Light-emitting device, preparation method of light-emitting device and electronic equipment

Abstract

The invention discloses a light-emitting device, a preparation method of the light-emitting device and electronic equipment, in the light-emitting device, a material of a light-emitting layer comprises a quantum dot with a core-shell structure, and the matching degree between a hole injection level and an electron injection level can be improved by regulating and controlling the average particle size of a core body in the quantum dot and the thickness of a shell layer; the carrier transport balance is promoted, so that the photoelectric property and the service life of the light-emitting device are improved; the light-emitting device is applied to the electronic equipment, so that the display effect and the service life of the electronic equipment are improved.

Description

Technical Field

[0001] The present application relates to the field of optoelectronic technologies, and particularly relates to a light-emitting device, a method for manufacturing a light-emitting device, and an electronic device. Background Art

[0002] A light-emitting device refers to a device that emits light through the injection and recombination of carriers, including but not limited to an Organic Light-Emitting Diode (OLED) and a Quantum Dot Light Emitting Diode (QLED). The light-emitting device has a "sandwich" structure, that is, it includes an anode, a cathode, and a light-emitting layer. Among them, the anode and the cathode are disposed opposite to each other, and the light-emitting layer is disposed between the anode and the cathode. The light-emitting principle of the light-emitting device is as follows: electrons are injected from the cathode of the device into the light-emitting region, holes are injected from the anode of the device into the light-emitting region, electrons and holes recombine in the light-emitting region to form excitons, and the recombined excitons release photons in the form of radiative transition, thereby emitting light.

[0003] After years of development, the light-emitting device has made great progress in performance indicators and also shown great potential for application and development. However, there are still deficiencies at present. For example, the device lifetime of QLED needs to be further improved, especially for blue QLED. Therefore, how to improve the device lifetime of QLED is of great significance to the application and development of QLED. Summary of the Invention

[0004] The present application provides a light-emitting device, a method for manufacturing a light-emitting device, and an electronic device to improve the device lifetime of QLED.

[0005] In a first aspect, the present application provides a light-emitting device, which includes:

[0006] An anode and a cathode disposed opposite to each other; and

[0007] A light-emitting layer disposed between the anode and the cathode;

[0008] Wherein, the material of the light-emitting layer includes quantum dots having a core-shell structure, the average particle size of the core of the quantum dots is less than 5 nm, and the thickness of the shell of the quantum dots is less than 2.5 nm.

[0009] Optionally, the average particle size of the core of the quantum dots is 1 nm to 4 nm, and / or the thickness of the shell of the quantum dots is 1 nm to 2.5 nm; and / or

[0010] The difference between the conduction band energy level of the shell of the quantum dots and the conduction band energy level of the core of the quantum dots is not greater than 0.2 eV; and / or

[0011] The energy level difference between the valence band of the shell of the quantum dots and the valence band of the core of the quantum dots is not less than 0.8 eV.

[0012] Optionally, the average particle size of the quantum dots is 2 nm to 25 nm; and / or

[0013] The energy level difference between the valence band of the shell of the quantum dots and the valence band of the core of the quantum dots is 0.8 eV to 1.0 eV; and / or

[0014] The quantum dots are blue quantum dots; and / or

[0015] The material of the core of the quantum dots and the material of the shell of the quantum dots are independently selected from one or more of II-VI group compounds, III-VI group compounds, III-V group compounds, IV-VI group compounds, and I-III-VI group compounds; optionally, the II-VI group compounds are selected from one or more of 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, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the III-VI group compounds are selected from one or more of In2S3, In2Se3, InGaS3, and InGaSe3; the III-V group compounds are selected from one or more of 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, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the IV-VI group compounds are selected from one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; the I-III-VI group compounds are selected from one or more of AgInS, AgInS2, CuInS, CuInS2, AgGaS2, CuGaS2, CuGaO2, AgGaO2, AgAlO2, AgInGaS2, and CuInGaS2; and / or

[0016] The quantum dots are selected from any one of the following:

[0017] (1) Zn x1 Cd (1-x1) Se / ZnSe / Cd x2 Zn (1-x2) S / ZnS, 0.85 ≤ x1 ≤ 0.95, 0.1 ≤ x2 ≤ 0.5;

[0018] (2) Zn y1 Cd (1-y1) Se / ZnSe / ZnS / Cd y2 Zn (1-y2) S / ZnS, 0.85 ≤ y1 ≤ 0.95, 0.1 ≤ y2 ≤ 0.5;

[0019] (3) Zn z1 Cd (1-z1) Se / Cd z2 Zn (1-z2) S / ZnS, 0.85 ≤ z1 ≤ 0.95, 0.1 ≤ z2 ≤ 0.5;

[0020] (4) Cd t1 Zn (1 - t1) Se / ZnSe t2 S (1-t2) / Cd t3 Zn (1-t3) S / ZnS, 0.85 ≤ t1 ≤ 0.95, 0.4 ≤ t2 ≤ 1, 0.1 ≤ t3 ≤ 0.5;

[0021] (5) Cd r1 Zn (1-r1) Se / ZnSe / Cd r2 Zn (1-r2) S, 0.85 ≤ r1 ≤ 0.95, 0.1 ≤ r1 ≤ 0.3.

[0022] Optionally, the light-emitting layer includes N quantum dot layers, the materials of each quantum dot layer are independently selected from the quantum dots, and the quantum dots in each quantum dot layer are arranged in a single layer, where N is a positive integer greater than or equal to 1.

[0023] Optionally, the thickness of the light-emitting layer is 2 nm to 60 nm; and / or

[0024] N is 2, and the light-emitting layer is composed of a first quantum dot layer and a second quantum dot layer arranged in a stack.

[0025] Optionally, the light-emitting device further includes an electron functional layer disposed between the cathode and the light-emitting layer, and the material of the electron functional layer includes one or more of an undoped first inorganic compound and a doped second inorganic compound;

[0026] Among them, the undoped first inorganic compound includes one or more of an undoped first metal oxide, a IIB-VIA group semiconductor material, a IIIA-VA group semiconductor material, and a IB-IIIA-VIA group semiconductor material. The undoped first metal oxide includes one or more of ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, and ZrO2, and / or the IIB-VIA group semiconductor material includes one or more of ZnS, ZnSe, and CdS, and / or the IIIA-VA group semiconductor material includes one or more of InP and GaP, and / or the IB-IIIA-VIA group semiconductor material includes one or more of CuInS and CuGaS;

[0027] And / or, the doped second inorganic compound includes a second metal oxide doped with a first doping element. The second metal oxide is selected from ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, or ZrO2, and the first doping element is selected from one or more of Mg, Ca, Zr, W, Ga, Li, Al, Ti, Y, In, and Sn;

[0028] And / or, the light-emitting device further includes a hole functional layer disposed between the anode and the light-emitting layer, and the material of the hole functional layer includes one or more of an organic compound, an undoped third inorganic compound, and a doped fourth inorganic compound; wherein, the organic compound is selected from one or more of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid), copper phthalocyanine, titanium oxyphthalocyanine, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, polypyrrole, polyaniline, 3-hexyl-substituted polythiophene, poly(9-vinylcarbazole), 4,4'-bis(9-carbazolyl)biphenyl, poly[bis(4-phenyl)(4-butylphenyl)amine], 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline], poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine)], poly[(N,N'-(4-n-butylphenyl)-N,N'-diphenyl-1,4-phenylenediamine)-ALT-(9,9-din-octylfluorene-2,7-diyl)], 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, 4,4',4''-tris(carbazol-9-yl)triphenylamine, 4,4',4'-tris(2-naphthylphenylamino)triphenylamine, N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine, N,N'-bis[4-(diphenylamino)phenyl]-N,N'-diphenylbenzidine, N,N'-bis(3-methylphenyl)-N,N'-diphenyl-9,9-spirobifluorene-2,7-diamine, N2,N7-di-1-naphthyl-N2,N7-diphenyl-9,9'-spirobi[9H-fluorene]-2,7-diamine, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], and 2,2',7,7'-tetra[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, and / or the undoped third inorganic compound is selected from one or more of graphene, C60, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, p-type gallium nitride, chromium oxide, copper oxide, copper sulfide, molybdenum sulfide, and tungsten sulfide, and / or the doped fourth inorganic compound is a host inorganic compound doped with a second doping element, and the host inorganic compound is selected from one or more of graphene, C60, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, p-type gallium nitride, chromium oxide, copper oxide, copper sulfide, molybdenum sulfide, and tungsten sulfide, and / or the second doping element is selected from one or more of nickel, molybdenum, tungsten, vanadium, chromium, copper, and platinum group metal elements;

[0029] And / or, the materials of the anode and the cathode are independently selected from one or more of metals, carbon materials, and third metal oxides, wherein the metal is selected from one or more of Al, Ag, Cu, Mo, Au, Ba, Pt, Ca, Ir, Ni, and Mg, and / or the carbon material is selected from one or more of graphite, carbon nanotubes, graphene, and carbon fibers, and / or the third metal oxide is selected from one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, aluminum-doped magnesium oxide, SnO2, ZnO, and In2O3.

[0030] In a second aspect, the present application provides a method for preparing a light-emitting device, including the following steps:

[0031] Providing a bottom electrode and forming a light-emitting layer on one side of the bottom electrode; and

[0032] Forming a top electrode on the side of the light-emitting layer away from the bottom electrode;

[0033] Wherein, one of the bottom electrode and the top electrode is an anode, and the other is a cathode; the material of the light-emitting layer includes quantum dots with a core-shell structure, the average particle size of the core of the quantum dots is less than 5 nm, and the thickness of the shell of the quantum dots is less than 2.5 nm.

[0034] Optionally, the difference between the conduction band energy level of the shell of the quantum dots and the conduction band energy level of the core of the quantum dots is not greater than 0.2 eV; and / or

[0035] The difference between the valence band energy level of the shell of the quantum dots and the valence band energy level of the core of the quantum dots is not less than 0.8 eV; and / or

[0036] The method for forming the light-emitting layer includes the steps of:

[0037] Depositing a dispersion liquid containing the quantum dots to obtain a first film layer; and

[0038] Performing a drying treatment on the first film layer to obtain the light-emitting layer;

[0039] Wherein, the first film layer includes N quantum dot layers, the material of each quantum dot layer is the quantum dots, and the quantum dots in each quantum dot layer are arranged in a single layer, N is a positive integer greater than or equal to 1; the number of formed quantum dot layers is controlled by adjusting the concentration of the quantum dots in the dispersion liquid.

[0040] Optionally, the relationship between the number of formed quantum dot layers and the concentration of the quantum dots in the dispersion liquid is as follows:

[0041] (B1) When N is 1, the concentration of the quantum dots in the dispersion liquid is 5 mg / mL to 7 mg / mL;

[0042] (B2) When N is 2, the concentration of the quantum dots in the dispersion liquid is 21 mg / mL to 24 mg / mL;

[0043] (B3) When N is 3, the concentration of the quantum dots in the dispersion liquid is 28 mg / mL to 32 mg / mL.

[0044] Optionally, the method for preparing the light-emitting device further includes the step of forming a hole functional layer between the anode and the light-emitting layer; the material of the hole functional layer includes one or more of an organic compound, an undoped third inorganic compound, and a doped fourth inorganic compound; wherein, the organic compound is selected from one or more of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid), copper phthalocyanine, titanium oxyphthalocyanine, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, polypyrrole, polyaniline, 3-hexyl-substituted polythiophene, poly(9-vinylcarbazole), 4,4'-bis(9-carbazolyl)biphenyl, poly[bis(4-phenyl)(4-butylphenyl)amine], 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline], poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine)], poly[(N,N'-(4-n-butylphenyl)-N,N'-diphenyl-1,4-phenylenediamine)-ALT-(9,9-din-octylfluorene-2,7-diyl)], 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, 4,4',4''-tris(carbazol-9-yl)triphenylamine, 4,4',4'-tris(2-naphthylphenylamino)triphenylamine, N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine, N,N'-bis[4-(diphenylamino)phenyl]-N,N'-diphenylbenzidine, N,N'-bis(3-methylphenyl)-N,N'-diphenyl-9,9-spirobifluorene-2,7-diamine, N2,N7-di-1-naphthyl-N2,N7-diphenyl-9,9'-spirobi[9H-fluorene]-2,7-diamine, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], and 2,2',7,7'-tetra[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, and / or the undoped third inorganic compound is selected from one or more of graphene, C60, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, p-type gallium nitride, chromium oxide, copper oxide, copper sulfide, molybdenum sulfide, and tungsten sulfide, and / or the doped fourth inorganic compound is a host inorganic compound doped with a second doping element, the host inorganic compound is selected from one or more of graphene, C60, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, p-type gallium nitride, chromium oxide, copper oxide, copper sulfide, molybdenum sulfide, and tungsten sulfide, and / or the second doping element is selected from one or more of nickel, molybdenum, tungsten, vanadium, chromium, copper, and platinum group metal elements; and / or

[0045] The method for preparing the light-emitting device further includes the steps of forming an electron functional layer between the cathode and the light-emitting layer; the material of the electron functional layer includes one or more of an undoped first inorganic compound and a doped second inorganic compound;

[0046] Wherein, the undoped first inorganic compound includes one or more of an undoped first metal oxide, a IIB-VIA group semiconductor material, a IIIA-VA group semiconductor material, and a IB-IIIA-VIA group semiconductor material. The undoped first metal oxide includes one or more of ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, and ZrO2, and / or the IIB-VIA group semiconductor material includes one or more of ZnS, ZnSe, and CdS, and / or the IIIA-VA group semiconductor material includes one or more of InP and GaP, and / or the IB-IIIA-VIA group semiconductor material includes one or more of CuInS and CuGaS;

[0047] And / or, the doped second inorganic compound includes a second metal oxide doped with a first doping element. The second metal oxide is selected from ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, or ZrO2, and the first doping element is selected from one or more of Mg, Ca, Zr, W, Ga, Li, Al, Ti, Y, In, and Sn.

[0048] In a third aspect, the present application provides an electronic device, which includes a light-emitting device as described in any one of the first aspect, or the electronic device includes a light-emitting device prepared by the preparation method as described in any one of the second aspect.

[0049] The present application provides a light-emitting device, a preparation method of the light-emitting device, and an electronic device, which have the following technical effects:

[0050] In the light-emitting device, the material of the light-emitting layer contains quantum dots with a core-shell structure. By regulating the average particle size of the core in the quantum dots and the thickness of the shell layer, the optoelectronic performance and device life of the light-emitting device can be improved. Applying the light-emitting device to an electronic device is beneficial to improving the display effect and service life of the electronic device. Description of the Drawings

[0051] The following will combine the drawings and describe the specific embodiments of the present application in detail, making the technical solutions and other beneficial effects of the present application obvious.

[0052] Figure 1 It is a schematic structural diagram of the first light-emitting device provided by the embodiment of the present application;

[0053] Figure 2 Schematic structural diagram of the second light-emitting device provided by the embodiment of the present application;

[0054] Figure 3 Schematic structural diagram of the third light-emitting device provided by the embodiment of the present application;

[0055] Figure 4 Schematic structural diagram of the fourth light-emitting device provided by the embodiment of the present application;

[0056] Figure 5 Schematic diagram of the contact relationship between the light-emitting layers formed by two kinds of quantum dots with different average particle sizes and the hole functional layer in the embodiment of the present application.

[0057] The reference numerals are as follows:

[0058] 1: Light-emitting device, 10: Substrate, 11: Anode, 12: Cathode, 13: Light-emitting layer, 14: Electron functional layer, 15: Hole functional layer, 130: Quantum dot, 131: First quantum dot layer, 132: Second quantum dot layer, 133: Third quantum dot layer, 151: Hole injection layer, 152: Hole transport layer. Detailed implementation manners

[0059] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present application.

[0060] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to the described content can be applied to the present invention. The preferred implementation methods and materials described herein are only for illustrative purposes and do not limit the content of the present application.

[0061] It should be noted that the order of description of the following embodiments does not limit the preferred order of the embodiments. Each embodiment of the present application may exist in a range form; it should be understood that the description in a range form is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present invention; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and single values within that 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., and single numbers within the counted range, such as 1, 2, 3, 4, 5, and 6, which applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0062] In the description of the present application, the term "comprising" means "including but not limited to".

[0063] The term "at least one" means one or more, and "a plurality" means two or more. The term "at least one", "at least one of the following (items)" or its similar expressions refer to any combination of these items, including any combination of single (item) or plural items (items). For example, "at least one of (item) a, b, or c" or "at least one of (item) a, b, and c" can both be expressed 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 or multiple respectively.

[0064] In the present application, the description of "layer A is formed on one side of layer B" or "layer A is formed on the side of layer B away from layer C" may mean that layer A is directly formed on one side of layer B or on the side of layer B away from layer C, that is, layer A is in direct contact with layer B; it may also mean that layer A is indirectly formed on one side of layer B or on the side of layer B away from layer C, that is, other film layers may be formed between layer A and layer B.

[0065] The selection range of the term "and / or" includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The said any and all combinations include combinations of any two related listed items, any more related listed items, or all related listed items. For example, "A and / or B" includes three parallel solutions: A, B, and A + B. Another example, for the technical solution of "A, and / or, B, and / or, C, and / or, D", it includes any one of A, B, C, D (that is, the technical solutions connected by "logical or"), and also includes any and all combinations of A, B, C, D, that is, it includes combinations of any two or any three of A, B, C, D, and also includes the four - item combination of A, B, C, D (that is, the technical solutions connected by "logical and").

[0066] The term "particle size" refers to the diameter of the nanoparticles.

[0067] Quantum dots are a kind of luminescent material with great potential. At present, although quantum dots already have efficient, stable and high color purity photoluminescence properties, it is still extremely challenging to fully transfer these excellent properties to electroluminescent devices. This is because there are problems of unbalanced carrier transport and interfacial exciton quenching in QLED devices. Especially in blue QLED devices, the hole injection level is much lower than the electron injection level, which limits the improvement of the optoelectronic performance and device lifetime of QLED devices.

[0068] Based on this, the present application provides a light-emitting device, by controlling the average particle size of the core of the quantum dots and the thickness of the shell of the quantum dots, to improve the matching degree between the hole injection level and the electron injection level, promote the balance of carrier transport, and thus improve the optoelectronic performance and device lifetime of the light-emitting device.

[0069] As Figure 1 shown, the light-emitting device 1 includes an anode 11, a cathode 12 and a light-emitting layer 13. Among them, the anode 11 and the cathode 12 are arranged opposite to each other, and the light-emitting layer 13 is arranged between the anode 11 and the cathode 12. Among them, the material of the light-emitting layer 13 contains quantum dots with a core-shell structure, the average particle size of the core of the quantum dots is less than 5 nm, and the thickness of the shell of the quantum dots is less than 2.5 nm.

[0070] Among them, the average conduction band energy level of the shell of the quantum dots is Ec1, the conduction band energy level of the core of the quantum dots is Ec2, and the difference between Ec1 and Ec2 is not greater than 0.2 eV, for example, not greater than 0.18 eV, not greater than 0.15 eV, not greater than 0.12 eV, or not greater than 0.1 eV; the average valence band energy level of the shell of the quantum dots is Ev1, the valence band energy level of the core of the quantum dots is Ev2, and the difference between Ev2 and Ev1 is not less than 0.8 eV, for example, not less than 0.85 eV, not less than 0.9 eV, not less than 0.95 eV, not less than 1.0 eV, or not less than 1.5 eV. In at least one embodiment of the present application, the difference between Ev2 and Ev1 is 0.8 eV to 1.0 eV.

[0071] It should be noted that when the shell of the quantum dots is a single-layer structure, the thickness of the shell of the quantum dots is the thickness of the single-layer shell. When the shell of the quantum dots is a multi-layer structure, the thickness of the shell of the quantum dots is the sum of the thicknesses of all the shells, and the calculation method of the average conduction band energy level of the shell of the quantum dots is: first calculate the percentage D i % of the thickness of each shell in the total thickness of the shell, and then multiply the conduction band energy level Ec i of each shell by the corresponding D i % to obtain A i , sum up the A iTo obtain A, the average conduction band energy level of the shell of the quantum dots is the value obtained by dividing A by the number of shells. Similarly, the average valence band energy level of the shell of the quantum dots is calculated.

[0072] Among them, the average particle size of the core of the quantum dots can be less than 4.8 nm, less than 4 nm, less than 3 nm, less than 2 nm, or less than 1.5 nm; in some embodiments of the present application, the average particle size of the core of the quantum dots is 1 nm to 4 nm, for example, it can be 1 nm, 2 nm, 3 nm, 4 nm or a value between any two of the foregoing values. The thickness of the shell of the quantum dots can be less than 2.5 nm, less than 2 nm, less than 1.5 nm, or less than 1.0 nm; in some embodiments of the present application, the thickness of the quantum dots is 1 nm to 2.5 nm, for example, it can be 1 nm, 1.5 nm, 2 nm, 2.5 nm or a value between any two of the foregoing values.

[0073] The quantum dots include but are not limited to one or more of red quantum dots, green quantum dots, and blue quantum dots. In order to further improve the comprehensive performance of the light-emitting device, in some embodiments of the present application, the average particle size of the quantum dots is 2 nm to 25 nm, for example, it can be 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 15 nm, 20 nm, 22 nm, 25 nm or a value between any two of the foregoing values.

[0074] In some embodiments of the present application, the material of the core of the quantum dot and the material of the shell of the quantum dot are independently selected from one or more of II-VI group compounds, III-VI group compounds, III-V group compounds, IV-VI group compounds, and I-III-VI group compounds. Among them, the II-VI group compounds include, but are not limited to, one or more of 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, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the III-VI group compounds include, but are not limited to, one or more of In2S3, In2Se3, InGaS3, and InGaSe3; the III-V group compounds include, but are not limited to, one or more of 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, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the IV-VI group compounds include, but are not limited to, one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; the I-III-VI group compounds include, but are not limited to, one or more of AgInS, AgInS2, CuInS, CuInS2, AgGaS2, CuGaS2, CuGaO2, AgGaO2, AgAlO2, AgInGaS2, and CuInGaS2.

[0075] As an example, the quantum dots are selected from any one of the following:

[0076] (1) Zn x1 Cd (1-x1) Se / ZnSe / Cd x2 Zn (1-x2) S / ZnS, 0.85 ≤ x1 ≤ 0.95, 0.1 ≤ x2 ≤ 0.5;

[0077] (2) Zn y1 Cd (1-y1) Se / ZnSe / ZnS / Cd y2 Zn (1-y2) S / ZnS, 0.85 ≤ y1 ≤ 0.95, 0.1 ≤ y2 ≤ 0.5;

[0078] (3) Zn z1 Cd (1-z1) Se / Cd z2 Zn (1-z2) S / ZnS, 0.85 ≤ z1 ≤ 0.95, 0.1 ≤ z2 ≤ 0.5;

[0079] (4) Cd t1 Zn (1- t1) Se / ZnSe t2 S (1-t2) / Cd t3 Zn (1-t3) S / ZnS, 0.85 ≤ t1 ≤ 0.95, 0.4 ≤ t2 ≤ 1, 0.1 ≤ t3 ≤ 0.5;

[0080] (5) Cd r1 Zn (1- r1) Se / ZnSe / Cd r2 Zn (1-r2) S, 0.85 ≤ r1 ≤ 0.95, 0.1 ≤ r1 ≤ 0.3.

[0081] In order to improve the solution processability of the quantum dots and enhance the luminous efficiency of the light-emitting device 1, in some embodiments of the present application, a ligand is further connected to the surface of the quantum dots. The ligand can be a ligand common in the art, including but not limited to aliphatic carboxylic acid ligands of C1-C 30 aromatic carboxylic acid ligands of C6-C 30 aliphatic thiol ligands of C1-C 30 thiol aromatic ligands of C6-C 30 aliphatic amine ligands of C1-C 30 aromatic amine ligands of C6-C 30 aliphatic phosphine ligands of C1-C 30 aromatic phosphine ligands of C6-C30 aromatic phosphine ligands and C6-C 30 one or more of aromatic phosphate ligands and halogen ligands.

[0082] Among them, the C1-C 30 aliphatic carboxylic acid ligands include but are not limited to one or more of octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, eicosanoic acid, tetracosanoic acid, hexacosanoic 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, dibenzoic acid, and 1-naphthoic acid. C1-C 30 aliphatic thiol ligands include but are not limited to one or more of hexanethiol, octanethiol, nonanethiol, decanethiol, undecanethiol, dodecanethiol, hexadecanethiol, and octadecanethiol, C6-C 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 aliphatic amine ligands include but are not limited to one or more of hexylamine, octylamine, dioctylamine, trioctylamine, nonylamine, decylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, and oleylamine, C6-C 30 aromatic amine ligands include but are not limited to one or more of aniline, indanpropylamine, 4-octylaniline, and benzidine. C1-C 30 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-C 30 aromatic phosphine ligands include but are not limited to one or more of bis(2-diphenylphosphinoethyl)phenylphosphine and triphenylphosphine oxide, C6-C 30 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.

[0083] In some embodiments of the present application, the light-emitting layer 13 includes N quantum dot layers, the materials of each quantum dot layer are independently selected from any one of the aforementioned quantum dots, and the quantum dots in each quantum dot layer are arranged in a single layer, where N is a positive integer greater than or equal to 1. It can be understood that N can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 18, 20, etc.

[0084] In some embodiments of the present application, such asFigure 2 As shown, N is 1, the light-emitting layer 13 is a quantum dot layer, and the quantum dots in the light-emitting layer 13 are arranged in a single layer.

[0085] In some other embodiments of the present application, such as Figure 3 As shown, N is 2, the light-emitting layer 13 is composed of a first quantum dot layer 131 and a second quantum dot layer 132 arranged in a stack. The materials of the first quantum dot layer 131 and the second quantum dot layer 132 are independently selected from any one of the foregoing quantum dots. Moreover, the quantum dots in the first quantum dot layer 131 are arranged in a single layer, and the quantum dots in the second quantum dot layer 132 are arranged in a single layer.

[0086] In some other embodiments of the present application, such as Figure 4 As shown, N is 3, the light-emitting layer is composed of a first quantum dot layer 131, a second quantum dot layer 132, and a third quantum dot layer 133 arranged in a stack in sequence. The materials of the first quantum dot layer 131 to the third quantum dot layer 133 are independently selected from any one of the foregoing quantum dots. Moreover, the quantum dots in the first quantum dot layer 131 are arranged in a single layer, the quantum dots in the second quantum dot layer 132 are arranged in a single layer, and the quantum dots in the third quantum dot layer 133 are arranged in a single layer.

[0087] In order to balance the improvement of the comprehensive performance of the light-emitting device and the reduction of the manufacturing cost of the light-emitting device, in some embodiments of the present application, the thickness of the light-emitting layer 13 is 2 nm to 60 nm. For example, it can be 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, or a value between any two of the foregoing values.

[0088] In some embodiments of the present application, the materials of the anode 11 and the cathode 12 are independently selected from one or more of metals, carbon materials, and third metal oxides. Among them, 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 third metal oxide can be doped or undoped. The doped third 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 third metal oxides include, but are not limited to, one or more of TiO2, SnO2, ZnO, and In2O3.

[0089] It should be noted that the anode 11 and the cathode 12 can also be composite electrodes respectively. The composite electrode has a structure similar to a "sandwich", and the materials of the upper layer and the bottom layer are doped or undoped third metal oxides respectively, and the material of the middle layer is a metal. Examples include 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 thicknesses of the anode 11 and the cathode 12 are, for example, independently selected from 20 nm to 300 nm.

[0090] In order to further improve the comprehensive performance of the light-emitting device 1, in some embodiments of the present application, continue to refer to Figures 1 to 4 , the light-emitting device further includes an electron functional layer 14, and the electron functional layer 14 is disposed between the cathode 12 and the light-emitting layer 13; the thickness of the electron functional layer 14 is, for example, 10 nm to 200 nm. The electron functional layer 14 can be a single-layer structure or a multi-layer structure; when the electron functional layer 14 is a multi-layer structure, the electron functional layer 14 includes, for example, one or more of an electron injection layer, an electron transport layer, and a hole blocking layer. For the electron functional layer 14 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 than the hole blocking layer, and the hole blocking layer is closer to the light-emitting layer 13 than the electron injection layer.

[0091] Among them, the electron functional layer 14 includes one or more of an undoped first inorganic compound and a doped second inorganic compound. Among them, the undoped first inorganic compound includes one or more of an undoped first metal oxide, a IIB-VIA group semiconductor material, a IIIA-VA group semiconductor material, and a IB-IIIA-VIA group semiconductor material. The undoped first metal oxide includes, but is not limited to, one or more of ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, and ZrO2, and / or the IIB-VIA group semiconductor material includes, but is not limited to, one or more of ZnS, ZnSe, and CdS, and / or the IIIA-VA group semiconductor material includes, but is not limited to, one or more of InP and GaP, and / or the IB-IIIA-VIA group semiconductor material includes, but is not limited to, one or more of CuInS and CuGaS.

[0092] The doped second inorganic compound includes a second metal oxide doped with a first doping element. The second metal oxide includes, but is not limited to, one or more of ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, and ZrO2. The first doping element includes, but is not limited to, one or more of Mg, Ca, Zr, W, Ga, Li, Al, Ti, Y, In, and Sn. The molar percentage of the first doping element in the doped second inorganic compound is, for example, not higher than 5%, not higher than 10%, not higher than 20%, not higher than 30%, or not higher than 50%. The doped second inorganic compound includes, but is not limited to, one or more of magnesium zinc oxide, calcium zinc oxide, zinc zirconium oxide, gallium zinc oxide, aluminum zinc oxide, lithium zinc oxide, titanium zinc oxide, yttrium zinc oxide, indium tin oxide, and lithium titanium oxide. An example is Zn (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 O, and one or more of them, where 0 < x ≤ 0.5.

[0093] It should be noted that when the electronic functional layer 14 includes multiple materials and the electronic functional layer 14 is a multi-layer structure, the multiple materials can all be in the same layer, or in different layers respectively, or some in the same layer. As an example, as Figures 1 to 4 shown, the electronic functional layer 14 is a single-layer structure, and the electronic functional layer 14 is an electron transport layer.

[0094] In order to further improve the optoelectronic performance and device life of the light-emitting device 1, in some embodiments of the present application, continue to refer to Figures 1 to 4, the light-emitting device 1 further includes a hole functional layer 15 disposed between the anode 11 and the light-emitting layer 13. The hole functional layer 15 may be a single-layer structure or a multi-layer structure. The hole functional layer 15 includes, for example, one or more of a hole injection layer, a hole transport layer, and an electron blocking layer. For the hole functional layer 15 including a hole injection layer, a hole transport layer, and an electron blocking layer, the hole injection layer, the hole transport layer, and the electron blocking layer may be sequentially disposed, and the hole injection layer is closer to the anode 11 than the electron blocking layer. The thickness of the hole functional layer 15 is, for example, 10 nm to 200 nm.

[0095] Among them, the materials of the hole functional layer 15 include, but are not limited to, one or more of an undoped third inorganic compound, a doped fourth inorganic compound, and an organic compound. Among them, the organic compounds include, but are not limited to, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (abbreviation: PEDOT:PSS, CAS No. 155090-83-8), copper phthalocyanine (CAS No. 147-14-8), titanium oxyphthalocyanine (CAS No. 26201-32-1), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane (CAS No. 29261-33-4), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (CAS No. 105598-27-4), polyaniline (CAS No. 25233-30-1), polypyrrole (CAS No. 30604-81-0), 3-hexyl-substituted polythiophene (CAS No. 104934-50-1), poly(9-vinylcarbazole) (abbreviation: PVK, CAS No. 25067-59-8), 4,4'-bis(9-carbazolyl)biphenyl (abbreviation: CBP, CAS No. 58328-31-7), poly[bis(4-phenyl)(4-butylphenyl)amine], 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] (abbreviation: TAPC, CAS No. 58473-78-2), poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine)] (abbreviation: TFB, CAS No. 220797-16-0), poly[(N,N'-(4-n-butylphenyl)-N,N'-diphenyl-1,4-phenylenediamine)-ALT-(9,9-din-octylfluorenyl-2,7-diyl)] (CAS No. 223569-31-1), 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (CAS No. 124729-98-2), 4,4',4”-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA, CAS No. 139092-78-7), 4,4',4'-tris(2-naphthylphenylamino)triphenylamine (CAS No. 185690-41-9), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (abbreviation: NPB, CAS No. 123847-85-8), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (abbreviation: TPD, CAS No. 65181-78-4), N,N'-bis[4-(diphenylamino)phenyl]-N,N'-diphenylbenzidine (CAS No. 209980-53-0), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-9,9-spirobifluorene-2,7-diamine (abbreviation: Spiro-TPD,One or more of: 10-(4-(diphenylamino)phenyl)-2-(4-(naphthalen-1-yl)phenyl)-9,9'-spirobi[9H-fluorene] (CAS No. 1033035-83-4), N2,N7-di-1-naphthyl-N2,N7-diphenyl-9,9'-spirobi[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'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (abbreviated as Spiro-omeTAD, CAS No. 207739-72-8); and / or, the non-doped third inorganic compound includes but is not limited to one or more of graphene, C60, nickel oxide (such as NiO), molybdenum oxide (such as MoO3), tungsten oxide (such as WO3), vanadium oxide (such as V2O5), p-type gallium nitride, chromium oxide (such as Cr2O3), copper oxide (such as CuO or Cu2O), copper sulfide (such as CuS), molybdenum sulfide (such as MoS2), and tungsten sulfide (such as WS2); and / or, the doped fourth inorganic compound is a host inorganic compound doped with a second doping element, and the host inorganic compound includes but is not limited to one or more of graphene, C60, nickel oxide (such as NiO), molybdenum oxide (such as MoO3), tungsten oxide (such as WO3), vanadium oxide (such as V2O5), p-type gallium nitride, chromium oxide (such as Cr2O3), copper oxide (such as CuO or Cu2O), copper sulfide (such as CuS), molybdenum sulfide (such as MoS2), and tungsten sulfide (such as WS2), and / or the second doping element includes but is not limited to one or more of nickel, molybdenum, tungsten, vanadium, chromium, copper, and platinum group metal elements.,

[0096] It can be understood that when the hole functional layer 15 contains multiple materials and the hole functional layer 15 is a multi-layer structure, the multiple materials may all be in the same layer, or in different layers respectively, or partially in the same layer. For example, as Figures 2 to 4 shown, when the hole functional layer 15 is composed of a hole injection layer and a hole transport layer arranged in a stack, the materials of the hole functional layer 15 include PEDOT:PSS and TFB, and PEDOT:PSS and TFB are in different layers respectively. The material of the hole injection layer is PEDOT:PSS, and the material of the hole transport layer is TFB.

[0097] It should be noted that the applicant has found that for QLED, the use of organic compounds as materials for the hole functional layer and inorganic compounds as materials for the electron functional layer has better QLED performance. However, the hole mobility of the organic compound is low, and the valence band energy level of the light-emitting layer is deep, which makes the injection barrier between the light-emitting layer and the hole functional layer large, resulting in poor hole injection level; in addition, the inorganic compound is mostly N-type metal oxide (such as ZnO), and the quantum dot itself is also an N-type semiconductor, so the transmission ability of electrons is much stronger than the transmission ability of holes, resulting in the hole level in the light-emitting layer being significantly lower than the electron level, thereby limiting the improvement of QLED performance and life.

[0098] It is understandable that since the N-type metal oxides in the electronic functional layer are mostly in the form of nanoparticles, and the quantum dots themselves are also in the form of nanoparticles, and in practical applications, the average particle size of the N-type metal oxides is usually not higher than the average particle size of the quantum dots, the change in the particle size of the quantum dots has little effect on the interface contact between the light-emitting layer and the electronic functional layer, that is, the difference in electron injection is not obvious. However, for the interface between the light-emitting layer and the hole functional layer (the material is an organic compound), the greater the phase difference between the contact points between quantum dots of different particle sizes and the hole functional layer, such as Figure 5 As shown, the smaller the particle size of the quantum dots 130 is, the more contact points there are between the quantum dots 130 in the light-emitting layer 13 and the hole functional layer 15, and the easier it is for holes to enter the light-emitting layer 13. However, the easier it is for electrons in the light-emitting layer 13 to enter the hole functional layer 15, which will destroy the interface balance between the light-emitting layer 13 and the hole functional layer 15.

[0099] Furthermore, in the light-emitting layer, the shorter the electron scattering path, the faster the electron transmission speed, and the electron scattering path is related to the number of quantum dots arranged in a single layer in the light-emitting layer. It can be understood that when the number of quantum dots arranged in a single layer in the light-emitting layer is a fixed value, the interface balance between the light-emitting layer and the hole functional layer is directly related to the average particle size of the quantum dots. When the average particle size of the quantum dots in the light-emitting layer is a fixed value, the more quantum dots are arranged in a single layer, the longer the electron scattering path, the slower the electron transmission speed, the less likely it is to enter the hole functional layer, and the slower the speed at which electrons destroy the interface balance between the light-emitting layer and the hole functional layer. When the overall size of the light-emitting layer is a fixed value, continue to refer to Figure 5 The smaller the average particle size of the quantum dots 130 is, the more layers of the quantum dots 130 arranged in a single layer are.

[0100] Based on this, in order to balance the improvement of the hole injection level and reduce the damage to the interface balance between the electron and the hole functional layer, it is necessary to control the balance between the average particle size of the quantum dots and the number of layers of the quantum dots arranged in a single layer in the light-emitting layer. In addition, compared with using quantum dots with a smaller average particle size as the material of the light-emitting layer, using quantum dots with a larger average particle size as the material of the light-emitting layer will improve the electron injection level and the hole injection level of the light-emitting device to varying degrees; too thick a thickness of the shell of the quantum dots will also have a negative impact on the light-emitting efficiency, even if the hole injection level can be improved, there will also be a problem of a decrease in the number of converted radiation photons. Therefore, it is necessary to comprehensively regulate the balance between the size of the core of the quantum dots, the thickness of the shell of the quantum dots, and the number of layers of the quantum dots arranged in a single layer in the light-emitting layer, so as to effectively improve the optoelectronic performance and device life of the QLED.

[0101] The embodiment of the present application also provides a method for manufacturing a light-emitting device, which can be used to manufacture any one of the foregoing light-emitting devices. The method for manufacturing the light-emitting device includes the following steps:

[0102] S1. Provide a bottom electrode and form a light-emitting layer on one side of the bottom electrode;

[0103] S2. Form a top electrode on the side of the light-emitting layer away from the bottom electrode.

[0104] Among them, one of the bottom electrode and the top electrode is an anode, and the other is a cathode. The material of the light-emitting layer includes quantum dots with a core-shell structure. The average particle size of the core of the quantum dots is less than 5 nm, and the thickness of the shell of the quantum dots is less than 2.5 nm.

[0105] Among them, the average conduction band energy level of the shell of the quantum dots is Ec1, the conduction band energy level of the core of the quantum dots is Ec2, and the difference between Ec1 and Ec2 is not greater than 0.2 eV, such as not greater than 0.18 eV, not greater than 0.15 eV, not greater than 0.12 eV, or not greater than 0.1 eV; the average valence band energy level of the shell of the quantum dots is Ev1, the valence band energy level of the core of the quantum dots is Ev2, and the difference between Ev2 and Ev1 is not less than 0.8 eV, such as not less than 0.85 eV, not less than 0.9 eV, not less than 0.95 eV, not less than 1.0 eV, or not less than 1.5 eV. In at least one embodiment of the present application, the difference between Ev2 and Ev1 is 0.8 eV to 1.0 eV.

[0106] In order to simplify the manufacturing process of the light-emitting device, in some embodiments of the present application, the method for forming the light-emitting layer includes the following steps:

[0107] S11. Deposit a dispersion liquid containing quantum dots to obtain a first film layer;

[0108] S12. Dry the first film layer to obtain a light-emitting layer.

[0109] Among them, the first film layer includes N quantum dot layers. The material of each quantum dot layer is any one of the aforementioned quantum dots, and the quantum dots in each quantum dot layer are arranged in a single layer. N is a positive integer greater than or equal to 1. The number of formed quantum dot layers is controlled by adjusting the concentration of the quantum dots in the dispersion liquid. For the dispersion liquid with the same volume, the higher the concentration of the quantum dots, the more the number of formed quantum dot layers.

[0110] In some other embodiments of the present application, the relationship between the number of formed quantum dot layers and the concentration of quantum dots in the dispersion liquid is as follows:

[0111] (B1) N is 1, and the concentration of quantum dots in the dispersion liquid is 5 mg / mL to 7 mg / mL;

[0112] (B2) N is 2, and the concentration of the quantum dots in the dispersion liquid is 21 mg / mL to 24 mg / mL;

[0113] (B3) N is 3, and the concentration of the quantum dots in the dispersion liquid is 28 mg / mL to 32 mg / mL.

[0114] Among them, for (B1), the concentration of quantum dots in the dispersion liquid can be, for example, 5 mg / mL, 6 mg / mL, 7 mg / mL, or a value between any two of the aforementioned values.

[0115] For (B2), the concentration of quantum dots in the dispersion liquid can be, for example, 21 mg / mL, 22 mg / mL, 23 mg / mL, 24 mg / mL, or a value between any two of the aforementioned values.

[0116] For (B3), the concentration of quantum dots in the dispersion liquid can be, for example, 28 mg / mL, 29 mg / mL, 30 mg / mL, 31 mg / mL, 32 mg / mL, or a value between any two of the aforementioned values.

[0117] Continuing with step S1, the dispersant of the dispersion is an organic compound in which quantum dots have good dispersion performance, including but not limited to one or more of alkanes, aromatic hydrocarbons, halogenated alkanes, alcohol compounds, ether compounds, furan compounds, pyridine compounds, amide compounds, ester compounds, and sulfone compounds. Among them, alkanes include but are not limited to one or more of nonane, decane, dodecane, terpane, butylcyclohexane, n-octane, n-hexane, n-heptane, n-nonane, n-decane, cyclohexane, and cyclopentane; aromatic hydrocarbons include but are not limited to one or more of diethylbenzene, mesitylene, propylbenzene, isopropylbenzene, p-cumene, butylbenzene, and 1-methylnaphthalene or indene; halogenated alkanes include but are not limited to one or more of dichloromethane, chloroform, and carbon tetrachloride; alcohol compounds include but are not limited to one or more of methanol, ethanol, propanol, butanol, ethylene glycol, and glycerol; ether compounds include but are not limited to ethylene glycol monomethyl ether; furan compounds include but are not limited to tetrahydrofuran; pyridine compounds include but are not limited to pyridine; amide compounds include but are not limited to N,N-dimethylformamide; sulfone compounds include but are not limited to dimethyl sulfoxide; the general formula of ester compounds is R1COOR2, where R1 and R2 are independently selected from alkyl groups with 1 to 20 carbon atoms, alkyl groups with 1 to 10 carbon atoms, or alkyl groups with 1 to 6 carbon atoms. For example, R1 and R2 are independently selected from methyl, ethyl, propyl, or butyl, and examples of ester compounds are one or more of methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, and methyl propionate.

[0118] Continuing with step S1, the deposition methods of the dispersion include but are not limited to one or more of spin coating, printing, inkjet printing, blade coating, printing, dip coating, immersion, spraying, roll coating, casting, slot die coating, bar coating, and solution electrodeposition.

[0119] In step S2, the "drying treatment" includes all processes that can make the first film layer obtain higher energy and solidify into a film, including but not limited to one or more of natural air drying treatment, heat treatment, vacuum drying treatment, laser annealing treatment, electron beam annealing treatment, atomic annealing treatment, and microwave irradiation annealing treatment. Among them, the temperature of the heat treatment can be constant or non-constant (for example, the temperature changes in a gradient). As an example, the drying treatment is a heat treatment, and the temperature of the heat treatment is 60°C to 150°C.

[0120] In order to further improve the comprehensive performance of the light-emitting device, in some embodiments of the present application, the method for manufacturing the light-emitting device further includes the step of forming a hole functional layer between the anode and the light-emitting layer. The structural composition of the hole functional layer refers to the description above. That is, when the light-emitting device is of a normal structure, the bottom electrode is the anode and the top electrode is the cathode. Before the step of forming the light-emitting layer on one side of the bottom electrode, the method for manufacturing the light-emitting device further includes the step of forming a hole functional layer on one side of the bottom electrode; the light-emitting layer is formed on the side of the hole functional layer away from the bottom electrode. When the light-emitting device is of an inverted structure, the bottom electrode is the cathode and the top electrode is the anode. Before step S2, the method for manufacturing the light-emitting device further includes the step of forming a hole functional layer on the side of the light-emitting layer away from the bottom electrode; the top electrode is formed on the side of the hole functional layer away from the light-emitting layer.

[0121] In order to further improve the comprehensive performance of the light-emitting device, in some embodiments of the present application, the method for manufacturing the light-emitting device further includes the step of forming an electron functional layer between the cathode and the light-emitting layer. The structural composition of the electron functional layer refers to the description above. That is, when the light-emitting device is of a normal structure, the bottom electrode is the anode and the top electrode is the cathode. Before step S2, the method for manufacturing the light-emitting device further includes the step of forming an electron functional layer on the side of the light-emitting layer away from the bottom electrode; the top electrode is formed on the side of the electron functional layer away from the light-emitting layer. When the light-emitting device is of an inverted structure, the bottom electrode is the cathode and the top electrode is the anode. Before the step of forming the light-emitting layer on one side of the bottom electrode, the method for manufacturing the light-emitting device further includes the step of forming an electron functional layer on one side of the bottom electrode; the light-emitting layer is formed on the side of the electron functional layer away from the bottom electrode.

[0122] It should be noted that, in addition to the light-emitting layer, the preparation methods of other functional film layers in the light-emitting device include, but are not limited to, chemical methods and / or physical methods. Among them, the chemical methods include, but are not limited to, one or more of chemical vapor deposition method, sequential ionic layer adsorption and reaction method, anodic oxidation method, electrolytic deposition method, and coprecipitation method. The physical methods include, but are not limited to, physical coating method and solution method. The physical coating method includes, but is not limited to, one or more of thermal evaporation coating method, electron beam evaporation coating method, magnetron sputtering method, multi-arc ion coating method, physical vapor deposition method, atomic layer deposition method, and pulsed laser deposition method. The solution method includes, but is not limited to, one or more of spin coating method, printing method, inkjet printing method, blade coating method, printing method, dip coating method, immersion method, spraying method, roll coating method, casting method, slot die coating method, and bar coating method. When forming the functional film layer by the solution method, a drying treatment process needs to be added to convert the wet film into a cured film. The drying treatment process includes, but is not limited to, heat treatment, vacuum drying treatment, air drying treatment, etc. Among them, for the functional film layer (the material is an inorganic compound, especially inorganic nanoparticles) located above the light-emitting layer, after forming the cured film by using low-temperature (the temperature is not higher than 80 °C) drying treatment processes such as vacuum drying treatment and air drying treatment, in order to further improve the film-forming quality, the cured film can be further annealed by using processes that can control the annealing depth, such as pulsed laser annealing, electron beam annealing, atomic annealing, and infrared irradiation annealing.

[0123] After preparing each functional film layer of the light-emitting device, a packaging treatment process is also required. The packaging treatment can be carried out by using common machine packaging or manual packaging. In the environment of the packaging treatment, the oxygen content and the water content are both lower than 0.1 ppm to ensure the stability of the light-emitting device.

[0124] The embodiments of the present application also provide an electronic device, which includes any one of the light-emitting devices described in the embodiments of the present application, or the electronic device includes a light-emitting device prepared by any one of the preparation methods described in the embodiments of the present application. The electronic device can be, for example, any electronic product with a display function, including but not limited to a smartphone, a tablet personal computer, a mobile phone, a video telephone, an e-book reader, a laptop PC, a netbook computer, a workstation, a server, a personal digital assistant, a portable multimedia player, an MP3 player, a mobile medical device, a camera, a game console, a digital camera, a car navigation device, an electronic billboard, an automated teller machine, a smart bracelet, a smart watch, a Virtual Reality (VR) device or a wearable device.

[0125] The technical solutions and technical effects of the present application will be described in detail below through specific examples, comparative examples and experimental examples. The following examples are only partial examples of the present application and do not specifically limit the present application.

[0126] Example 1

[0127] This example provides a light-emitting device and a preparation method thereof. The light-emitting device is a quantum dot light-emitting diode with a normal structure. As Figure 2 shown, in the direction from bottom to top, the light-emitting device 1 includes a substrate 10, an anode 11, a hole functional layer 15, a light-emitting layer 13, an electron functional layer 14 and a cathode 12 which are sequentially stacked. Among them, the hole functional layer 15 is composed of a hole injection layer 151 and a hole transport layer 152 which are stacked. The hole injection layer 151 is closer to the anode 11 than the hole transport layer 152; the electron functional layer 14 is a single-layer structure; the light-emitting layer 13 is a quantum dot layer, and the quantum dots in the quantum dot layer are arranged in a single layer.

[0128] The materials and thicknesses of each layer in the light-emitting device 1 are as follows:

[0129] The material of the substrate 10 is glass, and the thickness of the substrate 10 is 2 mm;

[0130] The material of the anode 11 is ITO, and the thickness of the anode 11 is 50 nm;

[0131] The material of the cathode 12 is Ag, and the thickness of the cathode 12 is 100 nm;

[0132] The material of the light-emitting layer 13 is blue quantum dots Cd 0.08 Zn 0.92 Se / ZnSe / Cd 0.6 Zn 0.4 S. Among them, the average particle size of the quantum dot core Cd 0.08 Zn 0.92 Se is 4 nm, the thickness of the middle shell layer ZnSe is 1 nm, and the thickness of the outer shell Cd 0.6 Zn 0.4 S is 0.5 nm; the difference between Ec1 and Ec2 is 0.2 eV, and the difference between Ev2 and the said Ev1 is 1.0 eV.

[0133] The material of the electron functional layer 14 is Zn 0.85 Mg 0.15 O (average particle size is 4 nm), and the thickness is 40 nm;

[0134] The material of the hole injection layer 151 is PEDOT:PSS, and the thickness of the hole injection layer 151 is 25 nm;

[0135] The material of the hole transport layer 152 is PVK, and the thickness of the hole transport layer 152 is 25 nm.

[0136] The preparation method of the light-emitting device in this embodiment includes the following steps:

[0137] S1.1. Provide a substrate, sputter ITO on one side of the substrate to obtain an ITO layer, wipe the surface of the ITO layer with a cotton swab dipped in a small amount of soapy water to remove visible impurities on the surface, and then ultrasonically clean the substrate including ITO in deionized water for 15 min, in acetone for 15 min, in ethanol for 15 min, and in isopropanol for 15 min in sequence. After drying, perform ultraviolet-ozone surface treatment for 20 min to obtain a substrate including an anode;

[0138] S1.2. In an air environment at normal temperature and pressure, spin-coat an aqueous solution of PEDOT:PSS with a mass fraction of 2.8% on the side of the anode away from the substrate, and then place it in a constant temperature heat treatment at 150 °C to solidify into a film to obtain a hole injection layer;

[0139] S1.3. In a nitrogen environment at normal temperature and pressure, 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 in a constant temperature heat treatment at 150 °C to solidify into a film to obtain a hole transport layer;

[0140] S1.4. Under a nitrogen environment at normal temperature and pressure, spin-coat a blue quantum dot - n-octane solution with a concentration of 7 mg / mL on the side of the hole transport layer away from the hole injection layer at a spin-coating speed of 2000 r / min for 15 s, and then place it in a constant temperature heat treatment at 80 °C to cure into a film, obtaining a light-emitting layer, where the blue quantum dots in the light-emitting layer are arranged in a single layer;

[0141] S1.5. Under a nitrogen environment at normal temperature and pressure, spin-coat a nano-ZnO - ethanol solution with a concentration of 30 mg / mL on the side of the light-emitting layer away from the hole transport layer, and then place it in a constant temperature heat treatment at 80 °C to cure into a film, obtaining an electron functional layer;

[0142] S1.6. Place the stacked structure completed in step S1.5 in an evaporation chamber with a vacuum degree not higher than 3×10 -4 Pa, thermally evaporate Ag on the side of the electron functional layer away from the light-emitting layer through a mask plate to obtain a cathode, and then encapsulate to obtain a light-emitting device.

[0143] Example 2

[0144] This example provides a light-emitting device and a preparation method thereof. Compared with the light-emitting device in Example 1, the difference in the light-emitting device in this example is that: as Figure 3 shown, the light-emitting layer 13 is composed of a first quantum dot layer 131 and a second quantum dot layer 132. The materials of the first quantum dot layer 131 and the second quantum dot layer 132 are both the blue quantum dots in Example 1; the blue quantum dots in the first quantum dot layer 131 are arranged in a single layer, and the blue quantum dots in the second quantum dot layer 132 are arranged in a single layer.

[0145] Compared with the preparation method of the light-emitting device in Example 1, the difference in the preparation method of the light-emitting device in this example is that: replace step S1.4 with "Under a nitrogen environment at normal temperature and pressure, spin-coat a blue quantum dot - n-octane solution with a concentration of 24 mg / mL on the side of the hole transport layer away from the hole injection layer at a spin-coating speed of 2000 r / min for 15 s, and then place it in a constant temperature heat treatment at 80 °C to cure into a film, obtaining a light-emitting layer composed of a stacked first quantum dot layer and a second quantum dot layer".

[0146] Example 3

[0147] This example provides a light-emitting device and a preparation method thereof. Compared with the light-emitting device in Example 1, the difference in the light-emitting device in this example is that: as Figure 4As shown, the light-emitting layer 13 is composed of a first quantum dot layer 131, a second quantum dot layer 132, and a third quantum dot layer 133. The materials of the first quantum dot layer 131 to the third quantum dot layer 133 are all the blue quantum dots in Example 1. The blue quantum dots are arranged in a single layer in the first quantum dot layer 131, in a single layer in the second quantum dot layer 132, and in a single layer in the third quantum dot layer 133.

[0148] Compared with the preparation method of the light-emitting device in Example 1, the difference in the preparation method of the light-emitting device in this example is that: step S1.4 is replaced with "spin-coating a blue quantum dot - n-octane solution with a concentration of 32 mg / mL on the side of the hole transport layer away from the hole injection layer under a nitrogen environment at normal temperature and pressure, with a spin-coating speed of 2000 r / min and a spin-coating time of 15 s, and then placing it in a constant temperature heat treatment at 80 °C to cure into a film, obtaining a light-emitting layer composed of a first quantum dot layer to a third quantum dot layer stacked in sequence".

[0149] Example 4

[0150] This example provides a light-emitting device and its preparation method. Compared with the light-emitting device in Example 1, the difference in the light-emitting device in this example is that: the material of the light-emitting layer is replaced with "blue quantum dot Cd 0.08 Zn 0.92 Se / ZnSe 0.2 S 0.8 / Cd 0.6 Zn 0.4 S / ZnS", where the average particle size of the quantum dot core Cd 0.08 Zn 0.92 Se is 4 nm, the thickness of the first shell layer ZnSe 0.2 S 0.8 is 1 nm, the thickness of the second shell layer Cd 0.6 Zn 0.4 S is 0.5 nm, and the thickness of the outer shell ZnS is 0.5 nm; the difference between Ec1 and Ec2 is 0.2 eV, and the difference between Ev2 and the said Ev1 is 0.8 eV.

[0151] The preparation method of the light-emitting device in this example is carried out with reference to Example 1.

[0152] Example 5

[0153] This example provides a light-emitting device and its preparation method. Compared with the light-emitting device in Example 1, the difference in the light-emitting device in this example is that: the material of the light-emitting layer is replaced with "blue quantum dot Cd 0.08 Zn 0.92 Se / ZnSe 0.2 S 0.8 / Cd 0.6 Zn 0.4 S / ZnS”, where the average particle size of the quantum dot core Cd 0.08 Zn 0.92 Se is 4 nm, the thickness of the first shell layer ZnSe 0.2 S 0.8 is 1 nm, the thickness of the second shell layer Cd 0.6 Zn 0.4 S is 0.5 nm, and the thickness of the outer shell ZnS is 0.5 nm; and, as Figure 3 shown, the light-emitting layer 13 is composed of a first quantum dot layer 131 and a second quantum dot layer 132. The materials of both the first quantum dot layer 131 and the second quantum dot layer 132 are the blue quantum dots in Example 1; the blue quantum dots are arranged in a single layer in the first quantum dot layer 131 and are arranged in a single layer in the second quantum dot layer 132.

[0154] Compared with the preparation method of the light-emitting device in Example 1, the difference in the preparation method of the light-emitting device in this example is that: step S1.4 is replaced with "spin-coating a blue quantum dot - n-octane solution with a concentration of 24 mg / mL on the side of the hole transport layer away from the hole injection layer under a nitrogen environment at normal temperature and pressure, with a spin-coating speed of 2000 r / min and a spin-coating time of 15 s, and then placing it in a constant temperature heat treatment at 80 °C to cure into a film, obtaining a light-emitting layer composed of a stacked first quantum dot layer and second quantum dot layer".

[0155] Example 6

[0156] This example provides a light-emitting device and its preparation method. Compared with the light-emitting device in Example 1, the difference in the light-emitting device in this example is that: the material of the light-emitting layer is replaced with "blue quantum dot Cd 0.08 Zn 0.92 Se / ZnSe 0.2 S 0.8 / Cd 0.6 Zn 0.4 S / ZnS”, where the average particle size of the quantum dot core Cd 0.08 Zn 0.92 Se is 4 nm, the thickness of the first shell layer ZnSe 0.2 S 0.8 is 1 nm, the thickness of the second shell layer Cd 0.6 Zn 0.4 S is 0.5 nm, and the thickness of the outer shell ZnS is 0.5 nm; and, as Figure 4As shown, the light-emitting layer 13 is composed of a first quantum dot layer 131, a second quantum dot layer 132, and a third quantum dot layer 133. The materials of the first quantum dot layer 131 to the third quantum dot layer 133 are all the blue quantum dots in Example 1; the blue quantum dots in the first quantum dot layer 131 are arranged in a single layer, the blue quantum dots in the second quantum dot layer 132 are arranged in a single layer, and the blue quantum dots in the third quantum dot layer 133 are arranged in a single layer.

[0157] Compared with the preparation method of the light-emitting device in Example 1, the difference in the preparation method of the light-emitting device in this example is that: step S1.4 is replaced with "Under a nitrogen environment at normal temperature and pressure, spin-coat a blue quantum dot - n-octane solution with a concentration of 32 mg / mL on the side of the hole transport layer away from the hole injection layer at a spin-coating speed of 2000 r / min for a spin-coating time of 15 s, and then place it in a constant temperature heat treatment at 80 °C to cure into a film, obtaining a light-emitting layer composed of a first quantum dot layer to a third quantum dot layer stacked in sequence."

[0158] Comparative Example 1

[0159] This comparative example provides a light-emitting device and its preparation method. Compared with the light-emitting device in Example 1, the difference in the light-emitting device in this comparative example is that: the average particle size of the quantum dot core Cd 0.08 Zn 0.92 Se is 4 nm, the thickness of the middle shell layer ZnSe is 2 nm, and the thickness of the outer shell Cd 0.6 Zn 0.4 S is 1 nm; the difference between Ec1 and Ec2 is 0.4 eV, and the difference between Ev2 and Ev1 is 1.0 eV.

[0160] Compared with the preparation method of the light-emitting device in Example 1, the difference in the preparation method of the light-emitting device in this comparative example is that: step S1.4 is replaced with "Under a nitrogen environment at normal temperature and pressure, spin-coat a blue quantum dot - n-octane solution with a concentration of 11 mg / mL on the side of the hole transport layer away from the hole injection layer at a spin-coating speed of 2000 r / min for a spin-coating time of 15 s, and then place it in a constant temperature heat treatment at 80 °C to cure into a film, obtaining a light-emitting layer in which the blue quantum dots are arranged in a single layer."

[0161] Comparative Example 2

[0162] This comparative example provides a light-emitting device and its preparation method. Compared with the light-emitting device in Example 1, the difference in the light-emitting device in this comparative example is that: as Figure 4As shown, the light-emitting layer 13 is composed of a first quantum dot layer 131, a second quantum dot layer 132, and a third quantum dot layer 133. The materials of the first quantum dot layer 131 to the third quantum dot layer 133 are all the blue quantum dots in Comparative Example 1. In the first quantum dot layer 131, the blue quantum dots are arranged in a single layer, and in the second quantum dot layer 132, the blue quantum dots are arranged in a single layer, and in the third quantum dot layer 133, the blue quantum dots are arranged in a single layer; and, the quantum dot core Cd 0.08 Zn 0.92 Se has an average particle size of 4 nm, the thickness of the middle shell layer ZnSe is 2 nm, and the thickness of the outer shell Cd 0.6 Zn 0.4 S is 1 nm, the difference between Ec1 and Ec2 is 0.4 eV, and the difference between Ev2 and the Ev1 is 1.0 eV.

[0163] Compared with the preparation method of the light-emitting device in Example 1, the difference in the preparation method of the light-emitting device in this comparative example is that: step S1.4 is replaced with "under a nitrogen environment at normal temperature and pressure, spin-coat a blue quantum dot - n-octane solution with a concentration of 36 mg / mL on the side of the hole transport layer away from the hole injection layer, the spin-coating speed is 2000 r / min, the spin-coating time is 15 s, and then place it in a constant temperature heat treatment at 80 °C to cure into a film, obtaining a light-emitting layer composed of a first quantum dot layer to a third quantum dot layer stacked in sequence".

[0164] Experimental Example 1

[0165] Provide the first single-hole device to the eighth single-hole device. In the upward direction, each single-hole device is composed of a substrate, an anode, a hole injection layer, a hole transport layer, a light-emitting layer, and a cathode stacked in sequence. And the structural compositions of the substrate, anode, hole injection layer, hole transport layer, and cathode in each single-hole device are the same as the structural compositions of the corresponding functional layers of the light-emitting device in Example 1. The structural compositions of the light-emitting layers in the first single-hole device to the eighth single-hole device are the same as the structural compositions of the light-emitting layers in Example 1 to Example 6, Comparative Example 1, and Comparative Example 2, respectively. That is: the structural composition of the light-emitting layer in the first single-hole device is the same as the structural composition of the light-emitting layer in Example 1, the structural composition of the light-emitting layer in the second single-hole device is the same as the structural composition of the light-emitting layer in Example 2, and so on. The structural composition of the light-emitting layer in the eighth single-hole device is the same as the structural composition of the light-emitting layer in Comparative Example 2. The only difference between the first single-hole device to the eighth single-hole device lies in the different structural compositions of the light-emitting layers.

[0166] Performance detection was carried out on the first single-hole device to the eighth single-hole device. Using the Fostar FPD optical property measurement equipment (including Ocean Optics USB2000, LabView-controlled QE-PRO spectrometer, Keithley 2400, high-precision digital source meter Keithley 6485, optical fiber with an inner diameter of 50μm, device test probes and fixtures, various related connecting wires and data cards, efficiency test dark box and data acquisition system, etc., an efficiency test system was built) to detect and obtain the voltage (U HOD , V) of each single-hole device driven by a constant current (2 mA). The detection environmental conditions were: environmental temperature 25°C, environmental humidity 50%.

[0167] The performance detection data of each single-hole device are as described in Table 1 below:

[0168] Table 1 List of performance detection data of the first single-hole device to the eighth single-hole device

[0169]

[0170] As can be seen from Table 1, for a specific quantum dot as the material of the light-emitting layer, the more layers of quantum dots arranged in a single layer in the light-emitting layer, the higher the U HOD , and the lower the corresponding hole injection level.

[0171] Experimental Example 2

[0172] The first single-electron device to the eighth single-electron device were provided. In the up-down direction, each single-electron device was composed of a substrate, an anode, a light-emitting layer, an electron functional layer, and a cathode stacked in sequence. And the structural compositions of the substrate, anode, light-emitting layer, and cathode in each single-electron device were the same as those of the corresponding functional layers of the light-emitting device in Example 1. The structural compositions of the light-emitting layers in the first single-electron device to the eighth single-electron device were the same as those of the light-emitting layers in Examples 1 to 6, Comparative Example 1, and Comparative Example 2 respectively. The difference between the first single-electron device to the eighth single-electron device was only that the structural compositions of the light-emitting layers were different.

[0173] The performance detection data of each single-electron device are as described in Table 2 below:

[0174] Table 2 List of performance detection data of the first single-electron device to the eighth single-electron device

[0175]

[0176] As can be seen from Table 2, for a specific quantum dot as the material of the light-emitting layer, the more layers of quantum dots arranged in a single layer in the light-emitting layer, the higher the U EOD , and the lower the corresponding electron injection level.

[0177] Experimental Example 3

[0178] Performance tests were conducted on the encapsulated light-emitting devices in Examples 1 to 6 and Comparative Examples 1 and 2. Parameters such as the turn-on voltage, current, maximum brightness, and emission spectrum of each light-emitting device were detected using a FushiDA FPD optical property measurement device, and the device lifetime of each light-emitting device was tested using a lifetime test device. The detection environmental conditions were: ambient temperature 25°C, ambient humidity 50%.

[0179] Among them, the test method for the external quantum efficiency was: the external quantum efficiency of each light-emitting device was detected using an EQE optical test instrument, and the maximum external quantum efficiency (EQE max , %) was calculated and obtained.

[0180] The detection method for the device lifetime included the steps of: under the drive of a constant current (2 mA), the electroluminescence lifetime analysis of each light-emitting device was carried out using a lifetime test device, the time required for each light-emitting device to decay from the maximum brightness to 95% was recorded, and the time required for each single-hole device to decay from 100% to 95% in brightness at 1000 nit (LT95@1knit,h) was calculated through the decay fitting formula.

[0181] The performance test data of each light-emitting device are shown in Table 3 below:

[0182] Table 3 Summary of performance test data of the light-emitting devices in Examples 1 to 6 and Comparative Examples 1 and 2

[0183]

[0184]

[0185] As can be seen from Table 3, compared with the comprehensive performance of the light-emitting devices in Comparative Examples 1 and 2, the comprehensive performance of the light-emitting devices in Examples 1 to 6 is more advantageous, specifically manifested as: the light-emitting devices in Examples 1 to 6 have higher luminous efficiency, and the device lifetime of the light-emitting devices in Examples 1 to 6 is longer. Taking the light-emitting devices in Example 2 and Comparative Example 2 as an example, the EQE of the light-emitting device in Example 2 max is twice that of the light-emitting device in Comparative Example 3, and the LT95@1knit of the light-emitting device in Example 2 is 3.8 times that of the LT95@1knit of the light-emitting device in Comparative Example 3. max

[0186] ​It can be seen therefrom that when the average particle size of the core of the quantum dots is less than 5 nm and the thickness of the shell of the quantum dots is less than 2.5 nm, the difference between Ec1 and Ec2 is not greater than 0.2 eV, and the difference between Ev2 and Ev1 is not less than 0.8 eV, which is beneficial to improving the luminous efficiency and device life of the light-emitting device.

[0187] The above has introduced in detail a light-emitting device, a method for manufacturing the light-emitting device, and an electronic device provided by an embodiment of the present application. Specific examples are used herein to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present application; those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A light-emitting device, characterized in that, The light-emitting device includes: An anode and a cathode which are oppositely arranged; and A light-emitting layer disposed between the anode and the cathode; Wherein, the material of the light-emitting layer contains quantum dots having a core-shell structure, the average particle size of the core of the quantum dots is less than 5 nm, and the thickness of the shell of the quantum dots is less than 2.5 nm.

2. The light-emitting device according to claim 1, characterized in that, The average particle size of the core of the quantum dots is 1 nm to 4 nm, and / or the thickness of the shell of the quantum dots is 1 nm to 2.5 nm; and / or The difference between the conduction band energy level of the shell of the quantum dots and the conduction band energy level of the core of the quantum dots is not greater than 0.2 eV; and / or The difference between the valence band energy level of the shell of the quantum dots and the valence band energy level of the core of the quantum dots is not less than 0.8 eV.

3. The light-emitting device according to claim 1, characterized in that, The average particle size of the quantum dots is 2 nm to 25 nm; and / or The difference between the valence band energy level of the shell of the quantum dots and the valence band energy level of the core of the quantum dots is 0.8 eV to 1.0 eV; and / or The quantum dots are blue quantum dots; and / or The material of the core of the quantum dots and the material of the shell of the quantum dots are independently selected from one or more of II-VI group compounds, III-VI group compounds, III-V group compounds, IV-VI group compounds, and I-III-VI group compounds; optionally, the II-VI group compounds are selected from one or more of 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, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the III-VI group compounds are selected from one or more of In2S3, In2Se3, InGaS3, and InGaSe3; the III-V group compounds are selected from one or more of 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, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the IV-VI group compounds are selected from one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; the I-III-VI group compounds are selected from one or more of AgInS, AgInS2, CuInS, CuInS2, AgGaS2, CuGaS2, CuGaO2, AgGaO2, AgAlO2, AgInGaS2, and CuInGaS2; and / or The quantum dots are selected from any one of the following: (1) Zn x1 Cd (1-x1) Se / ZnSe / Cd x2 Zn (1-x2) S / ZnS, 0.85 ≤ x1 ≤ 0.95, 0.1 ≤ x2 ≤ 0.5; (2) Zn y1 Cd (1-y1) Se / ZnSe / ZnS / Cd y2 Zn (1-y2) S / ZnS, 0.85 ≤ y1 ≤ 0.95, 0.1 ≤ y2 ≤ 0.5; (3) Zn z1 Cd (1-z1) Se / Cd z2 Zn (1-z2) S / ZnS, 0.85 ≤ z1 ≤ 0.95, 0.1 ≤ z2 ≤ 0.5; (4) Cd t1 Zn (1-t1) Se / ZnSe t2 S (1-t2) / Cd t3 Zn (1-t3) S / ZnS, 0.85 ≤ t1 ≤ 0.95, 0.4 ≤ t2 ≤ 1, 0.1 ≤ t3 ≤ 0.5; (5) Cd r1 Zn (1-r1) Se / ZnSe / Cd r2 Zn (1-r2) S, 0.85 ≤ r1 ≤ 0.95, 0.1 ≤ r1 ≤ 0.

3.

4. The light-emitting device according to any one of claims 1 to 3, characterized in that, The light-emitting layer includes N quantum dot layers, the materials of each of the quantum dot layers are independently selected from the quantum dots, and the quantum dots in each of the quantum dot layers are arranged in a single layer, where N is a positive integer greater than or equal to 1.

5. The light-emitting device according to claim 4, characterized in that, The thickness of the light-emitting layer is 2 nm to 60 nm; and / or N is 2, and the light-emitting layer is composed of a first quantum dot layer and a second quantum dot layer arranged in a stack.

6. The light-emitting device according to claim 1, characterized in that, The light-emitting device further includes an electron functional layer disposed between the cathode and the light-emitting layer, and the material of the electron functional layer includes one or more of an undoped first inorganic compound and a doped second inorganic compound; Among them, the undoped first inorganic compound includes one or more of an undoped first metal oxide, a IIB-VIA group semiconductor material, a IIIA-VA group semiconductor material, and a IB-IIIA-VIA group semiconductor material. The undoped first metal oxide includes one or more of ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, and ZrO2, and / or the IIB-VIA group semiconductor material includes one or more of ZnS, ZnSe, and CdS, and / or the IIIA-VA group semiconductor material includes one or more of InP and GaP, and / or the IB-IIIA-VIA group semiconductor material includes one or more of CuInS and CuGaS; and / or, the doped second inorganic compound includes a second metal oxide doped with a first doping element, the second metal oxide is selected from ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, or ZrO2, and the first doping element is selected from one or more of Mg, Ca, Zr, W, Ga, Li, Al, Ti, Y, In, and Sn; And / or, the light-emitting device further includes a hole functional layer disposed between the anode and the light-emitting layer, and the material of the hole functional layer includes one or more of an organic compound, an undoped third inorganic compound, and a doped fourth inorganic compound; wherein, the organic compound is selected from one or more of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid), copper phthalocyanine, titanium oxyphthalocyanine, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, polypyrrole, polyaniline, 3-hexyl-substituted polythiophene, poly(9-vinylcarbazole), 4,4'-bis(9-carbazolyl)biphenyl, poly[bis(4-phenyl)(4-butylphenyl)amine], 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline], poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine)], poly[(N,N'-(4-n-butylphenyl)-N,N'-diphenyl-1,4-phenylenediamine)-ALT-(9,9-din-octylfluorene-2,7-diyl)], 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, 4,4',4''-tris(carbazol-9-yl)triphenylamine, 4,4',4'-tris(2-naphthylphenylamino)triphenylamine, N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine, N,N'-bis[4-(diphenylamino)phenyl]-N,N'-diphenylbenzidine, N,N'-bis(3-methylphenyl)-N,N'-diphenyl-9,9-spirobifluorene-2,7-diamine, N2,N7-di-1-naphthyl-N2,N7-diphenyl-9,9'-spirobi[9H-fluorene]-2,7-diamine, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], and 2,2',7,7'-tetra[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, and / or the undoped third inorganic compound is selected from one or more of graphene, C60, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, p-type gallium nitride, chromium oxide, copper oxide, copper sulfide, molybdenum sulfide, and tungsten sulfide, and / or the doped fourth inorganic compound is a host inorganic compound doped with a second doping element, and the host inorganic compound is selected from one or more of graphene, C60, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, p-type gallium nitride, chromium oxide, copper oxide, copper sulfide, molybdenum sulfide, and tungsten sulfide, and / or the second doping element is selected from one or more of nickel, molybdenum, tungsten, vanadium, chromium, copper, and platinum group metal elements; And / or, the materials of the anode and the cathode are independently selected from one or more of metals, carbon materials, and third metal oxides, wherein the metal is selected from one or more of Al, Ag, Cu, Mo, Au, Ba, Pt, Ca, Ir, Ni, and Mg, and / or the carbon material is selected from one or more of graphite, carbon nanotubes, graphene, and carbon fibers, and / or the third metal oxide is selected from one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, aluminum-doped magnesium oxide, SnO2, ZnO, and In2O3.

7. A method for preparing a light-emitting device, characterized in that, Comprising the following steps: Providing a bottom electrode and forming a light-emitting layer on one side of the bottom electrode; and Forming a top electrode on the side of the light-emitting layer away from the bottom electrode; Wherein, one of the bottom electrode and the top electrode is an anode and the other is a cathode; the material of the light-emitting layer comprises quantum dots having a core-shell structure, the average particle size of the core of the quantum dots is less than 5 nm, and the thickness of the shell of the quantum dots is less than 2.5 nm.

8. The preparation method according to claim 7, characterized in that, The difference between the conduction band energy level of the shell of the quantum dots and the conduction band energy level of the core of the quantum dots is not greater than 0.2 eV; and / or The difference between the valence band energy level of the shell of the quantum dots and the valence band energy level of the core of the quantum dots is not less than 0.8 eV; and / or The method for forming the light-emitting layer comprises the steps of: Depositing a dispersion liquid containing the quantum dots to obtain a first film layer; And Performing a drying treatment on the first film layer to obtain the light-emitting layer; Wherein, the first film layer comprises N quantum dot layers, the material of each quantum dot layer is the quantum dots, and the quantum dots in each quantum dot layer are arranged in a single layer, and N is a positive integer greater than or equal to 1.

9. The preparation method according to claim 8, characterized in that, The relationship between the number of formed quantum dot layers and the concentration of the quantum dots in the dispersion liquid is as follows: (B1) N is 1, and the concentration of the quantum dots in the dispersion liquid is 5 mg / mL to 7 mg / mL; (B2) N is 2, and the concentration of the quantum dots in the dispersion liquid is 21 mg / mL to 24 mg / mL; (B3) N is 3, and the concentration of the quantum dots in the dispersion liquid is 28 mg / mL to 32 mg / mL.

10. An electronic device, characterized in that, The electronic device comprises a light-emitting device as described in any one of claims 1 to 6, or the electronic device comprises a light-emitting device prepared by the preparation method as described in any one of claims 7 to 9.

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