a hole transport layer, the hole injection layer is closer to the anode 101 than the hole transport layer.

[0081] The hole functional layer 105 is made of one or more of the following: organic compounds, a first inorganic compound material, and a second inorganic compound material. Among them, the organic compounds include, but are not limited to, poly(3,4-vinyldioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS, CAS No. 155090-83-8), copper phthalocyanine (CAS No. 147-14-8), titanium phthalocyanine (CAS No. 26201-32-1), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (CAS No. 29261-33-4), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (CAS No. 105598-27-4), and polyaniline (CAS No. 25233-30-1). Polypyrrole (CAS No. 30604-81-0), 3-hexyl-substituted polythiophene (CAS No. 104934-50-1), poly(9-vinylcarbazole) (abbreviated as PVK, CAS No. 25067-59-8), 4,4'-bis(9-carbazole)biphenyl (abbreviated as CBP, CAS No. 58328-31-7), poly[bis(4-phenyl)(4-butylphenyl)amine], 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] (abbreviated as TAPC, CAS No. 58473-78-2), poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)di- 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (CAS No. 124729-98-2), 4,4',4'-tris(carbazole-9-yl)triphenylamine (CAS No. 139092-78-7), 4,4',4'-tris(2-naphthylphenylamino)triphenylamine (CAS No. 185) 690-41-9), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (abbreviated as NPB, CAS number 123847-85-8), N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (abbreviated as TPD, CAS number 65181-78-4), N,N'-bis[4-(diphenylamino)phenyl]-N,N'-diphenylbenzidine (CAS number 209980-53-0), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-9,9-spirodifluorene-2,7-diamine (abbreviated as Spiro-TPD),One or more of the following: N2,N7-di-1-naphthyl-N2,N7-diphenyl-9,9'-spirobis[9H-fluorene]-2,7-diamine (CAS No. 932739-76-9), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (abbreviated as PTTA, CAS No. 1333317-99-9), and 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobisfluorene (abbreviated as Spiro-omeTAD, CAS No. 207739-72-8); and / or, the first inorganic compound material includes, but is not limited to, graphene, C60, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, p-type gallium nitride, chromium oxide, and copper oxide. The second inorganic compound material comprises one or more of copper sulfide, molybdenum sulfide, and tungsten sulfide; and / or, the host material of the doped second inorganic compound is selected from graphene, C60, nickel oxide (e.g., NiO), molybdenum oxide (e.g., MoO3), tungsten oxide (e.g., WO3), vanadium oxide (e.g., V2O5), p-type gallium nitride, chromium oxide (e.g., Cr2O3), copper oxide (e.g., CuO or Cu2O), copper sulfide (e.g., CuS), molybdenum sulfide (e.g., MoS2), or tungsten sulfide (e.g., WS2), and the doping element of the doped second inorganic compound is selected from one or more of nickel, molybdenum, tungsten, vanadium, chromium, copper, and platinum group metals, and the molar amount of the doping element accounts for no more than 50% of the total molar amount of the doped second inorganic compound.

[0082] It is understood that when the hole functional layer 105 comprises multiple materials and the hole functional layer 105 has a multi-layer structure, the multiple materials can all be in the same layer, or be in different layers, or partially in the same layer. For example, as Figures 1 to 3 As shown, when the hole functional layer 105 is composed of a hole injection layer 1051 and a hole transport layer 1052 stacked together, the material of the hole functional layer 105 includes PEDOT:PSS and TFB, and PEDOT:PSS and TFB are located in different layers. The material of the hole injection layer 1051 is PEDOT:PSS, and the material of the hole transport layer 1052 is TFB.

[0083] It is understood that the optoelectronic device 10 may also include a substrate disposed on the side of the bottom electrode away from the plurality of functional layers. The substrate may be a rigid substrate or a flexible substrate. The material of the rigid substrate includes, but is not limited to, one or more of glass, ceramic and silicon wafer. The material of the flexible substrate includes, but is not limited to, one or more of polyimide, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate and polyethersulfone.

[0084] It should be noted that the fabrication methods for each functional layer in the optoelectronic device 10 include, but are not limited to, chemical and / or physical methods. Chemical methods include, but are not limited to, one or more of chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, and co-precipitation. Physical methods include, but are not limited to, physical deposition and solution methods. Physical deposition methods include, but are not limited to, one or more of thermal evaporation deposition, electron beam evaporation deposition, magnetron sputtering, multi-arc ion deposition, physical vapor deposition, atomic layer deposition, and pulsed laser deposition. Solution methods include, but are not limited to, one or more of spin coating, printing, inkjet printing, blade coating, dip coating, immersion coating, spray coating, roller coating, casting, slot coating, and strip coating. After fabricating each functional layer of the optoelectronic device, an encapsulation process is required. Encapsulation can be performed using common machine encapsulation or manual encapsulation. In the encapsulation environment, the oxygen and water content are both below 0.1 ppm to ensure the stability of the optoelectronic device. Specifically, the encapsulation material used to form the encapsulation layer is selected from one or more of UV adhesive, metal film and glass adhesive. For example, the encapsulation material is acrylic resin or epoxy resin.

[0085] This application also provides an electronic device, which includes any of the optoelectronic devices described above. The electronic device can be, for example, any electronic product with a display function, including but not limited to smartphones, tablet personal computers, mobile phones, video phones, e-book readers, laptop PCs, netbook computers, workstations, servers, personal digital assistants, portable multimedia players, MP3 players, mobile medical devices, cameras, game consoles, digital cameras, car navigation systems, electronic billboards, ATMs, smart bracelets, smartwatches, virtual reality (VR) devices, or wearable devices.

[0086] The technical solutions and effects of this application will be described in detail below through specific embodiments, comparative examples and experimental examples. The following embodiments are only some embodiments of this application and are not intended to limit this application.

[0087] In the various examples and comparative examples below, the preparation method of Zn(OA)2 solution includes the following steps: 10 mmol of zinc acetate, 10 mL of oleic acid, and 20 mL of octadecene are added sequentially to a 100 mL three-necked flask, argon gas is introduced at room temperature at a flow rate of 100 mL / min, after venting for 15 min, the temperature is raised to 150 °C, and the solution is kept at this temperature for 60 min under an argon atmosphere to obtain Zn(OA)2 solution.

[0088] The preparation method of Cd(OA)2 solution includes the following steps: 5 mmol of cadmium oxide, 5 mL of oleic acid, and 20 mL of octadecene are added sequentially to a 100 mL three-necked flask. Argon gas is introduced at room temperature at a flow rate of 100 mL / min. After venting for 15 min, the temperature is raised to 150 °C and kept at a constant temperature under an argon atmosphere for 60 min. The temperature is then raised to 240 °C and kept at a constant temperature under an argon atmosphere for 30 min to obtain Cd(OA)2 solution.

[0089] The preparation method of S-TOP solution includes the following steps: 5 mmol of sulfur powder and 5 mL of TOP are added sequentially to a 50 mL three-necked flask, argon gas is introduced at room temperature at a flow rate of 50 mL / min, after venting for 15 min, the temperature is raised to 100 °C, and the mixture is stirred at a constant temperature under an argon atmosphere until the sulfur powder is completely dispersed to obtain the S-TOP precursor solution.

[0090] The preparation method of Se-TOP solution includes the following steps: 5 mmol of selenium powder and 5 mL of TOP are added sequentially to a 50 mL three-necked flask, argon gas is introduced at room temperature at a flow rate of 50 mL / min, after venting for 15 min, the temperature is raised to 100 °C, and the mixture is stirred at a constant temperature under an argon atmosphere until the selenium powder is completely dispersed to obtain the Se-TOP precursor solution.

[0091] The preparation method of Zn(DDTC)₂ solution includes the following steps: Under stirring, 20 mmol of sodium diethyldithiocarbamate (NaDDTC) is dissolved in 60 mL of deionized water to obtain a first solution; under stirring, 10 mmol of Zn(Ac)₂·2H₂O is dissolved in 100 mL of deionized water to obtain a second solution; then, the first solution is added dropwise to the second solution, and the mixture is stirred for 2 hours. Solid-liquid separation is then performed, and the white precipitate is collected. Finally, the solution is... The white precipitate was washed several times with deionized water and dried in a vacuum drying oven at room temperature for 24 hours to obtain anhydrous Zn(Ac)2. 10 mL of oleylamine, 20 mL of octadecene, and 15 mmol of anhydrous Zn(Ac)2 were placed in a 100 mL three-necked flask. The flask was heated to 100 °C for 30 min to remove water and oxygen, then cooled to 25 °C, and 5 mmol of Zn(DDTC)2 was added. The flask was heated to 60 °C for 30 min to remove water and oxygen to obtain a Zn(DDTC)2 solution.

[0092] Quantum Dot Example 1

[0093] This embodiment provides a quantum dot and its preparation method. The quantum dot is a blue quantum dot, and its shape is as follows: [Image of a quantum dot with blue quantum dots on the inner-outer radius]. Figure 3 As shown, in the radial direction from the inside out, the quantum dot 11 includes a core 111, a first layer 112, and a second layer 113 arranged sequentially. The first layer 112 covers the core 111, and the second layer 113 covers the first layer 112. The core 111 is made of ZnS with an average particle size of 3 nm; the first layer 112 is made of CdSe with an average thickness of 1 nm; and the second layer 113 is made of Cd... 0.2 Zn 0.8 Se, the average thickness of the second layer 113 is 2 nm. A first interface fusion layer 114 exists between the core 111 and the first layer 112. Along the radial direction from the core 111 to the first layer 112, the molar percentage of ZnS gradually decreases, and the molar percentage of CdSe gradually increases. A second interface fusion layer 115 exists between the first layer 112 and the second layer 113. Along the radial direction from the first layer 112 to the second layer 113, the molar percentage of CdSe gradually decreases, and the molar percentage of CdSe gradually increases. 0.2 Zn 0.8 The molar percentage of Se gradually increases to form an interface with varying energy level gradients.

[0094] Continue reading Figure 3 In the radial direction from the inside out, the quantum dot 11 also includes a third layer 116, a fourth layer 117, and a fifth layer 118 arranged sequentially. The fourth layer 117 covers the third layer 116, and the fifth layer 118 covers the fourth layer 117, that is, the fifth layer 118 is located as the outermost layer. The material of the third layer 116 is ZnSe, and the average thickness of the third layer 116 is 1.5 nm; the material of the fourth layer 117 is CdS, and the average thickness of the fourth layer 117 is 1 nm; the material of the fifth layer 118 is ZnS, and the average thickness of the fifth layer 118 is 0.5 nm.

[0095] In the radial direction from the inside out, taking the core 111 to the second layer 113 as a whole structure (including the core 111, the first interface fusion layer 114, the first layer 112, the second interface fusion layer 115, and the second layer 113), the difference (ΔE) between the valence band top of the third layer 116 and the valence band top of the whole structure is... V,第三层-整体结构 The value is -0.1 eV, and the difference between the conduction band bottom of the overall structure and the conduction band bottom of the third layer 116 (ΔE) is... C,整体结构-第三层 The value is 0.3 eV; the difference between the valence band top of the fourth layer 117 and the valence band top of the overall structure (ΔE) is 0.3 eV. V,第四层-整体结构The difference between the conduction band bottom of the fourth layer 117 and the conduction band bottom of the overall structure (ΔE) is -0.3eV. C,整体结构-第四层 The value is 0.1 eV; the difference between the valence band top of the fifth layer 118 and the valence band top of the overall structure (ΔE) is 0.1 eV. V,第五层-整体结构 The difference between the conduction band bottom of the fifth layer 118 and the conduction band bottom of the overall structure (ΔE) is -0.4 eV. C,整体结构-第五层 The value is 0.35 eV.

[0096] The quantum dot preparation method in this embodiment includes the following steps:

[0097] S10. Take 20 mL of Zn(OA)2 solution and place it in a three-necked flask. Heat the flask to 310 °C and then inject 1 mL of S-TOP solution into it. Let it mature at a constant temperature for 20 min to obtain the first solution containing the core.

[0098] S20. At 310℃, a mixture of 1 mL of Se-TOP solution and 5 mL of Cd(OA)2 solution is injected into the first solution at a rate of 12 mL / h for 30 min. The mixing reaction is carried out for 20 min to obtain a second solution containing the core / first interface fusion layer / first layer.

[0099] S30. At 310℃, a mixture of 1 mL of Se-TOP solution and 1 mL of Cd(OA)2 solution is injected into the second solution at a rate of 6 mL / h for 20 min. The mixture is then reacted for 20 min to obtain a third solution containing a core / first interface fusion layer / first layer / second interface fusion layer / second layer.

[0100] S40. At 300°C, 2 mL of Se-TOP solution is injected into the third solution at a rate of 8 mL / h to obtain the third layer. Subsequently, a mixture of 0.5 mL of S-TOP solution and 2.5 mL of Cd(OA)2 solution is injected at a rate of 10 mL / h to obtain the fourth solution containing the core / first interface fusion layer / first layer / second interface fusion layer / second layer / third layer / fourth layer.

[0101] S50. At 150°C, 0.5 mL of n-dodecyl mercaptan was injected into the fourth solution, and the reaction was carried out for 10 min to obtain a reaction product containing quantum dots.

[0102] S60. Take 40 mL of n-hexane and 40 mL of ethyl acetate into a centrifuge tube, then add the reaction product including quantum dots into the centrifuge tube, then add 60 mL of ethanol, shake well, and centrifuge at 10000 r / min for 5 min. Remove the supernatant and collect the first precipitate. Subsequently, redissolve the first precipitate with 30 mL of n-hexane, add 15 mL of ethanol, shake well, and centrifuge at 10000 r / min for 5 min. Remove the supernatant and collect the second precipitate. The second precipitate is the purified quantum dots.

[0103] Quantum Dot Example 2

[0104] This embodiment provides a quantum dot and its preparation method. Compared with the quantum dot in Quantum Dot Example 1, the difference of the quantum dot in this embodiment is that the material of the second layer is Cd. 0.5 Zn 0.5 Se, correspondingly, will integrate "Cd" in the second interface fusion layer. 0.2 Zn 0.8 Replace "Se" with "Cd" 0.5 Zn 0.5 Se".

[0105] Compared to the quantum dot preparation method in Example 1, the difference in the quantum dot preparation method in this example is that the step S20 "injecting a mixture of 1 mL of Se-TOP solution and 5 mL of Cd(OA)2 solution into the first solution" is replaced with "injecting a mixture of 1 mL of Se-TOP solution and 0.25 mL of Cd(OA)2 solution into the first solution".

[0106] Quantum Dot Example 3

[0107] This embodiment provides a quantum dot and its preparation method. Compared with the quantum dot in Quantum Dot Embodiment 1, the difference of the quantum dot in this embodiment is that the fourth layer is omitted.

[0108] Compared to the quantum dot preparation method in Example 1, the difference in the quantum dot preparation method in this example is that step S40 is replaced by "injecting 2 mL of Se-TOP solution into the third solution at a rate of 8 mL / h at 300 °C to obtain a fourth solution containing a core / first interface fusion layer / first layer / second interface fusion layer / second layer / third layer".

[0109] Quantum Dot Example 4

[0110] This embodiment provides a quantum dot and its preparation method. Compared with the quantum dot in Quantum Dot Embodiment 1, the difference of the quantum dot in this embodiment is that the third layer is omitted.

[0111] Compared to the quantum dot preparation method in Example 1, the difference in the quantum dot preparation method in this example is that step S40 is replaced by "injecting a mixture of 0.5 mL of S-TOP solution and 2.5 mL of Cd(OA)2 solution into the third solution at a rate of 10 mL / h at 300 °C, and reacting to obtain a fourth solution containing a first interface fusion layer / first layer / second interface fusion layer / second layer / fourth layer".

[0112] Quantum Dot Example 5

[0113] This embodiment provides a quantum dot and its preparation method. Compared with the quantum dot in Quantum Dot Example 1, the difference of the quantum dot in this embodiment is that the fifth layer is obtained by S-TOP growth.

[0114] Compared to the quantum dot preparation method in Example 1, the difference in the quantum dot preparation method in this example is that step S50 is replaced with "injecting 0.5 mL of S-TOP solution into the fourth solution at 150 °C, reacting for 10 min, and obtaining a reaction product containing quantum dots".

[0115] Quantum Dot Example 6

[0116] This embodiment provides a quantum dot and its preparation method. The quantum dot is a blue quantum dot, and its shape is as follows: [Image of a quantum dot with blue quantum dots on the inner-outer radius]. Figure 3 As shown, the quantum dot 11 includes a core 111, a first layer 112, and a second layer 113 arranged sequentially. The first layer 112 covers the core 111, and the second layer 113 covers the first layer 112. The core 111 is made of ZnSe with an average particle size of 6 nm; the first layer 112 is made of CdSe with an average thickness of 1 nm; and the second layer 113 is made of CdSe. 0.5 Zn 0.5 S, the average thickness of the second layer 113 is 1 nm. A first interface fusion layer 114 exists between the core 111 and the first layer 112. Along the radial direction from the core 111 to the first layer 112, the molar percentage of ZnSe gradually decreases, and the molar percentage of CdSe gradually increases. A second interface fusion layer 115 exists between the first layer 112 and the second layer 113. Along the radial direction from the first layer 112 to the second layer 113, the molar percentage of CdSe gradually decreases, and the molar percentage of CdSe gradually increases. 0.5 Zn 0.5 The molar percentage of S gradually increases to form an interface with varying energy level gradients.

[0117] Along the radial direction from the inside out, the quantum dot 11 also includes a third layer 116, a fourth layer 117, and a fifth layer 118 arranged sequentially. The fourth layer 117 covers the third layer 116, and the fifth layer 118 covers the fourth layer 117, meaning the fifth layer 118 is the outermost layer. The material of the third layer 116 is CdZnSe, and the average thickness of the third layer 116 is 1 nm; the material of the fourth layer 117 is CdZnS, and the average thickness of the fourth layer 117 is 0.5 nm; the material of the fifth layer 118 is ZnS, and the average thickness of the fifth layer 118 is 0.25 nm.

[0118] The quantum dot preparation method in this embodiment includes the following steps:

[0119] S100. Take 15 mL of Zn(OA)2 solution and place it in a three-necked flask. Heat the flask to 310℃ and then inject 1 mL of Se-TOP solution into it. Let it mature at a constant temperature for 20 min to obtain the first solution containing the core.

[0120] S200. At 310℃, a mixture of 1 mL of Se-TOP solution and 5 mL of Cd(OA)2 solution is injected into the first solution at a rate of 12 mL / h for 30 min. The mixing reaction is carried out for 20 min to obtain a second solution containing the core / first layer.

[0121] S300, at 310℃, a mixture of 1 mL of S-TOP solution and 2.5 mL of Cd(OA)2 solution was injected into the second solution at a rate of 12 mL / h for 20 min. The mixing reaction was carried out for 20 min to obtain a third solution containing a quantum dot core.

[0122] S400, at 290°C, a mixture of 1 mL of Se-TOP solution and 2.5 mL of Cd(OA)2 solution is injected into the third solution at a rate of 8 mL / h to obtain the third layer; subsequently, a mixture of 1 mL of S-TOP solution and 2.5 mL of Cd(OA)2 solution is injected at a rate of 10 mL / h to obtain the fourth solution containing the core / third layer / fourth layer;

[0123] S500, at 150℃, 2 mL of Zn(DDTC)2 solution was injected into the fourth solution and reacted for 10 min to obtain the reaction product containing quantum dots;

[0124] S60. Take 40 mL of n-hexane and 40 mL of ethyl acetate into a centrifuge tube, then add the reaction product including quantum dots into the centrifuge tube, then add 60 mL of ethanol, shake well, and centrifuge at 10000 r / min for 5 min. Remove the supernatant and collect the first precipitate. Subsequently, redissolve the first precipitate with 30 mL of n-hexane, add 15 mL of ethanol, shake well, and centrifuge at 10000 r / min for 5 min. Remove the supernatant and collect the second precipitate. The second precipitate is the purified quantum dots.

[0125] Quantum Dot Comparison Example 1

[0126] This comparative example provides a quantum dot and its preparation method. Compared with the quantum dot in Example 1, the difference of the quantum dot in this example is that the core material of the quantum dot is Cd. 0.2 Zn 0.8 Se, the average particle size of the quantum dot core is 6nm, and the first interface fusion layer, the first layer, the second interface fusion layer and the second layer are omitted.

[0127] Compared to the quantum dot preparation method in Example 1, the difference in the quantum dot preparation method in this comparative example is that steps S20 and S30 are omitted, and step S10 is replaced by "taking 10 mL of Zn(OA)2 solution and placing it in a three-necked flask, heating it to 310°C, and injecting a mixture of 0.5 mL of Se-TOP solution and 1 mL of Cd(OA)2 solution into the first solution at a rate of 12 mL / h, mixing and reacting for 20 min to obtain a third solution containing the core of quantum dots".

[0128] Quantum Dot Comparison Example 2

[0129] This comparative example provides a quantum dot and its preparation method. The quantum dot in this comparative example is Cd. 0.1 Zn 0.9 Se(core) / Cd 0.3 Zn 0.7 S (intermediate shell) / ZnS (outer shell), wherein the average particle size of the quantum dot nucleus is 4nm, the average thickness of the intermediate shell is 2nm, and the average thickness of the outer shell is 1nm.

[0130] Experimental Example 1

[0131] The energy levels of the quantum dots in Quantum Dot Examples 1 to 6, Comparative Examples 1 and 2 were detected using ultraviolet electron spectroscopy. The energy levels of the overall structure of the quantum dots in Quantum Dot Examples 1, 2 and 6 are shown in Table 1 below:

[0132] Table 1

[0133]

[0134] Note: ΔE V,整体结构-第一层 This represents the difference between the valence band top of the overall structure and the valence band top of the first layer (i.e., E). V整体结构 Subtract E V第一层 (value);

[0135] ΔE C,整体结构-第一层 ΔE represents the difference between the bottom of the conduction band of the overall structure and the bottom of the conduction band of the first layer. V,第一层-第二层 ΔE represents the difference between the peak of the first price band and the peak of the second price band. C,第一层-第二层 This represents the difference between the bottom of the first layer and the bottom of the second layer.

[0136] Furthermore, testing revealed that for the quantum dot in Example 1, the overall band gap was 3.6 eV, the band gap of the first layer was 1.9 eV, and the band gap of the second layer was 2.4 eV. For the quantum dot in Example 6, the overall band gap was 2.7 eV, the band gap of the first layer was 2.4 eV, and the band gap of the second layer was 2.6 eV.

[0137] The energy levels of partial layers of quantum dots in Quantum Dot Examples 1 to 6, as well as Quantum Dot Comparative Examples 1 and 2, are shown in Table 2 below:

[0138] Table 2

[0139]

[0140]

[0141] Note: ΔE V,第三层-整体结构 ΔE represents the difference between the valence band peak of the third layer and the valence band peak of the overall structure. C,整体结构-第三层 ΔE represents the difference between the bottom of the conduction band of the overall structure and the bottom of the conduction band of the third layer. V,第四层-整体结构 ΔE represents the difference between the valence band peak of the fourth layer and the valence band peak of the overall structure. C,整体结构-第四层 ΔE represents the difference between the bottom of the conduction band of the overall structure and the bottom of the conduction band of the fourth layer. V,第五层-整体结构 ΔE represents the difference between the valence band peak of the fifth layer and the valence band peak of the overall structure. C,整体结构-第五层 This represents the difference between the bottom of the overall structure's conductor strip and the bottom of the fifth layer's conductor strip.

[0142] The photoluminescence wavelength, full width at half maximum (FWHM), and photoluminescence efficiency of the quantum dots in Quantum Dot Examples 1 to 6, as well as Quantum Dot Comparative Examples 1 and 2, are shown in Table 3 below:

[0143] Table 3

[0144]

[0145] Device Example 1

[0146] This embodiment provides an optoelectronic device and its fabrication method. The optoelectronic device is a quantum dot light-emitting diode with a positive-position structure, such as... Figure 4 As shown, from bottom to top, the optoelectronic device 10 includes an anode 101, a hole functional layer 105, a light-emitting layer 103, an electron functional layer 104, and a cathode 102, which are stacked sequentially. The hole functional layer 105 consists of a hole injection layer 1051 and a hole transport layer 1052 stacked together, with the hole injection layer 1051 closer to the anode 101 than the hole transport layer 1052. The electron functional layer 104 is a single-layer structure and serves as an electron transport layer. The light-emitting area of ​​the optoelectronic device 10 is 0.04 cm². 2 .

[0147] The structural composition of each layer in optoelectronic device 10 is as follows:

[0148] The anode 101 is made of ITO and has an average thickness of 80 nm.

[0149] The cathode 102 is made of Ag and has an average thickness of 100 nm.

[0150] The hole injection layer 1051 is made of PEDOT:PSS, and the average thickness of the hole injection layer 1051 is 40nm.

[0151] The hole transport layer 1052 is made of TFB material and has an average thickness of 30 nm.

[0152] The material of the light-emitting layer 103 is the quantum dot in Quantum Dot Example 1, and the average thickness of the light-emitting layer 103 is 40 nm;

[0153] The material of electronic functional layer 104 is Zn 0.85 Mg 0.15 O nanoparticles (average particle size of 5 nm) and electronic functional layer 104 with an average thickness of 40 nm.

[0154] The method for fabricating the optoelectronic device in this embodiment includes the following steps:

[0155] S10.1 Provide a glass substrate, sputter ITO on one side of the substrate to obtain an ITO layer, wipe the surface of the ITO layer with a small amount of soapy water using a cotton swab to remove visible impurities, and then sequentially ultrasonically clean the substrate including ITO with deionized water for 15 min, acetone for 15 min, ethanol for 15 min, and isopropanol for 15 min, and after drying, perform ultraviolet-ozone surface treatment for 20 min to obtain a substrate including an anode.

[0156] S10.2 Under normal temperature and pressure air environment, spin-coat PEDOT:PSS aqueous solution on the side of the anode away from the substrate, and then place it under nitrogen atmosphere at 150℃ for constant temperature heat treatment to solidify into a film to obtain hole injection layer.

[0157] S10.3 Under normal temperature and pressure nitrogen atmosphere, spin-coat a TFB-chlorobenzene solution with a concentration of 8 mg / mL on the side of the hole injection layer away from the anode, and then place it under constant temperature heat treatment at 150℃ nitrogen atmosphere to solidify into a film to obtain the hole transport layer.

[0158] S10.4 Under normal temperature and pressure nitrogen atmosphere, spin-coat a quantum dot-n-hexane solution with a concentration of 25 mg / mL on the side of the hole transport layer away from the hole injection layer, and then place it under a nitrogen atmosphere at 80℃ for constant temperature heat treatment to solidify into a film to obtain the light-emitting layer.

[0159] S10.5 Under a nitrogen atmosphere at normal temperature and pressure, spin-coat a Zn solution with a concentration of 30 mg / mL onto the side of the luminescent layer away from the hole transport layer. 0.85 Mg 0.15 The O-ethanol solution was then subjected to constant temperature heat treatment at 100°C under a nitrogen atmosphere to solidify it into a film, thereby obtaining an electronic functional layer.

[0160] S10.6. Place the laminated structure obtained after step S10.5 into a vacuum coating machine and evacuate it to a vacuum level of 4×10⁻⁶. -6 mbar is used to deposit Ag on the side of the electronic functional layer away from the light-emitting layer through a mask to obtain the cathode. Finally, it is encapsulated with UV-curable adhesive to obtain the optoelectronic device.

[0161] Device Example 2

[0162] This embodiment provides an optoelectronic device and its fabrication method. Compared with the optoelectronic device in Device Embodiment 1, the difference of the optoelectronic device in this embodiment is that the material of the light-emitting layer is replaced with quantum dots as in Quantum Dot Embodiment 2.

[0163] The fabrication method of the optoelectronic device in this embodiment is the same as that in Device Example 1.

[0164] Device Example 3

[0165] This embodiment provides an optoelectronic device and its fabrication method. Compared with the optoelectronic device in Device Embodiment 1, the difference of the optoelectronic device in this embodiment is that the material of the light-emitting layer is replaced with the quantum dots in Quantum Dot Embodiment 3.

[0166] The fabrication method of the optoelectronic device in this embodiment is the same as that in Device Example 1.

[0167] Device Example 4

[0168] This embodiment provides an optoelectronic device and its fabrication method. Compared with the optoelectronic device in Device Embodiment 1, the difference of the optoelectronic device in this embodiment is that the material of the light-emitting layer is replaced with the quantum dots in Quantum Dot Embodiment 4.

[0169] The fabrication method of the optoelectronic device in this embodiment is the same as that in Device Example 1.

[0170] Device Example 5

[0171] This embodiment provides an optoelectronic device and its fabrication method. Compared with the optoelectronic device in Device Embodiment 1, the difference of the optoelectronic device in this embodiment is that the material of the light-emitting layer is replaced with the quantum dots in Quantum Dot Embodiment 5.

[0172] The fabrication method of the optoelectronic device in this embodiment is the same as that in Device Example 1.

[0173] Device Example 6

[0174] This embodiment provides an optoelectronic device and its fabrication method. Compared with the optoelectronic device in Device Embodiment 1, the difference of the optoelectronic device in this embodiment is that the material of the light-emitting layer is replaced with the quantum dots in Quantum Dot Embodiment 6.

[0175] The fabrication method of the optoelectronic device in this embodiment is the same as that in Device Example 1.

[0176] Device Comparison Example 1

[0177] This comparative example provides an optoelectronic device and its fabrication method. Compared with the optoelectronic device in Device Example 1, the difference in this comparative example is that the material of the light-emitting layer is replaced with quantum dots as in Comparative Example 1.

[0178] The fabrication method of the optoelectronic device in this comparative example is the same as that in Device Example 1.

[0179] Device Comparison Example 2

[0180] This comparative example provides an optoelectronic device and its fabrication method. Compared with the optoelectronic device in Device Example 1, the difference in this comparative example is that the material of the light-emitting layer is replaced with quantum dots as in Comparative Example 2.

[0181] The fabrication method of the optoelectronic device in this comparative example is the same as that in Device Example 1.

[0182] Experimental Example

[0183] The performance of the optoelectronic devices in Device Examples 1 to 6, Device Comparative Examples 1 and 2 after 1 hour of packaging was tested. The performance tests were conducted in an environment with a temperature of 25°C and a relative humidity of 40%.

[0184] The photoelectric performance was tested using a Fostar FPD optical property measurement system (comprising a Marine Optics USB2000, a LabVIEW-controlled QE-PRO spectrometer, a Keithley 2400, a high-precision digital source meter Keithley 6485, a 50μm inner diameter optical fiber, device test probes and fixtures, various connecting cables and data cards, an efficiency test cassette, and a data acquisition system). The system acquired parameters such as the turn-on voltage, current, brightness, and emission spectrum of each photoelectric device, and then calculated the maximum external quantum efficiency (EQE). max Key parameters include (%), power efficiency, etc.

[0185] The device lifetime testing method includes the following steps: under constant current (2mA) driving, electroluminescence lifetime analysis is performed on each optoelectronic device using lifetime testing equipment, the time required for each optoelectronic device to decay from maximum brightness to 95% (T95,h) is recorded, and the time required for each optoelectronic device to decay from 100% brightness to 95% brightness at 1000nit brightness (T95@1000nit,h) is calculated by using the decay fitting formula.

[0186] The performance test data for each optoelectronic device are detailed in Table 4 below:

[0187] Table 4

[0188]

[0189] As shown in Table 1, compared with the optoelectronic devices in Device Comparative Example 1 and Device Comparative Example 2, the optoelectronic devices in Device Examples 1 to 6 have superior optoelectronic performance and device lifetime. Taking the optoelectronic devices in Device Example 1 and Device Comparative Example 2 as examples, the EQE of the optoelectronic device in Device Example 1 is significantly higher. max The EQE of the optoelectronic device in Comparative Example 2 max The T95 of the optoelectronic device in Device Example 1 is 2.2 times that of the optoelectronic device in Device Comparative Example 2, and the T95 of the optoelectronic device in Device Example 1 is 3.6 times that of the optoelectronic device in Device Comparative Example 2.

[0190] This demonstrates that using quantum dots as the luminescent material for optoelectronic devices according to the embodiments of this application can improve the device efficiency and lifetime of optoelectronic devices, and is also beneficial to improving the performance stability of optoelectronic devices. The reasons are as follows: First, the overall structure of the quantum dots is a large-size trap structure, which is beneficial to increase the exciton confinement effect, confine excitons away from the surface, avoid excitons being captured by surface defects, and improve the fluorescence quantum efficiency of quantum dots; Second, by designing a layered structure to obtain a long exciton lifetime, the probability of generating nonradiative Auger recombination is reduced.

[0191] The foregoing has provided a detailed description of a quantum dot and an optoelectronic device comprising a quantum dot, as provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A quantum dot, characterized in that, In the radial direction from the inside out, the quantum dot includes a core, a first layer and a second layer arranged sequentially, the first layer covering the core and the second layer covering the first layer; the band gap of the first layer is smaller than the band gap of the core, and the band gap of the first layer is smaller than the band gap of the second layer.

2. The quantum dot according to claim 1, characterized in that, The band gap of the second layer is no larger than the band gap of the core; And / or, the quantum dots are blue quantum dots; And / or, the difference between the valence band top of the core and the valence band top of the first layer is not greater than -0.2 eV, and the difference between the conduction band bottom of the core and the conduction band bottom of the first layer is not less than 0.2 eV; the difference between the valence band top of the first layer and the valence band top of the second layer is not less than 0.2 eV, and the difference between the conduction band bottom of the first layer and the conduction band bottom of the second layer is not greater than -0.2 eV; And / or, the average particle size of the nucleus is 2 nm to 8 nm; And / or, the average thickness of the first layer is 1 nm to 3 nm; And / or, the average thickness of the second layer is 1 nm to 4 nm; And / or, the average particle size of the quantum dot nucleus is 4 nm to 15 nm.

3. The quantum dot according to claim 1 or 2, characterized in that, The core is made of a first compound, the first layer is made of a second compound, and the second layer is made of a third compound. The quantum dot further includes a first interface fusion layer located between the core and the first layer. The material of the first interface fusion layer includes the first compound and the second compound. Along the radial direction from the core to the first layer, the molar percentage of the first compound gradually decreases and the molar percentage of the second compound gradually increases. And / or, the quantum dot further includes a second interface fusion layer located between the first layer and the second layer, the material of the second interface fusion layer comprising the second compound and the third compound, wherein the molar percentage of the second compound gradually decreases and the molar percentage of the third compound gradually increases along the radial direction from the first layer to the second layer; optionally, the thickness of the second interface fusion layer is 0.2 nm to 2 nm.

4. The quantum dot according to claim 1, characterized in that, The material of the core, the material of the first layer, and the material of the second layer are each independently selected from one or more of group II-VI compounds, group III-V compounds, group III-VI compounds, group IV-VI compounds, and group I-III-VI compounds; Wherein, the II-VI compound is selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe , HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, CdZnSeS, CdZnSeT e, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; and / or, the III-V compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, In One or more of PAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; and / or, the III-VI compounds are selected from one or more of In2S3, In2Se3, InGaS3, and InGaSe3; and / or, the IV-VI compounds are selected from SnS, SnSe, and S One or more of nTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; and / or, the group I-III-VI compounds are selected from one or more of AgInS, AgInS2, CuInS, CuInS2, AgGaS2, CuGaS2, CuGaO2, AgGaO2, AgAlO2, AgInGaS2, and CuInGaS2.

5. The quantum dot according to claim 4, characterized in that, The core material is ZnA, the first layer material is CdM, and the second layer material is Cd. x Zn (1-x) N; Wherein, Zn is zinc, Cd is cadmium, A, M and N are independently selected from Se or S, and 0.2≤x≤0.

5.

6. The quantum dot according to any one of claims 1 to 5, characterized in that, The quantum dot further includes a layer for coating the second layer, the first layer, and the core, wherein the layer for coating the second layer, the first layer, and the core is selected from one or more of a third layer having a hole confinement structure, a fourth layer having an electron confinement structure, and a fifth layer having a Type I confinement structure; In the radial direction from the inside to the outside, taking the core to the second layer as a whole structure, the absolute value of the difference between the valence band top of the third layer and the valence band top of the whole structure is greater than 0 eV and not less than 0.2 eV, and the absolute value of the difference between the conduction band bottom of the whole structure and the conduction band bottom of the third layer is not less than 0.2 eV and not greater than 0.8 eV; The absolute value of the difference between the valence band top of the fourth layer and the valence band top of the overall structure is not less than 0.2 eV and not greater than 0.8 eV, and the absolute value of the difference between the conduction band bottom of the overall structure and the conduction band bottom of the fourth layer is greater than 0 eV and not greater than 0.2 eV; The absolute value of the difference between the valence band top of the fifth layer and the valence band top of the overall structure is not less than 0.2 eV and not greater than 0.8 eV, and the absolute value of the difference between the conduction band bottom of the overall structure and the conduction band bottom of the fifth layer is not less than 0.2 eV and not greater than 0.8 eV.

7. The quantum dot according to claim 6, characterized in that, The quantum dot includes the third layer and the fifth layer, with the fifth layer located on the outermost layer; Alternatively, the quantum dot may include the fourth layer and the fifth layer, with the fifth layer being the outermost layer; Alternatively, the quantum dot may include the third layer, the fourth layer, and the fifth layer, with the fifth layer being the outermost layer and the fourth layer being located between the third layer and the fifth layer, or the third layer being located between the fourth layer and the fifth layer.

8. The quantum dot according to claim 7, characterized in that, The material of the third layer is Cd. y1 Zn (1-y1) Se, where 0 ≤ y1 < 1, and / or the average thickness of the third layer is 1 nm to 3 nm; And / or, the material of the fourth layer is Cd. y2 Zn (1-y2) S, where 0 < y2 ≤ 1, and / or the average thickness of the fourth layer is 1 nm to 3 nm; And / or, the material of the fifth layer is ZnS, and / or the average thickness of the fifth layer is 0.5nm to 2nm; And / or, the average thickness of the shell of the quantum dot is 2.5 nm to 8 nm.

9. The quantum dot according to any one of claims 1 to 5, 7 and 8, characterized in that, The general structural formula of the quantum dot is any of the following: (A1)ZnA / CdM / Cd x Zn (1-x) N / C y1 Zn (1-y1) Se / Cd y2 Zn (1-y2) S / ZnS; (A2)ZnA / CdM / Cd x Zn (1-x) N / Cd y1 Zn (1-y1) Se / ZnS; (A3)ZnA / CdM / Cd x Zn (1-x) N / C y2 Zn (1-y2) S / ZnS; Where A, M and N are independently selected from Se or S elements, 0.2≤x≤0.5, 0≤y1<1, 0<y2≤1.

10. An optoelectronic device, characterized in that, include: Anode and cathode arranged opposite each other; as well as Multiple functional layers are disposed between the anode and the cathode; Wherein, at least one of the plurality of functional layers is made of a quantum dot as described in any one of claims 1 to 9; Preferably, the plurality of functional layers include a light-emitting layer, the material of which includes quantum dots as described in any one of claims 1 to 9.

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